JPH06122376A - Power steering controller - Google Patents

Abstract

PURPOSE:To obtain a power steering controller which secures the stability in steering by changing the assistance characteristic and always secure the safety of a vehicle, when a wheel tends to be locked by the application of the sharp brake in the sharp deceleration of a vehicle or on a slippy road sur face such as on a snow road. CONSTITUTION:A power steering controller is equipped with a microcomputer 4A which determines the driving torque of a dc motor 9 on the basis of the steering torque information and the car speed information during the steering of a steering wheel and generates a driving signal for the dc motor 9 on the basis of the driving torque and outputs the driving signal, and further equipped with a microcomputer 30 which generates the brake operation signal for a wheel on the basis of the wheel speed information and the brake detection information and outputs the brake operation signal, and the dc motor 9 is drive- controlled by changing the assistance characteristic in outputting the brake operation signal supplied from the microcomputer 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering control device for assisting (assisting) the turning force of a steering wheel based on steering torque information and vehicle speed information, and more particularly, a so-called anti-skid brake system for controlling braking force based on wheel speed information. The present invention relates to a power steering control device that effectively uses information from a device (hereinafter referred to as ABS).

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional power steering control device. In the figure, 1 is a torque sensor that detects a steering torque (steering angle) of a steering wheel (not shown), 2a and 2b are vehicle speed sensors that detect the ground speed of the vehicle, 3 is a torque sensor 1, and vehicle speed sensors 2a and 2b. An interface 4 to which a detection output such as the above is supplied, 4 is a main microcomputer that calculates a steering assist force or the like according to the steering direction and the vehicle speed based on the steering torque information and the ground speed information of the vehicle that are input via the interface 3, Reference numeral 5 is a sub-microcomputer that performs the same calculation based on the same input information as the main microcomputer 4.

A fail safe relay 6 is connected to the main microcomputer 4 and the sub microcomputer 5 and is energized by these outputs to supply the power from the battery 7 to a motor drive circuit, a clutch drive circuit, etc., which will be described later. Is connected to the main microcomputer 4 and the sub-microcomputer 5, and a motor drive circuit 10 for outputting a drive signal to the DC motor 9 for the steering assist actuator based on the outputs of these is connected to the main microcomputer 4, The clutch drive circuit outputs a drive signal to the clutch 11 based on the output.

Thus, the power steering control device of FIG. 4 has two microcomputers and outputs a control signal when the conditions for driving the DC motors for the steering assist force actuators of both outputs match. In other words, a so-called fail-safe configuration in which the control signals are output only when both microcomputers show the same calculation result is provided to ensure vehicle safety.

[0005]

Since the conventional power steering control device is constructed as described above, the wheels are likely to be locked by sudden braking when the vehicle decelerates suddenly or on a slippery road surface such as a snowy road. If the steering force of the steering wheel is reduced due to the operation of the power steering control device, the steering wheel may fluctuate and the steering stability may not be obtained, and the safety of the vehicle may not be ensured. It was

The present invention has been made in order to solve such a problem. For example, when the vehicle is suddenly decelerating or when the wheels are about to lock due to sudden braking on a slippery road surface such as a snowy road. Aims to obtain a power steering control device that changes the assist characteristics to stabilize the steering and always ensure the safety of the vehicle.

[0007]

A power steering control device according to a first aspect of the present invention determines a drive torque of a steering assisting motor on the basis of steering torque information and vehicle speed information when steering a steering wheel, First control means for forming and outputting a drive signal for the steering assisting motor based on the drive torque, and second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information. A control means is provided to drive and control the motor by changing the assist characteristic at the time of outputting the brake actuation signal from the second control means.

A power steering control device according to a second aspect of the present invention determines a driving direction and a driving torque of a steering assisting motor based on steering torque information and vehicle speed information at the time of steering a steering wheel. First control means for forming and outputting a drive signal for the steering assisting motor based on the drive torque, and second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information. Control means and road surface friction coefficient estimating means for estimating a road surface friction coefficient based on the wheel speed information are provided, and are estimated by the road surface friction coefficient estimating means when a brake operation signal is output from the second control means. The assist characteristic is changed according to the estimated value of the friction coefficient of the road surface to drive and control the motor.

A power steering control device according to a third aspect of the present invention determines a driving direction and a driving torque of a steering assisting motor based on steering torque information and vehicle speed information at the time of steering a steering wheel, and determines the driving direction and the driving torque. First control means for forming and outputting a drive signal for the steering assisting motor based on the drive torque, and second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information. A control means is provided to drive and control the motor by changing the assist characteristic at the time of outputting the brake actuation signal from the second control means.

According to another aspect of the power steering control device of the present invention, the drive direction and drive torque of the steering assist motor are determined based on the steering torque information and the vehicle speed information when the steering wheel is steered. First control means for forming and outputting a drive signal for the steering assisting motor based on the drive torque, and second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information. Control means and road surface friction coefficient estimating means for estimating a road surface friction coefficient based on the wheel speed information are provided, and are estimated by the road surface friction coefficient estimating means when a brake operation signal is output from the second control means. The assist characteristic is changed according to the estimated value of the friction coefficient of the road surface to drive and control the motor.

[0011]

According to the present invention, the drive torque of the steering assisting motor is determined by the first control means based on the steering torque information and the vehicle speed information when the steering wheel is steered.
A drive signal for the steering assist motor is formed based on the drive torque, a brake operation signal for the wheel is formed by the second control means based on the wheel speed information and the brake detection information, and the brake operation signal is output. When the ABS device is operating, the assist characteristic of the power steering control device is changed to drive and control the steering assist motor. As a result, even when the wheels are about to be locked, the stability of the operation can be achieved and the safety of the vehicle can be always ensured.

According to another aspect of the present invention, the drive torque of the steering assisting motor is determined by the first control means based on the steering torque information and the vehicle speed information during steering of the steering wheel, and based on this drive torque. A drive signal for the steering assisting motor is formed, a brake control signal for the wheel is formed by the second control means based on the wheel speed information and the brake detection information, and a road surface friction coefficient estimating means forms the road surface based on the wheel speed information. When the friction coefficient is estimated and the brake operation signal is output, that is, when the ABS device is operating, the assist characteristic of the power steering control device is set according to the estimated value of the estimated friction coefficient of the road surface. The steering assist motor is drive-controlled after being changed. As a result, even if the wheels are about to lock
The vehicle safety can always be ensured with a higher accuracy.

According to another aspect of the present invention, the first control means determines the drive direction and drive torque of the steering assist motor based on the steering torque information and the vehicle speed information when the steering wheel is steered. And a drive signal for the steering assisting motor on the basis of the drive torque, and a brake operating signal for the wheel is formed on the basis of the wheel speed information and the brake detection information by the second control means, and the brake operating signal is output. When the ABS device is operating, the assist characteristic of the power steering control device is changed to drive and control the steering assist motor. As a result, even when the wheels are about to be locked, the stability of the operation can be achieved and the safety of the vehicle can be always ensured.

According to a fourth aspect of the present invention, the first control means determines the drive direction and drive torque of the steering assisting motor based on the steering torque information and the vehicle speed information when the steering wheel is steered. And a drive signal for the steering assisting motor based on the drive torque, a second control means for forming a brake operation signal for the wheel based on the wheel speed information and the brake detection information, and a road surface friction coefficient estimating means for forming the wheel speed. The friction coefficient of the road surface is estimated based on the signal, and when the brake operation signal is output, that is, when the ABS device is operating, the power steering according to the estimated value of the estimated friction coefficient of the road surface. The steering assist motor is driven and controlled by changing the assist characteristic of the control device. As a result, even when the wheels are about to lock, the stability of the operation can be achieved, and the safety of the vehicle can be always ensured with a higher accuracy.

[0015]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.
Portions corresponding to those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted. In the figure, 4A is a microcomputer as a first control means for power steering control, and this microcomputer 4A is based on steering torque information which is an output of the torque sensor 1 inputted through the interface 3. The drive direction of the DC motor 9 is determined, the drive torque of the DC motor 9 is determined based on the steering torque information and a pseudo vehicle body speed signal from an ABS microcomputer described later, and based on these drive directions and drive torques. The basic operation is to generate and output a direction signal and a torque signal to the DC motor 9, especially when the vehicle is suddenly decelerating or when the wheels are about to be locked by sudden braking on a slippery road surface such as a snowy road. That is, when the ABS device is operating, the assist characteristic (drive It serves to change the torque characteristic and the driving direction characteristic).

Reference numeral 21 denotes a front left wheel wheel speed sensor, 22 a front right wheel wheel speed sensor, 23 a rear left wheel wheel speed sensor, and 24.
Is a rear right wheel speed sensor, 25 is a G sensor for detecting acceleration / deceleration of the vehicle body, and 26 is a stop lamp switch. Reference numeral 30 generates a pseudo vehicle body speed signal of the vehicle body based on the outputs of the wheel speed sensors 21 to 24 and the G sensor 25, and also outputs a brake operation signal of the wheel on the basis of the pseudo vehicle body speed signal and the output of the stop lamp switch 26. It is a microcomputer as a second control means for controlling the generated anti-skid brake.

The microcomputer 30 estimates a vehicle body speed based on the outputs of the wheel speed sensors 21 to 24 and the G sensor 25, and forms a pseudo vehicle body speed signal from the estimation result. , A wheel speed selection circuit 32 that selects the one with a lower rotation speed of the wheel based on the outputs of the wheel speed sensors 23 and 24, and a vehicle body speed estimation circuit 3
1 and A based on the output of the stop lamp switch 26
And a control end determination circuit 33 for determining the end of the control operation of the BS device.

The microcomputer 30 also includes a slip ratio / deceleration calculating circuit 34 for calculating a slip ratio / deceleration based on the outputs of the wheel speed sensor 21 and the vehicle speed estimating circuit 31, the wheel speed sensor 22, and the vehicle speed. Estimation circuit 3
The slip ratio / deceleration calculation circuit 35 for calculating the slip ratio / deceleration based on the output of 1 and the slip ratio / deceleration based on the outputs of the wheel speed selection circuit 32 and the vehicle body speed estimation circuit 31.
And a slip ratio / deceleration calculation circuit 36 for calculating deceleration.

Further, the microcomputer 30 includes a slip ratio / deceleration calculation circuit 34 and a control end determination circuit 33.
The front left wheel control circuit 37 that forms a control signal (brake actuation signal) for the front left wheel by determining the locked state of the wheel, that is, how much the front left wheel is locked based on the output of the slip ratio / deceleration. Before forming the control signal (brake actuation signal) for the front right wheel by determining the locked state of the wheel, that is, how much the front right wheel is locked, based on the outputs of the calculation circuit 35 and the control end determination circuit 33. Right wheel control circuit 38 and slip ratio / deceleration calculation circuit 36
And a control signal (brake actuation signal) for the rear wheel is determined by determining the locked state of the wheel, that is, which of the rear wheels is locked, based on the output of the control end determination circuit 33. And a wheel control circuit 39.

The pseudo vehicle body speed signal from the vehicle body speed estimating circuit 31 of the microcomputer 30 is also supplied to the microcomputer 4A for controlling the power steering as vehicle speed information. Therefore, the microcomputer 30 not only functions as an original anti-skid brake control but also substantially functions as a partial power steering control.

Reference numeral 41 denotes a front left wheel solenoid valve for controlling the opening of the front left wheel control circuit 37 by a control signal from the front left wheel control circuit 37 to adjust the hydraulic pressure of a brake (not shown), and 42 denotes a front right wheel control circuit 38. Is controlled by the control signal from the rear wheel control circuit 39 to control the opening of the front right wheel solenoid valve 43 for adjusting the hydraulic pressure of the brake. This is a solenoid valve for the rear wheel for

Reference numeral 44 is a road surface friction coefficient estimating circuit for estimating the friction coefficient μ of various road surfaces based on the output of the vehicle body speed estimating circuit 31, and 45 is a control circuit 37 of the microcomputer 30.
It is a brake actuation determination circuit that determines whether a brake actuation signal as a control signal is output from ~ 39, that is, whether the ABS device is actuated. The road surface friction coefficient μ in the road surface friction coefficient estimation circuit 44 is
Usually, the range is 0 to 1, where 0 represents a so-called slippery and slippery road surface where the vehicle does not stop even when the brake is applied, and 1 represents a so-called non-slip road surface where the vehicle suddenly stops when the brake is applied. Represent

The outputs of the road surface friction coefficient estimating circuit 44 and the brake operation determining circuit 45 are supplied to the power steering control microcomputer 4A. The functions of the road surface friction coefficient estimating circuit 44 and the brake operation determining circuit 45 may be performed by the microcomputer 4A.

Although a fail-safe relay for the ABS device is not shown in FIG. 1, it may be provided exclusively for the ABS device, or a fail-safe relay 6 (not shown) may be provided in the microcomputer 4A and the microcomputer. Relay and AB for power steering control device connected to 30 respectively
A fail-safe relay including a relay for S device may be a fail-safe relay, or a fail-safe relay (not shown) may be a fail-safe relay commonly used for a power steering control device and an ABS device, and an energizing signal from both microcomputers may be used. The fail safe relay 6 may be energized when they match.

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described. First, the microcomputer 4
A confirms the operation of the power steering control device based on the output of each sensor at the time of starting the operation of the vehicle, and if normal, outputs a fail safe relay energizing signal for operating the power steering control device. The safe relay 6 is energized so that the power from the battery 7 is supplied to the motor drive circuit 8, the clutch drive circuit 10, and the like.

Similarly, the microcomputer 30 confirms the operation of the ABS device based on the output of each sensor at the time of starting the operation of the vehicle, and if normal, outputs a fail safe relay energizing signal for operating the ABS device. It outputs and energizes a fail-safe relay (not shown), so that the power from the battery 7 is supplied to a valve drive circuit (not shown) and solenoid valves 41 to 43 provided in front of the solenoid valves 41 to 43. It is supplied to a hydraulic unit (not shown) including the like.

Then, the microcomputer 4A supplies a clutch current command signal to the clutch drive circuit 10,
Thus, the clutch drive circuit 10 supplies, for example, a PWM-modulated drive signal to the clutch 11 to operate it. Further, although not shown, the clutch current is fed back from the clutch 11 to the clutch drive circuit 10 for detecting an abnormality.

Now, in the case of normal operation in which it is not necessary to apply a sudden brake to the vehicle to suddenly decelerate, that is, to operate the ABS device, the microcomputer 4A uses the torque sensor through the interface 3 to operate. The steering torque information at the time of steering the steering wheel is fetched from No. 1, and the pseudo vehicle body speed signal from the vehicle body speed estimation circuit 31 of the microcomputer 30 corresponding to the output values of the wheel speed sensors 21 to 24 is fetched as the vehicle speed information to obtain the steering torque. The drive direction of the DC motor 9 is determined based on the information, and the drive torque of the DC motor 9 is determined based on the steering torque information and the vehicle speed information.

Then, the microcomputer 4A further refers to a reference control map stored in advance in a memory (not shown) on the basis of the driving direction and the driving torque, and the friction coefficient μ at this time, that is, the road surface, is determined. The corresponding drive direction and drive torque when 1 is read as a reference value, the assist amount for the DC motor 9 is determined from this, and a direction signal and a torque signal corresponding to this assist amount are generated and output.

In the case of normal driving, the pseudo vehicle body speed signal output from the vehicle body speed estimating circuit 31 is substantially the value detected by the wheel speed sensors 21 to 24, which is substantially used as vehicle speed information. Then, the motor drive circuit 8 forms a drive signal based on the direction signal and the torque signal from the microcomputer 4A, and outputs the drive signal to the DC motor 9
To drive this.

On the other hand, for example, when the vehicle suddenly decelerates or when the wheels are about to lock due to sudden braking on a slippery road surface such as a snowy road, that is, when the ABS device is operating, the microcomputer 4A causes the interface 3 to operate. The steering torque information at the time of steering the steering wheel is fetched from the torque sensor 1 via the, and the output values of the wheel speed sensors 21 to 24 immediately before the wheels are locked are output to the G sensor 25 in the vehicle body speed estimation circuit 31 of the microcomputer 30. Based on the steering torque information, the driving direction of the DC motor 9 is determined by taking in the pseudo vehicle speed signal estimated and output based on the steering torque information, and the driving torque of the DC motor 9 is determined based on the steering torque information and the vehicle speed information. To decide.

Then, the microcomputer 4A further multiplies the reference value of the above-mentioned reference control map by the estimated value of the friction coefficient μ from the road surface friction coefficient estimation circuit 44 at this time based on the drive direction and the drive torque. The assist characteristic is corrected, the assist amount for the DC motor 9 is determined from this, and a direction signal and a torque signal corresponding to the assist amount are generated and output.

The motor drive circuit 8 forms a drive signal based on the direction signal and the torque signal from the microcomputer 4A, and supplies this drive signal to the DC motor 9 to drive it.

FIG. 2 shows the relationship between the driving torque and the motor current supplied to the DC motor 9 when the friction coefficient μ of the road surface is used as a parameter. The relation between the motor current when the friction coefficient μ of the road surface is 1 is shown. When the driving torque characteristic is based on the change in driving torque, the smaller the friction coefficient μ, that is, the more slippery the road surface, the smaller the inclination of the characteristic, and conversely, the larger the friction coefficient μ, the less slippery the road surface. , The slope of the characteristic becomes large.

Therefore, the microcomputer 4A sets the friction coefficient μ of the road surface from the road surface friction coefficient estimation circuit 44 at that time to the reference value of the reference control map according to various road surface conditions.
When the road surface is slippery, the slope of the characteristic is reduced to reduce the assist amount, and when the road surface is difficult to slip, the slope of the characteristic is increased to increase the assist amount. The driving torque characteristic as is corrected.

Further, the routine for determining the assist amount in the microcomputer 4A will be described with reference to FIG. First, in step S1, the driving direction and the driving torque are determined based on the steering torque information and the pseudo vehicle body speed signal as the vehicle speed information fetched from the torque sensor 1 and the microcomputer 30, respectively.
In step 2, it is determined whether the ABS device is operating based on the output from the brake operation determining circuit 45.

If the ABS device is not in operation,
That is, in the case of normal driving that does not require sudden braking of the vehicle and sudden deceleration, the basic control map stored in advance in the memory is referred to in step S3, and in step S4, the That is, the corresponding driving direction and driving torque when the friction coefficient μ of the road surface is 1 are read as a reference value, the assist amount for the DC motor 9 is determined from this, and the direction signal and the torque signal corresponding thereto are generated. Output.

On the other hand, in step S2, if the ABS device is operating, that is, when the vehicle is suddenly decelerating or the wheels are about to lock due to sudden braking on a slippery road surface such as a snowy road, In step S5, the road surface friction coefficient μ from the road surface friction coefficient estimation circuit 44 at this time
Is read, and the reference control map stored in the memory is referred to in step S6.
At, the assist characteristic is corrected by multiplying the reference value of the reference control map by the estimated value of the friction coefficient μ of the road surface read in step S5.

That is, in the case of correcting the driving torque characteristic as the assist characteristic, for example, when the driving torque characteristic based on the change in the driving torque with respect to the motor current when the friction coefficient μ of the road surface is 1, the reference value is Multiplying the estimated value of the friction coefficient μ of the road surface, the smaller the friction coefficient μ, that is, the more slippery the road surface, the smaller the inclination of the characteristics, and conversely, the larger the friction coefficient μ, that is, the less slippery the road surface, The slope of the assist characteristic is corrected so as to increase the slope of (see FIG. 2).

Then, in step S4, the assist amount for the DC motor 9 is determined based on the corrected assist characteristic, and the direction signal and the torque signal corresponding thereto are generated and output.

In this way, the microcomputer 4A
Is a power steering control device depending on various road surface conditions, for example, when the vehicle suddenly decelerates or when the wheels are about to lock due to sudden braking on a slippery road surface such as a snowy road, that is, when the ABS device is operating. The amount of assist is reduced and the steering handle is made hard to move, improving the stability of the steering.

The function of the ABS device of the microcomputer 30 is the same as that of a conventional one. That is, in the microcomputer 30, the vehicle body speed estimation circuit 3
1 takes in the outputs of the wheel speed sensors 21 to 24 and the G sensor 25 to form a pseudo vehicle body speed signal and supplies it to the slip ratio / deceleration calculation circuits 34 to 36. The outputs of the sensors 23 and 24 are taken in and the one with the lower rotational speed of the wheel is selected and supplied to the slip ratio / deceleration calculation circuit 36.

The slip ratio / deceleration calculation circuits 34 to 36 calculate the slip ratio and deceleration of the wheels based on the input information, and supply the calculated results to the corresponding control circuits 37 to 39, respectively.

The control end judging circuit 33 judges whether or not the control operation of the ABS device is completed based on the outputs of the vehicle body speed estimating circuit 31 and the stop lamp switch 26, and the control operation of the ABS device is completed. That is, when the pseudo vehicle body speed signal equivalent to the output values of the wheel speed sensors 21 to 24 is input from the vehicle body speed estimation circuit 31 and the output of the stop lamp switch 26 is, for example, "0" (the brake is not applied). At this time), the control operation end determination signal is output to the control circuits 37 to 39.

If the control operation of the ABS device is not completed, that is, the control end determination circuit 33 outputs the output of the G sensor 25 from the output values of the wheel speed sensors 21 to 24 immediately before the wheels are locked by the vehicle body speed estimation circuit 31. When the pseudo vehicle body speed signal estimated based on the above is input and the output of the stop lamp switch 26 is "1" (when the brake is applied), the control circuit 3 outputs the determination signal indicating that the control operation is not completed.
It outputs to 7-39.

Therefore, the control circuits 37 and 38 are controlled by the ABS.
When the control operation of the device is completed, the control signal turns off the solenoid valves 41 and 42 to increase the hydraulic pressure, and applies the braking force corresponding to the depression of the brake to the corresponding front left wheel and front right wheel, respectively. . Similarly, when the control operation of the ABS device is completed, the control circuit 39 turns off the solenoid valve 43 by the control signal to increase the oil pressure, and the rotation speed selected by the wheel speed selection circuit 32 is controlled. Braking force is applied to the lower rear wheels according to the depression of the brake.

On the other hand, when the control operation of the ABS device is not completed, the control circuits 37 and 38 turn on the solenoid valves 41 and 42 by the control signal to reduce the hydraulic pressure, that is, to loosen the hydraulic pressure to an appropriate hydraulic pressure. Braking force is applied to the corresponding front left wheel and front right wheel so as not to lock. Similarly, when the control operation of the ABS device is not completed, the control circuit 39 turns on the solenoid valve 43 by the control signal to reduce the oil pressure, that is, to loosen the oil pressure to an appropriate oil pressure, and the wheel speed selection circuit 32 operates. Braking force is applied to the rear wheel side of the selected low rotational speed so as not to lock.

As described above, in this embodiment, for example, when the vehicle is suddenly decelerating or when the wheels are about to be locked due to sudden braking on a slippery road surface such as a snowy road, that is, when the ABS device is operating, The assist value is corrected by multiplying the reference value of the reference control map during normal operation by the estimated value of the friction coefficient μ from the road surface friction coefficient estimation circuit 44 according to the road surface condition at that time, and the assist amount of the power steering control device is calculated. By reducing the amount, it is possible to secure the safety of the vehicle by making the steering wheel hard to move and improving the steering stability.

Example 2. In the above embodiment, the assist characteristic including the drive torque characteristic and the drive direction characteristic is changed according to the friction coefficient μ of the road surface at the time of operation of the ABS device, that is, when the brake operation signal is output. Although the case has been described, if the brake actuation signal is output, the assist characteristic including the drive torque characteristic and the drive direction characteristic may be corrected regardless of the friction coefficient μ of the road surface.

Example 3. Further, in the above-described embodiment, the case where both the driving torque characteristic and the driving direction characteristic are included as the assist characteristic to be corrected has been described, but the assist characteristic may include only the driving torque characteristic.

Example 4. Further, in the above embodiment, in order to form the drive signal for driving the DC motor 9, the drive direction and drive torque of the DC motor 9 are determined based on the vehicle speed information and the steering information, and the drive signal for the DC motor 9 is thereby determined. However, it is also possible to use only the drive torque of the DC motor 9 to form the drive signal for the DC motor 9.

Example 5. Further, in the above embodiment, the assist characteristic is corrected by multiplying the reference value of the reference control map by the friction coefficient μ of the road surface at that time, but the present invention is not limited to this, and for example, the reference control map Alternatively, a plurality of control maps corresponding to the friction coefficient μ of various road surfaces may be stored in advance in a memory, and the required assist characteristics may be selected by referring to the corresponding control map when necessary.

Example 6. Further, the configuration of the ABS device is not limited to the configuration of the above-described embodiment, and other configurations may be used, and the output of the vehicle speed sensor generally used for the power steering control device is used as the vehicle speed information without using the pseudo vehicle body speed signal. Good.

[0054]

As described above, according to the first aspect of the present invention, the drive torque of the steering assisting motor is determined based on the steering torque information and the vehicle speed information when the steering wheel is steered.
First control means for forming and outputting a drive signal for the steering assist motor based on the drive torque, and second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information. The control means is provided to control the drive of the motor by changing the assist characteristic at the time of outputting the brake operation signal from the second control means. When the wheels are about to lock due to sudden braking on an easy road surface, the assist amount of the power steering control device is reduced according to the braking force, and the steering wheel is made difficult to move to ensure stable steering. This has the effect of ensuring vehicle safety.

According to the second aspect of the invention, the drive direction and drive torque of the steering assisting motor are determined based on the steering torque information and the vehicle speed information when steering the steering wheel, and the drive direction and drive torque are determined. A first control means for forming and outputting a drive signal for the steering assisting motor based on the above, and a second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information.
Control means and a road surface friction coefficient estimating means for estimating a road surface friction coefficient based on the wheel speed information, and the road surface friction coefficient estimating means estimates the brake operation signal when the second control means outputs. Since the assist characteristics are changed according to the estimated value of the friction coefficient of the road surface to drive and control the motor, for example, when the vehicle suddenly decelerates or on a slippery road surface such as a snowy road, the wheel is suddenly braked. If the vehicle is about to lock, the assist amount of the power steering control device is reduced according to the braking force and the road surface condition, the steering handle is made hard to move, and the steering stability is improved. This has the effect of ensuring the safety of the vehicle at all times.

According to the third aspect of the invention, the driving direction and driving torque of the steering assisting motor are determined based on the steering torque information and the vehicle speed information at the time of steering the steering wheel, and the driving direction and driving torque are determined. A first control means for forming and outputting a drive signal for the steering assisting motor based on the above, and a second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information.
The control means is provided to control the drive of the motor by changing the assist characteristic at the time of outputting the brake operation signal from the second control means. When the wheels are about to lock due to sudden braking on an easy road surface, the assist amount of the power steering control device is reduced according to the braking force, and the steering wheel is made difficult to move to ensure stable steering. This has the effect of ensuring vehicle safety.

According to the fourth aspect of the invention, the driving direction and driving torque of the steering assisting motor are determined based on the steering torque information and the vehicle speed information at the time of steering the steering wheel, and the driving direction and driving torque are determined. A first control means for forming and outputting a drive signal for the steering assisting motor based on the above, and a second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information.
Control means and a road surface friction coefficient estimating means for estimating a road surface friction coefficient based on the wheel speed information, and the road surface friction coefficient estimating means estimates the brake operation signal when the second control means outputs. The assist characteristic is changed according to the estimated value of the friction coefficient of the road surface to drive and control the motor.For example, when the vehicle is suddenly decelerating or on a slippery road surface such as a snowy road, the wheel is locked by sudden braking. If so, the assist amount of the power steering control device is reduced according to the braking force and the road surface condition, the steering handle is made hard to move, and the steering stability is improved, and there is a more accurate probability that the vehicle will always operate. The effect is that the safety of can be secured.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a power steering control device according to the present invention.

FIG. 2 is a characteristic diagram for explaining the operation of one embodiment of the present invention.

FIG. 3 is a flowchart for explaining the operation of the embodiment of the present invention.

FIG. 4 is a configuration diagram showing a conventional power steering control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Torque sensor 4A, 30 Microcomputer 8 Motor drive circuit 9 DC motor 21-24 Wheel speed sensor 25 G sensor 26 Stop lamp switch 44 Road surface friction coefficient estimation circuit 45 Brake operation determination circuit

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Claims (4)

[Claims] 1. A drive torque of a steering assist motor is determined based on steering torque information and vehicle speed information when steering a steering wheel, and a drive signal for the steering assist motor is formed and output based on the drive torque. And a second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information. The brake actuation signal from the second control means is provided. A power steering control device characterized in that the output assist characteristic is changed to drive and control the motor. 2. A drive torque of a steering assist motor is determined based on steering torque information and vehicle speed information when steering a steering wheel, and a drive signal for the steering assist motor is formed and output based on the drive torque. And a second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information, and estimating the friction coefficient of the road surface based on the wheel speed information. A road surface friction coefficient estimating means, the assist characteristic is changed according to the estimated value of the road surface friction coefficient estimated by the road surface friction coefficient estimating means when the brake operation signal is output from the second control means. A power steering control device characterized in that a motor is drive-controlled. 3. A driving direction and a driving torque of a steering assist motor are determined based on steering torque information and vehicle speed information when steering a steering wheel, and the steering assist motor is driven based on the driving direction and the driving torque. The second control means includes first control means for forming and outputting a signal, and second control means for forming and outputting a brake actuation signal for the wheel based on the wheel speed information and the brake detection information. A power steering control device characterized in that the assist characteristic at the time of outputting a brake operation signal from the motor is changed to drive and control the motor. 4. A driving direction and a driving torque of a steering assisting motor are determined based on steering torque information and vehicle speed information when steering a steering wheel, and the steering assisting motor is driven based on the driving direction and the driving torque. First control means for forming and outputting a signal, second control means for forming and outputting a brake actuation signal for a wheel based on wheel speed information and brake detection information, and road surface based on the wheel speed information And a road surface friction coefficient estimating means for estimating the friction coefficient of the road surface, and assisting in accordance with the estimated value of the friction coefficient of the road surface estimated by the road surface friction coefficient estimating means when the brake operation signal is output from the second control means. A power steering control device characterized in that characteristics are changed to drive and control the motor.