1. Laboratory for Neuromechanics and Biorobotics, Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana 1000, Slovenia;
2. Jožef Stefan International Postgraduate School, Ljubljana, Slovenia;
3. School of Computer Science, University of Birmingham, Edgbaston, The United Kingdom
4. HRI2 Lab, Department of Advanced Robotics, Istituto Italiano di Tecnologia, Genoa, Italy;