Abstract
Coordinate transformation plays an indispensable role in industrial measurements, including photogrammetry, geodesy, laser 3-D measurement and robotics. The widely applied methods of coordinate transformation are generally based on solving the equations of point clouds. Despite the high accuracy, this might result in no solution due to the use of ill conditioned matrices. In this paper, a novel coordinate transformation method is proposed, not based on the equation solution but based on the geometric transformation. We construct characteristic lines to represent the coordinate systems. According to the space geometry relation, the characteristic line scan is made to coincide by a series of rotations and translations. The transformation matrix can be obtained using matrix transformation theory. Experiments are designed to compare the proposed method with other methods. The results show that the proposed method has the same high accuracy, but the operation is more convenient and flexible. A multi-sensor combined measurement system is also presented to improve the position accuracy of a robot with the calibration of the robot kinematic parameters. Experimental verification shows that the position accuracy of robot manipulator is improved by 45.8% with the proposed method and robot calibration.
Highlights
Multi-sensor measurement systems usually have different coordinate systems
This paper paperproposes proposes a simple method of coordinate transformation in a multi-sensor
The accuracy of the transformation method is 10−3 mm. It reduces the cumulative error of the coordinate transformation in the robot calibration, thereby improving the accuracy of the robot calibration
Summary
Multi-sensor measurement systems usually have different coordinate systems. The original data must be transformed to a common coordinate system for the convenience of the subsequent data acquisition, comparison and fusion [1,2]. To achieve the aim of calibration, the primary process is to unify the coordinate systems of a calibrated instruments and the robot In this way is it possible to use the measurement results to correct the kinematic parameters of the robot. Zhang et al proposed a practical method of coordinate transformation in robot calibration [19] This method rotates three single axes of the robot to calculate the normal vectors in three directions, combined with the data of the calibration sensor. The method avoids the need to solve an equation and complex calculations, but it might be affected by any manufacturing errors of the robot and requires a calibration sensor with a large measuring range that can cover the full working range of the robot
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