Disturbance feedforward compensation based on Modelica modeling with the Self-immunity study of a quadrotor UAV

Abstract

Due to the nonlinearity, underactuated, strong coupling, multi-data flow direction, and vulnerability to internal and external disturbances, the widely used PID control technology has been very difficult. Some emerging nonlinear control theory algorithms have good simulation performance, but they rely heavily on exact mathematical models, require a large amount of computation, and take a long time to solve. Therefore, based on the advantages of non-causal declarative modeling in Modelica language, this paper focuses on the analysis and implementation of the mechanism of observation, estimation, and compensation of nonlinear ADRC disturbances, PID-NLADRC linear nonlinear combined control strategy is designed to realize the flight control of a four-rotor UAV. The multi-target applications, such as fixed-point hover, cone spiral trajectory tracking and air obstacle avoidance fillet moment trajectory tracking, are verified respectively. The simulation results show that the designed PID-NLADRC control strategy has better performance than the Cascade PID control strategy in suppressing the fixed-point hover disturbance, it is fully verified that the PID-NLADRC control strategy has a smaller Euclidean range deviation and stronger disturbance rejection ability for tracking trajectories with different properties such as plane or space, smooth or transient, it can better meet the requirements of fast, accurate and robust flight control of four-rotor UAV.