JPS63251810A - Correcting device for horizontal multi-joint robot - Google Patents

Abstract

PURPOSE:To realize an automatic correction test of a robot by preparing data so that the error of each part can be analyzed in a job where the robot puts its tip pin into a hole. CONSTITUTION:An inserting pin unit 2 attached at the tip of a robot is put into a measurement board 15 having plural bosses showing clearly the hole positions in terms of a three-dimensional way. Thus the hole position data are substituted for measurement of the robot tip coordinates. An inserting pin 20 is not fixed at a robot tip 10a and supported by a renear guide 17 via a spring 19. Thus, no collision is produced between the torque of a motor and its own reaction at a position where insertion of the pin 20 is through. As a result, the pin 20 can be inserted even in such a state where the vertical positioning servo is applied with a Z axis. In such a way, the correction data can be fetched with a perfect automatic operation after a robot is once put on the board 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to industrial robots, and more particularly to a calibration device for a water rate articulated robot.

[Conventional technology]

Recent systems, in which work plans are executed by a host computer and the operational data is sent to a robot controller, are becoming more practical as computers become more sophisticated. However, with only this computer data, the robot will deviate from the target coordinate values. This can be compensated by aligning the robot's coordinate system with the work environment's coordinate system, but it is not perfect.
This is because the actual shape of the robot is not the ideal shape calculated within the robot controller, but is distorted.

Even if the initial shape is mechanically adjusted using a jig when assembling the robot, the arm will still bend. Therefore,
Keep the errors of each part as calibration data.

Methods have been proposed to correct shape errors using software, such as calculating the coordinate value error at the tip of the robot (hereinafter referred to as tip error) from the calibration data and correcting it accordingly.

The case of the robot shown in FIG. 4 is shown below.

P+ΔP=Rot, +asi [Rotm+as (R
ot#+A@1 (z◆ΔZ)+L, +ΔL,)+L1
+ΔL,]◆ΔB÷Δ◎ (G)
Here, P: Target coordinate value ΔP: Leading error Rot@1: ■Rotation conversion (main axis) Δ■l: Swing rotation axis origin error and joint axis inclination (main axis) Z: Robot Z axis ^Z: Tool Installation error Ll: Arm length (i-th arm) M Ll: Arm length error (i-th arm) ΔB = Installation error Δ(■): The deflection type at the tip in a certain posture ■ is the This is a formula for calculating the tip error ΔP, and is a method of shifting the target value by the tip error to obtain a temporary target value P'. That is.

p' = p - ΔP -■ This method calculates the difference between each member ΔE (Mu, Todoroki Z, ALL, AB
, Δ(■), etc.), it is possible to calibrate with high accuracy.

Therefore, it is sufficient to measure calibration data for each member difference for each robot. Since it is time-consuming to calculate each member difference directly, it is convenient to solve the unknown quantity (each member difference) included on the right side by measuring the tip coordinate P + ΔP using 20). If the unknown quantity (difference between each member) included in the right-hand side is minute, −th order approximation expansion can be performed, so it becomes a simple simultaneous −th order equation. However, since the number of equations is small relative to the unknown quantity, the tip coordinates P+AP must be set at multiple points. Ni〇 is a first-order approximation expansion of Ni〇.

ΔP−Δ(■)=[A(■)koΔE■
Here, [A(■)]: When measuring the tip coordinate of the error influence matrix regarding posture Φ, when analyzing the difference ΔE of each member from equation (■) including arm deflection and axis inclination, measurement in the Z-axis direction is also required. It was important.

[Problem that the invention seeks to solve]

When measuring the tip coordinates including the Z-axis direction, there is a simple method of simply measuring the minute error ΔP in the Z direction.

This can be done quickly with relatively simple equipment, but the slope cannot be analyzed.

If the error in the Z-axis inclination cannot be ignored, it is necessary to move the robot tip up and down and measure the coordinate values within the XY plane. This is a three-dimensional measurement, but non-contact three-dimensional measurement has poor accuracy, so a contact method is required and the operation is troublesome.

An object of the present invention is to obtain a calibration device for a horizontal articulated robot that can simplify the measurement of robot tip coordinates. By inserting the insertion pin unit 2 there, the hole position data can be used as a substitute for measuring the robot tip coordinates.

(Function) Once the tip of the robot is measured, the robot itself can do the work by inserting the pin unit at the tip into the hole.

〔Example〕

(Configuration of Example) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, an insertion pin unit 2 to be attached to the Z-axis at the tip of the robot during calibration, a robot lO to be calibrated,
The robot controller 11, and the Z-direction minute error measuring device main body 12 that takes in information from the insertion pin unit 2 via a cable when insertion is completed.

The cable hanging column 13, the analysis device 14 that exchanges information via the cable between the robot controller 11 and the Z-direction minute error measuring instrument body 12, and the target robot IO are fixed during calibration, and the insertion pin unit 2 is positioned. It consists of a measuring table 15 in which a plurality of holes are three-dimensionally measured in advance and have bosses with opening surfaces of different heights. In FIG. 2 showing the detailed configuration of the insertion pin unit 2, an A block 16 is attached to the robot tip 10a, a glue near guide 17 with a stopper is attached to the A block 16, and the A block 16 is supported by the glue near guide 17. a spring 19 between the A block 16 and the B block 18, an insertion pin 20 with a tapered end attached to the B block 18, and a near guide 17 attached to the B block 18 and attached to the A block 16. It consists of a two-directional minute error measuring device 21 (for example, a dial gauge) for measuring relative distances in directions.

(Operations of the Embodiment) The flow of work for inserting the insertion pin unit 2 attached to the robot tip 10a into the hole of the measuring table 15 will be explained below with reference to FIG.

First, the robot tip 10a is moved above the hole based on the hole position data of the measuring table 15. Even if the moving position deviates from the actual hole position, set the motor torque of the first and second axes of the robot in a state where no torque is applied (servo free), lower the robot tip 10a, and insert the tapered insertion pin 20 into the hole. and insert it. The robot tip 10a is connected to the pin reference surface 20.
Even when a hits the opening surface of the hole, it is further lowered, and the Z-direction minute error measuring device 21 calculates the shortening length of the relative distance between the height of the robot tip 10a and the height of the opening surface of the hole from the relative distance between the A block 16 and the B block 18. To measure the movement, set the movement target values in two directions downward in advance. After the robot tip is positioned, the robot controller II can set the movement target values for the robot's 1st, 2nd, and 2nd axes (rotation, up and down). The current value is read into the analysis device 14 in the vertical direction of the Z-axis, and the current value is a value corrected by the shortening of the reading of the Z-direction minute error measuring device 21. This insertion work is repeated for multiple holes to increase the number of equations 20 to greater than the unknown (each part error ΔE).The equations 20 are three for X, Y, and Z when measuring one hole.

The value to be substituted for 2〇 is 9. Just insert the pin into 6 whose position is clear, and the three-dimensional coordinate value of the hole will be the robot tip coordinate P + M P
And, the target coordinate value P (actually, the current coordinate value in the calculation because it is not the target and has been corrected by the hole) is calculated from the posture value at the time of insertion in the robot controller II. Since it can be calculated, AP is the difference. Solve 20 to calculate the error ΔE for each part, and save this value as calibration data specific to the robot measured here, along with the environmental conditions (temperature, etc.) at the time of measurement.

(Effects of Example) The insertion pin 20 is not fixed to the robot tip 10a, but is supported by the linear guide 17, and the spring 19 is used.

Since the motor's torque does not conflict with its own reaction force at the insertion completion position, insertion is possible even with the Z-axis up and down positioning servos turned on. As a result, when the robot is placed on the measurement stand 15, calibration data can be taken in completely automatically. In addition, if the insertion pin 20 is removable and made of a low-friction Teflon material with a small gap, the influence of looseness in the robot tip coordinates can be eliminated, and the measuring table 15 will not wear out, resulting in a long service life.

〔Effect of the invention〕

As the robot inserts the tip of the pin into the hole, data is collected that can be used to analyze errors in each part, making it possible to perform calibration tests automatically.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the horizontal articulated robot calibration device of the present invention, FIG. 2 is a detailed view of the main part of FIG. 1, and FIG.
This figure is a flowchart when measuring with the apparatus shown in FIG. 1, and FIG. 4 is a perspective view showing the configuration of a robot related to the present invention. 10...Horizontal articulated robot 11...Robot controller 14...Analyzer 12...Z-direction minute error measuring instrument body 15...Measuring table 16...A block 18...B block 19 ... Spring 17 ... Linear guide 21 ... Z-direction minute error measuring device 20 ... Insertion pin 10a ... Robot tip agent Patent attorney Noriyuki Chika -1

Claims (1)

[Claims] A block attached to the Z-axis at the tip of the horizontally articulated robot,
The block includes a pin freely supported only in the vertical direction, a measuring means for measuring the relative distance between the robot tip and the pin, and an elastic body that generates a reaction force in relation to the relative distance between the robot tip and the pin. and a measuring table on which the robot is installed and has a plurality of holes for the pins to be inserted, including ones with different opening heights; A calibration device for a horizontal articulated robot, comprising an analysis device that reads values and performs arithmetic processing.