JPH05224702A - Bang-bang controller - Google Patents

Abstract

PURPOSE:To ensure the identification at a high speed and with a reduced error for the constant of a motor to be actually controlled in its operation mode. CONSTITUTION:In regard of a motor 1, two manipulated variables are properly controlled by switching over at each time by two instruction signals received from a manipulated variable switch means 3. Then the rotational angle theta(t) of the driven motor 1 is detected and stored by a controlled variable storage means 5 which is connected to the motor 1. A dynamic characteristic parameter calculation means 6 is connected to the means 5 to calculate the ratio between the inertia and the coefficient of viscous friction and the ratio between the steady gain and the coefficient of viscous friction of the motor 1 respectively from the rotational angle and by the approximate calculation. Furthermore the output of the means 6 is inputted to a switching time calculation means 7 so that the switching time of the manipulated variables is calculated based on bath ratios calculated by the means 6. Then the calculated switching time is sent to the means 3 and the bang-bang control is attained for the motor 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bang-bang control device.

[0002]

2. Description of the Related Art Bang-bang control uses two manipulated variables, a positive maximum output and a negative maximum output, and continuously controls and changes an output switching time with respect to a controlled object.
It is one of the control methods that can reach the target value in the shortest time. In this control, there is no feedback element and the control method is a strong feedforward control method designed by the dynamic characteristic parameter of the controlled object and the target value. ..

When the bang-bang control is performed on the motor, the impulse response waveform or step response waveform of the motor to be used is analyzed in advance, and the characteristic amount such as the rise time or the settling time is extracted to extract the motor constant. Is identified and bang-bang control is performed based on that.

[0004]

However, in a control system with a strong feedforward element such as the above-mentioned bang-bang control, if there is an error in the identified motor constant, the greater the error, the greater the influence on the control performance. Then, during actual operation, the characteristics of the motor often change greatly compared to the previous control due to fluctuations in the load connected to the motor. Therefore, the bang-bang control cannot be performed accurately with the motor constants identified based on the various waveforms obtained last time or before.

Further, as described above, since the motor constants necessary for the bang-bang control have been conventionally identified by analyzing the above-mentioned various waveforms, the calculation processing is complicated and enormous, so that high-speed processing cannot be performed. It was

The present invention has been made in view of the above background, and an object of the present invention is to identify a parameter during operation of a control target to be actually controlled at a high speed and with a small error, thereby achieving high accuracy. It is to provide a bang-bang control device capable of performing the bang-bang control of the above.

[0007]

In order to achieve the above-mentioned object, in a bang-bang control device according to the present invention, a bang-bang control device for controlling a bang-bang control target whose parameters showing dynamic characteristics dynamically change is operated. A dynamic characteristic parameter calculation that detects a control amount at any of a plurality of points during a fixed amount of time, and calculates the parameter from the control amount storage unit that stores the control amount and the control amount of the plurality of points that the control amount storage unit stores And a switching time calculating means for calculating the operation amount switching time in the bang-bang control from the dynamic characteristic parameter calculated by the dynamic characteristic parameter calculating means.

[0008]

The control amount is detected at a plurality of points, for example, two points, when the operation amount is constant when the controlled object is actually operating (especially after the start and before the operation amount changes). Calculate the switching time. Then, the operation amount is switched based on the calculation result, and the bang-bang control is performed. The above process is performed every time the control is performed, that is, immediately after the control is started. Therefore, even if the characteristics greatly change from the previous one during the actual control due to load fluctuations or other reasons, the identification is performed based on the characteristics during the actual control, so that the identification error is small and highly accurate control is performed. ..

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a torque detecting device according to the present invention will be described in detail below with reference to the accompanying drawings. In this example, an example of a bang-bang control device for positioning the motor is shown. The configuration is such that the output of the motor 1 is transmitted to the load 2 as shown in FIG. A command signal from the quantity switching means 3 controls switching between two operation quantities (acceleration / deceleration with positive or negative maximum output) at appropriate times. That is, when moving in the positive direction, first, acceleration is performed at the maximum positive output, then deceleration is performed at the maximum negative output before the operation amount switching time, and when the target point is reached, the speed becomes zero and the moving body (load 2) is stopped at a predetermined position (the rotation angle of the motor 1 is stopped at a predetermined angle), the switching point is set, and the operation amount switching means 3 controls the rotation of the motor 1. Specifically, a current as shown in FIG. 2 is applied to the motor.

In the present invention, the control amount storage means 5 is first connected to the motor 1. This control amount storage means 5
Is capable of detecting the rotation angle θ (t) of the operating motor 1 and storing the detected value.

The output of the control amount storage means 5 is input to the dynamic characteristic parameter calculation means 6, where the inertia and viscosity of the motor 1 which are parameters are approximated from the above rotation angle. The ratio of the friction coefficient and the ratio of the steady gain and the viscous friction coefficient are calculated.

Further, the dynamic characteristic parameter calculating means 6
Is input to the switching time calculation means 7, and here, the operation amount switching time for performing the bang-bang control is calculated based on the both ratios. Then, the calculated result is sent to the manipulated variable switching means 3 to control the motor 1.

Next, the principle of operation and the specific operation of the apparatus having the above construction will be described. First, considering the design of the bang-bang control, the transfer function G (s) of the motor 1 is considered.
Is as follows.

G (s) = K / s ² (Js + D) (1) where K is a steady gain, J is the inertia of the motor, and D is
Indicates the viscous friction coefficient.

The step response θ '(t) at the motor rated current I is given by the following equation, where u (t) is the step function.

[0016]

## EQU1 ## θ '(t) = (KI / D) (t- (D / J) (1-exp (-(D / J) t))) u (t) (2) Further, The response θ (t) by bang-bang control is

[0017]

## EQU2 ## θ (t) = θ '(t) -2θ' (t-τ) + θ (t-T) (3) However, the relationship between the manipulated variable switching time τ and the manipulated variable switching point θp is θ (τ) = θp, and the control purpose is that the rotation angle (target point) at the control end time T is θr and the speed at that time is Zero, that is, θ (T) = θrd θ (T) / dt = 0. Then, bang-bang control is designed by setting θp and then τ that satisfy the above equation.

By the way, if A = KI / D B = D / J, then from the above equation (2)

[0019]

## EQU3 ## θ '(t) = B (t- (1 / A) (1-exp (-At))) (4), and the above A (the ratio between the steady gain and the viscous friction coefficient (however, I Is constant)) and B (ratio of inertia and viscous friction coefficient) as variables, and bang-bang control design can be easily performed by obtaining them. Therefore, the principle of calculating A and B (which is the parameter obtained by the dynamic characteristic parameter calculating means) is shown below.

That is, considering the response at the time of acceleration, from the above equation (3),

[0021]

## EQU00004 ## .theta. (T) = B (1- (1 / A) (1-exp (-At))) u (t) (5) is obtained.

Then, in the above equation (5), t1 and t2
(However, 0 <t1 <t2 <τ) is substituted to obtain θ
When the ratio of (t1) and θ (t2) is taken, B is erased and the following equation is obtained.

[0023]

[Equation 5] That is, since the above formula is a function of only A, this is set to f (A), and the ratio of the inertia to the viscous friction coefficient can be roughly determined by the type of the motor to be controlled and the actual load. Therefore, when this function f (A) is subjected to linear Taylor expansion with this value as A0,

[0024]

## EQU6 ## f (A) = f (A0) + (A-A0) f '(A0) However, f' (A) = df (A) / dA. Therefore, A is

[0025]

(7) A = A0 + (f (A) −f (A0)) / f ′ (A0) (6) Here, since f (A0) and f '(A0) can be calculated (measured) in advance, they can be regarded as constants. Therefore, by measuring f (A), a linear equation can be calculated. A is easily required.

At this time, B is

[0027]

Since B = θ (t1) / {t1− (1 / A) (1−exp (−At1)} (7), A obtained from the above expression (6) is added to this expression. By substituting, it is possible to calculate B. In this way, both parameters A and B are calculated by a simple formula, and based on this, τ and θp are calculated by the above formulas (2) and (3), You can perform various bang-bang control.

As a concrete operation, as shown in FIG. 2, the rotation angle is controlled at arbitrary plural points (two points (t1, t2 in this example)) immediately after the motor is started (before the operation amount switching time). It is detected and recorded by the quantity storage means 5. Then, based on the recorded rotation angles θ (t1) and θ (t2), the dynamic characteristic parameter calculating unit 6 uses the above equations (6) and (7) to calculate the ratio B between the inertia of the motor 1 and the viscous friction coefficient. , And the ratio A between the steady gain and the viscous friction coefficient is calculated and identified. Then, based on the calculation result, equations (2) and (3)
Thus, the operation amount switching time is calculated, the calculation result is output to the operation amount switching means 3, and the motor is bang-bang controlled.

The above-mentioned processing is carried out immediately after the start of each control. Therefore, even if the motor characteristics change significantly from the previous time during actual control due to load fluctuations and other reasons, identification is performed based on the characteristics of the motor that is actually controlling, so there are few identification errors and high accuracy. You can control. Moreover, as described above, since the identification process can be performed by a simple calculation process based on the two rotation angles, high-speed processing can be performed for online data measurement.

The two points t1 and t2 are empirically determined, and it is preferable to select two points before the expected switching time and before the time required for the calculation processing. Then, the interval between the two points is determined by the arithmetic processing of the system used. In addition, the actually measured t2 is the switching time τ calculated at A (A0) in the previous control.
If it is larger or closer, the previous A or the like is used without using the rotation angle θ (t2) based on t2. In addition, in the above-mentioned embodiment, the example for the bang-bang control for the motor is shown, but the present invention is not limited to this, and can be used for various control targets.

[0031]

As described above, in the bang-bang control device according to the present invention, the control amount of the controlled object at the time of actual control is detected, and the parameter is identified based on the detected control amount. High-precision bang-bang control can be performed with.

[Brief description of drawings]

FIG. 1 is a block diagram showing a preferred embodiment of a bang-bang control device according to the present invention.

FIG. 2 is a waveform diagram for explaining the operation of bang-bang control.

[Explanation of symbols]

 1 Motor (Control Target) 5 Control Quantity Storage Means 6 Dynamic Characteristic Parameter Calculating Means 7 Operation Quantity Switching Time Calculating Means

Claims (2)

[Claims] 1. A bang-bang control device for bang-bang control of a control object whose dynamic characteristic parameter dynamically changes. In a bang-bang control device, a control quantity is detected and stored at a plurality of arbitrary points during a fixed operation period. Amount storage means, a dynamic characteristic parameter calculation means for calculating the parameter from the control amounts of a plurality of points stored in the control amount storage means, and an operation amount in bang-bang control from the dynamic characteristic parameter calculated by the dynamic characteristic parameter calculation means. A bang-bang control device comprising a switching time calculating means for calculating a switching time. 2. The control target is a motor, the controlled variable is a rotation angle of the motor, and the parameter calculated from the rotation angle is a ratio of inertia and viscous friction coefficient of the motor, and a steady gain. The ratio of the viscous friction coefficient to the viscous friction coefficient according to claim 1.