JP3837317B2 - Vehicle steering system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering apparatus configured to drive a steering mechanism that has no mechanical coupling to an operation member such as a steering wheel to steer steering wheels.
[0002]
[Prior art]
The mechanical connection between the steering wheel and the steering mechanism for steering the steering wheel is eliminated, and the steering wheel operation direction and operation amount are detected. On the basis of the detection result, the steering mechanism is steered by an electric motor or the like. A vehicle steering device (so-called steer-by-wire system) in which a driving force from an actuator is applied has been proposed.
[0003]
By adopting such a configuration, it is possible to freely change the ratio (gear ratio) between the rotation amount of the steering wheel and the steering wheel according to the traveling state of the vehicle, and the movement of the vehicle. The performance can be improved. In addition, the configuration as described above also has an advantage that the steering wheel can be prevented from being pushed up at the time of a collision, and an advantage that the degree of freedom of the arrangement position of the steering wheel is increased.
FIG. 2 is a block diagram showing an electrical configuration of the steer-by-wire system. Detection signals such as an operation direction and an operation amount of the steering wheel are input to a main control electronic control unit (ECU) 101. A main steering motor 105 and a sub steering motor 106 are coupled to the steering mechanism, and a reaction force motor 107 is coupled to the steering wheel. Both the main steering motor 105 and the auxiliary steering motor 106 are for applying a driving force to the steering mechanism to cause the steering wheels to steer, but the auxiliary steering motor 106 is the main steering motor 105 and its control. When abnormality occurs in the system or the like, it operates so as to give a driving force to the steering mechanism. The reaction force motor 107 applies a reaction force corresponding to the road surface reaction force to the steering wheel.
[0004]
The main steering motor 105 is driven and controlled by the main steering electronic control unit 102. Specifically, the main steering electronic control unit 102 includes a main steering drive unit 108 that supplies a drive current to the main steering motor 105, and a main steering control unit 111 that controls the main steering drive unit 108.
The auxiliary steering motor 106 is driven and controlled by the auxiliary steering electronic control unit 103. Specifically, the secondary steering electronic control unit 103 includes a secondary steering drive unit 109 that supplies a drive current to the secondary steering motor 106 and a secondary steering control unit 112 that controls the secondary steering drive unit 109.
[0005]
Similarly, the reaction force motor 107 is driven and controlled by the reaction force electronic control unit 104. The reaction force electronic control unit 104 includes a reaction force drive unit 110 that supplies a drive current to the reaction force motor 107, and And a reaction force control unit 113 that controls the reaction force drive unit.
The main steering driving unit 108, the auxiliary steering driving unit 109, and the reaction force driving unit 110 are driver circuits including power elements, and the main steering control unit 111, the auxiliary steering control unit 112, and the reaction force control unit 113 are current feedback control. Control commands for each are output. The main steering control unit 111, the auxiliary steering control unit 112, and the reaction force control unit 113 are integrated and controlled by the main control electronic control unit 101.
[0006]
[Problems to be solved by the invention]
However, in the above-described configuration, four electronic control units 101 to 104 and a harness for passing signals between them are required, so the configuration is complicated and the cost is high.
In addition, since the number of electronic control units and the number of harnesses are large, it is necessary to design the entire system in consideration of various failure modes. This makes the system design difficult and costly. It was a factor.
[0007]
On the other hand, sensor signals necessary for controlling the main steering motor 105, the auxiliary steering motor 106 and the reaction force motor 107 are input to the main control electronic control unit 101. When the main control electronic control unit 101 fails, the power is cut off and the sensor signal is given to the main steering electronic control unit 102 and the like.
However, since the main steering electronic control unit 102 only performs basic control such as current feedback control, the main steering electronic control unit 102 cannot always properly control the steering mechanism. Therefore, the control function is limited.
[0008]
Further, the main steering electronic control unit 102 has a function of supplying a large current to the main steering motor 105, so that a failure is likely to occur. If a failure occurs in the main steering electronic control unit 102, the sub steering electronic control unit 103 The steering mechanism is driven by the controlled auxiliary steering motor 106. However, since the auxiliary steering motor 106 is usually inferior in function to the main steering motor 105, it is inevitable that the function is restricted. In particular, when a failure occurs in the main control electronic control unit 101 and the main steering electronic control unit 102, a large function restriction is imposed.
[0009]
Further, the power supply to the main control electronic control unit 101 when a failure occurs is performed by its own processing. From the main steering electronic control unit 102 or the auxiliary steering electronic control unit 103, the main control electronic control unit 103 is turned off. 101 cannot be powered off. Therefore, if the main control electronic control unit 101 runs away and the power supply is not shut off, the main steering motor 105 may cause an unintended operation.
[0010]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vehicle steering apparatus that solves the above technical problem and can stably control the steering mechanism even when a failure occurs in the main control unit.
[0011]
[Means for Solving the Problems and Effects of the Invention]
In order to achieve the above object, the invention according to claim 1 is characterized in that the operating member (30) for steering the vehicle and the operating member are provided in a mechanically uncoupled state to rotate the steering wheel. A steering mechanism (10) for steering, a main steering actuator (51M) for applying a driving force to the steering mechanism, a reaction force actuator (40) for applying a reaction force corresponding to a road surface reaction force to the operation member, and the above A sub-steering actuator (51S) for applying a driving force to the steering mechanism when a main steering drive system (50M) including the main steering actuator fails, a main steering control unit (61M) for feedback control of the main steering actuator, reaction force control section for feedback controlling the reaction force actuator (45), the auxiliary steering control for feedback controlling the auxiliary steering actuator And (61S), sensors (41,42,52M, 52S, 15,70) based on an input signal from, required for each feedback control in the main steering control unit, the reaction force control unit and the auxiliary steering controller First feedback control in the main steering control unit, reaction force control unit, and auxiliary steering control unit based on input signals from the first main control unit (81) for performing overall control including processing and the sensors And a second main control unit (82 ) for performing overall control including processing necessary for the above, the main steering control unit, the reaction force control unit, and the auxiliary steering control unit include the first main control unit And the second main control unit, and the first main control unit and the main steering control unit are integrated into the first electronic control unit (U1). The second main control And the reaction force control section, the is integrated into the second electronic control unit that performs mutual monitoring of abnormality (U2) between the first electronic control unit, the auxiliary steering control unit, the third The vehicle steering device is provided in the electronic control unit (U3) . The alphanumeric characters in parentheses indicate corresponding components in the embodiments described later. The same applies hereinafter.
[0012]
According to the above configuration, the first main control unit and the main steering control unit are integrated in the first electronic control unit, and the second main control unit and the reaction force control unit are integrated in the second electronic control unit. Integrated. Then, the first and second electronic control units mutually monitor the occurrence of abnormality. Thus, for example, even if an abnormality occurs in the main control unit of one electronic control unit, the main steering control unit and the reaction force control unit can be comprehensively controlled by the main control unit of the other electronic control unit. Therefore, even if a failure occurs in one of the main control units, the function is not limited, and the steering mechanism can be controlled stably.
[0013]
In addition, the first main control unit and the main steering control unit are integrated into the first electronic control unit, and the second main control unit and the reaction force control unit are integrated into the second electronic control unit, so that the electronic control The number of units can be reduced. Accordingly, the harness between the electronic control units can be reduced, and the failure mode can be reduced. This simplifies the configuration and contributes to cost reduction.
[0014]
Further, in the first electronic control unit, it is possible to perform mutual monitoring of the occurrence of abnormality between the first main control unit and the main steering control unit. Accordingly, when an abnormality occurs in the first main control unit, an unintended operation of the steering mechanism can be avoided by driving the main steering actuator based on the same control command value as that immediately before the occurrence of the abnormality, for example. The same applies to the second electronic control unit.
In the first electronic control unit, when a failure occurs in the first main control unit, at least a part of the functions can be replaced by the main steering control unit. As a result, even if an abnormality occurs in the first main control unit, it is not necessary to shut off the power supply of the first electronic control unit, so a sensor signal or the like given from the first main control unit to another control unit, etc. There is no sudden change in the level, and no abnormal control is performed.
[0015]
When a failure occurs in both the first and second main control units, limited control may be performed by the main steering control unit and the reaction force control unit .
[0016]
In the present invention, when the main steering drive system fails, a driving force is applied to the steering mechanism by the auxiliary steering actuator. In this case, even if a failure occurs simultaneously in either of the first and second main control units, the sub steering control unit controls the sub steering actuator while receiving overall control of any normal main control unit. it can. Therefore, there are few function restrictions and a steering mechanism can be controlled favorably.
The third electronic control unit may monitor occurrence of abnormality in the first and second electronic control units. For example, when both the first and second main control units fail and the main steering drive system also fails simultaneously, the sub steering control unit independently controls the sub steering actuator to steer. The mechanism may be driven. Thereby, the safety | security of the steering device for vehicles can be improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram for explaining a basic configuration of a vehicle steering apparatus according to an embodiment of the present invention. The vehicle steering device is provided with a steering mechanism 10 for causing a pair of steering wheels (usually front wheels) W and W to perform a steering operation, and without mechanical coupling to the steering mechanism 10. And a steering wheel 30.
[0018]
In this vehicle steering apparatus, a steering drive system for driving the steering mechanism 10 is a dual system of a main steering drive system 50M and a sub steering drive system 50S. The main steering drive system 50M includes a main steering actuator 51M and a main rotation angle sensor 52M for detecting the rotation angle of the main steering actuator 51M. On the other hand, the sub steering drive system 50S includes a sub steering actuator 51S and a sub rotation angle sensor 52S for detecting the rotation angle of the sub steering actuator 51S. Each of the main steering actuator 51M and the sub steering actuator 51S is constituted by, for example, an electric motor.
[0019]
The steering mechanism 10 includes a steering shaft 11 that extends in the left-right direction of the vehicle body, a knuckle arm 13 that is coupled to both ends of the steering shaft 11 via tie rods 12 and 12 and supports the steering wheels W and W. 13. The steering shaft 11 is supported by the housing 14 and is slidable in the axial direction, and a main steering actuator 51M is coaxially incorporated in the middle portion thereof.
A rack gear 11a is formed on a part of the steering shaft 11, and a pinion gear 22 at the tip of the shaft 21 is engaged with the rack gear 11a. A sub steering actuator 51S is coupled to the shaft 21, and a driving force generated by the sub steering actuator 51S is input to the shaft 21.
[0020]
With this configuration, when the main steering actuator 51M is driven, the rotation of the main steering actuator 51M is converted into sliding of the steering shaft 11 by a motion conversion mechanism made of a ball screw or the like. W, W steering is achieved. When the auxiliary steering actuator 51S is driven, the rotation of the shaft 21 by the auxiliary steering actuator 51S is converted into sliding of the steering shaft 11 by the pinion gear 22 and the rack gear 11a, and the steering wheels W, W steering is achieved.
[0021]
A reaction force actuator 40 for applying a reaction force corresponding to a road surface reaction force to the steering wheel 30 is coupled to the steering wheel 30.
The reaction force actuator 40 is constituted by an electric motor (for example, a three-phase brushless motor) having a shaft 23 coupled to the steering wheel 30 as a rotation axis, and a casing thereof is fixed at an appropriate position of the vehicle body. The reaction force actuator 40 is provided with a torque sensor 41 for detecting the steering torque input from the steering wheel 30 and an operation angle sensor 42 for detecting the operation angle of the steering wheel 30.
[0022]
The reaction force actuator 40, the main steering actuator 51M, and the auxiliary steering actuator 51S are supplied with drive current from drive circuits 43, 53M, and 53S.
The detection signals of the torque sensor 41, the operation angle sensor 42, the main rotation angle sensor 52M, and the sub rotation angle sensor 52S are input in common to the first and second electronic control units (ECU) U1 and U2. Further, a steering position sensor 15 for detecting the axial position of the steering shaft 11 is provided in association with the steering shaft 11, and the detection signal of the steering position sensor 15 is also the first and second detection signals. A common input is made to the electronic control units U1, U2. Further, a detection signal of a vehicle speed sensor 70 for detecting the vehicle speed is input in common to the first and second electronic control units U1, U2. The vehicle speed sensor 70 can be constituted by, for example, a wheel speed sensor that detects the rotational speed of a wheel.
[0023]
The first electronic control unit U1 includes a main steering control unit 61M for giving a control signal to a drive circuit (main steering drive circuit) 53M for the main steering actuator 51M and current feedback control of the main steering actuator 51M, and the whole The unit has a first main control unit 81 for overall control. Thereby, the number of electronic control units is reduced, and the number of harnesses is reduced accordingly. Thereby, cost can be reduced and the number of failure modes such as disconnection failure of the harness can be reduced.
[0024]
The main steering control unit 61M and the first main control unit 81 are each provided with a CPU (central processing unit) and monitor each other's operation. When an abnormality occurs in the operation of one of the control units, the operation of the control unit in which the abnormality has occurred is taken over by the other normal control unit. Therefore, for example, even if an abnormality occurs in the first main control unit 81, it is not necessary to shut off the power supply of the first electronic control unit U1.
[0025]
The second electronic control unit U2 includes a reaction force control unit 45 for giving a control signal to a drive circuit (reaction force drive circuit) 43 for the reaction force actuator 40 and performing current feedback control of the reaction force actuator 40, and the whole. The unit has a second main control unit 82 for overall control. As a result, the number of electronic control units and the number of harnesses are reduced, thereby reducing the cost and the number of failure modes.
[0026]
Each of the reaction force control unit 45 and the second main control unit 82 includes a CPU and monitors each other's operation. When an abnormality occurs in the operation of one of the control units, the operation of the control unit in which the abnormality has occurred is taken over by the other normal control unit. Therefore, for example, even if an abnormality occurs in the second main control unit 81, it is not necessary to shut off the power supply of the second electronic control unit U2. A third electronic control unit U3 is provided for current feedback control of the auxiliary steering actuator 51S. The third electronic control unit U3 provides a drive circuit (sub-steering drive circuit) 53S for the sub-steering actuator 51S, and gives a control signal to the sub-steering driving circuit 53S to perform current feedback control of the sub-steering actuator 51S. The auxiliary steering control unit 61S is included in the unit. The auxiliary steering control unit 61S includes a CPU.
[0027]
The first and second main control units 81 and 82 are based on input signals from the sensors 41, 42, 52M, 52S, 15, and 70, respectively, and the main steering control unit 61M, the auxiliary steering control unit 61S, and Overall control including processing necessary for each current feedback control in the reaction force control unit 45 can be executed . The main steering control unit 61M, the auxiliary steering control unit 61S, and the reaction force control unit 45 are comprehensively controlled by one of the first and second main control units 81 and 82.
The first and second electronic control units U1 and U2 monitor the operation of each other, and when an abnormality occurs in one of the first and second main control units 81 and 82, The main control unit performs overall control of the main steering control unit 61M, the auxiliary steering control unit 61S, and the reaction force control unit 45. Therefore, even when an abnormality occurs in one main control unit, the steering mechanism 10 can be satisfactorily controlled without being restricted in function.
[0028]
When an abnormality occurs in both the first and second main control units 81 and 82, this is detected by the main steering control unit 61M and the reaction force control unit 45, respectively. The main steering control unit 61M and the reaction force control unit 45 independently control the main steering actuator 51M and the reaction force actuator 40 without depending on the first or second main control unit 81 or 82. It will be. For example, if the control command immediately before the occurrence of an abnormality is maintained, an unintended operation of the steering mechanism 10 due to an abnormal signal from the first or second main control unit 81 or 82 can be prevented.
[0029]
The third electronic control unit U3 monitors the operations of the first and second main control units 81 and 82 in the first and second electronic control units U1 and U2. When an abnormality occurs in any of the main steering control unit 61M, the main steering drive circuit 53M, and the main steering actuator 51M (that is, when an abnormality occurs in the main steering drive system 50M), the first or second main control unit. The sub steering actuator 51S is driven and controlled while receiving overall control by 81, 82 (that is, one of the first and second main control units 81, 82) . Therefore, control with few function restrictions is possible.
[0030]
When a failure occurs in the main steering drive system 50M, if an abnormality occurs in both the first and second main control units 81 and 82, the sub steering control unit 61S does not depend on these, The steering actuator 51S is controlled.
As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form. For example, the harness can be reduced by integrating the main steering drive circuit 53M into the first electronic control unit U1 or the main steering actuator 51M. Similarly, the reaction force drive circuit 43 may be integrated with the second electronic control unit U2 or may be integrated with the reaction force actuator 40. Further, the third electronic control unit U3 may be integrated with the auxiliary steering actuator 51S.
[0031]
In the above-described embodiment, the example in which the steering wheel 30 is used as the operation member has been described. However, other operation members such as a lever may be used.
In addition, various design changes can be made within the scope of matters described in the claims.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram for explaining the configuration of a vehicle steering apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram for explaining a configuration of a vehicle steering apparatus according to a conventional technique.
[Explanation of symbols]
10 steering mechanism 30 steering wheel 40 reaction force actuator 43 reaction force drive circuit 45 reaction force control unit 50M main steering drive system 50S sub steering drive system 51M main steering actuator 51S sub steering actuator 53M main steering drive circuit 53S sub steering drive circuit 61M main Steering control unit 61S Sub steering control unit 81 First main control unit 82 Second main control unit U1 First electronic control unit U2 Second electronic control unit U3 Third electronic control unit W Steering wheel

Claims (1)

An operating member for steering the vehicle;
This operating member is provided in a mechanically unconnected state, and a steering mechanism for turning the steering wheel,
A main steering actuator for applying a driving force to the steering mechanism;
A reaction force actuator for applying a reaction force corresponding to the road surface reaction force to the operation member;
A sub-steering actuator that applies driving force to the steering mechanism when a main steering drive system including the main steering actuator fails;
A main steering control unit for feedback control of the main steering actuator;
A reaction force control unit for feedback control of the reaction force actuator;
A secondary steering control unit for feedback control of the secondary steering actuator;
A first main control unit for performing overall control including processing necessary for each feedback control in the main steering control unit , reaction force control unit, and sub-steering control unit based on input signals from sensors ;
A second main control unit for performing overall control including processing necessary for each feedback control in the main steering control unit, reaction force control unit, and sub-steering control unit based on input signals from the sensors ; Including
The main steering control unit, the reaction force control unit, and the auxiliary steering control unit are configured to be comprehensively controlled by any one of the first main control unit and the second main control unit,
The first main control unit and the main steering control unit are integrated in a first electronic control unit;
The second main control unit and the reaction force control unit are integrated with a second electronic control unit that performs mutual monitoring of occurrence of abnormality with the first electronic control unit ,
The vehicle steering apparatus , wherein the auxiliary steering control unit is provided in a third electronic control unit .

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