Integration of planning and execution in force controlled compliant motion

This paper presents the compliant task generator: a new approach for the automatic conversion of a geometric path generated by a compliant path planner to a force based task specification for a compliant robot controller. Based on the geometric model of a moving object and its environment, a compliant path planner generates a set of six-dimensional positions x_1...m and their corresponding contact formations CF_1...n. The compliant force controller, which executes a planned path under force feedback using the hybrid control paradigm, expects a desired force w_d, velocity t_d and position x_d at each time-step, together with their force and velocity controlled subspaces W and T. To specify these controller primitives, we add information about the desired dynamic interaction between the moving object and its environment, in the form of the desired kinetic energy E_kin of the moving object and the potential energy E_pot in the contacts with the environment, together with the inertia and stiffness matrix M and S. We fully automated the conversion process of the compliant planner output together with the added information about the dynamic interaction, to a force based task specification. This eliminates the requirement of human intervention between the planning and execution phase. The presented approach applies to all compliant motions between polyhedral objects, and is verified in a real world experiment.