JP2002104210A - Controller for electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for electric power steering device to perform an MA-MT control in case no or little steering torque is sensed, assuring a good returning characteristic of the steering wheel during low-speed running and good convergence during high-speed running. SOLUTION: A target steering torque setting part 32 of a CPU(central processing unit) 21 sets a target steering torque Th* on the basis of the steering angle θ and car speed V, while a current command value calculation part 31 calculates the assist current command value I on the basis of the steering torque Th, target steering torque Th*, and the current Im of a motor 6. A convergence control part 81 of the CPU 21 calculates the target converging current Ihd* on the basis the steering angle θ and car speed V. Normally the CPU 21 makes a drive control of the motor 6 on the basis of the assist current command value I, and when the value of steering torque Th remains small and a hand-off judgement is made, the motor 6 is put in drive control on the basis of the value obtained by adding the target converging current Ihd* to the assist current command value I.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric power steering device for applying an assisting force by a motor to a steering system of an automobile or a vehicle.

[0002]

2. Description of the Related Art FIG. 16 schematically shows a control device relating to a conventional electric power steering device used for an automobile or the like.

A steering shaft 42 connected to a steering wheel 41 is provided with a torsion bar 43. A torque sensor 44 is mounted on the torsion bar 43. When the steering shaft 42 rotates and a force is applied to the torsion bar 43,
The torsion bar 43 is twisted according to the applied force, and the torque sensor 44 detects the twist.

[0004] A speed reducer 45 is fixed to the steering shaft 42. This reduction gear 45 has a motor 4
The gear 47 attached to the rotation shaft 6 is meshed. Further, a pinion shaft 48 is fixed to the speed reducer 45. A pinion 49 is provided at the tip of the pinion shaft 48.
Is fixed, and the pinion 49 is
Is engaged.

At both ends of the rack 51, tie rods 52 are provided.
Is fixed. Knuckles 53 are rotatably connected to both ends of the tie rod 52. A front wheel 54 is fixed to the knuckle 53. Also, Knuckle 5
3 is rotatably connected to the cross member 55.

Accordingly, when the motor 46 rotates, the rotation speed is reduced by the speed reducer 45 and transmitted to the pinion shaft 48, and transmitted to the rack 51 via the rack and pinion mechanism 50. The knuckle 53 connected to the tie rod 52 fixed to the rack 51 moves rightward or leftward according to the rotation direction of the motor 46.
The front wheel 54 is provided with a vehicle speed sensor 56.

The number of rotations and the direction of rotation of the motor 46 are determined by positive and negative assist currents supplied from a motor driving device 57. The assist current supplied by the motor driving device 57 to the motor 46 is calculated by an assist current determining unit 58 that controls the motor driving device 57. The assist current determination means 58
U and the like, and calculates the current steering torque of the steering wheel 41 from the detection signal from the torque sensor 44 and calculates the current vehicle speed from the detection signal from the vehicle speed sensor 56.

[0008] The assist current determining means 58 calculates an assist current (an assist current command value) based on the calculated steering torque and vehicle speed. This calculation is obtained from an assist map previously stored in a memory in the assist current determining means 58. Then, the assist current determining means 58 controls the current of the motor 46 for generating the assist torque so as to be the assist current (assist current command value).

However, the assist map is a value set in a specific road surface reaction force condition (for example, a flat asphalt road), and changes the road surface reaction force condition, that is, a low μ road such as a snowy road or a tire. When the air pressure drops and tire specifications (wear, tire type, etc.) change, the road surface reaction force changes, and therefore the steering force changes, leading to a deterioration in feeling.

The rise of the steering torque with respect to the steering angle (build-up feeling) is used as an index for judging the steering feeling. However, since the control device determines the assist current for the steering torque and the vehicle speed, There is a problem that it is very difficult to set map data for outputting a predetermined steering torque with respect to the steering angle (that is, for giving a feeling of buildup).

Further, when a disturbance torque due to inertia and viscosity is generated by a motor, a speed reducer, etc. during fast steering, etc., the disturbance torque cannot be canceled by the assist current determining means. Therefore, a separate control for canceling the inertia and viscosity is performed. Was needed.

Further, there is a problem that the control of the hysteresis of the steering torque when the vehicle is steered right and left cannot be set freely, and the degree of freedom for realizing an ideal steering feeling is low.

In order to solve these problems, the present applicant sets a target steering torque according to the steering angle and the vehicle speed, and sets an assist current command value based on the steering torque, the target steering torque and the motor current. A device that determines and controls a motor (hereinafter, referred to as MA-MT control) has been proposed.

That is, a steering angle sensor 59 for detecting the steering angle of the steering shaft 42 (in FIG.
The assist current determining means 58 of this device sets a target steering torque based on the steering angle from the steering angle sensor 59 and the vehicle speed.

Further, an assist current (assist current command value) is calculated based on the steering torque, the target steering torque, and the motor current of the motor 46. As a result, the target steering torque with respect to the vehicle speed and the steering angle can be set freely,
The inclination of the steering torque with respect to the steering angle can be easily set, and the adaptation of the build-up feeling is easily performed. Further, even if the road surface reaction force is reduced, or the actual steering torque is reduced or increased due to the viscosity or inertia of the motor 46 or the speed reducer 45 connected to the motor 46, the steering torque is reduced to the target steering torque. Thus, the function of adjusting the assist current (assist current command value) works, so that a stable operation feeling can be provided.

[0016]

By the way, in the above-mentioned apparatus, it is assumed that the steering wheel (the steering wheel) 41 is released by steering the steering wheel by a certain steering angle. Then, when setting the target steering torque, the target steering torque at the steering angle and the vehicle speed at that time is set. However, the steering torque (actual steering torque) becomes zero due to the release, and the assist current determining means 58 reduces the motor current for assisting the target to the target steering torque, and eventually becomes zero. Self-alignment (SA) that works on tires when the handle 41 is released
T) returns the handle 41 toward the neutral position. However, when traveling at low speed, the SAT is small, the internal friction of the electric power steering device is less than sufficient, the steering wheel 41 stops halfway, and when traveling at high speed, the SAT is large, and the inertia of the rotating body such as the motor 46 and the speed reducer 45 is large. By
Even if there is internal friction of the electric power steering device, there is a problem that the handle 51 overshoots beyond the neutral position of the handle 41 and it takes time for the handle 41 to converge to the neutral position, and the vehicle fluctuates.

Even when the steering wheel 41 is not in the neutral position, the steering torque (actual steering torque) becomes very small even when the steering wheel 41 is not released during high-speed running, and there is a region where the assist current command value by the above control becomes zero. There is a problem that the handle 41 overshoots due to the inertia of a rotating body such as 46 or the speed reducer 45, and the convergence of the handle 41 deteriorates.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to improve the steering wheel return characteristic during low-speed running in MA-MT control when steering torque is not detected or is small. Another object of the present invention is to provide a control device for an electric power steering device that improves the convergence of a steering wheel during high-speed running.

[0019]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is a control of an electric power steering apparatus having control means for controlling driving of a motor based on a motor current command value. A target steering torque setting means for setting a target steering torque based on a steering angle and a vehicle speed; and an assist current for calculating an assist current command value based on the steering torque, the target steering torque, and the motor current of the motor. Calculating means; target steering angle setting means for setting a target steering angle for returning the steering wheel to the neutral position based on the steering angle and the vehicle speed; and a target steering angular velocity based on the deviation between the target steering angle and the steering angle and the vehicle speed. Target steering angular velocity setting means to be set, and target convergence current setting means to set a target convergence current based on a deviation between the target steering angular velocity and the steering angular velocity. The target convergent current target converging current setting means is for summarized as a control apparatus of an electric power steering apparatus characterized by the motor current instruction value is added to the assist current command value.

According to a second aspect of the present invention, in the first aspect, a release determination means for determining release of the steering wheel based on the steering torque is provided, and the target convergence current setting means determines the release of the steering wheel based on the determination result of the release determination means. The output of the convergent current
A gist of the present invention is a control device for an electric power steering device that is enabled or suppressed and added to the assist current command value to obtain a motor current command value.

[0021] The invention of claim 3 is claim 1 or claim 2.
In the above, the target convergence current setting means calculates a first convergence current proportional to a deviation between the target steering angular velocity and the steering angular velocity, and further calculates a second convergence current based on an integral value of the deviation between the target steering angular velocity and the steering angular velocity. In addition, the gist of the present invention is a control device for an electric power steering device that sets a target convergence current by adding both convergence currents.

The invention of claim 4 is the invention of claim 1 or claim 2.
In the above, the target convergence current setting means calculates a first convergence current proportional to a deviation between the target steering angular velocity and the steering angular velocity, and further calculates a third convergence current based on a differential value of the deviation between the target steering angular velocity and the steering angular velocity. In addition, the gist of the present invention is a control device for an electric power steering device that sets a target convergence current by adding both convergence currents.

The invention of claim 5 is the invention of claim 1 or claim 2.
In the above, the target convergence current setting means calculates a first convergence current proportional to a deviation between the target steering angular velocity and the steering angular velocity, and calculates a second convergence current based on an integral value of the deviation between the target steering angular velocity and the steering angular velocity; Further, a gist of the present invention is a control device for an electric power steering device that calculates a third convergence current based on a differential value of a deviation between a target steering angular velocity and a steering angular velocity, and adds the convergence currents to set a target convergence current. is there.

The invention of claim 6 is the first to sixth aspects of the present invention.
In any one of the above, the neutral position includes a predetermined residual angle range, and the target steering angle setting means, when the vehicle speed is low, sets the target steering angle to return the steering wheel within the range of the residual angle. The gist of the present invention is a control device for an electric power steering device that sets the following.

(Action) According to the first aspect of the present invention, the target steering torque setting means sets the target steering torque based on the steering angle and the vehicle speed. The assist current calculation means calculates an assist current command value based on a steering torque, the target steering torque, and a motor current of the motor. The target steering angle setting means sets a target steering angle for returning the steering wheel to the neutral position based on the steering angle and the vehicle speed.

The target steering angular velocity setting means sets the target steering angular velocity based on the deviation between the target steering angle and the steering angle and the vehicle speed. The target convergence current setting means sets a target convergence current based on a deviation between the target steering angular velocity and the steering angular velocity.

The control means drives and controls the motor based on the motor current command value obtained by adding the target convergence current and the assist current command value. According to the second aspect of the present invention, the release determination means performs release determination of the steering wheel based on the steering torque. Based on the determination result of the hand-off determination means, the output of the target convergence current of the target convergence current setting means is made valid or suppressed, and the value obtained by adding to the assist current command value is used as the motor current command value. .

According to the third aspect of the present invention, the target convergence current setting means calculates the first convergence current proportional to the deviation between the target steering angular velocity and the steering angular velocity, and further calculates the integral value of the deviation between the target steering angular velocity and the steering angular velocity. , A second convergence current is calculated, and both convergence currents are added to set a target convergence current.

According to the present invention, the target convergence current setting means calculates the first convergence current proportional to the deviation between the target steering angular velocity and the steering angular velocity, and further calculates the differential value of the deviation between the target steering angular velocity and the steering angular velocity. , A third convergence current is calculated, and both convergence currents are added to set a target convergence current.

According to the fifth aspect of the present invention, the target convergence current setting means calculates the first convergence current proportional to the deviation between the target steering angular velocity and the steering angular velocity, and calculates the integrated value of the deviation between the target steering angular velocity and the steering angular velocity. A second convergence current is calculated based on the calculated convergence current, and a third convergence current is calculated based on a differential value of a deviation between the target steering angular velocity and the steering angular velocity. The convergence currents are added to set a target convergence current.

According to the invention of claim 6, the target steering angle setting means sets the target steering angle so that the steering wheel is returned within the range of the residual angle when the vehicle speed is low.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows an embodiment in which the present invention is embodied in a control device of a rack-assist type electric power steering device mounted on an automobile.
This will be described with reference to FIG.

FIG. 1 schematically shows an electric power steering apparatus. A steering shaft 2 connected to a steering wheel 1 as a handle is provided with a torsion bar 3. Note that, for convenience of explanation, the steering wheel 1 may be hereinafter referred to as a steering wheel 1. A torque sensor 4 is mounted on the torsion bar 3. When the steering shaft 2 rotates and a force is applied to the torsion bar 3, the torsion bar 3 is twisted in accordance with the applied force, and the torsion bar 3, that is, the steering torque Th applied to the steering wheel 1 is detected by the torque sensor 4. I have. Further, a steering angle sensor 17 for detecting a steering angle θ of the steering shaft 2 is mounted on the steering shaft 2. These sensor outputs are supplied to the control device 20.

A pinion shaft 8 is fixed to the steering shaft 2. A pinion 9 is fixed to the tip of the pinion shaft 8, and the pinion 9 meshes with a rack 10. The rack 10 and the pinion 9 constitute a rack & pinion mechanism 11. A tie rod 12 is fixed to both ends of the rack 10, and a knuckle 13 is rotatably connected to a tip end of the tie rod 12. This knuckle 1
A front wheel 14 as a tire is fixed to 3.
One end of the knuckle 13 is rotatably connected to the cross member 15. An electric motor (hereinafter referred to as a motor) 6 coaxially arranged with the rack 10 is a motor 6.
Is transmitted to the rack 10 via the ball nut mechanism 6a.

Therefore, when the motor 6 rotates, the number of revolutions is reduced by the ball nut mechanism 6a and the rack 1 is rotated.
0 is transmitted. And the rack 10 is a tie rod 1
2, the direction of the front wheels 14 provided on the knuckle 13 can be changed to change the traveling direction of the vehicle.

The front wheel 14 is provided with a vehicle speed sensor 16. Next, FIG. 1 shows an electrical configuration of the electric power steering device. The torque sensor 4 outputs a signal indicating the steering torque Th of the steering wheel 1. The steering angle sensor 17 outputs a steering angle signal indicating the steering angle θ of the steering shaft 2. Vehicle speed sensor 16
Outputs a detection signal corresponding to the rotation speed of the front wheels 14 indicating the vehicle speed V at that time. The control device 20 is electrically connected to a motor drive current sensor 18 for detecting a drive current (motor current Im, corresponding to the motor current value) flowing through the motor 6. A signal indicating the current Im is supplied.

The control device 20 includes a central processing unit (CPU) 21 as control means, a read-only memory (ROM).
22 and a read-only and write-only memory (RAM) 23 for temporarily storing data.

Various control programs executed by the CPU 21 are stored in the ROM 22. RAM
Reference numeral 23 temporarily stores the result of the arithmetic processing when the CPU 21 performs the arithmetic processing.

A motor driving device 24 is connected to the output side of the control device 20, and drives the motor 6 based on a control signal from the control device 20. The motor driving device 24 includes a PWM of a CPU 21 described later.
A power element (not shown) such as an FET for performing PWM control based on the calculation is provided.

The CPU 21 corresponds to target steering torque setting means, assist current calculation means, target steering angle setting means, target steering angular velocity setting means, target convergence current setting means, and release judgment means.

Next, the assist control will be described with reference to FIGS. In the following description of the functions inside the CPU 21, various parameters such as “vehicle speed V”, “steering torque Th”, and “steering angle θ” are used as meanings of corresponding signals for convenience of description. I do.

FIG. 2 is a control block diagram of the CPU 21. In this embodiment, the inside of the CPU 21 shows functions executed by a program. For example, the phase compensator 30
Represents a phase compensation function executed inside the CPU 21 instead of independent hardware. FIGS. 4 and 7
10 and 14 are control block diagrams illustrating processing functions executed by the CPU 21 according to a program.
It does not mean an actual hardware configuration.

Hereinafter, functions and operations of the CPU 21 will be described. First, for convenience of explanation, the vehicle speed sensitive assist control by MA-MT control will be described, and then the convergence control will be described.

(Vehicle speed sensitive assist control by MA-MT control) As shown in FIG.
0, 35, a current command value calculating unit 31 as an assist current determining unit, a target steering torque setting unit 32, a subtractor 33, a current control unit 34, a target steering angle setting unit, a target steering angular speed setting unit as a target steering torque setting unit, And a convergence control unit 81 as a target convergence current setting unit, a release determination unit 82 as a release determination unit, a multiplier 83, an adder 84, and the like.

The target steering torque setting section 32 inputs the vehicle speed V from the vehicle speed sensor 16 and the steering angle signal from the steering angle sensor 17, and sets the target steering torque Th *. The steering angle signal is transmitted to a target steering torque setting unit 3 via a phase compensator 35.
2 is input. That is, the phase compensator 3
Reference numeral 5 designates a phase compensation for advancing the phase of the steering angle signal output by the steering angle sensor 17, and outputs the steering angle signal to the target steering torque setting unit 32 as a steering angle θ.

More specifically, the phase compensator 35
Is, as shown in FIG. 4, a differentiator 36 and a gain multiplier 37.
And an adder 38. The differentiator 36 obtains a steering angular velocity S by differentiating the steering angle signal from the steering angle sensor 17, and the gain multiplying unit 37 supplies a value ST obtained by multiplying the steering angular velocity S by a preset gain T to an adder 38. Output. The gain T is a value obtained by a test or the like in advance so that the phenomenon that the steering torque (actual steering torque) Th for the steering angle signal does not coincide with the target steering torque Th * does not occur due to the phase delay of the steering angle signal. It is determined based on. The adder 38 adds a value ST to the steering angle signal to advance the phase (in this embodiment,
This is called the steering angle θ. ), And outputs the result to the target steering torque setting unit 32.

As shown in FIG. 5, the target steering torque setting section 32 includes a plurality of target steering torque setting maps corresponding to a plurality of predetermined vehicle speeds V different from each other. As the vehicle speed V increases, the target steering torque setting map is set such that the inclination of the target steering torque Th becomes steeper than when the vehicle speed V is low.

More specifically, a method of setting the target steering torque Th * will be described with reference to a flowchart of a target steering torque setting routine executed by the CPU 21 (see FIG. 3).
First, in S10, the steering angle θ is read, and in S11, the current steering state is right steering (steering to the right), left steering (steering to the left), or the state where the steering is maintained. In order to determine whether or not the steering angle is different, the steering angle θ is differentiated to calculate the steering angular velocity dθ / dt.

In the next step S12, when the steering angular velocity is close to zero (| dθ / dt | ≦ ε, ε is a constant that is a small value), it is determined that the steering is maintained (in S12, YES)), the steering direction determined in the previous control cycle in S17 (previous value steering direction) is set as the current steering direction, and the process proceeds to S14.

When the steering angular velocity dθ / dt is not close to zero (when it is determined “NO” in S12),
In S13, the sign of the steering angular velocity dθ / dt is checked to determine the steering direction.

Next, in S14, a target steering torque setting map relating to a vehicle speed close to the vehicle speed V is checked out of a plurality of target steering torque setting maps stored in the ROM 22 in advance for the vehicle speed V. The vehicle speeds on the map side, which are close to the vehicle speed V, are V1 and V2 (V1 ≦ V <V2).

The target steering torque setting map is shown in FIG.
As shown in (1), a target steering torque is determined for each speed corresponding to right steering and left steering. In the next S15, temporary target steering torques Th1 * and Th2 * are obtained from the retrieved target steering torque setting maps of the vehicle speeds V1 and V2 based on the steering direction determined in S13 in accordance with the steering angle θ. In S16, the target steering torque Th * with respect to the vehicle speed V and the steering angle θ is calculated by a linear interpolation formula with respect to the vehicle speed V.

The equation for the linear interpolation is as follows. Th * = (Th2 * −Th1 *) / (V2−V1) ×
(V−V1) + Th1 * Next, the current command value calculation unit 31 will be described.

The steering torque Th input from the torque sensor 4 is phase-compensated by the phase compensator 30 to enhance the stability of the steering system, and is input to the current command value calculator 31.
The vehicle speed V detected by the vehicle speed sensor 16, the motor current Im detected by the motor drive current sensor 18, and the target steering torque Th * from the target steering torque setting unit 32 are input to the current command value calculation unit 31. .

The current command value calculating section 31 is a vehicle speed sensitive assist command which is a control target value of a current supplied to the motor 6 based on the input steering torque Th, vehicle speed V, target steering torque Th *, and motor current Im. A value (corresponding to an assist current command value) I is determined.

The current command value calculator 31 includes a dead zone width setting unit 25 and a vehicle speed sensitive assist torque calculator 26 as shown in FIG. Based on the vehicle speed V, the dead zone width setting unit 25 obtains a dead zone width T0 of the steering torque that is not energized by using a dead zone width map MP stored in advance in the ROM 22, as shown in FIG. To the unit 26. Note that the dead zone width map MP is a two-dimensional map including the vehicle speed V and the dead zone width T0, and the dead zone width T0 is uniquely obtained from the vehicle speed V.

As shown in FIG. 6, the vehicle speed sensitive assist torque calculating section 26 calculates the target steering torque Th * obtained by the target steering torque setting section 32 as the dead zone width T0 (that is, in FIG. , -T0 to T0), the vehicle speed-sensitive assist command value (corresponding to the assist current command value, hereinafter referred to as an assist current command value) I is determined to be 0. , And outputs this value to the subtractor 33.

When the target steering torque Th * is out of the range of the dead zone width T0, the rack thrust calculated based on the current steering torque Th and the motor current Im, and the target steering torque Th
* The assist current command value I is set so that the rack thrust at the assist current command value I is balanced.

A method of determining the assist current command value I in the control device 20 of the electric power steering device of the rack assist type will be described below. In the case of the rack assist type, the rack thrust F at the time of the steering torque Th and the motor current Im is obtained by the following equation (A).

F = Fm + Fh (A) Here, Fm is the thrust assisted by the motor 6, and Fh is the thrust by steering the steering wheel, and can be obtained by the following equations.

Fm = 2π · Tm · ηb / L (B) Fh = 2π · Th · ηp / St (C) In the above (B), Tm represents a motor torque, and Tm = Kt × Im. … (D)

Tm is the motor torque, ηb is the ball screw efficiency of the ball nut mechanism 6a, and L is the ball screw lead. Th is the steering torque, ηp is the rack &
The rack & pinion gear efficiency, St, of the pinion mechanism 11 is its stroke ratio. Kt is a torque constant.

Therefore, by using the above equation (A), the target steering torque Th * at the vehicle speed V, the steering angle θ, and the rack thrust F at the assist current command value I (hereinafter, this thrust is referred to as F (Th *, I), and a rack thrust F at the time of the steering torque Th and the motor current Im (hereinafter, this thrust is referred to as F
(Th, Im). ) Are set equal to each other.

When F (Th *, I) = F (Th, Im),
When I is obtained by substituting the above (B), (C) and (D), the following equation is obtained. I = Im + (Th−Th *) L · ηp / (St · Kt ·
ηb) The assist current command value I thus obtained is output to the adder 84.

When the assist current command value I has the opposite sign to the target steering torque Th *, that is, reverse assist, the assist current command value I is determined to be zero and output to the adder 84.

Therefore, in this embodiment, the target steering torque Th * is set according to the steering angle θ and the vehicle speed V, and the steering torque Th, the target steering torque Th *, and the motor current I
The assist current command value I is controlled by m (MA-MT control).

The adder 84 adds the assist current command value I output from the current command value calculation section 31 by the MA-MT control and a target convergence current Ihd * calculated by the convergence control described later. The motor current command value Io is output to the subtractor 33.

The subtracter 33 outputs a signal (corresponding to an assist current control value) corresponding to the difference between the motor current command value Io input from the adder 84 and the actual motor current Im to the current control unit 34. I do.

In the present embodiment, the current control section 34 performs a known PI control, and performs feedback control based on a signal corresponding to a difference between the output of the subtracter 33 and the actual motor current Im. It is supplied to the motor drive device 24 in order. That is, the current control unit 34 performs a PWM calculation so that the motor current becomes the motor current command value Io,
The motor 6 is driven based on the calculation result. As a result, by controlling the driving of the motor 6 via the motor driving device 24, an appropriate assist force by the motor 6 can be obtained.

(Convergence Control) Next, the CPU 21 further has functions of a convergence control unit 81 and a release judgment unit 82, and these will be described.

First, the convergence control section 81 will be described.
As shown in FIG. 9, the convergence control unit 81 includes a target steering angle setting unit 86, a target steering angular velocity setting unit 87, a target convergence current setting unit 88, a differentiator 89, and subtracters 90 and 91. The vehicle speed V detected from the vehicle speed sensor 16 and the steering angle θ detected by the steering angle sensor 17 and phase-compensated by the phase compensator 35 are input to the convergence control unit 81. Then, the convergence control unit 81 determines a target convergence current Ihd * for converging the steering wheel 1 to a substantially neutral position based on the input vehicle speed V and steering angle θ.

More specifically, as shown in FIG.
The target steering angle setting unit 86 includes a sign determination unit 92, a target steering absolute angle setting unit 93, a multiplier 94, and a target steering angle calculation unit 95.

The target steering absolute angle setting unit 93 uses the target steering absolute angle setting map stored in the ROM 22 in advance based on the vehicle speed V, and calculates the absolute value of the target steering angle θ * corresponding to the vehicle speed V, that is, The target steering absolute angle | θ *** | is obtained and output to the multiplier 94. Note that the target steering angle θ * is a value for returning the steering wheel 1 to the neutral position.
The neutral position includes a predetermined residual angle range.

More specifically, the steering wheel 1 is normally used at medium to high speeds.
Is normally returned to the neutral position, that is, to 0 degrees, but it is not natural to return to 0 degrees at low speeds compared to the conventional hydraulic power steering device. Set to have a certain residual angle.

For this reason, the target steering absolute angle setting section 93
Is based on the target steering absolute angle setting map,
When the steering wheel 1 is steered, the target steering absolute angle | θ is returned from the neutral position to within a predetermined residual angle range.
*** Set |. Calculated target steering absolute angle | θ *
** | increases as the vehicle speed V decreases, and above the predetermined vehicle speed V, the target steering absolute angle | θ *** | becomes zero.

The sign judging section 92 judges a sign based on the steering angle θ, and outputs the sign signal to the multiplier 94.
That is, when the steering angle θ indicates right steering, +1 is output to the multiplier 94, while when the steering angle θ indicates left steering, − is output.
1 is output to the multiplier 94.

The multiplier 94 multiplies the sign signal from the sign judging section 92 by the target steering absolute angle | θ *** | from the target steering absolute angle setting section 93. The target steering absolute angle | θ *** | is given a sign, and the provisional target steering angle θ
It is output to the target steering angle calculation unit 95 as **.

The target steering angle calculator 95 outputs the target steering angle θ * to the subtractor 90 shown in FIG. 9 based on the provisional target steering angle θ ** and the steering angle θ. Here, specifically,
How to set the target steering angle θ * in the target steering angle calculation unit 95 will be described with reference to a flowchart of a target steering angle calculation routine executed by the CPU 21 (see FIG. 11).

First, in S21, the provisional target steering angle θ
Read **. Next, in S22, the actual steering absolute angle (ie, the value obtained by taking the absolute value of the steering angle θ) | θ | is the provisional target steering absolute angle (ie, the absolute value of the provisional target steering angle θ **). Value) | θ ** |
That is, the magnitude relationship between the provisional target steering angle θ ** and the current steering angle θ is compared.

When the current steering angle θ is closer to the neutral position than the provisional target steering angle θ **, in other words, the absolute steering angle |
If θ | is smaller than the provisional target steering absolute angle | θ ** | (| θ | <| θ ** |, ie, the determination in S22 is YE
S), and proceed to S23. Then, in S23, the actual steering angle θ is set as the target steering angle θ * (θ = θ *),
Output.

On the other hand, when the provisional target steering angle θ ** is closer to the neutral position than the current steering angle θ, ie, the absolute steering angle
| θ | is greater than or equal to the provisional target steering absolute angle | θ ** | (| θ | ≧ | θ ** |, ie, the determination in S22 is NO).
Proceeds to S24. Then, in S24, the provisional target steering angle θ ** is set as the target steering angle θ *, and (θ **
= Θ *) and output.

As shown in FIG. 9, the subtractor 90 calculates a deviation (hereinafter referred to as “steering angle deviation”) Δθ from the target steering angle θ * and the steering angle θ, and sets a target steering angular velocity setting section. 87. The target steering angular speed setting section 87 receives the steering angle deviation Δθ and the vehicle speed V, obtains a target steering angular speed Q * based on a target steering angular speed setting map stored in the ROM 22 in advance, and outputs the target steering angular speed Q * to the subtracter 91. . The target steering angular velocity setting map includes a steering angle deviation Δθ,
4 is a three-dimensional map including a vehicle speed V and a target steering angular speed Q *, and a target steering angular speed Q * is determined according to the steering angle deviation Δθ and the vehicle speed V. In the present specification, the capital letter Q is used hereinafter to mean angular velocity.

The subtractor 91 receives the target steering angular velocity Q * and the steering angular velocity Q obtained by differentiating the steering angle θ by the differentiator 89. Then, the difference (hereinafter, referred to as “steering angular velocity deviation”) ΔQ is calculated by the subtracter 91 and output to the target convergence current setting unit 88.

The target convergence current setting section 88 includes first to third convergence current setting sections 96 to 98, an integrator 99, a differentiator 100,
And an adder 101. The first convergence current setting unit 96 receives the vehicle speed V and the steering angular velocity deviation ΔQ. The first convergence current setting unit 96 calculates the first convergence current Ihd1 * using the first convergence current setting map stored in the ROM 22 in advance, and outputs the first convergence current Ihd1 * to the adder 101. The first convergence current setting map is a three-dimensional map including the steering angular velocity deviation ΔQ, the vehicle speed V, and the first convergence current Ihd1 *. Then, according to the map, according to the vehicle speed V and the steering angular velocity deviation ΔQ, a first proportional to the steering angular velocity deviation ΔQ is obtained.
Convergence current Ihd1 * is set. That is, the first convergence current Ihd1 * is output to the adder 101 by the first convergence current setting unit 96 by so-called P control.

The second convergence current setting unit 97 stores the vehicle speed V,
A steering angular velocity deviation integrated value sum_ΔQ obtained by integrating the steering angular velocity deviation ΔQ by the integrator 99 is input. The second convergence current setting unit 97 calculates the second convergence current Ihd2 * using the second convergence current setting map stored in the ROM 22 in advance, and outputs the second convergence current Ihd2 * to the adder 101. The second convergence current setting map is a three-dimensional map including the steering angular velocity deviation integrated value sum_ΔQ, the vehicle speed V, and the second convergence current Ihd2 *.
Then, according to the map, the steering angular velocity deviation integrated value sum_ΔQ according to the vehicle speed V and the steering angular velocity deviation integrated value sum_ΔQ.
Is set in proportion to the second convergence current Ihd2 *. That is, the second convergence current Ihd2 * is added to the adder 10 by so-called I control by the integrator 99 and the second convergence current setting unit 97.
1 is output.

The third convergence current setting section 98 stores the vehicle speed V,
A steering angular velocity deviation differential value d_ΔQ obtained by differentiating the steering angular velocity deviation ΔQ by the differentiator 100 is input. The third convergence current setting unit 98 calculates the third convergence current Ihd3 * using the third convergence current setting map stored in the ROM 22 in advance, and outputs the third convergence current Ihd3 * to the adder 101. The third convergence current setting map includes a steering angular velocity deviation differential value d_ΔQ, a vehicle speed V, and a third
3 is a three-dimensional map including a convergent current Ihd3 *. Then, using the same map, the vehicle speed V and the steering angular velocity deviation differential value are calculated.
According to d_ΔQ, a third convergence current Ihd3 * proportional to the steering angular velocity deviation differential value d_ΔQ is set. That is, the third
The convergence current Ihd3 * is output to the adder 101 by so-called D control by the differentiator 100 and the third convergence current setting unit 98.

The adder 101 is provided with the first to third elements.
A target convergence current Ihd * calculated by adding the convergence currents Ihd1 * to Ihd3 * is, as shown in FIG.
Output to 3.

Therefore, in this embodiment, the steering angle θ
The target steering angle θ * is set according to the vehicle speed V and the deviation between the target steering angle θ * and the steering angle θ (steering angle deviation Δθ) and the vehicle speed V
Thus, the target steering angular velocity Q * is set, and the target convergence current Ihd * is controlled by the deviation between the target steering angular velocity Q * and the steering angular velocity Q (steering angular velocity deviation ΔQ) and the vehicle speed V (hereinafter, this control is referred to as convergence control). ).

Next, the release judgment section 82 will be described. The steering release Th detected from the torque sensor 4 is input to the hand release determination unit 82. In addition, as shown in FIG. 14, the release determination unit 82 includes a release determination map. Then, using this map, the steering torque Th
Is near 0, that is, when the steering wheel 1 is lightly touched or released, "1" is output to the multiplier 83. On the other hand, when the steering torque | Th |> X (X is a constant) or more than a certain value X, “0” is output to the multiplier 83.

As shown in FIG. 2, a multiplier 83 receives and multiplies the convergence current Ihd * from the convergence control unit 81 and the output signal of “1” or “0” output from the release judgment unit 82. . Then, when the output signal from the hand-off determination unit 82 is “1”, the target convergence current Ihd * is output to the adder 84. On the other hand, when the output signal from the release determination unit 82 is “0”, a signal “0” is output.

(Flowchart of Convergence Control) Next, the CP
A flowchart of a series of processes executed by U21 in the convergence control will be briefly described with reference to FIGS. This flowchart is based on the convergence control unit 8.
1 and the target convergence current I set by the release judgment unit 82
This is the processing until dh * is output to the adder 84.

In S101, the vehicle speed V detected from the vehicle speed sensor is calculated, and in S102, the steering angle sensor 1
The steering angle is obtained based on the detection signal of No. 7, phase compensation is performed according to the steering angular velocity S, and the obtained steering angle is set to θ (processing of the phase compensator 35).

In the next step S103, a target steering angle θ * is obtained based on the vehicle speed V and the steering angle θ (processing of the target steering angle setting section 86). Next, in S104, a steering angle deviation Δθ (= θ * −θ) between the target steering angle θ * obtained in S103 and the steering angle θ obtained in S102 is calculated (processing of the subtractor 90).
Then, in S105, the target steering angular velocity Q * is calculated based on the vehicle speed V and the steering angle deviation Δθ (processing of the target steering angular velocity setting unit 87).

In S106, a steering angular velocity deviation ΔQ (= Q * -Q) between the target steering angular velocity Q * and the steering angular velocity Q is obtained (processing of the subtractor 91). And S107 to S112
Sets the target convergence current Ihd *. Note that this S1
Steps 07 to S112 correspond to the processing of the target convergence current setting unit 88.

In S107, P control is performed based on the steering angular velocity deviation ΔQ and the vehicle speed V, and the first convergence current Ihd1 * by the P control is calculated (processing of the first convergence current setting unit 96).

In S108, ΔQ × t is added to the integrated value of the steering angular velocity deviation ΔQ (ie, the steering angular velocity deviation integrated value) sum_ΔQ in the previous control cycle, and the sum is added as the steering angular velocity deviation integrated value sum_ΔQ in the current control cycle. Update. That is, integration processing is performed (processing of the integrator 99). Note that t is a calculation cycle (that is, a control cycle of this control flow).

In S109, I control is performed based on the integrated steering angular velocity deviation sum_ΔQ and the vehicle speed V in the current control cycle obtained in S108, and a second convergence current Ihd2 * by I control is calculated (second convergence current Ihd2 *). Processing of the setting unit 97).

In S110, the differential value of the steering angular velocity deviation ΔQ (that is, the differential value of the steering angular velocity deviation) d_ΔQ = (ΔQ-pr
e_ΔQ) / t is calculated. Note that ΔQ is a value in the current control cycle, and pre_ΔQ is a value in the previous control cycle.

Then, ΔQ in the current control cycle is updated as pre_ΔQ in the previous control cycle (differentiator 1
00). Then, in S111, the D control is performed based on the steering angular velocity deviation differential value d_ΔQ and the vehicle speed V, and the third convergence current Ihd3 * by the D control is calculated (process of the third convergence current setting unit 98).

The target convergence current Ihd * (= Ihd1 * + Ihd2 * + Ihd) obtained by combining the PID control in S112.
3 *) (process of the adder 101). In S113, a release judgment is performed based on the steering torque Th, and a gain (that is, a value of “0” or “1”) η is calculated (processing of the release judgment unit 82). At this time, if it is determined that the hand is released, the gain η is set to “1”. Otherwise (that is, if the steering is held or steered), the gain η is set to “0”.

In S114, it is determined that the steering / steering is being performed, that is, when the operation of the convergence control is prohibited (gain η = 0,
When the integral term used in the I control in step S115 (that is, the integrated steering angular velocity deviation sum_ΔQ in the current control cycle updated in step S108) is cleared to 0 and the convergence control is enabled again in step S115. To prevent malfunction due to the integral term.

In step S116, the target convergence current I obtained in step S112 is calculated using the gain η (= “1”) obtained in the release judgment.
hd * is corrected to obtain the final target convergence current Ihd *. That is, during steering / steering, the target convergence current Ihd * is corrected to 0, and the convergence control is prohibited. In the case of letting go, convergence control is performed.

As shown in FIG. 2, adder 84 calculates the result of the multiplication from multiplier 83 (ie, the output signal of target convergence current Ihd * or “0”) and the assist current from current command value calculator 31. The command value I is input, added, and the motor current command value Io is output to the subtractor 33.

Here, when the steering wheel 1 is being steered or steered and a predetermined steering torque Th is detected, the release signal determining unit 82 outputs an output signal of “0”. For this reason, the adder 84 outputs MA
-The assist current command value I of the MT control is output to the subtractor 33 as the motor current command value Io.

On the other hand, when the steering wheel 1 is lightly touched or released,
The steering torque Th is not input to the current command value calculation unit 31, and even if it is input, it becomes a very small value. Therefore, M
The assist current command value I of the A-MT control is not input to the adder 84. Even if it is input, it is a small value. Therefore, at this time, the target convergence current Ihd * is added to the assist current command value I, and the result is output to the subtracter 33 as the motor current command value Io.

Thereafter, the CPU 21 outputs the current to the CPU 21 via the subtractor 33 and the current controller 34 based on the motor current command value Io.
Drives and controls the motor 6. Therefore, even if the steering wheel 1 is released while being steered by a certain steering angle during traveling, an appropriate assisting force of the motor 6 can be obtained from the high speed to the low speed by the convergence control.

Therefore, according to the above embodiment, the following effects can be obtained. (1) In the above embodiment, when the steering wheel 1 is lightly touched or released, the effect is received by the assist current command value I based on the MA-MT control, but is not affected by the steering torque Th. The target convergence current Ihd * based on the convergence control is added to the assist current command value I, and the drive of the motor 6 is controlled by the motor current command value Io.

Therefore, unlike the related art, even if the vehicle is released at a low speed, the steering wheel 1 does not stop during the movement due to internal friction in the electric power steering device, and reaches the target steering angle θ *, which is a substantially neutral position. The steering wheel 1 can be returned well.

On the other hand, even at high speeds, the target convergence current Ihd * is added to the assist current command value I, and the drive of the motor 6 is reliably controlled. In such a case, the steering wheel 1 can provide stable convergence without overshooting.

(2) In the above embodiment, the target convergence current I
The determination as to whether or not hd * is to be added to the assist current command value I is made based on the magnitude of the steering torque Th detected by the release determination unit 82. For this reason, the release judgment unit 8
2, the target convergence current Ihd * is unnecessarily added when the release of the hand is not determined, that is, the value is sufficient to control the drive of the motor 6 with only the assist current command value I during the turning steering. It will not be done. As a result, the assist torque by the motor 6 decreases, and the steering of the steering wheel 1 does not feel heavy.

On the other hand, the target convergence current Ihd * can be reliably added when the steering wheel 1 is lightly touched or when the release is determined by the release determination unit 82 in the release state. The steering wheel 1 can be returned to the neutral position at a predetermined steering angular velocity Q.

(3) In the above embodiment, in the convergence control, the target convergence current Ihd * is set by the target convergence current setting unit 88.
Is set, the second convergence current Ihd2 * calculated by the I control is changed to the first convergence current Ih set by the P control.
Add to d1 *. Therefore, in the release state, there is no offset between the target steering angular velocity Q * for returning the steering wheel 1 to the substantially neutral position and the actual steering angular velocity Q of the steering wheel 1 without fail.
The actual steering angular velocity Q can be made to converge on Q * set by the target steering angular velocity setting section 87.

(4) In the above embodiment, in the convergence control, the target convergence current Ihd * is set by the target convergence current setting unit 88.
Is set, the third convergence current Ihd3 * calculated by the D control is replaced by the first convergence current Ih set by the P control.
Add to d1 *. Therefore, in the released state, the target steering angular speed Q * for returning the steering wheel 1 to the substantially neutral position does not delay the response to the actual steering angular speed Q of the steering wheel 1, and the actual steering angular speed Q Followability when converging to the target steering angular velocity Q * can be improved.

(5) In the above embodiment, the first and second convergence currents Ihd1 * and Ihd2 *, Ihd2 * and Ihd set by the I and D controls are added to the first convergence current Ihd1 * set by the P control.
hd3 * is added. Therefore, the target convergence current Ihd * having the effects (3) and (4) of the embodiment described above.
Can be set.

(6) In the above embodiment, when the motor 6 is driven based on the convergence control during the low-speed running, the target steering absolute angle setting section 93 of the target steering angle setting section 86 sets the target steering angle. The steering angle θ * is controlled so as to have a certain residual angle. Therefore, the rotation operation of the steering wheel 1 does not become unnatural as compared with the hydraulic power steering device.

Note that each of the above embodiments may be changed to another example as described below. In the above embodiment, in the convergence control, the convergence control unit 8
Although the target convergence current setting unit 88 sets the target convergence current Ihd * obtained by combining the so-called PID control, at least only the P control is executed, and the I control or the D control may not be executed. That is, when the D control is not performed, the target convergence current Ihd * is set to the first convergence current Ihd1 * set by the P control and the second convergence current Ihd set by the I control.
hd2 * is added and set. Even in this case, the same effect as (3) of the above embodiment can be obtained.

When the I control is not executed, the target convergence current Ihd * is set to the first convergence current Ihd1 * set by the P control and the third convergence current Ih set by the D control.
Set by adding d3 *. Even in this case, the same effect as (4) of the above embodiment can be obtained.

In the above embodiment, in the control device of the rack assist type electric power steering device, the MA
Although -MT control is performed, it may be embodied as a control device for a column and pinion assist type electric power steering device as shown in FIG.

In the figure, a speed reducer 5 is fixed to the steering shaft 2. A gear 7 attached to a rotation shaft of a motor 6 is engaged with the speed reducer 5. Further, a pinion shaft 8 is fixed to the speed reducer 5. The other configuration has the same configuration as that of the first embodiment, and thus the detailed description is omitted.

Further, in this embodiment, the same configuration as the electrical configuration of the first embodiment is employed, and only the method of determining assist current command value I is different from that of the first embodiment. How to determine the value I will be described below.

In the case of the column and pinion assist type, the rack thrust F at the time of the steering torque Th and the motor current Im is obtained by the following equation (E). F (Th, Im) = 2π (Th + K
t · Im · G · ηg) · ηp / St (E) where Th
Is steering torque, ηp is rack and pinion gear efficiency, St
Is the stroke ratio. Kt is the torque constant, G
Is the reduction ratio of the speed reducer 5, and ηg is the speed reduction efficiency of the speed reducer 5.

Therefore, using the above (E), the target steering torque Th * at the vehicle speed V, the steering angle θ, and the rack thrust F at the assist current command value I (hereinafter, this thrust is referred to as F (T
h *, I). ) And the rack thrust F at the time of the steering torque Th and the motor current Im (hereinafter, this thrust is referred to as F (T
h, Im). ) Are set equal to each other.

When F (Th *, I) = F (Th, Im),
When I is obtained by substituting the above equation (E), the following equation is obtained. I = Im + (Th−Th *) / (Kt · G · ηg) The assist current command value I thus obtained is output to the subtractor 33.

When the assist current command value I has the opposite sign to the target steering torque Th *, that is, reverse assist, the assist current command value I is determined to be zero and output to the subtractor 33. Thereafter, processing is performed in the same manner as in the first embodiment.

The target steering absolute angle setting map of the target steering absolute angle setting section 93 in the above embodiment may be controlled so as to be corrected in accordance with the road surface μ (dynamic friction coefficient of the road surface).
That is, in a region where the road surface μ (dynamic friction coefficient of the road surface) is low, the map is corrected as needed so that the target steering angle θ * set by the target steering angle setting unit 86 becomes large.

Further, the target steering angular velocity setting map of the target steering angular velocity setting section 87 in the above embodiment may be controlled so as to be corrected in accordance with the road surface μ (dynamic friction coefficient of the road surface). That is, in a region where the road surface μ (dynamic friction coefficient of the road surface) is low, the map is corrected as needed so that the target steering angular velocity decreases Q *.

In this way, the target steering angle θ * or the target steering angular velocity Q * is set according to the road surface μ (the coefficient of dynamic friction of the road surface), and the rotation of the steering wheel 1 is compared with the hydraulic power steering system. Operation does not become unnatural. Further, only the change in the friction in the electric power steering apparatus can be imparted with the unbiasedness regarding the convergence of the steering wheel 1.

In the above embodiment, in the convergence control,
At low speed, the target steering angle θ * is controlled by the target steering absolute angle setting unit 93 so as to have a certain residual angle.
The PU 21 may not be provided with the function of the target steering absolute angle setting unit 93, and may be controlled so that the steering wheel 1 is returned to the neutral position regardless of whether the speed is high or low.

In the above embodiment, the CPU 21 has the function of the hand-off determination section 82 for determining whether or not to add the target convergence current Ihd * to the assist current command value I.
The function of the hand release determination unit 82 may not be provided. Even in this case, it is possible to assist the steering wheel 1 in both the hand release state and the steering holding state.

In the above embodiment, the release judgment unit 82 outputs “0” or “1” as the gain η. However, when the release is not detected, the gain η is replaced with “0” instead of “0”. A value of 0 <η <1 may be output. In this way, unlike the first embodiment, instead of prohibiting the output of the convergence current, the convergence current can be output as a somewhat suppressed value.

[0131]

As described above in detail, according to the first aspect of the present invention, when the steering torque is not detected or is small,
Even if the assist current command value is not a sufficient value, the motor current command value is set by adding a target convergence current that is not based on the steering torque. Therefore, in the MA-MT control, unlike the related art, the steering wheel return characteristics can be improved during low-speed running, and the steering wheel convergence can be improved during high-speed running.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, since the release determination means determines whether or not to enable the output of the target convergence current, the assist current command Only when the value is insufficient, the target convergence current is reliably output.

According to the invention of claim 3, in addition to the effect of the invention of claim 1 or 2, the second convergence current calculated based on the integral value of the deviation between the target steering angular velocity and the steering angular velocity is: By being added to the first convergence current, there is no offset between the target steering angular velocity for returning to the neutral position and the actual angular velocity of the steering wheel, and the target steering angular velocity set by the target steering angular velocity setting means is assured. The actual steering angular velocity can be made to converge to the steering angular velocity.

According to the invention of claim 4, in addition to the effect of the invention of claim 1 or 2, the third convergence current calculated based on the differential value of the deviation between the target steering angular velocity and the steering angular velocity is: When the actual steering angular velocity converges to the target steering angular velocity without being delayed in response to the actual steering angular velocity, the target steering angular velocity for returning to the neutral position is added to the first convergence current. Performance can be improved.

According to the fifth aspect of the present invention, in addition to the effects of the first or second aspect of the invention, the effects of the third and fourth aspects can both be achieved. According to the invention of claim 6, in addition to the effect of the invention of any one of claims 1 to 5, at the time of low vehicle speed, the steering wheel is returned within the range of the residual angle, There is no unnaturalness compared to a hydraulic power steering device.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a control device of an electric power steering device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of the control device.

FIG. 3 is a flowchart of a target steering torque setting routine.

FIG. 4 is a functional block diagram of the phase compensator 35.

FIG. 5 is an explanatory diagram of a target steering torque setting map.

FIG. 6 is an explanatory diagram of a dead zone.

FIG. 7 is a block diagram of a current command value calculator.

FIG. 8 is an explanatory view of calculating a dead zone width.

FIG. 9 is a block diagram of a convergence control unit.

FIG. 10 is a block diagram of a target steering angle setting unit.

FIG. 11 is a flowchart of a target steering angle calculation routine.

FIG. 12 is a flowchart of convergence control.

FIG. 13 is a flowchart of convergence control.

FIG. 14 is an explanatory diagram of a hand release determination.

FIG. 15 is a schematic diagram of a control device according to an electric power steering device of another embodiment.

FIG. 16 is a schematic diagram of a control device according to a conventional electric power steering device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steering wheel (handle), 6 ... Motor, 21 ... CPU (Control means, target steering torque setting means, assist current calculating means, target steering angle setting means, target steering angular velocity setting means, target convergence current setting means, release judgment Means: 31: current command value calculation unit (assist current calculation means); 32: target steering torque setting unit (target steering torque setting means); 81: convergence control unit (target steering angle setting means, target steering angular velocity setting means) Target convergence current setting means) 86: target steering angle setting section (target steering angle setting means) 87: target steering angular velocity setting section (target steering angular velocity setting means) 88: target convergence current setting section (target convergence current setting means) , 82... A release determination unit (release determination means).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) B62D 113: 00 B62D 113: 00 117: 00 117: 00 119: 00 119: 00

Claims (6)

[Claims] 1. A control device for an electric power steering device comprising a control means for controlling a drive of a motor based on a motor current command value, wherein a target steering torque setting means for setting a target steering torque based on a steering angle and a vehicle speed; An assist current calculating means for calculating an assist current command value based on a steering torque, the target steering torque, and a motor current of the motor; and a target steering angle for returning the steering wheel to a neutral position based on the steering angle and the vehicle speed. Target steering angle setting means for setting a target steering angle speed based on a deviation between the target steering angle and the steering angle and a vehicle speed, and a target based on a deviation between the target steering angular velocity and the steering angular velocity. And a target convergence current setting means for setting a convergence current. A control device for an electric power steering device, wherein a motor current command value is added to a command value. 2. A release control means for performing release determination of a steering wheel based on a steering torque, based on a determination result of the release determination means, enabling or suppressing output of a target convergence current of a target convergence current setting means. The control device for an electric power steering apparatus according to claim 1, wherein the motor current command value is added to the assist current command value. 3. The target convergence current setting means calculates a first convergence current proportional to a deviation between the target steering angular velocity and the steering angular velocity, and further calculates a second convergence current based on an integral value of the deviation between the target steering angular velocity and the steering angular velocity. 3. The control device for an electric power steering device according to claim 1, wherein a target convergence current is set by calculating the two convergence currents. 4. 4. A target convergence current setting means calculates a first convergence current proportional to a deviation between the target steering angular velocity and the steering angular velocity, and further calculates a third convergence current based on a differential value of the deviation between the target steering angular velocity and the steering angular velocity. 3. The control device for an electric power steering device according to claim 1, wherein a target convergence current is set by calculating the two convergence currents. 4. 5. A target convergence current setting means calculates a first convergence current proportional to a deviation between the target steering angular velocity and the steering angular velocity, and generates a second convergence current based on an integral value of the deviation between the target steering angular velocity and the steering angular velocity. And calculating a third convergence current based on a differential value of a deviation between the target steering angular velocity and the steering angular velocity, and adding the convergence currents to set a target convergence current. Item 3. A control device for an electric power steering device according to item 2. 6. The neutral position includes a predetermined residual angle range, and the target steering angle setting means, when the vehicle speed is low,
The control device for an electric power steering device according to any one of claims 1 to 5, wherein the target steering angle is set so that the steering wheel is returned within the range of the residual angle.