JP2910403B2 - Electric 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 an electric power steering control device capable of generating an auxiliary steering force in accordance with a steering force of a steering and obtaining a smooth and constant steering torque without a sense of discomfort. .

[0002]

2. Description of the Related Art In a conventional electric power steering control device, for example, as shown in Japanese Patent Application No. 63-287008, basic auxiliary steering determined based on a steering torque applied during steering and a target control torque. Conventionally, a motor control amount is obtained by adding a correction amount obtained from a differential value of an error amount between a target control torque and a steering torque to a force.

[0003]

However, since the control amount obtained by adding the correction amount obtained from the differential value of the error amount to the basic auxiliary steering force as described above does not have an integral component, a steady-state error occurs and the target control torque is increased. Therefore, there is a problem that fine-grained target steering torque characteristics cannot be realized, responsiveness is limited, and micro vibration of the steering is caused.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an electric power steering control device capable of realizing good responsiveness and stable steering feeling. .

[0005]

An electric power steering control device according to the present invention includes means for calculating a proportional value, an integral value, and a differential value of a deviation between a detected steering torque and a target steering torque, and a method for setting a lower limit value of the integral value to 0. A first clipping means for clipping at the above predetermined lower limit value , and a control value obtained by adding the proportional value, the integral value and the derivative value between the upper limit value and the lower limit value of the motor command voltage or command current value. And a second clip means for clipping.

[0006]

In the present invention, when the detected steering torque is less than the target steering torque, the integrated value of the deviation is equal to or greater than zero.
Clipped to the lower limit,
The motor control value becomes the minimum value, the motor is not assisted at all, and the rising operation when the steering detection torque exceeds the target steering torque is accelerated. In addition, the presence of the integration means eliminates a steady-state deviation.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a basic configuration of the electric power steering control device according to this embodiment, 1 is a steering wheel, 2 is a steering torque detecting means, and an output according to the steering force of the steering wheel 1 is obtained. Reference numeral 3 denotes a motor, which is connected to a steering shaft 5 via a speed reducer 4. A control unit 6 calculates a control amount from the output of the steering torque detecting means 2 and controls the motor 3 according to the control amount. 7 is a wheel.

FIG. 1 shows the configuration of the control unit 6, wherein 10 is a steering torque phase advance compensating means, 11 is a target steering torque setting means, 12 is a proportional means, 13 is an integrating means, 14 is a differentiating means, and 15 is a motor drive. Means, 16 is a subtraction means, 17 is an addition means, and 18, 19 are first and second clip means.

Next, the operation of the above configuration will be described. When the steering wheel 1 is steered and torque is applied to the steering shaft 5, a detection signal T _m is output from the steering torque detecting means 2.
Is output. Phase lead compensating means 10 is intended to compensate for the delay due to inertia and friction of the motor 3 and the reduction gear 4, a steering torque after compensation to T _s. Subtraction means 16 calculates the deviation T _h = T _s -T _r a target steering torque as T _r,
Proportional value P _n by the means 12 to 14 and the deviation T _h based on the integral value I _n, calculates a differential value D _n. That is, _{P n = K p × T h} I n = K I × T h + I n-1 D n = K D × (T h (n) -T h (n-1)). Here, K _p , K _I , and K _D are proportional, integral, and derivative coefficients, respectively, and n−1 indicates a calculated value one operation cycle before. Also, I _n performs a clip to the upper and lower limit by the first clip means 18. The lower limit is the lower limit of the control value of the motor 3, that is, the lower limit of the duty command value of the PWM control, for example, 0, and the upper limit is 250. Next, the adding means 17
The P _n, I _n, by adding the D _n, the control value T of the motor 3
_Ask for _e . That is, T _e = P _n + I _n + D _n . T
_{e is} also clipped to the upper and lower limits by the clipping means 19.
For example, the upper limit value is the maximum value 250 of the PWM of the motor command value.
And the lower limit value is also the minimum value 0. This control value T
_e to the motor driving means 15 so that the motor 3
Generates an optimal auxiliary steering force, which is applied to the steering shaft 5 via the speed reducer 4.

The motor driving means 15 is disclosed in Japanese Patent Application
FIG. 3 shows an H-bridge circuit disclosed in US Pat. No. -246191. 21-24 is a transistor, the transistor 21 and 22 to the control value T _e and PWM duty ratio, the duty of 100% power at the maximum value 250 of the T _e, so as not to drive the motor 3 at the minimum value 0 I do.

[0011] Thus, the integrated value I _n the steering torque signal T _s is less than the target steering torque T _r is 0 when it should become negative, the control value T _e is also 0, the motor 3 is not at all assisted, T As soon as _s exceeds _Tr , the assist of the motor 3 is started, and the control delay at the start of the assist when the steering wheel 1 is cut from a small torque can be eliminated. Further, since the integrator 13 is provided, the target steering torque _Tr can be accurately controlled without a steady-state deviation, and the target steering torque characteristic can be ideally realized without delay.

In the above embodiment, the calculation is performed digitally, but the calculation may be performed analogly. Further, the control amount of the motor 3 is set to the applied voltage (PWM command value). It may be a command value of a minor loop of current feedback.

[0013]

As described above, according to the present invention, when the steering torque is equal to or less than the target steering torque , the integral term of the deviation is obtained.
Is clipped to a predetermined lower limit of 0 or more and becomes negative.
In addition, since the motor control amount becomes the minimum value, the motor is not assisted at all, and when the steering torque exceeds the target value, the assist control is immediately started to improve the responsiveness. In addition, since the integration means is provided, the steady-state deviation is eliminated, and the upper limit value is provided for the motor control amount, so that the convergence to the target value can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control unit of the device of the present invention.

FIG. 2 is a configuration diagram of the device of the present invention.

FIG. 3 is a configuration diagram of a motor driving unit according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering torque detecting means 3 Motor 5 Steering shaft 6 Control part 10 Phase advance compensating means 11 Target steering torque setting means 12 Proportional means 13 Integrating means 14 Differentiating means 15 Motor driving means 16 Subtracting means 17 Adding means 18, 19 Clip means

Continuation of the front page (72) Inventor Masanori Takagi 840 Chiyoda-cho, Himeji-shi, Hyogo Mitsubishi Electric Corporation Himeji Works (56) References JP-A-4-71959 (JP, A) JP-A-3-3004 ( JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B62D 6/00 B62D 5/04

Claims (1)

(57) [Claims] 1. Means for detecting a steering torque of a steering, means for obtaining a deviation between the detected steering torque and a target steering torque, means for obtaining a proportional value, an integral value and a differential value of the deviation, and an auxiliary steering torque for the steering And the lower limit clip value of the integral value is set to a predetermined lower limit of 0 or more.
A first clipping means for setting a value, and a second clipping means for clipping a control value obtained by adding the proportional value, the integral value and the differential value between the upper limit value and the lower limit value of the motor command voltage or command current value. An electric power steering control device, comprising: a clipping means; and means for controlling a motor based on the control value.