1. Hongpeng Cao is with School of Engineering and Design, Technical University of Munich,Munich,Germany,85748
2. Wayne State University,Yanbing Mao is with Engineering Technology Division,Detroit,MI,USA,48201
3. University of Illinois at Urbana-Champaign,Department of Computer Science,Urbana,IL,USA,61801
4. School of Engineering and Design and Institute of Robotics and Machine Intelligence, Technical University of Munich,Munich,Germany