Dissipative Behaviors of 2R Free-Joint Manipulators with Friction

摘要

Free-joint manipulators (FJM) are second-order nonholonomic systems whose dynamical constraints are nonitegrable. Such systems are known to be underactuated systems which can be controlled byless actuator than the dimension of the configuration space. Previously proposed methods to control FJMs have been based on an assumption of perfectly frictionless free joints. In this paper, we analyze the behaviours of 2R-FJM with friction at free joints in response to periodic inputs via the averaging method. Various models of friction at the free joint are considered and dissipative behaviors caused by friction are revealed. Control methods to position the both joint of 2R-FJM are proposed and the effectiveness of the method is verified by simulations and experiments.