Virtual modelling of a real exoskeleton constrained to a human musculoskeletal model

Exoskeletons represent one of the most important examples of human-oriented robotic devices. This paper describes an existing lower-limb exoskeleton designed to assist people with lower extremity paralysis or weakness during the movements of standing up and walking. Starting from the analysis of a real system developed about seven years ago, a virtual multibody model was realized in order to deeply understand how the device worked and find out some potential improvements in the actuators control and in the kinematic design. The virtual device was properly constrained to a human musculoskeletal model in order to simulate a real operating condition. The analysis of the simulation results suggested a kinematic modification of the system and a new dynamic model was developed in order to test the new design through the comparison of four different models.