JPS628206A - Industrial robot control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a control device for an industrial robot.

BACKGROUND OF THE INVENTION There are various methods for determining the origin position of a joint of an industrial robot. One method is to provide a limit switch near the origin of the robot joint, and after the limit switch is activated, zero pulses are detected from an incremental encoder attached to a motor that drives the robot joint. Another method is to attach an absolute encoder to a motor that drives a robot joint to determine the origin of the robot joint.

Problems to be Solved by the Invention However, in the former case, when changing the robot origin, it is necessary to change the mounting position of the limit switch and redefine the origin position accurately, which is not easy to do and operate.

Furthermore, in the latter case, there are drawbacks such as the absolute encoder having low resolution and being expensive.

The present invention aims to provide a control device for an industrial robot that can accurately determine the origin of a robot joint using an inexpensive potentiometer that indicates absolute position and an incremental encoder with excellent resolution.

Means for Solving the Problems In order to achieve the above object, the present invention provides a programmable manipulator having a plurality of arms with potentiometers for generating a voltage output proportional to the joint angle at the joints, and for driving the joints. An incremental encoder that outputs a reference signal every rotation of the motor shaft is provided on the motor shaft, and the output voltage values of the potentiometer corresponding to the reference signal of the incremental encoder are sequentially numbered over the entire operating angle of the joint. A memory means for memorizing,
an analog/digital conversion means for converting the output voltage value of the potentiometer into a digital value with respect to a reference signal of the incremental encoder of the joint; and an output voltage value of the potentiometer converted into a digital value and a numbered output voltage in the storage means. A detection means that sequentially compares the values and detects the neighboring values, and the number of pulses from the origin of the joint is determined by the number of the detected neighboring values using the following formula % formula % Z: voltage of the first potentiometer in the storage means Number of pulses from the origin of the arm position that outputs the value, Q: Number of pulses from the origin of the arm position that outputs the voltage value of the zeroth potentiometer in the storage means, ! = the number of the output voltage value of the numbered potentiometer in the storage means, P: the resolution pulse number of one revolution of the incremental encoder, It is.

Operation: By the above means, the motor is stopped at the position where the reference signal of the incremental encoder is output, and the voltages of the potentiometers attached to the joints are sequentially stored in the storage means with numbers assigned in advance. When determining the origin of the joint, after detecting the zero pulse signal of the incremental encoder, the motor is stopped, and the output voltage value of the potentiometer and the voltage value of the numbered potentiometers in the storage means are sequentially changed until an approximately equal value is found. Compare them, and if there are approximately equal values, put that number into the above formula and calculate to determine the origin of the joint.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, 1 is an articulated manipulator, 2 is a motor that drives the joints of manipulator 1, 3 is an incremental encoder that accurately detects the rotation angle of the joints of manipulator 1, 4 is a potentiometer, and 6 is a motor for driving the joints of manipulator 1. An analog/digital converter (hereinafter referred to as an A/D converter) that converts an output voltage value into a digital value; This is a control device that controls the motor 2 to be driven.

In the above configuration, the control device 6 moves the joints of the manipulator 1 at a constant speed from the lower limit to the upper limit or from the upper limit to the lower limit of the joint motion range of the manipulator 1, and the incremental encoder attached to the joint of the manipulator 1 moves the joints of the manipulator 1 at a constant speed. After detecting the reference signal No. 3, a stop signal is sent from the control device 6 to the motor 2 to stop the joints of the manipulator 1. The output voltage value of the potentiometer 4 at this time is converted into a digital value by the A/D converter 6, and sequentially stored in a storage means in the control device θ with a number.

When determining the origin of the joints of the manipulator 1, the output voltage value of the potentiometer 4 at the single signal detection position of the 30 incremental encoders is converted into a digital value and stored in the control device 6 over the entire range of motion of the joint of the manipulator 1. At the same speed, the control device 6 moves the manipulator 1 from the joint position until the reference signal of the incremental encoder 3 is detected, and the output voltage value of the potentiometer 4 at that time is converted into a digital value by the A/D converter 6. , the number corresponding to the numbered data stored in the control device 6 is compared, and if it is a nearby value, the number is entered into the following equation and calculated to determine the origin of the joint of the manipulator 1.

Z=Q+1. PZ: the output voltage of the numbered potentiometer stored in the control device 6, the number of pulses from the origin of the joint position of the manipulator that outputs the voltage of the first potentiometer;
Q: Output voltage of the numbered potentiometer stored in the control device 6, number of pulses from the origin of the joint position of the manipulator that outputs the voltage of the zeroth potentiometer, ■ = Number stored in the control device θ The number of the A/D conversion value of the output voltage value of the attached potentiometer; P: resolution pulse number of one rotation of the incremental encoder; FIG. 2 shows the processing by the control device 6.

Effects of the Invention As described above, according to the present invention, the joints of a manipulator having a plurality of arms are determined based on the reference signal of the incremental encoder and the output voltage value of the potentiometer, which are attached to the manipulator so as to change in accordance with the rotation angle of the joints of the manipulator. When determining the origin, highly accurate positioning is possible in an extremely short time and with a small amount of movement. Furthermore, the origin position can be easily changed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a control device for an industrial robot in an embodiment of the present invention, and FIG. 2 is a flowchart of the control device. 1...manipulator, 2...motor, 3...incremental encoder, 4...
... Potentiometer, 6 ... A/D converter, 6 ... Control device. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
--Manihii-7

Claims (1)

[Scope of Claims] A potentiometer that generates a voltage output proportional to the joint angle is provided at the joint of a programmable manipulator having a plurality of arms, and a reference signal is applied to the drive motor shaft of the joint for each rotation of the motor shaft. an incremental encoder for outputting the joint, and storage means for sequentially storing the output voltage values of the potentiometer corresponding to the reference signal of the incremental encoder with numbers over the entire operating angle range of the joint; analog/digital converting means for converting the output voltage value of the potentiometer with respect to a reference signal into a digital value, and sequentially comparing the output voltage value of the potentiometer converted into a digital value with the numbered output voltage in the storage means, The number of pulses from the origin of the joint is determined by the detection means for detecting the value and the number of the detected neighboring value using the following formula Z=Q+I・P Z: Outputs the voltage value of the first potentiometer in the storage means. Number of pulses from the origin of the arm position, Q: Number of pulses from the origin of the arm position that outputs the voltage value of the zeroth potentiometer in the storage means, I: Number of pulses from the origin of the numbered potentiometer in the storage means A control device for an industrial robot, comprising: arithmetic processing means for determining the origin of the joint by performing arithmetic processing with the number P: resolution pulse number of one rotation of an incremental encoder.