1. Robotics and Mechatronics group (RaM), the faculty of Electrical Engineering Mathematics and Computer Science, Technical Medical Centre; University of Twente; Enschede 7500AE the Netherlands
2. Advanced Robotics Department; Istituto Italiano di Tecnologia; Genova 16163 Italy
3. Magnetic Detection and Imaging Department, Faculty of Science and Technology; University of Twente; Enschede 7500AE the Netherlands