JPH0285902A - Feedforward controller - Google Patents

Abstract

PURPOSE:To improve the operability at control of the equipments by performing the automatic learning and control of the velocity feedforward gain for execution of the feedforward control. CONSTITUTION:When the position command value X1 is received, a learning controller 14 changes sequentially the value of a gain varying device 13 by means of the position deviation (e) and the output of a differentiator 11, i.e., the velocity command value V so that the value (e) is converged to zero. In this case, the learning control rule of the velocity feedforward gain wi shows that the gain wi is automatically obtained by a method where the increment proportional to the product signal of the value V and the position deviation signal is sequentially added to the gain wi. Thus it is not required to set an optimum feedforward gain corresponding to the mechanical load in terms of the trial and error. As a result, the highly accurate feedforward control is attained with a small follow-up delay.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to a feedforward device that reduces tracking errors in a servo system that performs computer numerical control or trajectory control of robots, etc., and in particular automatically learns feedforward gain. The present invention relates to a feedforward control device that has a function of controlling and adjusting the feedforward control device.

[Prior art] Figure 5 is, for example, No. 176 of "Cutting-edge technology for machine tools" (edited by the Japan Society of Mechanical Engineers, Kogyo Kenkyukai, April 1988).
1 is a block diagram of a conventional feedforward control device shown in FIG. In the figure, (1) is a position command value X given from the outside, (2) is a device detection value Y consisting of a position detector (10) connected to a servo motor (9),
(3) is a subtracter which outputs a position deviation value e-X-Y between the position command value X and the position detection value Y. (4) is a position controller having a position loop gain K and an output signal K −
Output e.

p (5) is the adder, (6) is the speed command value F output from the adder (5), (7) is the speed and current control system, (8> is the power amplifier, and (9) is the servo The motor, (10) is a position detector, and (11) is a differentiator, which outputs a speed signal V.

(12) is a coefficient multiplier, and the multiplication coefficient is α.

The conventional feedforward control device is configured as described above, and the operation of the feedback control system that drives the servo motor (9) is based on the position detection value Y (2) relative to the given position command value X (1). Since feedback control is performed based on the deviation value e-X-Y, a steady speed deviation occurs.

As a result, a trajectory error occurs during two-axis driving such as circular interpolation. This delay ff1D is expressed by the following equation 1), assuming that the response from the speed and current control system (a) is very fast and the delay can be ignored.

DF/... (1) Here, F is the speed command value and K is the position loop gain. In conventional feedforward controllers, in order to compensate for the delay ff1D expressed by equation (1), the position command value It is multiplied by a certain constant gain α by a coefficient multiplier (12), and the output signal α·V is supplied to one input of an adder (5). The adder (5) has a position controller (
4) Adding the position control signal K-e supplied from the coefficient multiplier (12) and the output signal α·V from the coefficient multiplier (12) to create a speed command value F(6) that compensates for the delay, Supplied to speed and current control system (7). Usually coefficient multiplier (
The gain α of step 12) is set to α-1 if the response of the speed and current control system (7) is sufficiently fast and its delay can be ignored.

[Problems to be Solved by the Invention] In the conventional feedforward control device as described above, the feedforward compensation method employed in the device Since the dynamic characteristics of the control system are ignored, when applied to an actual system, there is a drawback that trajectory deviations occur due to respective tracking delays. Therefore, when performing highly accurate trajectory control, there is a problem in that the servo system designer needs to adjust the feedforward gain α in the actual system by trial and error.

The present invention was made to solve this problem, and it is an object of the present invention to obtain a highly accurate feedforward control device that does not require adjusting the feedforward gain α by trial and error for each actual system as in the past. With the goal.

[Means for solving the problem] The feedforward control device according to the first invention includes:
In a servo control device that controls the rotational position of a motor,
Feedforward control means performs feedforward control of the servo delay amount of the feedback loop using a speed command value, and as an adjustment rule for the speed feedforward gain of the feedforward control means, the product of the speed command value and the position error signal is used. By a method of sequentially adding increments proportional to the signal to the speed feedforward gain,
and feedforward gain automatic adjustment means for automatically adjusting the speed feedforward gain.

The feedforward control device according to the second invention includes:
In a servo control device that controls the rotational position of a motor,
Feedforward control means performs feedforward control of the servo delay amount of the feedback loop using a speed command value and an acceleration command value, and the adjustment rule for the speed feedforward gain of the feedforward control means is based on the speed command value and position deviation. By the method of sequentially adding an increment proportional to the product signal to the speed feedforward gain, and as an adjustment rule for the acceleration feedforward gain of the feedforward control means, the acceleration command value and the position deviation signal or the speed deviation signal and feedforward gain automatic adjustment means for automatically adjusting the velocity and acceleration feedforward gains respectively by a method of sequentially adding increments proportional to the product signal of and to the acceleration feedforward gain.

The feedforward control device according to the third invention includes:
In a servo control device that controls the rotational position of a motor,
Feedforward control means performs feedforward control of the servo delay amount of the feedback loop using a speed command value and an acceleration command value, and a speed feedforward gain of the feedforward control means is set to a predetermined constant value. As an adjustment rule for the acceleration feedforward gain of the forward control means, the acceleration feedforward gain is automatically adjusted by sequentially adding an increment proportional to the product signal of the acceleration command value and the position error signal to the acceleration feedforward gain. The feedforward gain setting and adjustment means is provided for adjusting the feedforward gain.

[Function] In this first invention, in a servo control device that controls the rotational position of a motor, feedforward control is performed on the servo delay amount of the feedback loop using a speed command value, and a method for performing the feedforward control is provided. The speed feedforward gain is automatically learned and adjusted by a method of sequentially adding increments proportional to the product signal of the speed command value and the position error signal to the speed feedforward gain.

In this second invention, in a servo control device that controls the rotational position of a motor, feedforward control is performed on the servo delay amount of the feedback loop using a speed command value and an acceleration command value, and in order to perform the feedforward control. The velocity feedforward gain is determined by a method of sequentially adding an increment proportional to the product signal of the speed command value and the position deviation signal to the speed feedforward gain, and the acceleration feedforward gain is determined by the method of adding an increment proportional to the product signal of the speed command value and the position deviation signal to the speed feedforward gain. Learning and adjustment are automatically performed by a method of sequentially adding increments proportional to the signal or the product signal with the speed deviation signal to the acceleration feedforward gain.

In this third invention, in a servo control device that controls the rotational position of a motor, feedforward control is performed on the servo delay amount of the feedback loop using a speed command value and an acceleration command value, and in order to perform the feedforward control. The velocity feedforward gain of is set to a predetermined constant value, and the acceleration feedforward gain is set by a method of sequentially adding an increment proportional to the product signal of the acceleration command value and the position deviation signal to the acceleration feedforward gain, Automatically learns and adjusts.

[Embodiment] FIG. 1 is a block diagram of a feedforward control device showing an embodiment of the first invention. In the figure (1)
- (11) are exactly the same as the above conventional device, and (
13) is a speed feedforward (hereinafter referred to as FF) gain variable device, and (14) is a learning controller.

The operation shown in FIG. 1 will be explained. The differences between Fig. 1 and Fig. 5 are the speed FF gain variable device (13) and the learning controller (
14) only. In the system shown in Fig. 1, when a position command value The value of the variable device (13) is successively changed so that the positional deviation value e converges to zero. The learning adjustment rule at this time is given by the following equations (2) and (3).

w (1) −w (1-1) + e (i-1)
・V (1-1)/r... (2) e (i) = X (1) Y (i)
--(3) Here, w (i) is the speed FF gain of the variable gain device (13) at sampling time i, and V (
1-1) is the differentiator (1
1) output (speed command value), X(1) is sample time i
, Y (1) is the position detection value (2) at sample time i, e (i-1) is the position deviation value at sample time (1-1), and τ is the learning controller (14 ) is the learning time constant of

The learning adjustment rule for the speed feedforward gain W1 shown in equations (2) and (3) is that the speed feedforward gain is automatically adjusted by sequentially adding an increment proportional to the product signal of the speed command value and the position error signal to the speed feedforward gain. This means obtaining velocity feedforward gain.

Therefore, the learning controller (14) calculates the observed positional deviation value e
The larger (1-1) is, the more the differential value of the position command value,
That is, the larger the speed command value V (1-1) is, the faster the speed FF gain w(i) of the variable gain device (13) is increased.

By performing the calculations of equations (2) and (3) at each control sampling time, automatic learning of the feedforward gain can be performed quickly.

By configuring the feedforward control device in this way, there is no need to set the optimum feedforward gain corresponding to the machine load by trial and error, and the gain can be varied adaptively in response to load fluctuations. ,
Highly accurate control with small follow-up delay can be performed.

In the above embodiment, the learning controller (14) is arranged for a feedforward control system using a speed command value, but this way of thinking is also applicable to a feedforward control system using an acceleration command value used in a servo system. It can also be applied to

FIG. 2 is a control system diagram of a feedforward control device showing a first embodiment of the second invention.

In the figure, (1) to (4) and (11) are exactly the same as in Figure 1, and (13-1) and (13-2) are variable gain devices for speed FF and acceleration FF, respectively. ,(
14-■) and (14-2) are learning controllers for speed FF and acceleration FF, respectively, and (15) is an addition and subtraction controller that performs addition and subtraction between the three human input signals and outputs a speed deviation signal e. (16) is a second-order differentiator, (17) is an adder, (1
8) is the velocity loop proportional gain, (19) is the velocity loop product (2), (20) is the inertia term of a motor, etc., and (21) is a position detector such as a pulse encoder.

The operation shown in FIG. 2 will be explained. In a servo system like the one shown in the figure, a differentiator (11) for the input position command value X (1)
It is shown that the delay in the position loop and the speed control loop can be compensated for by performing feedforward control on the velocity v1, which is the output of -1) and (13
-2) FF gain values W1 and W2 depend on the proportional gain K of the speed control system, the integral constant V number T, the inertia term J of the load, etc., and are difficult to fix easily. In the present invention, in the feedforward control system described above, learning controllers (14-1) and (14-2) are individually provided for the speed FF gain value W and the acceleration FF gain value W2, and the position deviation Each learning adjustment is performed based on the value e.

The learning adjustment rules at this time are the following formulas (4) and (5)% w (1) −W2 (1-1) + e (1-1
) ・A(1-1)/r2... (5) Here, Wl(1) is the speed FF gain at sample time i of the variable gain device (Ill-i), and w2(1) is the variable gain is the acceleration FF gain of the device (13-2) at sample time i, v (i-t) is the speed command value at sample time (i-1), and A (1-1) is the acceleration FF gain at sample time (i-1). ), τ1 is the learning time constant of the learning controller (13-1), and τ2 is the learning controller (
13-2) is the learning time constant.

In the embodiment shown in FIG. 2, the FF gains W2 and W2 for velocity and acceleration converge so that the positional deviation value e becomes zero. The convergence time in this case is determined by the learning time constants τ and τ2.

FF game of velocity and acceleration shown in equations (4) and (5)
The learning adjustment rule for speed feedforward gain w1 is based on the method of sequentially adding an increment proportional to the product signal of the speed command value and the position deviation signal to the speed feedforward gain, and The forward gain w2 means that the speed and acceleration feedforward gains are automatically obtained by sequentially adding increments proportional to the product signal of the acceleration command value and the position error signal to the acceleration feedforward gain. By configuring the control loop system as shown in FIG. 2, each FF gain for velocity and acceleration can be learned simultaneously.

FIG. 3 is a control system diagram of a feedforward control device showing a second embodiment of the second invention.

In the figure (1) to (4), (11), (13-1)
, (13-2), (14-1), (14-2), (15
) to (21> are exactly the same as in FIG. 2.

The operation shown in FIG. 3 will be explained. Fig. 3 shows a learning type FF control loop that improves the follow-up delay of the position control loop and the speed control loop. The difference from FIG. 2 is that the speed deviation value e is used. In this case, the speed FF gain W1 is adjusted so that the position deviation value e becomes zero, and the acceleration FF gain w2 is adjusted so that the speed deviation value e becomes zero.

That is, the acceleration FF gain w2 in FIG. 3 is automatically learned and adjusted by a method of sequentially adding increments proportional to the product signal of the acceleration command value and the speed deviation signal to the acceleration feedforward gain.

FIG. 4 is a control system diagram of a feedforward control device showing an embodiment of the third invention. In the figure, (1
) ~ (4) , (11), (13-2), (14-2)
, (15) to (21) are the same as in Figure 2, and (
12) is the same as in FIG.

The operation shown in FIG. 4 will be explained. Figure 4 shows a learning type FF control loop that improves the follow-up delay of the position control loop and velocity control loop like Figure 2, but the velocity FF gain α is fixed by the coefficient multiplier (12), and the acceleration FF gain w2
It differs from FIG. 2 in that only the following points are automatically learned and adjusted. By configuring such a control loop, the problem of mutual interference that occurs when simultaneously learning the two parameters, speed and acceleration FF gains W and W2 in the case of Fig. By automatically adjusting the acceleration FF gain w2 to compensate for the delay in the velocity loop system that depends on the inertia term J, it is possible to obtain a feedforward control device with significantly fewer trajectory errors than the conventional configuration. The learning adjustment rule in this case is similar to equation (5).

That is, the velocity feedforward gain of the feedforward control device shown in FIG. 4 is maintained at a predetermined constant value, and the acceleration feedforward gain of this control device increases in increments proportional to the product signal of the acceleration command value and the position error signal. The learning adjustment is automatically performed by the method of sequentially adding to the acceleration feedforward gain.

[Effects of the Invention] As described above, according to the present invention, the feedforward control device automatically learns and adjusts the velocity and acceleration feedforward gains for performing feedforward control, so the feedforward gain It is no longer necessary to find it by trial and error in an actual system, and the workability when adjusting equipment is greatly improved.

Furthermore, even when the dynamic characteristics of the servo system in an actual system fluctuate, it is possible to adapt and respond to those changes, achieving highly accurate servo control characteristics with little tracking error, and improving the performance of the device. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a feedforward control device showing an embodiment of this first invention, and FIG. 2 is a control system diagram of a feedforward control device showing a first embodiment of this second invention. 3 is a control system diagram of a feedforward control device showing a second embodiment of this second invention, and FIG. 4 is a control system diagram of a feedforward control device showing an embodiment of this third invention. FIG. 5 is a block diagram of a conventional feedforward control device. In the figure, (1) is the position command value X, (2) is the detected position value Y, (3) is the subtractor, (4) is the position controller, (5) is the subtracter, and (6) is the speed command value. F, (7) is the speed and current control system, (8) is the power amplifier, (9) is the servo motor,
(10) is a position detector, (11) is a differentiator, (12) is a coefficient multiplier, (13), (13(), (13-2)
) is a gain variable device, (14), (14-1), (1
4-2) is a learning controller, (15) is an adder/subtractor, (16)
is the second-order differentiator, (17) is the adder, (18) is the velocity loop proportional gain, (19) is the velocity loop integral term T, (20) is the inertia term J, and (21) is the position It is a detector.

Claims (3)

[Claims] (1) A servo control device that controls the rotational position of a motor, which includes a feedforward control means that performs feedforward control of a servo delay amount in a feedback loop using a speed command value, and a speed feedforward gain of the feedforward control means. Feedforward gain automatic adjustment means that automatically adjusts the speed feedforward gain by sequentially adding an increment proportional to a product signal of the speed command value and the position error signal to the speed feedforward gain as an adjustment rule. A feedforward control device comprising: (2) In a servo control device that controls the rotational position of a motor, the feedforward control means performs feedforward control of the servo delay amount of the feedback loop using a speed command value and an acceleration command value, and the speed of the feedforward control means. The feedforward gain is adjusted by a method in which increments proportional to the product signal of the speed command value and the position error signal are sequentially added to the speed feedforward gain, and the acceleration feedforward gain of the feedforward control means is adjusted. As a general rule, the speed and acceleration feedforward gains are automatically adjusted by sequentially adding increments proportional to the product signal of the acceleration command value and the position deviation signal or the speed deviation signal to the acceleration feedforward gain. A feedforward control device comprising feedforward gain automatic adjustment means. (3) In a servo control device that controls the rotational position of a motor, a feedforward control means that performs feedforward control of a servo delay amount of a feedback loop using a speed command value and an acceleration command value, and a speed of the feedforward control means The feedforward gain is set to a predetermined constant value, and as an adjustment rule for the acceleration feedforward gain of the feedforward control means, an increment proportional to the product signal of the acceleration command value and the position error signal is set to the acceleration feedforward gain. A feedforward control device comprising feedforward gain setting and adjustment means for automatically adjusting the acceleration feedforward gain by sequentially adding the acceleration feedforward gain to the acceleration feedforward gain.