Saskia Baltrusch

138 Chapter 5 performed?.” This outcome was assessed in the control and in the exoskeleton condition. Discomfort: In the exoskeleton conditions participants were asked to indicate the discomfort of the prototype after each task by putting a cross on a VAS scale that ranged from “very comfortable” to “very uncomfortable.” The results of the functional testing are presented in section 4.3. 4 Results In this section, first, the results of the component testing are presented, followed by the biomechanical and functional testing of the exoskeleton with users. 4.1 Component Testing The results of the component testing can be found in Figure 9. One single carbon fiber beam produced an output torque of 12 Nm at an angle of 64°. Three beams in parallel, therefore produce a peak torque of 36 Nm. One hip torque source with a pretension of 30% (2.15 cm) produced a peak output torque of 22 Nm, two therefore a peak torque of 44 Nm. The entire exoskeleton consisting of flexible beams produced an output torque of 25 Nm at a trunk angle of 90°. The rigid exoskeleton produced a torque of up to 40 Nm at a trunk angle of 70°. Figure 9: Spinal support (A) . Measured data of one single beam is compared to the data of the model. The model and the measurements coincide. An angular range of 64° was measured which produced a torque of 12 Nm. Torque source hip (B) . Measured data is compared to an analytical model of the MACCEPA 2.0. Up to an angle of 40° the two models coincide for loading. For angles bigger than 40° the measurement data exceeds the modeled torque. For an angular displacement of 95° an output torque of 22 Nm is produced. During unloading, the torque source shows hysteresis. Entire exoskeleton stiffness (C) : The entire exoskeleton stiffness is characterized, once with flexible beams mounted (Flex, Figure 7A) and once with a rigid back interface (Rigid, Figure 7C) mounted.