JPH02290777A - Power steering device - Google Patents

Abstract

PURPOSE:To obtain a desired assistance quantity by the simple constitution by obviating the need of a table for converting the steering torque of a steering wheel on the basis of the angle and the angular speed, by executing power steering by utilizing the fuzzy calculation processing. CONSTITUTION:The torque, angle, and angular speed in the steering direction of a steering wheel are detected by sensors 2, 5, and 6, and these outputs are inputted into a plurality of fuzzy inference parts 21-1-21-63. In each fuzzy inference part 21, fuzzy inference is carried out so that the assistance quantity is increased according to the increase of the torque and the angular speed, in conformity with a previously determined rule, and the assistance quantity in the reverse direction to the steering wheel angle is generated in close to the torque of zero. Then, in a determination part 22, the nonfuzzy determined value is obtained on the basis of the parallel output of each fuzzy inference part 21, and in an operation part 23, the assistance quantity for operating the steering wheel in a prescribed direction is outputted on the basis of the output of the determination part 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a power steering device that performs power steering using fuzzy control.

[Conventional technology]

Conventional electric power steering motor drive devices are as shown in Japanese Patent Application Laid-Open No. 156863/1983.
1st, 2nd and 3rd conductive, respectively, when steering in left and right directions.
, a fourth transistor, and other control elements are connected in a bridge around the steering motor. When steering to the right, the first control is performed based on the detection of the steering torque. The second control Jlu element is made conductive at the same time to flow a driving current in the forward direction to the motor, and when steering to the left, the third and fourth control elements are simultaneously made conductive based on the detection of the steering torque to drive the motor in the reverse direction. Steering is controlled by applying current to rotate the motors forward and reverse, respectively.

[Problem to be solved by the invention]

However, in such a conventional power steering device, the steering torque and the current flowing through the steering motor, that is, the steering assist force, have an almost one-to-one correspondence. However, even in vehicles of the same type, when the steering wheel is turned quickly, a sufficient amount of assist is required, and when the steering wheel is returned to its original position, it is preferable to control the amount of assist so as to hasten the return. In order to change the amount of assist in this way, it is necessary to create a torque table in memory that converts the output obtained from the torque sensor using signals such as steering wheel angle and steering wheel angular velocity, and to perform torque signal conversion processing. . Therefore, the more detailed the torque value, the angular velocity value of the steering wheel, and the angle value are, the more the number of tables becomes larger, and the processing becomes more complicated.

The present invention has been made in view of the problems of conventional power steering devices, and is capable of controlling the amount of assist by changing it based on the torque and the angular velocity and angle of the steering wheel with a relatively simple configuration. The technical challenge is to do so.

[Means to solve the problem]

The present invention is a power steering device that performs a steering operation of a vehicle based on an input signal, and includes a torque sensor that outputs a torque signal in the operating direction of the steering wheel of the vehicle, and an angular velocity that detects the angular velocity in the operating direction of the steering wheel of the vehicle. A sensor, an angle sensor that detects the angle of the operating direction of the vehicle's steering wheel, a torque sensor, an angular velocity sensor, and signals obtained from the angle sensor are used as human power to provide assistance in response to increases in the torque signal according to predetermined rules. a plurality of fuzzy inference units that perform fuzzy inference to increase the assist amount in the direction corresponding to the angular velocity, and change the assist amount in the direction opposite to the steering wheel angle near the torque signal to be zero; The present invention is characterized by having a determining section that obtains a non-fuzzy determined value based on the parallel outputs of the respective fuzzy inference sections, and an operating section that outputs an assist amount for operating the steering wheel in a predetermined direction based on the output of the determining section. It is something.

[Effect]

According to the present invention having such characteristics, signals from the torque sensor outputting a torque signal of the steering wheel, the angular velocity sensor, and the angle sensor are given to a plurality of fuzzy inference units, and fuzzy calculations are executed. Therefore, the assist amount is changed in accordance with the torque signal, and the assist amount is increased in the direction corresponding to the steering wheel angular velocity, and when the torque signal is near zero, the assist amount is set in the opposite direction to the steering wheel angle. By creating fuzzy inference rules, fuzzy inference is executed based on each rule. Then, the output from each fuzzy inference section is given to the determining section to determine the non-fuzzy assist 1. Power steering is realized by operating the steering wheel in a predetermined direction based on this assist amount.

〔Effect of the invention〕

Therefore, according to the present invention, by executing power steering using fuzzy calculation processing, there is no need to provide a conversion table or the like for converting a torque signal based on a signal from a steering wheel angular velocity sensor or an angle sensor, resulting in a relatively simple configuration. The effect is that it is possible to realize power steering that provides a desired amount of assist.

[Explanation of Examples]

FIG. 2 is a schematic diagram of a power steering mechanism to which the present invention is applied, and FIG. 1 is a block diagram showing the overall configuration of its motor drive circuit. In FIG. 2, a torque sensor 2 and a transmission mechanism 3 for transmitting a steering force from the steering handle 1 are connected to the steering handle 1. The torque sensor 2 detects the torque of the steering wheel 1 in the left and right direction, and its output is given to the fuzzy controller 4. Further, a steering wheel angle sensor 5 is provided on the shaft of the steering wheel 1 to detect its angle, and its output is given to a fuzzy controller 4 and a differentiation circuit 6. The differentiating circuit 6 differentiates the steering wheel angle signal to obtain a steering wheel angular velocity signal, and its output is given to the fuzzy controller 4. The fuzzy controller 4 is connected to the van terry 7 of the vehicle, and controls the steering motor 8 that drives in the left-right direction based on the outputs of the torque sensor 2, the angle sensor 5, and the differential circuit 6. The steering wheel 9 is rotated by a predetermined angle in the left-right direction.

Here, the steering wheel angle sensor 5 and the differential circuit 6 constitute an angular velocity sensor that detects the angular velocity of the steering wheel.

Next, the configuration of the fuzzy controller 4 will be explained with reference to FIG. In the present invention, a signal obtained by differentiating the output signal of the torque sensor 2 that detects the drive torque of the steering shaft, the output signal of the steering wheel angle sensor, and the output of the steering wheel angle 5 is used to determine the amount of power steering assist. That is, the outputs of the torque sensor 2, differential circuit 6, and angle sensor 5 are transmitted to a plurality of fuzzy inference units 21-1 to 21-63, 63 in this embodiment, as shown in FIG. These fuzzy inference units are inference units that perform fuzzy inference according to predetermined rules based on the torque signal, steering wheel angular velocity signal, and angle signal, as will be described later, and their outputs are transmitted to the fuzzy determination unit 22 with errors. The fuzzy determining section 22 calculates the maximum value of each output section based on the parallel outputs obtained from each fuzzy inference section. Then, fuzzy definite values are obtained based on the centroid values of those outputs. This output is then given to the steering motor 8 as a drive signal via the motor drive section 23. The steering motor drive section 23 is an operation section that drives the steering motor 8 according to a given operation amount.

Next, the configurations of the fuzzy inference section and determination section that perform fuzzy processing will be further explained. As shown in the figure, each fuzzy inference section includes a membership function generation circuit (MFC) that generates a membership function corresponding to the input torque signal, steering wheel angular velocity, and steering wheel angle signal, and a membership function corresponding to the amount of assist to be output. A membership function generator (MFG) is provided to generate a membership function generator (MFG). Now, in this embodiment, the torque input state is expressed as a third
The angular velocity of the handle and the handle angle are divided into three states as shown in Figure 3(b) and (C).Here, NL is a negative NM is a medium negative value, NS is a small negative value, ZR is almost zero, PS is a small positive value, PM is a medium positive value, and PL is a large positive value. In addition, P and M show positive and negative values, respectively. Also, the Maber-Sissob function of the assist force is also N as shown in Figure 3 (d+).
It is assumed that L-PL is divided into seven states.

Next, the fuzzy inference units 21-1 to 21-63 will be explained. Each fuzzy inference unit has three MFC31-1~
3 1-63. 3 2-1 to 3 2-63.
3 3-1 to 33-63. The fuzzy inference unit 21-1 is an inference unit that performs the inference of Rule 1, which will be described later. This is a generation circuit (MFC) that generates P and ZR, and each output is connected to the MIN circuit 34.
−1 is given. Further, the MFG 35-1 is a MFG function generator (MFG) that generates a parallel MFG function PL as an assist output shown in FIG. 3(d), and its parallel output is given to the MIN circuit 36-1. The MIN circuit 36-1 generates a smaller parallel fuzzy signal by comparing it with the output of the MIN circuit 34-1, and its output is given to the MAX array circuit 37.

Next, the inference rules determined based on these inputs are shown below.

(Rule 1) If the torque input (SL) is PL, the angular velocity human power (S2) from the differential circuit 6 is P, and the input (s3) from the steering wheel angle sensor 5 is ZR, then the assist output (E) is P.
Let's call it L.

This rule 1 is simplified and expressed as follows.

If SL=PL and S2=P and
S3=ZRLhenPL Such a rule is that the larger the signal from the torque sensor 2, the larger the assist amount, and if the steering angular velocity is in the positive direction, the assist output will also be in the positive direction, and if the angular velocity is in the negative direction, the assist output will also be large in the negative direction. I'm trying to make it happen. Further, when the torque signal is close to zero, the assist amount is changed in the direction opposite to the direction of the steering wheel angle.

When the output from the steering wheel angle sensor 5 is ZH, the assist output E is shown in Table 1 below with respect to the output S1 from the torque sensor 2 and the angular velocity human power S2.

If the output from the steering wheel angle sensor 5 is P, the assist force rules for inputs Sl and S2 are shown in Table 1 below.

Table 2 Furthermore, when the output S3 from the steering wheel angle sensor is N, the assist force (E) with respect to the inputs Sl and S2 is shown in Table 3 below.

Table 3 In this way, 63 inference rules are determined, and the parallel fuzzy output which is the inference result of each rule is sent to the fuzzy inference unit 21.
-1 to 21-63. These outputs are MAX
The signal is applied to array circuit 37. The MAX array circuit 37 calculates the maximum value for each corresponding parallel line, and its parallel output is given to the defuzzifier circuit 38. The defuzzifier circuit 38 obtains a non-fuzzy output by calculating the center of gravity of its output, and the output is given to the motor drive section 23, which is an operating section.

Next, the operation of this embodiment will be explained. When the driver operates the steering wheel, a torque signal is obtained from the torque sensor 2 in response to the operation.

Further, as the steering wheel l rotates, the differential circuit 6 and the angle sensor 5 generate an angular velocity signal S2 and a steering wheel angle signal S.
3 is obtained. These signals are given to each fuzzy inference section 21-1 to 21-63 as described above, and the NL-PL or NP signal is outputted by each MFC. For example, as shown in FIG. 3 (al~(Cl), the torque input 81 is a predetermined value S1, PS=0.7, PM=0.
3, and the angular velocity 82 is a predetermined value S2.

and Z R =0.8, P =0.2,
Also, the handle angle 33 is a predetermined value S3. And ZR=0.
6. In the case of N=0.4, the MF of the fuzzy inference part
A corresponding output is obtained from C, and a signal with a smaller value is output from the MIN concave path 34. In this case, the rules corresponding to the outputs of Tables 1 and 2 of the above-mentioned Tables 1 to 3 are applied. That is, from Table 1, the assist output E is as follows.

P L =0.2, PM=0.3, PM=
0.2. P S =0.6 Also, from Table 2, the assist output is obtained as follows.

P L=0.2, PM=0.3, PM=0
．． 2, P S = 0.4 Therefore, fuzzy parallel outputs are obtained from eight of the 63 fuzzy inference units, and these outputs are subjected to MAX calculation by the MAX array circuit 37 of the determining unit 22. As a result, the fourth
As shown in the figure, out of the membership function of the assist output, the output shown by the broken line is obtained. The defuzzifier circuit 38 calculates the assist IEl by calculating the center of gravity of this signal.

This assist amount is given to the motor drive section 23.

The motor drive unit 23 drives the steering motor 8 based on the amount of assist given in the operating direction of the torque sensor 2 . In this way, the amount of steering operation is calculated based on the torque, steering wheel angular velocity, and steering wheel angle, and steering is performed accordingly.In addition, this embodiment uses a power controller that performs fuzzy inference according to the MIN-MAX calculation rule. Although a steering system is described, the invention can also be implemented by fuzzy reasoning according to other calculation rules. Furthermore, fuzzy processing is carried out using dedicated devices for fuzzy inference (for example, Nikkei Electronics, July 28, 1987, pp. 148-1).
52 pages. It can be realized not only by a computer (Nikkei McGraw-Hill, Inc.), but also by a binary type computer, processor, etc. that is programmed to execute fuzzy computation. Further, the makeship function is not limited to a triangular shape as shown in FIG. 4, but may be of any shape. For example, the assist force can be calculated by assuming that the membership function of the assist output has a right-angled triangular shape as shown in FIG. Furthermore, the server function and the inference rules can be changed or modified as appropriate depending on the control results and the like.

Although this embodiment describes an electric power steering device, the present invention can also operate a hydraulic power steering mechanism based on the calculated assist 1.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an electric power steering device according to an embodiment of the present invention, FIG. 2 is a schematic diagram of an electric power steering mechanism to which the power steering device according to this embodiment is applied, and FIG. 3 (al is the makership function of the torque sword, Fig. 3 (b) is the mebership function of the angular velocity of the handle, Fig. 3 (C) is the mebership function of the handle angle, Fig. 3 (dl is the makership function of the assist output) Fig. 4 is a graph showing the calculation process of the center of gravity of the assist output obtained based on a predetermined torque input, angular velocity input, and angle input, and Fig. 5 shows an example of another Mever-Syssop function of the assist output. FIG.
...MFC 34; 36...Yu-. M
I N circuit 35...1 MFG 37-...
MAX array circuit 3 8------Defuzz fire circuit patent applicant Tateishi Electric Co., Ltd. agent Patent attorney Yoshiki Okamoto (and one other person) 1--------Steering handle 2...Torque sensor 3 -... - Conduction mechanism 4 - Fuzzy controller 5 - - Steering wheel angle sensor 6 - Differential circuit 8 - - Steering motor 2Ll ~ 2 1 -63 - - - −
Fuzzy inference section 22...One song Figure 2---11 Tono l-'7t sensor 5------Hand-shaped sensor Diagram (a) Figure (b) Figure (C) Diagram

Claims (1)

[Claims] (1) A power steering device that performs steering operation of a vehicle based on an input signal, which includes a torque sensor that outputs a torque signal in the operating direction of the vehicle's steering wheel, and detects the angular velocity in the operating direction of the vehicle's steering wheel. An angular velocity sensor, an angle sensor that detects the angle in the operating direction of the steering wheel of the vehicle, and signals obtained from the torque sensor, angular velocity sensor, and angle sensor as input, and respond to increases in the torque signal according to predetermined rules. multiple fuzzy inference units that perform fuzzy inference to increase the assist amount in the direction corresponding to the angular velocity, and change the assist amount in the direction opposite to the steering wheel angle near the torque signal zero. and a determining unit that obtains a non-fuzzy determined value based on the parallel outputs of the respective fuzzy reasoning units; and an operating unit that outputs an assist amount for operating the steering wheel in a predetermined direction based on the output of the determining unit. A power steering device featuring: