JP2001350525A - Positioning servo controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positioning servo controller which easily makes the best adjustment of a positioning state. SOLUTION: Feedforward controllers 12 and 13 perform feedforward control with feedforward gains Kff1 and Kff2, which have values of monotonous increase functions K1(Kg) and K2(Kg) containing an adjustment gain Kg as an argument. For the purpose, the values of the feedforward gains Kff1 and Kff2 can be varied at the same time by varying the value of the adjustment gain Kg, so the positioning state of a machine system can be adjusted to the best state only by adjusting the adjustment gain Kg.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a positioning servo controller for positioning a control target, and more particularly to a positioning servo controller for positioning a motor.

[0002]

2. Description of the Related Art FIG. 2 is a control block diagram showing a configuration of a conventional positioning servo controller. As shown in FIG. 2, the conventional positioning servo controller includes a position controller 1, a speed controller 2, a torque amplifier 3, a motor 4, and a differentiator 5. In this positioning servo controller, the inertia is J [N · m · s ² ].
Is to control the position θ [rad] of the motor 4.

[0003] The motor 4 is provided with an encoder (not shown) so that the position θ of the motor 4 can be detected by the encoder. The position deviation between the position command θ _r issued from the host device (not shown) and the position θ of the motor 4 is input to the position controller 1. The position controller 1 calculates the deviation as K _{p according} to the position loop gain K _p [1 / s].
A speed command ω _r [rad / s] to the motor 4 multiplies the multiplied value.
Is a proportional controller. The differentiator 5 differentiates the position θ [rad] of the motor 4 to calculate the speed ω [r
ad / s] is output. The speed controller 2 outputs the speed command ω _r
And enter a speed deviation between the speed of the motor 4 omega, outputs a value of the deviation and K _v multiplied by the speed loop gain K _v [1 / s] as the torque command T _ref to the motor 4 [N · m] It is a proportional controller. The torque amplifier 3 has a torque command T
_The motor 4 is driven by inputting _ref and generating a torque _Tr . That is, the positioning servo controller is for to follow the position theta of the motor 4 to the position command theta _r, the position theta of the motor 4, the position response to the position command theta _r.

In such a conventional positioning servo controller, a feedback control system for performing positioning control based on the position θ of the motor 4 fed back is used. As described above, the positioning servo controller usually has a velocity loop processing as a minor loop in the position loop processing. In such a feedback control type positioning servo controller, the values of the position loop gain K _p and the speed loop gain K _v are finite and have upper limits. Therefore, the position response theta motor 4, and the position command theta _r not completely coincide, so-called servo delay occurs.

As a method for eliminating such a servo delay, as shown in a positioning servo controller shown in FIG. 3, a speed feed-forward controller 6, an acceleration feed-forward controller 7, and the acceleration of motor 4 and an acceleration command are compared. There is a method of adding an acceleration controller 9 that performs acceleration feedback control based on the deviation and outputs a torque command to the torque amplifier 3. Speed feedforward controller 6, the position command θ obtained by differentiating the value of the _r, which is the first feed-forward gain feedforward gain K
_A first feedforward compensation amount obtained by amplification by _ff1 is output. The first feedforward compensation amount is added to the value output from the position controller 1. The acceleration feedforward controller 7 calculates a value obtained by differentiating the first feedforward compensation amount into a feedforward gain K which is a second feedforward gain.
The second feedforward compensation amount obtained by amplification by _ff2 is output. The second feedforward compensation amount is added to the value output from the speed controller 2.

[0006] In the positioning servo controller of FIG.
Even if the inertia J of the motor 4 is not clearly understood, setting an appropriate value to the value of the acceleration loop gain Ka of the acceleration controller 9 can eliminate the influence of the inertia J on the control response of the positioning controller. If the feed forward gain K _ff2 = 1, a transfer function that _receives the position command θ _r as input and outputs the position response θ as 1
As a result, the servo delay can be eliminated.

On the other hand, as a method for easily adjusting the positioning state of the position response θ by adjusting various control system parameters such as the position loop gain K _p and the speed loop gain K _v , a positioning servo shown in FIG. As a controller, there is a method including an amplifier 10 that after the position controller 1 and the speed controller 2 multiplies the input by K _g with the adjustment gain K _g . In this positioning servo controller, optimal adjustment of the positioning state of the position response θ can be easily performed by adjusting only the adjustment gain K _g without separately adjusting the position loop gain K _p and the speed loop gain K _v. it can.

FIG. 5 is a block diagram showing a configuration of a positioning servo controller using the above two methods. With such a positioning controller, as described above, the servo delay can be eliminated, and the optimum adjustment of the positioning state can be easily performed. 5 is a block diagram of the positioning servo controller shown in FIG.
(A), it can be deformed as shown in FIG. 6 (b). At this time, it is assumed that the gain of the torque amplifier is 1.

Normally, the shaft end of the motor 4 of the above-described positioning servo controller is connected to a mechanical system to be controlled by the controller. Generally, the adjustment gain K _g
If the value of the gain of the feedback control system can be greatly increased, the mechanical system can be regarded as a rigid body having a high natural frequency. When the value of the gain of the feedback control system, such as adjusting the gain K _g is not raised significantly, the mechanical system can be regarded as a low rigidity characteristic frequency is lower mechanical system.

When the mechanical system can be regarded as a rigid body having a high natural frequency, each feedforward gain K _ff1 , K _ff2 = 1 can be set, and the block diagram of FIG. It can be replaced as shown in the block diagram of FIG. Also, if the value of the acceleration loop gain K _a is sufficiently larger than the value of the inertia J, J / K _a =
Since it can be regarded as 0, the block diagram of FIG. 6C can be replaced with the block diagram of FIG. 6D.

FIG. 7A is a block diagram of a positioning servo controller including a mechanical system to be controlled. In FIG. 7A, the reaction force from the mechanical system 11 to the motor 4 is assumed to be negligibly small. theta _M the position of the motor, the theta _L position response of the mechanical system 11 connected to the motor 4, omega is the resonance frequency of the mechanical system 11, the ζ is the damping coefficient of the mechanical system 11. Assuming that the inertia of the mechanical system 11 is J _L and the spring constant is K, the value of ω is (K / J _L ) ^0.5 , and ζ is smaller than 1 when the mechanical system 11 is a vibration system. Here, feed forward gains K _ff1 , K _ff2 = 1,
When J / Ka is approximated to 0, the block diagram of FIG. 7A is approximated as the block diagram of FIG. 7B.

[0012] FIGS. 8-12 is a graph showing how the position command theta _r and position response theta _L variations of the conventional tracking servo controller of FIG. 8 to 12, the S-curve acceleration / deceleration of the motor acceleration / deceleration time is 0.03 [second], the movement time of the motor 4 is 0.06 [second], and the rotation angle of the motor 4 is 3 [rad]. Such a position command θr is input to the positioning servo controller. FIG.
12 to FIG. 12, the acceleration starts from 0 second, and the position command θ _r becomes 3 [rad] in 0.06 seconds. This time is defined as the command end time. Further, in FIGS. 8 to 12, when the error between the position command theta _r and position response theta _L is within the positioning completed width is assumed that the positioning of the position response theta _L has been completed, completion of positioning from the command completion time The time until is settling time. The positioning completion width is ± 0.5 [rad].

FIG. 8 shows how the position response θ _L varies when the mechanical system 11 is a rigid mechanical system and ω = 300 and ζ = 0.01. Each control _{parameters, K p = 20, K v} = 60, K g = 2, is set as the feedforward gain K _ff1 = K _ff2 = 1. As shown in FIG. 8, after the command completion time, the vibration of the position response theta _L is adapted within positioning completion width, already positioning of position response theta _L is the instruction end time has been completed.
Therefore, the settling time at this time is 0 seconds.

However, the rigidity of the mechanical system 11 is low and ω = 10
Assuming that the value is 0 and the values of the control parameters are the same as those in FIG. 8, a large amplitude vibration is generated in the position response θ _L as shown in FIG. Usually, in such a case, in order to suppress vibration, the adjustment gain K
Try to lower the value of _g .

FIG. 10 shows a low-rigidity mechanical system 1 similar to FIG.
10 is a graph showing a state of fluctuation of the position response θ _L when the value of the adjustment gain K _g is reduced from 2 to 1 among the values of the control parameters in FIG. However, as shown in FIG. 10, the vibration of the position response θ _L still does not converge, and the positioning of the position response θ _L is not completed even if 0.14 seconds have elapsed after the end of the command.

Therefore, the values of the feed forward gains K _ff1 and K _ff2 are reduced this time. FIG.
10 shows how the position response θ _L varies when the values of the feedforward gains K _ff1 and K _ff2 are changed from 1 to 0 among the control parameters in FIG. It is a graph. As shown in FIG. 11, when the feed forward gain K _ff1 = K _ff2 = 0, the amplitude of the vibration of the position response θ _L becomes small, the vibration converges within the positioning completion width, and the settling time is about 0.01.
2 seconds. However, the feed forward gain K _ff1
If = K _ff2 = 0, the effect of feedforward control is lost at all. Therefore, the feedforward gains K _ff1 , K _ff2 , and the adjustment gain K _g are adjusted again by trial and error, and the optimal adjustment of the positioning of the position response θ _L is performed. FIG. 12 is a graph showing how the position response θ _L varies when the feedforward gain K _ff1 = K _ff2 = 0.5 and the adjustment gain K _g = 1.5. In this case, the amplitude of the vibration of the position response θ _L becomes smaller than the positioning completion width, and the settling time becomes zero.

[0017] As described above, in the conventional positioning servo controller, adjust the gain K _g values and velocity feed forward gain K value and acceleration feedforward gain K values and adjusted while optimum adjustment of the positioning state of _ff2 of _ff1 It is carried out. However, since the adjustment of each control parameter described above is performed by trial and error, there is a problem that the adjustment takes time.

[0018]

As described above, in the conventional positioning servo controller, the adjustment gain and the feedforward gain are adjusted by trial and error to perform the optimal adjustment of the positioning state. Problem.

An object of the present invention is to provide a positioning servo controller capable of easily performing optimum adjustment of a positioning state.

[0020]

In order to solve the above-mentioned problems, a position control means for amplifying a position deviation between a position command issued from a host device and a position of a control target by a position loop gain and outputting the amplified position deviation. First amplifying means for amplifying a value output from the control means with an adjustment gain and outputting the amplified value, and first feedforward compensation obtained by amplifying a value obtained by differentiating the position command with a first feedforward gain Speed feedforward control means for setting a value obtained by adding an amount to a value output from the first amplifying means to a speed command; and a speed deviation between the speed command and the speed of the controlled object being amplified by a speed loop gain. Speed controlling means for outputting, a second amplifying means for amplifying and outputting a value output from the speed controlling means by the adjustment gain, A value obtained by adding a second feedforward compensation amount obtained by amplifying a value obtained by differentiating the first feedforward compensation amount by a second feedforward gain to a value output from the second amplifying means is referred to as an acceleration command. Acceleration feed-forward means, an acceleration control means for amplifying an acceleration deviation between the acceleration command and the acceleration of the control object by an acceleration loop gain and outputting the result as a torque command, and driving the control object based on the torque command. A positioning servo controller including a torque amplifier, wherein the value of the first feedforward gain and the value of the second feedforward gain are values of a function having the value of the adjustment gain as an argument. .

In the positioning servo controller of the present invention, by setting the values of the first feed forward gain and the second feed forward gain to values of a function having the adjustment gain as an argument, the positioning state can be adjusted only by adjusting the adjustment gain alone. Therefore, the optimal adjustment of the positioning state can be easily performed.

[0022]

Next, a positioning servo controller according to an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings, the components denoted by the same reference numerals all indicate the same components.

FIG. 1 is a control block diagram showing the configuration of the positioning servo controller of the present embodiment. The positioning servo controller of the present embodiment includes a velocity feedforward controller 6, an acceleration feedforward controller 7,
5 is different from the positioning servo controller of FIG. 5 in that a speed feedforward controller 12 and an acceleration feedforward controller 13 are provided instead of the above.

Each feedforward controller 12, 13
Is performs feedforward control by the feed-forward gain K _ff1, K _ff2, the value of the feed-forward gain K _ff1, K _ff2 the formula (1), and argument adjustment gain K _g as shown in (2) Monotonically increasing function K ₁ (K
_g ) and K ₂ (K _g ).

[0025]

(Equation 1)

Here, K _gmin and K _gmax are K _gmin <K
_The predetermined value is _gmax, and K _gmin is the minimum value of K _g .

In the positioning servo controller of this embodiment, even when the rigidity of the mechanical system is low and a vibration having a large amplitude occurs in the position response θ _L as shown in FIG. 9, the value of the adjustment gain K _g can be changed. , The values of the feed forward gains K _ff1 and K _ff2 can be changed at the same time.
Only by adjusting the adjustment gain K _g , the positioning state of the mechanical system can be easily adjusted to the optimum state as shown in FIG.

In the positioning servo controller of this embodiment, the functions K ₁ and K _{2 of the} feedforward gain are used.
Is a monotonically increasing function of a straight line, but the scope of the present invention is not limited to this, and the functions K ₁ and K ₂ of the feedforward gain may be curves if they are increasing functions. Good.

[0029]

As described above, in the positioning servo controller of the present invention, when adjusting the positioning state of the position response, the value of the feedforward gain is used as the value of the function using the adjustment gain as an argument. In addition, there is no need to adjust multiple control parameters separately,
Optimal adjustment of the positioning state of the mechanical system can be easily performed.

[Brief description of the drawings]

FIG. 1 is a control block diagram illustrating a configuration of a positioning servo controller according to an embodiment of the present invention.

FIG. 2 is a control block diagram showing a configuration of a conventional positioning servo controller of a feedback control system.

FIG. 3 is a control block diagram showing the configuration of a conventional feed-forward control type positioning servo controller.

FIG. 4 is a control block diagram showing a configuration of a conventional positioning servo controller of a feedback control method using an adjustment gain.

FIG. 5 is a control block diagram showing a configuration of a conventional positioning servo controller of a feedforward control method using an adjustment gain.

FIG. 6 is an equivalent block diagram of the control block diagram of FIG. 5;

7 is a block diagram showing a configuration of the positioning servo controller of FIG. 5 including a mechanical system to be controlled.

FIG. 8 is a graph showing a change in a position command and a position response when the rigidity of the mechanical system is high.

FIG. 9 is a graph showing a change in a position command and a position response when the rigidity of the mechanical system is low.

FIG. 10 is a graph showing a change in a position command and a position response when an adjustment gain value is adjusted.

FIG. 11 is a graph showing a change in a position command and a position response when a feedforward gain is adjusted.

FIG. 12 is a graph showing a change in a position command and a position response when an optimal adjustment of a positioning state is performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Position controller 2 Speed controller 3 Torque amplifier 4 Motor 5, 8 Differentiator 6, 7, 12, 13 Feedforward controller 9 Acceleration controller 10 Amplifier 11 Control object

Claims (1)

[Claims] 1. A position control means for amplifying a position deviation between a position command issued from a host device and a position of a control target by a position loop gain and outputting the amplified value, and amplifying a value output from the position control means by an adjustment gain. A first amplifying means for outputting a first feed-forward compensation amount obtained by amplifying a value obtained by differentiating the position command with a first feed-forward gain, from the first amplifying means. A speed feedforward control unit that sets a value obtained by adding the value to a speed command, a speed control unit that amplifies and outputs a speed deviation between the speed command and the speed of the controlled object by a speed loop gain, Second amplification means for amplifying the output value by the adjustment gain and outputting the amplified value; differentiating the first feedforward compensation amount; Acceleration feedforward means for setting a value obtained by adding a second feedforward compensation amount obtained by amplifying the value by a second feedforward gain to a value output from the second amplification means as an acceleration command; A positioning servo controller comprising: an acceleration control unit that amplifies an acceleration deviation between a command and the acceleration of the control target by an acceleration loop gain and outputs the amplified torque deviation as a torque command; and a torque amplifier that drives the control target based on the torque command. The positioning servo controller, wherein the values of the first feedforward gain and the second feedforward gain are values of a function having the value of the adjustment gain as an argument.