JPS61170805A - Industrial robot - Google Patents

Abstract

PURPOSE:To switch speed control steplessly to load control only by one command signal by separating a position control loop from a speed control loop in prior to a command signal of a current control loop. CONSTITUTION:A control device of an industrial robot is constituted of a control part 20 for controlling a motor 100, a position comparing part 21 for finding out the difference between a position command signal P and a position feedback signal Pf obtained from a position sensor 13 through a position counter 30, a speed comparing part 22, a change-over switch 31 for separating the speed control loop from the position control loop, a current comparing part 23, a PWM modulating circuit 25, etc. The position of the robot is counted up by the counter 30, and when the counted value reaches a fixed value, the contact of the leading end part of the robot with a substance to be positioned is detected and the positional shift of the substance to be positioned is detected on the basis of the operation of the fixed counted value and the value of a teaching point. The detected value is corrected by the operation of the teaching point and the size can be also measured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an industrial robot equipped with a function of detecting the position of a workpiece and correcting the position of the workpiece.

BACKGROUND OF THE INVENTION In recent years, industrial robots have been introduced in large quantities as a major tool for making the production process more flexible in high-mix, low-volume production, increasing the flexibility of the production process. These industrial robots, for example, require a positioning device to correctly position the workpiece to be painted at a certain position in the case of a painting robot, and also in the case of assembling electronic parts etc. It is necessary to correctly position the assembly at a certain position.

As these positioning devices, devices that perform positioning in two dimensions are generally used.

The reason why these devices are necessary is that the current industrial mouth robots are called teaching playback robots.
This is because the method of teaching the robot the work points is to teach the necessary points while operating the robot in advance according to the work order, and positioning other than what has been taught cannot be performed. Therefore, in order to have the industrial robot perform work at a position other than the work point taught in advance, while the industrial robot is not working at the work point other than the above,
Alternatively, it is necessary to teach or correct a new work point between the work points.

These devices include, for example, a system that uses a visual recognition device to detect the positional deviation of the painted object or the to-be-assembled object at the work point and corrects the amount of positional deviation, and a method that uses an ultrasonic distance measuring device. A method for recognizing and correcting the position of an object has been proposed.

Generally, the visual recognition device and the ultrasonic distance measuring device are configured by newly added functions to the industrial robot. However, in order to add the above function, it is necessary to equip the industrial robot with an input/output device to connect the above device, and it is also necessary to teach the visual recognition device (object recognition) to perform the above correction in the visual recognition device. Nodame pattern registration) is required.

An example of the above-mentioned conventional position detection and its correction will be described below with reference to the drawings.

FIG. 3 is a schematic diagram of the configuration of a positioning correction method using a conventional visual recognition device. In the figure, 41 is an industrial robot, 42 is a visual recognition device, 43 is a detection camera, 44 is a positioning device, and 46 is an object to be positioned.The operation thereof will be explained below.

The industrial robot 41 is taught its state at the point where the object to be positioned 46 is positioned by the positioning device 44 . If the object to be positioned 46 is not always positioned at a constant position, the coating robot will have uneven coating or uncoated areas, and the assembly robot will be unable to perform fitting work.

However, it is difficult to correctly place the object to be positioned on the positioning device in a manner that prevents misalignment, and it is extremely difficult to manufacture a precise positioning device that can handle high-mix, low-volume production. It is necessary to detect this positional deviation amount by visual recognition and correct it to the correct position using a position correction device.

This has already been made clear (for example, in ``Intelligent Robot'' published by Ohmsha).

Problems to be Solved by the Invention Therefore, in order to correctly position the object to be positioned at the taught position, a precise positioning device or a position correction device has been required, but this has not been done by the robot itself so far. , was highly anticipated.

In view of the above-mentioned problems, the present invention aims to calculate the position of an object to be positioned by calculating the value of a position counter equipped with an industrial robot without using a visual recognition device or an ultrasonic distance measuring device. It is an object of the present invention to provide an industrial robot that can self-correct the position of a positioning object.

Means for Solving the Problems In order to solve the above problems, the industrial robot of the present invention controls the force of the arm using a speed control loop and a current control loop, and changes the position side difference value of the position control loop to the position. The amount of positional deviation of the object to be positioned is detected by a counter, and the amount of positional deviation of the object to be positioned is detected from the industrial robot itself based on the positional deviation value, and the amount of positional deviation is added or subtracted from the value of the teaching point to determine the amount of positional deviation of the object to be positioned. The present invention provides an industrial robot that can perform the above-mentioned painting and assembly by making corrections.

Further, the detected value of the amount of positional deviation can be applied to the dimension measurement of the object to be assembled. An example of the conventional dimension measurement mentioned above will be described below with reference to the drawings.

FIG. 4 is a schematic diagram of a measuring method using a conventional dimension measuring device. In the figure, 50 is a display for Ki method measurement, 51 is a counter, 52 is a light receiving element, 53 is a light source, 54 is a scale slit, 55 is a measuring tip, 56 is a column, and 57 is a 7-liner for raising and lowering the measuring tip.

The operation will be explained below.

When the object 45 to be positioned is positioned by the positioning device 44, the ring 57 is activated to move the moving slit 58 until the probe 55 comes into contact with the object 45 to be positioned.

The moving slit 68 transmits the light emitted from the light source 53 to the light receiving element 52 as bright and dark light. The light receiving element 62 converts the brightness of the light into an electrical signal ωN-0FF, which is input to a counter for counting. The input signal to the counter changes the count in the sibling direction according to the moving direction of the moving slit 58;
To enable switching in the negative direction: Signals with a 90 degree phase difference. The count of the counter 61 is displayed on the dimension display 60 as the amount of movement of the moving slit 58. The dimensions of the object to be positioned 45 can be measured by calculating the amount of movement and the amount of movement of the measuring stylus 65 until it comes into contact with the positioning device 44 .

The dimensions of the object to be positioned can be measured by detecting the measurement as an amount of positional deviation by the industrial robot and calculating the teaching point and the amount of positional deviation of the object to be positioned in the same way as in the measurement of the dimensions.

Function: According to the present invention, detection of positional deviation of a workpiece, correction operation thereof, and dimension measurement can be realized by the configuration shown in FIG. FIG. 2 is a control configuration diagram of the industrial robot 7).

The amount of positional deviation is determined by counting the feedback signal from the position sensor 13 shown in FIG. The contact is detected, and the amount of positional deviation of the object to be positioned 46 is detected by calculating the value of the teaching point and the constant count value. The amount of positional deviation can be correctly corrected by calculation with the value of the teaching point without using the visual recognition device or the like. Further, the dimensions of the object to be positioned can be measured by calculating the teaching point and the amount of positional deviation.

EXAMPLE An industrial robot according to an example of the present invention will be described below with reference to the drawings.

FIG. 1 shows one joint of an industrial robot according to an embodiment of the present invention. In FIG. 1, 10 is an arm in which the joint is configured by a link mechanism, 11 is a holding part for the motor 14, 12 is an encoder scale of the position sensor 13 directly connected to the motor 14, and 15 is the tip of the joint. .

Next, the second section regarding the control device for the industrial robot having the above configuration.
This will be explained using figures. This control device includes a control unit 20 that controls the motor 100, a position command signal P output from the control unit 20, and a position counter 30 that detects the position feedback amount from the position sensor 13 that detects the position of the motor 1oO. A position comparator 21 that takes the difference between the position feed bank signals Pf and a position deviation signal ΔP from the position comparator 21
A speed detector 29 detects the speed based on the speed command signal V of the output signal of the position amplifier Kp and the signal from the position sensor 13 of the motor 10°.
Speed comparator 2 that takes the difference between speed feed puncture signals vfa
2, a current deviation signal generator of the output signal of the speed amplifier Kv that amplifies the speed deviation signal ΔV from the speed comparator 22, and the second output vfa, l! of the speed detector. :, the load command signal β output from the control unit 20 after separating the position control loop and the speed control loop from the point obtained by calculating from the function value of the value of the teaching point and the output vf & of the speed detector are used as the load The load deviation signal α compared by the comparison unit 32, the changeover switch 31 that separates the position control loop into the speed control loop, the signal output from the changeover switch, and the motor 1
Current feedback signal I7. A current comparison section 23 that takes the difference and a current deviation signal Δ from the current comparison section 23
It is composed of a current amplifier Ki that amplifies the current signal I, a PWM modulation circuit 26 that performs pulse width modulation (PWM modulation) on the current signal 24, and a power amplifier 27 for the modulation signal 26.

The operation of the industrial robot control device configured as described above will be explained with reference to FIGS. 1 and 2. First, the control unit 2o outputs the position command signal P according to the value taught to the industrial robot 41. The position command signal P is transmitted to the motor 10.
A position deviation signal ΔP is generated by a position deviation section 21 that takes the difference between the feedback signal from 0 and the position feed bank signal Pf counted by the position counter 30. Position error signal ΔP
is amplified by a position amplifier and becomes a speed command signal V.

The speed command signal ■ is output as a speed deviation signal Δ■ by a speed comparator 22 which takes the difference between the speed feedback signal vf of the speed detector 29 which detects the speed based on the signal from the position sensor 13 of the motor 100, and the speed deviation signal ΔV becomes a current command signal by the speed amplifier Kv. This current command signal works at the contact a of the switch 31 during the position control loop.
However, as the distal end portion 16 of the joint approaches the teaching point, the switching signal S from the control unit 2o is added to the speed control loop, and the contact point is switched to b. b is supplied to the stain flow comparison section 23.

The load command signal point for switching between the position control loop and the speed control loop is calculated according to the following equation.

Teaching point x speed coefficient = position speed loop switching point...
(1) The motor 100 receives the load command signal β and the speed feedback signal V7. In order to add the result to the next stage as the load deviation signal α compared by the load comparator 32, the speed of the tip 16 is controlled from before the object to be positioned 46. When the tip 15 reaches the teaching point, the object to be positioned 1
6, the value of the velocity feedback signal vf& becomes zero, and the load command signal β becomes a current command signal. Therefore, the tip portion 15 switches from conventional speed control to current control and applies a load as a pressing force to the object to be positioned. At this time, the load value can be confirmed by monitoring the current feedback signal Xf, and if the load is insufficient, a desired load can be applied to the object to be positioned 46 by controlling the load command signal β. By checking the value of the position counter when the constant load is applied to the object to be positioned 46, it can be checked whether the object to be positioned 46 is correctly positioned at the teaching point. Through the above inspection, it is possible to inspect dimensions such as positioning errors and height variations of the object to be positioned 45.

Effects of the Invention As described above, the present invention separates the position control loop and the speed control loop before the command signal of the current control loop, and adds the deviation between the speed feedback signal and the load command signal as the current command signal. It is possible to steplessly switch from speed control to load control with a single command signal, making the impact when the tip of the industrial robot makes contact small and constant, and controlling the position and height of the object to be positioned. It can flexibly respond to variations in height.

In addition, the amount of positional deviation when the object to be positioned is pressed in one direction with a constant force can be controlled by measuring in advance the distance between the reference position where the object to be positioned is pressed in one direction and the tip of the industrial robot. By measuring the dimensions of the object to be positioned by calculating the memorized values and the measured dimensions, it is possible to select objects with constant dimensions without using a new dimension measuring device. It is possible to assemble it while

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of one joint of an industrial robot according to an embodiment of the present invention, and Fig. 2 is a diagram showing the configuration of one joint of an industrial robot according to an embodiment of the present invention.
Position command signal, P/... Position feedback batter signal, ΔP... Position deviation signal, Kp song, Position amplifier, ■... Speed command signal, Vl -11a-
...Speed feedback signal, ΔV...
Speed deviation signal, Kv...Speed amplifier, α...
...Load deviation signal, β...Load command signal, S.
...Position speed switching signal, ■...Current command signal, 11 ...Current feedback signal, Δ
I...Current deviation signal, K...Current amplifier, 21...Position comparator, 22...
...Speed comparator, 23...Current comparator, 31.
...Position speed switching section, 32 ... Load comparator, 60 ... Dimension display, 61 ... Counter, 52 ... Light receiving element , 63...
・Light source, 64...Scale slit, 56...
... Measuring element, 56 ... Prop, 57 ...
・Cylinder, 68...Movement slit 0 Agent's name Patent attorney Toshi Nakao and 1 other person 1st
Figure fO-m-Sunku (Lecture 4A4 1f--E-Evening 1 book 12--1. ---Takanakuni

Claims (1)

[Claims] (1) A control system consisting of a position control loop, a speed control loop, and a current control loop, and a force control is performed by the speed control loop and the current control loop, and a position deviation value of the arm and the position control loop is detected. In order to do this, a position counter provided in the control system of the position control loop, a control unit that sends a teaching signal to the arm, and the position deviation value are used to detect whether the arm controlled by the control system has contacted the object to be positioned. Detecting means detects the amount of positional deviation of the object to be positioned from the calculation result of the value of the position counter at the time of contact detection of the object to be positioned when the value of the position counter becomes constant, and detects the position of the object to be positioned. An industrial robot equipped with a correction mechanism that corrects the amount of deviation. 2. In the industrial robot according to claim 1, the correction mechanism that detects the amount of positional deviation and corrects the amount of positional deviation is based on the correction amount of positional deviation and the teaching signal from the control unit to the arm. An industrial robot equipped with a measurement function that measures the key method of the positioning object based on calculation results.