Study Of Control Technology And Design Of Low-power System For Quad-rotor UAV

Rotor UAV is of great attraction because it can take off and landing vertically, flyin low-speed, hover and the flight speed is able to be directly controlled by motorspeed. Besides, other advantages such as relatively low manufacturing costs and betteradaption to the complex meteorological and geographic environment all contribute toits popularity. However, the problems such as low effective payload, short flight lifeand difficulties in control have confined its application. Therefore, it is of greatsignificance to study the control system to make it meet the needs of disastermitigation, relief work and battlefields.This thesis conducts a comprehensive study on the quad-rotor UAV, analyzingand establishing a mathematical model of its control system and at the same time,working on a sliding mode controller (SMC). Based on that, a quad-rotor UAV controlsystem and its flight simulation experiment platform is provided with the advantagessuch as a relatively longer flight life, lower power consumption, higher robustness,shorter adjustment time, better controllable flight position, attitude and height.The procedures and main findings of this thesis conclude:Firstly, through the comparative analysis of other cases, quad-rotor UAV issimplified into an underactuated system of six degrees of freedom and four inputs.The output of six degrees of freedom and four inputs of the system couple closelywith each other, increasing the difficulty of modeling and confining the application ofvarious control algorithms. In this thesis, based on mechanism modeling and kineticequation, a simplified quad-rotor UAV mathematical model is derivated andestablished and it laid a foundation for the control algorithm research.Secondly, based on the dynamic model of an aircraft, quad-rotor UAV’s PID andsliding mode control simulation platform are built by using MATLAB/Simulinksimulation software, simulating the position, attitude and height of the aircraft. Theresult manifests that the response time of PID control algorithm is about2secondsand sliding mode control algorithm, about1.6seconds. By comparing these twoalgorithms, it indicates that though PID algorithm can control the aircraft very well,the greater overshoot appearing during the control process makes a tortuous path forthe aircraft form the starting point to the destination; while sliding mode controlalgorithm can provide a relatively stable flight path with a shorter response time andbetter robustness. Next, through detailed analysis of the system functions and technicalrequirements, based on the constraints of low power consumption, this thesis, bydiscussing the main controller, the altimeter, gyroscope, wireless communicationmodule and the function and selection principle of executive motor, demonstrates aflight simulation platform program, gives a system diagram with AVR microcontrolleras the core and designs a corresponding circuit module diagram. The experimentsshow that the aircraft eventually reached the attitude control requirement under theconditions of a basic hover and auxiliary remote control.In the end, in terms of software design, modularization and structured design areadopted to design the control system software of the quad-rotor UAV. Low powerdesign is studied from system program, hardware and software design to summarizethe principles so as to elaborate the process and focus on the function modules ofself-diagnosis, which can increase the debug and maintenance of the system. Besides,main program and subroutine flowchart are also designed.