School of Automation, Northwestern Polytechnical University, Xi'an 710072, China;
School of Electrical Engineering and Computer Sciences, Technical University of Berlin, Berlin 10587, Germany;
School of Automation, Northwestern Polytechnical University, Xi'an 710072, China;
School of Mechanical Engineering and Transport Systems, Technical University of Berlin, Berlin 10587, Germany;
School of Electrical Engineering and Computer Sciences, Technical University of Berlin, Berlin 10587, Germany;