Research On Fractional Order Sliding Mode Control System For Four Rotor Unmanned Aerial Vehicle

Quadrotor UAV can perform takeoff and landing,hovering and other operations in situ,so it is widely used in daily life.However,the quadrotor aircraft system is complex and vulnerable to interference,so new requirements are put forward for the control of UAVs.The fractional order calculus operator has a certain memory,so this paper redesigns the fractional order controller of the quadrotor UAV by using this characteristic of the fractional order integral operator.The control structure adopts the internal and external loop cascade control,and in-depth research is carried out for the problem of the variable load of the airframe mass.The simulation experiments show that the designed controllers can meet the experimental requirements,Effectively improve the trajectory tracking control quality of quadrotor UAV.Through a large amount of work on the topic selection,the core idea of this article is determined based on the pain points of current research.The main research contents include:Under micro angle flight,the dynamics model of quadrotor UAV based on Newton Euler method method is established.The characteristics of the model were analyzed,the control objectives of the controller were clarified,and a schematic diagram of the control process control principle was drawn.When designing the sliding surface of the controller,a new fractional order sliding mode controller is designed by introducing the fractional order reaching law,combining the integral sliding mode and the fractional order integral operator,and the sliding mode parameters are adjusted using the particle swarm optimization algorithm.Through simulation experiments,the expected trajectory tracking effect of quadrotor UAV is compared.By comparing the fractional order controller with PID controller and integer order controller in experiments,it can be verified that the controller improves the response speed and robustness of the system.Then,the hybrid algorithm is used to re optimize the parameters of the fractional order sliding mode controller,further improving the controller,and comparing the trajectory tracking effect before and after the improvement through experiments,it can be verified that the hybrid algorithm can effectively improve the performance of the controller.Because the dynamic model of UAV is closely related to the mass,it will be disturbed by this factor in the natural state,so two kinds of adaptive sliding mode controllers are designed using two control methods.The first control concept is to convert the mass constant value into a time-varying function and estimate it using an adaptive law.The second control concept is to establish fuzzy rules in the controller,select appropriate membership function,and adjust the coefficient of the switching term of the sliding surface,so as to achieve high-quality control of the controller.Both types of controllers have passed experimental verification,and the results show that the controller can meet the experimental requirements,that is,the tracking of the desired trajectory is still stable under variable load conditions.