JP3248297B2 - Power steering control device - Google Patents

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 a power steering device (power steering device) for controlling an assist torque.

[0002]

2. Description of the Related Art Conventionally, a device for controlling the assist torque of a power steering by hydraulic pressure has been used.
A device for generating the hydraulic pressure by an electric pump has been proposed. This electric pump type has an advantage that the rotation of the pump can be freely controlled. Under the control of this system, the drive voltage of the motor of the electric pump is always detected by feedback, and PI
There has been proposed a system in which control is performed to follow a target voltage applied to a motor by (proportional integration) control.

[0003]

However, in the control using the above PI control, if the control is set to increase the following speed when the control alone follows the target value,
That is, in order to increase the response, the control value acts to cause overshoot as is well known in control theory. Therefore, if the controlled object changes frequently, the control value cannot catch up, and there is a problem that the control accuracy is reduced. In the control of this system, the response cannot be sacrificed due to the nature of the assist torque, so that the following speed cannot be increased as it is, and there is a problem that only a certain control accuracy can be obtained.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a structure of the present invention is a control apparatus for a power steering apparatus for controlling a motor voltage applied to a motor for controlling an assist torque. Voltage setting means for setting a voltage value, and voltage correction means, the voltage correction means is a deviation detection means for detecting a voltage deviation between the target voltage value and the motor voltage, multiplying the voltage deviation by a coefficient Voltage following speed setting means for obtaining a voltage following speed, deviation speed setting means for detecting the deviation speed of the voltage deviation, voltage following speed correcting means for largely correcting the voltage following speed when the deviation speed is positive, the voltage following An adder for adding a correction voltage value obtained based on the voltage following speed corrected by the speed corrector to the target voltage value and outputting the corrected voltage value.

[0005]

The target voltage value is set by the voltage setting means, and a desired correction amount is obtained based on the voltage deviation between the target voltage and the motor voltage according to the value. For the correction, first, a voltage following speed amount proportional to the voltage deviation is obtained from the voltage deviation. At the same time, the change in the voltage deviation is checked to determine the deviation speed. When the speed is positive, that is, when the deviation is large, the correction is increased, and when the deviation is small, the voltage following speed is corrected so as to reduce the correction. A corrected voltage value is obtained based on the corrected voltage following speed amount, converted into a driver drive signal, and output to the motor driver together with the target voltage value.

[0006]

When the voltage deviation is large, it means that the follow-up value to the motor voltage overshoots, and the actual applied voltage is gradually deviating from the target value. The correction amount obtained at this time has an amount such that the motor voltage value approaches the original target voltage value, and the following speed correction is performed in a form in which the motor voltage value is strengthened, so that the overshoot is largely suppressed. That is, the signal oscillation is suppressed to converge quickly, that is, the followability is improved, and as a result, the control accuracy is improved.

[0007]

【Example】

(First Embodiment) Hereinafter, the present invention will be described based on specific embodiments. FIG. 1 is a configuration diagram showing a configuration of an electric pump type power steering device according to the present invention. Reference numeral 30 denotes a vehicle speed sensor for detecting the vehicle speed of the automobile, 31 denotes a control device, and the control device 31 receives an output signal from the vehicle speed sensor 30 and is connected to the driver 20. Electric power is supplied from the battery B to the motor 21 by a signal. Further, P is a pump rotated by the motor 21, and an electric pump is constituted by the pump P provided integrally with the motor 21, and the working fluid sent from the pump P is supplied to the servo valve 32. . Furthermore, the load current flowing through the motor 21 is
Detected by 3, actually (referred to hereafter as the motor voltage V _M) applied voltage to the motor 21 is detected by the voltage detector 34, whose output signal is input to the control unit 31. Reference numeral 35 denotes a gear housing constituted by a rack and pinion gear. Reference numeral 36 denotes a power cylinder for generating an auxiliary steering force. As described above, the supply and discharge of working fluid to and from the power cylinder 36 are controlled by the servo valve 32, and the left and right steering rods 40 of the piston 39 of the power cylinder 36 are provided. To operate the ball joint 41 to rotate a steering wheel (not shown).

FIG. 2 is a block diagram showing the control of the electric pump section of the present invention.
The inside of the frame 2 constitutes the voltage correcting means. The voltage setting means 1 compares the target voltage a section 11 and the target voltage b section 12 with each other, whichever is greater, to provide a target voltage value V ₀ , and a basic value for the driver 20 from the target voltage value V _0. It comprises a basic value setting unit 13 for giving C _B.
Voltage correcting means 2, to obtain a voltage deviation V _E between the target voltage value V ₀ and the motor voltage V _M, the voltage follower speed calculator 14 for obtaining the value [Delta] V _A proportional as the voltage tracking speed based on this value,
And tracking speed correction calculation unit 15 for obtaining the correction value [Delta] V _B of the original voltage follow-up speed change rate of the voltage deviation in parallel to the voltage follower speed calculator 14, a motor voltage fluctuations to determine the rate of change [Delta] V _M of the motor voltage An arithmetic unit 16 is provided, which comprises a correction accumulation arithmetic unit 17 for integrating these arithmetic results to obtain a total correction amount ∫Eu. A motor driver 20 is connected to the motor 21 to be controlled.

The control of this embodiment is performed by a CP (not shown).
The arithmetic processing is performed in U. This is because the control of the entire power steering is also processed by the CPU, and here, a control block diagram of only the electric pump unit relating to the present invention is shown. The voltage applied to the motor is fed back to the CPU through the A / D converter 19 in order to be fed back. The CPU receives signals necessary for power steering operation, such as a signal from the vehicle speed sensor 30, a motor current value, and a motor voltage value. The control configuration of the electric pump unit is a proportional term in the basic value setting unit 13, and the conventional PI control is performed in parts other than the proportional term. Therefore, the PI control is performed as a whole.

The target voltage for the motor 21 of the electric pump to be controlled is first set to the target voltage a section 11, which depends on the vehicle speed.
The motor current-dependent target voltage b section 12 is controlled by the CPU based on signals from the vehicle speed sensor 30 and the motor current detector 33, respectively.
The target set voltage value V _{0 of the} motor, which is determined by the larger value of the target voltage a or the target voltage b, is calculated. The V ₀ again by calculating a basic value setting unit 13 for the driver drive output in CPU, and calculates a basic set value C _B to the driver 20. A / D converter 1
Voltage deviation V _E of the motor voltage V _M and the target value taken from 9 (= V ₀ -V _M) is calculated, and the voltage up speed 14
To obtain the voltage following speed ΔV _A. At the same time, a correction value ΔV _B of the voltage following speed is calculated and added to ΔV _A to obtain ΔV _C. In the case of this embodiment, the change rate of the difference of the voltage deviation is checked by the deviation varying unit 23, and the switch S is turned on only when the magnitude of the voltage deviation increases, and the switch is added when the magnitude of the voltage deviation decreases. No correction is made with S off (ΔV _B = 0). Next, the differential value ΔV _M of the motor voltage is subtracted from ΔV _C to calculate a speed deviation Eu, which is accumulated, a correction voltage value ΔEu is calculated, and the calculation result ΔEu is used as a driver drive output correction setting unit. 18 into a voltage correction value signal ΔC by and sent to the driver 20 by adding the previous basic setting value C _B. Here, since a driver that controls a motor voltage by switching a DC power supply is used as the driver 20, the driver 20 is not configured to directly apply a specified voltage to the motor. Therefore, the command voltage value C is output in a form such as a PWM (pulse width modulation) method. This is because the pulse processing section 18 after the correction accumulation operation section (integral term) 17 uses a driver 20 driven by the signal. Note that the target voltage b is provided for continuous energization without on / off control because the PWM method generates a large amount of heat in a region where the motor current is large.

Since this control is performed by software, a configuration routine of the control calculation is shown in a flowchart of FIG. Step 200 A vehicle speed sensor, calculates a target voltage V ₀ from the motor current value. By feeding back the voltage applied to the motor at step 202 is a proportional term calculated voltage deviation V _E between the target voltage voltage tracking rate amount ΔV
Calculate _A. Step 204 obtains a rate of change of the voltage difference V _E in, it is determined whether the absolute value becomes larger. If it becomes larger, a predetermined correction value ΔV _B is given in step 206, and if it becomes smaller, step 208
And ΔV _B = 0 (corresponding to the switch S). Then, in step 210, ΔV _B is added to ΔV _A to obtain ΔVc.
A deviation Eu (= ΔVc -ΔV _M) with [Delta] Vc to calculate the differential value [Delta] V _M of the motor voltage V _M at step 212,
Output to the integral term 17. As a result, the correction value ΔC is pulsed in step 214. Then calculate the basic value C _B of the output from the target voltage V ₀ at step 216, step 21
8 and ΔC from the integral term 17 and the final indicated voltage value C =
And outputs the C _B + [Delta] C to the driver 20.

With this correction, it is possible to apply a voltage having a good follow-up property to the motor, and it is possible to maintain the rotation speed of the pump as desired and to maintain a necessary pump flow rate. Fig. 4
Is schematically shown in the form of a target voltage. In the conventional characteristics, the response is oscillatory, but follows the target voltage V ₀ in such a manner as to cancel the overshoot by the effect of the present invention.

(Second Embodiment) FIG. 5 is a block diagram of a second embodiment of the present invention, in which the present invention is applied to a conventional PI control in which the basic value setting unit 13 is removed as compared with FIG. It is. A part for performing the following speed correction in parallel with the voltage following speed calculation unit 14 for converting the proportional coefficient of the voltage deviation between the target voltage value and the feedback voltage is added (15 in FIG. 5). However, this component is set to be turned on only when the change V _E of the voltage deviation is increased by the switch S.

The effect of the present invention is the same as that of the first embodiment in the feedback control of the second embodiment without the basic value setting unit 13 of the first embodiment.
5 reduces the overshoot of the follow-up value, the convergence becomes faster by that amount, and the target voltage is accurately reflected.

The following speed correction 15 characterizing the present invention
Is a block diagram described by one element of the voltage following speed 14 as shown in FIG. 6 as shown from the control theory. In other words, this means that the characteristic of the voltage following speed calculation unit 14 is changed from the linear conversion characteristic to the hysteresis characteristic instead of adding the element of the following speed correction 15, and this characteristic is a reason for improving the followability. I can say. Therefore, the present invention provides various characteristics to the voltage following speed calculation unit 14 according to the purpose, thereby enabling an optimum pump flow rate control to be performed according to the purpose of the apparatus in addition to the above embodiment. There is. Although the above embodiment has described the electric pump type power steering device, the present invention is also applicable to an electric power steering device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an electric pump type power steering device according to the present invention.

FIG. 2 is a block diagram showing the configuration of the first embodiment of the present invention.

FIG. 3 is a flowchart of the first embodiment.

FIG. 4 is a characteristic diagram with respect to a target voltage value of the first embodiment.

FIG. 5 is a block diagram showing a configuration of a second embodiment.

FIG. 6 is a block diagram showing a configuration of an integrated voltage tracking speed calculation unit.

[Explanation of symbols]

Reference Signs List 1 voltage setting means 2 voltage correction means 13 basic value setting unit 14 voltage tracking speed calculation unit (voltage tracking speed setting means) 15 tracking speed correction calculation unit (deviation speed setting means, voltage tracking speed correction means) 16 motor voltage fluctuation calculation unit 17 Correction accumulation operation unit (integral term) 20 Motor driver 21 Motor 22 Battery 30 Vehicle speed sensor 32 Servo valve 35 Gear housing Step 200, 216 ... Voltage setting means Step 202 ... Deviation detection means, voltage following speed setting means Step 204 ... Judging section including deviation speed setting means Steps 204, 206, 208, 210, 212
Voltage correction means Steps 206, 208 ... Voltage tracking speed correction means, equivalent to switch S Step 218 ... Addition means

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-132470 (JP, A) JP-A-3-42376 (JP, A) JP-A 5-42878 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B62D 6/00 B62D 5/07

Claims (1)

(57) [Claims] 1. A control device for a power steering device for controlling a motor voltage applied to a motor for controlling an assist torque, comprising: voltage setting means for setting a target voltage value to be applied to the motor; and voltage correction means. The voltage correction means, a deviation detection means for detecting a voltage deviation between the target voltage value and the motor voltage, a voltage following speed setting means for multiplying the voltage deviation by a coefficient to obtain a voltage following speed, a deviation speed of the voltage deviation Speed setting means for detecting the voltage tracking speed, the voltage following speed correction means for largely correcting the voltage following speed when the deviation speed is positive, and the voltage following speed determined by the voltage following speed corrected by the voltage following speed correcting means. A control device for a power steering device, further comprising an adding means for adding a correction voltage value to the target voltage value and outputting the corrected voltage value.