JP2008152523A - Position control device and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position control device having a position estimation device which makes accurate position control even in the vicinity of a set position by feeding back an estimated position one sampling time from now, and also to provide a control method therefor. <P>SOLUTION: The position control device comprises: a position control part 1 which generates a speed instruction from a position deviation between a position instruction and a position estimated value; a speed control part 2 which generates a torque instruction from a speed deviation between the speed instruction and a speed estimated value; and a torque control part 3 which drives a control object, based on the torque instruction. The control device further comprises: a position storage part 4 which stores the position of the control object as position data for each sampling time; a position estimation part 5 which generates the position estimated value one sampling time from now; and a speed estimation part 6 which generates the speed estimated value from the position estimated value one sampling time from now and the current position data. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position control apparatus and its control method used for feedback by estimating a future position for one sampling time from only a plurality of past position data without using a model to be controlled.

A position control apparatus having a conventional position estimation apparatus is disclosed in, for example, Patent Document 1 and Non-Patent Document 1. The conventional position control device of Patent Document 1 gives a model to be controlled to be subjected to position control to the position estimation device, and estimates the current position from the obtained state quantity. Further, the conventional position control device of Non-Patent Document 1 uses a second-order integration system as a model to be controlled.
FIG. 3 is a block diagram of a conventional position control device disclosed in Patent Document 1. In FIG. In FIG. 3, 111 is a subtractor for subtracting the position command r and the position x, 112 is a position controller, and 113 is a control target. The inside of the broken line 120 is an observer. 114 is a subtractor, 115 is a force-to-speed transfer function, M is mass, 116 is a subtractor, 117 is a speed-to-position transfer function, 118 is a position feedback gain, 119 is a speed feedback gain, The dynamic characteristics of the controlled object and the controller are used as a dynamic model. x hat is a position estimation signal.
JP-A-5-94202 (page 5-7, FIG. 1) Michio Nakano, Shigeru Futami, Yuzo Yoshida, “Servo Technology and Power Electronics”, Kyoritsu Publishing Co., Ltd., September 20, 1994, p. 159

FIG. 4 is a block diagram for explaining the operation of the position estimation apparatus of the conventional position control apparatus of FIG. When the position command output is completed and the position deviation becomes ± 1 pulse or less, the response of the continuous system shown in FIG. 3 becomes inaccurate, and the position feedback and speed feedback are switched to the switches SW1 (121) and SW2 ( 122), feedback is provided intermittently. Therefore, if the position deviation is ± 1 pulse or less, the response phenomenon cannot be accurately estimated. As described above, the conventional position control device has a problem that correct position estimation is not performed in a state where the position deviation is small, causing a positioning error, an overshoot, and a ± 1 pulse vibration. It was.
The present invention has been made in view of such problems, eliminates a model for position estimation, estimates the position of one sampling time in the future from only a plurality of past position data, and determines the future of one sampling time in the future. An object of the present invention is to provide a position control apparatus having a position estimation apparatus that can feed back an estimated position and perform correct position control even in the vicinity of a settling position, and a control method therefor.

In order to solve the above problem, the present invention is configured as follows.
The invention according to claim 1 is a position control unit that generates a speed command from a position deviation of a position command and a position estimation value; a speed control unit that generates a torque command from the speed deviation of the speed command and the speed estimation value; A position control device comprising: a torque control unit that drives a control object based on the torque command; a position storage unit that stores the position of the control object as position data for each sampling time; and a position estimation for one sampling time in the future A position estimation unit that generates a value; and a speed estimation unit that generates a speed estimation value from the position estimation value in the future of the one sampling time and the current position data.
According to a second aspect of the present invention, in the position control device according to the first aspect, the position storage unit includes a plurality of past position data x _j (j = −N, − (N−1),. 1) is stored.
According to a third aspect of the present invention, in the position control device according to the second aspect, the position estimation unit generates a position estimated value based on a plurality of past position data and the expressions (1) to (9). It is characterized by doing.

Here, d1 is a position difference, d2 is a second-order difference in position, S ⁻ is an average acceleration, u ^{^} _i-1 is an estimated value of position increment at (i-1) time, and u ^{^} _i is a position at (i) time. Increment estimated value, u ^{^} _{i + 1} is an estimated value of position increment at (i + 1) time, e _i is a position prediction error, A, B, and C are constants determined from the number of data. Then, a = 2 / (N + 1), b = 1-a, A = 1-b ³ , B = (3/2) * (1-b ² ) * (1-b), C = (1 / 2) * (1-b) ³
According to a fourth aspect of the present invention, in the position control device according to the second aspect, the speed estimation unit estimates the speed based on the position estimated value in the future of the one sampling time, the current position data, and the equation (10). A value is generated.

Here ^{v ^} is the speed estimate, _{T s} is the sampling time.
According to a fifth aspect of the present invention, in the position control device according to the third aspect, the position estimating unit changes the number of past continuous position data according to the magnitude of the position deviation.
According to a sixth aspect of the present invention, in the position control device according to the third aspect, the position estimation unit changes the number of sampling times of past position data according to the magnitude of the position deviation.
The invention according to claim 7 is a position control unit that generates a speed command from a position deviation of a position command and a position estimation value, a speed control unit that generates a torque command from the speed deviation of the speed command and the speed estimation value, A step of storing the position of the control object as position data for each sampling time, and a position one sampling time in the future, in a control method of a position control device comprising: a torque control unit that drives the control object based on the torque command; A step of generating an estimated value; a step of generating a speed estimated value from the position estimated value in the future of the one sampling time and the current position data; a step of generating a speed command from the position command and the position estimated value; Generating a torque command from the estimated speed value.

According to the first to third aspects of the present invention, a position control within ± 1 pulse can be configured, and a position control device that controls the deviation with a resolution of 1 pulse or less can be provided.
According to the invention described in claim 4, it is possible to provide a position control device that can increase the speed estimation accuracy and constitute a speed control system with high resolution.
According to the fifth aspect of the present invention, it is possible to provide a position control device that controls from a large deviation to a small deviation with high accuracy by using an optimum number of data.
Further, according to the invention described in claim 6, it is possible to provide a position control device that suppresses vibration within ± 1 pulse.
Further, according to the seventh aspect of the present invention, it is possible to provide a position control method capable of configuring position control within ± 1 pulse and controlling the deviation with a resolution of 1 pulse or less.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of a position control device of the present invention. In FIG. 1, 1 is a position control unit, 2 is a speed control unit, 3 is a torque control unit, 4 is a position storage unit, 5 is a position estimation unit, 6 is a speed estimation unit, 7 is a control target, and 8 is a position detector. It is. The difference between the present invention and the position control device of the prior art is that the position estimation value and the speed estimation value are fed back and the position estimation is performed by equations (1) to (9).

Here, d1 is a position difference, d2 is a second-order difference in position, S ⁻ is an average acceleration, u ^{^} _i-1 is an estimated value of position increment at (i-1) time, and u ^{^} _i is a position at (i) time. Increment estimated value, u ^{^} _{i + 1} is an estimated value of position increment at (i + 1) time, e _i is a position prediction error, A, B, and C are constants determined from the number of data. Then, a = 2 / (N + 1), b = 1-a, A = 1-b ³ , B = (3/2) * (1-b ² ) * (1-b), C = (1 / 2) * (1-b) ³

The operation of the position estimation method of the present invention is as shown in the estimated value of the sine wave signal shown in FIG. 6 and the parabolic signal shown in FIG. The graph shown on the left of FIG. 6 is an estimated value of a sine wave signal having an amplitude of 1 and a period of 2π, and the graph on the right of FIG. 6 is a graph of a position estimation error. The maximum position estimation error is as small as about 2.5 × 10 ⁻⁸ . The graph shown on the left of FIG. 7 is an estimated value of the parabola, the graph shown on the right of FIG. 7 is a graph of the position estimation error, and the maximum estimation error is as small as −8 × 10 ⁻⁴ . As described above, if the position estimation method of the present invention is used, position estimation can be performed with a very small estimation error, so that position control with high accuracy is possible even when the position is within ± 1 pulse.

FIG. 7 is a flowchart showing a control method of the control device of the present invention. In step ST1, the position of the control target is stored as position data for each sampling time, in step ST2, a position estimation value in the future of one sampling time is generated, and in step ST3, the position estimation value in the future of one sampling time and the current position data are generated. Is generated from the position command and the position estimated value in step ST4, and a torque command is generated from the speed command and the estimated speed value in step ST5.
In this way, the configuration is as shown in FIG. 1, and the position is estimated by the equations (1) to (9) shown in the equation 1, so that the position can be estimated with high accuracy and the position deviation is ± 1 or less. Position control with high accuracy can be realized even in the region.

The block diagram of the position control apparatus which shows 1st Example of this invention. The block diagram which becomes the basis of the position estimation method of this invention Block diagram showing operation when deviation of conventional position control device is small Block diagram of a conventional position control device Graph showing estimated value and estimation error of sinusoidal signal by position estimation method of the present invention The graph which represents the estimated value and estimation error of the parabola signal by the position estimation method of this invention The flowchart which shows the control method of the position control apparatus of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Subtractor 2 Controller 3 Control object 4 Position detector 5 Position memory | storage device 6 Position estimation apparatus 101 Subtractor 102 Transfer function from force to speed 103 Transfer function from speed to position 111 Subtractor 112 Controller 113 Control object 114 Subtractor 115 Force to Speed Transfer Function 116 Subtractor 117 Speed to Position Transfer Function 118 Position Feedback Gain 119 Speed Feedback Gain 120 Position Observer 121 Position Feedback Switch 122 Speed Feedback Switch

Claims (7)

A position control unit that generates a speed command from the position command and a position deviation of the position estimation value, a speed control unit that generates a torque command from the speed command and the speed deviation of the speed estimation value, and a control target based on the torque command In a position control device comprising a torque control unit for driving,
A position storage unit that stores the position of the control target as position data for each sampling time;
A position estimation unit that generates a position estimation value for one sampling time in the future;
A speed estimation unit for generating a speed estimation value from the position estimation value in the future of the one sampling time and the current position data;
A position control device comprising: The position storage unit stores a plurality of past position data x _j (j = -N,-(N-1), ..., 1), where i is the current time. The position control device according to 1. The position control device according to claim 2, wherein the position estimation unit generates a position estimation value based on a plurality of past position data and Expressions (1) to (9).

Here, d1 is a position difference, d2 is a second-order difference in position, S ⁻ is an average acceleration, u ^{^} _i-1 is an estimated value of position increment at (i-1) time, and u ^{^} _i is a position at (i) time. Increment estimated value, u ^{^} _{i + 1} is an estimated value of position increment at (i + 1) time, e _i is a position prediction error, A, B, and C are constants determined from the number of data. Then, a = 2 / (N + 1), b = 1-a, A = 1-b ³ , B = (3/2) * (1-b ² ) * (1-b), C = (1 / 2) * (1-b) ³ The position control device according to claim 2, wherein the speed estimation unit generates a speed estimation value based on the position estimation value in the future of the one sampling time, the current position data, and Equation (10).

Here ^{v ^} is the speed estimate, _{T s} is the sampling time.   The position control device according to claim 3, wherein the position estimation unit changes the number of past consecutive position data according to the magnitude of the position deviation.   The position control device according to claim 3, wherein the position estimation unit changes a sampling time of past position data according to a size of a position deviation. A position control unit that generates a speed command from the position command and a position deviation of the position estimation value, a speed control unit that generates a torque command from the speed command and the speed deviation of the speed estimation value, and a control target based on the torque command In a control method of a position control device comprising a torque control unit for driving,
Storing the position of the control object as position data for each sampling time;
Generating a position estimate in the future of one sampling time;
Generating a speed estimate from the position estimate of the one sampling time future and the current position data;
Generating a speed command from the position command and the estimated position value;
Generating a torque command from the speed command and the estimated speed value;
A control method of a position control device comprising: