| With the continuous development of automation technology and artificial intelligence discipline,the technology of multi-sensor fusion navigation is becoming more and more mature.Researchers have applied it to the field of robots represented by UAV,resulting in the flight control of UAV more intelligent and stable.Since the21 st century,UAV,as a typical representative of intelligent robots,has become more and more intelligent in its working process with the continuous improvement of hardware technologies such as processors and sensors.The increasing demanding for UAV has further promoted researchers and engineers to develop UAV.So far,the fixed-point hovering of UAV using satellite navigation technology has non-negligible error,and it is difficult to achieve stable hovering in a fixed area.Besides this,the optical motion capture system has also been applied to achieve fixed-point hovering of UAV.However,this method is only suitable for indoor environment where cameras are easy to deploy and the light intensity is not too high.The flying of UAV was restricted to the range captured by the camera.The birth of optical flow sensor provides a new solution to the fixed-point hovering problem of UAV.The positioning accuracy of optical flow sensor is higher than that of satellite navigation technology such as GPS,and the actual price is much lower than that of optical motion capture system.It is suitable for the application of consumer UAV and realization of cluster flight UAV system.In this thesis,based on the existing Four-rotor UAV technology and the new optical flow sensor measurement technology,the fixed-point hovering function with high accuracy will be realized.Firstly,this thesis will start with the basic flight principle of the Four-rotor UAV,explain the basic structure and components of the Four-rotor UAV in detail,determine the flight mode of the Four-rotor UAV,establish the dynamic model and mathematicalmodel of the Four-rotor UAV.Secondly,the selection of blades and motors will be determined,and the corresponding electric adjusting circuit will be designed.STM32F411RET6 will be used as the main control chip.Then,the fusion navigation scheme of sensors including MPU9250 inertial sensor,BMP280 high-precision barometer,PMW3901 optical flow sensor and VL53L0 X high-precision laser ranging sensor will be used.design the program of power supply circuit,download and debug circuit,and determine the selection scheme of wireless communication module.Therefore,the PCB frame is designed and drawn,the installation and debugging of each part of the Four-rotor UAV are completed,which can build the hardware platform of the Four-rotor UAV.Finally,starting with the software algorithm,the realization methods of various algorithms including inertial navigation,quaternion,second-order IIR low-pass digital filtering,complementary filtering and PID controller are described in detail.The dynamic process of fixed-point hovering flight of Four-rotor UAV is also introduced.At the same time,a simple verification experiment is designed to verify that the Four-rotor UAV studied and designed in this paper have a certain accuracy of fixed-point hovering function.The fore-four-rotor UAV studied in this thesis gives a new solution and lays a preliminary foundationfor the future application of multi-sensor data fusion technology in the field of UAV navigation. |
