JP2000039920A - Multiaxial position controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the multiaxial controller having simple constitution which uses one servomotor. SOLUTION: This controller is equipped with a hydraulic pump 10 which is so controlled by the servomotor 13 as to discharge and suck hydraulic oil, (n), e.g. three hydraulic cylinders 20, 20a and 20b which are driven forward by being supplied with the hydraulic oil so as to control the positions of (n) (n: integer larger than 2) driving mechanisms for control axes and return to their origin positions through the discharging of the hydraulic oil, (n-1), e.g. 2 hydraulic valves 30 and 30a which cut off the supply of the hydraulic oil to the hydraulic cylinders 20 and 20a except the 3rd hydraulic cylinder 20b achieving forward movement to a target position by responding to detection signals of position sensors 26 and 26a attached to the hydraulic cylinder 20 and 20a and detecting the achievement of the forward movement to the target position. The servomotor 13 stops the discharging operation in response to the detection signal of a position sensor 26b attached to the 3rd hydraulic cylinder 20b and detecting the achievement of the forward movement to the target position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-axis position control device for controlling a plurality of drive mechanisms attached to a controlled object from an original position to a target position.

[0002]

2. Description of the Related Art FIG. 2 shows a multi-axis position control device of this type. For example, in a manufacturing process of an automobile, a flange portion thereof is positioned with respect to a receiving piece 2 so as to position and clamp a work 1. The clamp device 4A, which opens and closes the clamp piece 3 with the air cylinder 4, is connected to the three
The position is controlled in the directions of the control axes.

[0003] This clamping device has a slider 6 to which the device is attached and which slides left and right as viewed in the figure.
A three-axis control mechanism comprising: an elevating slider 6a that guides the slider slidably to move up and down; and a slider 6b that guides the slider to move up and down and slides by being guided by the base 6c in the depth direction. Prepared as
Servo motors 7 to 7b for slidingly driving the respective components, rotary encoders 8 to 8b for detecting the rotational position of the associated servo motor, and a motor control circuit for moving the associated motor between the target position and the original position in response to the detection signal. 9
9b are attached.

[0004]

As a result, the clamping device 4A can clamp the work 1 in a state where the position thereof is controlled in the direction of each control axis and the work 1 is positioned, but the servo motors 7 to 7b are controlled for each control axis. Required, resulting in higher costs as the number of axes increases.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a multi-axis position control device capable of controlling the position of a control mechanism with a simple configuration using one servomotor.

[0006]

In order to achieve the above object, according to the present invention, according to claim 1, a plurality of drive mechanisms in a control axis direction attached to a controlled object are respectively controlled from an original position to a target position. In such a multi-axis position control device, a hydraulic pump controlled to perform discharge and suction of hydraulic oil by a servomotor and a drive mechanism for n (n is an integer of 2 or more) control axes are provided. Each of the n hydraulic cylinders driven forward by supply of hydraulic oil for position control, and returned to the original position by discharge of hydraulic oil, and the nth hydraulic cylinder that finally achieves forward movement to the target position By responding to a detection signal of a position sensor attached to each of the excluded n-1 hydraulic cylinders and detecting that the forward movement to the target position has been achieved, And n-1 hydraulic valves for shutting off the supply of pressurized oil, and a detection signal of a position sensor attached to the n-th hydraulic cylinder for detecting that the forward movement to the target position has been achieved. The discharge operation is stopped in response to

[0007] With the discharge of the hydraulic pump, the hydraulic cylinder is supplied with hydraulic oil through an opened hydraulic valve and is driven forward. When the position sensor detects the achievement of the forward movement of the associated hydraulic cylinder to the target position, the associated hydraulic valve shuts off the supply of hydraulic oil. Finally, when the position sensor of the hydraulic cylinder reaching the target position detects the advance to the target position, the discharge of the hydraulic pump stops. When the control mechanism returns, the servomotor causes the piston or the plunger to return to the original position or reverses the rotation of the rotor by a predetermined amount to cause the hydraulic pump to perform a predetermined amount of suction. At this time, when the hydraulic oil in the hydraulic cylinder is discharged through the opened hydraulic valve, the control mechanism is moved back by the spring being biased or the hydraulic cylinder being moved back by the hydraulic control from the outlet side. According to the second aspect of the present invention, when the hydraulic pump stops discharging, the hydraulic cylinder that finally reaches the target position reaches the target position.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-axis position control device according to an embodiment of the present invention will be described with reference to FIG. This control device drives and controls the sliders 6, 6a and 6b as a control mechanism of the above-described clamping device 4A. Is driven forward by the supply of hydraulic oil, and returns to its original position when it is discharged.
Two hydraulic cylinders 20, 20a, 20b and two hydraulic cylinders 20, except for a third hydraulic cylinder 20b, which finally reaches the target position due to a long forward stroke.
Two hydraulic valves 30 attached to each of the hydraulic cylinders 20 and 20a for shutting off the supply of hydraulic oil to the associated hydraulic cylinders 20 and 20a in response to detection signals of position sensors 26 and 26a for detecting a forward movement to a target position; 30a. Further, the third hydraulic cylinder 20b is also provided with a position sensor 26b for detecting the forward movement to the target position in order to control the discharge amount of the servo motor 13.

The hydraulic pump 10 is configured to perform a discharge and a suction by moving the piston 11 forward and backward by a ball screw 12 rotated and driven by a servomotor 13. The motor control circuit 14 drives the piston 11 forward or backward toward the original position or a set value corresponding to the maximum discharge amount in response to a detection signal of an encoder 15 serving as a discharge amount sensor for detecting the rotational position of the servo motor 13. During forward movement, before reaching the set value corresponding to the maximum discharge amount, the forward movement is stopped in response to the detection signal of the position sensor 26b.

When hydraulic oil is supplied to the cylinder chambers 21 to 21b of the hydraulic cylinders 20 to 20b, the cylinder rods 23 to 23b projecting from the pistons 22 to 22b move forward to move the sliders 6 to 6b. Drive. Further, when the hydraulic oil is discharged from the cylinder chambers 21 to 21b during the suction operation of the hydraulic pump 10, the hydraulic oil 10 is returned to the original position by the bias of the compressed spring 24. Valve control circuits 35, 35a which normally open the hydraulic valves 30, 30a and close when the position sensors 26, 26a provided on the peripheral wall of the associated cylinder detect that the pistons 22, 22a reach the target position. Are each included.

The operation of the thus-configured multi-axis position control device is as follows. In the normal state, the piston 11 of the hydraulic pump 10 occupies the original position, and the hydraulic valves 30, 30
When a is opened, the pistons 22 to 22b of the hydraulic cylinders 20 to 20b also occupy the original positions. Thus, the sliders 6 to 6b are waiting at the original position.

When the work 1 is carried into the work place and an operation start signal is input from the control panel, the motor control circuit 14 causes the piston 11 to advance toward the maximum target position to discharge hydraulic oil. Along with the supply of the hydraulic pressure, the pistons 22 to 22b of the hydraulic cylinders 20 to 20b respond and drive the sliders 6 to 6b forward. In the process, when the position sensors 26, 26a detect that the associated pistons 22, 22a have reached the target positions, the associated hydraulic valves 30, 3,
The sliders 6 and 6a are position-controlled to the target positions by closing 0a and shutting off the supply of the hydraulic oil. Subsequently, when the position sensor 26b detects the arrival at the target position, the hydraulic pump 10 stops discharging, and the position of the slider 6b is also controlled to the target position.

When the work after the positioning and clamping of the work 1 is completed, an original position return signal is input from the control panel, the hydraulic valves 30 and 30a are opened, and the hydraulic pump 1 is opened.
0 performs suction and returns to the original position,
20b returns to the original position by the bias of the spring 24, and the sliders 6 to 6b return to the original position.

In the motor control circuit 14, the position sensor 26b is omitted and the output value of the encoder 15 corresponds to the discharge amount at which the third hydraulic cylinder 20b achieves the target position, instead of the above-described embodiment. The discharge operation may be stopped when the set value is matched. Further, instead of the encoder 15, a sensor for detecting the actual position of the piston 11 of the hydraulic pump 10 may be provided as a discharge amount sensor on the cylinder peripheral wall. The hydraulic pump can be of a rotary type instead of a piston type.

The hydraulic cylinder may use a pneumatic pressure at its outlet using a return cylinder instead of a single-acting hydraulic cylinder. The present invention is not limited to the slider type, but is similarly applied to a control mechanism that converts a linear drive of a hydraulic cylinder into a rotary drive, and is also applied to a common hydraulic pump with a servo motor even when the number of control axes further increases. Position control is possible.

[0016]

As described above, according to the present invention, by controlling the position of the associated control mechanism using a plurality of hydraulic cylinders driven by a double-acting hydraulic pump controlled by a servomotor, an inexpensive multi-axis Is realized. Even if the number of shafts increases, the structure does not need to be bulky.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a multi-axis position control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a conventional multi-axis position control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hydraulic pump 11, 22-22b Piston 13 Servo motor 20-20b Hydraulic cylinder 26-26b Position sensor 30, 30a Hydraulic valve

Claims (3)

[Claims] 1. A multi-axis position control device which controls a plurality of drive mechanisms in a plurality of control axis directions attached to a controlled object from an original position to a target position, wherein a servo motor discharges and sucks hydraulic oil. (N is an integer of 2 or more)
N hydraulic cylinders which are driven forward by the supply of the hydraulic oil to control the positions of the drive mechanisms for the respective control axes, and which return to the original positions by discharging the hydraulic oil; Responding to a detection signal of a position sensor attached to each of the n-1 hydraulic cylinders except for the n-th hydraulic cylinder for achieving the forward operation and detecting that the forward operation to the target position has been achieved. And (n-1) hydraulic valves for shutting off the supply of the hydraulic oil to the associated hydraulic cylinder, wherein the servo motor is attached to the n-th hydraulic cylinder and moves forward to a target position. A multi-axis position control device, wherein a discharge operation is stopped in response to a detection signal of a position sensor that detects that the position is achieved. 2. Instead of the servo motor responding to a detection signal of a position sensor attached to the n-th hydraulic cylinder,
2. The multi-axis position control device according to claim 1, wherein the discharge operation is stopped in response to a detection signal of a discharge amount sensor attached to the hydraulic motor for detecting a predetermined amount of discharge. 3. The multi-axis position control device according to claim 1, wherein the hydraulic cylinder is a single-acting type that automatically returns to an original position by a spring force when the hydraulic oil is discharged.