Fig. 5: The three distinct stages of the descending intruder.

a The experimentally measured trajectory at f = 3 Hz, Γ = 1.97, and g_env = 0.07 g. b The schematic diagram of the intruder’s motion in one step period. The orange dashed curve is the vibration of the container \({z}_{T}=A\sin (\omega t)\). The green dot curve is the intruder’s motion, and the blue solid curve is the motion relative to the container frame of reference, which is comprised of three time segments: the flight stage (from t_to to t_imp), the impact stage, and the stationary stage. The red dot represents the time of impaction, t = t_imp.