Human Walking Gait -- and, Its Potential Treatment Options -- Can Be Studied Using New Robot

A team of researchers from the University of Arizona has successfully produced a robotic set of legs, nicknamed Achilles, that they believe is the first to walk in a biologically accurate manner. The walking gait is remarkably human-like, largely due to neural architecture, musculoskeletal architecture, and sensory feedback pathways that are based off of humans, but simplified and built into the robotic legs. A key factor in the human walking system is the central pattern generator, or CPG, which is a neural network in the lumbar region of the spinal cord. This area of the spinal cord generates the rhythmic muscle signals need to walk. The CPG produces and controls the muscle signals by gathering information from the various areas of the body that respond.

CPG, in its simplest form, is what is referred to as a half-centre. The half-centre consists of two neurons that fire their signals alternatively to produce a rhythm. This rhythm is what allows us to walk without thinking about the action. In the robot, designers placed an artificial half-centre as well as the sensors that deliver the information back to the half-centres. One of the most important sensors is the load sensor, which senses the force that is in the limb when the leg is pressed against a stepping surface.

The researchers believe that babies begin life with a simple half-centre, similar to the one they placed in the robot. They hypothesize that over time the infant learns a network for more complex walking pattern. Past studies have shown that infants will exhibit a walking pattern when placed on a treadmill well before they learn to walk. With this theory, the reason for the walking gate in young infants would be owed to the half-centre that is already in place. The study was co-authored by Dr. Theresa Klein. According to Dr. Klein, "Interestingly, we were able to produce a walking gait, without balance, which mimicked human walking with only a simple half-centre controlling the hips and a set of reflex responses controlling the lower limb. This underlying network may also form the core of the CPG and may explain how people with spinal cord injuries can regain walking ability if properly stimulated in the months after the injury." View the short video below from the Institute of Physics:

Sources: iop.org/news/12/july/page_56499.html sites.google.com/site/rnsluofa/home popsci.com/technology/article/2012-08/rough-sketch-we-made-robot-moves-person Image sources: magmire.com kurzweilai.net popsci.com