Abstract:An optimum strategy for driving force distribution, which can hold preload in the robot,was presented. First, an approach for the kinematic and dynamic analysis of redundant planar parallel robot was proposed. In this method, theory of screws was used to deduce the Jacobian matrix, and the Newton-Euler equation was used to calculate wrench of pivot points, and the principle of virtual work was sued to formulate the dynamic equation of motion. Then, the driving forces of 3-RRR and 4-RRR were optimized based on force optimization, respectively and the peak of driving force for 4-RRR is lower than that for 3-RRR. In the end, the internal preload and driving forces of the 4-RRR were optimized based on the power optimization and the variations rules of the driving forces and internal preload were obtained.