Position Control of a 3-DOF Horizontal Underactuated Robot

Position control of a 3-DOF horizontal underactuated robot is investigated.A new fuzzy control system based on hierarchical control idea is proposed for this kind of robot.The endpoint position control of this underactuated system can be regarded as the folding or unfolding motion of the passive joint and the rotation of active joint.The first joint follows the predefined trajectory,and then the second joint and the third joint achieve the position control based on the dynamic coupling of each other.The control torque or voltage of the second active joint are determined by the weighted sum of the output parameters of fuzzy control.Using this control method,the numerical simulation and experiment of 3R underactuated robot for the tip point-to-point(FTP) position control are implemented in operational space.