The Study For Path Following of Robot Fish Based on ADRC

The multi-joint robot fish is often subject to unknown external and internal disturbances during path following in water areas. In this paper, a path following control method based on active disturbance rejection control (ADRC) is proposed for obtaining high-quality tracking effect. Combining the kinematics and dynamics equations of the three-joint robot fish, the model of error for path following is established in the Serret-Frenet coordinate system by setting the virtual mobile robot. Based on the introduction of expectation angle, the guidance of forwarding and steering control law are designed respectively. Then the second-order path following controller based on ADRC is established to improve the robustness and rapidity of the robot fish in the path following. For the control of such systems, a disturbance observer and related techniques have provided a powerful tool to dynamically estimate and compensated the diverse disturbances and offered desired control performances. The experiment shows that the method proposed in this paper enables the robot fish to follow the given path at around 3s, and the error of position maintained at positive or negative 0.1m. Compared with the conventional PID control method, the results show that path following controller based the ADRC can restrain overshoot very well and follow the given path quickly, resulting in an improvement of path tracking time and accuracy.