1. Institute of Robotics and Mechatronics, German Aerospace Center (DLR), Wessling, Germany
2. Institute for Technical Informatics (ZITI), Heidelberg University, Heidelberg, Germany
3. Institute of Robotics and Intelligent Systems, ETH Zürich, Zürich, Switzerland
4. Spinal Cord Injury Center of Heidelberg University Hospital, Heidelberg, Germany
5. Chair of Industrial Design Engineering, Technical University of Dresden, Dresden, Germany