Dynamics and Optimized Torque Distribution Based Force/position Hybrid Control of a 4-DOF Redundantly Actuated Parallel Robot with Two Point-contact Constraints

摘要

A 4-DOF redundantly actuated parallel robot (RAPR) for jaw movement achieved by adding two point-contact constraints (higher-kinematic-pairs, HKPs) is presented. The inverse dynamics and driving force optimization model based on pseudo-inverse method are established. In order to overcome the disequilibrium of driving forces of the redundant chains caused by inclusion of point-contact constraints, an optimized torque distribution based force/position hybrid control (OTDFP control) method for trajectory tracking is proposed for this RAPR. Experiments are carried out to evaluate the OTDFP control. Comparison with the conventional position control is performed, showing that the OTDFP control can reduce torque fluctuation and tracking errors of the RAPR. The chewing experiment of silicone shows the RAPR is not only able to track mandibular movement, but also able to emulate chewing force and temporomandibular joint (TMJ) force under the OTDFP control.