Actual Kinematics Performance Analysis for Lower Degrees of Freedom Parallel Manipulators

For lower degree of freedom parallel robot, the relations between revolute pair and prismatic pair are analyzed by using screw theory. According to the relations, the constraint errors due to manufacturing and installation are proposed. Three basic types of constraint errors are identified, and an approach to evaluating the effects of constraint errors on characteristics of parallel manipulators is proposed. The modeling for the lower degree of freedom parallel robot with identical limbs of constraint errors is established. The actual motion is analyzed in order to validate the theory.