Research And Improvement Of Strapdown Inertial Navigation Algorithm In Inclinometer

Drilling inclinometer is an instrument that utilizes inertial measurement unit such as gyroscopes and fluxgates to measure the angle and depth of the borehole.It is widely used in oil exploration and geological exploration.The calculation accuracy of the position and attitude algorithm directly determines the accuracy of the azimuth,inclination,tool face angle and trajectory which measured by the drilling inclinometer.Therefore,the strapdown inertial navigation algorithm is applied to the drilling inclinometer as a position and attitude algorithm to solve the problem of demanding work environment and low measurement efficiency that exist in the traditional drilling inclinometer.In this paper,the main content of this paper is to study the strapdown inertial navigation algorithm as a position and attitude algorithm,and simulate the algorithm.Firstly,this paper studies the traditional strapdown inertial navigation algorithm.The attitude calculation,velocity calculation and position calculation algorithm in the traditional strapdown inertial navigation algorithm are described in detail.The different attitude calculation algorithms are analyzed and compared.The self-aligning method of drilling inclinometer is designed to find the attitude and position information of the initial time of drilling inclinometer to start the iterative process of the navigation algorithm.The experimental results of the traditional strapdown inertial navigation algorithm is carried out that the drilling inclinometer based on the traditional navigation algorithm can work normally.However,with the increase of simulation time,there will be divergence problem of attitude caused by the cumulative error and the fast change of attitude.And the attitude divergence problem will affect the accuracy of the speed and position,resulting in drilling inclinometer can't complete the measurement work.Secondly,this paper proposes a strapdown inertial navigation algorithm based on the dual quaternion as the position and attitude algorithm of drilling inclinometer.The dual quaternion strapdown inertial navigation algorithm has adopted a new expression in the description of rigid body motion and calculation of position information,to improve the measurement accuracy of the drilling inclinometer in principle.In the process of studying spiral vector algorithm in the dual quaternion strapdown inertial navigation algorithm,a spiral vector optimization algorithm is proposed to solve the divergence problem of attitude in the traditional algorithm,and to improve the attitude and position accuracy of drilling inclinometer.According to the dual quaternion characteristics,the calculation flow of dual quaternion strapdown inertial navigation algorithm is arranged,to complete the extraction work of position and attitude information of drilling inclinometer.Finally,in this paper,the spiral vector optimization algorithm based on dual quaternion is analyzed and experimented.The relationship between the spiral vector optimization algorithm and the traditional optimization algorithm in the spiral motion environment is clarified.And we compared the dual quaternion strapdown inertial navigation algorithm with the traditional algorithm in terms of attitude error and velocity error.We designed the simulation experiment to compare calculation accuracy of two algorithms.The angular velocity and acceleration information obtained by the micro inertial sensor MPU6050 are processed by MATLAB software.The experimental results show that the optimization algorithm based on dual quaternion is better than the traditional strapdown inertial navigation algorithm in the calculation of attitude angle and position.So it can be applied and popularized in drilling inclinometer to achieve the purpose of improving the measurement accuracy.