To reduce the risk of low back injuries due to repetitive lifting in warehouse workers, an electric extender, composed of two arms and two legs, was designed and built for maneuvering boxes. During maneuvering large, rigid, and bulky objects, the device will let the wearer feel the forces as if they were the forces of maneuvering a light, single-point mass. This power extender not only can mask unwanted forces on the wearer, as in the last example, but also can be programmed to follow a particular trajectory regardless of the exact direction in which the wearer manipulates the extender. For example, suppose a wearer is using the extender to move a cylinder to its final destination. In this situation the extender can bring the cylinder to its final destination, moving the cylinder along a pre-programmed trajectory with a speed that is proportional to the magnitude (but not the exact direction) of the worker's force on the extender. In other words, in a situation where the wearer is paying little attention to the trajectory or to the final destination of the cylinder, the extender will still bring the cylinder to its final destination.

Electric Human Powered Extender - Arms

Electric Human Powered Extender - Legs