For the attitude control of diamond joined-wing unmanned aerial vehicle (UAV) with unknown external disturbances

the system has the characteristics of strong coupling

non-linearity

multi-input

and multi-output. Combining with sliding mode variable structure control theory

fractional calculus theory

adaptive control theory

new reaching law based on Fal function

and extended state disturbance observer

an adaptive fractional sliding mode control method was proposed. First

by introducing the fractional calculus theory and utilizing the genetic and memory characteristics of fractional calculus operators

the sliding surface of fractional calculus was designed to soften the controller output and control the overshoot of the controller. Then

in order to improve the weaknesses of traditional reaching law such as long convergence time and serious chattering

a new reaching law was proposed based on the Fal function

which could realize fast convergence without chattering. Finally

since there were modeling errors and external disturbances in the control system

the extended state observer was used to estimate and compensate the combined disturbance online. Simulation results show that the proposed control method had strong robustness and achieved ideal control effect.