Effect of considering sensors and actuators modeling on the design of PID controllers for an Autonomous underwater vehicle

This paper presents the effect of sensors and actuators modeling on the design of PID controller for an Autonomous underwater vehicle (AUV). In order to investigate the effect of those modeling on the behavior of AUV, a PID control scheme is developed by considering two different models, i.e., with sensors and actuators modeling which is called actual model and without those modeling which is called typical model throughout the paper. The PID controller is intended to control depth and head motion of 6-DOF nonlinear AUV model. In first stage, simulations of both models by assumption of same values for gain controllers are conducted. Their results reveal that considering the actual and typical models by same controllers, leads to unacceptable AUV´s manner and modification of controllers would be inevitable. In second stage, simulations are accomplished based on the new modified controllers which the results lead to the satisfactory manner of the AUV. Therefore, Simulation results prove that by incorporation of sensors and actuators modeling, the AUV´s behavior would be tolerated extreme changes even to the border of instability and thus it demands proportional modifications for the controller design to remain stable. Prototype vehicle called KAVOSHGAR has been designed at the Subsea Science & Technology Institute of the Isfahan University of Technology and its dynamics model based on the KAVOSHGAR´s coefficients has been established.