A new method for position control of planar 3-Dof underactuated robots

Position control of nonholonomic 3R underactuated robots is investigated in this paper. A new method is proposed for motion control of this kind of system. The control objective is to move the links from rest to target configuration with zero velocity. The whole control process can be divided into two stages, the first stage is to achieve the position control of first link based on the dynamic model, the desired position of the second active and third passive links are reached in the second stage without considering the motion of first link. Fuzzy control method is introduced in the second stage and the motion of the system can be considered to be the resultant motion of the folding or unfolding of passive joints and the revolution of active joints. The genetic algorithm is utilized in the best fuzzy rules generating. At last numerical simulations illuminate the effectiveness of the proposed method.