Quadrotor's Active Disturbance Rejection Control Design And Implementation

With the intellectualization and miniaturization of the sensor,the cost of micro-controller is getting lower and lower,and the performance is becoming more and more powerful.Mature modern control theory and technology has promoted the development of quadrotor aircrafts.The quadrotor aircraft has so many features: Its mechanical structure is simple,its manufacturing cost is low,and it has the ability to stabilize the hover over the air.Therefore many research institutes are attracted to design its controller.The research on quadrotor is mainly divided into two aspects: theoretical research and experimental platform verification.(1)The theoretical study of the controller.The functional basis of the quadrotor is the attitude control technology.Nowadays,most of the open source flight controllers are PID algorithms.In order to seek better control effect,this dissertation introduces the Active disturbance rejection controller(ADRC).Firstly,the extended state observer(ESO)is analysed and the improved faln function is got based on improvement of the ESO's nonlinear fal function.The convergence of the improved ESO is demonstrated.Then,compared with traditional fal function,the improved faln function can obtain better effect of “big error,small gain”.Finally,the improved faln function is applied to quadrotor aircraft attitude,and simulation results show that the proposed function is superior to the traditional fal function on disturbance rejection.(2)Experimental platform verification.This dissertation sets up a dual-core controlled quadrotor physics experiment platform.The experimental platform embeds a small real-time operating system FreeRTOS to facilitate the extension and transplantation of future functions and to reduce the workload when modifying control algorithms.The attitude solution part and the controller part are respectively located in two processors,reducing the processing pressure of a single processor.The cascade PID control algorithm,PID and auto-disturbance rejection control algorithm are implemented on the quadrotor experimental platform.The angular velocity control data is collected from the inner-loop control test,and the angle control data is collected from the double-loop cascade control test.The two kind of effect are compared.The tracking effect and tracking speed of the control strategy of the inner loop using the active disturbance rejection control algorithm are better than the cascade PID control algorithm.