Engineering in Motion
Researchers in Carnegie Mellon University’s College of Engineering are using feedback from the human body to develop designs for exoskeletons and prosthetic limbs.
Published in Science, their technique, called human-in-the-loop optimization, customizes walking assistance for individuals and significantly lessens the amount of energy needed when walking. The algorithm that enables this optimization represents a landmark achievement in the field of biomechatronics.
“Existing exoskeleton devices, despite their potential, have not improved walking performance as much as we think they should,” said Steven Collins, a professor of mechanical engineering. “We’ve seen improvements related to computing, hardware and sensors, but the biggest challenge has remained the human element — we just haven't been able to guess how they will respond to new devices.”
The software algorithm is combined with versatile emulator hardware that automatically identifies optimal assistance strategies for individuals.
During experiments, each user received a unique pattern of assistance from an exoskeleton worn on one ankle. The algorithm tested responses to 32 patterns over the course of an hour, making adjustments based on measurements of the user’s energy use with each pattern. The optimized assistance pattern produced larger benefits than any exoskeleton to date, including devices acting at all joints on both legs.
“When we walk, we naturally optimize coordination patterns for energy efficiency,” Collins said. “Human-in-the-loop optimization acts in a similar way to optimize the assistance provided by wearable devices. We are really excited about this approach because we think it will dramatically improve energy economy, speed and balance for millions of people, especially those with disabilities.”