JPH01218971A - Electrically driven power steering control device - Google Patents

Abstract

PURPOSE:To prevent a control from generating a time delay by controlling steering assist force by an analog circuit. CONSTITUTION:A torque sensor signal T and a steering angle sensor signal thetaare respectively input to a microcomputer 1 and a multiplier part 2. The signals T, theta, input to the multiplier part, branch respectively with one signal fed to multipliers 6, 7 passing through compensators 4, 5 and the other signal directly fed to multipliers 8, 9. In the microcomputer 1, a signal value, which is to be fed to the multipliers 6-9 in accordance with a running condition of a vehicle, is calculated by signals T, S and a car speed signal V, and the calculated result is fed to the multipliers 6-9 through latches 10-13. An output of the multipliers 6-9 is added in an adder 15 and fed to a power circuit 3. The power circuit 3 controls a motor 18, obtaining assist steering force.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electric power steering control device, and more particularly to an electric power steering control device that uses a motor to assist the steering force of an automobile, etc. and provides an excellent steering feel. .

[Conventional technology]

A power steering device needs to change the steering assist force depending on the vehicle speed in order to improve the steering feeling and ensure safety. However, when the gain of the control circuit is increased to improve the feel, vibrations occur.

As a solution to these problems, for example,
0780, Japanese Patent Laid-Open No. 60-35664, etc., but fine control is difficult. Therefore, recently, control by microcontrollers has become more common.

This shows that microcomputer control is effective not only for improving the feel of the vehicle, but also as a safety measure against abnormal conditions such as failures.

However, simply replacing part of the conventional control circuit with a microcomputer does not allow the microcomputer to process calculations according to the output signal of the torque sensor and the output signal of the steering angle sensor.
Since the power circuit is driven only by the microcomputer output, a time delay occurs in the control system and self-excited vibration occurs.

This self-excited vibration is not only felt through the handle, but also
The entire car body vibrates minutely, creating noise inside the car.

In particular, this problem becomes more likely to occur when the compensation section gain is increased in an attempt to improve responsiveness. If the signal processing speed of the microcomputer is increased, self-excited vibration becomes less likely to occur, but because there is a limit to processing speed, self-excited vibration cannot be completely prevented.

[Problem to be solved by the invention]

In a conventional control device using a microcomputer, a time delay occurs in the control system, which causes self-excited vibration. Therefore, conventionally, self-excited vibrations are prevented at the expense of the responsiveness of the control system.

An object of the present invention is to provide an electric power steering control device that can prevent self-excited vibrations in an electric power steering control system, improve responsiveness, and apply steering assist force according to vehicle speed, steering angle, etc. It is in.

[Means to solve the problem]

The above object is to provide an electric power steering control device having a steering data detection means, a calculation control means for performing calculation control based on the steering data, and a power circuit for driving and controlling a motor based on the output from the calculation control means. This is achieved by providing gain adjustment means that inputs an analog signal from the data detection means, adjusts the gain according to the output signal from the arithmetic control means, and outputs a control signal to the power circuit.

[Effect]

The steering data detection means outputs sensor signals from various sensors, the arithmetic control means inputs the sensor signals and outputs control signals, and the gain adjustment means converts the analog signal from the steering data detection means into the arithmetic control means. The gain is adjusted according to a control signal from the gain adjusting means, and the power circuit drives the motor based on the output from the gain adjusting means. Therefore, in the control using the analog signal, self-excited vibration does not occur even if the gain is increased to improve responsiveness.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 shows a microcomputer 12 multiplier section 2. This section shows the overall configuration of the control circuit of the electric power steering control device including the power circuit 3. This control circuit has a basic configuration that drives the power circuit 3 using a torque sensor signal T, a steering angle sensor signal θ, and a vehicle speed signal V. If there are any other necessary signals, they can be input to the microcomputer 1.

One of each of T and θ is input to the microcomputer 1, and the - one is sent to the multiplier section 2. The vehicle speed signal V is sent only to the microcomputer. The signals T and θ sent to the multiplier section 2 are each branched, and one is sent to the multipliers 6 and 7 through compensators 4 and 5,
The other is sent directly to multipliers 8,9. In the microcomputer, the multiplier 6,
The signal values to be sent to the multipliers 6, 7° 8.
I am sending it to 9th. For example, when driving at high speeds, the gain of the control system is reduced, or arithmetic processing is performed so that negative feedback partially proportional to the steering angle is applied in order to obtain the restoring force of the steering. The decoder 14 selects which multiplier the calculation result of the microcomputer 1 is sent to. The outputs of multipliers 6.7 and 8.9 are added together in adder 15 and sent to power circuit 3.

In the power circuit 3, since the current detection signal 17 of the remoter 18 is negatively fed back by the differential amplifier 16, the output signal of the multiplier section 2 is amplified without passing an excessive current to the motor 18. It is sent to PWM 19 and comparator 20. The output of the differential amplifier 16 is
If the value is higher than a certain reference value and it is determined that the motor 18 should be rotated in the normal direction, the AND circuit 21. is activated and amplifier 2
2 to turn on the forward rotation transistor 23. In the case of reversal, the AND circuit 24 operates and turns on the reversing transistor 26 through the amplifier 25.

FIG. 2 is a diagram showing a circuit example of the multipliers 6, 7, 8.9 in FIG. 1. Resistor 2 connected to operational amplifier 27
The resistance values from 8 to 32 are R22R, 4R, 8R, 16
If R, the analog signal can be amplified in 16 ways by opening and closing the switch 33 in response to the digital signal. That is, this multiplier can change the gain of the analog signal using the digital signal. Comparing with FIG. 1, the digital signal is
．． The analog signal is the T, θ signal or the output signal of the compensator 4.5. Differential circuits are used as compensators to improve responsiveness and stabilize control systems, but in this case self-excited vibrations tend to occur in high frequency regions. In particular, when directly controlled by a microcomputer, a one-hour delay (phase delay) occurs, resulting in self-excited vibration. In this embodiment, the high frequency range is processed by analog, and the low frequency range, such as vehicle speed V, is processed by the microcomputer, so self-excited vibration can be prevented.

FIG. 3 is an example of a circuit diagram of a DA converter.

To realize the embodiment of FIG. 1, four DA converters are required. The circuit diagram shown in FIG. 3 realizes this with one DA converter.

In FIG. 3, T and θ are each (7), while 4:1. FE
T34.35 is sent to the drain terminal, and the other is sent to the compensator 4.
5 to the drain terminals of FETs 36 and 37. The signals from the microcomputer are sent to hold circuits 41 to 44 via the DA converter 38 by opening and closing the switch 40 by the decoder 39, and are sent to the gate ends of the FETs 34 to 37, respectively.

The source terminals of FETs 34 to 37 are connected to operational amplifiers 45 to 4.
8, and the output of each operational amplifier is sent to an adder. Although four switches 4o can be opened and closed at the same time, normally they are opened and closed one at a time, and the output signal of the DA converter is sent to each hold circuit in turn.

Here, one each of FETs 34 to 37 and operational amplifiers 45 to 48 are combined to form a multiplier.

This is a multiplier that utilizes the fact that the resistance between the drain and source of the FET changes depending on the gate voltage.

Since there are multipliers other than those shown in FIG. 3, they may be replaced with the ones shown in FIG. 3 in consideration of price and characteristics.

〔Effect of the invention〕

According to the present invention, since the steering assist force is controlled by an analog circuit, there is no time lag, and therefore the occurrence of self-excited vibration can be prevented. Furthermore, since automatic excitation does not occur, the gain can be increased and the steering assist force can be controlled with high responsiveness.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall structure of a control circuit of an electric power steering control device according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of the circuit of the multiplier shown in FIG. 1, and FIG. FIG. 2 is a diagram showing an example of a multiplier used in FIG. 1...Microcomputer, 3...Power circuit, 6-9...
Multiplier, 18... Motor, T... Torque sensor signal, θ... Rudder angle sensor signal, ■... Vehicle speed sensor signal.

Claims (1)

[Claims] 1. An electric power steering control device having a steering data detection means, a calculation control means for performing calculation control based on the steering data, and a power circuit for driving and controlling a motor based on the output from the calculation control means. , further comprising gain adjustment means for inputting an analog signal from the steering data detection means, adjusting the gain according to the output signal from the arithmetic control means, and outputting a control signal to the power circuit. Electric power steering control device. 2. The electric power steering according to claim 1, wherein the steering data is a torque sensor signal, a steering angle sensor signal, and a vehicle speed sensor signal, and the analog signal is the torque sensor signal and the steering angle sensor signal. Control device.