Design of Longitudinal Flight Control System for Small UAVs

In the design of unmanned aerial vehicle (UAV) longitudinal attitude control systems, significant airspeed fluctuations are prone to occur, while existing research on UAV airspeed control remains relatively limited. This paper proposes an integrated altitude-hold and airspeed control system by incorporating fuzzy PID theory. System performance is enhanced through methods such as the introduction of open-loop zeros and adaptive control strategies. Additionally, the UAV's pitch control system is designed, and a comparative analysis of control effectiveness between fuzzy PID and traditional PID methods is conducted, thereby refining the UAV's longitudinal control system design. To validate system performance, simulations are performed using Simulink, with quantitative evaluation of key parameters including steadystate error and overshoot. The results demonstrate that the integrated altitude-hold and airspeed control system exhibits robust performance, effectively mitigating the issue of insufficient airspeed constraints in UAV longitudinal attitude control systems. The proposed integrated system optimizes longitudinal stability under dynamic flight conditions and provides a reference for subsequent UAV longitudinal control system designs.