Adaptive hybrid position/force control for grinding applications

Application of robotic manipulators for grinding purposes may cause unreasonable behavior during grinding of uneven surfaces such as damaging workpiece surface, or following undesired roughness of the surface depending on the control strategy. This paper presents an adaptive control strategy which is a combination of a closed loop position control to track the desired path, an open loop force control to compensate for contact forces and an adjustable closed loop force control term. The third part of this control strategy, which can be considered the main contribution of this work, makes it possible to choose between position or force control strategy in the normal direction. Several numerical examples are provided to show versatility of this control in confrontation with different type of uneven surfaces.