JPS62231870A - Electrically driven power steering device - Google Patents

Abstract

PURPOSE:To reduce the effect due to the moment of inertia of an electric motor so as to improve steering feeling by computing a correction value related to the moment of inertia by a correction value computing means based on rotating angular acceleration. CONSTITUTION:A detected steering torque signal DT, a detected car speed signal DV, and a detected steering angle signal Dtheta are inputted into a control device 13. And the control circuit 20 of the control device 13 including an A/D converter 21, a microcomputer 22, and a D/A converter 23 corrects a reference current value I1 determined based on both of the detected steering torque and car speed, using a correction value C computed depending on steering angular acceleration for computing a target current value I2. When the target current value I2 becomes negative by the correction, the steering is assisted to the direction opposite to the steering by means of an electric motor 9. Owing to this constitution, even when the rotating angular acceleration of the motor 9 is great, the effect due to the moment of inertia of the motor 9 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric power steering device in which steering force is assisted by the output of an electric motor.

[Prior art]

As a prior art of this type of electric power steering device, for example, there is a technique previously filed by the present applicant and described in Japanese Patent Application No. 173033/1982.

This device includes an electric motor connected to a steering system that generates a steering assist torque, a steering torque detecting means for detecting the steering torque of the steering system, and a reference steering assist torque based on a detected steering torque value of the steering torque detecting means. a reference steering assist torque calculation means for calculating the steering angular acceleration of the steering system, a steering angular acceleration detection means for detecting the steering angular acceleration of the steering system, and a correction value related to the moment of inertia based on the steering angular acceleration detection value of the steering angular acceleration detection means. a torque correction value calculation means for calculating, an actual steering assist torque calculation means for calculating an actual steering assist torque by adding the calculation results of the reference steering assist torque calculation means and the calculation results of the torque correction value calculation means; It is characterized by comprising a drive means for converting the calculation result of the steering assist torque calculation means into a drive current value for the electric motor and outputting it to the electric motor, the rotational angular acceleration of the electric motor, that is, the rotational angle of the steering column shaft. The acceleration is calculated by the second derivative of the detected steering angle value, and the steering assist torque is corrected according to the calculated steering angle acceleration, thereby compensating for the output torque that decreases due to the moment of inertia of the electric motor. This allows the steering sensation to be optimally controlled.

[Problem that the invention seeks to solve]

However, in the electric power steering device as the prior art, the assist direction of the steering assist torque (rotation direction of the electric motor) is determined only by the detected steering torque value, so when the steering direction is reversed, etc. However, when the rotational angular acceleration of the electric motor is large, the target rotational position can be controlled by the moment of inertia of the electric motor itself, and a sufficient correction effect cannot be obtained. .

The present invention has been made by focusing on the inadequacies of the prior art, and, when the moment of inertia of the electric motor is large, by actively rotating the electric motor in the opposite direction to the steering direction, The purpose is to reduce the influence of the moment of inertia of the electric motor to solve the above-mentioned inadequacies.

(Means for Solving the Problems) In order to achieve the above object, the present invention, as shown in the basic configuration diagram of FIG. a steering torque detection means for detecting the steering torque of the system and outputting a steering torque detection signal; a running state detection means for detecting the running state of the vehicle and outputting the running state detection signal; and the steering system or the electric motor. rotational angular acceleration detection means for detecting the rotational angular acceleration of and outputting the rotational angular acceleration detection signal; and reference current value calculation means for calculating a reference current value based on the steering torque detection signal and the driving state detection signal. a correction amount calculation means for calculating a correction amount related to the moment of inertia based on the rotational angular acceleration detection signal; a target current value calculation means for calculating a target current value by calculating the reference current value and the correction amount; A drive means for outputting the target current value as a drive current value of the motor so as to drive the motor in a direction opposite to the direction of the rotational angular acceleration when the target current value becomes a negative value. It is said that

[Effect]

According to the present invention, an electric motor that generates a steering assist torque is connected to a steering system, a steering torque detecting means detects the steering torque of the steering system, a running state detecting means detects the running state of the vehicle, and The rotational angular acceleration detection means detects the rotational angular acceleration of the steering system or the electric motor, and the reference current value calculation means calculates the reference current value based on the detected steering torque and running condition, and the reference current value is calculated based on the detected rotational angular acceleration. The correction amount calculating means calculates the correction amount related to the moment of inertia, calculates the target current value by calculating the correction amount and the reference current value, and when the target current value becomes a negative value, the driving means steers the electric motor in the direction. By controlling the drive in the opposite direction,
Improves steering feel by suppressing fluctuations in steering assist torque due to the moment of inertia of the electric motor.

〔Example〕

The present invention will be explained below based on illustrated embodiments.

FIG. 2 to FIG. 4 are diagrams showing an embodiment of the present invention.

First, to explain the structure, 1 shown in FIG. 2 is a steering shaft, and this steering shaft 1 is composed of an upper shaft 1a and a lower shaft lb that are connected via a universal joint 2. Upper shaft 1a
A steering wheel 3 is fixed to the upper end, and a pinion shaft 5 is connected to the lower end of the lower shirt +-ib via a universal joint 4, and the pinion provided at the lower end of the pinion shaft 5 is used for steering. It meshes with the rack of the rack shaft 7 inside the gear box 6. The above-mentioned steering wheel 3, steering shaft 1, universal joints 2, 4, pinion shaft 5, and
The steering shaft 7 constitutes a steering system.

The above-described shaft 5 is connected to a rotating shaft 9a of an electric motor 9 via a reduction gear mechanism 8. This reduction gear mechanism 8 includes drive gears 8b that mesh with each other within a casing 8a.
The driven gear 8C is fixed to the pinion shaft 5, and the drive gear 8b is fixed to the rotating shaft 9a. The electric motor 9 is composed of, for example, a DC servo motor, and includes an electromagnetic clutch 9b and a rotating shaft 9a.
The rotational force is transmitted to the reduction gear mechanism 8 via.

Further, the steering shaft 1 is provided with a steering torque sensor 10 as a steering torque detecting means for detecting the steering torque input to the steering shaft l. The steering torque sensor 10 is constructed of, for example, a strain gauge fixed to the steering shaft 1, and is configured to detect an analog voltage according to the magnitude and direction of twisting that occurs in the steering shaft l when the driver steers the steering wheel 3. The steering torque detection signal D becomes
Output T.

Reference numeral 11 denotes a vehicle speed sensor which is a specific example of a driving state detecting means, and detects, for example, the rotational speed of the output shaft of a transmission, and generates a vehicle speed detection signal D consisting of a pulse signal with a period corresponding to this.
Outputs V.

Reference numeral 12 denotes a steering angle sensor serving as a steering angle detection means for detecting a steering angle, and includes, for example, a disc with a slit attached to the steering shaft 1 and a disc 2 facing the slit.
It is composed of a rotation detector including a photocoupler having a set of detectors, and outputs a steering angle detection signal Dθ which is a pulse signal according to the rotation direction and rotation speed of the steering shaft 1.

Reference numeral 13 denotes a control device as a control means, which is connected to a power source 40 such as a battery. Which side door device 13 is
As shown in FIG. 3, a steering torque detection signal DT from the steering torque sensor 10, a vehicle speed detection signal DV from the vehicle speed sensor 11, and a steering angle detection signal Dθ from the steering angle sensor 12 are supplied. Control signals 31 to S3 for controlling the electric motor 9 based on the control signals 31 to S3 and! It is composed of a control circuit 20 that outputs a control signal S4 for controlling the magnetic latch 9b, and a motor drive circuit 30 that is supplied with the control signals 81 to S3 and drives the electric motor 9 based on the control signal S4.

The control circuit 20 includes two A/D converters, a microcomputer 22, and a D/A converter 23.

The microcomputer 22 includes at least an input circuit 22a and an output circuit 22b as an interface circuit, an arithmetic processing unit 22c, and a storage device 22d. The input circuit 22a is connected to the above-mentioned steering torque sensor ]0
The steering torque detection signal DT of the vehicle speed sensor 11 is supplied via the A/D transformer 21, and the vehicle speed detection signal DV of the vehicle speed sensor 11 is
and the steering angle detection signal Dθ of the steering angle sensor 12 are directly supplied, and a motor current control signal Sl corresponding to the steering assist torque is outputted from the output circuit 22b via the D/A converter 23. Direction control signals Sz, Si and clutch opening/closing control signal S4 are directly output.

The arithmetic processing unit 22c determines a reference current value It based on the steering torque detection signal DT and vehicle speed detection signal DV supplied to the input circuit 22a, and executes predetermined arithmetic processing when the reference current value 11 is not zero. to determine the target current value r2 and the assist direction (direction of action of the steering assist torque), and thereby output the motor control signal 31 that controls the drive of the electric motor 9. When the reference current value 11 is zero, the electric motor The generation of the steering assist torque by 9 is stopped, so that steering can be performed only by manual operation.

The storage device 22d also stores a processing program necessary for the calculation processing of the calculation processing device 22C, a storage table representing the relationship between the steering torque T and the reference current value 11 using the vehicle speed ■ as a parameter, and a correction 1c related to the moment of inertia. It stores a correction value k for calculating , and sequentially stores the calculation results of the calculation processing unit 122c.

The motor drive circuit 30 includes a pulse width modulation circuit 32 to which the motor control signal Sl output from the control circuit 2o and a current feedback signal from the current detector 31 that detects the load current of the motor 9 are input, and its modulation output. and AND gates 33 and 34 to which the clockwise rotation signal S2 and counterclockwise rotation signal S3 from the control circuit 20 are individually supplied, and these AN
It is comprised of a forward/reverse drive circuit 35 to which the outputs of the D gates 33 and 34 are supplied.

The pulse width modulation circuit 32 is composed of, for example, a differential amplifier, a sawtooth wave generation circuit, and a comparison circuit, and the motor control signal Sl and the current feedback signal are supplied to the differential amplifier, and the differential amplifier The output and the sawtooth wave signal from the sawtooth wave generation circuit are supplied to a comparison circuit, and the comparison output is outputted as the output of the pulse width modulation circuit 32. Further, the forward/reverse drive circuit 35 is composed of, for example, two switching transistors, and each switching transistor is individually supplied with the outputs of the two AND gates 33 and 34, and the collector of each switching transistor is connected to the motor. They are individually connected to the clockwise rotation terminal and the counterclockwise rotation terminal of No. 9, respectively, and chopper-control the motor drive current.

Next, the operation of the above embodiment will be explained with reference to FIG. 4 showing the processing procedure in the arithmetic processing unit 22C.

The process shown in FIG.
c) is executed as a timer interrupt process at each interval.

First, in step (2), the steering torque detection signal DT from the steering torque sensor 10 is read and temporarily stored as the steering torque detection value T in a predetermined storage area of the storage device 22d.

Next, proceeding to step (2), the vehicle speed detection signal DV from the vehicle speed sensor 11 is read, the number of pulses per unit time or the pulse interval is calculated to calculate the vehicle speed, and this is set as the vehicle speed detection value (2) in the storage device 22d. Temporarily stored in a predetermined storage hl area.

Next, the process moves to step (3), where the steering angle detection signal Dθ from the steering angle sensor 12 is read, the steering direction and steering angle are determined, and these are stored in the storage device as a steering direction detection value and a steering angle detection value θ. The data are temporarily stored in the respective predetermined storage areas of 22d.

Next, the process moves to step (2), and based on the detected steering angle value θ stored in step (2), the steering angle acceleration is calculated by second-order differentiation, and this is set as the detected steering angle acceleration value θ in the storage device 1! ! It is temporarily stored in a predetermined storage area of 22d. Here, the detected steering angular acceleration value σ corresponds to the rotational angular acceleration of the electric motor 9 by multiplying it by the gear ratio of the reduction gear mechanism 8 in the steering system.

Next, proceeding to step (2), the steering torque detection value T stored in the step (2) and the vehicle speed detection value (2) stored in the step (2) are read out, and the steering torque using the vehicle speed previously stored in the storage device 22d as a parameter is obtained. - With reference to the reference current value conversion table, search and determine the reference current value 11 (=f (T, V)l) corresponding to the detected steering torque value T.

Next, the process moves to step (2), and it is determined whether the reference current value (1) determined in step (2) is O. The determination in this case is to determine whether or not to apply the steering assist torque by the electric motor 9 to the steering system, and the steering torque T
When it is 0, it becomes It-0, and in this case, it is determined that the steering assist torque is unnecessary, and the process moves to step (2).

In this step (2), a control signal S4 with a logic value "0" for turning off the electromagnetic clutch 9b from the output circuit 22b is outputted to the electromagnetic clutch 9b, and a steering direction control signal S2. S3 is output to the motor drive circuit 30, and the interrupt processing is thus ended.

In this way, when the control signal S4 with the logical value "0" is supplied to the electromagnetic clutch 9b, the electromagnetic clutch 9b is turned off, and the connection state between the electric motor 9 and the reduction gear mechanism 8 of the steering system is released. Then, the steering assist torque by the electric motor 9 to the steering system is not transmitted, and the wheels are steered only by the steering angle of the steering wheel 3 by the driver.

At this time, the motor drive circuit 30 receives the steering direction image signal S2. Since S3 has the logical value "0", the output of the AND game) 33, 34 maintains the logical value "0", and therefore, the forward/reverse drive circuit 35 maintains the off state, so the current of the motor 9 decreases. The supply circuit is cut off, and the electric motor 9 is kept in a stopped state.

On the other hand, if the determination result in step (2) is If≠0, it is determined that the steering assist torque from the electric motor 9 is necessary, and the process proceeds to the next step (2).

In this step (2), a control signal S4 of logical value "1" is supplied to the electromagnetic clutch 9b. As a result, the electromagnetic clutch 9b is turned on, the electric motor 9 and the reduction gear mechanism 8 are connected, and the steering assist torque by the electric motor 9 is applied to the steering system.

Next, the process proceeds to step (2), where the steering angular acceleration θ calculated in step (2) and the correction value stored in advance in the storage device 22d are read out, and the absolute value of the steering angular acceleration υ is calculated. The correction amount C is calculated by multiplying the angular acceleration entertainment value 1θ1 and the correction value by.

Next, the process moves to step 0, and it is determined whether the steering angular acceleration σ calculated in step (2) is greater than O. The determination in this case is to check whether the steering direction is to the right. When σ≦0, it is determined that the steering direction is to the left and the process moves to step 0, while when θ>0, the steering direction is to the right. It is determined that it is steering and moves to step [phase].

In these step ■ and step [phase], step ■
It is determined whether or not the stored steering torque T is greater than O. The determination in this case is to see whether the direction of action of the steering torque is to the right or to the left.
When T<0, it is determined that the vehicle is being steered to the left, while when T>0, it is determined that the vehicle is being steered to the right. As a result, when the judgment results of steps ■ and 0 are in the same direction as the judgment direction of step [stock], the process moves to step 0 and step 0, respectively, while each judgment result is in the same direction as the judgment direction of step [phase]. When the direction is opposite, the process moves to step 0 and step [phase], respectively.

In step @ and step [phase], the reference current value 11 determined in step (2) and the correction amount C calculated in step (2) are read out, and the correction amount C is added to the reference current value II to obtain the target current value. Calculate each I2. After this step @, move to step [phase] and output circuit 2
The counterclockwise rotation control l signal S] from 2b is set to a logical value “1”,
Further, after step 0, the process moves to step 0, and the clockwise rotation control signal S2 is set to the logical value "l".

In addition, in the above step ① and step [phase], the reference current value 11 and the correction Ic are read out similarly to steps @ and 0, but in this case, the correction amount C is read out from the reference current value 11.
The target current value I2 is calculated by subtracting . After this step 0, it moves to step 0, and then step [
After [phase], the process moves to step ■.

In these steps [phase] and step ■, step 0
And it is determined whether the target current value I2 calculated in step [phase] is greater than O. In this case, the determination is made to see whether the rotation direction of the electric motor 9 is the same as the steering direction or the opposite direction, and when I2 is 0, the electric motor 9 is rotated in the opposite direction to the direction in which the steering torque is applied. It is determined that the target current value ■2 is to be driven, moves to step ■ and step [phase], and changes the target current value ■2 with the absolute value of the value calculated in step ◎ and step [phase], respectively. , in step [phase], transition to the step [phase] and set the counterclockwise rotation control signal S to the logical value "1", while
In step [phase], the process moves to step 0, and the clockwise rotation control signal S2 is set to the logical value "1".

On the other hand, each determination result of step [phase] and step 0 is 1
When 2>0, it is determined that the electric motor 9 is to be rotationally driven in the same direction as the direction of action of the steering torque, and step [
phase], the process moves to step @, and the clockwise rotation control signal S
2 is set to the logic value "1", while in step 0, the process moves to the same step [phase] as the step [phase] described above, and the counterclockwise rotation control signal S3 is set to the logic value "1".

Next, proceed to step O, and perform the steps @, ■,
The target current value I2 set as either 0 or @ is outputted from the output circuit 22b to the D/A converter 23 as the motor drive control signal Sl. In this way, the motor control signal Sl
When is output, this is converted into an analog current by the D/A converter 23, and this is supplied to the motor drive circuit 30. Therefore, in the motor drive circuit 30, assuming that the electric motor 9 is in a stopped state, Since the detection signal of the load current detector 31 that detects the load current is 0, a pulse modulation signal with a large duty ratio (the width of the on state is larger than the width of the off state) is output from the pulse width modulation circuit 32. This will be output, and this will be supplied to AND game 1-33.34.

At this time, assuming that the driver is turning the steering wheel 3 to the left, it is determined that 6≦O in step [Standard], and T<0 in the next step ■, so the next step ], the correction amount C calculated in step ■ is added to the reference current value 11 determined in step ■ to calculate the target current value ■2, and in the next step [phase], the counterclockwise rotation control signal S3 is output. be done.

In this way, when the left rotation control signal S3 is output from the output circuit 22b, an output corresponding to the pulse modulation signal is obtained from the AND gate 34, and as a result, the electric motor 9 is rotated through the operation of the forward/reverse drive circuit 35. Start turning left. As a result, the rotational torque of the electric motor 9 is transmitted to the pinion shaft 5 of the steering system via the electromagnetic clutch 9b and the reduction gear mechanism 8, and the left and right steering wheels are steered to the left through the operation of the rack-and-pinion steering gear. be done.

At the same time, when the electric motor 9 starts rotating, the load current detection value of the load current detector 31 increases, so the duty ratio of the pulse modulation signal from the pulse width modulation circuit 32 decreases, and eventually the electric motor 9 is connected to the control circuit 20. It is rotationally driven so as to add to the steering system a steering assist torque corresponding to the steering torque T outputted from the vehicle speed (2) and the vehicle speed (2).

Next, from the above-mentioned left-turning state to the rudder-holding state (υ−〇).

TkuO: The steering torque in this case is a force directed to the left that resists the self-lining torque. ), it is determined that θ≦0 in step 0, and T<0 in the next step ■.
Therefore, step [phase] is passed through step 0.
At step @, the counterclockwise rotation control signal S3 is output, but at step @, the target current value ■2 becomes substantially O, and this target current value I2
is output from the output circuit 22b as a motor control signal Sl.

As a result, the electric motor 9 becomes non-rotating, and the left and right steered wheels maintain their current steered states.

After that, when the steering wheel 3 is turned back to the right, the determination of step [phase] changes to θ>0, so the next step shifts to step [phase], but the determination of step @ also changes to T>0. Therefore, the next step [phase] is moved to step 0, where the correction amount C is added to the reference current value II to calculate the target current value 12, and in the next step 0, the correction amount C is added to the reference current value II. A clockwise rotation control signal S3 in the opposite direction to [phase] is output.

In this way, when the clockwise rotation control signal S2 is output from the output circuit 22b, the AND gate 33 outputs a pulse change! J! l
An output corresponding to the signal is obtained, and the electric motor 9 starts to rotate clockwise through the operation of the forward/reverse rotation drive circuit 35. As a result, the rotational torque of the electric motor 9 is transmitted to the pinion shaft 5 of the steering system via the electromagnetic clutch 9b and the reduction gear mechanism 8, and the left and right steering wheels are steered to the right through the operation of the rank-and-pinion steering gear. be done.

At the time of such steering reversal, if the holding state is not held at all or the period of time is extremely short and the rotational inertia moment of the electric motor 9 is large, the rotational direction of the electric motor 9 and the steering direction of the steering wheel 3 are opposite directions. A situation arises. In this way, if the steering direction of the steering wheel 3 changes to the right even though the rotating direction of the electric motor 9 is to the left, it is determined that θ≦0 in step [phase], and T>O is determined in the following step Therefore, the process moves to step (2) and the reference current value 1. The correction ff1C is subtracted from the target current value I2, and the next step [
phase], the target current value I2 is positive or negative (+2
>O) is determined.

At this time, if the determination result of step [phase] is 12>0, that is, if the reference current value ■l is larger than the correction 1c, the process moves to step @ so that the rotational direction of the electric motor 9 matches the steering direction. The clockwise rotation control signal S2 from the output circuit 22b is set to logical value "1". Therefore, in this case, the electric motor 9 is rotated in the same direction as the steering direction as usual, and the normal steering assist torque by the electric motor 9 is added to the steering system.

On the other hand, when the determination result of step [share] is summer 2, that is, when the target current value I2 becomes a negative value because the correction amount C is larger than the reference current value Il, the electric motor 9
Step [
phase] and the counterclockwise rotation control signal S from the output circuit 22b.
3 is the logical value "1". Therefore, in this case, the electric motor 9 is rotationally driven in the opposite direction to the steering direction, so that the influence of the rotational inertia moment of the electric motor 9 during steering can be corrected, and a good steering feeling can be obtained. be able to.

Note that when steering to the right, the action is only in the opposite direction from the above embodiment, and the processing contents are the same.

That is, to briefly explain the contents, it is determined that θ>0 at step 0 due to right steering, and the following step [phase]
Since it is determined that T>O, the process moves to step [phase] via step 0, and the clockwise rotation control signal S2 from the output circuit 22b is set to the logical value "1". After that, when you stop steering to the right and turn back to the left, at step [phase] 6≦
0, and in the following step (2) it is determined that T<0. Therefore, the process moves to step [phase] via the step 0, and the counterclockwise rotation control signal S3 from the output circuit 22b is set to the logical value "
1”.

During this steering reversal, it is determined that θ>0 in step [phase],
When it is determined that T<0 in the next step [phase], the process moves to step ■ via step [phase], and step [phase]
It will be determined whether the target current value I2 calculated in is positive or negative, and depending on the determination result, the process will proceed to the step 0 or the same step [phase] as the step [phase], In this way, the same steering assist torque control as in the case of the left-hand rudder described above is performed.

The rotational angular acceleration detection means is configured in the process of step (2) above, the reference current value calculation unit is configured in the process of step (2), the correction amount calculation unit is configured in the process of step (2), and the correction amount calculation unit is configured in the process of step (2).
[phase], ■, @, @, @ and @ constitute the target current value calculation means, and further, the steps [phase], [phase],
The processing of (1), (2), I6, and [phase] and the motor drive circuit 30 constitute a drive means.

In this embodiment, the reference current value I! is determined based on the detected steering torque and vehicle speed. is corrected by the correction amount C calculated according to the steering angular acceleration to obtain the target current value I2.
At this time, when the target current value I2 becomes a negative value due to the above correction, the electric motor 9 assists in steering in the opposite direction to the steering direction, so that the rotational angular acceleration of the electric motor 9 is Even if the electric motor 9
By reducing the influence of the moment of inertia, it is possible to always obtain a suitable steering assist torque, thereby improving the steering feel.

In the above embodiment, a case has been described in which the microcomputer 22 is used as the control circuit 20, but the invention is not limited to this, and it may be configured by combining electronic circuits such as a logic circuit, a comparison circuit, and a function generation circuit. You can also. Furthermore, although the correction amount C determined in step (2) in FIG. The calculation may be performed by adding the absolute value of angular acceleration 1θ1.

Further, in the above embodiment, a case has been described in which the vehicle speed sensor 11 is applied as the driving state detecting means, but the present invention is not limited to this. A lateral acceleration detection sensor or the like that detects acceleration can be applied, and the same effects as in the above embodiment can also be obtained.

Furthermore, as the rotational angular acceleration detection means, in the above embodiment, an example was explained in which a value obtained by second-order differentiating the steering angle of the steering shaft that constitutes the steering system is used. A value similar to the above-mentioned steering angular acceleration can also be obtained by detecting the rotation angle of and performing second-order differentiation of the rotation angle.

Furthermore, in the above embodiment, an example was explained in which a plurality of spur gears were applied as a reduction gear mechanism, but it is of course possible to apply various reduction gears such as a worm gear, a worm wheel, and a plurality of helical gears. be.

〔Effect of the invention〕

As described above, according to the present invention, the reference current value determined based on the steering torque and vehicle speed is corrected by the correction amount calculated according to the steering angular acceleration to calculate the target current value. In this case, if the target current value becomes a negative value due to the above correction, the electric motor is rotated in the opposite direction to the steering direction and steering assist torque is added in the opposite direction. Even when the steering angular acceleration is large, such as when the steering angle is high, the influence of the moment of inertia of the electric motor on steering can be reduced, and fluctuations in the steering torque can be effectively suppressed. Therefore, it is possible to always obtain a suitable steering assist torque depending on the driving state of the vehicle, and thereby it is possible to obtain the effect that a good steering feeling can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of this invention, FIG. 2 is a schematic configuration diagram showing an embodiment of this invention, FIG. 3 is a block diagram showing an example of a control device according to this invention, and FIG. 4 1 is a flowchart showing an example of a processing procedure of the arithmetic processing device. 1... Steering shaft, 5...
Binion shaft, 8...Reduction gear mechanism, 9.
...Electric motor, 9b...Electromagnetic clutch, 1
0... Steering torque sensor (steering torque detection means), 11... Vehicle speed sensor (driving state detection means)
, 12... Steering angle sensor, 13... Control device, 20... Control circuit, 22...
Microcomputer, 30...Motor drive circuit Figure 2

Claims (1)

[Claims] an electric motor connected to a steering system that generates a steering assist torque, a steering torque detection means that detects the steering torque of the steering system and outputs a steering torque detection signal, and detects the running state of the vehicle and the running state. a running state detection means for outputting a detection signal, a rotational angular acceleration detection means for detecting the rotational angular acceleration of the steering system or the electric motor and outputting the rotational angular acceleration detection signal, and detecting the steering torque detection signal and the running state. a reference current value calculation means that calculates a reference current value based on the signal; a correction amount calculation means that calculates a correction amount related to the moment of inertia based on the rotational angular acceleration detection signal; and a correction amount calculation means that calculates the reference current value and the correction amount. a target current value calculating means for calculating a target current value; An electric power steering device comprising: a drive means for outputting a drive current value as a drive current value.