Geometry and Biomechanics for Locomotion Synthesis and Control

This paper summarizes two pieces of work related to human locomotion. The common hypothesis underlying these works is that human locomotion is characterized by, and possibly optimized to, the inherent mechanical and sensory-motor network structures. The first work investigates the effect of foot geometry on the walking speed and efficiency. Inspired from passive walk, we consider a foot shape with circular toe and heel segments, and optimize the gait for different toe and heel radii. We then compare the optimized gaits and demonstrate that round foot realizes faster and more efficient gaits. The second work focuses on the time delay of the human somatosensory reflex. Humans can walk robustly despite the tens of milliseconds of latency between the sensor input and motor output. To investigate how time delay affect the reflex model, we build somatosensory reflex models assuming different latency values and perform cross validation across multiple motions. The result shows that the network model using the physiologically realistic latency value better generalizes to a wide variety of motions, suggesting that the network is optimized to the inherent latency of the neural system.