Context-driven movement primitive adaptation

Daniel Wilbers, Rudolf Lioutikov, Jan Peters

Abstract: Humanlike robot skills, e.g., cleaning a table or handing over a plate, can often be generalized to different task variations. Usually, these are start-/goal position, and trained environment changes. We investigate how to modify motion primitives to context changes, which are not included in the training data. Specifically, we focus on maintaining humanlike motion characteristics and generalizability, while adapting to unseen context. Therefore, we present an optimization technique, which maximizes the expected return and minimizes the Kullback-Leibler Divergence to the demonstrations at the same time. Simultaneously, our algorithm learns how to linearly combine the adapted primitive with the demonstrations, such that only relevant parts of the primitive are adapted. We evaluate our approach in obstacle avoidance and broken joint scenarios in simulation, as well as on a real robot.