ADS Adaptive Backstepping Sliding Mode Depth Controller with Extended Observer

To solve the problems of model nonlinearity, disturbance uncertainties and unknown upper bound of disturbances in the process of atmospheric diving suit (ADS) motions in fixed depth, an ADS adaptive backstepping sliding mode controller with extended observer is proposed. The extended observer is used to observe the system disturbance, and tracking error can approach zero by controlling ADS depth through designed backstepping sliding mode controller. The Lyapunov stability criterion is used in proving the system stability and tracking error convergence when model uncertainties and external disturbance exist. According to the description and setting up of the designed control model, a series of tracking simulations were carried out. Simulation studies show that the proposed controller can well overcome factors such as model uncertainties and external disturbance, and has good robust performance, stability and tracking error convergence.