Material Removal Control for Teleoperated Robotic Sanding

Abstract

During manufacturing of composite parts, minor surface defects are often repaired by applying fairing compound to the affected area and sanding to the desired surface profile. This sanding is commonly performed using hand-held sanding tools leading to ergonomic injuries. Teleoperated robotic sanding completely removes the operator from the dangerous forces and vibrations which were causing these injuries. Unfortunately, with teleoperated robotic sanding the operator's sensory perception is reduced making it difficult to effectively control the depth of material removed. For this reason it is desirable to automatically control the rate of material removal. However, existing methods for controlling the rate of material removal are not compatible with teleoperation as the path of the sander, and the speed along the path are unknown a priori. Therefore, a new method for controlling the rate of material removed was derived. Tests to validate this method have shown it reduces the spatial variation in depth of material removed by at least 30% in simulation vs constant force control. Similar experiments on physical robotic hardware have reduced the variation by at least 20%. Experiments with a human in the loop have shown an improvement of at least 19% in the spatial variation of material removed when compared to constant force control when using the physical robotic hardware. Several qualitative metrics also favor the proposed method. For example, operators often felt they produced a better end result and could remove material more precisely with the proposed method. These results show that controlling the rate of material removal during teleoperated robotic sanding helps produce a better end result.