A Time-Independent Control Method for Variable-Speed Load-Bearing Walking with Suspended Backpack

Walking with a load brings a significant burden to human shoulders, resulting in increasing metabolic energy consumption and the risk of skeleton and muscle injuries. Suspended backpack has been widely conducted for load-bearing walking, but exiting time-dependent control methods and event-based control methods are unable to exploit the characteristics of human gait cycle. In this case, a time-independent control (TIC) method capable of eliminating the time dependence and adapting to variable speed is proposed. Based on the dynamical model of human-backpack system, an assistance profile along with the parameter optimization method are introduced which allows the backpack to reduce the burden on human shoulders during load-bearing walking. In the simulation evaluation, the proposed TIC method is compared with an impedance controller based time-dependent method and a locked backpack, under both constant speed and variable speed conditions. The results demonstrates that the TIC case achieves an $89.1 \%$ reduction in dynamic load on shoulder under the condition of constant speed and a $78.2 \%$ reduction under the condition of variable speed, compared with the LOCKED case.