The accurate stable measurement of position for a shearer is a key technology in realizing an automated fully mechanized coal mining face. Using as a base of SINS/UWB integrated positioning system, the signal interference and node damage of UWB often cause an invalid integrated positioning system, because of the bad working environment of the shearer in the coal mine. Consequently, the positioning accuracy of the SINS/UWB integrated system decreases quickly, due to the drift error of SINS. Aiming at two invalid styles include partial anchor node failure and all anchor nodes failure of UWB, this paper proposes a stable SINS/UWB integrated positioning system of a shearer using the multi-model intelligent switching method based on a tightly coupled integrated model and a decision tree fault-tolerant model. First of all, the tightly coupled integrated model and the decision tree fault-tolerant model are built using measured distance and the final position of UWB, respectively. Second, the multi-model intelligent switching algorithm can be established based on the shearer Markoff movement state and residual threshold judgment of a Kalman Filter. Finally, the experimental results show that the multi-model intelligent switching faulttolerant positioning algorithm can effectively overcome increased positioning error of the tightly coupled model and the decision tree model based on these two invalid styles. The maximum position error with the positioning model proposed in this paper is 0.93 m in 327 s, and the positioning accuracy with a multi-model intelligent switching model is much greater than that with tightly coupled integration and the decision tree fault tolerant models. INDEX TERMS Fault-tolerant integrated positioning system, multi-model intelligent switching algorithm, shearer, SINS/UWB, tightly-coupled, decision tree.

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This work presents the machining parameters optimization on machining metal matrix composites using genetic algorithm in the Taguchi method with the objectives of minimization of surface roughness, cutting force, maximization of metal removal rate, cutting power, specific cutting energy, cutting power and machining time. Experiments were conducted on aluminium silicon carbide Metal Matrix composite using TiN coated HSS twist drills. Optimal setting of parameters have been identified using Taguchi Technique and Genetic algorithm. Genetic algorithm is developed in ‘C’ language. The presented work gives a better results and it can be used for any machining parameter optimization in solving multiple response problems.

Accurate measurement of drill bit position and direction is the main technology to realize automation and intelligence in oil drilling field. In recent years, with the rapid development of complex drilling technologies such as high deviation wells, directional wells and horizontal wells, higher requirements have been put forward for measurement technology, especially for real-time monitoring of bit attitude and position during the drilling process. Therefore, for the past few years, the measurement while drilling (MWD) system has been widely recognized and developed rapidly in precision targeted drilling. among them, strapdown inertial navigation system (SINS) consisting of accelerometer and gyroscope is the key of down-hole measurement while drilling. To solve the problem of accumulated errors in SINS, in this paper, a positioning error correction method based on kinematic constraint-aided (KC) SINS zero velocity updated (ZUPT) model is proposed. Firstly, based on the acceleration and angular velocity information measured by SINS, empirical mode decomposition (EMD) and wavelet de-noising reconstruction are performed for MWD signals. Secondly, the static detection model of the drill bit is established by using the reconstructed signal. Thirdly, using drilling technology to analyze the motion attitude of the bit, the KC model of the down-hole bit is established. By analysis the alternating effect of the KC model and the ZUPT model in the process of the bit movement and stop, the ZUPT model of the SINS is established. Finally, experimental verification is performed by building a drilling platform. The experimental results show that the maximum positioning error of the proposed positioning model is 0.15 m within 300 s. Comparing with a single KC model and a single ZUPT model, the bit positioning accuracy is improved to 92.6%, which effectively suppresses the original cumulative error, and verifies the feasibility of the proposed method. INDEX TERMS Measurement while drilling system, strap-down inertial navigation system, empirical mode decomposition, kinematic constraint-aided, zero velocity updated.

In the oil industry, directional drilling technology plays a significant role in oil-gas exploration.The key to success of directional drilling technology is locate the borehole accurately using measurement while drilling instruments. Measurement While Drilling(MWD) technology has the problems of data loss and gross error in complex down hole environment. Aiming at the problems that gross error and data missed consequences the accuracy of positioning calculation seriously, this paper presents a method of fault-tolerant integrated borehole trajectory location based on geomagnetism/IMU of MWD system. Firstly, the geomagnetic survey system is established to locate the borehole position based on tri-axis fluxgate and tri-axis accelerometer. The Inertial Measurement Unit(IMU) calculates the borehole trajectory at the same time. Then, the fault-tolerant judgment mechanism is introduced to discriminate and evaluate data loss and gross error of measurement parameters. Furthermore, Kalman Filter algorithm is implied to construct faulttolerant integrated borehole trajectory positioning system. Finally, the simulation experiment is performed on the drilling experimental platform. The experimental result shows that the fault-tolerant integrated borehole trajectory positioning system can detect data loss and gross error effectively. In addition, the location precision of the fault-tolerant integrated positioning system can be maintained within 1 meter when the time of data missed and gross error state lasts for 6min respectively. From the simulation experiments, comparing with the position calculation of pure geomagnetism, and the method of integrated MEMS and geomagnetism, the precision of the fault-tolerant integrated location calculation is improved by 68.7% and 62.8% respectively.INDEX TERMS Measurement while drilling, borehole trajectory, geomagnetic survey, inertial measurement unit, fault-tolerant integrated positioning.