Walking Assist Strategy of a Hip Exoskeleton Based on Upper and Lower Limb Synergy Law

Aiming to facilitate walking assistance while avoiding interference with natural body movement and increasing user comfort, this paper proposes a novel walking assist strategy based on the law of upper and lower limb synergy and admittance control, which is applied to a designed hip exoskeleton. The hip exoskeleton is lightweight and designed not to restrict natural body movement. Two operating modes are developed: zero-torque mode and assist mode, both based on admittance control. In zero-torque mode, shoulder angle is collected via IMU and a radial basis function neural network, combined with particle swarm optimization, predicts hip joint angle. Once the synergistic law between shoulder and hip joints is established, the exoskeleton enters assist mode and utilizes this law for walking assistance. Finally, the experiment results demonstrate the effectiveness of the proposed strategy.