Dynamic Modeling and Wave-Based PID Control of Rockets Considering Liquid Sloshing

The impact of liquid fuel sloshing in storage tanks during rocket flight and attitude adjustment cannot be ignored. In response to this research background, this paper conducted a coupled dynamic modeling of liquid rockets and proposed an improved proportional–integral–derivative (PID) control method based on wave theory, achieving efficient dynamic modeling and sloshing suppression. Firstly, a bouncing ball model for the liquid nonlinear sloshing in the Cassini tanks was established. By comparing it with the computational fluid dynamics method, it was demonstrated that the equivalent model can efficiently calculate the sloshing force, torque, and center-of-mass motion trends of the liquid. Secondly, based on the wave theory, an improved PID control method is proposed to achieve both target tracking and sloshing suppression simultaneously. Finally, taking the working condition of the liquid rocket attitude adjustment as an example, a rigid–liquid–control coupling simulation was achieved. By comparing with the traditional PID method, the effectiveness of the control method proposed in this paper was verified.