A Stability Criterion for Hybrid-driven Underwater Bladed Legged Robot Based on Capture Point Theory
The underwater bladed legged robot hybrid-driven by 8 thrusters and 6 blade legs can walk on seafloor and the surface of underwater structure.This paper aims at investigating the evaluation criteria of the motion sta-bility of this kind of robot,where the evaluation criteria is called as stability criterion.The existing stability cri-terions mainly focus on the robot that is driven by single mechanisms(legs),and not consider the hybrid-driven un-derwater bladed legged robot.Using capture point theory,we propose a stability criterion for hybrid-driven under-water bladed legged robot.Firstly,a hybrid-driven rolling inverted pendulum model that can reflect the dynamic characteristics of the robot is proposed,and the kinetic energy of the robot that the swinging legs are just touching the ground is predicted.Then,according to the maximum and minimum thrusts of the thrusters,we calculate the variation range of the expected capture point that can enforce the kinetic energy of the robot becoming zero,and the variation range is called as capture domain.Finally,the spatial relationship between the capture domain and the support domain can be employed to judge whether the robot is stable,and calculate the stability margin of the robot.Underwater experimental results show that the proposed stability criterion has better sufficiency and universality.
Hybrid-drivenunderwater bladed legged robotstability criterionunderwater rolling inverted pendu-lumcapture domain