Humans have evolved to run with remarkable adeptness on undulating, natural terrains, a feat that is challenging for even the most sophisticated robots. Uncovering the fundamental principles that underlie our locomotion capabilities has significant impact on our understanding of human evolution and on the design and control of robots, prostheses, and sportswear. However, there are no overground running experiments on undulating terrains that measure how humans run on terrains which resemble those found in the natural world.

We designed an experimental setup using custom-built undulating terrains and conducted human-subject experiments these rough terrains, as well as flat ground. Along with increases in energy expenditure and small changes to stepping kinematics, we find that all subjects very tightly controlled the fore-aft impulse upon landing to reduce scuffing collisions, consistent with the results of our model. Maintaining compliant knee and ankle joints upon ground contact is key to reducing scuffing collisions. We find no evidence for path-planning strategies. This stands in contrast to the heavy use of path-planning strategies utilized by robots for walking and running. Our results are consistent with earlier animal studies of running stability on flat and step-like terrains, and further expands on the prominent role played by intermittent sensing and anticipatory strategies (in the form of controlling scuffing collisions) in maintaining stability.

Most recent conference publication (Adaptive Motion of Animals and Machines, 2019) : How humans run on rough terrain