Compliant curved beam transmission systems

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This report proposes a concept for an I-profile curved beam compliant transmission system. The application of this system can be as a hip connection within a passive exoskeleton in which it transfers the walking motion from one leg to another. To obtain the desired behavior the torsion stiffness is reduced and the amount of work needed to move the system is minimized, resulting in a reduction of 80%. Thereby, it provides a bending stiffness that is almost ten times larger than the torsional stiffness, offering support during bending and lifting movements. Replacing classical subsystems with compliant mechanisms offers opportunities for parts and weight reduction. A proof of concept prototype is obtained out of PA12 and the behavior is demonstrated in a series of experiments. These experiments are supported by a Finite-element analysis, which is also used to predict the behavior for different materials, geometries and applications. The validated concept is applied in a design case for the back support system of Laevo Exoskeletons.