JPH07121237A - Friction drive - Google Patents

Abstract

PURPOSE:To offer the friction driving device which is improved in positioning response by controlling the driving of a motor so that a slip caused between the driving shaft of the motor and a member to be positioned becomes small. CONSTITUTION:A rotary encoder 7 measures the angle of rotation of the driving shaft of the motor 1 and a length measuring instrument 5 measures the output of a friction driving unit 13, i.e., the current position of the member to be positioned. A slip calculator 12 calculates a slip quantity from the measured angle of rotation of the driving shaft and current position information, and the rotating speed of the driving shaft of the motor 1 is corrected on the basis of this slip quantity. Consequently, the motor 1 can be driven and controlled so that the slip becomes small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction drive device for detecting the slippage between a drive shaft of a motor and a member to be positioned and controlling the drive of the motor so as to reduce the slippage.

[0002]

2. Description of the Related Art Conventionally, in a friction drive device of this type, the position of a member to be positioned (hereinafter referred to as a rod) driven by a drive shaft of a motor is measured by a length measuring device, and this rod position information is obtained. The rod is positioned by controlling the drive of the motor based on the above. More specifically, referring to FIG. 5, the position command value is input to the motor 1 via the compensating element 11 to rotate the motor 1, and the drive shaft of the motor 1 causes a friction drive unit (Friction Drive Unit). Below FD
The rod of 13) is driven and positioned.
At this time, the length measuring device 5 measures the position of the rod of the FDU 13, and the position information of this rod is fed back to the compensating element 11 to correct the rotational speed of the drive shaft of the motor 1.

[0003]

However, even if a slip occurs between the drive shaft of the motor and the rod, the slip is not detected and the control is not corrected, so that an overrun may occur. As a result, there is a problem in that positioning responsiveness is poor and positioning settling takes time.

The present invention has been made in order to solve the above-mentioned problems, and the positioning response is achieved by driving and positioning the motor so that the slip generated between the drive shaft and the positioned member is reduced. It is an object of the present invention to provide a friction drive device that improves the performance and shortens the settling time.

[0005]

In order to achieve the above object, the present invention provides a friction drive unit having a positioned member driven by a drive shaft of a motor, and position measuring means for measuring the position of the positioned member. A friction drive device that positions the member to be positioned by driving and controlling the motor based on the position information of the member to be positioned measured by the position measuring means. From the rotation angle measuring means for measuring the angle, the rotation angle of the drive shaft measured by the rotation angle measuring means, and the position information of the positioned member measured by the position measuring means, the drive shaft and the positioned member And a rotation speed of the drive shaft of the motor based on the slip amount calculated by the calculation means. In which it was to make a correction to.

[0006]

According to the above construction, the rotation angle measuring means measures the rotation angle of the drive shaft of the motor, and the position measuring means measures the position of the member to be positioned. From the measured rotation angle of the drive shaft and the position information of the member to be positioned, the calculating means calculates the slip amount generated between the drive shaft and the member to be positioned, and the rotation of the drive shaft of the motor based on this slip amount. The speed is corrected. As a result, the motor is drive-controlled so that the slip is reduced, and the positioning of the positioned member is performed with good responsiveness.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic structure of a friction drive device. The present apparatus includes a motor 1 that is a drive source and a motor 1
Rod 3, which is a member to be positioned, which is driven by the drive shaft 2 of the support roller 4, a support roller 4 for movably supporting the rod 3, a laser length measuring device 5 and a laser mirror 6 for measuring the position of the rod 3, and a motor. The rotary encoder 7 is attached to the first drive shaft 2 and measures the rotation angle of the drive shaft 2. The laser mirror 6 is provided on the side end surface of the rod 3, and the laser length measuring device 5 is arranged at a position facing the laser mirror 6. The laser length measuring device 5 irradiates the laser on the laser mirror 6, receives the laser reflected by the laser mirror 6, and determines the position of the rod 3 with the laser wavelength as the resolution using the interference of the laser waves, for example. taking measurement.

As means for measuring the position of the rod 3,
The present invention is not limited to the laser length measuring device 5 and the laser mirror 6 described above, and various modifications are possible. For example, as shown in FIG.
A capacitance type displacement gauge 15 that detects displacement by measuring capacitance may be used, or a linear encoder 25 may be used as shown in FIG.

FIG. 4 shows a friction drive device, in particular its servo system. In this servo system, the compensating element 11 is for making the control respond stably and quickly, and in general, a proportional element, an integral element, a derivative element, a phase lead element and a phase delay element are used. The motor 1 is driven and controlled by receiving a signal from the compensation element 11. Friction drive unit (FDU) 13
Is a rod 3 frictionally driven by the drive shaft 2 of the motor 1.
Have. The length measuring device 5 measures the output of the FDU 13, that is, the current position of the rod 3, and feeds it back to the compensating element 11. The rotary encoder 7 measures the rotation angle of the drive shaft 2 of the motor 1. The slip calculator 12 calculates the amount of slip generated in the FDU 13 based on the measured outputs of the rotary encoder 7 and the length measuring device 5. The compensating element 21 corrects the output of the compensating element 11 based on the output from the slip calculator 12.

The operation of the servo system having the above configuration will be described. By giving a predetermined position command to the compensation element 11,
The compensating element 11 outputs a rotation speed command to the motor 1, and the motor 1 is driven accordingly. The rotation angle of the motor 1 (driving shaft 2) at that time is measured by the rotary encoder 7, and the output of the FDU 13, that is, the current position of the rod 3 is measured by the length measuring device 5. The rotation angle of the motor 1 (driving shaft 2) by the rotary encoder 7 is input to the slip calculator 12. The current position information measured by the length measuring device 5 is fed back to the compensating element 11 and input to the slip calculator 12. In the slip calculator 12, the rotation angle θ of the drive shaft 2 and the rod 3
From the current position information x, the slip amount S generated between the drive shaft 2 and the rod 3 is calculated by the following equation (1). S = x−πD × θ / 360 (1) However, the diameter of the drive shaft 2 is D.

The compensating element 21 optimally controls the rotation speed command for the motor 1 based on the slip amount S obtained above. That is, when the slip amount S is large, the rotational speed command is greatly decelerated, and when the slip amount S is small,
Decelerate the rotation speed command slightly. In this way, since the rotation speed of the motor 1 is corrected based on the slip amount S, the speed of the motor is controlled so as to reduce the slip generated between the drive shaft 2 and the rod 3, and as a result, the FDU
The output of No. 13, that is, the positioning response of the positioned member is improved, and the settling time can be shortened.

[0012]

As described above, according to the present invention, from the rotation angle of the drive shaft of the motor and the position information of the positioned member driven by the drive shaft, the slip amount generated between them is calculated, Since the rotation speed of the motor drive shaft is corrected based on the amount of slip, it is possible to drive and control the motor so that the slip becomes smaller, thus improving the positioning response and shortening the settling time. can do.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a friction drive device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of a friction drive device according to a modification.

FIG. 3 is a perspective view showing a schematic configuration of a friction drive device according to another modification.

FIG. 4 is a block diagram showing a friction drive device and a servo system thereof according to the present embodiment.

FIG. 5 is a block diagram showing a conventional friction drive device and its servo system.

[Explanation of symbols]

 1 Motor 2 Drive Shaft 3 Rod 5 Laser Length Measuring Device 6 Laser Mirror 7 Rotary Encoder 12 Slip Calculator 13 Friction Drive Unit 15 Capacitance Displacement Meter 25 Linear Encoder

Claims (1)

[Claims] 1. A friction drive unit having a member to be positioned which is driven by a drive shaft of a motor, and position measuring means for measuring the position of the member to be positioned, and the position to be measured measured by the position measuring means. In a friction drive device for positioning the member to be positioned by controlling the drive of the motor based on position information of the member, a rotation angle measuring means for measuring a rotation angle of a drive shaft of the motor, and the rotation angle measuring means. The rotation angle of the drive shaft measured by and the position information of the positioned member measured by the position measuring means, and a calculating means for calculating the slip amount generated between the drive shaft and the positioned member, A friction drive characterized in that the rotation speed of the drive shaft of the motor is corrected based on the slip amount calculated by the calculation means. Moving device.