Kinematic accuracy research of a novel six-degree-of-freedom parallel robot with three legs

Based on a novel six-degree-of-freedom (DOF) parallel manipulator mechanism, the forward and inverse kinematics have been worked out. This paper addresses the kinematics accuracy problem of the proposed new parallel robot with three legs (TLPM) due to the location of the U joint errors, clearance and driving errors. According to the generalized kinematic mapping of motions in the workspace, the end-effector's exact output error bound for a standard deviation of the components can have a great influence on the pose (position and orientation) error. The stochastic results are presented; for considering both the location errors clearance and driving in the total simultaneous effect of the errors, the superposition principle is not suitable when any of the errors is considerably larger than the last two errors. The accuracy is intensively studied, a laser tracker is applied to calibrate the errors. The models can be built into the controller and used to compensate for the location of the U joint errors, clearance and driving errors. Experimental results show that the robot accuracy is improved and demonstrated the effectiveness of the proposed method.