Attitude Consensus and Vibration Control of Flexible Spacecraft With Input Quantization and Asymmetric Time-Varying...

In this article, we investigate the problem of distributed boundary attitude consensus and vibration control for multiple flexible spacecraft with asymmetric time-varying output constraints, input quantizations, and unknown time-varying disturbances. The directed multiagent network consists of a time-varying virtual leader whose attitude is equal to the desired attitude consensus value and multiple spacecraft modeled by partial differential equations (PDEs). To rapidly observe the leader's state, an adaptive fixed-time distributed observer is first designed. Drawing on the observed desired attitude, a desired trajectory planning function is then defined. Combined with the disturbance observer method, we propose a novel distributed adaptive boundary output-constrained control strategy aimed at mitigating vibration deflections, compensating for quantization errors, and achieving consensus in attitudes. In this approach, barrier Lyapunov functions (BLFs) and trajectory planning functions are leveraged to ensure that the asymmetric time-varying output constraints are never violated. Based on the Lyapunov stability theory, the attitude tracking errors and vibration deflections of all flexible spacecraft are proved to be uniformly ultimately bounded. Finally, numerical simulations are conducted to demonstrate the effectiveness of the proposed control scheme.