Analysis of joint torque under single movement cycle of underwater legged robot

With the development of human exploration of the ocean, the movement ability of underwater detection equipment in the marine has become one of the key technologies that restrict the development of deep sea exploration and work. The underwater legged robot can achieve fixed-point operation and avoid disturbance from thrusters of ROV to the surrounding observation environment. In order to design and control the underwater legged robot, it is necessary to compute joint torque with influence of hydrodynamic force. This paper presents a method to compute joint torque of the underwater six-legged robot during movement cycle under different conditions. The method plans the motion trajectory of leg to get the motion parameters, and builds the dynamic equation of the leg with hydrodynamic force. At the end of the paper, an example were used to compute the joint torque under different flow direction and different flow velocity, and represents the results that only specific flow direction can influence specific joint.