Load-Transfer Suspended Backpack With Bioinspired Vibration Isolation for Shoulder Pressure Reduction Across Diverse Terrains

Active suspended backpacks represent a promising solution to mitigate the impact of inertial forces on individuals engaged in load carriage. However, identifying effective control objectives aimed at enhancing human carrying capacity remains a significant challenge. In this study, we introduce a novel approach by integrating a limb-like structure-type (LLS) bioinspired vibration isolator, modeled using Lagrangian mechanics, into an active load-transfer suspended backpack to primarily alleviate human shoulder pressure, thereby constructing a humanrobot interaction control framework for the system. Drawing from a double-mass coupled oscillator model, this approach formulates a vertical dynamics model for the human-backpack system, systematically exploring the principles of both static load transfer and dynamic load reduction on the human shoulder. Subsequently, a series elastic actuators-based controller with prescribed performance is proposed to simultaneously achieve trajectory tracking and ensure load motion within the limited range. Theoretically, we validate the input-output stability of the LLS model and guarantee the ultimate uniform boundedness of the closed-loop system. Simulation and experimental trials conducted across different terrain scenarios validate the effectiveness of the proposed method, highlighting reductions of 18.68% in metabolic rate during level ground walking, 9.58% in a staircase scenario and 12.35% in a complex terrain, involving uphill, downstairs, and flat ground walking.