Rozo, L., S. Calinon, D. Caldwell, P. Jimenez, and C. Torras. “Learning Collaborative Impedance-Based Robot Behaviors”. Proceedings of the AAAI Conference on Artificial Intelligence, vol. 27, no. 1, June 2013, pp. 1422-8, doi:10.1609/aaai.v27i1.8543.