Depth Control of AUV Prescribed Performance Based on Backstepping Method

For the depth control problem of autonomous underwater vehicle (AUV), the goal is to improve its transient performance. Considering that the backstepping method only focuses on system stability but does not consider transient performance, while the prescribed performance control (PPC) requires introducing performance functions for each subsystem's error, resulting in a large number of control parameters and complex controller design. This article proposes a method that combines PPC with backstepping control. Only the angular velocity channel introduces a performance function for error transformation, and by selecting appropriate parameters, the depth channel's error will automatically satisfy a certain performance function. At the same time, considering external interference and model parameter perturbation, an adaptive rate was designed to estimate and compensate for it. The Lyapunov stability theory was used to prove the stability of the controller. Simulation results indicate that using this control method, depth errors will also satisfy the derived performance function. Compared to adaptive backstepping control methods, this approach has better transient performance while maintaining good system stability.