JPH0264716A - Positioning device with pulse motor - Google Patents

Abstract

PURPOSE:To position with good accuracy regardless of a maximum speed, acceleration and deceleration ratio and an initial velocity and to shorten positioning time by providing a pulse motor controller having a setting switch, a counter circuit, a pulse generator, etc. CONSTITUTION:When an object is positioned in a target position, first, the target position is inputted to a counter circuit 8 by the operation of a setting switch 9 in a pulse motor controller 3. Next, a slow stop position is also inputted to the circuit 8 through a switch 9 and the circuit 8 performs the operation of what point of time a motor 1 is decelerated from the input values. When the distance to the target position is comparatively short, a deceleration is executed from the halfway of an acceleration through a pulse generator 12, etc., without performing a high-speed operation. When the distance is long, the high-speed operation is performed, and when the distance to the target position becomes fixed, the motor 1 is driven by a low-speed operation pulse and the object reaches the target position slowly. Thus, the positioning is attained with good accuracy regardless of the maximum speed, the acceleration and deceleration ratio and the initial velocity and the positioning time can be shortened.

Description

[Detailed Description of the Invention] A. Industrial Application Field This invention relates to a device that uses a pulse motor (including a so-called stepping motor) to position an object such as a stage with high precision. .

B. Prior Art This type of positioning device uses a pulse motor to rotate, for example, a threaded rod, and uses a screw feed mechanism to move a stage in a straight line, and positions the stage at a target position while feedback controlling the pulse motor.

In this case, consider the travel distance per pulse in advance, convert the travel distance to the target position for stage positioning into the number of pulses, and compare this set value with the number of pulses corresponding to the current stage position. Positioning is performed using feedback control while driving the pulse motor at acceleration, constant speed, and deceleration. The constant speed drive of the pulse motor in this case performs what is called high speed operation.

This positioning method is illustrated in Figure 5.
Pulse motor drive control is as shown in the flowchart of FIG.

Problems to be Solved by the C0 Invention The conventional positioning method has the following problems. That is, it is necessary to convert the distance from the current position of the stage to the positioning target position into the number of pulses in advance. Since the timing and position information are not fed back to the control, even if the pulse motor loses synchronization, it may not be detected. Furthermore, since positioning is performed in high-speed operation mode, accuracy cannot be improved due to overshooting, etc. Therefore, when operating at low speed, it takes a long time and promptness deteriorates.

A positioning device provided by the present invention includes means for setting a predetermined distance in front of the target position from the distance from the current position of an object to the target position, and a means for setting a predetermined distance in front of the target position, the distance being smaller than the predetermined distance. means for setting a fixed distance before the target position; a pulse generator for switchably generating high-speed operation pulses and low-speed operation pulses; It is provided with a pulse motor drive means that drives the motor at a constant speed using a driving pulse, decelerates the motor when a predetermined distance is reached, and further drives the motor at a constant speed using a low-speed driving pulse when the predetermined distance is reached.

60 Effect If the distance from the current position to the target position is long, high-speed operation is performed; if the distance is short, high-speed operation is not performed, and deceleration operation is started at a predetermined distance position. The pulse motor is driven by a low-speed driving pulse for a certain distance to the target position, and the object slowly reaches the target position.

F. Embodiments Hereinafter, the structure and operation of the present invention will be explained according to embodiments shown in the drawings from FIG. 1 to FIG. 4.

FIG. 1 is a block diagram schematically showing the configuration of a pulse motor type positioning device according to the present invention, in which 1 is a pulse motor, 2 is a pulse motor driver, and 3 is a pulse motor controller. Reference numeral 4 denotes a stage, and the pulse motor 1 is mechanically connected to the stage 4 by, for example, a screw feed tlltlI, as described above.

That is, a threaded rod (not shown) rotated by the pulse motor 1 is screwed into the stage 4m, so that the stage 4 moves in the left-right direction as shown in the figure in response to the rotation of the pulse motor 1.

5 is a sensor that detects the movement of stage 4, for example
A rotary encoder that measures the rotation of a threaded rod or a linear encoder that converts the amount of displacement of the stage into a digital signal is used. The signal from this sensor 5 is BC
It is output as a D (Binary Coded Decimal) signal and input to the latch circuit 6 of the pulse motor controller 3.

On the other hand, 12 is a pulse generator that outputs high-speed operation pulses and low-speed operation pulses by arbitrarily switching between them.
The signal is inputted to the pulse motor driver 2 via the pulse motor driver 2, and the pulse motor 1 is operated at high speed or low speed, and further accelerated or decelerated. 10 is an oscillation circuit.

The pulse motor controller 3 further includes an arithmetic circuit 13.
A setting switch 9 is also installed. This setting switch 9 is provided with a target position setting switch, a slow stop switch, other switches, etc., and is further provided with a group of keys for inputting desired values. Therefore, for example, the target position (X in FIGS. 2 and 3)
, ), input the desired value using the key, and then press the target position setting switch.The target position is digitally displayed at this switch and output, and the counter circuit 8 is input. Next, when inputting the slow stop position (X in Figures 2 and 3), input the desired value Xs in the same way using the keys, and then press the slow stop position switch.
Then, the value is digitally displayed at the switch, output, and input to the counter circuit 8. The counter circuit 8 determines at what point the pulse motor 1 is slowed down, that is, decelerated, based on these input values, that is, X. -X/) position. When the target position is relatively short as shown in FIG. 3, the predetermined distance until the start of deceleration is x, x,
You can't take enough for 1, so X, -Xs /2
In this case, stage 4 does not reach the maximum speed, and deceleration is performed immediately during acceleration.The counter circuit determines the deceleration start position, that is, a predetermined position ahead of the target position. is automatically calculated and input to the comparator 7. The comparator 7 compares the current position signal stored and held in the latch circuit N6 with the signal set in the counter circuit 8, and inputs the comparison output to the control circuit 11 as so-called feedback control. The pulse motor driver 3 is appropriately inputted and controlled by the full step pulse signal from the pulse motor 1 to drive the pulse motor 1 at an accelerated speed or at a high speed (constant speed).

When the stage 4 moves a predetermined amount by such controlled driving and reaches a certain distance in front of the target position, the comparator 7 detects this and changes the pulse generation of the pulse generator 12 to low-speed operation pulse generation via the control circuit 11. Outputs a command signal to switch to

This command signal causes the pulse generator 12 to output a low-speed operation pulse from now on, thereby switching the pulse motor 1 to a slower operation than before.

When the stage 4 moves toward the target position during low-speed operation and reaches within the tolerance range (X, -D), no output is output from the comparator 7 and the pulse motor 1 stops driving. In this case, since the operation is at low speed, the stop is performed reliably and the target position is not exceeded beyond the error range.

The above operation is as shown in the flowchart shown in FIG.

Although the features of the present invention have been described in detail above, the present invention is not limited to the above-mentioned and illustrated examples, but includes various modified embodiments. Although the use of a pulse motor is a prerequisite, the present invention is not limited to a device that moves the stage linearly, but can also be applied as a positioning device using a rotational movement method. The configuration, operating method, setting value display method, etc. of the setting switch for setting the predetermined distance and constant distance from the target position are not limited to the above, and the signal from the senna is not limited to the BCD signal. It is also possible to use a pulse motor driver having a microstep function that divides one step into a low-speed operation mode.

Effects of G, OQ Light The pulse motor type positioning device provided by this invention is as detailed above, so if the predetermined distance from the target position is appropriately set, the accuracy can be achieved regardless of the maximum speed, acceleration/deceleration rate, and initial speed. Good positioning is possible and positioning time can be shortened.

For example, the sensor has a resolution of 0.1/4 m and an initial velocity of 157 m.
074m/s, maximum speed 3140/4131/s, low operating speed 15. As a result of experimenting with setting to im/s,
The accuracy of the conventional method is 1107a, 0.1 Hm.
Accuracy was obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing the configuration of the present invention, Figs. 2 and 3 are explanatory diagrams of the operation of the invention, Fig. 4 is a flowchart diagram related to the invention, and Fig. 5 is an operation diagram of the conventional device. , 6th
The figure is a flowchart diagram. l...Pulse motor, 2...Pulse motor driver 3...Pulse motor controller, 4...Stage, 5...Sensor, 7...Comparator, 8...Counter circuit, 9... ...Setting switch, 11...Control circuit, 12...Pulse generator, 13...Arithmetic circuit collar 6th factor t1

Claims (1)

[Claims] (1) In a device that rotates and drives a pulse motor to position an object at a target position, means for setting a predetermined distance ahead of the target position from the distance from the current position of the object to the target position, and a value smaller than the predetermined distance. means for setting a fixed distance before the target position; pulse generating means for generating a large step pulse and a small step pulse in a switchable manner; and accelerating a pulse motor until the object reaches the predetermined distance. and a pulse motor drive means for driving at a constant speed using large step pulses, decelerating driving when a predetermined distance is reached, and further driving at a constant speed using small step pulses when the predetermined distance is reached. .