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Average Angle Method with Microsoft Excel for Directional Well Path Planning and Risk Monitoring
Published in Subrata Borgohain Gogoi, Advances in Petroleum Technology, 2020
Basically, there are two types of survey instruments: Magnetic sensors can be run within the subsurface environment having less magnetic interference in order to obtain correct readings of a downhole survey [394]. There are two categories of magnetic sensors, mechanical compass and electronic compass.A mechanical compass uses a compass card, and a pendulum float device arrangement is employed in order to measure the inclination changes with respect to the magnetic north. In an electronic compass the bit position is measured by gravity accelerometers and fluxgate magnetometers [395].Gyroscopic sensors measure errors due to magnetic disturbances occurring due to the presence of magnetic elements downhole. Incorrect readings can be overcome by the use of gyroscopes. The principal element of the gyro is a rapidly spinning weighted wheel which maintains a present direction by resisting changes in direction, owing to its inertia [393].
Trajectory Planning in Autonomous Vehicles using GPS and Digital Compass
Published in P. C. Thomas, Vishal John Mathai, Geevarghese Titus, Emerging Technologies for Sustainability, 2020
This system best works when there is 5-6 satellite connection, as the accuracy of the position is increased to a great extent, preferably operated outdoors with clear sky. The GPS receiver tends to have a lag in data stream; usually data comes at 1Hz, better to have a faster stream of data (> 5Hz). If a single core/thread controller is used the vehicle will turn out to have a slower response or reaction time. The magnetic field of the Earth is not a constant; it changes from time to time and also from place to place. The phenomenon is known as magnetic declination or magnetic variation. This results in an angle between the magnetic north (direction of the north pole of a magnetized compass needle, corresponding to the direction of the Earth’s magnetic field lines) and the true north (direction along meridian towards the geographic North Pole). This angle varies depending on the position on the earth’s surface and changes over time.
Electricity
Published in Kevin Robinson, Practical Audio Electronics, 2020
Electric and magnetic fields can to a large extent be viewed as just two aspects of the greater single electromagnetic field. The idea of a permanent magnet should be familiar, with a field surrounding it which can have an effect on certain metals and other magnets close by, without any physical contact. One magnet can be made to push another across a tabletop without the two ever touching. A compass can be relied upon to find north because the compass needle is a magnet and its field interacts with the earth’s magnetic field to line up showing north–south. But remember also that a compass can easily be fooled by stronger magnetic fields produced by electrical devices and other magnets in the vicinity. The freely rotating compass needle lines up with the strongest magnetic field it finds. In fact a compass is occasionally used in this fashion when working with electric guitar pickups as it provides an easy method of determining the orientation of the magnets in the pickup, which can be useful information when wiring multiple pickups into a guitar (see Learning by Doing 20.4).
Calculation of the deviation coefficients for marine magnetic compass
Published in Journal of International Maritime Safety, Environmental Affairs, and Shipping, 2019
The compass needle is oriented to north direction by a magnetic force produced by the magnetic field of earth. However, when using this equipment, it finds that the magnetic of earth also acts on the metal materials on ship and magnetize them to cause another magnetic field which is called as the magnetic field of ship. This magnetic field also affects to the needle of magnetic compass. Therefore, the orientation of magnetic compass is influenced simultaneously by both earth and on-board iron magnetic fields. The total of these forces makes the magnetic compass to have low accuracy and significant error in course.
Filtering based multi-sensor data fusion algorithm for a reliable unmanned surface vehicle navigation
Published in Journal of Marine Engineering & Technology, 2023
Wenwen Liu, Yuanchang Liu, Richard Bucknall
A GNC system obtains the absolute observations (measurements) of the USV’s position and heading from a GPS sensor and an electronic magnetic compass. The absolute measurements are associated with random noises, which are described as Rooted Mean Square (RMS) errors in the sensor manuals. RMS error indicates that at 68% probability that the measurement lies within the range of the error from the true position and twice the range at 95% probability. Therefore, the sensor models of GPS can be defined with an additive noise component as: The major magnetic measurement error results from the distortion of the Earth’s magnetic field by nearby ferrous effects, sensor noise and magnetic interference. In practical applications, compasses are mounted in vehicles and platforms that usually have ferrous materials nearby. These nearby ferrous materials will generate permanent magnetic fields (hard irons) or varying magnetic fields (soft irons) to distort the Earth’s magnetic field. Soft irons affect the magnetometer output by varying amounts depending on the compass orientation. This varying bias effect will distort the shape of the 2D magnetic field locus from a circle into an ellipse. Hard and soft iron distortions are the major error sources for magnetic compasses and compensating for these effects is essential to their application (Langley 2003). Normally, a calibration process is conducted to remove the bias after installation since the bias is constant without change of installation environment. In a similar manner to the GPS module, the electronic compass also provides absolute measurements of vehicle’s headings with an additive random noise that can be expressed as Equation (9). where and are the true position and heading respectively; and are the noisy measurements; and and are the uncertainty with a normal distribution with the standard deviation of their RMS error value and .