Objectives  In order to determine the control method and recovery strategy for submarines falling deep underwater, a six-degrees-of-freedom motion model was established for an X-rudder submarine.

  Methods  First, the control rules of the X-rudder and the drainage capacity of the submarine were analyzed, and a recovery control system was designed using the fuzzy method. Second, recovery control in different degrees of depth scenarios was simulated in the course of large depth navigation, and the recovery control system was improved in both controller and control strategy. Finally, the recovery ability under different speed conditions was compared.

  Results   The results show that, on the controller side, the intelligent fuzzy integral link was introduced, improving the recovery efficiency and depth control effect. On the recovery strategy side, the original control strategy was optimized using pitch assisted and acceleration, improving the deep recovery ability.

  Conclusions  The results of this study show that the X-rudder fuzzy control system combined with the pitch assisted and acceleration recovery control strategy has a good recovery effect for dangerous situations at depth.