Industrial robot TCP (Tool Central Point) calibration method based on uniform attitude distribution

Abstract

The invention discloses an industrial robot TCP (Tool Central Point) calibration method based on uniform attitude distribution, and belongs to the technical field of industrial robot end tool calibration. The method comprises the following steps of: establishing an initial measuring point configuration by taking 'six-point calibration method' of an industrial robot as a primary calibration basis;constructing virtual points which are uniformly distributed on a spherical surface taking a fixed reference point as a spherical center by adopting a mechanical repulsion iterative method, and adjusting the virtual robots group by group to ensure that the centers of the tail ends of sixth axes of the virtual robots are positioned at the virtual points; and finally, adjusting the actual robot to the configurations of the screened measuring points, and solving the final TCP calibration result by using a least square spherical surface fitting method. The method solves the randomness of robot attitude selection and the nonuniformity of distribution when the current fixed reference point method is used for calibration, so that the robot attitude is uniformly distributed around the fixed reference point at each measuring point, the difference degree of the robot attitude between the measuring points is increased to the maximum extent, and the calibration precision can be effectively improved.

Description

technical field [0001] The invention belongs to the technical field of industrial robot terminal tool calibration, and in particular relates to a TCP calibration method for industrial robots based on uniform posture distribution. Background technique [0002] With the rapid development of my country's automated manufacturing industry, labor costs continue to rise, and industrial robots are more and more widely used in the field of industrial automated manufacturing. In practical applications, the robot completes various tasks through tools installed on the end flange, and the offset of the Tool Central Point (TCP) relative to the end position is mostly unknown or inaccurate Yes, robot tool TCP calibration is the process of calculating the position identification of the tool end relative to the robot end coordinate system. Usually, the offset is accurately calculated by a certain method without the use of external measurement tools. The accuracy of tool calibration directly ...

AI Technical Summary

Problems solved by technology

During the implementation of the fixed reference point method, the key factor affecting the calibration accuracy is the difference between the robot attitude when multiple TCP points coincide with the fixed reference point. However, the current "four-point method" or "six-point method" is practical During operation, the selection distribution of the robot posture by the staff is random, especially when the four points are distributed on the side of the reference point, the concentration of the distribution positions limits the range of the robot’s posture, resulting in a reduction in the distance between the measurement points. The degree of difference between attitudes, thus leading to an increase in the calibration error

[0006] In order to solve the calibration error problem of the "four-point method", the Chinese invention patent application "a TCP calibration method for industrial robots" (application publication number CN106502208A) discloses a multi-point TCP calibration method. Determine the equations, and then use the least squares method to achieve tool calibration. The algorithm is simple to implement, and the calibration error is reduced to a certain extent. However, this method still does not solve the problem that the difference between the attitudes cannot be optimized due to the randomness of the robot attitude selection distribution. , since the coefficient matrix of the overdetermined equation system is composed of the difference between the attitude matrix of the robot end at different measurement points, when the attitude distribution of the robot is uneven, the condition number of the matrix will be increased to form an ill condition, which will cause errors in the calibration results

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