Sensorimotor Control of Biped Locomotion

Abstract

Human locomotion is extremely adaptive and robust to changes in environment, body size, and morphology. The control of this highly adaptive system is thought to be performed by central pattern generators, supported by a system of sensorimotor connections called reflexes. Several studies on central pattern generators have been conducted, alone and in concert with reflexes. However, controllers based on direct sensorimotor reflexes have not been given much attention, as they have probably been considered too simple for the task of controlling a biped. In this paper, however, we present results to the contrary. It is shown that a purely sensorimotor neural network, that is one with direct connections between sensors and motors can produce gait in an eight degree-of-freedom simulated lower body biped. Further analysis indicates that proprioceptive information is useful but not essential for the control of walking, while cutaneous information is essential. The final experiments show that sensorimotor control of biped walking can be accomplished using a network with only two cutaneous inputs and four neurons. The results suggest that reflexes may play a large role in rhythm generation, in addition to central pattern generators. The results also demonstrate the importance of sensorimotor reflexes in adaptive behavior.