Research And Design Of Heading And Attitude Measuring System Based On Small UAV

The heading and attitude measuring system is the important source of the information of flight parameters of flight navigation system of a small unmanned aerial vehicle(UAV), and it is the indispensable key component of a small UAV realizing autonomously flight. The system mainly measures course angle, pitching angle, roll angle, flight altitude and position coordinates et al the flight parameters. At the same time, it provides them for flight navigation system of UAV, so that the flight navigation system can timely monitor the flight status of the carrier and adjust the flight attitude of the carrier according to the posture parameters, and in order to ensure that the UAV can fly in accordance with the setting posture and routes.The system adopts inertial sensor based on MEMS technology and combined with other sensors that serve as measuring unit, and it uses the STM32 microprocessor as the center of processing data and system control. At the same time, through wireless communication module, it can timely send the measurement data to the ground station or PC. The system applies a wide variety of data fusion algorithms to calculate the information of flight parameters. First of all, so as to form a digital cosine matrix, it calculates course angle, pitching angle and roll angle by using gyroscope data and Euler Angle algorithm. Secondly, so as to form a three dimensional vector, it calculates pitching angle and roll angle by using the accelerometer data, and it parses out the course angle by using GPS data. Thirdly, it compares the three dimensional vector with the course angle and attitude angle calculated from the digital cosine matrix, and it concludes the angle errors. At the same time, according to the angle errors, it applies proportional plus integral controller to compensate the course angle and attitude angle calculated from gyroscope timely, so that the orthogonality of the digital cosine matrix is not destroyed. Therefore, according to the digital cosine matrix, it can get more accurate course angle, pitching angle and roll angle. In addition, the system calculates the height by applying the digital barometric altitude sensor and barometric altitude formulas.First of all, this paper introduces the status both at home and abroad of the subject and the related background knowledge, as well as the research scope and the main content. Secondly, it makes the instructions about the theoretical basis of knowledge and the relevant algorithm of heading and attitude that the system involves, and they mainly include the reference frame that the system commonly uses, the decoding algorithm of barometric altitude, direction cosine matrix, Euler Angles algorithm, the principle of inertial measurement and the principle of GPS measurement. Thirdly, this paper introduces the hardware design and software design scheme of the system. Finally, through the combination of hardware circuit and software program, it designs a heading and attitude measuring system that can work normally, and it obtains the related measurement results by experiment. The experimental results show that the system has reached the original design goals and requirements, and the outputs of the course angle and attitude angle are stable and have a high precision. At the same time, the errors of the outputs are acceptable. The system can be used in the flight control system of a small UAV.