Adaptive sliding-mode control of tri-speed torpedo

The motion characteristics of the tri-speed torpedo may vary in different speeds, and have different requirements for the adaptive ability and robustness of the control system. For this problem an adaptive sliding-mode control method is proposed. The vertical motion control is divided into two loops, the pitch angle control loop and the depth control loop. The depth control loop uses the adaptive algorithm to online estimate the angle of attack which cannot be measured. The pitch angle loop uses the adaptive sliding-mode control method, online estimates the uncertain model parameters and overcomes the unmodeled uncertainties, which ensures the stability of the tri-speed torpedo under the condition of speed change and model parameters uncertainty, and also eliminates the depth steady-state errors caused by the non-zero equilibrium state. The simulation results verify that the effectiveness of this adaptive sliding-mode control method.