Saskia Baltrusch

122 Chapter 5 Several reasons are reported in the literature as to why back support exoskeletons and exoskeletons in general are not widely adopted in the industry yet: discomfort [23-25], excessive force application [23], loss of range of motion [10,23,26], not easy to use [24], kinematic incompatibility [24], long donning times [16], and lack of versatility to be used in a variety of real world settings [26]. To address these needs and to develop more suitable exoskeleton solutions, the SPEXOR consortium was formed. With the goal to develop and test, first a passive, and later on, an active exoskeleton for back support [27]. This paper presents the design and preliminary testing of a passive back support exoskeleton, that allows for a large range of motion of the lumbar spine and the hip and asserts kinematic compatibility with the user (Figure 1B). In section 2.1 the requirements which lead to the current prototype are discussed. The concept of the novel back support exoskeleton and its design are explained in section 2.2, with a focus on the elastic back support mechanisms. The mechanical implementation of the elastic back support mechanism, the misalignment compensating hip module as well as the passive torque source at the hip are described in section 2.3. Subsequently, the experimental testing of the components as well as the testing involving human subjects are elaborated in section 3. The outcomes of the component testing, biomechanical testing and functional testing are presented in section 4 and discussed thereafter in section 5. 2 Materials and Methods 2.1 Requirements An ideal back support exoskeleton can reduce the peak and cumulative loading on the back while at the same time still allow for a large range of motion. In order to be effective, a back support exoskeleton needs to connect the torso and the thighs. Due to the complexity of the hip joint and lumbar spine, many degrees of freedom need to be carefully bridged (Figure 2A). The kinematic compatibility and the fit of the device are tightly linked to the comfort of the user. Both characteristics are discussed in more detail in the following.