1. Research Group on Rehabilitation and Inclusion, ARC Seibersdorf research GmbH, Viktor Kaplan Str. 2, A-2700 Wr. Neustadt, Austria. Tel.: ; Fax: ; E-Mail: barbara.prazak@arcsmed.at
2. Mechatronic Automation Systems, Group for Intelligent Robotics, ARC Seibersdorf research GmbH, A-2444 Seibersdorf, Austria