1. Suzhou Automotive Research Institute, Tsinghua Univ., Suzhou, Jiangsu, China.
2. School of Automation Science and Electrical Engineering, Beihang Univ., Beijing, China.
3. School of Rail Transportation, Soochow Univ., Suzhou, Jiangsu, China.
4. School of Computer Science and Technology, Soochow Univ., Suzhou, Jiangsu, China.