1. School of Automation, China University of Geosciences, Wuhan 430074, P. R. China
2. Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems, Engineering Research Center of Intelligent Technology for Geo-Exploration, Ministry of Education, P. R. China
3. School of Electrical and Automation Engineering, East China Jiaotong University, Nanchang 330013, P. R. China