UAV Broken-Line Path Following under Disturbance Conditions

For the broken-line path following problem of unmanned aerial vehicles (UAVs), to enhance the ability to reject wind disturbance and reduce position error overshoot when a UAV turns in the switching position of a broken-line path, this paper proposes a novel UAV three-dimensional broken-line path following control system. The control system is divided into four linear active disturbance rejection control (LADRC) loops based on a novel proportional-integral extended state observer (PI-ESO), a guidance law based on inverse dynamic resolving method and the broken-line path switching methodology. For the LADRC loops, inspired by proportional-integral observer, integral terms are introduced to a linear ESO (LESO) and a novel PI-ESO is proposed. A parameter tuning method for the PI-ESO is proposed for engineering application according to the idea of bandwidth parameterization. The broken-line path switching methodology adjusts the ground speed of a UAV at the proper time and speed magnitude according to the direction of the UAV and the relative position between the UAV and waypoints. The process contains three stages: speed reduction at uniform acceleration, turning at a lower speed, and speed recovery based on a fuzzy logic controller. The simulations demonstrate the effectiveness of the proposed path following control system.