Accuracy analysis of a modified Stewart platform manipulator

Relation between the joint displacement errors of Stewart platform manipulators and the end effector accuracy is presented. The position errors of the joints and the actuation errors and backlash are included to the kinematic model. A closed-form forward kinematics solution of the end effector error is derived from the inverse kinematics solution. The method is applied to a modified Stewart platform manipulator, and end effector error ellipsoids are computed. The analysis shows that the method can be used in evaluating the accuracy of prismatic parallel manipulators