Trajectory design and control of quadruped robot for trotting over obstacles

Various control strategies using trajectory planning, object recognition and learning are researched for avoiding obstacles when legged robot is walking. In this paper, designed trajectory by using Non Uniform Basis Spline (NUBS) curve and control strategy, by using proposed trajectory, to effectively overcome obstacles are presented. The trajectory designed by NUBS curve has several advantages: 1) local modification, 2) tracking velocity control for each domain, and 3) low degree trajectory with a large number of control points. The robot gets remarkable effectiveness when these advantages are used to generate the trajectory for walking and overcoming obstacles. By implementation of the proposed control strategy, quadruped robot can walk over obstacles while keeping its gait, speed and balance without collision although adjusting relatively preferable state which is more suitable position or posture of the walking robot shortly before encountering obstacles is not required. The proposed trajectory and control strategy are discussed, and performance is validated through experimental evaluations.