Several power assist robots have been developed to reduce workloads, and address worker shortages and an aging workforce. Previously, the authors developed a power assist device to maintain shoulder posture using a braking mechanism; however, the device presented technical issues regarding the rigidity and weight of the mechanism. To address these issues, in this study, a flexible linear brake (FLB), a brake mechanism driven by negative pressure, was developed for power assist devices. Additionally, a braking force model for the FLB is proposed; the proposed model was verified by comparing the measured and modelled values. Finally, a shoulder assist device that uses the FLB and designed based on the proposed model is discussed in detail.

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