Robust Hybrid Position/Force Control for Robot Manipulators

Abstract

This work presents a robust control methodology for hybrid position/force control. It develops a method for the design of controllers of constrained manipulators in the presence of model uncertainties. The control input of this methodology consists of a nonlinear and a linear part. The nonlinear control part gives a new coordinate system which can be defined for any constraints. By this coordinate system robot dynamics is decoupled and input spaces are devided into two orthogonal spaces of position and force control. Position control gives desired velocity of the end-effector through the constraints and force control gives desired reaction force on the constraints. The linear control part improves robustness properties of the proposed nonlinear hybrid control scheme. According to the nonlinear part the linear part is devided into two parts of position and force control. Model feedback control scheme is applied to the linear part of position control and integral control is used in the linear part of force control in order to suppress tracking errors due to model uncertainties. The robustness of the proposed hybrid control scheme is demonstrated through simulation of a constrained 2 degrees of freedom manipulator.