Research On ESO Based Integral Sliding Mode Control Strategy For Quadrotor UAV

With the booming of robotics and artificial intelligence industries,more and more unmanned aerial vehicles(UAVs)have been applied to industrial activities and people's daily lives.The most representative one is the quadrotor.The quadrotor is drived by four propeller rotations,which is flexible and controllable.At the same time,the quadrotor UAV is also an underactuated,multivariable,and strongly coupled complex nonlinear system,The research on its modeling and control has important theoretical significance and application value.In this paper,the development status and research hotspots of quadrotor UAVs are analyzed in detail and extensively.Then take the quadrotor Qball-X4 in our lab as the research object,the dynamic model is established,and an ESO based integral sliding mode control strategy is proposed,mainly includes the following aspects:First,due to the under-driving,multivariable,and strong coupling characteristics of the quadrotor UAV,the acquisition of its mathematical model is difficult.This paper first researchs the five basic flight modes of the four-rotor UAV: hovering,lifting,pitching motion,rolling motion and yaw motion,and analysis the force and torque of the quadrotor by establishing the ground coordinate system and the body coordinate system.Then,the quadrotor's body is regarded as a rigid,and the nonlinear mathematical model is obtained by researching its dynamics and kinematics.Second,the ADRC attitude controller is designed for the quadrotor.Based on the analysis of the principle of tracking differentiator,the formula of the optimal control synthesis function of the system input is derived.Then the algorithm principle of the extended state observer is analyzed and the formula is derived.An attitude controller based on ADRC is designed by the decoupled model from each channel of the quadrotor.The effect of quadrotor UAV trajectory tracking using the designed ADRC controller and PID controller is compared by Matlab/Simulink simulation.Thirdly,combined with the idea of sliding mode control technology and ADRC technology,an integral sliding mode control strategy based on ESO is proposed.Firstly,the principle and characteristics of sliding mode control are analyzed.Aiming at the problem that SMC cannot provide robustness in the approach process,the idea of integral sliding mode control is introduced,and the formula of integral switching surface and integral sliding mode controller is derived.Aiming at the chattering phenomenon caused by too large coefficient of the switching surface sign function,an extended state observer is designed to compensate the total disturbance in the system to further improve the robustness of ISMC controller.The control effects of the LQR controller,the ISMC controller and the ESO-ISMC controller under additional interference conditions are compared by simulation.Fourthly,the flight experiments were conducted on the Qball-X4 experimental platform to verify the effectiveness of the proposed algorithm.