JPH03128687A - Position control method for motor - Google Patents

Abstract

PURPOSE:To reduce the quantity of revolution up to stoppage and vibro-motive force given to a work by turning a motor by using a command pattern as a speed change, in which no displacement is generated between the motor and the work, in the greater part of the quantity of the motor rotated and revolving the motor at low speed within a range including a trigger signal. CONSTITUTION:A position command controller 3 checks the count (PZ) of a counter 8 and the integrated value PM of command pulses stored in a RAM 5, and recognizes these difference PM-PZ as a positional deviation Pe. The positional deviation Pe represents the difference of a command position generated by the follow-up delay of a motor and an actual location. When the position command controller 3 receives a trigger signal, it draws a deceleration pattern during a speed command pattern by using the pulse number only of a Ps-Pe section, and outputs a positional command value on the basis of the deceleration pattern. Accordingly, the motor is stopped by the fixed quantity of stoppage and revolution.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a motor position control method in which the rotational position of a motor is feedback-controlled and the motor is stopped when a trigger signal is input from the outside.

<Prior art> As a method for controlling the position of a motor, a position command value is calculated based on a speed command pattern that represents a temporal change in the command value of the motor's rotational speed, and position feedback is performed according to this position command value. There is something that controls it.

In this control method, the position command value is calculated as follows.

FIG. 4 is a diagram showing an example of a speed command pattern.

In performing position control, the speed command pattern is divided into sections at regular time intervals, and a position command value is calculated based on the area of the speed command pattern in each section 'l', . . . T2, . . . TN.

Then, the calculated position command value is in the interval 'T'+, T2
...'rN is given to the position control unit at regular intervals according to the order.

In such a control method, the motor is stopped when a trigger signal is received from the outside.

<Problem that the invention seeks to solve> However, this control method has the following problems.

■In the speed command pattern that is the basis of the position command,
Since a stop trigger signal is input during high-speed constant-velocity driving,
The amount of rotation from when the motor receives the trigger signal until it stops takes a large value.

■Since the speed command pattern is trapezoidal, if the motor and the workpiece to which motor power is supplied are configured to slip in response to impact, the position between the workpiece and the motor may be affected due to speed fluctuations. There was a problem in that misalignment occurred. Hereinafter, the fII impact applied to the workpiece due to a change in the driving speed of the motor will be referred to as the excitation force.

The present invention was developed to solve these problems, and the amount of rotation required for the motor to stop is small.
Moreover, it is an object of the present invention to realize a method for controlling the position of a motor that exerts a small vibrational force on a workpiece.

Means for Solving the Problems> The present invention divides a speed command pattern representing a change over time in the command value of the motor's rotational speed at regular time intervals, and determines the position based on the area of the speed command pattern in each section. In a motor position control method that calculates a command value as needed, performs feedback control of the motor rotational position based on the calculated position command value, and stops the motor when a trigger signal is received, this is the range at which the trigger signal is received. If it is known in advance, the motor is rotated based on a speed command pattern that produces a speed change that does not cause a deviation between the motor and the workpiece to which motor power is applied, and the motor is rotated within the range at the time the trigger signal is input. , a motor position control method characterized in that the motor is rotated at a speed command value lower than the speed of the set speed command pattern.

According to the present invention, most of the rotation amount of the motor is rotated using a speed command pattern with speed changes that do not cause misalignment between the motor and the workpiece, and a low speed is used within the range where a trigger signal is received. Rotate the motor with a small amount of rotation and stop it.

<Example> The present invention will be explained below using the drawings.

FIG. 1 is a diagram showing an example of the configuration of a position control system used for implementing the present invention.

In the figure, 1 is the motor to be controlled, and 2 is the motor.

This is a rotation sensor that detects one rotational position and outputs encoder pulses with a number of pulses proportional to the detected position.

Reference numeral 3 denotes a position command controller that performs calculations for calculating a position command value from a speed command pattern as described above, controls for stopping the motor when a trigger signal is received, and other controls.

4 is a ROM in which software for calculating position command values is stored, and 5 is a RAM in which data and variables necessary for calculation are stored.

Reference numeral 6 denotes a pulse output circuit that converts a digital position command value given from the controller 3 at regular intervals into a command pulse in which a number of pulses corresponding to the digital value are arranged during a certain period of time and outputs it.

7 is a position control section that constitutes a servo system having a position control loop together with the motor 1 and rotation sensor 2. 6 The position control section 7 is based on the command pulse from the pulse output circuit 6 and the encoder pulse from the rotation sensor 2. A drive current is applied to the motor 1 to perform feedback control of the rotational position. Furthermore, the encoder pulse outputted by the rotation sensor 2 is directly outputted, and this output is used to monitor the actual rotational position of the motor.

8 is a counter that counts the number of encoder pulses that have passed through the position control section 7. Based on this count, the position command controller 3 recognizes the actual rotational position of the motor. Further, the integrated value of this count is stored in the RAM 5 by the position command controller 3 at any time.

A sensor 9 provides a trigger signal to the position command controller 3 to stop the motor.

The operation of the system configured in this way will be explained.

FIG. 2 is a diagram showing an example of a speed command pattern, in which the solid line portion is the speed command value, and the broken line portion is a pattern representing the actual rotational speed of the motor.

Such a speed command value pattern is used when it is known in advance that the amount of rotation of the motor until the trigger signal is input is within a certain range.

As shown in the figure, the speed command value pattern has a trapezoidal pattern with rounded corners.

This roundness is designed to prevent misalignment between the motor and the workpiece due to the vibrational force exerted on the workpiece due to changes in speed over time. Then, in the range at which the trigger signal enters,
The speed command value is set to a value lower than the trapezoidal speed command pattern described above.

With this pattern of speed command values, the motor is controlled by using a speed command pattern that suppresses the excitation force on the workpiece for most of the motor's rotation amount, and by rotating the motor at a low speed within the range where the trigger signal is received. Stop with a small amount of rotation.

Next, a specific stopping operation will be explained.

When the system receives a trigger signal, it is generally impossible for the motor to stop instantaneously without having any stopping rotation amount. For this reason, the amount of rotation at which the motor stops after the system receives the trigger signal is stored in the memory 5 as a parameter. This parameter determines the rotor's inertia and
It is given by the number of pulses ps that should be generated from the pulse output circuit 6 from the time the trigger signal is received until the motor is stopped, based on the deceleration characteristics determined by the load applied to the motor.

The position command controller 3 outputs the position command value to the pulse output circuit 6, and calculates the cumulative value of command pulses indicating how many pulses the pulse output circuit 6 has generated after outputting the first position command value. The data is stored in the RAM 5 in a format that is refreshed each time the data is used.

A counter 8 counts the integrated value of encoder pulses. l) The count corresponds to the actual rotational position of the motor.

When the position command controller 3 receives the trigger signal,
The count Pz of counter 8 at this point and the RAM
The integrated command pulse ff1P- stored in 5 is checked, and the difference p and -pz between them is recognized as the positional deviation Pe. This positional deviation Pe is the difference between the command pulse product 31: value P and the integrated value of the encoder pulse, and is therefore the difference between the command position and the actual position caused by the follow-up delay of the motor. This difference varies depending on the operating state of the motor and remains in the position control section 7 as a pulse pool. Hereinafter, such a difference will be referred to as a servo stagnation.

When a trigger signal is received, if you immediately enter the stop operation without rotating the motor further by the amount of servo sag, the motor can be stopped at a constant stop rotation amount regardless of the servo's sag. can. From this, when the position command controller 3 receives the trigger signal, the ps-
A deceleration pattern is drawn in the speed command pattern using the number of pulses equal to p, and a position command value is output based on this pattern.

As a result, the motor is stopped at a constant stop rotation amount.

FIG. 2 shows the area of the portion corresponding to the number of pulses of PM, Pz, Ps, and Ps-Pe.

The position, acceleration, and movement determined from such a speed command pattern are as shown in FIG.

In the figure, the movement is the differentiation of acceleration. The trigger signal is generated when the motor rotation amount is between 87 and S8, that is, from time T7.
Attach the receiver during T8.

Effect〉 Such a system provides the following effects.

■Since most of the motor's rotation amount uses a speed command pattern that suppresses the vibrational force applied to the workpiece, it is possible to prevent misalignment between the motor and the workpiece.

- Near the point in time when the trigger signal is received, the motor is operating at a lower speed than the normal operating speed, so the amount of rotation of the motor from receiving the trigger signal to stopping can be reduced.

(2) When a trigger signal is received, a deceleration pattern is created using the number of pulses subtracted from the number of pulses ps required to stop the servo at this point, and the motor is stopped based on this deceleration pattern.

As a result, the motor can be stopped at a constant rotation amount regardless of the servo slack value, and stable repeatability of the stop position can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a position control system used to implement the present invention, FIGS. 2 and 4 are diagrams showing an example of a speed command pattern, and FIG. 3 is a diagram showing the speed command pattern of FIG. 2. FIG. 3 is a diagram showing changes over time in position, acceleration, and movement determined from DESCRIPTION OF SYMBOLS 1...Motor, 2...Rotation sensor, 3...Position command controller, 5...RAM, 6...Pulse output circuit, 7...Position control unit, 8...Counter. Figure 2: Gai, Hong□, Shigeru-P, Ps-P! !

Claims (1)

[Scope of Claims] A speed command pattern representing a change over time in a motor rotational speed command value is divided into sections at regular intervals, and a position command value is calculated at any time based on the area of the speed command pattern in each section, In a motor position control method in which the rotational position of the motor is feedback-controlled based on the calculated position command value and the motor is stopped when a trigger signal is received, if the range at which the trigger signal is received is known in advance. , the motor is rotated based on a speed command pattern set to a speed change over time that does not cause a deviation between the motor and the workpiece to which motor power is applied, and the set A motor position control method comprising rotating a motor at a speed command value lower than the speed of a speed command pattern.