Energetic Response of Human Walking With Loads Using Suspended Backpacks

The suspended backpack is a wearable robot applied in load carriage to reduce the energetic cost of human walking or harvest energy and generate electricity. An essential problem in the control objective of the suspended backpack is the unknown energetic response of humans, which would affect the human walking cost and energy harvesting efficiency. In this article, we aim to figure out the human response to different patterns of relative load movement and provide high-level instructions for controlling the actively suspended backpack. The additional force induced by the relative load movement is characterized by two independent features: The impulse during the double-support phase, and the mechanical work over a step. We predict the human response to different combinations of these two features, with the results validated by experimental energetic cost versus phase of relative load movement, and compared to the empirical data from previous reports. The analyses suggest that the upward impulse during the double-support phase and inputting energy could reduce the energetic cost of humans, and the upward impulse and outputting energy could generate electricity with high-energy harvesting efficiency.