Impedance Control Analysis for Legged Locomotion in Oscillating Ground

The versatility of legged robots makes them essential for many inspection applications. However, these robots face significant stability challenges when maneuvering through difficult terrain characterized by rough surfaces or oscillations that challenge their stability. These challenges can arise due to different ground conditions, especially in oscillating environments such as offshore platforms, natural disaster areas, or seismically active areas. In this paper, we propose to analyze the impacts of the joint impedance control for legged robot locomotion on vibrating ground. Consequently, adjustments of the joints' impedance controller gains are proposed on the basis of an estimation of the ground frequency, obtained from kinematic measurements of the robot's legs. The simulation results demonstrate that an adaptation of impedance control gains in joint space can potentially improve the stability of the robot during full contact phase and while performing a walking trot over an oscillating terrain.