Study on Autonomous Hovering of the Spherical Underwater Robot Based on Fuzzy PD Controller To make the movement of the spherical underwater robot more stable and easier to control, it is necessary to design a controller that can hover autonomously. According to the dynamic equation, we solved the transfer function of the spherical underwater robot in the dive process. Next, we designed the fuzzy PD controller which was easy to control, nonlinear and automatically adjustable. We used Simulink to build the hover motion simulation model for the spherical underwater robot, including using fuzzy PD controller and without fuzzy PD controller, and we carried out the comparative experiments of two simulation models. Then we applied the fuzzy PD controller to the hover motion of the spherical underwater robot, and carried out hover motion experiments. The experimental results showed that the fuzzy PD controller had better performance, and improved the stability of hover motion of the spherical underwater robot.

Design and Analysis of a Flyingcrawling Spherical Robot for Multimode Movement A novel spherical robot named flyingcrawling spherical robot is designed in this paper. It can fly or roll on ground with its single rotor and eight tail fins. When its limbs stretch out it can crawl on the supporting surface. Besides, with its limbs the robot can realize carrying objects, landing on uneven ground and walking on the supporting surface. Dynamic model of the robot in flight mode is established and the motion characteristics are analyzed. A PID control system is designed to enable the robot to achieve stable flight. Trot gait planning of the robot is given and a PID controller is designed for tail fins assistant in crawling mode. Corresponding simulations are carried out and the simulation results verify the proposed methods.