Trajectory Generation for the Leg of the Six-Legged Underwater Robot Over Obstacle in the Structured Terrain

As safe and effective underwater vehicle, underwater robot is considered to be an ideal tool for the investigation and exploitation in the large offshore area. There has been a growing interest to develop six-legged underwater walking robot for the researchers since the six-legged locomotion is more flexible and adaptable on the seafloor than other types of locomotion. The trajectory for the leg of the six-legged walking robot has a great influence on the locomotion quality and efficiency when the robot is a heavy one. The power consumed in the locomotion with different leg trajectories differs from each other greatly. Therefore, it is of great significance to study the trajectory of the leg. Of all the locomotion of the walking robot, crossing over obstacle is a typical one. Thus this paper mainly studies the trajectory generation for the leg of the six-legged walking robot over obstacle in the structured terrain. The robot has eighteen DOF and all the joints are hydraulically driven. In the current study, technical analysis is performed with the emphasis on the power consumption while crossing over obstacle. The analysis is conducted at various trajectories so as to compare the power consumed in different trajectories. Meanwhile, the study has also taken the smooth movement of the joint into consideration. The trajectory of the leg is theoretically analyzed and simulated. The kinematic simulation and the power consumed with different trajectories are both conducted in MATLAB. Simulation results have demonstrated the influence of trajectory on the power consumption of the robot while crossing over obstacle. The study has provided a theoretical way for the trajectory generation over obstacle for the six-legged walking robot.