JPS59129682A - Method of positioning electric type 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 Advantages of the Invention j1] The present invention relates to a positioning method for an electric robot, and in particular,
The present invention relates to a positioning method for improving the positioning accuracy of an electric robot having an arm rotatable in a vertical plane.

[Prior art]

In a conventional method for positioning an electric robot, a target value for positioning is determined by using a calculation formula that assumes that all the arms of the electric robot are rigid bodies.

This will be explained using the first word (Kyou).

FIG. 1 is a schematic side view of an electric robot having two degrees of freedom in a vertical plane. This electric robot base 5,
The robot is composed of an upper arm 1, a motor 3 for rotating the upper arm 1, a forearm 2 for the arm, a motor 4 for rotating the forearm 2, and a hunt 6 for the tip of the robot. Note that arrow A is the direction of gravity.

In the electric robot configured in this way, the base 5
The length of the upper arm 1 is tI, the length of the front IN 2 is also tl, and the base of the base 5 is the origin O of the coordinates.
Taking X@ in the horizontal direction and Z axis in the vertical direction,
...If the target position of motor 6 is given as (xd, zd), the rotation target angle θl'l+ θ2 of motor 39.4
Conventionally, d was calculated using the following equations (L) and (2).

(1) These formulas (1) and (2+) assume that upper arm 1 and forearm 2 are rigid bodies, and calculate the rotation target angle θId + θ2d from the target position (xd, Zd). was calculated, ignoring the deflection due to gravity and the deflection due to the load applied to the hand 6 in Situation 2 (the stiffness of the base 5 is Since it is extremely large, there is no problem in considering the base 5 as a rigid body).

For this reason, the conventional method for positioning an electric robot has the disadvantage that an error occurs in positioning the tip of the robot due to the bending of the arm.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks of the prior art, and provides an electric robot having an arm rotatable in a vertical plane and positioning the tip of the robot using a motor. The purpose of this invention is to correct errors and provide a positioning method with excellent positioning accuracy.

[Summary of the invention]

The configuration of the electric robot positioning method according to the present invention is as follows:
In a positioning method for an electric robot that has a rotatable arm in the vertical section and uses a motor to position the tip of the robot, the rotation target angle is calculated from the target position using a calculation formula that assumes the arm is a rigid body. After rotating the motor by the amount of current flowing through the motor, calculate the inclination angle of the arm deflection curve due to the torque due to the load and the torque due to its own weight, which is determined from the current value flowing through the motor, and set this inclination angle to the rotation target angle. The positioning is repositioned to the added corrected rotation target angle.

[Embodiments of the invention]

The present invention will be explained below with reference to Examples.

The bending of the arm of the electric robot is due to the torque l11B due to the arm's own weight and the torque rilt due to the load applied to the tip of the robot.

Regarding the former torque T due to gravity, the mass and shape 9 dimensions of each arm are already %0 at the time of design, and the target rotation angle of the motor is also the same at the time of positioning, so r3iJ
The torque "I"5 can be easily calculated from the recorded specifications and the rotation target angle at the time of positioning.

On the other hand, the torque due to the load on the robot tip - Ill
Although t is unknown, the output torque T of the motor at the time of positioning, 1. It is noted that the following equation (3) holds between the torque llt due to the load and the torque llt due to the load.

'I m -'l s + T t +'1' f・
(3) However, T□: Output torque lpS during positioning; Torque due to gravity Tt: Torque due to load Tf: Static friction torque Here, torque T6 due to gravity can be easily calculated as described above. 1 Static friction torque T+ is the inherent torque applied to the motor due to friction, and is also known. Furthermore, the output torque T□ is proportional to the current flowing through the motor,
The relationship is current value i x proportionality constant, and since this proportionality constant is determined by the motor, the output torques T and n can be determined by detecting the current value l. Therefore, the torque Tz due to the load can be calculated from the following equation (4), which is a modification of the above equation (3).

Tt=T,,, T, Tf...
...(4) As described above, the torque T5 due to gravity is
If the torque Tt due to the load is known, the torque Tg.

The angle of inclination of the arm deflection curve due to Tt can be easily calculated from the elementary theory of beams in mechanics of materials.

Based on the basic matters explained above, a method for positioning the electric robot according to FIG. 1 described above will be explained using FIG. 2.

FIG. 2 shows an electric robot according to an embodiment of the present invention!・It is a flowchart of the positioning method.

First, the specifications of the upper arm 1 and forearm 2, the proportionality constants of the motors 3 and 4, and the static friction torque TB.

Tl2 (rlN, %f2 is the static friction torque Tf when focusing on the motors 3 and 4, respectively. The subscript 1.2 is used in the same manner hereinafter), and the target position of the hand 6. Teach (X,,zd) and start the electric robot.

A microcomputer in the control device (not shown) calculates the rotation target angles θId and θ2d of the motors 3 and 4 from the eye position (Xd, Zd) according to equations (1) and (2), respectively. The torque Tel, 'I'82 due to gravity of the upper arm 1 and forearm 2 is calculated using the respective specifications one rotation target angle θId + θ2d.Motor 3,
4 are rotated by θld+θ2d, and the hand 6 is positioned.

The current values 'l+'2 of the motors 3 and 4 at this time are detected, and the respective output torques Tm1. TII+2
is calculated using the proportionality constant. Upper arm 1. forearm 2
The torques Tt+ and Tzz due to the load are calculated by the above equation (4).

The inclination angle θ1 of the deflection curve of the upper arm 1 due to the torque Tsl due to gravity and the torque Tt1 due to the load is calculated using the beam calculation formula of mechanics of materials already stored in the microcomputer. Similarly, the inclination angle θ2 of the deflection curve of the forearm 2 due to the torque TS2 due to gravity and the torque T t 2 due to the load is calculated. The oblique angle θ around these
l and θ2 are the rotation target angle θld+θ, respectively.
2d, and the corrected rotation target angle θId+θ2
d is calculated from the following equations (5) and (6).

θld”2 θld+θ1・・・・・・・・・(5) θ2
．． =θ2d+θ2 ・・・・・・・・・
...(6) The rotation angles of motors 3 and 4 are each θId
The above control process, in which the positioning is repositioned to +θ2d and the positioning of node 6 is completed, is automatically performed when the electric robot is started.

According to the embodiment described above, the upper arm 1 and the forearm 2,
Since the influence of deflection caused by the torque due to the robot's own weight and the torque due to the load applied to the tip of the robot is corrected, there is an effect that errors in positioning the node 6 can be eliminated.

[Effects of the Invention] As explained in detail above, according to the present invention, the deflection of the arm of an electric robot having an arm rotatable in a vertical plane and in which the tip of the robot is positioned by a motor is improved. It is possible to provide a positioning method with excellent positioning accuracy by correcting positioning errors due to the above.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of an electric robot having two free angles in a vertical plane, and FIG. 2 is a flowchart of a method for positioning an electric robot according to an embodiment of the present invention. 1... Upper arm, 2... Forearm, J... Motor, 4... Motor, 6... Hand, θld+θ2d... Rotation target angle, θld+θ2d... Corrected rotation target angle. Agent Patent attorney Kosaku Fukuda (and 1 other person) Figure 1

Claims (1)

[Claims] 1. In a positioning method for an electric robot that has an arm that can rotate within a vertical direction and uses a motor to position the robot destination ψ1111, the target position is calculated using a calculation formula that assumes the arm is a rigid body. After rotating the motor by the desired rotation angle, calculate the torque due to the load obtained from the current value flowing through the motor, and the slope angle of the deflection curve of the arm due to A method for determining the position of an electric robot, comprising repositioning to a corrected rotation target angle obtained by adding an oblique angle to the rotation target angle.