1. College of Information Science and Technology, Nanjing Forestry University, Nanjing, China
2. College of Information Science and Engineering, Qilu Normal University, Jinan, China
3. School of Logistics and Transportation, Central South University of Forestry and Technology, Changsha, China
4. Department of Electrical and Computer Engineering and the Institute of Systems and Robotics, University of Coimbra, Coimbra, Portugal