1. Department of Rehabilitation Medicine, Erasmus Medical Center, 3015 GD Rotterdam, The Netherlands
2. Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands
3. Rijndam Revalidatie, Westersingel 300, 3015 LJ Rotterdam, The Netherlands
4. Faculty of Mechanical Engineering, Rhine-Westphalia Technical University of Aachen, 52062 Aachen, Germany