Limit protection systems for safety operational envelope of submarine

To enhance the operational stability of submarines, this study conducts a comparative analysis of three pitch limit protection systems based on the reference model, potential function, and dynamic trim algorithm. The proposed depth limit protection system adjusts the depth command by comparing the desired depth, calculated by the outer-loop controller, against a predefined depth limit. Similarly, the pitch limit protection systems modify the command pitch calculated by the inner-loop controller to ensure it does not exceed the pitch limit. Submarine maneuvering simulations were conducted to verify the performance of the envelope protection system, which comprises depth and pitch limit protection systems. Simulation results confirmed the effectiveness of these methods, with the dynamic trim algorithm demonstrating superior control efficiency. This study advances submarine safety and stability by developing and validating advanced pitch limit protection systems.