Physical Interaction Interpretation in Industrial Robotics Using Dynamic Time Warping Principles

This paper presents an approach to interpretation of the context of physical interaction of a robot with its surroundings using principles of Dynamic Time Warping (DTW). Forces originating from physical interaction reflect their influence on robot joints through the measurements of robot joint currents, which deviate from their values without interaction. Contextual information is annotated to a representative example of deviations and used as reference value for the contact task-induced signal deviations. Context of ongoing task executions obtained by comparing recent measurements of deviations and comparing them with the most similar section of their reference values using modifications of the original DTW algorithm. The analysis is based on previously recorded experimental measurements of robot joint currents while performing different types of contact tasks including assembly and load manipulation tasks. Results are discussed in terms of their reliability, accuracy and additional signals or rules needed to interpret them correctly.