Correction of Force Errors for Flexible Manipulators in Quasi-Static Conditions

This paper deals with the problem of controlling the interactions of flexible manipulators with their environment. For executing a force control task, a manipulator with intrinsic (mechanical) compliance has some advantages over the rigid manipulators commonly employed in position control tasks. In particular, stability margins of the force control loop are increased, and robustness to uncertainties in the model of the environment is improved for compliant arms. On the other hand, the deformations of the arm under the applied load give rise to errors, that ultimately reflect in force control errors. This paper addresses the problem of evaluating these errors, and of compensating for them with suitable joint angle corrections. A solution to this problem is proposed in the simplifying assumptions that an accurate model of the arm flexibility is known, and that quasi-static corrections are of interest.