Saskia Baltrusch

236 Chapter 9 increased by 17% when wearing the Laevo exoskeleton, indicating hindrance during walking. These results were in line with the findings of Chapter 3. These findings stressed the need for a support system that can be disengaged depending on activities performed. Design improvements to be considered in the SPEXOR development were, therefore, provisions to allow full and unhindered range of motion of hips and trunk to increase versatility and user acceptance. Furthermore, the results showed that the support level provided by the Laevo exoskeleton was too low to elicit large effects on muscle activity and functional performance. Thus, another design criterion for the SPEXOR exoskeleton was an increase of support level without affecting versatility. Consequently, the SPEXOR design comprises of flexible beams, which run in parallel to the spine, providing a large range of motion and increased and variable torque capacity. It further features a self-aligning hip joint module with a clutch to disengage the support between activities, as described in Chapter 5. In this chapter, single component testing and pilot testing with a small sample size revealed that the SPEXOR exoskeleton has the potential to provide full range of motion, unobstructed hip flexion and unloading of the lower back. I tested these promising results from Chapter 5, by repeating the benchmarking tests from Chapters 3 and 4 with the new SPEXOR exoskeleton. In Chapters 6 and 7, two studies were conducted with bigger sample size compared to the pilot testing and actual potential end-users from industry were recruited. The findings from Chapter 6 showed that the SPEXOR exoskeleton allows versatility and offers a significant support level. Although not directly compared with the Laevo system, the SPEXOR exoskeleton seems superior as tests showed more positive effects on objective and subjective performance in several load-handling tasks. Additionally, wearing the SPEXOR exoskeleton did not limit range of motion or hinder performance of tasks that require hip flexion. Thus, user satisfaction increased in comparison to the benchmark. Still, mass and dimension of the exoskeleton need to be adapted to improve comfort. In Chapter 7 , I assessed the effect of wearing the SPEXOR exoskeleton on metabolic cost during lifting. The findings showed that the SPEXOR exoskeleton takes over 25% of mechanical joint work, reducing muscular effort and hence decreasing metabolic cost by as much as 18% on average. This suggests that this exoskeleton is of benefit for lifting by decreasing physiological strain.