Assemblers at the Honda Motor Co. (Tokyo) plant in Sayama, Japan, are using a new contraption to eliminate the risk of repetitive-stress-related injuries. The walking assist device helps support bodyweight to reduce the load on an individual's legs while walking, going up and down stairs, or working in a semicrouching position. The Sayama plant builds a variety of Honda vehicles, such as the Accord sedan and the Odyssey minivan.

The 6.5 kilogram device is designed for people who are capable of walking and maneuvering on their own, but who can benefit from additional leg and body support while performing assembly tasks. It reduces the load on leg muscles and joints (in the hip, knees and ankles) by supporting a portion of the person’s bodyweight.

The ergonomic tool, which operates for 2 hours at a time with a rechargeable lithium-ion battery, has a simple structure consisting of seat, frame and shoes. Each leg has a motor.

An operator puts on the device by wearing a special pair of shoes and sitting on a narrow seat that resembles a unicycle. A mechanism directs the assisting force toward the user’s center of gravity. The ability to control the assist force in concert with the movement of the legs make it possible for the device to provide natural assistance in various postures and motions.

Honda engineers began working on the walking assist device 10 years ago. The R&D effort that created the ASIMO humanoid robot, including the study of human walking, provided them with insight that was used to develop the ergonomic tool.

During their research, the engineers developed a mechanism where the seat and frame follow the movement of the body and legs. Assisting force is directed toward the end user’s center of gravity, just as with human legs, which enables the device to provide assistance in various movements and postures.

The ergonomic tool supports a portion of an end user’s bodyweight by lifting the seat as the frame between the shoe and seat bends and extends, just like knees, with the force from the motor. As a result, the load on leg muscles and joints is reduced.

Natural walking is achieved by changing the amount of assisting force applied to the right and left legs through the control of two motors based on the information obtained though sensors embedded in the shoes of the device.