Study On Adaptive Dynamic Inversion Control Of Hexacopter Based On Pixhawk

Hexacopter has been rapidly developed. It has been used to deal with dangerous works for the sake of people's safety in many cases because of its flexiblility, autonomous flight and other characteristics. And its control system is particularly important to keep flying stably and deserves our minds to research.This article aims to study the flight control system of hexacopter based on Pixhawk which is one of the most famous open source hardware and software flight control system. The first part of the paper briefly describes the basic structure of hexacopter, and explains some key components specification, and then discusses the basic control principle of cross type hexacopter. The second part reveals the composition and control mechanism of Pixhawk flight control software. At first, this part introduces the overall framework of the system, selects one of the flight control stacks, builds compiling environment and simply analysis the flight control stack's compiling process. And then it describes APM's directory structure and the function of each library, and explains how each library functions are called in order. After that, it comes to its most meaningful discussion and core of flight control system, namely attitude estimation algorithm(DCM& EKF) and the law of flight control. It sorts out the mechanism and running procedure of DCM and EKF algorithms, and illustrates several flight control modes in APM. In the last part of the paper, nonlinear dynamic equation of hexacopter is established based on Newton's laws of motion. And a SIMULINK dynamic inverse attitude control simulation program is built. Finally, in order to enhance the robustness of the control system, an adaptive dynamic vector is provided, which is used to estimate and compensate the inverse model error of hexacopter.