1. School of Mechanical, Electrical and Information Engineering, Shandong University, Weihai, China
2. Computer Science Department and the International Max Plank Research School for Intelligent Systems, University of Stuttgart, Stuttgart, Germany
3. School of Control Science and Engineering, Shandong University, Jinan, China
4. Advanced Robotics and Intelligent Systems Laboratory, University of Guelph, Guelph, ON, Canada
5. Department of Computing and Decision Science, Lingnan University, Hong Kong, SAR, China