JPH0428586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electric power steering control device, and particularly to providing an electric power steering control device suitable for use in general passenger cars and the like.

[Background of the invention]

A conventional electric power steering control device requires a voltage value (or resistance value, or current value) representing the neutral point of a torque sensor and a steering angle sensor, as seen in Japanese Patent Laid-Open No. 59-171759. No consideration was given to the means for converting the mechanical neutral point into an electrical position, and when it was actually installed in a product, there was a problem in that it took time to make adjustments.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electric power steering control device that improves the matching between a torque sensor and a steering angle sensor attached to a vehicle and a control device.

[Summary of the invention]

The present invention resides in that the mechanical neutral points of the torque sensor and steering angle sensor are electrically set on the control device side, thereby making it possible to easily set the neutral points of the sensors of the electric power steering device.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. When the driver applies steering force to the steering wheel 1,
Torque sensor 2 detects steering force transmitted to shaft 3. This can be considered by inserting a strain gauge or a torsion spring mechanism into the shaft 3, and detecting the amount of deflection of this spring with a volume or the like. This steering force is transmitted to the tires 6 via the rack 4 and pinion 5, and the tires 6 are thereby steered. The friction coefficient of the tires 6 at this time is extremely large when the vehicle speed is low. In particular, the coefficient of friction is large when turning the vehicle (an operation to turn the vehicle while the vehicle is stationary), such as when parking in a garage or parallel parking.
The electric motor 7 assists this force, which is controlled by the control device 8 based on the output obtained from the torque sensor 2.
The voltage from the battery 9 is applied to the motor 7 to control its current value. This current value also changes depending on the vehicle speed and steering angle sensor. The speed reducer 10 amplifies the assist force of the electric motor 7. FIG. 2 shows a block diagram of the above control. Rudder angle sensor 18 (11)
detects the deviation angle of the tire from its straight position.

The output of the torque sensor 2 is input to a function generator 12. This function generator 12 has characteristics as shown in FIG. That is, the function generator determines a command current (assist force) for the output (steering force) of the torque sensor. Further, the command current is corrected based on the vehicle speed. That is, at high speeds, the steering force is increased to provide the characteristics shown by the dotted line in FIG. 3 in order to obtain stable operability.

On the other hand, the output of the torque sensor is input to a differentiating circuit 13, and the output is added to the output of the function generator 12. This is the amount of current added to remove the inertia of the motor. This added value is corrected by the output of the steering angle sensor so that the vehicle returns to the straight direction. This correction is independent of the steering force, and even if there is no steering force, if the tires are deviated from the straight-ahead position, current is applied to the electric motor 7 to return them to the straight-ahead position.

This calculation is performed by the steering angle correction circuit 14. That is, the sign of the accelerated or decelerated value is determined, and if it is positive, the current direction is switched so that the rotation is clockwise (or counterclockwise).

Such a steering correction command is issued by the conduction rate setting circuit 1.
9 to the electric motor 7, and the electric motor 7 applies the rotational force to the tires 6 through the reducer 10 to drive the tires 6.

FIG. 4 shows the structure of a means for setting the neutral points of the torque sensor 2 and the steering angle sensor 18 (11) using the control described above, and FIG. 5 shows a control block diagram thereof.

FIG. 6 is an example of the output of the torque sensor.

That is, when the steering wheel is operated to the right, right-hand torque is applied to the torque sensor, and the output is proportional to the torque, exhibiting characteristics like A-B in the figure. In addition, when the handle is operated to the left, the outputs A-C in the figure are shown. The same applies to the steering angle sensor.

FIG. 7 is an example of a torque neutral adjustment circuit,
The output voltage can be varied by connecting a variable resistor between the stabilizer voltage V _CC and earth GND and moving the variable terminal. The same applies to the steering angle neutral circuit, which may be a digital switch instead of a variable resistor.

In FIG. 4, the torque sensor output signal, torque neutral adjustment signal, steering angle sensor output signal, and steering angle neutral adjustment signal are transmitted to the CPU via the I/O of the control device.
connected to.

If the indicators (e.g. lamps) indicating that the torque and steering angle are neutral are L _T and L _D , these are also CPU
It is connected via I/O.

If the sensor output when the torque is neutral is V _T (V), and the sensor output when the steering angle is neutral is V _D (V), each neutral signal
All you have to do is adjust the variable resistors so that V _CT and V _CD become V _CC = V _CT and V _D = V _DT , but instead of using a voltmeter, use neutral point indicators L _T and L _D. Depending on the situation,
Easy to adjust.

Next, an example of the adjustment method will be described.

First, the vehicle is in a straight-ahead state, with zero steering force applied to the steering wheel. At this time, the control flow shown in FIG. 5 is turned on. The CPU reads the torque sensor output and the torque neutral adjustment signal, determines whether they are the same, and if they are not the same, the neutral indicator L _T
Does not turn on. Therefore, adjust the variable resistor so that the indicator turns on. The control device detects that the sensor output at this time is at the neutral point and can store it. The same applies to the steering angle neutral adjustment. The storage means can be such that the adjustable variable resistor is installed inside and outside the control device, stored as part of the hardware, or stored by other methods (such as RAM), and the adjustable variable resistor can be removed.

According to this embodiment, it is possible to easily adjust the sensor output voltage V _T during torque neutral and the steering angle neutral voltage V _D due to differences in performance of each vehicle without the need for special measuring instruments. Moreover, the adjustment circuit can be made at low cost.

〔Effect of the invention〕

As described above, according to the present invention, an electric power steering control device having a torque and steering angle sensor neutral adjustment function that can perform neutral adjustment of each sensor in a short time can be easily provided.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the system configuration of the present invention, and FIG. 2 is a block diagram of the present control device.
FIG. 3 is a torque sensor and command current characteristic diagram of this control device, FIG. 4 is a block diagram showing the system configuration, and FIG. 5 is a flowchart of this control device.
Figure 6 is a torque sensor output characteristic diagram, Figure 7 is:
FIG. 3 is a torque neutral adjustment circuit diagram. 1...Handle, 2...Torque sensor, 3...
Shaft, 4...Rack, 5...Pinion, 6...
...Tire, 7...Electric motor, 8...Control device, 9...
... Battery, 10 ... Decelerator, 11 ... Rudder angle sensor, 12 ... Function generator, 13 ... Differential circuit, 1
4... Rudder angle correction circuit, 17... Vehicle speed detection circuit, 1
8... Rudder angle detection circuit, 19... Duty ratio setting circuit.

Claims (1)

[Claims] 1. A torque sensor that detects the steering force of a steering wheel, a torque neutral adjustment circuit for the torque sensor, a steering angle sensor that detects the position of a tire, and a steering angle neutral adjustment circuit for the steering angle sensor. , comprising an indicator that displays each of the neutral points, an electric motor that generates rotational force to assist the steering force of the steering wheel, and a control device that applies voltage to the electric motor from a battery and controls the flowing current. In the electric power steering control device, the output signal of the torque sensor, the torque adjustment signal, the output signal of the steering angle sensor, and the adjustment signal during the steering angle are taken in and the mechanical neutral point of the vehicle is electrically determined. a control means for converting and determining the neutral point; a means for calculating and storing the magnitude of the electrical signals of the respective torque sensors and the steering angle sensor; An electric power steering control device comprising: a display means for displaying when the angle adjustment signal and the angle adjustment signal are respectively neutral.