JPH02171385A - Power steering device - Google Patents

Abstract

PURPOSE:To obtain an assist quantity corresponding to temperature in a simple manner by executing power steering by use of fussy operation processing, and thereby eliminating a need for a converting table converting steering signals based on temperature, and the like. CONSTITUTION:Outputs from a torque sensor 2 and a temperature sensor 5 are transferred to fussy reasoning sections 21-1 through 21-25 wherein fussy reasoning is performed in accordance with specified rules so that its outputs are transferred to a fussy defining section 22. In the fussy defining section 22, the maximum value of each output section is computed based on outputs in series so that the fussy defined value is obtained based on the centroid value of those outputs. The output signal from the defined value is applied to a steering motor 7 as a drive signal via a motor drive section 23. The motor drive section 23 drives the steering motor 7 toward the output direction of the torque sensor 2 depending on given manipulated variables.

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]

As shown in Japanese Patent Application Laid-Open No. 59-156863, a conventional electric power steering motor drive device has a first motor drive device that is electrically connected when steering in the left and right directions. 2nd and 3rd. A bridge connection is made around the steering motor using a control element such as a fourth transistor. When steering to the right, the first control is performed based on the detection of the steering torque. The second control element is made conductive at the same time to supply a positive driving current to the motor, and when steering to the left, the third control element is turned on based on the detection of the steering torque. The fourth control element is made conductive at the same time to flow a drive current in the opposite direction to the motor to rotate the motor forward and reverse, respectively, thereby controlling the steering.

[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 model, the higher the temperature inside the vehicle, the faster the reaction speed of humans, and the lower the temperature, the slower the reaction speed. Further, the rated upper limit value of the control element of the controller also changes depending on the temperature. Therefore, it is preferable to reduce assist l-ff1 when the temperature is high, and increase assist ffi when the temperature is low. In order to change the assist amount in this way, it is necessary to provide a torque table in the memory that converts the output obtained from the torque sensor in correspondence with each temperature, or to perform conversion processing on the torque signal. Therefore, the more detailed the torque values and temperatures are, the larger the number of tables becomes, and the processing becomes more complicated.

The present invention has been made in view of the problems of conventional power steering devices, and has a relatively hour wheel configuration that can control the amount of assist by changing it based on torque and temperature inside the vehicle. 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 steering sensor that outputs a signal indicating the operating direction of the steering wheel of the vehicle, a temperature sensor that detects the temperature inside the vehicle, and a steering sensor. and a plurality of fuzzy inference units that input signals obtained from the temperature sensor, change the amount of assist in response to the steering signal according to predetermined rules, and perform fuzzy inference to vary the amount of change depending on the temperature. , a determining unit that obtains a non-fuzzy determined value based on the parallel outputs of the respective fuzzy inference 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.
It is characterized by having the following.

[Effect]

According to the present invention having such characteristics, signals from a steering sensor and a temperature sensor that output signals indicating the operating direction of the steering wheel are provided to a plurality of fuzzy inference units,
Fuzzy operations are performed.

Therefore, by creating predetermined fuzzy inference rules in advance such that the assist amount is changed in accordance with the steering signal and the amount of change is made different depending on the temperature, fuzzy inference based on each rule is executed. Then, the output from each fuzzy inference section is given to the determining section to determine the non-fuzzy assist 1-ffi. Power steering is realized by operating the steering wheel in a predetermined direction based on this assist amount.

(Effects 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 the steering signal based on the temperature.
Therefore, even if torque and temperature are subdivided, it does not become a complicated table, and the assist f that corresponds to temperature with a relatively simple configuration
The effect is that it is possible to realize power steering that provides fi.

[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 motor drive circuit 4. Further, the output of a temperature sensor 5 that detects the temperature inside the vehicle is given to the motor drive circuit 4. The motor drive circuit 4 is connected to a battery 6 of the vehicle, and controls a steering motor 7 that drives left and right in response to a left and right torque signal given from a torque sensor 2. Together with the mechanism 3, the steering wheel 8 is rotated by a predetermined angle in the left-right direction.

Next, the configuration of the motor drive circuit 4 will be explained with reference to FIG. In the present invention, signals from the torque sensor 2 that detects the drive torque of the steering shaft and the temperature sensor 5 are used to determine the assist amount of the power steering. That is, the output of the torque sensor 2 and the output of the temperature sensor 5 are transmitted to a plurality of fuzzy inference units 21-1 to 21-25, 25 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 and temperature signal, as will be described later, and their outputs are transmitted to the fuzzy determination unit 22. 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 7 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 7 in the output direction of the torque sensor 2 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 has a membership function generation circuit (M
FC) and a Meversyssop function generator (M F
G> is provided. In this embodiment, the torque input state is divided into the following five states using the Maber-Sissop function.

To: No torque input TNM:) There is a little bit of input. T1: With torque input Tpt:) Slightly large torque input TPM: l” large torque input In addition, the temperature input status is divided into the following five types.

θNM: Minimum temperature input θN7: Temperature input is slightly low θ. ,: Optimal temperature input θ, T: Temperature input is slightly high θrM: Maximum temperature input Furthermore, the assist output is divided into the following five types.

Io = No assist output INN Near assist output slightly small I sr Near assist output part Torque input to,
The membership function of temperature input and assist output is used. Next, the fuzzy inference units 21-1 to 21-25 will be explained. Each fuzzy inference unit is MFC31-1 to 31-2
5, 32-1 to 32-25. MFC3
1-1 and 32-1 are generation circuits (MFC) that generate membership functions corresponding to, for example, To and 08M;
Each output is given to a MIN circuit 33-1. Also midfielder
G34-1 is a membership function generator (MFG) that generates a parallel membership function of the assist output shown in FIG.
given to. MIN circuit 35-1 is MIN circuit 33-
1 to generate a smaller parallel fuzzy signal, and the output is given to the MAX array circuit 36.

Next, FIG. 4 shows an inference rule table determined based on these inputs. This inference rule is shown as follows, for example.

(Rule 1) If the torque input (x) is To and the temperature input (y) is θ, set the assist output (z) to 10.

This rule 1 is simplified and expressed as follows.

If x=To and y=θss then z
= I.

Similarly, each rule is determined as shown in the table of FIG. For example (Rule 2) If X = TNM and V = θ
N7 then Z = r si These rules change the assist amount to increase as the torque signal increases, and the amount of change is made to vary depending on the temperature. In this way, 25 inference rules are defined as shown in FIG. These outputs are provided to MAX array circuit 36. The MAX array circuit 36 calculates the maximum value for each corresponding parallel line, and its parallel output is given to the defassifier circuit 37. The defassifier circuit 37 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.

Also, a temperature signal is always obtained from the temperature sensor 5 while the vehicle is running. These signals are given to each of the fuzzy inference sections 21-1 to 21-25 as described above, and the signals T0 to TPM and θM□ to θPM are outputted by the respective MFCs. For example, as shown in FIGS. 3(a) and 3(b), the torque input X is a predetermined value X, T□=0.3, TNa=
0.7, and the input y from the temperature sensor 5 is a predetermined value y, and as shown in the figure, θ9 is 0.8. θ. □=0
．． When a value of 2 is obtained, the MFC of the fuzzy inference section
A corresponding output is obtained, and the MIN circuit 33 outputs a signal with a smaller value.

For example, TNM, θNt-IN? =0.3T)I
MI θ0T−I NM = 0.2TNa, θN?
−1rt = 0.7 T, ↑・ θOd −I Hd = 0.2 Therefore, fuzzy parallel horns are obtained from 4 of the 25 fuzzy inferences, and these outputs are M.A.
A MAX operation is performed by the X array circuit 36. As a result, as shown in FIG. 5, an output as shown by the broken line of the assist output Maber-Sissop function is obtained. The differential assist circuit 37 calculates the assist ff1Z+ by calculating the center of gravity of this signal. This assist amount is given to the motor drive section 23. Motor drive section 2
3 drives the steering motor 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 and temperature, and steering is performed accordingly.

Further, although this embodiment describes a power steering device that performs fuzzy inference according to the MIN-MAX calculation rule, the present invention can also be realized by fuzzy inference according to other calculation rules. Furthermore, fuzzy processing can be performed not only by specialized devices for fuzzy inference (e.g., Nikkei Electronics, July 28, 1987, pp. 148-152, 9 Nikkei McGraw-Hill), but also by binary devices programmed to perform fuzzy inference. It can also be realized by a type of computer, Brosefza, etc. Further, the membership function is not limited to the triangular shape shown in FIG. 3, but may be of any shape. Further, membership functions and inference rules can be changed or modified as appropriate depending on control results, etc.

Further, in this embodiment, a torque signal is used in addition to the temperature sensor as an input, but in addition to or instead of this, the amount of operation from the steering wheel, such as an angle signal and the amount of change in the angle, that is, the angular velocity value It is also possible to perform fuzzy control based on the amount of assistance.

Furthermore, although this embodiment describes an electric power steering device, the present invention can also be configured to operate a motor-hydraulic power steering mechanism according to the calculated assist amount.

[Brief explanation of the drawing]

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 (a) is the membership function of torque human power. Figure 3 (bl is the Mevership function of temperature input, Figure 3 (C1 is the figure showing the Mevership function of assist output,
FIG. 4 is a graph summarizing the rules for fuzzy inference, and FIG. 5 is a graph showing a calculation process for the center of gravity of the assist output obtained based on a predetermined torque input and temperature input. ■・・−・−・Steering handle 2・−−−
--) Lux sensor 3--・--conduction mechanism 4--
−・−Motor drive circuit 5−・・・−・Temperature sensor
7--Steering motor 21-1~2 22--Determination section 2 1-1~31-25.32 33-1~33-25.3 Circuit 34-1~34 MAX array circuit child circuit 1 -25-----Fuzzy inference section 3...Motor drive section 3 1~32-25-...MFC 5-1~35-25=--M I N25-----
--M F G 3637------- Defuzzify patent applicant Tateishi Electric Co., Ltd. agent Patent attorney Yoshiki Okamoto (and one other person) Figure (a) Figure (b) Figure (C) (2 Fig.

Claims (1)

[Claims] (1) A power steering device that performs a steering operation of a vehicle based on an input signal, comprising: a steering sensor that outputs a signal indicating the operating direction of the steering wheel of the vehicle; a temperature sensor that detects the temperature inside the vehicle; and the steering wheel. A plurality of fuzzy inferences that take signals obtained from the sensor and the temperature sensor as input, change the amount of assist in response to the steering signal according to predetermined rules, and perform fuzzy inference that changes the amount of change depending on the temperature. 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 characterized by: