Biomechanical inverted pendulum: a model for initial testing of interaction controls

Abstract

Computational models of the neuromusculoskeletal system are useful for developing controls applied to rehabilitation robots. However, due to the high non-linearity, number of states and degrees of freedom, some models require a reasonable computational cost, making the development of controls slow, specially in the first stages. In this work we proposed the biomechanical inverted pendulum: a computational model of an inverted pendulum actuated by a set of four muscle-tendon and one linear coordinate actuator, presenting nonlinearities in both the mechanical and biomechanical parts, covering the problem of muscle redundancy and being less complex than a neuromusculoskeletal one. Such a model is expected to be useful for the development and testing of human-robot interaction controls in the first stage of the project. Two simulations with the proposed pendulum were performed: swing up and tracking movements. The results obtained with these two simulations proved that the biomechanical inverted pendulum is a feasible and useful model for the first tests with controls applied to biomechanical systems, allowing fast simulations and producing coherent results.