Exit Point, Initial Length and Pose Self-calibration Method for Cable-Driven Parallel Robots

Abstract

A calibration process simulation for the interest variable values, including Cartesian coordinates of exit points, moving platform poses and initial cable lengths is performed. The simulation considers the modelling of the pulleys at exit points, and is carried out using nonlinear least square method. The effects of calibration tuning parameters and of measurement pose number on calibration quality are analyzed. As a result, the calibration quality increases with the decrease of tuning parameters and the increase of measurement pose number. The use of Jacobian matrix of the interest function fi,j also leads to a better calibration quality.

An approach for predicting the calibration accuracy in planar cable-driven parallel robots and experiment validation

“…As the CDPR has m = 2 cables, the least number of measurement poses is n = 6. A similar simulation process is used in [9,10]. Arbitrary errors are added on x to simulate the approximately known system variables.…”

“…Detailed pulley modelling is considered in the geometric model, which results in the shift of cable exit point from A i to A i [9,2], shown in Fig. 4.…”

An Approach for Predicting the Calibration Accuracy in Planar Cable-Driven Parallel Robots

“…As the CDPR has 𝑚 = 2 cables, the least number of measurement poses is 𝑛 = 6. A similar simulation process is used in [9,10]. Arbitrary errors are added on x to simulate the approximately known system variables.…”

“…𝑚 = 2 and 𝑛 is the total number of measurement poses. Detailed pulley kinematic modelling is described in [2,9] and is illustrated in Fig. 3.…”