JPS6311292A - Industrial robot - 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 FIELD OF INDUSTRIAL APPLICATION The present invention relates to an industrial robot that corrects deviations in positioning points caused by temperature changes in the industrial robot.

BACKGROUND OF THE INVENTION In recent years, industrial robots are required to have highly accurate positioning when performing work.

An example of the conventional industrial robot mentioned above will be described below with reference to the drawings.

FIG. 6 is an overview diagram of a conventional industrial robot, FIG. 4 is a top view thereof, and FIG. 6 is a schematic explanatory diagram of calculation of positioning points of the conventional industrial robot.

In FIG. 6, 10 is a first arm and 11 is a second arm. 13 is the first arm drive motor, 14 is the second arm drive motor, and 14 is the second arm drive motor.
This is an arm drive motor. 16 is a first arm angle detection encoder, and 16 is a second arm angle detection encoder. 17 is a first arm reduction gear, and 18 is a second arm reduction gear.

Reference numeral 19 denotes an end effector attachment portion, to which a chuck or the like is attached and work is performed. 20 is a control device, 21 is an input cable 7 pull, and 22 is an output cable.

The operation of the industrial robot (K) constructed as described above will be explained below with reference to the drawings.

In FIG. 6, when the coordinate values in the X and Y coordinate system of the end effector mounting portion 19, which is used for positioning and actual work, are input to the control device 2o, the coordinate values are given according to the procedure shown in FIG. An angle θ1 of the first arm 4 and an angle θ2 of the second arm 5 that satisfy the X and Y coordinate values are calculated within the control device.

A command for the movement angle of each axis is transmitted from the control device 20 through the output cable 22 to the first arm drive motor 13 and the second arm drive motor 14 to generate an output. The output of the first arm drive motor 13 is the first arm part reducer 1
7 to the first arm 1°. 1st arm 4
The rotation angle is detected by the first arm angle detection encoder 15 and input to the control device 20 through the input cable 21.

The first arm rotates until the angle detected by the encoder 15 becomes equal to the previously calculated movement angle.

The second arm 11 also rotates in the same manner as the first arm to position the end effector mounting portion 19 at a predetermined work point. Note that 23 is a positioning point when no correction is performed after a temperature change.

Problems that the invention attempts to solve However, with the above configuration, even if the length of the robot arm changes (expands and contracts) due to temperature changes, there is no compensation for this, and the positioning point at the tip of the robot arm is not corrected. The problem is that the temperature changes with changes in temperature. This will be explained in detail below using FIG. 4.

First, assume that when the tip of the robot's arm is at positioning point 1, the angle of the first arm 4 is θ1a, and the angle of the second arm 5 is θ2a. Therefore, in the control device, the first arm angle is 01as and the second arm angle is 01as with respect to positioning point 1.
The arm angle is stored as 02a. At this time, the arm length of the robot is such that the length of the first arm 2 is L1a1.
It is assumed that the length of the second arm 3 is "2a".

By the way, due to a change in temperature, the length of the first arm is 6.
Suppose that the length of the second arm changes to Llb, and the length of the second arm changes to L2b. Even in this case, the control device outputs the first arm angle as θ1a of 4 and the second arm angle as 02a of 5, as before the temperature change, so the point actually positioned by the robot is 23. The positioning point will be different from the positioning point 1 before the temperature change.

In view of the above problems, the present invention provides a method in which the positioning point of the robot does not change even if the temperature changes.

Means for Solving the Problems In order to solve the above problems, the positioning point correction method of the present invention inputs changes in the arm length of the robot due to temperature into a control device, and in the control device, changes in the arm length are detected. A method is adopted in which the arm angle is corrected according to the

Operation According to the present invention, when a change in the arm length is input to the control device, the arm angle is corrected in accordance with the change in the arm length.

A detailed explanation will be given below using FIGS. 1 and 3.

The length of the first arm 2 is Lla, and the length of the second arm 3 is L.
2a, each arm angle corresponding to positioning point 1 (xa, Ya) is such that the angle of the first arm 4 is θ and the angle of the second arm 4 is θ.
Assume that the angle of arm 5 is 02a.

a At this time, xa = L1aCoSθ1a + L2aCO3θ2a
・・・・・・(1) Ya=L1asinθ1a+L2
It can be expressed as aSlnθ2a' (2).

If a temperature change occurs and the length of the first arm becomes Llb of 6 and the length of the second arm becomes L2b of 7, if you want to make the positioning point at the tip of the arm the same, the length of the first arm 8 becomes The angle θ1b and the angle θ2b of the second arm 9 must satisfy the following equation.

Xa=L1bcO3θ1b+L2bCO5θ2b
'・・・・・・(3) Ya=L1bSi mouth θ1b10L
2bSinθ2b'・・・・・・(
4) If positioning point 1 is stored in the control device in the (x, y) coordinate system, calculate θ1b and θ2b that satisfy (3) and (4) using Xa and Ya as they are.

1 positioning point is each arm angle (θ1.θ2)
If f is stored in the control device, θ1a'θ2&
Calculate xa and Ya by substituting the values of (1) and (2), and then calculate θ that satisfies (3) 9 (4) as before.
1b, θ2b are calculated. If θ1b and θ2b are the first arm angle and second arm angle after the temperature change, respectively, the positioning point of the tip of the robot arm will be the same as the previous position 1, as shown in FIG.

EXAMPLE Hereinafter, a robot according to an example of the present invention will be described with reference to the drawings.

FIG. 2 shows an overview of the robot in the first embodiment of the present invention. In Fig. 2, the difference from the conventional robot (Fig. 6) is that the first arm 1o and the second
The arm is equipped with a sensor (for example, a strain gauge) that detects changes in arm length, and its output is input to the control device.

The operation of the robot configured as described above will be explained below with reference to FIGS. 1, 2, and 3.

When the 12 sensors that detect changes in arm length shown in Figure 2 detect changes in arm length and input the output to the control device 20, the arm angle corresponding to the arm length is calculated according to Figure 3. Correction is made by doing this. By using the corrected angle, the positioning positions of 1 become the same, as shown in FIG.

As described above, according to this embodiment, a sensor for detecting a change in the arm length is provided on the arm, and a means for correcting the arm angle according to the change in the arm length is provided in the control device. Accordingly, even if the robot arm length changes, each taught positioning point can always be the same regardless of temperature changes.

A second embodiment of the present invention will be described below.

In the first embodiment, the change in robot arm length is
However, in the second embodiment, how each arm length changes due to temperature change is stored in advance in the control device. When the temperature is input to the control device in the form of a sensor or program data, the arm length corresponding to the temperature is retrieved from the location stored in the control device and the same correction as in the first embodiment is performed. .

As described above, the control device stores the changes in each arm length due to temperature, extracts the arm length when the temperature is input, and corrects the arm angle according to the change in arm length. By providing this, compensation for the positioning point due to temperature changes can be performed more easily and at lower cost than in the first embodiment.

Effects of the Invention As described above, the present invention inputs changes in the robot arm length due to temperature into the control device, and provides means in the control device for correcting the arm angle in accordance with the change in the arm length. Even if the length of the robot arm changes with the change in temperature, each taught positioning point can always be made the same regardless of temperature changes.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing temperature compensation of an industrial robot according to an embodiment of the present invention, FIG. 2 is a perspective view of the same industrial robot, and FIG. 3 is a flow chart diagram showing a calculation procedure for temperature compensation. FIG. 4 is an explanatory diagram showing changes in arm length due to temperature of a conventional industrial robot, FIG. 6 is a flow chart diagram showing a conventional calculation procedure, and FIG. 6 is a perspective view of the conventional industrial robot. 1... Positioning point, 2... First
Arm length, 3... Length of second arm, 4.
...First arm angle, 5...Second arm angle, 12...Se/su, 19...End effector mounting part, 20... ···Control device.
. Name of agent Patent attorney Toshio Nakao and 1 other person Toi Ritsuka 5 Nime Boishi L 2-11 No. 17-4 Sego 5゛-1 No. 2 '''; ---41 [14 (, tlt + '' 117-Otsu A4
2'7'-" Arithmetic 1 -1 !1---- = Fubua 40 Kakuho 9
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-￥;2 ” +9・-en6147cho7ri hfchojizukaQO-ichiichikori (Oshitatsu 31 2 each 17-i”L Fig. 3 Fig. 6

Claims (1)

[Claims] In an industrial robot having rotating joints, means for inputting changes in robot arm length due to temperature into a control device; means for correcting joint angles of the robot arm in accordance with changes in the arm length; An industrial robot consisting of a control device that operates the robot based on the angle.