Human motion analysis in medical robotics via high-dimensional inverse reinforcement learning

Abstract

This work develops a novel high-dimensional inverse reinforcement learning (IRL) algorithm for human motion analysis in medical, clinical, and robotics applications. The method is based on the assumption that a surgical robot operators’ skill or a patient’s motor skill is encoded into the innate reward function during motion planning and recovered by an IRL algorithm from motion demonstrations. This class of applications is characterized by high-dimensional sensory data, which is computationally prohibitive for most existing IRL algorithms. We propose a novel function approximation framework and reformulate the Bellman optimality equation to handle high-dimensional state spaces efficiently. We compare different function approximators in simulated environments, and adopt a deep neural network as the function approximator. The technique is applied to evaluating human patients with spinal cord injuries under spinal stimulation, and the skill levels of surgical robot operators. The results demonstrate the efficiency and effectiveness of the proposed method.