C-surface applied to the design of an hybrid force-position robot controller

C-surfaces are defined in the parameter´s space by the border between the subspace where the robot´s positions are constrained by the surrounding and the subspace where there is no contact. Thus force control must be performed along the C-surface normal and position control along the tangent hyperplane of the C-surface. We have shown that the C-surface normal can be calculated by the use of force measurements. This yield to the design of an hybrid force-position controller where the direction to be force controlled is automatically determined. Experimental results are presented and compared to simulation for the surface following problem. Assembly tasks and the turning of a crank have been executed in simulation by using this hybrid controller. Experiments with a parallel manipulator are currently under development.