Measurement Foundation of Railway Track Geometrical Parameters Based on Strapdown Inertial Technique

In order to found the datum plane of measurement of railway track geometrical parameters, a method to found the datum plane based on the strapdown inertial technique was researched to overcome the shortcomings of the traditional gyro platform. By analyzing the basic cant measurement principle, it was pointed out that attitude matrix calculation with a high accuracy is the key to the measurement of railway track geometrical parameters based on the strapdown inertial technique. Therefore, corresponding attitude, position and velocity differential equations for a train were founded based on the motion theory of rigid body. With a method based on rotary vector and quaternion, the calculations of attitude, position and velocity were analyzed and studied, and the multiple-sample algorithms were utilized to compensate for coning motion errors in attitude calculation and sculling errors in velocity calculation. The simulation results show that the multiple-sample algorithms are able to strongly decrease the accumulative errors with time in an inertial measurement system and improve the accuracy of a measurement system.