A spring-loaded inverted pendulum model for analysis of human-structure interaction on vibrating surfaces

Human-structure interaction (HSI) issues have gained increasing attention from researchers. In the present paper, a 3-D spring-loaded inverted pendulum (SLIP) model is established for modeling human running on vibrating surfaces. PD control for the leg force and foot moment is employed to achieve the desired values for the height and forward running speed of the center of mass, and P control is used to maintain limited lateral speed. Numerical results show the robustness of the control methods which are stable even subjected to large disturbances, and the effects of different control parameters are analyzed. Shaking table tests were conducted in which the participants ran on a treadmill excited laterally or longitudinally by a shaking table. The test results show that the HSI increased with the excitation level, and synchronizations were observed mainly in the cases of longitudinal excitations. The HSI can be interpreted as an equivalent additional mass and negative damping for the lateral direction, while additional mass for the longitudinal direction. The numerical simulations are compared with the experiments, and it demonstrates that the model describing human behaviors agrees well on both the stationary and moving treadmill (i.e. subjected to excitation).