ELASTIC-LINK MANIPULATORS - MODELING, SIMULATION AND EXPERIMENTS

A position and force control concept for an industrial robot with elas ticity in joints and links is developed and experimentally tested. The manipulator is modelled as a multibody system with distributed parame ters. The developed control strategy allows the robot to perform endle ss constrained trajectories, without visible gripper vibrations. This control concept is an extension of the nonlinear decoupling control co mplemented with a time-variant feedback controller, which is designed for several points along the reference path. This approach is performe d in three steps. First, a suitable Cartesian reference path for the f lexible robot is generated taking into account its high demand on move ment smoothness. Second, the correspondent joint trajectories for the rigid robot are generated. This rigid robot's path is then corrected b y regarding the elastic influences of all links and joints. Third, a t ime-variant controller is added that feeds back joint positions/veloci ties and strain gauge measurements at the elastic arms in order to red uce trajectory deviations and damp remaining oscillations. This contro l strategy is simulated and experimentally tested on a five-DOF labora tory robot with two flexible arms in order to polish a plane surface. Arm flexibility is tridimensional.