Adaptive simplified surge-heading tracking control for underwater vehicles with thruster′s dead-zone compensation

Remotely operated underwater vehicles are usually equipped with four horizontal thrusters that form an X-shaped actuation configuration. Yet, thruster ' s inherent dead-zone may possibly result in strong chatter of moment inputs and motion tracking of underwater vehicles. This paper proposes a twolayer cascade tracking controller together with a deadzone compensator, in order to achieve simplified and effective surge-heading control of underwater vehicles equipped with an X-shaped horizontal actuation configuration. For the sake of brevity, the surge and heading dynamics are firstly unified as a second-order dynamic system where the known and unknown parts are separated, respectively. Based on this model, a feedback linearization control law with a combined error measure is designed in the first-layer cascade system for the simplified dynamics tracking. Then, a reducedorder extended state observer without using any priori knowledge of uncertainties is utilized in the secondlayer cascade system to estimate the complex uncertainty of the dynamics. It is noted that this two-layer tracking controller has only two gains to be adjusted, ensuring a simple calculation and microprogramming. Subsequently, a dedicated dead-zone compensator is proposed for the X-shaped actuation configuration and the input-to-state stability of the whole tracking system is analyzed. Finally, comparative numerical cases are provided to demonstrate the adaptivity and robustness of the designed surge-heading tracking controller, i.e., up to 56% reduction of the maximum surge tracking error owing to this dead-zone compensator and less than 0.03(circle) of the heading steady state error against different initial states.

Automated summary

This paper proposes a two-layer cascade tracking controller and a deadzone compensator for simplified and effective surge-heading control of underwater vehicles equipped with an X-shaped horizontal actuation configuration. The first-layer cascade system is used for simplified dynamics tracking, while the second-layer cascade system utilizes a reduced-order extended state observer to estimate the uncertainty of the dynamics. Additionally, a dedicated dead-zone compensator is proposed for the X-shaped actuation configuration and the input-to-state stability of the whole tracking system is analyzed.