A COMPARATIVE-STUDY OF INVERSE DYNAMICS OF MANIPULATORS WITH CLOSED-CHAIN GEOMETRY

The dynamics of closed‐chain manipulators was not studied as extensively as that of open‐chain manipulators. In this article, the inverse dynamics of two types of closedchain manipulators, namely, a pantograph manipulator and a five‐bar manipulator, are studied. The recently developed computationally efficient method1 is applied to both manipulators. The computational efficiency of inverse dynamics is evaluated in terms of both formulating methods (the method in reference 1 vs. the Lagrange method), and geometric structures (the pantograph vs. the five‐bar). The inverse kinematics computation of pantogaph manipulators is expected to be simpler than that of five‐bar manipulators simply because of the decoupling nature of the pantogaph mechanisms. On the contrary, the inverse kinetics of the pantograph is less efficient than the five‐bar because more links are involved during motion. It is also found that the overall inverse dynamics which includes both the inverse kinematics and kinetics of the pantograph manipulators, is more computationally efficient than that of the five‐bar, mainly due to the simple kinematics of the pantograph. Copyright © 1990 Wiley Periodicals, Inc., A Wiley Company