1. Key Laboratory of Electronic Equipment Structure Design, Ministry of EducationXidian UniversityXi'an710071People's Republic of China
2. Berkeley Sensor and Actuator CenterDepartment of Mechanical EngineeringUniversity of California at BerkeleyBerkeleyCA 94720USA
3. No. 29 Research Institute of China Electronics Technology Group CorporationChengdu610036People's Republic of China
4. No. 39 Research Institute of China Electronics Technology Group CorporationXi'an710065People's Republic of China