JPH08216908A - Steering controller for vehicle - Google Patents

Abstract

PURPOSE: To reduce the manufacture cost of the whole system by equipping this steering controller with a first control means, which computes the objective steering angle repeatedly in every specified period, based on a sensor signal, and sends it as an instruction value, and a second control means which adjusts the quantity of energization of a drive means, based on its instruction value. CONSTITUTION: This steering controller is equipped with two kinds of steering angle detectors 17 and 20 and car velocity detectors 22 and 23, installed each in different parts, and a yaw rate detector 24, and those output signals are inputted into ECU 9 as the first drive means. Here the objective steering angle is computed repeatedly, and it sends information geared to the objected steering angle as instruction value. Based on the instruction value from this CPU 9 and the quantity of state of a steering system being the object of control, a servo unit SVU as the second control means controls an electric motor 12. SVU also sends an instruction value request signal to CPU 9 in approximately fixed period, and CPU 9 sends the information of instruction value to SVU, answering the instruction value request signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering control device that can be used in an automobile.

[0002]

2. Description of the Related Art Conventionally, in automobiles, the rear wheels are steered by an actuator such as an electric motor in conjunction with the steering amount of the front wheels.

This type of steering control device is composed of various sensor groups including, for example, a front wheel steering angle sensor, a vehicle speed sensor, a rear wheel steering angle sensor, a motor speed sensor, an electric motor and gears. And an electronic control unit for controlling the energization of the electric motor, which includes a microcomputer and a driver.

[0004]

By the way, in the case of the rear wheel steering control device, it is necessary to supply a relatively large current to the electric motor of the actuator, so that the electronic control unit and the actuator are connected to each other. Therefore, unless a thick electric wire is used or the length of the electric wire is shortened, power loss increases. Therefore, it is desirable to install the electronic control unit near the actuator.

However, the electronic control unit includes, for example, a yaw rate sensor, a front wheel steering angle sensor, a wheel speed sensor,
Since it is necessary to connect to a number of sensors that are located away from the rear wheels, such as a T / M (transmission) vehicle speed sensor,
If the electronic control unit is placed near the rear wheel, the wiring connecting the multiple sensors and the electronic control unit must be routed over a long distance, increasing the amount of wiring and increasing the sensor or electronic control unit. Since various signals input to the unit are easily affected by electric noise, a problem occurs.

In order to avoid such a problem, two independent electronic control units are provided, one electronic control unit is arranged in the vicinity of various sensors, and the other electronic control unit is arranged in the vicinity of the actuator. It is desirable to configure it to be arranged. In addition, the two electronic control units share the control, and the information such as the target steering angle is generated by one unit and transmitted to the other unit, and based on the information such as the steering angle input by the other unit. It is desirable to implement servo control of the motor.

However, in the steering control device composed of two independent electronic control units, there are various problems to be solved as described below.

(1) Information such as the target rudder angle must be reliably transmitted between the two units to avoid the loss of information and the occurrence of inconsistency in the target rudder angle between the units.
This point can be solved by controlling the processing timings of the two units to be synchronized with each other.
For example, in each of the two units, one cycle of repeating various calculations and processes may be fixed at 5 msec, and information such as the target steering angle may be transmitted for each cycle. However, when the processing timings of the two units are synchronized, the responsiveness of the entire control system is limited by whichever of the two units is slow in operation. For example, one cycle of one unit is 5 msec
If the value is changed from 10 msec to 10 msec, one cycle of the other unit must be changed to 10 msec, which deteriorates the responsiveness. For example, although a relatively long cycle for updating the target rudder angle does not cause any problem, a servo system that controls an electric motor that actually adjusts the rudder angle requires fast response. It On the other hand, regarding the unit that generates the target rudder angle, the processing contents are not complicated, and there is room to execute other processing.Since various sensors are connected, the structure and wiring of various on-board devices can be reduced. For simplification and cost reduction of the whole device, in one unit,
It is desirable to include not only the steering angle control but also other control systems such as suspension control, vehicle speed control, brake control, transmission control and the like. However, if the functions of various control systems are included in one unit, it is inevitable that the control cycle in that unit becomes long, and accordingly, the responsiveness of the steering servo system deteriorates.

Therefore, even when the processing of various control systems is executed in a single control unit that generates information such as the target steering angle, it is possible to prevent the responsiveness of the steering servo system from deteriorating. That is one issue.

(2) By the way, when two electronic control units are installed, it is necessary to transmit information such as a target steering angle between the electronic control units. Moreover, information such as the target rudder angle may change in a short cycle, so information must be transmitted frequently, and in order to improve control responsiveness, increase the information transmission speed. There is a need. However, increasing the transmission rate of information increases the frequency of the signal passing between the two electronic control units. When a high frequency signal is transmitted, the signal emits high frequency noise, which causes various problems. In addition, if parallel data transmission is performed to reduce the signal frequency, the number of wirings connecting the two electronic control units increases, which is not desirable. Also, if the number of times that one electronic control unit generates information such as the target steering angle does not match the number of times that the other electronic control unit receives the information, the target steering angle does not match between the units, resulting in an abnormal condition. Steering control may be performed.

Therefore, it is possible to reduce the performance of the device by 2 without sacrificing the performance of the device.
Another challenge is to reduce the amount of information transmitted between the two control units and to prevent the target steering angle inconsistencies between the units.

(3) Further, for example, when data of the target rudder angle is transmitted, if data error occurs due to the influence of noise, etc., the target rudder angle becomes uniform between the two electronic control units separated from each other. This may result in abnormal steering control being performed.

Therefore, it is another object of the present invention to prevent abnormal steering control from being performed and to provide a more reliable steering control device when data error occurs (4). Further, for example, when transmitting the information of the target rudder angle, data error may occur under the influence of strong noise, but control is performed so as to immediately stop the operation when the data error is detected. Then, in a noisy environment, steering control may stop frequently, which is not desirable.
However, if the data that causes the error is used, abnormal steering control may be performed and the mechanism of the drive system may be damaged. Resolving such a problem is also one problem.

(5) By the way, when the engine of the automobile is started, the voltage of the battery, which is the power supply source, is temporarily greatly reduced. For example, in a circuit using a digital processor such as a microcomputer, a reset signal is generated and the operation is initialized when the power supply voltage is significantly reduced. In an apparatus including two electronic control units separated from each other, the power supply lines of the respective electronic control units are separated, so that each electronic control unit can generate a reset signal independently, that is, at different timings. There is a nature. When a reset signal is generated in only one electronic control unit,
A communication abnormality is detected in the other electronic control unit. Therefore, in an apparatus that stops its operation when a communication abnormality is detected, the operation of the apparatus may stop each time the engine is started. However, if the detection of the communication abnormality is omitted, the steering control may be performed with respect to the abnormal target steering angle, and the malfunction cannot be prevented.

Therefore, it is an object to prevent malfunction of the device due to communication abnormality and to prevent the function of the device from stopping when the engine is started.

(6) By the way, in this type of device,
For example, when an abnormality such as a runaway of the microcomputer occurs, the electric motor for driving the steering mechanism is prevented from being abnormally controlled. It is desirable to install a relay having a function of cutting off the energization of the motor driver for controlling the power supply circuit in the power supply circuit.
Further, the first control unit for generating the target rudder angle and the second control unit including the driver and the servo control system for controlling the energization of the electric motor are provided with independent micro computers. In this case, it is desirable that the relay be controlled to shut off the power source of the driver when any of the control units detects an abnormality. However, the following problems may occur when diagnosing the device. In diagnosing the device, it is necessary to check whether the relay is turned on / off normally and whether the driver circuit is normal. Diagnosis of the driver circuit is carried out under the control of the second control unit, at which time the relay must be on. However, since the relay may be turned on / off under the control of the first control unit, for example, the timing of power-on of the two control units may be shifted or the reset signal may be applied to one of the control units. When the relay is in the off state, the second control unit may diagnose the driver circuit, and the malfunction may be erroneously detected when the function of the device is normal.

Therefore, it is also an object to eliminate the error in detecting the failure of the device itself.

[0018]

In order to solve the above-mentioned problems, a vehicle steering control device according to a first aspect of the present invention provides a sensor means (17, 20, 22, 2) for detecting information relating to the state of the vehicle.
3, 24); including a first digital processor (1),
A first connected to the sensor means, repeatedly calculating a target steering angle (T1) based on information detected by the sensor means, and transmitting information according to the calculated target steering angle as an instruction value (ΔT2). Control means (9); drive means (12) for adjusting the steering angle; and a second digital processor (8) independent of the first digital processor, the first control means transmitting In a steering control device for a vehicle, comprising: second control means (SVU) for inputting information on an instruction value and adjusting the bias amount of the drive means based on the instruction value and the state quantity of the control target steering system: With a nearly constant cycle,
A signal generating means (S62) for sending an instruction value request signal from the second control means to the first control means; and in response to the instruction value request signal, the first control means to the second control means. To the transmission control means (S3
E);

Further, in the present invention, the first control means includes a change amount calculation means (S16) for generating information (ΔT) corresponding to the calculated change amount of the target steering angle as the instruction value. The second control means includes a cumulative value calculation means (S2C) for calculating a cumulative value of the instruction values sent from the first control means, and the first control means further comprises:
When the calculation of the target rudder angle cannot be completed in time for the instruction value request signal from the second control means, 0 is set as the instruction value to the second value.
Indicated value correction means (S3B, S3)
C).

Further, in the present invention, the first control means (9) includes means (S17) for comparing the calculated change amount of the target steering angle with a predetermined upper limit value, and the second control means is provided. A limiter means (S18) for limiting the instruction value transmitted to the means to within the upper limit value is provided.

Further, in the present invention, the second control means compares the magnitude of the instruction value sent from the first control means with a predetermined upper limit value to identify the presence or absence of the first abnormality. Means (S42), means (S2B, S2i) for invalidating the latest indication value and reusing the indication value received in the past when the first abnormality is detected, and repeating the first abnormality a plurality of times Means for detecting a second abnormality (S69, S6A, S6B) when detected, and means (S2) for braking the drive means when a second abnormality is detected.
A, S2G).

Further, in the present invention, the second control means is an abnormality detection means (S42, S69, S6) for detecting an abnormality in the instruction value sent from the first control means.
A, S6B), a means for performing a predetermined abnormality processing when an abnormality is detected by the means (S2G), a means for detecting the power supply voltage of the second control means (S63), and a second
The detection prohibiting means (S6C) for prohibiting the abnormality detection of the abnormality detecting means when the power supply voltage of the control means is abnormal.

In the sixth aspect, the second control means prohibits the steering angle adjustment of the drive means when the power supply voltage of the second control means is abnormal (S29, S2G).
including.

Further, in claim 7, the second control means is an abnormality detection means (S42, S69, S6) for detecting an abnormality in the instruction value sent from the first control means.
A, S6B), means for performing a predetermined abnormality processing when an abnormality is detected by the means (S2G), means for identifying whether the engine is operating (S66), and when the engine is stopped And a detection prohibiting means (S6C) for prohibiting the abnormality detection of the abnormality detecting means.

Further, in the present invention, the second control means includes means (S29, S2G) for prohibiting the steering angle adjustment of the drive means when the engine is stopped.

Further, in claim 9, the sensor means (17, 20, 22, 23, for detecting the information on the state of the vehicle).
24); including a first digital processor, connected to the sensor means, repeatedly calculating a target rudder angle based on information detected by the sensor means, and using information according to the calculated target rudder angle as an instruction value A first control means (9) for transmitting; a driving means (12) for adjusting the steering angle; and a second digital processor independent of the first digital processor, the first control means comprising: A vehicle steering control device comprising second control means (SVU) for inputting information on an instruction value to be transmitted and adjusting the bias amount of the drive means based on the instruction value and the state quantity of the control target steering system. In: switching means (3) provided in the first control means for switching on / off of a power source connected to the drive means; provided in the first control means, in a predetermined diagnostic mode, Said Controls the quenching means, power control means (S11 to transmit the information indicating the state of said switching means to said second control means, S71～S
76); and provided in the second control means, in the diagnostic mode, the information transmitted from the first control means is input to identify the state of the switching means, and the state of the switching means. And failure detection means (S21, S81 to S86) for diagnosing the presence or absence of a failure based on the state of the driver that controls the energization of the drive means.

The symbols shown in parentheses above are the reference numerals of the corresponding elements in the examples described later, but each component of the present invention is a specific element in the examples. It is not limited to only.

[0028]

In the present invention, the sensor means (17, 20,
22, 23, 24) is connected to the input of the first control means (9) and the drive means (12) is the second control means (S).
VU) output. Also, the first control means includes a first digital processor (1), and the second control means includes a second digital processor (8) independent of the first digital processor. Each of the first digital processor and the second digital processor may be a general-purpose control means such as a microcomputer in which a specific program is incorporated, or dedicated hardware for executing a specific processing function. It may be a circuit.
Then, the first control means repeatedly calculates the target steering angle (T1) every predetermined period (for example, 5 msec) based on the information detected by the sensor means, and obtains information according to the calculated target steering angle. It is sent as an instruction value. The second control means inputs the information of the instruction value transmitted by the first control means, and adjusts the urging amount of the drive means based on the instruction value and the state quantity of the control target steering system.

Information transmission between the first control means and the second control means is carried out as follows. An instruction value request signal repeatedly generated by the signal generating means (S62) at a substantially constant cycle is sent from the second control means to the first control means. In the first control means, each time the indication value request signal is detected, the transmission control means (S3E) sends the indication value information to the second control means in response to the indication value request signal. send.

Therefore, the timing at which the information of the indicated value is transmitted from the first control means to the second control means is repeatedly generated in the cycle in which the instruction value request signal is generated. That is, regardless of the cycle of the processing cycle repeatedly executed by the first control unit, the information of the instruction value is the first at a constant cycle.
Is transmitted from the control means to the second control means. Therefore, it is not necessary to synchronize or make the cycle of the processing cycle repeatedly executed by the first control means and the cycle of the processing cycle repeatedly executed by the second control means. That is,
In order to maintain the high responsiveness of the steering servo system, the cycle of the processing cycle executed by the second control means is fixed to be sufficiently short and, if necessary, the processing cycle executed by the first control means. The cycle of can be lengthened. Therefore, it becomes possible to centrally control various on-vehicle devices by the first control means including various functions other than the steering control. That is, when various on-board devices are mounted on an automobile, sharing the control unit not only reduces the number of control units but also significantly reduces wiring, which significantly reduces the manufacturing cost of the entire system. It can be reduced.

In the second aspect, information (ΔT) corresponding to the amount of change in the target steering angle is sent from the first control means to the second control means as an instruction value. The second control means accumulates the indicated values to obtain the target rudder angle. Since the amount of change in the target rudder angle within the predetermined period is much smaller than the value that the target rudder angle can take, it is possible to represent the former information with a far smaller number of bits than the latter information. it can. That is, by transmitting the amount of change in the target steering angle from the first control means to the second control means, the number of bits of information to be transmitted is reduced, so that the transmission speed can be reduced. When the transmission rate is not changed, the required transmission time is shortened.

However, since the processing executed by the first control means and the processing executed by the second control means are asynchronous, the processing of the first control means is executed in response to the request of the second control means. It may not be in time. However, since the change amount of the target rudder angle is transmitted from the first control means to the second control means, the number of times (cycle) the first control means generates the target rudder angle and the second control means When there is a difference between the number of times (cycle) of receiving the change in the steering angle, the target steering angle generated by the first control means and the target steering angle (cumulative change accumulated by the second control means). (Arithmetic value) may not match. In order to avoid this, if the instruction value correction means (S3B, S3C) of the first control means cannot calculate the target steering angle in time for the instruction value request signal from the second control means, 0 is transmitted to the second control means as an instruction value.

In the third aspect, the change amount of the target steering angle transmitted from the first control means to the second control means is limited within a predetermined upper limit value. Therefore, when the information received by the second control means exceeds the upper limit value, it can be considered that an abnormality such as data error has occurred.
By detecting the abnormality, malfunction can be prevented.

According to a fourth aspect of the present invention, the presence or absence of the first abnormality is identified in the second control means by comparing the magnitude of the instruction value sent from the first control means with a predetermined upper limit value. , If the first abnormality is detected,
The latest instruction value is invalidated and the instruction value received in the past is reused. By this control, abnormal steering control can be prevented and the steering control can be continued. Therefore, it is possible to avoid frequent stoppage of the operation of the device even in an environment susceptible to noise. However, when the first abnormality is repeatedly detected a predetermined number of times or more, the normal operation is no longer guaranteed, so that it is considered that the second abnormality has occurred and the drive means is braked to stop the automatic steering.

In the present invention, the second control means detects whether or not there is an abnormality in the instruction value sent from the first control means, and when the abnormality is detected, the predetermined abnormality processing is executed. Also, by detecting the power supply voltage of the second control means,
If the detected power supply voltage is abnormal, the detection of abnormality related to the indicated value is prohibited. Further, in claim 6, when the power supply voltage of the second control means is abnormal, the steering angle adjustment of the drive means is prohibited. As a result, when data error occurs in the instruction value sent from the first control means to the second control means due to the decrease in the power supply voltage at the time of starting the engine, the steering angle adjustment is temporarily stopped. Only then, the normal rudder angle adjustment is performed after the engine is started. There is no fear that abnormal rudder angle adjustment will be performed.

In the seventh aspect, the second control means detects whether or not there is an abnormality in the instruction value sent from the first control means, and when the abnormality is detected, the predetermined abnormality processing is executed. Further, it is identified whether or not the engine is in operation, and when the engine is stopped, the abnormality detection regarding the indicated value is prohibited. Further, in claim 8, the steering angle adjustment of the drive means is prohibited when the engine is stopped.

In the ninth aspect, the switching means (3) for switching on / off of the power source connected to the driving means is provided. Then, the power supply control means (S11, S71 to S76) of the first control means controls the switching means in a predetermined diagnostic mode, and at the same time, provides information indicating the state of the switching means to the second control means. Send to. Failure detection means (S21, S) of the second control means
81-S86) is the first mode in the diagnostic mode.
The information transmitted from the control means is input to identify the state of the switching means, and the presence or absence of a failure is diagnosed based on the state of the switching means and the state of the driver controlling the energization of the driving means. .

According to this, for example, when the microcomputer of the second control means runs out of control, the first control means can control the switching means to shut off the power supply of the driving means, which is safe. Is. Further, since the second control means can surely know the state of the switching means, it is possible to make a correct diagnosis when diagnosing the driver circuit and the like.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a steering system of an automobile for implementing the present invention. In FIG. 1, 13 is the left front wheel, and 14
Is the right front wheel, 15 is the left rear wheel, and 16 is the right rear wheel. The steering shaft of the steering wheel 19 is connected to the front wheel steering mechanism 10. The front wheel steering mechanism 10 includes
The rack and pinion mechanism is built in, and when the pinion rotates in conjunction with the rotation of the steering wheel 19,
When the rack shaft 10a formed with a rack that meshes with the rack shaft 10a moves in the axial direction (left-right direction) and the rack shaft 10a moves,
The steering angles of the front wheels 13 and 14 connected to it change.

In this embodiment, two types of steering angle detectors 17 and 20 are installed to detect the steering angle of the front wheels. The rudder angle detector 17 is a potentiometer for detecting the axial position of the rack shaft 10 a, and the rudder angle detector 20
Is a rotary encoder that generates a pulse as the steering shaft of the steering wheel 19 rotates. The signals output from the steering angle detectors 17 and 20 are input to an electronic control unit (ECU) 9 installed in the vehicle compartment.

Two kinds of vehicle speed detectors 22 and 23 are installed to detect the vehicle speed. Vehicle speed detector 22
Detects the vehicle speed based on the actual rotation speed of the wheels, and the vehicle speed detector 23 detects the vehicle speed based on the rotation speed of the output shaft of the transmission. Further, a yaw rate detector 24 is installed to detect the yaw rate of the vehicle body. The signals output from the vehicle speed detectors 22 and 23 and the yaw rate detector 24 are input to the electronic control unit 9, respectively.

Further, in this embodiment, the output (L terminal) of the regulator REG is connected to the electronic control unit 9 and the servo unit SVU in order to identify whether or not the engine is rotating. The regulator REG is a device that stabilizes the output voltage of the vehicle-mounted generator connected to the output of the engine.

The rear wheels 15 and 16 are connected to the rack shaft 25, and the steering angles of the rear wheels 15 and 16 change as the rack shaft 25 moves in the axial direction (left-right direction). The rack shaft 25 is connected to the rear wheel steering mechanism 11. The rear wheel steering mechanism 11 is an electric motor (brushless motor) 1 for driving.
2. A magnetic pole sensor 18 for detecting the rotational position of the electric motor 12, a servo unit SVU, and a speed reducer (not shown) are incorporated. The servo unit SVU drives the electric motor 12 based on the target steering angle information input from the electronic control unit 9. When the electric motor 12 is driven, the rack shaft 25 connected to it via the reduction gear moves,
The steering angle of the rear wheels changes. A rudder angle detector 21 is installed on the rack shaft 25 to detect the rudder angle of the rear wheels. The steering angle detector 21 is a potentiometer. The signal output from the steering angle detector 21 is input to the servo unit SVU.

The first power supply line DIG connected to the battery-2 via the ignition switch IG is connected to the electronic control unit 9 and the servo unit SVU. The first power supply line DIG is wired using an electric wire having a diameter of 0.3 mm (or 0.5 mm) because the flowing current is relatively small. On the other hand, the second power supply line PIG connected to the battery-2 via the relay-3 is connected to the servo unit SVU. Since the second power supply line PIG has a large flowing current, it is wired using an electric wire having a diameter of 3 mm.

The actual rear wheel steering mechanism 1 of the apparatus shown in FIG.
The configuration of No. 1 is shown in FIG. Referring to FIG. 2, the servo unit SVU, the electric motor 12, the magnetic pole sensor 18, and the steering angle detector 21 are built in the same housing of the rear wheel steering mechanism 11. The servo unit SVU is connected to the power supply lines PIG and DIG and the electronic control unit 9 via the connector CN. The servo unit SVU and the electric motor 12 are connected inside the housing by a short electric wire.

With such a structure, the number of wirings for connecting the rear wheel steering mechanism 11 to the power supply line and the electronic control unit 9 is very small, and in particular, the wiring through which a large current flows is the power supply line PIG. Since it is only the ground, the power loss can be minimized. Servo unit S
Since the VU and the electric motor 12 are connected by a short electric wire inside the housing, there is almost no loss of electric power at this portion.

On the other hand, the electronic control unit 9 has various sensors (17, 2) instead of being separated from the rear wheel steering mechanism 11.
2, 23, 24), the electric wires connecting these sensors and the electronic control unit 9 are relatively short, and the wiring is easy to handle. Since it is necessary to supply a stabilized voltage to each sensor, it is necessary to connect at least three electric wires to the electronic control unit 9 per sensor, and a short electric wire brings about a great advantage. In addition, since the length of the electric wire is short, it is less likely to be affected by electric noise from the outside. As will be described later, the number of electric wires is small in the portion connecting the electronic control unit 9 and the servo unit SVU. Therefore, even if the wiring in this portion becomes long, the influence of electric noise from the outside will not occur. It's easy to get rid of. For example, if the impedance of the signal line is lowered, the influence of external electrical noise will be reduced.

The structure of the electronic control unit 9 of FIG. 1 is shown in FIG. 3, and the structure of the servo unit SVU is shown in FIG. First, the electronic control unit 9 will be described with reference to FIG.
The electronic control unit 9 includes a microcomputer 1, a power supply unit 4, a voltage monitoring circuit 6, an AND gate G1, a driver DV1, and interfaces IF1 and IF2. The microcomputer 1 includes an A / D converter,
Built-in timer and serial communication circuit. The power supply unit 4 includes a stabilized power supply that outputs a stabilized voltage of 5V, a reset circuit that outputs a reset signal when the power is turned on and when the power supply voltage drops, and a watchdog timer circuit that detects an abnormality. . Interface IF
Reference numeral 1 and IF2 are signal processing circuits that perform signal waveform shaping, amplification, level adjustment, and the like.

The input port of the microcomputer 1 is connected to the sensor 2 via the interface IF1.
Signals relating to yaw rate, front wheel steering angle 1, front wheel steering angle 2, wheel speed, and transmission vehicle speed are input from 4, 17, 20, 22, and 23, respectively. In addition, the regulator REG
The engine rotation signal from the power supply and the battery voltage signal from the power supply line are also applied. Since the signals of the yaw rate, the front wheel steering angle 1, and the battery voltage applied to the input port of the microcomputer 1 are analog voltages, the levels of these voltages are built in the microcomputer 1. The sampled data is sampled by the A / D converter every predetermined period, converted into a numerical value, and stored in the memory. Further, since the front wheel steering angle 2, the wheel speed, and the transmission vehicle speed are pulse signals, the pulse cycle of each signal is measured by the timer built in the microcomputer 1 at predetermined intervals.
The measurement result is converted into the steering angle or the vehicle speed and stored in the memory. The engine rotation signal indicates whether or not the engine is rotating 2
It is a value signal.

Electronic control unit 9 and servo unit SV
U is connected to U by four signal lines RLS, RXD, TXD and CLK. Of these, the signal lines RXD, TXD and CLK are interface IF2.
It is connected to the serial communication circuit of the microcomputer 1 via. RXD is a signal line through which a binary signal (serial data) transmitted from the servo unit SVU to the microcomputer 1 is passed, and TXD is transmitted from the microcomputer 1 to the servo unit SVU. Is a signal line through which a binary signal (serial data) is passed, and CLK is a signal line through which a clock pulse having a constant cycle that determines the timing of communication data is passed. In this embodiment, the signal output to the signal line CLK is generated and output by the microcomputer 1.

RLS is a signal line for passing a power-supply cutoff signal output from the servo unit SVU. In this example, when the voltage monitoring circuit 6 detects an abnormally low power supply voltage, when the microcomputer 1 outputs a power supply power-off signal to the output port RLM, and when the servo unit S is operated.
When the gate G1 detects any one of the conditions when the VU outputs a power supply cutoff signal to the signal line RLS, the relay-3 cuts off the power supply to the power supply line PIG of the power system.

Next, referring to FIG. 4, the servo unit SV
U will be explained. In this example, the servo unit SVU is
Microcomputer 8, power supply unit 71, interface
Face IF3, resistor R1, driver DV2, DV3
And a clock detection circuit SCK. The microcomputer 8 contains an A / D converter, a timer and a serial communication circuit. The power supply unit 71 includes a stabilized power supply that outputs a stabilized voltage of 5V, a reset circuit that outputs a reset signal when the power is turned on and when the power supply voltage drops, and a watchdog timer circuit that detects an abnormality. . The interface IF3 is a signal processing circuit that performs signal waveform shaping, amplification, level adjustment, and the like. The clock stop detection circuit SCK is a circuit for identifying whether or not a clock pulse having a predetermined cycle appears on the signal line CLK.

Electronic control unit 9 and servo unit SV
Of the four signal lines RLS, RXD, TXD and CLK that connect with U, the signal lines RXD, TXD and CLK are
Microcomputer via interface IF3
Signal line RL
S is connected to the output port RLS of the microcomputer 8. The microcomputer 8 uses a signal line TXD
The binary signal (serial data) appearing in is input and the binary signal is output to the signal line RXD. The timing of these signals is determined by the signal on the signal line CLK. The signal on the signal line CLK is also applied to the clock stop detection circuit SCK.

The output signal of the clock stop detection circuit SCK is applied to the input port P11 of the microcomputer 8 and the driver DV2. Clock stop detection circuit SC
When the clock stop detection circuit SCK detects an abnormality by the signal BRK applied to the driver DV2 from K, the driver DV2 stops the motor control and enters the braking state by the control of the hardware incorporated therein. To do. When the clock stop detection circuit SCK detects an abnormality,
The software control of the microcomputer 8 also brings the motor control into the braking mode. That is, in this embodiment, double safety measures are taken against the stop of the clock signal by hardware control and software control.

The driver DV2 is a single integrated circuit, and has an amplifier 74, current level detectors MS and MOC, a booster circuit 75, a logic circuit 72, a PWM synthesizing circuit 73, current limiting circuits CL1 and CL2, and a gate driver. 76, 77 and the overheat sensor OHS are built in. The driver DV3 is
6 sets of switching units U11 consisting of a switching element (power MOS FET) and a protection diode,
It is composed of U12, U13, U21, U22, and U23, and its output is connected to the star-connected 3 of the electric motor 12.
The terminals of the phase coils U, V, W are connected.

The resistor R0 outputs a voltage corresponding to the current flowing through the driver DV3, and the level of this voltage is amplified by the amplifier 74.
Will be amplified. The current level detectors MS and MOC change the output voltage of the amplifier 74 to the threshold values ref1 and r1, respectively.
Whether or not the current is excessive is identified by comparing with ef2. Signals S1 and S output by the current level detectors MS and MOC
2 is a microcomputer 8 and a current limiting circuit CL
1, CL2.

To drive the electric motor 12, U →
It is necessary to pass a current between any one of the terminals V, V → W, W → U, V → U, W → V, and U → W, and to sequentially switch the terminals through which the current is passed. 6 sets of switching units U1
By turning on a pair of 1, U12, U13, U21, U22, U23, a current can be passed between the terminals of the electric motor 12. However, when the paired transistors of the switching units U11 and U21, U12 and U22, and U13 and U23 are turned on at the same time, the power supply line P
Such a situation must be avoided, as there is a short between IG and PGND.

Normally, the microcomputer 8 has its output ports LA1, LB1, LC1, LA2, LB2, L.
Since an appropriate signal is output to C2 and a current is caused to flow between the terminals of the electric motor 12, a short between the power supply lines PIG and PGND does not occur. However, the logic circuit 72 discriminates the combination of the states of the input signals, and the microcomputer 8
Even if an abnormality occurs in the operation of, the paired transistors of the switching units U11 and U21, U12 and U22, and U13 and U23 are controlled so as not to be turned on at the same time.

The drive torque of the electric motor 12 is adjusted by PWM (pulse width modulation) control of the current flowing through the coil. The PWM signal that determines the pulse width of the current is output from the output port PWM of the microcomputer 8. The PWM synthesizing circuit 73 is a microcomputer.
The PWM signal output from the port 8 to the port PWM and the port L
The lower side switching units U21, U22, U2 are combined with the phase switching signals output to A2, LB2, LC2.
A binary signal for controlling ON / OFF of 3 is generated.

The microcomputer 8 has ports LA1 and LA1.
The phase switching signal output to LB1 and LC1 is the logic circuit 7
2. Inputting to the gate terminals of the switching units U11, U12 and U13 via the current limiting circuit CL1 and the gate driver 76, respectively, and the micro computer 8 outputs them to the ports LA2, LB2 and LC2. The phase switching signal is input to the gate terminals of the switching units U21, U22 and U23 via the PWM synthesizing circuit 73, the current limiting circuit CL2 and the gate driver 77, respectively. Switching units U11, U12, U13,
U21, U22, and U23 are turned on / off according to the level of the binary signal input to the gate terminal.

Electric motor 12 used in this embodiment
Is a brushless motor in which the rotor is a permanent magnet and the stator is an electric coil. Therefore, in order to rotate the electric motor 12 as desired, it is necessary to always detect the position of the magnetic pole of the rotor and switch the coil through which the current flows depending on the position of the magnetic pole and the moving direction. In this embodiment, a magnetic pole sensor 18 for detecting the position of the magnetic pole of the rotor of the electric motor 12 is built in the electric motor 12. The magnetic pole sensor 18 outputs the detected three-phase signals
Input ports HA, HB, HC of the micro computer 8.
Apply to. The micro computer 8 has an input port H.
The position of the magnetic pole is detected by referring to the signals of A, HB and HC,
The phase switching signal generated based on the detected position is output to the ports LA1, LB1, LC1, LA2, LB2 and LC2.

The steering angle detector 21 for detecting the steering angle of the rear wheels is
A voltage corresponding to the rudder angle is input to the micro computer 8.
To VRS. The microcomputer 8 periodically samples the voltage level of the input port VRS, converts it into a numerical value with a built-in A / D converter, and stores the result in a memory. In this embodiment, the microcomputer 8 is based on the rudder angle initial value initially detected by the rudder angle detector 21 and the rudder angle change amount obtained by counting the signals output by the magnetic pole sensor 18. , The actual steering angle value of the rear wheels is obtained.

Overheat sensor O built in the driver DV2
The HS has a thermistor TS and a circuit for binaryly identifying its state. Overheat sensor OHS is driver D
Since it is built in the V2, it is possible to detect the temperature rise due to the heat generation of the driver DV2 itself and the heat generation of the driver DV3 located in the vicinity thereof. Then, a binary signal indicating the presence or absence of an abnormal temperature rise is applied to the input port OHW of the microcomputer 8.

The main routine of the operation of the microcomputer 1 of the electronic control unit 9 shown in FIG. 3 is shown in FIG. 5, and the main routine of the operation of the microcomputer 8 of the servo unit SVU shown in FIG. Chin is shown in FIG. First, the operation of the microcomputer 1 will be described with reference to FIG.

When the power is turned on, initialization is executed in step S10. That is, the CPU itself is checked, the memory is cleared, the parameters are initialized (including the clearing of T.theta. Described later), and various mode sets are executed. Next step S
At 11, it is diagnosed whether or not the steering control device operates normally. When the microcomputer 1 of the electronic control unit 9 executes the diagnosis in step S11, normally,
The micro computer 8 of the servo unit SVU is shown in FIG.
Step S21 of is executed.

Microcomputer 1 in step S11
12 and the details of the operation of the microcomputer 8 in step S21 are shown in FIG. The diagnostic operation will be described with reference to FIG. The microcomputer 1 first controls the relay unit SV by turning off the relay-3 in step S71.
Shut off power supply to U's driver. Then, in the next step S72, the status information indicating that the relay-3 is off is transmitted to the servo unit SVU in the form of serial information via the interface IF2 and the signal line TXD. To do. In the next step S73, the servo unit SVU is connected to the interface IF2 and the signal line R.
Monitor serial information entered via XD. If the predetermined completion code 1 is not detected, the process returns from step S73 to S71. When the completion code 1 is detected in step S73, the process proceeds to the next step S74.

On the other hand, the microcomputer 8 receives the signal line TX from the electronic control unit 9 in the first step S81.
The serial information input via D and the interface IF3 is monitored. Then, if the information indicating the relay-off state is not detected, the process of step S81 is repeated, and if the information indicating the relay-off state is detected, that is,
After the microcomputer 1 executes step S72, it proceeds to the next step S82.

In step S82, when the power supply to the power supply line PIG is cut off, the driver D
The states of V2 and DV3 are checked to identify the presence / absence of abnormality. When this process is completed, the process proceeds to the next step S83, and the predetermined completion code 1 is transmitted to the electronic control unit 9 in the form of serial information via the interface IF3 and the signal line RXD. Then, the process proceeds to the next step S84.

The microcomputer 8 makes a step S83.
After executing, the microcomputer 1 executes the step S
A complete code is detected at 73, and the process proceeds to the next step S74. In step S74, relay-3 is turned on to start supplying power to the driver of servo unit SVU. Then, in the next step S75, the status information indicating that the relay-3 is in the ON state is transmitted to the servo unit SVU in the form of serial information via the interface IF2 and the signal line TXD. To do.

The microcomputer 8 operates in step S8.
At 4, the serial information input from the electronic control unit 9 via the signal line TXD and the interface IF3 is monitored. If the information indicating the relay-on state is not detected, the processing of step S84 is repeated, and if the information indicating the relay-on state is detected, that is, after the microcomputer 1 executes step S75, The microcomputer 8 proceeds to the next step S85.

The microcomputer 8 operates in step S8.
In step 5, on the assumption that a predetermined power is supplied to the power supply line PIG, the states of the drivers DV2 and DV3 are checked to determine whether there is an abnormality. For example, the presence or absence of abnormality is identified for each item such as the bridge of the switching units U11 to U23, the motor coil open, and the motor coil short. When this processing is completed, the process proceeds to the next step S86, and the predetermined completion code 2 is transmitted to the electronic control unit 9 in the form of serial information via the interface IF3 and the signal line RXD. Then, the process returns to the main routine of FIG.

The microcomputer 1 operates in step S7.
After proceeding to step 6, it waits until it detects the reception of the completion code 2 from the servo unit SVU. After the microcomputer 8 executes step S86, the microcomputer 1 detects the reception of the completion code 2 in S76 and returns to the main routine of FIG.

The relay-3 can be shut off by controlling either of the microcomputers 1 and 8.
Since the micro computer 1 and the micro computer 8 are independent of each other, for example, when the micro computer 1 runs away or a reset signal is applied to it,
The state of the power supply line PIG is determined irrespective of the control state of the microcomputer 8. But in this example,
When diagnosing the apparatus, as shown in FIG. 12, the microcomputers 1 and 8 inform each other of the state by communication with each other, so that the microcomputer 8 correctly grasps the state of the power supply line PIG. It is possible, and there is no error in diagnosis.

The operation of the microcomputer 1 will be described with reference to FIG. 5 again. If the communication system is normal and the power system (relay, driver, electric motor) is also normal, the process proceeds through steps S12-S13 to S14, but if there is an abnormality in the communication system, the process proceeds from S12 to S1J. , If there is an abnormality in the power system, the process proceeds from S13 to S1H. In S1J, the diagnostic information indicating that the communication system is abnormal is stored in its own memory, and the diagnostic information is transmitted to the servo unit SVU using the signal lines RXD, TXD and CLK. S
At 1H, the diagnostic information indicating that the power system is abnormal is stored in its own memory, and the signal line RXD,
Using TXD and CLK to the servo unit SVU,
Send diagnostic information. Then, in the next step S1i, the signal level of the output port RLM is switched to the low level, and the relay-3 is turned off. As a result, the power supply to the power system power line PIG is cut off.

In the next step S14, the information of the parameters that determine the gain of the servo system is stored in the internal memory (ROM).
And read the information from the signal lines RXD, TXD, CL
Use K to send to servo unit SVU.

Next Steps S15-S16-S17-S
18-S19-S1A-S1B-S1C-S1D-S1
E-S1G-S15 -... Is repeatedly executed as a normal loop process. Further, this loop processing is basically periodically executed once every 5 msec. However, the cycle in which this loop processing is executed is not limited to 5 msec, regardless of the operation of the servo unit SVU,
There is no problem even if the cycle is changed as long as necessary.

Although not shown in FIG. 5, the electronic control unit 9 has other control system functions such as suspension control, vehicle speed control, brake control and transmission control.
Can be included in. However, when the microcomputer 1 executes such various controls, steps S15-S16-S17-S18-S19-S in FIG.
1A-S1B-S1C-S1D-S1E-S1G-S1
Since the loop processing corresponding to 5 -... Can not be executed in 5 msec, this control cycle is changed as necessary.

On the other hand, the servo unit SVU for controlling the electric motor for actually adjusting the steering angle is required to have a fast response, but if the control cycle of the servo unit SVU is lengthened, the response of the control system deteriorates. . Therefore, it is desirable to shorten the control cycle of the servo unit SVU as much as possible. Even if the electronic control unit 9 and the servo unit SVU have different control cycles, no problem occurs in this embodiment.

In step S15 of FIG. 5, the latest target steering angle T1 and its time differential value dT1 / dt are calculated, and the respective values are stored in a predetermined register.

In the next step S16, the variation ΔT of the target steering angle T1 during one calculation cycle (for example, 5 msec) is calculated. More precisely, the result of subtracting the content of the register holding the steering angle difference cumulative value Tθ from the latest target steering angle T1 is Δ.
Let T. The steering angle difference cumulative value Tθ is 0 in the initial state, and the change amount (ΔT) of the target steering angle T1 is added and updated every one calculation cycle (5 msec).

In step S17, the change Δ in the target steering angle is calculated.
T is compared with a predetermined upper limit value α. And ΔT> α
In the case of, the process proceeds to step S18, and ΔT is replaced with the upper limit value α. Therefore, the change amount ΔT of the target steering angle is limited to α or less.

In the next step S19, the steering angle difference cumulative value Tθ in which the latest target steering angle change ΔT is taken into consideration is determined.
That is, the result obtained by adding the latest ΔT to the previous Tθ is set as the steering angle difference cumulative value Tθ up to this time.

Change Δ in target rudder angle obtained in the above process
T and the time differential value dT1 / dt are associated with the steering angle of the rear wheel steering system, but in order for the servo unit SVU to control the rear wheel steering system, the drive amount of the motor (rack Information on the movement stroke of the shaft and the driving speed is required. Therefore, it is necessary to convert the unit from the steering angle to the drive amount. However, since the relationship between the steering angle and the movement stroke of the rack shaft is generally different for each vehicle type, it is necessary to change the calculation content of the unit conversion from the steering angle to the drive amount for each vehicle type. However, the unit conversion from steering angle to drive amount is
By executing the information inside the electronic control unit 9 and transmitting the converted information to the servo unit SVU, it is not necessary for the servo unit SVU to perform calculations that differ for each vehicle type, and all the servo units SVU are executed. It can be commonly used for all types of vehicles.

In this embodiment, in steps S1A and S1B executed by the electronic control unit 9, the unit conversion from the steering angle to the drive amount is executed. In step S1A, by substituting ΔT as a parameter into a predetermined function f1 (), the variation ΔT of the target drive amount of the motor is calculated.
Seeking 2 Further, in the next step S1B, the target drive speed VT1 of the motor is obtained by substituting dT1 / dt as a parameter into a predetermined function f2 ().

In the next step S1C, the information on the change amount ΔT2 of the target drive amount and the target drive speed VT1 is stored in the memories pre-allocated for data transmission. The information stored in the transmission memory is transmitted to the servo unit SVU in the form of serial binary data by executing a transmission / reception interrupt process (FIG. 8) described later. Further, in the next step S1D, the flag FT indicating the completion of the target value generation is set to 1.

In the next step S1E, the presence or absence of an abnormality in the servo unit SVU is identified. For example, when the microcomputer 1 detects an abnormality in the communication state, it is regarded as an abnormality in the servo unit SVU and the process proceeds to step S1F.
If there is no abnormality, the process proceeds to step S1G.

Normally, step S1F is not executed, but, for example, the microcomputer of the servo unit SVU goes out of control, the communication circuit fails, the driver is overheated, or the clock signal (CLK ), The process proceeds to step S1F. In the case of a runaway of the microcomputer or a failure of the communication circuit, the power supply relay-3 is shut off and the output of the communication clock signal (CLK) is stopped. However, when overheating of the driver is detected in the servo unit SVU, it is checked by referring to the status information from the SVU whether the servo unit SVU has completed the "neutral return control". ,
After waiting until the controller unit SVU completes the execution of the "neutral return control", step S1F is executed. Also at this time,
When the electronic control unit 9 is also used for control of a control system other than the rear wheel steering device, it is preferable that the power supply to the microcomputer 1 be continued.

In step S1G, whether or not the control period of 5 msec has elapsed is identified by referring to the timer interrupt, and when 5 msec has elapsed, the process returns to step S15 to repeat the above process.

Next, referring to FIG. 6, the servo unit SV
The operation of the U microcomputer 8 will be described. When the power source is turned on, the microcomputer 8 operates in step S2.
Initialize at 0. That is, the check of the CPU itself,
Memory clear, parameter initialization (including Tθ2 clear described later) and various mode sets are executed. Next, in step S21, the initial check described above is executed. In the actual diagnosis, the output port L
While sequentially switching the phase switching signals output to A1, LB1, LC1, LA2, LB2, LC2, the voltage levels input to the ports MI and PIGM of the microcomputer 8 are sampled and A / D converted. , And compare the entered value with a predetermined threshold,
State of relay-3, switching units U11, U1
The state of 2, U13, U21, U22 and U23, and the state of the coil of the electric motor 12 (open, short) are inspected for abnormality.

As a result of the inspection in step S21, when an abnormality in the communication system is detected, the process proceeds from step S22 to S26, and when an abnormality in the power system is detected, step S2 is executed.
It progresses from 3 to S26. In step S26, the phase switching signal output to the output ports LA1, LB1, LC1, LA2, LB2, LC2 is controlled to switch the switching unit U.
11, U12, U13, U21, U22, and U23 are all controlled to the off state, and the level of the signal line RLS is controlled to turn off the relay-3.

When there is no abnormality, steps S21-S2
2-Go through S23 to S24. In step S24, information (parameters that determine the gain of the servo system) transmitted from the electronic control unit 9 is input using the signal lines RXD, TXD, and CLK, and the servo system (Fig. (See 7)).

In the next step S25, the steering angle detector 21
The actual steering angle of the rear wheels detected by the magnetic pole counter (see Fig. 7)
Set to 87 as an initial value. Although the resolution of the detection value of the steering angle detector 21 is relatively low, the steering angle information with high resolution can be obtained by counting the pulses output by the magnetic pole sensor 18. However, since the steering angle information obtained by the magnetic pole sensor 18 is a relative change, first, the steering angle detector 2
The actual steering angle detected by 1 is adopted as an initial value, and the actual steering angle with high resolution obtained from this initial value and the change in the steering angle is generated by the magnetic pole counter 87.

Subsequent steps S27, S28, S29, S
2A, S2B, S2i, S2C, S2D, S2E, S2
F, S27, ... Are repeatedly executed as a loop process until some abnormality is detected. Further, this loop processing is periodically executed once every 5 msec.

First, in step S27, by referring to the timer interrupt, the process stands by until 5 msec has elapsed. When 5 msec has elapsed, the process proceeds to the next step S28, and stands by until the predetermined communication process is completed.

Communication processing is periodically carried out between the servo unit SVU and the electronic control unit 9, and the signal line R
Data is transmitted using XD, TXD and CLK.
The communication is processed by an interrupt process described later. Support from the electronic control unit 9 in one communication process
The data sent to the body unit SVU is the target drive amount ΔT.
2, the target drive speed VT1, the vehicle speed, and the status information of the unit 9 are included. Target drive amount ΔT
2. The target drive speed VT1, the vehicle speed, and the status information of the unit 9 are each 1-byte data, and the 4-byte data is transmitted from the electronic control unit 9 to the servo unit SVU in one communication. Is transmitted.

When the communication processing is completed, step S2
It progresses from 8 to S29. Steps S29, S2A, and S
2B, flags FE0, FE1, and FE2, respectively.
Check the condition of. The flag FE0 is used when the normal operation of the device is temporarily not guaranteed as when the engine is started.
It is temporarily set to 1 and 0 otherwise.
The flag FE1 is set to 1 when the microcomputer 8 determines that normal data communication with the electronic control unit 9 cannot be performed, and is set to 0 otherwise.
become. Further, the flag FE2 is set to 1 when an abnormality is detected in the communication processing, and becomes 0 otherwise. The flag FE1 is not set to 1 unless an error is continuously detected a plurality of times, but the flag FE2 is set to 1 when an error is detected even once, and the flag FE2 is returned to the normal state. Is cleared.

If the flag FE0 is 1, step S2
When the flag FE1 is 1, the process proceeds from step S2A to S2G. In step S2G, driving of the electric motor 12 is stopped (braking is applied), the state of the steering system of the rear wheels is fixed to the steering angle at that time, and the subsequent operation is stopped.

When both the flags FE0 and FE1 are 0, S2B is executed. Then, if the flag FE2 is 0, that is, if no communication abnormality has occurred, the process proceeds from step S2B to S2i and proceeds to S2C, but if FE2 is 1, the process proceeds to S2C without passing through S2i.

In step S2i, the content of the register holding the change amount ΔT2 of the target drive amount is updated by the data corresponding to ΔT2 in the receiving buffer holding the latest receiving data. In the next step S2C, the target drive amount Tθ2 in the servo unit SVU is updated by adding the change ΔT2 in the target drive amount to the target drive amount Tθ2.
Information on the target drive amount Tθ2 is held in a predetermined register.

When no communication abnormality has occurred, the target drive amount Tθ2 is updated by the latest reception data ΔT2. However, if a communication abnormality occurs and the flag FE2 is set, the servo unit on .DELTA.T2 is not updated, the target drive amount T.theta.2 is updated by the past data (.DELTA.T2) received before 5 msec. However, even if the flag FE2 is set, the steering control is continued.

In the next step S2D, the updated target drive amount Tθ2 is compared with the threshold value (upper limit value) Tmax.
If Tθ2 <Tmax, the process proceeds to step S2E. If not, "target drive amount abnormality" is stored in the memory as diagnostic information, and then the process proceeds to step S2G to enter the break mode.

In the next step S2E, the electric motor 12
The control of the servo system for driving is executed. The structure of this servo system is shown in FIG. The details of this servo system will be described later.

In the next step S2F, the overheat sensor OH
The signal output by S is referenced to identify whether the driver is in an overheated state. If it is normal, the process proceeds to step S27, but if the overheated state is detected, information indicating the state is stored in the memory as diagnostic information, and then the process proceeds to step S2H.

When the temperature of the motor driver (DV2, DV3) rises abnormally, the drive of the motor suddenly stops due to the activation of the protection circuit or the occurrence of a failure, and the control thereafter becomes impossible. is there. However, rather than the state where the steering position of the rear wheel steering mechanism is always deviated from neutral, it is easier to drive when the steering position is returned to neutral using some means. However, use of a mechanical element such as a return spring causes problems such as an increase in size of the device and an increase in manufacturing cost.

In this embodiment, the overheat of the driver is detected by the overheat sensor OHS before the temperature in the vicinity of the motor driver rises to a predetermined temperature at which the motor cannot be driven. In step S2H, the normal steering control is stopped and the drive of the motor 12 is controlled so that the steering position of the rear wheel steering mechanism returns to the neutral position. That is, the target position is changed to the neutral position of the steering mechanism, and the motor 12 is driven so as to approach the target position.

FIG. 7 shows a part of the processing of the electronic control unit 9 and the construction of the main part of the servo system of the servo unit SVU. This will be described with reference to FIG. Actually, all the control system shown in FIG. 7 except the motor driver 5, the electric motor 12, and the magnetic pole sensor 18 is a microcomputer.
It is realized by software processing of the computer 1 or the microcomputer 8. The motor driver 5 in FIG. 7 corresponds to the drivers DV2 and DV3 in FIG. The gain of this control system is set in step S24 in FIG.

The target steering angle T1 generated in the electronic control unit 9 is input to the subtracting section 101 corresponding to the above-mentioned step S16 and the differentiating section 102 corresponding to a part of S15. The subtraction unit 101 obtains and outputs the difference between the target steering angle T1 and the accumulated steering angle difference value Tθ, that is, the change ΔT of the target steering angle T1. The steering angle difference cumulative value Tθ is obtained by adding the latest variation ΔT to the cumulative value stored in the memory 103 up to the previous time in the adding unit 104 and writing the result in the memory 103. The differentiating unit 102 obtains and outputs a time differential value of the target steering angle T1, that is, dT1 / dt.
The conversion unit 105 corresponding to step S1A described above performs a calculation process for converting the unit of the input change ΔT of the target rudder angle T1 from the rudder angle to the motor drive amount (rack axis movement stroke). The calculation result ΔT2 is output. Further, in the conversion unit 106 corresponding to step S1B described above, the unit of the time differential value dT1 / dt of the target rudder angle that is input is calculated from the rudder angle to the motor drive amount (rack shaft moving stroke).
The calculation processing for converting into (1) is performed and the calculation result VT1 is output.

Information ΔT2 output by the electronic control unit 9
And VT1 are input to the servo unit SVU. Mode
The difference ΔT2 in the motor drive amount is accumulated in the adding unit 111 and the memory 112, and is converted into the motor drive amount Tθ2.
That is, the result obtained by adding the latest difference ΔT2 to the accumulated value stored in the memory 112 up to the previous time by the addition unit 111 is written in the memory 112 to obtain the motor drive amount Tθ2 corresponding to the target steering angle T1. To be In the following description, the motor drive amount Tθ2 will be referred to as the target steering angle for convenience.

The target steering angle Tθ2 is input to the subtracting section 92,
VT1 which is a time differential value of the target steering angle Tθ2 is input to the differential gain setting unit 91. The differential gain setting unit 91
The differential gain YTDIFGAIN is calculated from the absolute value of T1. The graph shown in each block of the differential gain setting unit 91 and the like shows the relationship between the input value and the output value, the horizontal axis shows the input value, and the vertical axis shows the output value. In this example, when the absolute value of the differential value VT1 is 4 deg / sec or less, the differential gain is 0 and the absolute value of the differential value SAGLA is 12 de.
The differential gain is set to 4 in the case of g / sec or more, and the differential gain becomes a value in the range of 0 to 4 in other cases.

The subtracting section 92 calculates the deviation between the target steering angle Tθ2 and the actual steering angle (corresponding to the motor rotation angle) RAGL, that is, the steering angle deviation ΔAGL. The actual steering angle RAGL is output from the magnetic pole counter 87. The magnetic pole counter 87 identifies the rotation direction of the electric motor 12 from the phase difference between the three-phase pulse signals output from the magnetic pole sensor 18, and adds or subtracts the pulse number of the pulse signal to the count value up to that point. Detect the rudder angle value. The steering angle value obtained by the pulse signal from the magnetic pole sensor 18 is a relative value (rotational angle), but in this example, first in step S25 of FIG. 6 (before starting driving).
The actual steering angle value detected by the steering angle detector 21 is set to the magnetic pole counter 87.
The value RAGL output from the magnetic pole counter 87 is the actual steering angle.

The steering angle deviation ΔAGL is processed by the steering angle deviation dead zone imparting section 93 and becomes the steering angle deviation value ETH2. The steering angle deviation dead zone applying unit 93 sets the steering angle deviation value ETH2 to 0 when the absolute value of the input value (steering angle deviation ΔAGL) is equal to or less than the predetermined value E2PMAX, and controls when the steering angle deviation ΔAGL is small. Is to stop. The steering angle deviation value ETH2 output by the steering angle deviation dead zone applying unit 93 is calculated by the proportional unit 9
6 and the differentiating unit 94.

The proportional portion 96 multiplies the steering angle deviation value ETH2 by a preset proportional gain value to obtain the proportional control value P.
Output as AGLA. The differentiating unit 94 determines the steering angle deviation value E
TH2 is differentiated with respect to time to obtain a steering angle deviation differential value SETH2. Further, in the multiplication unit 95, the result of multiplying the steering angle deviation differential value SETH2 by the above-mentioned differential gain YTDIFGAIN is obtained as the differential control value DAGLA. The addition unit 97 outputs the result of adding the proportional control value PAGELA and the differential control value DAGLA as the control steering angle value HPID.

The control steering angle value HPID passes through the steering angle deviation limiter 98 and becomes the control amount ANG. Steering angle deviation limiter 9
8 produces an output proportional to the input value and limits the range of the output value so that the controlled variable ANG does not become 1.5 deg or more or −1.5 deg or less. Controlled variable AN
The G is input to the pulse width modulation conversion unit 99 and converted into the pulse width modulation signal PWM1. That is, the pulse signal PWM1 having a constant cycle and a pulse width proportional to the control amount ANG is generated. The pulse width modulation signal PWM1 is input to the motor driver 5. The motor driver 5 determines the on / off timing of energization of the electric motor 12, that is, the current in accordance with the pulse width modulation signal PWM1. Therefore, the drive torque of the electric motor 12 changes according to the pulse width modulation signal PWM1. When the electric motor 12 rotates, the magnetic pole sensor 18 generates a pulse, so the magnetic pole counter 8
The count value of 7, that is, the actual steering angle value RAGL changes, and the steering angle deviation ΔAGL changes. This servo system has a steering angle deviation ΔAGL.
The electric motor 12 is controlled so that is close to zero.

However, when the break mode is set, the electric mode is set.
The control is performed so that the driving of the controller 12 is stopped early.
That is, a control signal is applied to the driver DV2 so as to brake the rotation of the electric motor 12.

FIG. 10 shows a timer interrupt process which the microcomputer 1 for controlling the electronic control unit 9 periodically executes every 5 msec. This process is S15-S of FIG.
It is executed by an interrupt while executing 1G loop processing. This will be described with reference to FIG.

In the first step S51, the power supply line D
The battery voltage appearing on the IG is transferred to the interface I
Sampling via F1, A / D conversion and reading,
This voltage VB is a predetermined threshold value (8V in this example)
Compare with If VB is greater than or equal to the threshold value, the process proceeds to step S52, and if not, the process proceeds to step S5B. Normally, the process proceeds from step S51 to step S52, but if the battery voltage drops abnormally, for example, when starting the engine, then step S5 is performed.
Go from 1 to S5B.

In step S52, timer T3 is set if it is not set. In step S5B, the timer T3 is cleared and its operation is stopped. In the next step S53, the timer T3 is referenced to check the elapsed time from when the detected battery voltage becomes normal. Normally, the process proceeds from step S53 to S54, but if the battery voltage abnormally drops and then returns to the normal voltage, the process proceeds from step S53 to S57 until 3 seconds elapses.

In step S54, it is determined whether or not the engine is rotating by referring to the engine rotation signal output from the terminal "L" of the regulator REG for stabilizing the voltage of the vehicle-mounted generator. If the engine is rotating, the process proceeds to step S55. If the engine is stopped, the process proceeds from S54 to S57.

In the next step S55, the state of a predetermined communication end flag is checked to see if the communication has ended. If the communication is completed, the process proceeds to step S56. If not completed, the process proceeds to step S58. Step S5
At 6, the state of the flag FE2 is checked to see if a reception abnormality has occurred. If FE2 = 1 (abnormal), the process proceeds to step S58, and if there is no abnormality, the process proceeds to step S57.

In step S58, the communication counter is incremented (+1), and in the next step S59, the value of the communication counter is compared with 3. If the communication counter is 3 or more, the process proceeds to the next step S5A, and the servo unit SVU is abnormal. Set a flag to indicate that there is one. Therefore, the servo unit SVU is considered to be abnormal in the following cases. When the communication end flag is not set while this timer interrupt occurs three times, that is, when the communication does not end even after 15 msec. When the communication process in which a reception error is detected continues three or more times.

Normally, the above steps S55, S56, S5 are performed.
Abnormality detection of S8, S59, S5A is executed, but when the battery voltage is abnormally low, such as when the engine is started, when 3 seconds have not passed since the battery voltage became normal, and when the engine is It is not executed when it is not rotating. Therefore, it is possible to prevent the abnormality from being erroneously detected when the function of the device is normal. In this embodiment, both the battery voltage and the presence / absence of engine rotation are monitored, but only one of them may be monitored. In step S57, the communication counter is cleared.

FIG. 11 shows a timer interrupt process which the microcomputer 8 for controlling the servo unit SVU periodically executes every 5 msec. This process is performed from S27 of FIG.
It is executed by an interrupt while the loop process of S2F is being executed. This will be described with reference to FIG.

In the first step S60, the electric motor 1
The output of the PWM (pulse width modulation) signal that determines the bias amount of 2 is executed. This process is 5msec due to the timer interruption
It is executed regularly every time.

In the next step S61, the state of a predetermined communication end flag is checked. If the communication end flag is set, the process proceeds to step S62, and if the communication end flag is not set, the process proceeds to step S69.

In the next step S62, data is transmitted from the servo unit SVU to the electronic control unit 9. The data transmitted here is the servo unit SVU.
The status information is 1 byte.

In the following step S63, the input port PI
The signal (battery-voltage) input to the GM is sampled, and the A / D converted voltage value VB is compared with the threshold value (8V). Then, when the detected battery voltage VB is equal to or higher than the threshold value, the process proceeds to step S64, but when the battery voltage is abnormally decreased, the process proceeds to step S6C. In this embodiment, the signal input to the input port PIGM is monitored, but the power supply line DIG may be used instead of the input port PIGM.

In step S64, timer T3B is set if it is not set. In step S6C, the timer T3 is cleared and its operation is stopped. In the next step S65, the timer T3B is referenced to check the elapsed time from when the detected battery voltage becomes normal. Normally, steps S65 to S66
If the battery voltage abnormally drops and then returns to the normal voltage, the process proceeds from step S65 to step S6E until 3 seconds elapses.

In step S66, whether or not the engine is rotating is identified by referring to the engine rotation signal output from the terminal "L" of the regulator REG for stabilizing the voltage of the vehicle-mounted generator. Then, if the engine is rotating, the process proceeds to step S6D, but if the engine is stopped, the process proceeds from step S66 to step S6E.

The flag FE0 is cleared in step S6D, and the flag FE0 is set in step S6E. After step S6D, the process proceeds to step S67, and after step S6E, the process proceeds to step S68.

In step S67, the state of the flag FE2 is checked to determine whether or not a reception error has occurred. If a reception error has occurred, the process proceeds to step S69, and if FE2 = 0, the process proceeds to step S68.

In step S69, the communication counter is incremented (+1), and in the next step S6A, the value of the communication counter is compared with 3. If the communication counter is 3 or more, the process proceeds to the next step S6B and the electronic control unit 9 is abnormal. A flag FE1 indicating that there is is set. Therefore, the electronic control unit 9 is considered to be abnormal in the following cases.
When the communication end flag is not set while this timer interrupt occurs three times, that is, when the communication does not end even after 15 msec. When the communication process in which a reception error is detected continues three or more times.

Normally, the above steps S61, S67, S6 are performed.
Abnormality detection of 9, S6A, S6B is executed, but when the battery voltage is abnormally low, such as when the engine is started, when 3 seconds have not passed since the battery voltage became normal, and when the engine is It is not executed when it is not rotating. Therefore, it is possible to prevent the abnormality from being erroneously detected when the function of the device is normal.

In step S68, the communication counter is cleared.

Electronic control unit 9 and servo unit SV
The data communication processing with U is performed by the servo unit SVU.
The microcomputer 8 is repeatedly activated at a cycle of 5 msec by executing step S62 of FIG. Then, when the data communication process is activated, communication is executed as follows.

By executing step S62 of FIG. 11,
A transmission interrupt request is issued to the microcomputer 8 of the servo unit SVU. When 1-byte data is transmitted from the servo unit SVU to the electronic control unit 9 by executing step S62, the electronic control unit 9
A reception interrupt request is issued to the microcomputer 1 of.
The microcomputer 8 of the servo unit SVU executes transmission / reception interrupt processing shown in FIG. 9 every time a transmission interrupt request or a reception interrupt request is generated. Further, the microcomputer 1 of the electronic control unit 9 executes the transmission / reception interrupt processing shown in FIG. 8 each time a reception interrupt request or a transmission interrupt request is generated.

When 1-byte data is transmitted from the servo unit SVU to the electronic control unit 9 by executing step S62, the microcomputer 1 of the electronic control unit 9 executes the transmission / reception interrupt processing shown in FIG. Then, the 1-byte data on the microcomputer 1 is transmitted to the servo unit SVU. By this data transmission, a transmission interrupt request is generated in the microcomputer 1 of the electronic control unit 9, and in response to the request, the microcomputer 1 again executes the transmission / reception interrupt processing of FIG. By repeating the transmission / reception interrupt process of FIG. 8, a plurality of bytes of data are transmitted from the electronic control unit 9 to the servo unit SVU in one communication process. When the transmission of all the data is completed, the communication process is completed.

Referring to FIG. 8, the microcomputer 1
The transmission / reception interrupt processing executed by will be described. In the first step S31, the interrupt request is identified as either a reception interrupt or a transmission interrupt by referring to the contents of the register of the interrupt circuit built in the microcomputer 1. In the case of a reception interrupt, the process proceeds from step S31 to S32, and in the case of a transmission interrupt, the process proceeds from step S31 to S38.

At the next step S32, the presence or absence of communication error is identified by referring to the contents of the register of the serial communication circuit built in the microcomputer 1. If there is no communication error, the process proceeds from step S32 to S33, and if there is a communication error, the process proceeds from step S32 to S35. Then, in step S33, the received 1-byte data is stored in a predetermined reception buffer (memory), the reception abnormality flag is cleared in subsequent step S34, and the process proceeds to the next step S36. Further, in step S35, the reception abnormality flag is set.

The communication end flag is cleared in step S36, and the transmission counter is cleared in subsequent step S37.

When the transmission counter is less than 3, the process proceeds from step S38 to S3A. When the transmission counter reaches 3, the process proceeds from step S38 to S39. Step S39
Then, the communication end flag is set. In step S3A, the contents of the transmission counter are referred to. When the transmission counter is 0 (when the data of the first byte is transmitted), the process proceeds from step S3A to S3B, otherwise, from step S3A. Proceed to S3E.

In step S3B, the state of the flag FT is referred to. If FT = 1, the process proceeds from step S3B to S3D, but if FT = 0, the process proceeds from S3B to S3C.
The flag FT is the step S of the main routine shown in FIG.
It is set to 1 when 1D is executed. Therefore, the loop processing in steps S15 to S1G of the main routine is temporarily performed.
If it is executed in msec, the flag FT will be set to 1 once every 5 msec. On the other hand, the communication processing is started at a rate of once every 5 msec by the timer interrupt of the microcomputer 8 of the servo unit SVU, and accordingly, step S3B of FIG. 8 is performed for 5 msec.
It is executed once every two times. Therefore, when the loop process of steps S15 to S1G of FIG. 5 is repeatedly executed at a constant cycle of 5 msec, the flag FT is always set to 1 when step S3B of FIG. 8 is executed. There is.

However, when the microcomputer 1 also executes a process (not shown) other than the steering control by adding the function, the loop process of steps S15 to S1G may not be executed within 5 msec. Occurs. In such a case, the target steering angle T1 in the electronic control unit 9 in response to the data request from the servo unit SVU.
The calculation processing such as is too late. However, from the electronic control unit 9 to the servo unit SVU, the target steering angle T
Since ΔT2 corresponding to the change ΔT of 1 is sent, when the calculation cycle of the electronic control unit 9 and the calculation cycle of the servo unit SVU are different, the target steering angle T of the electronic control unit 9 is changed.
1 may deviate from Tθ2 of the servo unit SVU. In order to prevent this deviation,
Steps S3B and S3C of FIG. 8 are executed.

That is, in response to a data request from the servo unit SVU, the target steering angle T in the electronic control unit 9
If the calculation process such as 1 is not in time, the flag FT is 0, and therefore the process proceeds from step S3B to step S3C in FIG. In step S3C, the values of ΔT2 and VT1 are both 0.
Then, ΔT2 and VT1 are stored in the memory for transmission. Therefore, in this case, .DELTA.T2 and VT1 transmitted from the servo unit SVU to the electronic control unit 9 become 0, so that a deviation occurs between the target steering angle T1 of the electronic control unit 9 and T.theta.2 of the servo unit SVU. Can be avoided.

The flag FT is cleared in step S3D.

In the next step S3E, 1 byte of data is transmitted to the servo unit SVU and the transmission counter is incremented (+1). In this embodiment, the data to be transmitted from the electronic control unit 9 to the servo unit SVU is the target drive amount ΔT2 and the target drive speed VT.
1, vehicle speed, and status information, which is 4 bytes in total. In step S3E, when the transmission counters are 0, 1, 2, and 3, the target drive amount ΔT
2, 1-byte data of the target drive speed VT1, vehicle speed, and status information is transmitted.

Next, the transmission / reception interrupt process executed by the microcomputer 8 will be described with reference to FIG.
In the first step S41, the state of the communication end flag is referred to. If the communication end flag is set, the process proceeds from step S41 to S48, and if the communication end flag is cleared, the process proceeds from step S41 to S42. Actually, when this process is executed in response to the transmission interrupt request generated immediately after the communication process is activated, the process proceeds to step S48.

At step S48, the microcomputer
The interrupt request identifies the reception interrupt or the transmission interrupt by referring to the contents of the register of the interrupt circuit built in the data processor 8. In the case of a transmission interrupt, step S48
From S49, the communication end flag is cleared and the reception counter is cleared.

On the other hand, when the data is received, the presence or absence of communication error is checked in step S42.
Actually, the presence or absence of communication error is identified by referring to the contents of the register of the serial communication circuit built in the microcomputer 1. Further, when the target drive amount ΔT2 is received, it is set to a predetermined maximum value β (α in S17 of FIG. 5).
(Corresponding to the above), when ΔT2> β, an error
Considered to occur.

If no communication error is detected,
The process proceeds from step S42 to S43. Then, in S43, the received 1-byte data is stored in a predetermined reception buffer (memory).
And the reception abnormality flag FE is stored in the next step S44.
Clear 2. When a communication error is detected, the process proceeds from step S42 to S4A, and the reception abnormality flag FE2
Set.

In the next step S45, the reception counter is incremented (+1), and in the subsequent step S46, the content of the reception counter is compared with 3. Then, when the reception counter = 3, the communication end flag is set.

Therefore, in the communication processing executed by the above-described interrupt processing, first, 1-byte status information is transmitted from the servo unit SVU to the electronic control unit 9, and then a response is sent thereto. Then, the 4-byte data is transmitted almost continuously from the electronic control unit 9 to the servo unit SVU, and one communication process is completed. This communication processing is performed every time a timer interrupt of the microcomputer 8 of the servo unit SVU occurs, that is, 5 m.
It is executed every sec. As long as there is no special abnormality, one communication process will be completed within 5 msec.

In the above embodiment, the target steering angle T
The information corresponding to the change ΔT of 1 is sent to the electronic control unit 9
The target steering angle T1 is transmitted from the electronic control unit 9 to the servo unit S.
It may be transmitted to the VU. In that case, the main routine of the microcomputer 1 of the electronic control unit 9 is shown in FIG.
3 and the main routine of the microcomputer 8 of the servo unit SVU may be changed to that of FIG. Further, the processes of steps S3B and S3C of FIG. 8 are omitted.

According to the embodiment described above, the following effects can be obtained.

(1) The timing at which the instruction value information (ΔT2, VT1) is transmitted from the first control means (9) to the second control means (SVU) is the instruction value request signal (SVU to electronic control unit). Data transmission to S9: S62 → reception interruption occurs in the electronic control unit 9). That is, regardless of the cycle of the processing cycle (S15 to S1G) repeatedly executed by the first control means, a fixed cycle (cycle of 5 msec timer interrupt in FIG. 11).
Then, the information of the indication value is transmitted from the first control means to the second control means. Therefore, it is not necessary to synchronize or make the cycle of the processing cycle repeatedly executed by the first control means and the cycle of the processing cycle repeatedly executed by the second control means. That is, in order to maintain the high responsiveness of the steering servo system, the first control means executes the processing cycle, while keeping the cycle of the processing cycle executed by the second control means short enough. The cycle of the processing cycle can be lengthened. Therefore, it becomes possible to centrally control various on-vehicle devices by the first control means including various functions other than the steering control. That is, when various on-board devices are mounted on an automobile, sharing the control unit not only reduces the number of control units but also significantly reduces wiring, which significantly reduces the manufacturing cost of the entire system. It can be reduced.

(2) Since the change amount (ΔT2) of the target steering angle is transmitted from the first control means (9) to the second control means (SVU), the information compared to the case where the target steering angle itself is transmitted. Since the number of bits of is reduced, the transmission speed can be reduced.
When the transmission rate is not changed, the required transmission time is shortened. Further, the processing executed by the first control means and the processing executed by the second control means are asynchronous, but the instruction value correction means (S3B, S3C) of the first control means is the second control means. When the calculation of the target rudder angle cannot be completed in time for the command value request signal from, the target rudder angle generated by the first control means is set to 0 as the command value and transmitted to the second control means. It is possible to reliably prevent the occurrence of a discrepancy with the target steering angle (accumulated value of change) grasped by the second control means.

(3) Since the change amount (ΔT) of the target steering angle transmitted from the first control means to the second control means is limited within a predetermined upper limit value (α), When the information received by the control means exceeds the upper limit value, it can be considered that an abnormality such as data error has occurred, and the malfunction is prevented by detecting the abnormality.

(4) In the second control means, the presence or absence of the first abnormality is identified by comparing the magnitude of the instruction value sent from the first control means with a predetermined upper limit value (S42, S4A). ), When the first abnormality is detected, the latest instruction value is invalidated and the instruction value received in the past is reused (S2B). By this control, abnormal steering control can be prevented and steering control can be continued, so even in an environment susceptible to noise,
Frequent outages of the device can be avoided.
If the first abnormality is repeatedly detected a predetermined number of times or more, normal operation is no longer guaranteed, so it is considered that the second abnormality has occurred (S6A, S6B), the driving means is braked, and automatic steering is performed. Since it is stopped (S2A, S2G), the occurrence of abnormal operation is reliably prevented.

(5) The second control means detects whether or not there is an abnormality in the instruction value sent from the first control means, and when the abnormality is detected, the predetermined abnormality processing is executed. Further, the power supply voltage of the second control means is detected, and when the detected power supply voltage is abnormal, the abnormality detection related to the indicated value is prohibited and the steering angle adjustment of the drive means is prohibited. When data error occurs in the instruction value sent from the first control means to the second control means due to the power supply voltage drop, the steering angle adjustment is only temporarily stopped, and after the engine is started. Normal rudder angle adjustment is performed. There is no fear that abnormal rudder angle adjustment will be performed.

(6) The second control means detects whether or not there is an abnormality in the instruction value sent from the first control means, and when the abnormality is detected, the predetermined abnormality processing is executed. In addition, it identifies whether the engine is operating or not, and when the engine is stopped, the detection of an abnormality related to the indicated value is prohibited and the steering angle adjustment of the drive means is prohibited. If the decrease causes a data error in the instruction value sent from the first control means to the second control means, the steering angle adjustment is only temporarily stopped and the normal value is set after the engine is started. The rudder angle is adjusted. There is no fear that abnormal rudder angle adjustment will be performed.

(7) Since the power supply connected to the drive means (12) can be turned on / off by the switching means (3), for example, when the microcomputer of the second control means runs out of control. It is safe because the first control means can control the switching means to cut off the power supply of the driving means. In addition, the diagnostic mode (S11,
In S21), the power supply control means (S11, S71 to S76) of the first control means controls the switching means, and at the same time transmits information indicating the state of the switching means to the second control means. Then, the failure detection means (S21, S81 to S86) of the second control means inputs the information transmitted from the first control means, identifies the state of the switching means, and detects the state of the switching means. The presence or absence of a failure is diagnosed based on the state of the driver that controls the energization of the drive means. Therefore, the second control means can surely know the state of the switching means, and therefore can make a correct diagnosis when diagnosing the driver circuit or the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a steering system of an automobile of an embodiment.

FIG. 2 is a partially cutaway plan view showing the outer appearance of the rear wheel steering mechanism 11 of FIG.

3 is a block diagram showing a configuration of an electronic control unit 9 of FIG.

FIG. 4 is a block diagram showing a configuration of the servo unit SVU shown in FIG.

5 is a flowchart showing the operation of the microcomputer 1 of FIG.

6 is a flowchart showing the operation of the microcomputer 8 of FIG.

FIG. 7 is a block diagram showing a configuration of a servo system according to an embodiment.

FIG. 8 is a flowchart showing a transmission / reception interrupt process of the electronic control unit 9.

FIG. 9 is a flowchart showing transmission / reception interrupt processing of the servo unit SVU.

FIG. 10 is a flowchart showing a timer interrupt process of the electronic control unit 9.

FIG. 11 is a flowchart showing timer interrupt processing of the servo unit SVU.

FIG. 12: Electronic control unit 9 and servo unit SV
It is a flowchart showing the contents of the initial check of U.

FIG. 13 is a flowchart showing a main routine of an electronic control unit 9 in a modified embodiment.

FIG. 14 is a servo unit SVU in a modified embodiment.
It is a flowchart showing the main routine of.

[Explanation of symbols]

1: Microcomputer 2: Battery 3: Relay 4: Power supply unit 6: Voltage monitoring circuit 8: Microcomputer 9: Electronic control unit 10: Front wheel steering mechanism 10a: Rack shaft 11: Rear wheel steering mechanism 12 : Electric motor (brushless motor) 13: Left front wheel 14: Right front wheel 15: Left rear wheel 16: Right rear wheel 17,20: Steering angle detector 18: Magnetic pole sensor 19: Steering wheel 21: Rudder Angle detector 22, 23: Vehicle speed detector 24: Yaw rate detector 25: Rack shaft 71: Power supply unit 87: Magnetic pole counter G1: And gate DV1, DV2, DV3: Driver IF1, IF2, IF3: Interface -Face IG: Ignition switch DIG, PIG: Power line SVU: Servo unit OHS: Overheat sensor TS: Thermistor SCK: Black Click stop detection circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Katsuraya 2-1-1 Asahi-cho, Kariya city, Aichi Prefecture Aisin Seiki Co., Ltd.

Claims (9)

[Claims] 1. A sensor means for detecting information on a vehicle state; a first digital processor, which is connected to the sensor means, repeatedly calculates a target steering angle based on the information detected by the sensor means, and calculates the target rudder angle. First control means for transmitting information according to the selected target steering angle as an instruction value; driving means for adjusting the steering angle; and a second digital processor independent of the first digital processor, A vehicle including second control means for inputting information on an instruction value transmitted by the first control means, and adjusting the urging amount of the drive means based on the instruction value and the state quantity of the control target steering system. In the steering control device, signal generating means for sending an instruction value request signal from the second control means to the first control means in a substantially constant cycle; and the first value control means in response to the instruction value request signal. Control means To the second control means, the transmission control means for sending the information of the instruction value; and the steering control device for the vehicle. 2. The first control means includes a change amount calculation means for generating, as the instruction value, information corresponding to the calculated change amount of the target steering angle, and the second control means includes the first change amount calculation means.
Further includes cumulative value calculating means for calculating a cumulative value of the indicated values sent from the control means, and the first control means includes the second
The instruction value correction means for transmitting 0 to the second control means as an instruction value when the calculation of the target steering angle is not in time for the instruction value request signal from the control means of 1. Vehicle steering control device. 3. The first control means includes means for comparing the calculated change amount of the target rudder angle with a predetermined upper limit value, and the upper limit of the instruction value to be transmitted to the second control means. 3. The method according to claim 2, further comprising limiter means for limiting the value within a value.
The vehicle steering control device described. 4. The means for identifying the presence or absence of a first abnormality by comparing the magnitude of the instruction value sent from the first control means with a predetermined upper limit value, and the first control means. Means for invalidating the latest indication value when the abnormality is detected, and reusing the indication value received in the past, and means for detecting the second abnormality when the first abnormality is repeatedly detected a plurality of times. , And a steering control device for the vehicle according to claim 2, further comprising means for braking the drive means when a second abnormality is detected. 5. The second control means carries out a predetermined abnormality processing when the abnormality is detected by the abnormality detection means for detecting an abnormality in the indication value sent from the first control means. The means, the means for detecting the power supply voltage of the second control means, and the detection prohibition means for prohibiting the abnormality detection of the abnormality detection means when the power supply voltage of the second control means is abnormal. Vehicle steering control device. 6. The vehicle steering control according to claim 5, wherein the second control means includes means for prohibiting the steering angle adjustment of the drive means when the power supply voltage of the second control means is abnormal. apparatus. 7. The second control means carries out a predetermined abnormality processing when an abnormality is detected by the abnormality detection means for detecting an abnormality in the indication value sent from the first control means. 2. The vehicle steering control device according to claim 1, further comprising: a means, a means for identifying whether or not the engine is operating, and a detection inhibiting means for inhibiting the abnormality detection of the abnormality detecting means when the engine is stopped. . 8. The vehicle steering control device according to claim 7, wherein the second control means includes means for prohibiting a steering angle adjustment of the drive means when the engine is stopped. 9. A sensor means for detecting information relating to a vehicle state; including a first digital processor, connected to the sensor means, and repeatedly calculating and calculating a target steering angle based on the information detected by the sensor means. First control means for transmitting information according to the selected target steering angle as an instruction value; driving means for adjusting the steering angle; and a second digital processor independent of the first digital processor, A vehicle including second control means for inputting information on an instruction value transmitted by the first control means, and adjusting the urging amount of the drive means based on the instruction value and the state quantity of the control target steering system. In the steering control device, a switching means provided in the first control means for switching on / off of a power source connected to the drive means; a predetermined diagnostic mode provided in the first control means In the power source control means, controlling the switching means, and transmitting information indicating the state of the switching means to the second control means.
And the second control means, and in the diagnostic mode, inputs the information transmitted from the first control means to identify the state of the switching means, and the state of the switching means, A steering control device for a vehicle, comprising: failure detection means for diagnosing the presence or absence of a failure based on the state of a driver that controls the energization of the drive means.