Saskia Baltrusch

134 Chapter 5 Figure 6: Component testing: Spinal support (A) . The beams are tested on the one hand to identify the material properties, such as the Young’s modulus E and on the other hand to identify the torque angle characteristic. The carbon fiber beams are fixed on the base. A force, which is recorded with a load cell, is applied at the top. Five points on the beams are tracked using a motion capture system (Vicon Vero). Torque source hip (B) . In order to validate the design of the torque source and to identify the torque angle characteristic, the hip actuator is subjected to a external force. The force is recorded with a load cell, while at the same time the two markers on the rotating, top part of the actuator are tracked; Loading support verification (C) . Subject 1 is wearing the bottom part of the exoskeleton. The exoskeleton is equipped with markers, whose position is recorded with the motion capture system. Subject 2, with known mass m is standing on a force plate, while exciting the spinal part of the exoskeleton with the forces F 1 and F 2. The known length of the spinal part of the exoskeleton allows to calculate the support torque at lumbar level τ exo . In order to verify the loading support of the single components combined, the torque-angle behavior of the entire exoskeleton was identified. The exoskeleton was equipped with Optotrak markers, while one user wore the hip part of the exoskeleton (Figure 6C). Instead of connecting the shoulder interface to the user, a second person standing on a force plate would excite the exoskeleton while the wearer flexes out of the way. The experiment was once performed with the flexible beams (Figure 7A) and once with the rigid aluminum tube (Figure 7C). The recorded data was processed with a custom MATLAB script. The resulting support torque-angle characteristic is reported in section 4.1.