Error Compensation For Inclinometer Of TBM Guidance System

Laser target guidance system is used for attitude angles measurement and automatic guidance in TBM. In this system inclinometer plays an important role in roll and pitch angles measurement. During tunneling in hard rocks, big random error of inclinometer is caused by great vibration of TBM. The measurement accuracy is unsatisfied. Researching on error compensation for inclinometer and un-stationary random signal process, a method based on wavelet filtering is put forward for error compensation of inclinometer.Firstly, based on the fundamental theory of wavelet analysis, a method of wavelet threshold filtering is put forward, combining signal extension and approximate coefficients extension. It's applied for error compensation of inclinometer. After analyzing the fundamental reason for edge effect in wavelet filtering, two methods are put forward to decrease edge effect. They are signal extension and approximate coefficients extension. The parameters of orthogonal polynomials extension of signal and approximate coefficients are optimized through simulation. And the filtering length is determined. Then simulation is made for several kinds of signal process, combining different signal extension and approximate coefficients extension methods. Comparing the simulation results, the filtering parameters based on signal characteristic are determined and the synthetic filtering method is obtained.In the final, it's conducted of the inclinometer measurement experiment in the condition of simulated vibration of TBM. The processed results of the experiment show that the proposed method is more effective and versatile than average calculation method used in the field and traditional wavelet filtering method. And the error is compensated less than 1mrad.