Kinematic synthesis, optimization and analysis of a non-anthropomorphic 2-DOFs wearable orthosis for gait assistance

This paper describes the optimization of a planar wearable active orthosis for hip and knee assistance during overground walking. A non-anthropomorphic design is pursued in order to improve ergonomics and to reduce torque requirements. Based on a previously-developed systematic search algorithm of the admissible generalized solutions for the selected problem, a solution is selected and optimized by means of genetic algorithms and constrained non-linear optimization. The optimized design allows to conveniently redistribute mechanical power through different actuators, i.e. peak torque and velocity requirements for each actuator can be modulated, thus promoting a lighter design. A detailed analysis of the resulting mechanism workspace is carried out, including the evaluation of kinematic singularities, in order to verify the adequateness of the design in real-world scenarios. The developed model and optimization results are validated through a numerical analysis and experiments in a mock-up system.