Lower-mobility robot kinematics calibration method based on monocular vision

Abstract

The invention relates to a lower-mobility robot kinematics calibration method based on monocular vision. The calibration method comprises the steps that according to existing calibration variable U, an absolute value coding chessboard is utilized for carrying out grading distance measuring and optimizing on multiple sets of displacement delta` of a monocular vision sensor installed on a lower-mobility robot; a conversion angle alpha between a checker coordinate system and a base coordinate system is calibrated, coordinate conversion is carried out on the displacement delta` according to the conversion angle alpha, the displacement delta is obtained, and multiple sets of observation variables Vk are obtained in combination with a conversion value of the motor angle theta; the constraint relation is utilized and combined with the multiple sets of observation variables Vk to optimize the calibration variable U to judge whether the variable U reaches location precision or not, if yes, kinematics calibration of the lower-mobility robot is completed, and if not, measurement is carried out again. Compared with the prior art, the method has the beneficial effects of being high in distance measuring precision of the monocular vision sensor and high in practicality and saving cost.

Description

technical field [0001] The invention relates to the field of calibration of industrial robots, in particular to a kinematics calibration method of a robot with few degrees of freedom based on monocular vision. Background technique [0002] Accurately measuring the displacement of the working end of the robot is the core of completing the robot calibration. Its pose is usually measured with the help of external sensors. Commonly used equipment includes precision measuring instruments such as three-coordinate measuring instruments and theodolites. However, the common disadvantages of these solutions are that the equipment is expensive (hundreds of thousands or even millions), and the use method is cumbersome and complicated. It often requires on-site calibration and manipulation by professionals, and the threshold for use is high; on the other hand, such equipment usually requires a large It is difficult to meet the requirements of the production site for high efficiency and...

AI Technical Summary

Problems solved by technology

[0005] 1. Robots often need a larger working space. In order to keep the target always within the field of view, this requires the camera to have a large field of view, and the corresponding size of each pixel is very large (difficult to control within 1mm 2 Within), it is difficult to accurately locate

[0006] 2. More targets will appear in the edge area of ​​the picture in the field of view

And this part has very serious radial distortion

Even after the camera is calibrated, the error it brings will cause large fluctuations in the measurement results, which will interfere with the accuracy of the results

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