Research On The Flight Control Method Of Quadrotor UA

Quadrotors have been widely used in various fields because of their high agility and vertical takeoff and landing capabilities,such as aerial photography,search and rescue,explosive evacuation,etc.In many application fields,the use of quadcopter crane to transport and mount has always had great application value.However,due to the underdriven nature of the quadcopter,the design of the controller was often very challenging.Moreover,since the quadcopter and the mount are only connected by ropes,there is no actuator to control the swing of the mount,and the hanging and mounting on the quadcopter undoubtedly increases the underdrive characteristics of the entire system,coupled with its own nonlinear system,making the design of control a very challenging task.It has always been an open problem to make the quadcopter transport mount move along the desired trajectory while reducing the swing of the cable,and in the actual working environment,the mounting was also susceptible to external disturbances,and improving the robustness of the hanging system is essential in the safety of transport operations.In response to the above problems,the research content of this paper is as follows:(1)Based on the Lagrangian method to derive the linear model after decoupling of the hanging system,the linear controller has been designed by the linear quadratic matrix method,the integral of tracking error has been introduced into the QR matrix,and the integral sliding mode surface has been introduced to further enhance the robustness of the hanging system.(2)Taking the position and swing direction of the mount as the system state,the nonlinear model of the hanging system has been derived based on the Newton-Euler method,in order to optimize the convergence effect,a finite time convergence controller has been designed using the backstepping method,and the interference error has been introduced into the fractional power function of the tracking error,and the finite time interference observer based on multivariate superdistortion algorithm has been used to compensate for external interference and concentrated interference.The high-order derivative of the input has been estimated by using a third-order differential with finite time convergence,which solved the problem of virtual control input differential explosion caused by the backstepping method.(3)Based on the open source flight controller Pixhawk,an experimental platform of the hanging system for actual flight test was built to verify the performance of the designed control algorithm.The main changes were: created a custom flight mode for hanging flight experiments;Designed a 400 Hz serial port communication protocol for reading external sensor information;Created of a flight log for downloading flight data from ground stations;Added remote control mapping channel for switching flight modes;Mount attitude solving has been used for the controller to read state information,etc.