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Example 16: Unity and Mobile Sensors Bond
Published in Ata Jahangir Moshayedi, Amin Kolahdooz, Liefa Liao, Unity in Embedded System Design and Robotics, 2023
Ata Jahangir Moshayedi, Amin Kolahdooz, Liefa Liao
Nowadays, making the game and running them on the mobile platform is more in demand. But, on the other hand, mobile is counted as an embedded system that can help acquire various data and even analyse these days. This chapter will learn how to interact with your mobile equipped with accelerometer and gyroscope, or gyro as short form, sensors. A gyroscope is a device that uses Earth's gravity to determine orientation. An accelerometer is a compact device designed to measure non-gravitational acceleration. For example, accelerometer sensors in mobile phones use to sense the phone's orientation. The gyroscope adds an extra dimension to the info supplied by the accelerometer by tracking rotation or twist. An accelerometer measures the linear acceleration of movement, while a gyro measures the angular rotational velocity. Both sensors measure the rate of change; they measure the rate of change for different things. In brief, an accelerometer will measure the directional movement. The gyroscope is a very sophisticated tiny mechanism that has found many diverse applications with accurate orientation measurements.
Command and Control
Published in Douglas M. Marshall, R. Kurt Barnhart, Eric Shappee, Michael Most, Introduction to Unmanned Aircraft Systems, 2016
To determine the basic movement and attitude of the aircraft, the autopilot makes use of accelerometers and gyros. These are usually found on board the autopilot itself. Accelerometers detect acceleration along an axis, where gyros detect angular velocity about an axis (Woodman 2007). These sensors require calibration or initialization. It is important to note that because accelerometers by definition measure acceleration, they will indicate the acceleration due to gravity. Accelerometers and gyros found on most autopilots are not used alone for primary long-term navigation. The reason for this is that the small accelerometers and gyros suitable for these systems do not have enough precision to be useful over time; errors are additive without some correction. These sensors are relatively low-cost microelectric mechanical systems (MEMS) devices fabricated using the same methods and materials as those employed by the integrated circuit industry (Cork 2014). Many times on the outside, a MEMS device looks exactly the same as any other solidstate chip mounted on a circuit board, and is just as small—even with all the elements for three accelerometers and three gyroscopes (sometimes even three magnetometers as well) in the same package. It is important to remember that MEMS are mechanical devices, and subject to damage and failure. Though damage is extremely rare, care should be taken to avoid sharp drops and falls. They should be checked regularly for proper operation.
Attitude Sensors
Published in Chingiz Hajiyev, Halil Ersin Soken, Fault Tolerant Attitude Estimation for Small Satellites, 2020
Chingiz Hajiyev, Halil Ersin Soken
Although they may differ structurally, all MEMS gyros function based on the principle of measuring the Coriolis force due to the rotation. A MEMS gyro can be dynamically modeled using a spring-damper-mass system (Figure 3.21) to describe the measurement principle. In order to obtain the dynamics of the gyroscope attached to a rotating object, this analysis should be applied to the position vector of a vibratory gyroscope proof mass. Assuming that the gyro is measuring the angular rate about z axis, ωz, and its driving and sensing axes are x and y axes respectively, the simplified 2° of freedom equations of motion of a MEMS gyro can be written as mx¨+cxx.+kxx=Fd+2mωzy.,my¨+cyy.+kyy=−2mωzx..
Self-calibration and compensation of residual gyro drifts for rotation inertial navigation system with fibre optic gyro
Published in Journal of Modern Optics, 2019
Jie Sui, Lei Wang, Wei Wang, Tianxiao Song
The fibre optical gyro (FOG) is suitable for the rotation inertial navigation system (RINS) due to its light weight, small volume, large measure range and high reliability (5-7). The RINS based on FOGs is researched increasingly to further improve its navigation performance in recent years. The rotation schemes (8,9), alignment algorithms (10,11) and self-calibration methods (12,13) of the FOG RINS are studied to demonstrate that the FOG RINS has huge prospects for navigation performance improvement. However, the temperature (14-16) and magnetic field (17,18) of the environment are great influencing factors of the drift of the FOG, and can reduce the positioning accuracy of the INS. In the RINS, FOGs are rotating continuously. The main sources of the magnetic field and heat, namely the circuits and motors, are fixed to the case of the RINS. Thus the FOGs-sensitive temperature and magnetic field changes with FOGs pointing to different directions. Those factors lead to different gyro drifts at different directions during the rotation period. Thus the average value of the drifts in the body frame would be non-zero, meaning the existence of the so called residual drifts, which can weaken the modulating performance of the rotation technique. Residual drifts can lead to significant navigation errors, and thus deserve in-depth analysis.
Design of a speech-enabled 3D marine compass simulation system
Published in Ships and Offshore Structures, 2018
Bin Fu, Hongxiang Ren, Jingjing Liu, Xiaoxi Zhang
The gyrocompass system mainly includes the master compass, electronic transmission box, azimuth repeater compass, liquid connector, damping weight, fork-follower ring, gyro ball, azimuth servo motor, and compass room scene, along with some other parts (Guan and Liu 2009). The master compass is used to provide the heading information, the electronic transmission box is used to launch and adjust the parameter settings. The azimuth repeater compass is mainly used to determine the target position and the liquid connector is used to generate horizontal compass axis control torque. The damping weight serves to generate the compass's vertical shaft friction torque, the fork-follower ring supports the sensitive parts and the gyro ball is mainly used to find the north azimuth servo motor to drive the range dial and rotate the fork-follower ring. The compass room scene is used to place the system equipment and support scene roaming.
About One Way to Increase the Accuracy of Navigation System for Ground Wheeled Robot Used in Aircraft Parking
Published in Smart Science, 2020
Alexander I. Chernomorsky, Konstantin S. Lelkov, Eduard D. Kuris
The measurement frequency of the directional gyroscope is 100 Hz. The measurements of the angular velocity of GWR motion contain a systematic zero-shift error (the accepted value of the gyroscope zero shift is 5 degrees per hour) and a noise component described by a random process with a Gaussian distribution of a random variable [29]. The mean value of is zero, and the standard deviation (SD) [30] is 0.05 rad/s. The graph of measurements of the angular velocity of the GWR with a directional gyro is presented in Figure 6.