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Command and Control
Published in R. Kurt Barnhart, Douglas M. Marshall, Eric J. Shappee, Introduction to Unmanned Aircraft Systems, 2021
Large UAS sometimes have dedicated inertial management units, or INS, that are designed to operate without the need for external sources of real-time information. These systems estimate their current position from a known heading and starting point. From this starting point, inertial systems rely on detecting the acceleration (and therefore speed) of the aircraft in each axis, and the rotational rate about each axis (and therefore heading) to perform dead reckoning. For some inertial systems, these three accelerometers and three gyros are all that is required; however, many times a magnetometer is added to detect the magnetic compass heading and help reduce the rotational error of the gyro system. In some cases, GPS is also added to correct errors that accumulate (Cork 2014). The fusion of data from these sensors is processed with a computing device to determine relevant navigation information such as current position, velocity, and heading. Stereo-optical sensor data (optical odometry) may be incorporated with the INS data as well by using an extended Kalman filter. This provides accuracy close to that of GPS (Kelly et al.)
Command and Control
Published in Douglas M. Marshall, R. Kurt Barnhart, Eric Shappee, Michael Most, Introduction to Unmanned Aircraft Systems, 2016
A small UAS inertial measurement unit (IMU) incorporates (usually MEMS) gyros and accelerometers to sense and input rate of change and rotation data to the inertial navigation system (INS), which, in turn, uses this data to compute velocity, attitude, and position of the aircraft without the need for external sources of real-time information. These systems estimate their current position from a known heading and starting point. From this starting point, inertial systems detect acceleration (and therefore speed) of the aircraft in each axis and rate of rotation about each axis (and therefore heading) to perform dead reckoning. For some inertial systems, these three accelerometers and three gyros are all that is required; however, many times a magnetometer is added to detect the magnetic compass heading and help reduce the rotational error of the gyro system. In some cases, GPS is also added to correct errors that accumulate (Cork 2014). The fusion of data from these sensors is processed with a computing device to determine relevant navigation information such as current position, velocity, and heading. Stereo-optical sensor data (optical odometry) may be incorporated with the INS data as well through the use of an extended Kalman filter. This provides accuracy close to that of GPS (Kelly et al. 2007).
Technologies
Published in Henry H. Perritt, Eliot O. Sprague, Domesticating Drones, 2016
Henry H. Perritt, Eliot O. Sprague
A fluxgate magnetometer, also known as a fluxgate compass, detects the orientation of the Earth’s magnetic field by measuring the difference between the currents on two coils of wire wrapped around a magnetizable core. One coil is energized by an AC signal, which alternately magnetizes and demagnetizes the core and induces a current in the second coil. When the Earth’s magnetic field impinges on the core it changes its level of magnetism and alters the current in the second coil. The orientation of the device causes the effect of the Earth’s magnetic field to be stronger or weaker, thus enabling associated logic to determine the magnetic heading of the device with respect to the Earth’s magnetic field. Miniaturized magnetometers are regularly used to drive a magnetic heading indicator on aircraft. Their size and weight suit them well for microdrones with limited payload capacity. A small compass magnetometer sensor module could be bought on Amazon in October 2015, for less than $10.
On the application of drones: a progress report in mining operations
Published in International Journal of Mining, Reclamation and Environment, 2021
Khadija Omar Said, Moshood Onifade, Joseph Muchiri Githiria, Jibril Abdulsalam, Michael Oluwatosin Bodunrin, Bekir Genc, Oluwagbenga Johnson, Jide Muili Akande
For drones to perform different functions, lightweight intelligent sensors are embedded in drones to enable proper operation of drones. During flight, the rotation and degree of tilt is crucial to ensure the drone is flown to the desired location and this is achieved using the inertia units installed in them. These include magnetometer for indicating the orientation of the magnetic field to ascertain heading, accelerometer to calculate linear motion in all directions and gyroscope to determine tilting and rotational rate. For precision and accuracy of manoeuverability of drones, GPSs are used to know the exact location of drones above ground, therefore allowing users to know the exact coordinates of data points. More sensors are installed for measurement, monitoring, and collection of data as described below.
Demanded versus assumed friction along horizontal curves: An on-the-road experimental investigation
Published in Journal of Transportation Safety & Security, 2018
R. Vaiana, T. Iuele, V. Gallelli, D. Rogano
As stated before, speed values for each driver were collected (with a frequency of 1 Hz) by using a GPS tracker software installed on all mobile devices used by selected drivers. From speed data, instant lateral acceleration values were derived as follows: where is the current speed value recorded each second (m/s), is the turn instant radius (m), which can be evaluated using the relationship proposed by Abdulrahim (2006) and Jochem, Pomerleau, Kumar, and Amstrong (1995) (Equation 6).where is the current speed value (m/s) and is variation of the heading in the temporal unit. The heading represents the current direction compared to the North direction, expressed as degree with positive rotation with respect to the East. Moreover, the values of this variable are directly provided by the GPS.
Design and simulation of sensor fusion using symbolic engines
Published in Mathematical and Computer Modelling of Dynamical Systems, 2019
Heading is measured using magnetic field sensors. A well-calibrated magnetometer [3,4] pointing to magnetic north will ideally measure reference magnetic field . Similar to gravity, can be calculated from standard tables as the one publicly available on Natural Resources Canada, magnetic field calculator [18]. If the magnetometer has a non-zero heading, will be projected to body axis accordingly. To calculate heading from magnetometer measurements, the following simple formula can be used [1,4]: