A probabilistic framework for learning geometry-based robot manipulation skills

Abstract Programming robots to perform complex manipulation tasks is difficult because many tasks require sophisticated controllers that may rely on data, such as manipulability ellipsoids, stiffness/damping matrices and inertia matrices. Such data are naturally represented as Symmetric Positive Definite (SPD) matrices to capture the specific geometric characteristics of the data, which increases the complexity of hard-coding the data. To alleviate this difficulty, Learning from Demonstration (LfD) paradigm can be used in order to learn robot manipulation skills with specific geometric constraints encapsulated in SPD matrices. Learned skills often need to be adapted when they are applied to new situations. While existing techniques can adapt Cartesian and joint space trajectories to new situations, described by various desired points, the adaptation of motion skills encapsulated in SPD matrices remains an open problem. In this paper, we introduce a new LfD framework that can learn robot manipulation skills encapsulated in SPD matrices from expert demonstrations and adapt them to new situations defined by new start-, via- and end-matrices. The proposed approach leverages Kernelized Movement Primitive (KMP) to generate SPD-based robot manipulation skills that smoothly adapt the demonstrations to conform to new constraints. We validate the proposed framework using a couple of simulations in addition to a real experiment scenario.