ARTICLE Zeestraten_RAL_2017/IDIAP An Approach for Imitation Learning on Riemannian Manifolds Zeestraten, M. Havoutis, I. Silverio, J. Calinon, Sylvain Caldwell, D. G. learning from demonstration Riemannian manifolds robot learning IEEE Robotics and Automation Letters (RA-L) 2 3 1240-1247 2017 https://doi.org/10.1109/LRA.2017.2657001 URL 10.1109/LRA.2017.2657001 doi In imitation learning, multivariate Gaussians are widely used to encode robot behaviors. Such approaches do not provide the ability to properly represent end-effector orientation, as the distance metric in the space of orientations is not Euclidean. In this work we present an extension of common probabilistic learning from demonstration techniques to Riemannian manifolds. This generalization enables the encoding of joint distributions that include the robot pose. We show that Gaussian conditioning, Gaussian product and nonlinear regression can be achieved with this representation. The proposed approach is illustrated with examples on a 2-dimensional sphere, as well as with an example of regression between two robot end-effector poses, and by extending TP-GMM and GMR to Riemannian manifolds.