Controller Design for an Inverted-Pendulum Model of Postural Balance with Delayed Proprioceptive Feedback

Abstract

Postural control during quiet standing is a challenging task for the neural controller due to the inherent instabilities involved in the task. Researchers have often employed inverted-pendulum (IP) type neuromechanical models to investigate postural balance in standing humans. In this study, we employ an IP-type robotic model with linear viscoelastic formulation of the skeletal anti-gravity muscles to study postural stability and control in the sagittal plane. The model includes delayed proprioceptive feedback from the muscle spindle and golgi tendon organ (GTO) with parameters drawn from physiological references. We propose a two-degree-of-freedom (2-DoF) internal model controller (IMC) for neural control of postural movements. We demonstrate the efficacy of the controller through simulations performed on the biomechanical model with realistic feedback latencies. We hypothesize that the closed-loop control system replicates the behavior of the physiological system during maintenance of postural balance.