Motion stability analysis of beaver-like robot

A stability index and evaluation method based on couple moment judgment are proposed for the motion stability of beaver-like robot. The index, expressed by the ratio of the recovery torque and external disturbance torque caused by gravity and buoyancy of the beaver-like robot, effectively evaluates the robot’s motion stability. The swimming stability index of beaver-like robot is calculated on the basis of Adams–Matlab co-simulation. Through comparative analysis of the indexes calculated in accordance with experimental and simulation data under different gaits, the stability of the robot in the rolling direction is confirmed to be worse under alternating gaits. The stability in the pitching direction is worse under synchronous gaits. Moreover, the increase of the motion amplitude of the propulsion structure (hind legs and tail) reduces the motion stability of the robot. This research can lay the foundation for stability criteria in underwater stable motion control and motion optimization of beaver-like robots.