Saskia Baltrusch

135 Chapter 5 Figure 7: Different exoskeleton configurations were tested: (A) Flexible exoskeleton with slider unlocked. (B) Flexible exoskeleton with slider locked. (C) Rigid exoskeleton with slider unlocked. (D) No exoskeleton. Written informed consent was obtained from the participant to publish this picture. 3.2 User Experiments All experiments involving human subjects were approved by the medical ethical committee of the VU medical center (VUmc, Amsterdam, The Netherlands, NL57404.029.16). Biomechanical Testing Three young, healthy male subjects (average age: 30 years, average height: 171.5 cm, average weight: 66 kg) participated in the biomechanical testing of the prototype. During the experiment, participants were asked to perform a range of motion (ROM) in all three directions; flexion-extension (y), lateral bending (x), and rotation (z), while holding the knees as straight as possible without locking the knee. Subjects were asked to put the same amount of effort in each trial when wearing the different exoskeleton configurations (Figure 7). In total, subjects performed four maximal ROM tasks, differing in the configuration of the exoskeleton: 1. Exo flex-slider : Flexible back structure, with back slider unlocked 2. Exo flex-no slider : Flexible back structure, with back slider locked 3. Exo rigid : Rigid back structure, slider unlocked 4. No Exo : Not wearing any exoskeleton 5