Design of an Elastically Suspended Backpack with a Tunable Damper

Walking with loads is a common task in our daily life, inducing a significant increase in energy expenditure and leg force. Previous work has proved that an elastically suspended backpack could reduce the energy cost of load carriage. However, for various application situations and populations, people have different biomechanical requirements corresponding to the accelerative load force sequence on carriers versus step cycle. This paper proposes an elastically suspended backpack with a tunable damper regulating phase of load movement to further affect leg force in walking with load. Tunable electromagnetic damper adopts generator or motor modes, providing tunable positive or negative damping coefficient, respectively, and thus regulates the phase delay of load movement ranging from 0° to 360°. Examples of long-time walking, heavy load carriage task and patients with chondral abrasion in their knees are listed to demonstrate the mechanism of this tunable damped elastically suspended backpack.