Attitude Stabilization Control Method for Quadrotor UAV Based on ADRC

Discrete ADRC method based on improved fal function and its application

“…Set 𝑑 11 = 1, 𝑑 22 = 𝑑 23 = 𝜆 , 𝜆 be an infinitely small positive number, then satisfying Lemma [1], combined with equations ( 7), (8), and (10) can be obtained: (11) Combining equation ( 9), it can be obtained:…”

“…The extended state observer can observe the state variables and unknown disturbances of the system, and its observation accuracy directly affects whether the system can effectively estimate the disturbances; in addition, the output of the nonlinear state error feedback control law directly acts on the controlled object, and its output quality directly affects the control performance of the system. For the research of the fal function, reference 7 7 proposed a faln function to improve the extended state observer and improve the anti-disturbance of the system, but did not solve the problem of high-frequency jitter of the system; reference 8 8 constructed a glan function to improve the extended state observer, which reduced the difficulty of parameter adjustment and improved the anti-disturbance of the system, but the function still had inflection points; reference 9 9 proposed a zzxfal function to improve the nonlinear state error feedback control law to overcome the unsmooth characteristic of the fal function and reduce the number of jitter in dynamic regulation, but the gain is still large when the error is large; reference 10 10 proposes a nfal function to improve the extended state observer and the nonlinear state error feedback control law, which improves the rapidity, anti-disturbance, and robustness of the system, but the function is too complicated. However, there are few kinds of research on the effect of noise on the ADRC system, and the actual controlled objects are generally discrete systems, and the traditional discrete ADRC methods are not applicable 11 .…”