Distributed formation control for multiple QUAVs with independent output constraints and actuator amplitude/rate saturation

This paper proposes a control strategy for distributed formation tracking of multiple quadrotor unmanned aerial vehicles (QUAVs) under output constraints, actuator amplitude and rate saturation, and unknown disturbances. Firstly, an error-separated universal barrier Lyapunov function (ESU-BLF) is developed. Unlike traditional barrier Lyapunov functions (BLFs), which restrict the overall formation error, ESU-BLF imposes constraints on multiple independent errors between adjacent QUAVs. This enables a more precise constraint effect while preventing the cancellation of positive and negative errors among QUAVs. In addition, ESU-BLF employs a prescribed performance function with infinite initial values, which resolves the constraints imposed by BLFs on the initial positions of QUAVs. To address the actuator saturation problem, a high-order adaptive auxiliary system is introduced to compensate for both amplitude and rate saturation. For unknown disturbances, a fixed-time disturbance observer is introduced, enabling rapid tracking of disturbances without assuming that the time derivatives of the disturbances are bounded. Lyapunov stability theory analysis proves that all system states and control signals are semi-globally uniformly ultimately bounded while guaranteeing prescribed output constraints. Comparative simulations demonstrate the effectiveness of the proposed control strategy.