Online motion monitoring for a class of 3-legged 6-DOF parallel robots

Based on the local product-of-exponentials (POE) formula, this paper proposes an effective approach to solve the inverse displacement analysis for a class of modular 3-legged parallel robots by Paden-Kahan sub-problems. Since passive joint displacements can be solved together with solving active joint, so that the solved passive joint displacements can be regarded as guess solution to calculate forward kinematics by traditional numerical solution method. Through comparing with traditional iterative numerical solution method, proposed approach can evidently improve computation efficiency for forward kinematics. The effectiveness of the proposed approach has been demonstrated by machining demonstrations with online motion monitoring for a workpiece with spherical surface.