Improvement And Verification For Analog Computation Of Attitude Parameters Of Rotary Steering Drilling Tool

The rotary steering drilling is an advanced automated drilling technology,which is necessary for complicated wells and horizontal extended wells.The accurate attitude parameters are the key to realize the rotary steering drilling technology.In order to get accurate attitude parameters,attitude parameters are measured by inertial devices,for example,the accelerometers,the flux gates or the gyroscopes.The traditional computation of attitude parameters circuit,which uses AD639 arcsine mode,is computed through the basic principle of triaxial accelerometer measure.But in the process of experiment we find that the computing values show obvious saturation distortion and nonlinear distortion while angle reaches large angles(near 90° and 270°),thus the correction method for the analog computing nonlinear is put forward.Through analysis of the analog function generator AD639 internal circuit,the design uses the AD639 internal division part of the circuit.The saturation distortion problem is resolved by correction coefficient circuit,and the precision is improved by piecewise approximation circuit.In the process of test,the designed circuit is tested by discrete method.In order to highlight the correction effect in large angles(90° and 270°),the correction tests use 1° as intervals in the range of large angle,and the correction of data is tested in whole interval(0° to 360°).The experimental results show that the average error of attitude angle can be greatly reduced,and the correction effect is relatively ideal.