Man vs Machine – Biomechanical legs gets an upgrade
The human gait has been tuned over millions of years of evolution to be as efficient as our anatomy allows. But technology is catching up, according to scientists in the United States.
A pair of biomechanical legs that accurately recreates human locomotion has been developed by scientists at the University of Arizona.
M. Anthony Lewis and Theresa Klein, researchers from the university’s Robotics and Neural Systems Laboratory, have published their findings in the Journal of Neural Engineering revealing the development of a highly advanced pair of mechanical legs that are able to mimic human walking in a “biologically accurate, energy-efficient manner.” The legs are intended for researching how humans learn to walk, but potential future applications include giving the ability to walk back to patients with spinal-cord injuries.
The scientists, of the university’s Department of Electrical and Computer Engineering, claim their biomechanical legs are the most advanced ever, and the first to accurately reproduce human gait characteristics.
The new legs can adjust for varying surfaces with the help of a small computer taking readings from load sensors in the feet, allowing the legs to mimic the up and down movement of human legs.
The legs consist of a copy of the human hip, knee and ankle controlled by nine “muscles”, which are in fact Kevlar straps that move up and down as required. The movements are determined by an electronic version of the central pattern generator (CPG), a neural network in the base of the spine which is semi-autonomous from the brain. The CPG gathers information from the body and responds to the environment accordingly. This is why humans can walk without thinking about it.
When the elements of the legs were combined with the electronic CPG, the legs were able to move in much the same way as a human. This was verified by comparing to data gathered in human studies, paying particular attention the movement at the hip and knee.
While other bipedal robots, perhaps the most famous of which is Honda’s ASIMO, are able to walk, run and even climb stairs, the energy required to do so is so great that battery life is a major limitation to their widespread use. This design is claimed to be the first which does so without using vast expanses of energy. The implications of this could include legs that could walk all day without recharging. This would obviously be a huge leap forward in the rehabilitation of spinal cord injury victims.
This development is an example of what Lewis calls “soft robots, which can be used around human beings”, continuing that “conventional robots derive their heritage from industrial robots and they are very stiff – they wouldn’t be safe around grandma. So this is a step in that direction.”
Where to from here? According to Lewis the next phase includes the addition of tactile sensors and vision capabilities “so that if you stumble, the system will correct itself and not fall over.” He went on to state that they have received interest in the legs from two major corporations and that they “are currently looking at transferring this technology to one of them.”