An experimental study on motion error of hexarot parallel manipulator

In this paper, a novel 6-DOF parallel manipulator with coaxial actuated arms is introduced and investigated. This mechanism has six rotating arms, and by rotation of arms about the base, positioning and desired movement of the mechanism is achieved. Sine parallel mechanisms have a nonlinear motion while moving from an initial position to a desired position, investigation of nonlinear error in such mechanisms is of paramount importance. In this paper, inverse and forward kinematics of the mechanism are studied. Nonlinear error of the mechanism's motion in its workspace is extracted using mid-oscillating circle and kinematic relations as well. Moreover, effective parameters on nonlinear motion error of mechanism are determined. The results obtained by theoretical method are further verified through image processing experimental tests. It is found that the results of the theoretical analysis and experimental test are in good consistency.