JPH0714718B2 - Motor control device for electric power steering device - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a motor control device for an electric power steering device that applies an auxiliary steering force (power assist) by a motor drive to a steering system of a vehicle.

[Prior art]

As a motor control device for an electric power steering device as described above, a vehicle speed sensor for detecting a vehicle speed and a steering angle sensor for detecting a steering angle are provided in addition to a torsion torque sensor for detecting a torsion torque of a steering system. The command signal based on the output of the torque sensor is corrected based on the output of the vehicle speed sensor so as to decrease with the increase of the vehicle speed, and the return signal that increases with the increase of the steering angle is added from the output of the steering angle sensor. The applicant of the present invention has already proposed a method for controlling the rotating direction and rotating torque of the electric motor (see Japanese Patent Laid-Open No. 61-98675).

[Problems to be Solved by the Invention]

By the way, in the conventional motor control device for the electric power steering device as described above, the automatic return to the neutral position of the steering wheel is limited to the traveling of the vehicle, and the stationary operation can only be lightened when the vehicle is parked or stopped. For this reason, it is difficult to know whether the steering wheel is displaced from the neutral position. Further, when the vehicle is parked with the vehicle displaced, there is a problem in that the operability is poor, for example, the driver can start without knowing it and hurry to re-steer. Therefore, the present invention is capable of automatically returning the steering wheel to the neutral position when the vehicle is parked and parked. At that time, the steering wheel is not affected by disturbances such as changes in the friction coefficient μ of the tire ground contact road surface and changes in the vehicle weight. An object of the present invention is to provide a motor control device for an electric power steering device that rotates gently from beginning to end and has a good feeling and safety.

[Means for Solving the Problems]

For this purpose, a motor control device for an electric power steering device according to the present invention includes a torsion torque sensor that detects a torsion torque of a steering system, a vehicle speed sensor that detects a vehicle speed,
An electric power steering apparatus comprising: a steering angle sensor that detects a steering angle; and a drive control unit that controls a rotation direction and a rotation torque of an electric motor for power assist according to a command signal based on an output signal of each sensor. A neutral position return command unit that outputs a return signal as a command signal for automatically returning the steering wheel to the neutral position when the vehicle is parked or parked. The neutral position return command unit inputs signals from the vehicle speed sensor and the torsion torque sensor. , When both values are substantially zero, it is determined that the vehicle is parked or stopped, and the neutral position return determination unit that passes the signal of the actual steering angle detected by the steering angle sensor, and the actual position that has passed the neutral position return determination unit Input a rudder angle signal and gradually reduce it from the initial value of the actual rudder angle within a predetermined time with the passage of time to output a target value for the return of the rudder angle with a characteristic close to zero. Then, by inputting the return target value signal from the return target value setting unit and the actual steering angle signal that has passed through the neutral position return determination unit, the deviation amount of the actual steering angle with respect to the return target value is calculated and the deviation amount is calculated. The deviation amount calculation unit that signals and the deviation amount from the deviation amount calculation unit are input as a signal, and the absolute value of the deviation amount increases within a predetermined value with respect to the increase of the absolute value of the deviation amount. And a return torque value instruction function unit that outputs a return signal having a characteristic that the absolute value becomes constant when the value exceeds.

[Action]

With such a means, when the vehicle is parked or parked, the detected values of the torsion torque sensor and the vehicle speed sensor become substantially zero, and the neutral position return determination unit in the neutral position return command unit outputs the signal of the actual steering angle detected by the steering angle sensor. Let it pass. Therefore, the return target value setting unit inputs a signal of the actual steering angle, and outputs a target return value of the steering angle having a characteristic that gradually decreases from its initial value within a predetermined time and approaches zero to the deviation amount calculation unit. Further, the deviation amount calculation unit inputs the return target value signal and the actual steering angle signal that has passed through the neutral position return determination unit, and outputs the deviation amount of the actual steering angle with respect to the return target value as a signal. Then, the return torque value instruction function unit, which has input the deviation amount signal, has a constant absolute value within a range in which the absolute value of the deviation amount exceeds a predetermined value as the absolute value of the deviation amount decreases. When the absolute value falls within a predetermined value, a return signal having a characteristic that the absolute value gradually decreases with respect to the absolute value of the deviation amount and approaches zero is output as a command signal.
By inputting this command signal to the drive control unit, the rotation direction and the rotation torque of the electric motor for power assist are controlled, and the steering wheel is automatically returned to the neutral position. Here, the neutral position return command unit that automatically returns the steering to the neutral position sets the return target value by the return target value setting unit to a characteristic that gradually decreases from the initial value of the actual steering angle with time and approaches zero. At the same time, the actual steering angle signal is fed back to the deviation amount calculation unit to calculate the deviation amount from the return target value, and this deviation amount is input to the return torque value instruction function unit, whereby the return torque value instruction function unit The return signal is output based on the characteristic function. According to the return torque value instruction function unit, when the deviation amount is less than or equal to a predetermined value, when the deviation amount decreases, a return signal that gradually decreases and approaches zero is output, and when the deviation amount exceeds a constant value. It outputs the return signal of. By adopting the control with such characteristics, the steering wheel smoothly returns to the neutral position within a certain period of time regardless of the turning angle (the turning speed is large, the rotation speed is fast, and the steering angle is small. And), the feeling is good. Further, even if the influence of disturbance such as a change in the friction coefficient μ of the tire contact road surface or a change in the vehicle weight is large and the deviation amount between the set target return value and the actual steering angle becomes large, the deviation amount The feedback control controls the rotation of the steering wheel to stop if the actual steering angle exceeds the return target angle according to the amount of deviation, or to accelerate the steering wheel rotation if the actual steering angle is insufficient for the return target angle. Therefore, there is no inconvenience that the return signal becomes too large and hunting occurs, and good control can be realized in terms of stability.

【Example】

An embodiment of the present invention will be specifically described below with reference to the drawings. In FIG. 1, reference numeral 1 is an electric motor for power assist, which is connected to a pinion shaft of a rack and pinion mechanism of a steering system (not shown) via a speed reducer, a joint, etc., and can provide an assist force to the steering system. It is like this. Such an electric motor 1 includes a positive / negative determination unit 21, an absolute value conversion unit 22, a duty control unit 23, an armature current detection unit 24,
With the drive control unit 2 including the electric motor drive unit 25,
The rotation direction and the rotation torque are controlled based on a command signal described later. That is, the command signal is input to the positive / negative determination unit 21 and the absolute value conversion unit 22, and the determination signal of the positive / negative determination unit 21 is input to the electric motor drive unit 25, whereby the direction of the motor current is switched according to the command signal. Controlled and absolute value converter
The output signal of 22 is input to the duty control unit 23 to determine the duty ratio, and by inputting this to the electric motor drive unit 25, the rotation torque according to the magnitude of the command signal is set. The rotation torque of the electric motor 1 is converged to a constant instruction value by the armature current detection unit 24 detecting the armature current of the electric motor 1 and feeding back the detected value to the duty control unit 23. Controlled by. Here, in order to output a command signal to the drive control unit 2, in the present embodiment, an assist command unit 3, a return command unit 4, a phase compensation command unit 5, a steering angle phase compensation command unit 6, a neutral position return command. A section 7 is provided. The assist command unit 3 basically generates an assist signal according to the magnitude and direction of the torsion torque of the steering system, and includes a torsion torque sensor 31 for detecting the direction and the magnitude of the torsion torque, and this torsion torque. Based on the output voltage signal of the sensor 31 (see FIG. 2), basically, the assist signal having the characteristic as shown by the solid line in the graph of FIG. However, an assist torque value instruction function unit 32 is provided that outputs an assist signal that increases or decreases according to the value of the torsion torque with a polarity according to the direction of the torsion torque when the value exceeds a predetermined value. Further, the assist command section 3 is provided with a vehicle speed sensor 33 for detecting the speed of the vehicle, and based on the output voltage signal of the vehicle speed sensor 33, the assist command section 3 decreases as the vehicle speed increases as shown in the graph of FIG. The addition constant function unit 34 for generating the addition constant signal Sv having the characteristics described above, and the addition calculation unit 35 for inputting the addition constant signal Sv and the output signal of the torsion torque sensor 31 and outputting the same to the assist torque value instruction function unit 32. Is provided. The addition calculation unit 35 adds and subtracts the addition constant signal Sv according to the polarity of the output signal of the torsion torque sensor 31, so that the characteristic shown in the graph of FIG. 3 has the vehicle speed as a parameter in the X-axis direction. It is designed to be translated. That is, to show an example of the characteristics in the case of right-turning, as shown by the solid line in FIG.
For the same output, the absolute value of the output decreases as the vehicle speed increases, and for the same vehicle speed, the absolute value of the output increases as the absolute value of the torsion torque increases. A multiplication constant function unit 36 and a multiplication calculation unit 37 are provided to correct such output characteristics as shown by the broken line in FIG. 5 according to the vehicle speed. This multiplication constant function unit 36 is a multiplication constant signal having the characteristic shown in FIG. 6 based on the output voltage signal of the vehicle speed sensor 33, that is, the multiplication constant is 1 when the vehicle speed is 0, and the constant gradually increases as the vehicle speed increases. Generates a multiplication constant signal having a characteristic of decreasing as 0 approaches 0. The multiplication calculation unit 37 multiplies the output of the assist torque value instruction function unit 32 by the multiplication constant, and the assist signal it from the multiplication calculation unit 37 corresponds to the vehicle speed as shown in FIG. As shown by the broken line. Further, the assist torque it may be a map instruction in which torque and vehicle speed are input values. Next, the return command unit 4 generates a return signal in the direction of returning the steering angle to the neutral (straight) position according to the turning angle of the steering system. For example, a rack in a rack and pinion mechanism of the steering system. Steering angle sensor 41 for detecting a steering angle based on the amount of movement of the steering wheel, and a return torque value indicating function for outputting a return signal iθ having the characteristic shown in the graph of FIG. 7 based on the output voltage signal of the steering angle sensor 41. The unit 42 is provided. The phase compensation command section 5 receives the output signal of the torsion torque sensor 31 and outputs a signal proportional to the differential value thereof, and based on the output signal of the phase compensation section 51, for example, as shown in FIG. The phase compensation instruction function unit 52 for outputting the assist auxiliary signal ia having the characteristics shown in the graph is provided, and in this embodiment, the output signal of the phase compensation unit 51 is further added to the output signal of the torsion torque sensor 31 to perform addition calculation. Entered in part 35,
Affects the input signal to the assist torque value instruction function unit 32. Further, the steering angle phase compensation command unit 6 generates an attenuation signal in a direction opposite to the direction in which the rudder moves in accordance with the speed of the steering operation. The output signal of the rudder angle sensor 41 is input and the differential value thereof is input. Based on the force signal of the steering angle phase compensating unit 61, which outputs a signal proportional to the steering angle phase compensating unit 61, for example, a steering angle phase compensating instruction function that outputs a damping signal i having the characteristic shown in the graph of FIG. And a section 62. Here, the neutral position return command unit 7 generates a return signal in that automatically returns the steering to the neutral position when the vehicle is parked or stopped, and the output voltage from the steering angle sensor 41 is returned to the neutral position. Vehicle speed discriminating unit 71 as a discriminating unit,
A deviation amount calculation unit 74 and a return target value setting unit 75, which are respectively input via the torsion torque determination unit 72 and the time limit unit 73,
A return torque value instruction function unit 76, which receives a signal from the deviation amount calculation unit 74, is provided. The vehicle speed determination unit 71 outputs the output voltage signal from the steering angle sensor 41 as it is only when the vehicle speed becomes substantially zero based on the output signal of the vehicle speed sensor 33, and otherwise regulates the output. ing. Further, the torsion torque discriminating unit 72
Outputs the signal from the vehicle speed discrimination unit 71 as it is only when the torsion torque is substantially zero (for example, 0.3 kgf or less at the handle end) based on the output signal of the torsion torque sensor 31, and otherwise regulates the output. It is like this. Further, the time limiter 73 outputs the signal from the torsion torque discriminating unit 72 and then outputs the signal only for 5 seconds, for example. On the other hand, the return target value setting unit 75 stores the initial steering angle θo based on the steering angle signal initially input from the time limiting unit 73, and multiplies this by the predetermined multiplication constant f (t) which is a time function. The target return value θc is set. Here, the multiplication constant f (t) is
As shown in FIG. 10, the characteristic is such that it gradually decreases from 1 to 0 with the lapse of time (t). Therefore, θc = θo · f
The return target value θc represented by (t) gradually approaches zero as time elapses (a predetermined time within 5 seconds corresponding to the time limiter 73 in this embodiment). Next, the deviation amount calculation unit 74 compares the actual steering angle θ based on the steering angle signal from the time limit unit 73 with the return target value θc from the return target value setting unit 75, and the deviation amount (θc−θ) Is output to the return torque value instruction function unit 76. In this case, both θc and θ take a positive value in the right turning area and a negative value in the left turning area. The return torque value instruction function unit 76 outputs a return signal in having the characteristic shown in the graph of FIG. 11 according to the deviation amount (θc−θ). That is, it is a positive value (right turning direction) in the left turning area where the deviation amount (θc−θ) is a positive value, and a negative value (left turning direction) in the right turning area where it is a negative value. Then, when the absolute value of the deviation amount (θc−θ) is within a predetermined value, the absolute value increases proportionally, and when it exceeds the predetermined value, a return signal in which the absolute value becomes constant is output. Further, in this embodiment, the return signal iθ from the return command unit 4 and the attenuation signal i from the steering angle phase compensation command unit 6 are used.
A vehicle speed determination unit 8 that regulates the output of the vehicle is provided. The vehicle speed discriminating unit 8 inputs the addition signal of the return signal i and the attenuation signal i, and outputs the addition signal as it is when the vehicle speed is 5 km / h or more based on the output signal of the vehicle speed sensor 33. When the vehicle speed is 5 km / h or less, the output of the addition signal is regulated. Then, under the regulation of the vehicle speed determination unit 8, the assist signal it from the assist command unit 3, the assist auxiliary signal ia from the phase compensation command unit 5, and the return signal iθ from the return command unit 4, Damping signal i from the steering angle phase compensation command unit 6
And a return signal in from the neutral position return command unit 7 are output to the drive control unit 2 as a command signal. In the above configuration, when a twisting torque is generated in the steering system due to the steering operation, the twisting torque sensor 31 detects this and generates an output signal, but at this time, the vehicle speed sensor 33 and the steering angle sensor 41 Correction is added to the assist signal it based on the above output signal by each of the above information. Then, the rotation direction and the rotation torque of the electric motor 1 are controlled through the positive / negative determination of the assist signal it and the duty ratio control according to the absolute value. Here, the relationship between the torsion torque and the assist signal it is basically as shown in the graph of FIG. 3. For example, a positive assist signal corresponds to the torsion torque when turning right. It is output so that it increases with the increase of. Therefore, the electric motor 1 is rotationally driven with an output torque according to the magnitude of the torsion torque in the rotation direction that assists the right turning, and the steering force at the time of the right turning is reduced. When turning left, the electric motor 1 is controlled in a rotation direction that assists turning left based on a negative assist signal.
Works the same as in the case of right cutting. Here, the functional characteristics of the torsion torque and the assist signal change based on the output signal of the vehicle speed sensor 33 in this embodiment.
For example, in FIG. 5 showing the characteristic graph of the assist signal with respect to the right-handed torsion torque, when the state of the vehicle speed is 0 is represented by Mo, as the vehicle speed increases to V ₁ and V ₂ , the addition constant function unit 3
On the basis of the addition processing of the addition constant signal Sv from 4, the characteristic graph changes in parallel with M ₁ and M _{2 in} the X-axis direction of FIG. Then, the characteristic graph M _{1 is obtained} by the multiplication processing of the multiplication constant signal.
Changes to m ₁ and M ₂ decreases to m ₂ . Therefore, when the magnitudes of the torsion torques are the same, the magnitude of the assist signal decreases as the vehicle speed increases. This is
This means that the output torque of the electric motor 1 with respect to the same torsional torque decreases as the vehicle speed increases. While the vehicle is traveling at low speed, sufficient power assist can be obtained, but the steering force becomes excessive during traveling at high speed. Therefore, there is no fear that the steering wheel is too light when steering. On the other hand, the steering angle sensor 41 detects the steering angle along with the steering operation, and based on this, the characteristic shown in FIG. 7, that is, the steering angle 0 is not output in the vicinity of the neutral position, and this range is It increases proportionally in the range of the left and right steering angles ± θo, and becomes a constant value when it exceeds ± θo. It is a negative value in the right-turning region (left turning direction) and a positive value in the left-turning region. A return signal i.theta. That is in the (right cutting direction) is output. Further, when the turning speed is fast, such as when the vehicle travels on a curve with a small radius with a sharp steering wheel, the turning angle θ changes abruptly, which is detected by the steering angle phase compensator 61.
A damping signal i is output from the steering angle phase compensation indicator function unit 62 based on the detection signal. This is the characteristic shown in FIG. When the vehicle speed is 5 km / h or more, the return signal iθ and the damping signal i are added by the action of the vehicle speed determination unit 8 so as to decrease the assist signal it when the steering wheel is steered in the direction in which the absolute value of the steering angle increases. To be Therefore, there is no fear that the steering wheel will be too light when turning suddenly. Further, for example, when the steering is held at the right turning angle θ ₁ , a positive assist signal it based on the output signal of the above-described torsion torque sensor 31
And a negative return signal iθ based on the output signal of the steering angle sensor 41.
_The electric motor 1 is controlled by the addition signal with 1. If the graph of the assist signal it is shown by the solid line in FIG. 3, the addition signal is shown by the broken line. Therefore, when the steering holding state of the right turning angle θ ₁ is released, the torsional torque T is drastically reduced and the addition signal immediately becomes a negative value (left turning direction) along the broken line in FIG. 3. As a result, a torque is generated in the left-turning direction in the electric motor 1 to cancel the frictional force of the reducer and the moment of inertia of the motor. Therefore, when the vehicle is running (5 km / h or more) In addition to the effect, the steering system can be smoothly restored to the straight traveling state, and the steering wheel returning operation becomes good. Then, as the turning angle θ decreases, the magnitude of the return signal iθ gradually decreases to approach 0, and when the turning angle returns to the neutral position, the torque of the electric motor disappears. On the other hand, when the steering wheel returns from a sharp turn (high G turn),
The handle may exceed neutral due to the inertia of the motor.
However, when the damping signal i is output from the steering angle phase compensation command unit 6, the damping signal commands an output torque opposite to the rotation direction of the steering wheel, so that the steering wheel does not return too much, and the steering wheel is released when the vehicle is traveling at high speed. The convergence property from is also improved. Next, the steering operation in the stopped state of the vehicle, that is, the stationary steering will be described. In this case, since the ground resistance is large, the torsion torque sharply increases with the steering operation, and the output voltage of the torsion torque sensor 31 also increases. Increase rapidly in proportion. Then, the tendency of the torsional torque to increase rapidly is detected by the phase compensator 51 of the phase compensation commander 5, and the output signal corresponding to the degree of increase of the torsional torque is added to the output signal of the torsional torque sensor 31. Therefore, even when the torsion torque T is small and the accompanying assist signal it is not yet generated, if the degree of change in the torsion torque is large, the assist signal it
Is immediately output, the electric motor 1 is immediately started without delay in response during stationary steering, and self-excited vibration is prevented from occurring. And at the time of stationary steering, the vehicle speed is 5 km / h or less,
The return signal iθ of the return command unit 4 and the damping signal i from the steering angle phase compensation command unit 6 are regulated by the vehicle speed determination unit 8, so that light steering without energy labor is realized. Further, when an output signal is issued from the phase compensator 51,
The phase compensation instruction function unit 52 outputs an assist auxiliary signal ia having the characteristic shown in FIG. That is, the degree of change of the torsional torque is proportionally increased / decreased within a predetermined value, and when it exceeds the predetermined value, the assist assist signal ia which becomes a constant value is immediately output according to the direction of change of the torsional torque. Therefore, when repeating left and right steering, etc., the assist auxiliary signal ia
Is immediately output to absorb the inertial force when the electric motor 1 is started and stopped. Now, control when the vehicle is parked or stopped will be described with reference to the flowchart of FIG. First, the vehicle speed discriminating unit 71 discriminates whether or not the vehicle speed has become substantially zero (the set value has hysteresis) (S1). If YES, the torsion torque discriminating unit 72 subsequently makes the torsion torque substantially zero. It is determined whether or not (S2). If YES here, it is determined that the driver has no intention to steer and the vehicle is parked and stopped, and the process proceeds to the next step (S3), but NO at steps (S1) and (S2).
In the case of, the neutral position return command unit 7 is reset (S
Four). In step (S3), the time limit unit 73 determines whether or not the time is within a predetermined time (5 seconds), and if the predetermined time has elapsed and the result is NO, the process ends. When the predetermined time has elapsed, the neutral position return command unit 7 does not restart unless either the vehicle speed or the torque exceeds the predetermined value. If YES here, the following control is performed only within that time. That is, the deviation amount calculation unit
The actual steering angle θ is input to the 74 and the return target value setting unit 75 (S5), and the return target value θc is set by the return target value setting unit 75.
Is set (S6). Next, the deviation amount (θc-
θ) is calculated (S7). Based on this, the return signal in is output from the return torque value instruction function unit 76 (S8). With this kind of control, if you park or stop while in the steered state,
The return signal in based on the output signal of the steering angle sensor 41 drives the electric motor 1 for a predetermined time (5 seconds), and the steering automatically returns to the neutral position. At that time, even if the initial turning angle is large, the return target value θc is not zero from the beginning but gradually approaches zero, and the actual steering angle θ follows this, so the deviation amount (θc−θ ) Is a value whose absolute value is relatively small. For this reason, the return signal in also has a relatively small absolute value, and the steering wheel rotates gently from beginning to end to automatically return to a good feeling and safety. In addition, even when the tires hit an obstacle and cannot steer when automatically returning to the neutral position when parking or stopping like this,
After the elapse of a predetermined time, the return signal disappears and the driving of the electric motor 1 is stopped, so that the electric motor 1 is not damaged by overload.

【The invention's effect】

As described above, according to the present invention, when the vehicle is parked or stopped, the neutral position return command unit outputs a return signal for returning the steering to the neutral position as a command signal, and the command signal is input to the drive control unit. The steering is automatically returned to the neutral position by controlling the rotation direction and rotation torque of the electric motor for power assist. Therefore, the steering can be performed safely and reliably when the vehicle restarts. Here, the neutral position return command unit sets the return target value by the return target value setting unit to a characteristic that gradually decreases from the initial value of the actual steering angle with time and approaches zero.
The actual steering angle signal is fed back to the deviation amount calculation unit to calculate the deviation amount from the return target value, and this deviation amount is input to the return torque value instruction function unit to obtain the characteristic function in the return torque value instruction function unit. Based on this, a return signal is output. According to this return torque value instruction function unit, when the deviation amount is less than or equal to a predetermined value, a return signal is output which proportionally gradually decreases and approaches zero when the deviation amount decreases, and the deviation amount is set to a predetermined value. When it exceeds, a return signal of a constant value is output. By adopting the control of such a characteristic, the return target value is set to a characteristic that gradually decreases with time and approaches zero within a predetermined time.
The steering can automatically return to the neutral position within the same time regardless of the size of the initial rudder angle, the steering wheel rotates gently from beginning to end to provide a good feeling and safe operation, and there is no vibration near the neutral position and damping is possible. Good control of can be realized. Furthermore, even if the influence of disturbance such as a change in the friction coefficient μ of the tire contact road surface or a change in the vehicle weight is great due to the feedback control, and the deviation amount between the set return target value and the actual steering angle remains large. Since the return signal that matches the return target value is output according to the deviation amount, there is no inconvenience that the return signal becomes too large and hunting occurs, and good control can be realized in terms of stability. .

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention, and FIG.
The figure shows the characteristic graph of the output signal of the torsion torque sensor, FIG. 3 shows the basic characteristic graph of the assist signal, FIG. 4 shows the characteristic graph of the addition constant signal, FIG. 5 shows the characteristic change of the assist signal, and FIG. Is a characteristic graph of a multiplication constant signal, FIG. 7 is a characteristic graph of a return signal, FIG. 8 is a characteristic graph of an assist assist signal, FIG. 9 is a characteristic graph of an attenuation signal, FIG. 10 is a characteristic graph of a multiplication constant, and FIG. FIG. 11 is a characteristic graph of the return signal, and FIG. 12 is a flowchart showing the operation of the neutral position return command unit. 1 ... Electric motor 2 ... Drive control unit 21 ... Positive / negative discrimination unit, 22 ... Absolute value conversion unit 23 ... Duty control unit, 24 ... Armature current detection unit 25 ... Electric motor drive unit 3 ... Assist command unit 31 …… Torsion torque sensor, 32 …… Assist torque value instruction function unit, 33 …… Vehicle speed sensor, 34 …… Addition constant function unit, 35
…… Addition calculation unit, 36 …… Multiplication constant function unit, 37 …… Multiplication calculation unit 4 …… Return command unit 41 …… Steering angle sensor, 42 …… Return torque value instruction function unit 5 …… Phase compensation command unit 51 ...... Phase compensation unit, 52 …… Phase compensation instruction function unit 6 …… Steering angle phase compensation command unit 61 …… Steering angle phase compensation unit, 62 …… Steering angle phase compensation instruction function unit 7 …… Neutral position return command unit 71 ... Vehicle speed discriminating unit, 72 ... Torsional torque discriminating unit, 73 ... Time limit unit, 74 ... Deviation amount calculating unit, 75 ... Return target value setting unit, 76 ... Return torque value instruction function unit 8. … Vehicle speed discriminator.

Continuation of the front page (56) References JP 61-1579 (JP, A) JP 60-80967 (JP, A) JP 60-15268 (JP, A) JP 55-76760 (JP , A) JP 62-283069 (JP, A) Actually developed 58-142180 (JP, U)

Claims (1)

[Claims] 1. A torsion torque sensor for detecting a torsion torque of a steering system, a vehicle speed sensor for detecting a vehicle speed, and a steering angle sensor for detecting a steering angle, which are responsive to a command signal based on an output signal of each sensor. In the electric power steering device that controls the rotation direction and rotation torque of the electric motor for power assist by the drive control unit, a return signal that automatically returns the steering to the neutral position when the vehicle is parked or stopped is output as a command signal. A neutral position return command unit is provided, and the neutral position return command unit inputs signals from the vehicle speed sensor and the torsion torque sensor, and when the values of both are substantially zero, it is determined that the vehicle is parked or stopped and the steering angle sensor detects it. Input the actual steering angle signal that has passed the neutral position return determination unit that passes the signal of the actual steering angle and the neutral position return determination unit, and within the predetermined time from the initial value of the actual steering angle. And a return target value setting unit that outputs a return target value of the steering angle with a characteristic that gradually decreases and approaches zero with the passage of time, a return target value signal from the return target value setting unit, and the neutral position return determination. The deviation amount calculation unit that inputs the actual steering angle signal that has passed through the section, calculates the deviation amount of the actual steering angle with respect to the return target value, and outputs the deviation amount as a signal, and the deviation amount signal input from the deviation amount calculation unit. However, with respect to the increase of the absolute value of the deviation amount, the absolute value of the deviation amount increases within a predetermined value, the absolute value increases, and the absolute value becomes constant when the absolute value of the deviation amount exceeds the predetermined value. A motor control device for an electric power steering device, comprising: an instruction function unit.