A Control System Design Of Small Unmanned Helicopter Based On Active Disturbance Rejection Control Technology

The small unmanned helicopter has unique characteristics such as low altitude flight and ready to take off and landing at any time,so it has been widely used in military and civil applications.As the helicopter is a nonlinear,strong coupling,complex aircraft,and in common,the helicopter is very easy to be affected by changes of temperature,wind and other environmental factors during the flight.Thus the development of the unmanned helicopter flight control system has a lot of problems.First of all,helicopter is a complex and a nonlinear system.It is hard to build a precise mathematical model of the helicopter,so many control algorithms in modern control theory are difficult to apply to the flight control of small unmanned helicopter.Secondly,there is a strong coupling of each channel in the helicopter,which increases the difficulty of design of the control system.Finally,there are many uncertain factors in the flight test,which will directly affect the safety of flight test.Firstly,according to the characteristics of small unmanned helicopter above,this paper builds a mathematical model of the unmanned helicopter based on the helicopter flight dynamics;deeply analyses the mechanics relation and motion equation of small unmanned helicopter inside,and gets a simple mathematical model of the small unmanned helicopter.Next,this paper established a small unmanned helicopter flight control system based on the series active disturbance rejection controller(ADRC),achieve the controller design of longitude,latitude,yaw,and height channel,improves the ESO algorithm of the ADRC,which eliminate vibrate that the original ESO algorithm have,overcoming a variety of unmanned helicopter control of small disturbance factors and coupling between channels,achieve the decoupling control of small unmanned helicopter.Then this paper simply introduces the flight control system,and its communication protocol;use C++ language to finish the flight control program in the control system based on the algorithm above;and write a ground station software in the control system,so that it can be apply to the real system.At the end of this paper,flight control system built on ADRC controller is compared with traditional PID controller.The simulation results show that the system built on ADRC can decouple each channel better and the system built on ADRC have a better result compared to traditional PID flight control system.After the simulation of the mathematical model,the software of the ADRC controller is verified by FlightGear,and the rationality of the algorithm and the software is proved,which provides the basis for the practical application of the system.