1. Engineer, College of Computer and Control Engineering, Nankai Univ., Tianjin 300350, China; Tianjin Key Laboratory of Intelligent Robotics, Nankai Univ., Tianjin 300350, China; AVIC Radar and Avionics Institute, Wuxi 214063, China.
2. Professor, College of Computer and Control Engineering, Nankai Univ., Tianjin 300350, China; Tianjin Key Laboratory of Intelligent Robotics, Nankai Univ., Tianjin 300350, China.
3. Associate Professor, College of Computer and Control Engineering, Nankai Univ., Tianjin 300350, China; Tianjin Key Laboratory of Intelligent Robotics, Nankai Univ., Tianjin 300350, China (corresponding author).
4. Professor, Dept. of Electrical and Mining Engineering, Univ. of South Africa, Florida 1710, South Africa.