1. College of Control Science and Engineering, Zhejiang University, Hangzhou, China
2. Neuroinformatics Group, Center for Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany
3. Bristol Robotics Laboratory, University of the West of England, Bristol, U.K.
4. Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, P.R. China