Precise height control for UAV based on LADRC

Aimed at solving the impact of sophisticated wind disturbance, research on the control strategy, control structure and parameter optimization design is developed in this paper to realize height control with high precision performance in the longitudinal channel of unmanned aerial vehicle (UAV). First, based on the features of linear active disturbance rejection control (LADRC), the whole control structure is determined, and the probable disturbance from both inside and outside of the system can be estimated using the extended state observer (ESO). As a result, influence of disturbance on the output of the system can be eliminated by introducing this estimated value into the control law. Second, the power spectrum density of the wind turbulence and discrete gust are also analyzed, and a comprehensive fitness function considering impact of wind disturbance on height, characteristics of time domain response and stability margin is constructed, so that controller parameters with high precision and high disturbance-rejection performance can be produced through the particle swarm optimization algorithm to reduce the conservatism of controller parameter design. Finally, the outstanding performance of linear active disturbance rejection controller in the longitude channel of UAV is illustrated through being compared with the regular proportinal-integral-derivative (PID) height controller.