1. Institute of Electrical Control Engineering; National Chiao Tung University; Hsinchu 30010 Taiwan
2. Department of Electrical and Computer Engineering; University of Texas at San Antonio; San Antonio 78249 TX USA
3. College of Engineering; Nanjing Agricultural University/Jiangsu Key Laboratory for Intelligent Agricultural Equipment; Nanjing 210031 China
4. Institute of Automation; Qufu Normal University; Qufu 273165 China