Tracking control of two degree of freedom parallel robots with adaptive bounds for the actual torque

Firstly, a further discussion on the modeling of the two degree of freedom parallel robots is carried out, some known formulas on the kinematics are modified and the analytical expressions of the reduced model are given. Secondly, two adaptive PD approaches with adaptive bounds on the actual torque vector or on the physical parameter vector are proposed for the tracking control, where the adaptive laws contain only one adaptive parameter to be tuned online. Finally, the experimental results are included to show the effectiveness of the proposed controllers.