The Research And Realization Of The Large Airship Attitude Calculating Algorithm Based On SINS

With the development of large airship technology and the expansion of large airship application field, people want to find an airship attitude calculating system which is suitable for large airship s motion characteristics and also can measure the airship attitude accurately. As the attitude calculating system is the base of inertial navigation system and the first question need to be solved in the course of inertial navigation system work, the research and realization of the airship attitude calculating algorithm based on SINS has a certain practical significance.The large airship attitude angle is divided into the pitch angle, roll angle and heading angle. The traditional inertial navigation system is by doing integration for the angular velocity data output from the gyroscope, then to obtain the attitude angle of the aircraft. As any gyro output has drift, and this cannot be completely eliminated, with time going on, the accumulated error from it will become larger and larger. In addition, there are also using the accelerometer to assist in calculating the gyro attitude angle, however, in this method, if the airship has the horizontal direction acceleration or deceleration, there will have a large deviation for the angle value calculated from the acceleration s information. For the heading angle measurement, we usually use the electronic compass, but the deficiencies of this method is mainly reflected by these, there will be some change when the geomagnetic field affected by the environmental factors, and if we use the disturbed geomagnetic field strength to calculate the heading angle directly, there will exist a large error.Taking into account these above three aspects, this paper have made a thorough research on the big airship attitude calculating algorithm. First, analyzed the output signal of the accelerometer and gyro sensors, as there are more exotic data of the accelerometer output and lots of high-frequency noise in the gyroscope output, this paper put forward a singular point elimination algorithm based on the Kalman estimation, and designed a low-pass filter based on wavelet transform for processing the output data of the gyro. Second, the existing balance filtering algorithm combines the acceleration and angular velocity information, but did not analyze the conditions of the application of the acceleration, resulting in the accumulation errors and dynamic solver accuracy have not been addressed effectively, for these problem, this paper put forward an adaptive attitude calculating algorithm that have integration of the acceleration and angular velocity data, and this algorithm is according to the airships different motion states to adjust the attitude calculating algorithm. Finally, we analyzed the error existed in the measurement of large airships heading angle by the magneto resistive electronic compass, and put forward a heading angle error correction algorithm that based on the elliptical model.The experimental results show that this research work has effectively solved the existing lack of balance filtering algorithm, and achieved the accurate judgment on the big airships motion states by introducing the concept of SMV (Signal Magnitude Vector), and improved the accumulation errors of the existing algorithm and dynamic performance effectively. In addition, the heading angle compensation algorithm based on the elliptical model effectively correct the impact of environmental factors on the geomagnetic field, so that the heading angle calculation to achieve the expected results.