JPH0624350A - Motor driven power steering device - Google Patents

Abstract

PURPOSE:To improve steering performance by effecting correction according to a steering state through fuzzy inference. CONSTITUTION:Fuzzy inference is performed by means of steering torque, a car speed, a steering angular velocity, and a steering angular acceleration, all serving as an input parameter according to a given fuzzy rule, and an inertia compensation gain Ka and a viscous compensation gain Kv are computed. An inertia compensation value and a viscous compensation value are respectively corrected by means of an inertia compensation gain and a viscous compensation gain. Thus, a gain is corrected through fuzzy inference according to a steering state and steering performance is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering device suitable for use in a vehicle, and more particularly to a power steering device for assisting steering force by the rotational output of a motor.

[0002]

2. Description of the Related Art In recent years, electric power steering systems using a motor instead of a hydraulic type have been used as a vehicle power steering device, and the motor has an increasing tendency in the future due to advantages such as small size and light weight as an actuator.

In the conventional power steering system, the torque sensor detects the steering torque of the steering system, the vehicle speed sensor detects the vehicle speed, and the drive of the motor connected to the steering system is controlled based on the detection results. , Power assist is done. Generally, it is a vehicle speed sensitive type, and the assist force is controlled according to the torque sensor input so that it is light in the low speed range and heavy in the high speed range.

FIG. 5 is a block diagram showing an example of a steering mechanical system to which a conventional power steering device is applied. In this figure, the rotational force of the steering wheel 1 is transmitted to the steering gear 2 including a pinion gear via the handle shaft, is transmitted to the rack shaft 3 by the pinion gear, and the wheels 4 are turned through the knuckle arm and the like. To be done.

The rotational force of the steering assist (auxiliary) motor (DC motor) 6 controlled and controlled by the control device 5 is transmitted to the rack shaft 3 by the meshing of the steering gear 7 including a pinion gear and the rack shaft 3. This assists steering by the steering wheel 1. The rotating shafts of the handle 1 and the motor 6 are mechanically connected by gears 2 and 7 and a rack shaft 3.

On the other hand, a steering torque sensor 21 (see FIG.
Steering torque (return torque) is detected by
The vehicle speed is detected by the vehicle speed sensor 22 (see FIG. 6). Then, the motor 6 is controlled by the control device 5 based on the detected torque, the vehicle speed, and the like. The control device 5 and the motor 6 have a battery 8 mounted on the vehicle.
Is supplied with its operating power.

The control device 5 includes detectors such as a current detector and a voltage detector, a drive circuit for driving the motor 6, a computer (CPU, for example, microprocessor) that controls the motor 6 as a whole, a memory, and a computer. It is composed of an interface circuit with the input / output device.

Next, FIG. 6 is a block diagram showing various functions of a computer incorporated in the control device 5 in a different manner.
It is drawn together with blocks showing output devices and various circuits. In this figure, the assist command unit 20 includes a detection torque V of a torque sensor (steering torque detection means) 21.
_T and the vehicle speed V _S detected by the vehicle speed sensor (vehicle speed detecting means) 22 are given. The assist torque value instruction function unit 23 in the assist command unit 20 outputs a command value representing the assist torque to be generated by the motor 6 according to the detected torque V _T.

Further, the multiplication constant function unit 24 detects the detected vehicle speed V _S
A constant is generated according to the above, and this constant is multiplied by the above-mentioned assist torque command value in the multiplication calculator 25. As a result, the assist torque value (or motor current command value) output from the multiplication calculator 25 becomes a value determined by the detected torque V _T and the detected vehicle speed V _S , as shown in FIG. 7.

[0010] Figure 7 according to the steering torque V _T, which substantially proportional to the motor current (assist torque is generated) flows against the steering torque V _T of a range, when it exceeds the above range, as constant motor current flows (the assist torque is generated), also according to the vehicle speed V _S, the motor current (assist when when the vehicle speed V _S is high to reduce the motor current (assist torque), the vehicle speed V _S is low It indicates that an assist command for controlling the motor 6 is generated so as to increase the torque.

The detected torque V _T is also given to the phase compensator 26, and the differential value of the detected torque V _T is added to the output of the multiplication calculator 25 by the phase compensator 26.
The output (reference current command value) of the assist command unit 20 is supplied to the current control unit 60.

The reference current command value is added (or subtracted) with a command value for angular position, velocity and acceleration control (which may be at least one), which will be described later, and then as a target current command value, the current control unit 60. Given to. Current control unit 6
All of 0s may be configured by hardware circuits, or part of them may be realized by computer software.

The current control unit 60 is a PWM (Pulse) that follows the H-bridge drive method including, for example, four switching elements.
The motor 6 is driven and controlled by a chopper operation using a (Width Modulation) pulse, and current feedback control is performed. That is, the armature current detection unit 66 detects the armature current ia of the motor 6, and the target current command value and the detected current ia given by the current deviation calculation unit 61 are detected.
The deviation between and is calculated. The absolute value of this deviation is obtained by the absolute value converter 64, and the duty ratio of the PWM pulse is determined by the duty generator 65 based on this absolute value.

On the other hand, the polarity (positive or negative) of the deviation is discriminated by the positive / negative discriminating unit 62, the generated duty ratio and the discriminated polarity are given to the motor driving unit 63, and the motor driving unit 63 determines these values. Based on the above, the four switching elements wired in the H-bridge type are turned on / off to drive the motor 6.

The steering angular velocity dθ / dt (θ: represented by a theta dot in the drawing) is detected by the steering angular velocity detection / calculation means 35 and output to the viscosity compensation value instruction function section 31. The steering angular velocity dθ / dt corresponds to the steering amount. Further, the steering angular acceleration d ² θ / dt ² (in the drawing, θ:
(Indicated by theta-dot) is detected by the steering angular acceleration detection / calculation means 44 and output to the inertia compensation value instruction function unit 41. The steering angular acceleration d ² θ / dt ² corresponds to the steering acceleration.

In the following description, the steering angular velocity is represented as usual by using .theta. In the drawings and dots are added on the letters. However, since the dot display is difficult in the text of the specification, the steering angular velocity is represented by dθ / dt, steering angular acceleration is d ² θ /
It will be appropriately expressed as dt ² .

Therefore, the steering angular velocity dθ / dt is fed to the viscosity control unit 30 which performs negative feedback of the steering angular velocity and the like, and the steering angular acceleration d ² θ / dt ² is fed to the inertia control unit 4 which feeds positive feedback of the steering angular acceleration.
0, respectively, and the position of the motor 6,
Used for speed and acceleration control. Any one or two of these controls may be performed, or all of them may be performed.

The viscosity control unit (motor viscosity control means) 30 applies a viscous force to the movement of the steering angle and switches the magnitude of the viscous force according to the vehicle speed. The steering angular velocity dθ / dt is given to the viscosity compensation value instruction function unit 31, and this viscosity compensation value instruction function unit 31 outputs a command value that produces a larger absolute value and reverse torque as the velocity dθ / dt increases. .

On the other hand, the vehicle speed Vs detected by the vehicle speed sensor 22 is given to a vehicle speed calculation constant function section 34, and this function section 34 outputs a larger constant as the vehicle speed Vs is higher.
This vehicle speed calculation constant is calculated by the multiplication calculation unit 32 in the function unit 31.
The command value output from is multiplied.

This multiplication result is subtracted from the reference current command value output from the assist command unit 20 via the viscosity command output command unit 33. In this way, the output of the viscosity control unit 30 works to reduce the output of the assist command unit 20 to a greater extent as the steering angular velocity dθ / dt increases. Further, the larger the vehicle speed Vs is, the larger the constant becomes so that it is multiplied, and the effect of viscous braking becomes larger.

As a result, the instability when returning to the vehicle, which tends to become unstable as the vehicle speed increases, is suppressed, and a good steering feel is achieved. Further, at a low vehicle speed, the compensation that reduces the viscosity works, so that the viscous feeling of the steering wheel is reduced and a good steering wheel feeling is obtained.

The inertia control unit 40 controls the rotor inertia of the motor 6 as if the rotor inertia had decreased. The inertia control unit 40 eliminates the weight generated when the motor 6 does not follow the rotation of the steering wheel at the time of a sudden steering operation, or when the steering wheel is released. It acts to speed up the return speed. Steering angular acceleration d ²
θ / dt ² is given to the inertia compensation value instruction function unit 41, and this inertia compensation value instruction function unit 41 operates the steering angular acceleration d ² θ / d.
A value that compensates for the rotor inertia of the motor 6 is calculated according to t ² and output to the multiplication calculation unit 42.

On the other hand, the vehicle speed Vs detected by the vehicle speed sensor 22 is given to the vehicle speed calculation constant function section 43, and this vehicle speed calculation constant function section 43 outputs a larger constant as the vehicle speed Vs increases. This vehicle speed calculation constant is multiplied by the command value output from the inertia compensation value instruction function unit 41 in the multiplication calculation unit 42. Then, the multiplication result is the assist command unit 20.
Will be added to the reference current command value output from. The assist command section 20 and the current control section 60 constitute the control means 100.

Therefore, the viscosity control unit 30 applies negative feedback to the steering assist torque, and also changes the negative feedback gain of the motor angular velocity according to the vehicle speed. That is,
The negative feedback gain of the motor angular velocity is low at a low speed, and the negative feedback gain of the motor angular velocity is high at a high speed.

[0025]

However, in such a conventional electric power steering apparatus,
Since the acceleration positive feedback gain Ka of the inertia control unit 40 and the speed negative feedback gain Kv of the viscosity control unit 30 are constant, in order to improve the speed response, for example, an acceleration positive feedback gain (inertia compensation gain). If Ka is raised too high,
When the control system oscillates and the velocity negative feedback gain (viscosity compensation gain) Kv is increased too much in order to ensure stability (damping property), there is a problem that an unnecessary viscous feeling is generated during normal steering. . Therefore, there is a limit to improving the steering performance as it is.

Therefore, it is an object of the present invention to provide an electric power steering apparatus capable of improving steering performance by performing correction according to a steering state by fuzzy reasoning.

[0027]

In order to achieve the above object, an electric power steering apparatus according to a first aspect of the present invention is provided with an electric power steering apparatus, which is connected to a steering system and generates a steering assist torque, and a steering torque of the steering system. Steering torque detecting means for detecting the vehicle speed, vehicle speed detecting means for detecting the vehicle speed, steering angular velocity detecting means for detecting the steering angular velocity of the steering system, steering angular acceleration detecting means for detecting the steering angular acceleration of the steering system, An inertia control means for calculating an inertia compensation value for compensating the inertia of the motor based on the output of the steering angular acceleration detecting means, and a viscosity for calculating a viscosity compensation value for compensating the viscosity of the motor based on the output of the steering angular velocity detecting means. The assist command value for controlling the drive of the motor is calculated based on the outputs of the control means, the steering torque detection means and the vehicle speed detection means, and the assist command value is calculated. And a control means for correcting the command value with the inertia compensation value and the viscosity compensation value, in a predetermined fuzzy rule using the steering torque, the vehicle speed, the steering angular velocity, and the steering angular acceleration as input parameters. Fuzzy inference is performed according to, and fuzzy inference means for calculating the inertia compensation gain of the inertia control means and the viscosity compensation gain of the viscosity control means is provided, and the inertia control means determines the inertia compensation value based on the output of the fuzzy inference means. The viscosity control means corrects the viscosity compensation value based on the output of the fuzzy inference means.

The electric power steering apparatus according to the second aspect of the present invention is connected to a steering system and generates a steering assist torque, a steering torque detecting means for detecting a steering torque of the steering system, and a vehicle speed. Vehicle speed detection means,
Steering angular velocity detecting means for detecting the steering angular velocity of the steering system, steering angular acceleration detecting means for detecting the steering angular acceleration of the steering system, and inertia for compensating the inertia of the motor based on the output of the steering angular acceleration detecting means. Inertia control means for calculating a compensation value, viscosity control means for calculating a viscosity compensation value for compensating the viscosity of the motor based on the output of the steering angular velocity detection means, and based on the outputs of the steering torque detection means and the vehicle speed detection means In the electric power steering apparatus, the electric power steering apparatus includes: a control unit that calculates an assist command value for controlling the drive of the motor and corrects the assist command value by the inertia compensation value and the viscosity compensation value. , The steering angular velocity and the steering angular acceleration are input parameters, fuzzy inference is performed according to a predetermined fuzzy rule, and the Fuzzy inference means for calculating a correction value for correcting the strike command value provided, the control means, and corrects the assist command value based on the output of the fuzzy inference means.

[0029]

According to the invention of claim 1, the steering torque, the vehicle speed,
Fuzzy inference is performed according to a predetermined fuzzy rule using the steering angular velocity and the steering angular acceleration as input parameters, and the inertia compensation gain and the viscosity compensation gain are calculated. Then, the inertia compensation value and the viscosity compensation value correct the inertia compensation value and the viscosity compensation value, respectively. Therefore, the gain correction according to the steering state is performed by the fuzzy inference, and the steering performance is improved.

According to the second aspect of the invention, fuzzy inference is performed according to a predetermined fuzzy rule using the steering torque, the vehicle speed, the steering angular velocity, and the steering angular acceleration as input parameters, and the assist command value is corrected. That is, the current command value to the motor is directly corrected by the fuzzy inference result. Therefore, similarly, the assist command correction according to the steering state is performed by the fuzzy inference, and the steering performance is improved.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 and 2 are views showing an embodiment of an electric power steering apparatus according to the invention of claim 1. FIG. 1 is a block diagram functionally showing the entire apparatus. In the description of FIG. 1, the same components as those of the conventional example are designated by the same reference numerals, and duplicate description will be omitted.

In FIG. 1, reference numeral 70 denotes a fuzzy operation function unit (fuzzy inference means), which is a fuzzy operation function unit 70.
Steering angular velocity dθ / dt and steering angular acceleration d ² θ / d
The t ² , the steering torque V _T, and the vehicle speed V _S are input as input parameters.

The steering angular velocity dθ / dt is detected by the steering angular velocity detection / calculation means (steering angular velocity detection means) 35, and the steering angular acceleration d ² θ / dt ² is detected by the steering angular acceleration detection / calculation means (steering angular acceleration detection). Means 44), the steering torque V _T is detected by a torque sensor (steering torque detecting means) 21, and the vehicle speed V _S is detected by a vehicle speed sensor (vehicle speed detecting means) 22.

The fuzzy arithmetic function unit 70 operates the steering angular velocity dθ.
/ Dt, steering angular acceleration d ² θ / dt ² , steering torque V _T and vehicle speed V _S as input parameters, fuzzy inference is performed according to a predetermined fuzzy rule, and acceleration positive feedback gain (inertia compensation gain) Ka and speed negative feedback gain Ka (Viscosity compensation gain) Kv is calculated, and the inertia control unit 40 is operated.
And to the respective multiplication calculation units 42 and 32 of the viscosity control unit 30.

Acceleration positive feedback gain (inertia compensation gain) K
a is multiplied by the command value output from the inertia compensation value instruction function unit 41 in the multiplication operation unit 42 of the inertia control unit 40. Then, this multiplication result is added to the reference current command value output from the assist command unit 20.

On the other hand, the velocity negative feedback gain (viscosity compensation gain) Kv is multiplied by the command value output from the viscosity compensation value instruction function unit 31 in the multiplication operation unit 32 of the viscosity control unit 30. The result of this multiplication is the viscosity command output command unit 3
3 is subtracted from the reference current command value output from the assist command unit 20.

The steering angular velocity detecting means may be, for example, a tacho generator or an encoder, or an observer for estimating the steering angular velocity may be provided instead of the sensor. This observer estimates the steering angular velocity based on the terminal voltage of the motor 6 and the armature current, or based on the current command value to the motor 6 and the measured armature current. Further, the steering angular acceleration detection means may be calculated by differentiating the steering angular velocity.

Here, the fuzzy rule of each compensation gain calculation will be described. FIG. 2 (A) is a membership function of the antecedent part in each compensation gain calculation. Steering torque V _T , motor speed (that is, steering angular speed) dθ / d
t, motor acceleration (that is, steering angular acceleration) d ² θ /
It uses dt ² as an input parameter. Also, FIG.
(B) is a membership function of the antecedent part, which uses the vehicle speed V _S as an input parameter. Of course, the membership function of the antecedent part is not limited to the triangular shape, and it is needless to say that the membership function of any other shape may be adopted.

FIG. 2C shows a fuzzy output in the consequent part, which is a membership function represented by a single tone position, and the compensation gains Ka and Kv are output values. Although the fuzzy output is represented by a single tone position here, the present invention is not limited to this, and may be represented by a membership function of, for example, a triangle or another shape.

The meaning of the label in each membership function is as follows. PL: Positive Large PS: Positive Small ZR: Zero Neutral NS: Negative Small NL: Negative Large

The fuzzy rules are shown in Table 1 below.

[0042]

[Table 1]

The fuzzy rule is expressed by the following equation. The rule is so-called IF, THEN (if
If) is expressed in the form of. The fuzzy rule R1 will be described as a typical example as follows. R1. _{IF V S = PL, V T} = ZR, dθ / dt = PL AND d 2 θ / dt 2 = ZR THEN fuzzy output (Ka) = ZR fuzzy outputs (Kv) = PL

The fuzzy rule R1 is "if the vehicle speed is high, the steering torque is zero (neutral), the motor speed (that is, steering angular speed) is large in the positive direction, and the motor acceleration (that is, steering angular acceleration) is zero ( In the case of neutral, the inertia compensation gain Ka as a fuzzy output is zero, and the viscosity compensation gain Kv as a fuzzy output is large in the positive direction. ” Hereinafter, other rules are determined by the same method.

The basic idea of the fuzzy rule shown in Table 1 is to fuzzy estimate the start of turning the steering wheel or the start of returning when the steering wheel is released. In this case, the inertia compensation gain K
On the other hand, a is increased, and on the other hand, the neutral point of the steering wheel when the steering wheel is released and returned while running is fuzzy estimated, and in this case, the viscosity compensation gain Kv is increased.

The fuzzy operation function unit 70 may be realized by using a binary digital computer, or may be realized by a digital or analog type fuzzy processor having an architecture dedicated to fuzzy inference operation.

Description of Operation Next, the operation of the power steering control will be described. When the ignition switch is turned on, a normal power assist process is first executed, and as a result, vehicle speed sensitive control, that is, assist force is controlled according to the torque sensor input so that it is light in the low speed range and heavy in the high speed range. .

On the other hand, at the beginning of turning the handle 1 or at the beginning of returning when the handle 1 is released, the state is fuzzy estimated by the fuzzy calculation function unit 70, and the inertia compensation gain Ka and the viscosity compensation gain Kv are calculated to calculate the inertia. It is output to each multiplication calculation unit 42, 32 of the control unit 40 and the viscosity control unit 30. Then, the inertia compensation gain Ka
Is multiplied by the command value output from the inertia compensation value instruction function unit 41 in the multiplication calculation unit 42 of the inertia control unit 40, and the multiplication result is added to the reference current command value output from the assist command unit 20.

The viscosity compensation gain Kv is calculated by the viscosity control unit 3
In the multiplication calculation unit 32 of 0, the viscosity compensation value indicating function unit 31
Is multiplied by the command value output from the reference command value output from the assist command section 20 via the viscosity command output command section 33. In this way, the assist force is finally corrected and controlled.

Specifically, the evaluation by the membership function shown in FIG. 2, that is, the steering torque V _T , the motor speed (steering angular speed) dθ / dt, and the motor acceleration (steering angular acceleration) d ² θ / dt ² are calculated. The degree of matching with the membership function as an input parameter is evaluated, and the fuzzy logic operation is executed according to the fuzzy rules shown in Table 1.

In the fuzzy logic operation process, the above-mentioned input parameters are given in the antecedent part of the fuzzy logic, the degree of conformity to the corresponding membership function of the fuzzy rule is determined, and the one with a small degree of conformity is selected and the consequent is selected. In the consequent part, the membership function of the output is limited by the selected fitness in the consequent part to obtain, for example, a trapezoidal membership function.

Then, the membership function is MAX
A composite output is generated by superimposing the composite output, and then the defuzzifier sets the center of gravity of the composite output as the definite output, and each compensation gain K corresponding to the estimated value of the steering state.
a and Kv are non-linearly compensated and calculated, and inertia compensation and viscosity compensation control are corrected by these gains.

For this reason, the start of turning the steering wheel or the start of returning the steering wheel when the steering wheel is released is effectively fuzzy estimated, and the inertia compensation gain Ka is increased to reduce the inertia feeling at the start of turning the steering wheel. In addition, the returning speed when the handle is released can be improved, and the convergence can be enhanced. On the other hand, the neutral point of the steering wheel when the steering wheel is released while traveling is also fuzzy estimated, and the viscosity compensation gain Kv increases. Therefore, it is possible to improve the damping characteristic of the convergence when the handle is released.

As described above, the acceleration positive feedback gain Ka of the inertia control unit 40 and the speed negative feedback gain K of the viscosity control unit 30.
Since v is calculated by fuzzy inference, the speed response can be improved while avoiding oscillation of the control system by the optimum inertia compensation gain Ka, and the stability (damping property) can be obtained by the optimum viscosity compensation gain Kv. It is possible to improve the steering performance by suppressing the generation of unnecessary viscous feeling during normal steering while ensuring the above.

Next, FIGS. 3 and 4 are views showing an embodiment of the electric power steering apparatus according to the invention of claim 2. FIG. 3 is a block diagram functionally showing the entire apparatus. In the description of FIG. 3, the same components as those of the conventional example will be denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 3, reference numeral 80 denotes a fuzzy operation function unit (fuzzy inference means), which is a fuzzy operation function unit 80.
Steering angular velocity dθ / dt and steering angular acceleration d ² θ / d
The t ² , the steering torque V _T, and the vehicle speed V _S are input as input parameters.

The fuzzy calculation function unit 80 calculates the steering angular velocity dθ.
/ Dt, steering angular acceleration d ² θ / dt ² , steering torque V _T and vehicle speed V _S as input parameters, fuzzy inference is performed according to a predetermined fuzzy rule, and inertia / viscosity compensation value K
av is calculated and added to the reference current command value output from the assist command unit 20. That is, in this embodiment, the current command value is directly corrected by the fuzzy calculation,
The configuration is so-called fuzzy hybrid control.

Here, the fuzzy rule of the inertia / viscosity compensation value Kav calculation will be described. In this case, the membership function of the antecedent part is the same as that shown in FIGS. 2A and 2B described above (not shown), and only the membership function of the consequent part is different. Fig. 4 shows the fuzzy output of the membership function in the consequent part, which is the membership function expressed by the single tone position, and the inertia / viscosity compensation value K
The output value is av.

The fuzzy rules are shown in Table 2 below.

[0060]

[Table 2]

The fuzzy rule is expressed by the following equation. The rule is so-called IF, THEN (if
If) is expressed in the form of. The fuzzy rule R1 will be described as a typical example as follows. R1. IF V _S = PL, V _T = ZR, dθ / dt = PL AND d ² θ / dt ² = ZR THEN Fuzzy output (Kav) = NL

The fuzzy rule R1 is "if the vehicle speed is high, the steering torque is zero (neutral), the motor speed (that is, steering angular speed) is large in the positive direction, and the motor acceleration (that is, steering angular acceleration) is zero ( In the case of neutral), the inertia / viscosity compensation value Kav as a fuzzy output is large in the negative direction. ” Hereinafter, other rules are determined by the same method.

The basic idea of the fuzzy rule shown in Table 2 is to fuzzy-estimate the start of turning the steering wheel or the start of returning when the steering wheel is released. In this case, the inertia / viscosity compensation value Kav is made positive, while The neutral point of the steering wheel when the steering wheel is released is fuzzy estimated, and in this case, the inertia / viscosity compensation value Kav is made negative.

In the above-described structure, in the present embodiment, when the handle 1 is turned off or returned when the handle 1 is released, the state is fuzzy estimated by the fuzzy operation function unit 80, and the inertia / viscosity compensation value Kav is calculated. Then, the reference current command value output from the assist command unit 20 is added.

For this reason, the inertial / viscosity compensation value K is set especially at the beginning of turning the handle or returning when the handle is released.
When av becomes a positive value and is added to the reference current command value, it is possible to reduce the feeling of inertia when the steering wheel is turned off, and it is possible to improve the returning speed when the steering wheel is released and improve the convergence. Further, the neutral point of the steering wheel when the steering wheel is released while the vehicle is traveling is fuzzy estimated, and the inertial / viscosity compensation value Kav becomes a negative value, so that it is possible to improve the damping characteristic of the convergence when the steering wheel is released.

[0066]

According to the first aspect of the present invention, since the inertia compensation gain and the viscosity compensation gain are calculated by fuzzy reasoning, the optimum inertia compensation gain avoids oscillation of the control system and speed response. Can also increase
It is possible to improve the steering performance by suppressing the generation of unnecessary viscous feeling during normal steering while ensuring stability (damping property) by the optimum viscosity compensation gain.

According to the second aspect of the invention, since the assist command value is calculated by fuzzy inference,
Similarly, the optimum inertia / viscosity compensation value can improve the speed response while avoiding oscillation of the control system, while ensuring stability (damping property) while avoiding unnecessary viscous feeling during normal steering. It is possible to suppress the occurrence and improve the steering performance.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an embodiment of an electric power steering apparatus according to the invention of claim 1.

FIG. 2 is a diagram showing a membership function of the same example.

FIG. 3 is a functional block diagram of an embodiment of the electric power steering apparatus according to the invention of claim 2.

FIG. 4 is a diagram showing a membership function of the same example.

FIG. 5 is a diagram showing an example of a conventional power steering mechanical system.

FIG. 6 is a functional block diagram of a conventional power steering device.

FIG. 7 is a diagram showing characteristics of assist torque of a conventional power steering device.

[Explanation of symbols]

1 Steering Handle 6 Motor 20 Assist Command Unit 21 Steering Torque Sensor (Steering Torque Detection Unit) 22 Vehicle Speed Sensor (Vehicle Speed Detection Unit) 30 Viscosity Control Unit (Motor Viscosity Control Unit) 35 Steering Angular Velocity Detection / Calculation Unit (Steering Angular Velocity Detection Unit) 40 Inertia Control Section (Inertial Control Means) 44 Steering Angular Acceleration Detection / Calculation Means (Steering Angular Acceleration Detection Means) 60 Current Control Sections 70, 80 Fuzzy Calculation Function Section (Fuzzy Inference Means) 100 Control Means

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B62D 137: 00

Claims (2)

[Claims] 1. A motor connected to a steering system for generating a steering assist torque, a steering torque detecting means for detecting a steering torque of the steering system, a vehicle speed detecting means for detecting a vehicle speed, and a steering angular velocity of the steering system. Steering angular velocity detecting means for detecting, steering angular acceleration detecting means for detecting steering angular acceleration of the steering system, and inertial control for calculating an inertia compensation value for compensating the inertia of the motor based on the output of the steering angular acceleration detecting means. Means, a viscosity control means for calculating a viscosity compensation value for compensating the viscosity of the motor based on the output of the steering angular velocity detection means, and a drive of the motor based on the outputs of the steering torque detection means and the vehicle speed detection means. Electric power comprising: control means for calculating an assist command value and correcting the assist command value with the inertia compensation value and the viscosity compensation value. In the tearing device, fuzzy inference is performed according to a predetermined fuzzy rule using the steering torque, the vehicle speed, the steering angular velocity, and the steering angular acceleration as input parameters, and the inertia compensation gain of the inertia control means and the viscosity compensation gain of the viscosity control means are calculated. Fuzzy inference means is provided, the inertia control means corrects the inertia compensation value based on the output of the fuzzy inference means, and the viscosity control means corrects the viscosity compensation value based on the output of the fuzzy inference means. An electric power steering device characterized by: 2. A motor connected to a steering system for generating a steering assist torque, a steering torque detecting means for detecting a steering torque of the steering system, a vehicle speed detecting means for detecting a vehicle speed, and a steering angular velocity of the steering system. Steering angular velocity detecting means for detecting, steering angular acceleration detecting means for detecting steering angular acceleration of the steering system, and inertial control for calculating an inertia compensation value for compensating the inertia of the motor based on the output of the steering angular acceleration detecting means. Means, a viscosity control means for calculating a viscosity compensation value for compensating the viscosity of the motor based on the output of the steering angular velocity detection means, and a drive of the motor based on the outputs of the steering torque detection means and the vehicle speed detection means. Electric power comprising: control means for calculating an assist command value and correcting the assist command value with the inertia compensation value and the viscosity compensation value. In the tearing device, the steering torque, the vehicle speed, the steering angular velocity, the steering angular acceleration is used as an input parameter, fuzzy inference is performed according to a predetermined fuzzy rule, and a fuzzy inference unit that calculates a correction value for correcting the assist command value is provided, The electric power steering apparatus, wherein the control means corrects the assist command value based on the output of the fuzzy inference means.