JPS61142999A - Control circuit for pulse motor - Google Patents

Abstract

PURPOSE:To accelerate decelerating the acceleration in coincidence with the curve of a pull-out torque characteristic when a drive pulse rate approaches its pull-out torque, thereby enhancing the maximum arriving frequency. CONSTITUTION:A counter 13 operates to count up from the movement starting time, the output pulse rate is accelerated in response to the accelerating/ decelerating characteristics written in a ROM15. When the deceleration starting time is detected by a comparator 12, the counter 13 counts down to decelerate the output pulse rate by the output of the ROM15. The comparator 12 detects the deceleration starting time. If the addressing value (the output of the counter 13) of the ROM15 previously exceeds the prescribed value, the address is secured to maintain the output pulse rate in the ordinary state, and the pulse rate is then decelerated after the prescribed time.

Description

[Detailed description of the invention] The present invention relates to a drive control circuit for a pulse motor.

Pulse motors are widely used because they are easy to handle and control. When attempting to move a drive mechanism at high speed using a pulse motor, it is necessary to control the acceleration and deceleration of the pulse motor by changing the pulse rate of drive pulses applied to the pulse motor. For example, when moving an XY table, it is necessary to shorten the moving distance per pulse, obtain high positional resolution, and ensure a moving speed above a certain level, and drive a pulse motor at a high hull rate.

In order to minimize the travel time in a central link mechanism such as an XY table, high acceleration is required for short-distance travel, and high speed is required for long-distance travel. However, the pullout torque characteristic of the pulse motor is expressed as shown in FIG. 1, and as the drive pulse rate F becomes higher, the torque T decreases. For example, when driving a pulse motor with a torque of Ta()Tb), the drive pulse rate F becomes ta(<tb). Therefore, when trying to perform acceleration/deceleration control with constant f load and constant acceleration, the torque and acceleration (angular acceleration) of the pulse motor are proportional, so the higher the acceleration, the higher the torque is required, and the highest frequency (pulse rate) The speed decreases and cannot be increased in speed.

An object of the present invention is to provide a pulse motor control circuit that increases both the acceleration and maximum speed of the pulse motor.

According to the present invention, the pulse motor has a constant acceleration (torque)
When the drive pulse rate approaches the pullout torque, the acceleration (torque) is lowered in accordance with the curve of the pullout torque characteristic, thereby increasing the maximum frequency and increasing the speed.

In the present invention, short-distance movement of a movable body such as an XY table can be shortened in time due to its high acceleration, and long-distance movement can be shortened in time due to its high-speed performance. In addition, there is no need to use an unnecessarily large rated motor to ensure high-speed, high-acceleration performance.

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

FIG. 2 is a circuit diagram of an embodiment of the present invention.

The pulse motor control circuit shown in the figure is a control circuit for a pulse motor that drives an XY table.

This pulse motor control circuit includes a latch circuit 1 that holds movement distance data up to a deceleration start position f for XY table movement.
1, a counter 13 that counts up and down its input according to the U input and D input, a comparator 12 that compares the outputs of the counter 13 and the latch circuit 11 and generates a pulse when they match, and the output of the counter 13 An address clamp 14 that clamps the output level when it exceeds a certain value, a read-only memory (ROM) 15 in which data on acceleration/deceleration characteristics of the pulse motor is written, and R
■/F converter 18 that varies the output pulse interval according to the voltage of the signal obtained by converting the output of OM15 from analog to digital /CW), and a counter 19 that counts the distance traveled by the output of the gate.

In this embodiment, the counter 13 counts up from the start of movement, accelerates the output pulse rate according to the acceleration/deceleration characteristics written in the ROM 15, and when the comparator 12 detects the start of deceleration, the is counted down and the output pulse rate is decelerated by the output of the ROM 15. Furthermore, if the address specified value in the ROM 15 (output of the counter 13) exceeds a predetermined value before the deceleration start point is detected by the comparator 12, the address is fixed and the output pulse rate is kept in a steady state, and the deceleration is decelerated for a certain period of time. do.

Next, embodiments of the present invention will be described in more detail.

The counter 19 is set with travel distance data from the data bus 30 upon generation of the travel length set signal 40. Simultaneously with setting movement distance data to the counter 19, the movement distance data up to the start of deceleration is set in the latch circuit 11. This is because when acceleration and deceleration are performed reversibly, the deceleration start position is the half point of the total movement, so the latch circuit 1
This is because the distance data output when the counter 19 is set can be shifted one pit in the direction of I and 8B and latched at the same time. After setting the data, the start pulse 50 sets the moving direction of the clip 70 and the knob 21, sets the 7 lip-flop 20 to the start state, and clears the counter 13. The flip-flop 21 outputs driving pulses for forward and reverse rotation. Furthermore, the 7-rip 70 tube 20 maintains its output until the output of the cuff 19 or the stop signal 6o is applied.

After the start, counter 13F! , V/F until deceleration start point
The output pulses of the comparator 18 are counted up and the moving length counter 19 is counted down. There are as many address clamps 14 as there are address lines of the ROM 15. The number counted up by the counter 13 is the ROM
15, the output of the gate 16 becomes 11" and the ROM 15 of the address clamp 14
clamp the output address to the highest value (eg, FFFF).

This situation is shown in FIG. In the figure, the horizontal axis is the count pulse number of the counter 13, and the vertical axis is the designated address of 0M15. In addition, there are cases where the travel distance is long and the vehicle accelerates to the maximum speed (■), and cases where the maximum speed is not reached (II).
It is.

In case (I), the counter 13 counts up after the start of movement, and when it reaches the highest address in the ROM 15 (point 1), the address line is clamped to the highest address by the address clamp 14 and gate 16. , the counter 13 counts up to the deceleration start point.

Thereafter, when the deceleration start point set in the latch circuit 11 is reached, the comparator 12 generates a pulse, switches the output of the 7-lip flop 22, and switches the counter 13 to countdown operation. Countdown progresses and point 2
When it reaches , the clamp by the address clamp 14 is released, the address of the ROM 15 changes (decreases), and the output pulse is decelerated.

In case (II), acceleration/deceleration is performed without address clamping.

Next, the data written in the ROM 15 will be explained. Generally, between acceleration α, travel distance, and speed V, v=5 is set during acceleration and deceleration.
There is the relationship (1). On the other hand, the moving distance is proportional to the number of pulses, and the speed V is the output frequency of the V/F converter 18, that is, the digital/analog (D/A) converter 17.
is proportional to the digital input. Therefore, 80M data is output to ROM15 oc, Fienin 1F A; stone? 【sword)
...If data such as (2) is written, acceleration/deceleration control of the pulse motor can be performed using constant acceleration.

In this embodiment, this is further developed so that when L becomes large in equation (1), the acceleration α becomes small. This is the same thing as reducing torque and increasing the maximum achievable speed. In other words, according to the pullout torque characteristic shown in FIG. 1, the relationship between drive pulse rate F and torque T is aacT=g(F)oeg(V) --
Using (3) (g is a function of torque characteristics), a relationship is found for changing the acceleration α in equation (1) according to the drive pulse rate F, that is, the speed V.

That is, from equations (1) and (3), LocV”/g
(V) ・−・−−−−−−−−
(4) becomes. Therefore, the relationship is the same as in equation (2) <(4
) To write data that satisfies the formula to ROM, input the ROM address c,: (ROM data output)
27g (ROM data output) Data that satisfies the relationship (5) may be used.

As explained above, by using the present invention, a pulse motor control circuit having both high acceleration and high speed can be realized, and
When used as a Y table, etc., it can shorten handling time.

Fig. 2 is a circuit diagram of an embodiment of the present invention;
FIG. 3 is a diagram for explaining the operation of FIG. 2.

11... Latch circuit, 12... Comparator, 13... Acceleration/deceleration control counter, 14
...Address clan; 7', 15...
RIOML 17...D/A converter, 18
......V/F converter, 19...Counter, 20, 21, 22...7 lips, 70 tubes.

Claims (1)

[Claims] A pulse motor control circuit that generates pulses for driving a pulse motor, including a pulse generation circuit that changes a pulse rate generated according to a torque vs. drive pulse rate characteristic of the pulse motor during acceleration/deceleration control, and wherein the pulse rate is high. 1. A pulse motor control circuit characterized in that the pulse motor control circuit is capable of stably driving up to a high speed without step-out by gradually lowering the acceleration according to the characteristics as the motor speed increases.