Characterization Of Non-orthogonality Attitude Position Error

Accurate measurement of small-angle attitude is the basis for vertical oil drilling.It’s a further increase for oil drilling on whole range of angles.The position errors of the attitude measurement system have a great influence on the output.Underground attitude information,as the main parameters for real-time closed-loop of downhole drilling control,will have a huge impact on the next drilling direction.Drilling technology,vertical drilling tools and measurement methods at home and abroad are briefly introduced,and the direction cosine method of the updating attitude algorithm is presented in detail.The paper makes sense of the basic principles of attitude measurement,deduces the output formulas of sensors with triaxial accelerometer,analyzes the output signal law of accelerometer,and studies the conventional calculation method of attitude measurement parameters.Based on each axis of independent virtual orthogonal coordinate system,the theoretical transformation expression including 9 position error parameters is derived via multiple Euler rotations,and the sensitivity to these position error parameters are investigated with a great deal of curves.The rotation matrix of respective position errors is obtained by Euler rotation.The ideal angle will be picked out by the relative error and the position error will be corrected by a new correction matrix for the optimal angle.The study shows that the measurement error is more sensitive to Ix,Iy,Tyand Tz,less sensitive to Ixand Az,and not sensitive to Tz.After correcting attitude parameters by special angle compensation method via comparison of the relative error,the result of measurement achieves ideal correction effects.