JPH0628036A - Position Tracking Control Method for Position Synchronous Velocity Control System - Google Patents

Abstract

(57) [Abstract] [Purpose] In the position-synchronous speed control system, the position and speed are both fed back and controlled digitally, so that the limit on the scan time can be relaxed and the target response characteristics can be easily obtained. To be able to [Configuration] An acceleration compensation value DVDT is calculated by multiplying a value obtained by differentiating the speed command VREF by a system mechanical time constant T _M1 . This scan compensation value DVDT delay value 1 scan time (τ ₂ ) D
Torque command output by adding VDT1 to the output of speed controller 31
Get TREF1. The load 13 is torque-driven by the torque transmission delay element 12 to which the torque command output TREF1 is input.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method in a position-synchronous speed control system for feedback control of both position and speed, and more particularly to position-synchronous speed control in which control is performed based on a digital signal. The present invention relates to a position tracking control method in a system.

[0002]

2. Description of the Related Art A position-synchronous type speed control system is a system in which control is performed by feeding back both the position and speed of an electric motor. There are various types of position-synchronous speed control systems, one example of which is disclosed in Japanese Patent Laid-Open No. 61-273611. In the position-synchronous speed control system, the position control loop and the speed control loop have so far been configured by analog circuits, respectively, but with the recent development of micro CPUs and DSPs (digital signal processors), these control loops are controlled. It is common to digitize loops. FIG. 4 is a block diagram of a conventional position synchronization type speed control system which is digitized.

This position synchronization type speed control system is roughly classified into
The position control device 10 for generating the speed command VREF and inputting the position feedback PFB, the speed control device 11 provided on the output side of the position control device 10 for inputting the speed feedback NFB, the torque transmission delay element 12 including a motor, the torque transmission Position feedback of the load 13 connected to the delay element 12 and the position of the load 13 is detected.
The position detector 14 outputs PFB. The torque transmission delay element 12 is controlled by the torque command output T ₁ from the speed control device 11 to apply a torque T ₂ to the load 13.
It is driven by rotation. Here, assuming that the torque transmission delay time is T _I1 , the mechanical time constant is T _M1 , and the 100% level of speed is V ₁₀₀ , the transfer function of the torque transmission delay element 12 is 1 / (1 + T _I1 s) and the load 13 The transfer function is 1 / (T _M1
s), the transfer function of the position detector 14 is V ₁₀₀ / s.
A pulse generator (not shown) is connected to the load 13 to generate a velocity feedback NFB.

The position control device 10 includes a speed command control means 21 for generating a speed command VREF and a speed command VREF in a system 10.
A divider 22 that generates a normalized speed command NREF by dividing by 0% speed V ₁₀₀ , a multiplier 23 that multiplies the speed command VREF by the controller scan time τ _2, and a delay provided on the output side of the multiplier 23. It is constituted by an element 24, a position controller 25 having a gain of KPE and an integration time constant of T _I2 . The delay element 24 delays the output of the multiplier 23 by one scan time τ ₂ and adds the delayed result to the output of the multiplier 23. As a result, the output of the multiplier 23 is integrated for each controller scan time τ ₂ , and the position command PREF which is the integrated value of the speed command VREF is obtained. Position feedback PFB input to the position controller 10
Is obtained every scan time τ ₂ and becomes the position feedback PFB1 delayed by one scan. Position command PREF and position feedback PFB1
Is the position error PE, and this position error PE is input to the position controller 25. Position controller 2
5 is the gain KP for the position error PE under the condition of the integration time constant T _I2.
The position correction signal U _p is output by multiplying by E, and the position correction signal U _p and the normalized speed command NREF are added to give a value NPU. This value NPU is output to the speed control device 11 as the output NPU1 every scan time τ ₂ .

The speed controller 11 comprises a speed controller 31. The output NPU1 of the position control device 10 is acquired every servo scan time τ ₁ and becomes a speed command NPU2 delayed by one scan time. On the other hand, the velocity feedback NFB input to the velocity control device 11 is acquired every servo scan time τ ₁ and becomes the velocity feedback NFB 1 delayed by one scan. The difference NPU2-NFB1 between the speed command NPU2 and the speed feedback NFB1 is input to the speed controller 31. The output of the speed controller 31 is the torque command.
TREF, but this torque command TREF is the scan time τ
Torque transmission as the torque command output T _{1 per} delay element 1
It is designed to be output to 2. By thus constructing the position-synchronous speed control system, position and speed feedback control is performed. Here, the servo scan time τ ₁ and the controller scan time τ ₂ are parameters generated by digitizing the position synchronization type speed control system, and are units of data acquisition and calculation in the speed control device 11 and the position control device 10, respectively. Which is the control calculation time.

[0006]

In the above-described digitized conventional position-synchronous velocity control system, the length of each scan time τ ₁ and τ ₂ depends on the mechanical time constant T _M1 of the controlled object and the required specifications. When the required scan times τ ₁ and τ ₂ are short, it becomes difficult to obtain a target response characteristic with a low-speed CPU or DSP.
Since an extremely high speed CPU or DSP must be used, there is a problem that the cost increases. In particular, the constraint on the controller scan τ ₂ is a severer condition for the control system because the series of arithmetic processing amounts that must be executed during this scan time τ ₂ is large.

An object of the present invention is to provide a position tracking control method in a position synchronization type speed control system, which can relax the limitation on the scan time and can easily obtain a target response characteristic.

[0008]

A position tracking control method in a position-synchronous speed control system according to the present invention multiplies a value obtained by differentiating a speed command by a mechanical time constant of the position-synchronous speed control system. An acceleration compensation value is calculated, and a value obtained by adding the acceleration compensation value to the output of the speed control means is used as an input signal to the driving means.

[0009]

The value obtained by differentiating the speed command is the value of the acceleration that the system should take. The mechanical time constant is a parameter related to the time delay of control for the system. By adding the acceleration compensation value obtained by multiplying the value obtained by differentiating the speed command by the mechanical time constant to the output of the speed control means, it is possible to perform control in consideration of the acceleration to be taken and the time delay of the system. ,
The trackability of the speed of the actual load with respect to the target speed is improved, and at the same time, the error between the target position and the actual position can be reduced. As a result, if the same specifications are satisfied, the scan time can be lengthened as compared with the conventional method, and a low-speed CPU or DSP can be used.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of a position synchronization type speed control system used for implementing the present invention. This position-synchronous speed control system is different from the conventional position-synchronous speed control system described with reference to FIG. 4 in that an acceleration torque compensator 15 for performing acceleration torque compensation is added to the position control device 10, and the speed control is further performed. Adder 3 to device 11
It has a configuration in which 2 is newly added. Position control device 1
0, the speed command VREF from the speed command control means 21
Is output to the acceleration torque compensator 15. Therefore, this position synchronous speed control system
Position control device 10 including the acceleration torque compensator 15 to which the speed command VREF is generated and the position feedback PFB is input, position control device 1
A torque transmission delay element 1 including a speed control device 11, an electric motor, etc., which is provided on the output side of 0 and receives a speed feedback NFB.
2. A load 13 connected to the torque transmission delay element 12 and a position detector 14 that detects the position of the load 13 and outputs a position feedback PFB. Of these, the configurations of the torque delay transmission element 12, the load 13, and the position detector 14 are the same as those in the above-described conventional position-synchronous speed control system. The position control device 10 and the speed control device 1
1, and further, the acceleration torque compensator 15 in the position control device 10 is composed of a digital arithmetic unit such as a CPU and a DSP. One or several CPUs or DSPs
It is possible to realize the position control device 10, the speed control device 11, and the acceleration torque compensator 15, and it is desirable to do so in terms of cost.

The acceleration torque compensator 15 will be described below. The acceleration torque compensator 15 includes a delay element 41 that delays the speed command VREF, and a delay element 41 that delays the speed command VREF.
42, a divider 43 for dividing the output of the subtractor 42 by the controller scan time τ ₂ , and a multiplier 44 for multiplying the output of the divider 43 by the mechanical time constant T _M1 of this system. ing. The output of the multiplier 44, that is, the acceleration compensation value DVDT is output to the speed control device 11 as the acceleration compensation value DVDT1 delayed by one scan for each controller scan time τ ₂ .

The speed control device 11 includes a speed controller 31 and
It is composed of an adder 32 provided on the output side of the speed controller 31. The adder 32 is for adding the output of the speed controller 31, that is, the torque command TREF and the acceleration compensation value DVDT1. The acceleration compensation value DVDT1 is acquired every servo scan time τ ₁ and becomes a value delayed by one scan, and is supplied to the adder 32. The addition result of the adder 32 is output to the torque transmission delay element 12 as a torque command output TREF1 every servo scan time τ ₁ . The velocity feedback NFB is acquired every servo scan time τ ₁ and the velocity feedback N is delayed by one scan.
It becomes FB1 and the difference NPU2-NFB1 between the value NPU2 of one scan delay of the output NPU1 of the position control device 10 and the speed feedback NFB1 is input to the speed controller 31 as compared with the conventional control system described using FIG. It is the same.

Next, the operation of this embodiment will be described. In the acceleration torque compensator 15, the speed command VREF is delayed by the delay element 41.
And the subtracter 42, the output of the subtractor 42 is a value obtained by subtracting the speed command VREF1 one scan time before from the current speed command VREF. This subtraction result VREF-VRE
F1 is input to the divider 43 and divided by the controller scan time τ ₂ . This means that the change amount of the speed command VREF is divided by the scan time τ ₂ , so it is equivalent to obtaining the time derivative of the speed command VREF, and the output of the divider 43 is the derivative of the speed command VREF. It becomes a value. The differential value is multiplied by the mechanical time constant T _M1 of the system in the multiplier 44, and becomes the acceleration compensation value DVDT. The acceleration compensation value DVDT is output to the adder 32 of the speed control device 11 as an acceleration compensation value DVDT1 delayed by one scan for each controller scan time τ ₂ .

The position control device 10 generates the speed command VREF, receives the position feedback PFB, and outputs the value NPU1 as in the conventional device shown in FIG. The speed controller 11, speed feedback NFB is acquired for each servo scan time tau ₁ 1
Scan delay speed feedback becomes NFB1 and speed feedback with value NPU2
The deviation from NFB1 is input to the speed controller 31. The speed controller 31 integrates this deviation under the conditions of the proportional gain P and the integration time constant T _I , and the integration result TREF is added by the adder 32.
In, the acceleration compensation value DVDT1 is added to the one-scan delay value, and is output to the torque transmission delay element 12 as a torque command output TREF1 every servo scan time τ ₁ . The torque transmission delay element 12 torque-drives the load 13 based on the torque command output TREF1, and as a result, the load 13
Changes in speed and position. The speed of the load 13 is
Is detected by a pulse generator (not shown) connected to and is fed back to the speed control device 11 as a speed feedback NFB. The position of the load 13 is detected by the position detector 14 and is fed back to the position control device 10 as a position feedback PFB.

The position and speed of the load 13 are feedback-controlled as described above. In this position synchronization type speed control system, the acceleration compensation value DVDT is output to the output TREF of the speed controller 31.
The value obtained by delaying 1 by 1 scan is added, and the addition result is used as the torque command output TREF1, and this torque command output TREF1 is used as the drive signal for torque control in the torque transmission delay element 12, so that the load 13 uses the speed command VREF. Follows well and the position error PE is further reduced.

Next, in the position-synchronous speed control system of the present embodiment, the response with and without acceleration torque compensation (that is, the same as the conventional position-synchronous speed control system shown in FIG. 4). The result of comparison with the characteristics will be described. 2 is a response characteristic diagram when acceleration torque compensation is performed, and FIG. 3 is a response characteristic diagram when acceleration torque compensation is not performed. In measuring these response characteristics, the servo scan time τ ₁ and the controller scan time τ ₂ were each 1 msec, the speed control cutoff frequency ω c ^s was 300 rad / sec, and the gain of the position controller 25 was 50. did. Speed feedback NFB1 (but not normalized) when the same speed command VREF is given, position error PE, acceleration compensation value DV with 1 sample delay
Each DT1 is shown. It should be noted that the vertical axis scales for the speed command VREF and the speed feedback NFB1 are different between FIG. 2 and FIG.

As is apparent from these figures, in FIG. 3, that is, in the conventional method, the value of the position error PE is scaled out when the value of the speed command VREF is changing. The speed command VREF changes to a V shape, but if you check the convergence status of the position error at the shoulder part after swinging to the negative side once,
The time required for the position error PE to be within 0.1 mm is 26 msec in FIG. 2 and 44 msec in FIG.
From these facts, by performing acceleration torque compensation, even when the servo scan time τ ₁ and the controller scan time τ ₂ are each 1 msec, when the value of the speed command VREF changes, that is, acceleration / deceleration is performed. It can be seen that the followability of the speed when the vehicle is moving is improved and the fluctuation range of the position error PE is significantly reduced. Also, speed command
It can be seen that the position error PE converges quickly after the change of VREF.

[0018]

As described above, the present invention adds the acceleration compensation value obtained by multiplying the value obtained by differentiating the speed command by the mechanical time constant to the output of the speed control means to obtain the acceleration and the system to be taken. The control that takes into account the time delay of is carried out, the followability of the speed of the actual load to the target speed is improved, the error between the target position and the actual position is reduced, and the calculation control time is lengthened. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a position synchronization type speed control system used for implementing the present invention.

FIG. 2 is a response characteristic diagram when acceleration torque compensation is performed.

FIG. 3 is a response characteristic diagram when acceleration torque compensation is not performed.

FIG. 4 is a block diagram showing a configuration of a conventional position synchronization type speed control system.

[Explanation of symbols]

 10 Position Control Device 11 Speed Control Device 12 Torque Transmission Delay Element 13 Load 14 Position Detector 15 Acceleration Torque Compensator 21 Speed Command Control Means 22,43 Divider 23,44 Multiplier 24,41 Delay Element 25 Position Controller 31 Speed Controller 32 Adder 42 Subtractor

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G05B 11/36 Q 7531-3H H 7531-3H 503 A 7531-3H G05D 3/00 N 9179-3H

Claims (1)

[Claims] 1. A drive unit for driving a controlled object, a position command generated by integrating a given speed command, a position correction signal based on position feedback from the controlled object and the position command, and the speed. A position-synchronous speed having position control means for adding the position correction signal to a command and outputting the command, and speed control means for controlling the drive means based on the output of the position control means and speed feedback from the controlled object. In a position tracking control method in a control system, a value obtained by differentiating the speed command is multiplied by a mechanical time constant of the position synchronization type speed control system to calculate an acceleration compensation value, and the acceleration compensation value is set to the speed control. A position tracking control method in a position-synchronous speed control system, wherein a value added to the output of the means is used as an input signal to the driving means.