Mechanical Arm for Soft Exoskeleton Testing

Soft robotic exoskeletons offer multiple advantages in the field of motor rehabilitation and assistance with activities of daily living This paper reports the design process of a mechanical arm for upper-limb soft exoskeleton testing. The main requirement of the test bench was to simulate five degrees of freedom (DOF) of the human arm, and in particular i) shoulder flexion/extension, ii) shoulder adduction/abduction, iii) shoulder medial rotation/lateral rotation, iv) elbow flexion/extension and v) forearm supination/pronation. An additional requirement included the possibility to alternatively lock each DOF. The final concept was designed using Autodesk Inventor and it is composed of 32 parts, 18 of which were particularly designed for this application. Topological optimisation and Finite Element Method (FEM) analysis were performed to some custom components to obtain the final design. The final concept was manufactured by means of additive manufacturing of PLA (polylactic acid) and laser cutting of PMMA (poly methyl methacrylate) sheets. After testing and validation, the prototype was able to meet the desired requirements and it can be used for soft-exoskeleton testing.