Dynamic modeling and decoupled control of linear and angular velocity for robotic fish

Autonomous submarine robots are significant over the last decades. Since they can replace humans for performing dangerous underwater works. Positioning navigation is the key to guaranteeing that underwater robots can complete their task. The purpose of this paper is to control the linear and angular velocity of fish robot, to convert the robot model to unicycle model for mobile robots, which is make it possible to implement the navigation algorithm on robot. The appropriate dynamic model was simplified as a two dimensions model of robotic fish. Among different types of actuations, the tail-actuated robotic fish or BCF was considered. Also the average model of robotic fish was considered to control and its coefficient was corrected. The parameters of tail-actuating are defined as bias, amplitude and frequency. The frequency of tail-actuating was assumed to be constant but, bias, and amplitude are variable and controllable. After simulation the relations between tail-actuating parameters and rigid body linear and angular velocities was investigated. With this significance linear forward velocity and angular velocity could be controlled simultaneously and independently. This motion control applied on smooth rotation behavior with the constant speed, but it could be generalized for the others robot’s behavior. Eventually, through the amplitude, and the bias control respectively, the linear forward velocity is controlled with PI controller and 1.67% error and angular velocity is controlled with PID controller and 2.5% error.