Estimation of Anchor Points for Fully-Constrained and Redundant Planar Cable Robots

Abstract

Cable-based robots generally perform better than other parallel robots with rigid links in terms of wider workspace and higher acceleration of end effector because of lightweight of robot links. Cable based robots allow an easy mounting and remounting for outside applications; however, this requires a precise assembly of components at the cable anchor points. In this study, firstly a parametric model is developed for estimation of position errors of anchor points for fully-constrained and redundant planar cable robots. A novel method based on inclusion of virtual cables facilitates the linear separation of the uncertain parameters from the input-output signals for redundant planar robots. In addition, the adaptive law (parameter estimator) updates the estimated parameters using the least squares algorithm. The simulation results show that the least squares method reduces the time of estimation convergence compared to gradient algorithms. Furthermore, the least squares method allows simple persistent excitation signals to estimate parameters.