Depth Control of an Autonomous Underwater Vehicle (AUV) by Event-triggered Control Method

In this paper, a new method is used to depth control of an autonomous underwater vehicle (AUV). It is assumed that the desired trajectory, which should be tracked by the AUV, is defined by a user outside the vehicle and therefore, the communication between the controller and the AUV is done by a wireless network. To tackle the limitations and challenges in the wireless communication, a novel method is used to decrease the rate of sending messages from the controller to the actuator, while the closed-loop performance is maintained. To this end, using the nonlinear state-dependent Riccati equation (SDRE), a tracking controller is designed for the depth control of the AUV. Then, using the event-triggered methodology, the communication rate between the controller and the AUV is minimized. According to the mean square tracking error of applying both SDRE and event-triggered controllers, to track a damped sinusoidal trajectory ( and , respectively) and also according to 68 percent reduction of data transmission in event-triggered method, it can be concluded that the designed event-triggered control decreases the utilizing of the communication network with maintaining the system performance. Therefore, this method can tackle most of constraints and challenges of using a wireless network.