A decoupling three-dimensional motion control algorithm for spherical underwater robot

Underwater spherical robots are good assistants for ocean exploration, where motion control algorithms play a vital role. Conventional motion control algorithms cannot eliminate the coupling relationship between various motion directions, which will cause the motion control of various directions to interfere with one other and significantly affect the control effect. This study proposes a new decoupling motion control algorithm based on the robot attitude calculation for an underwater spherical robot designed for offshore, shallow water, and narrow terrain. The proposed method uses four fuzzy proportional–integral–derivative (PID) controllers to independently control the robot's movement in all directions. Experiments show that the motion control algorithm proposed in this study can significantly improve the flexibility and accuracy of the movement of underwater spherical robots.