The amphibious bionic robot is an unmanned system which can work both underwater and on land, which has been widely used in the fields of disaster rescue, environmental detection and resource exploration. An amphibious robot compounded with wheel and fin with the ability of self-adaptive climbing was proposed in this paper. The kinematic and dynamic mechanics of the self-adaptive climbing process was analyzed. The torque required of the critical obstacle crossing point was set as the objective function, and the optimized design structural and operational parameters were obtained by applying the genetic algorithm. Meanwhile, the climbing ability of the amphibious robot in this work was compared with others. The results illustrate that the required torque of the amphibious robot was reduced by 718.4 N · mm. The robot compounded with wheel and fin can climb the vertical obstacle of a larger height. The self-adaptive climbing process of the optimized robot was simulated. The simulation results illustrate that the variation of the propulsive velocity, the displacement and the torque in the processes of moving forward and climbing the obstacles. The experiments of the obstacle climbing was investigated for verifying the structural and operational parameters design.

In order to improve the maneuverability and stability of underwater robots, a novel underwater robot driven by quadrotor and undulating fin was developed and its attitude control algorithm was proposed. The kinematics and dynamics model of cooperative propulsion by the propellers and the fin was established. The resistance coefficient was obtained by fluid numerical simulation. And the six-degree-of-freedom dynamic model of the robot was constructed. The attitude control strategy using hybrid drive of propellers and fin was proposed. A four degrees of freedom cascade proportional-integral-derivative controller and a control allocation algorithm were designed. The simulation model was established in MATLAB/Simulink software, in which pose curves in fixed depth cruise motion, heave motion and pivot steering motion were simulated and analysed. In addition, the influence of random interference on attitude control was simulated. Experimental results show that the robot has good attitude control performance. At the maximum undulating frequency, the attitude angle error of the prototype is less than ±4°; and the depth error is less than ±5 cm. The simulation and experimental results verify the feasibility of the novel underwater robot and the attitude control algorithm of propeller-fin cooperative propulsion.