On return to the point of entry the two light beams are allowed to exit the ring and undergo interference. A fiber optic gyroscope uses the interference of light to detect mechanical rotation.
How a gyroscope works in a ship. With steadicam : During the filming of the speeder bike chase scene in the movie Return of the Jedi, a steadicam - aka camera stabilizer - rig was used along with two gyroscopes for extra stabilization. In Heading indicators : Gyroscopes are used in heading indicators, also known as directional gyros.
The heading indicator has an axis of rotation that is set horizontally, pointing north. But unlike a magnetic compass, it does not seek north. In an airliner, the heading indicator slowly drifts away from north and needs to be reoriented at regular intervals, using a magnetic compass as a reference.
As gyrocompass : The directional gyro may not seek out north, but a gyrocompass does. It does so by detecting the rotation of the earth about its axis and then seeking the true north, instead of the magnetic north.
Usually, they have built-in damping to prevent overshoot when re-calibrating from sudden movement. With accelerometers : Gyroscopes are also used along with accelerometers, which are used to measure proper acceleration. While a simple accelerometer consists of a weight that can freely move horizontally, a more complicated design comprises a gyroscope with a weight on one of the axes.
For more information about accelerometers, check out our blog on accelerometers. In Consumer Electronics : Given the fact that the gyroscope helps calculate orientation and rotation and is used for maintaining a reference direction or providing stability in navigation, designers have incorporated them into modern technology. In addition to being used in compasses, aircraft, computer pointing devices, gyroscopes are now also used in consumer electronics.
In fact, Apple founder Steve Jobs was the first one to popularize the usage or application of the gyroscope in consumer electronics; he did so by using them in the Apple iPhone.
Since then, gyroscopes have come to be commonly used in smartphones. Moreover, a few features of Android phones - think PhotoSphere or Camera and VR feature - can not work without a gyroscope sensor in the phone. It is the Gyro sensor in our smartphones that senses angular rotational velocity and acceleration. This is what makes it possible for us to play using motion senses in our phones, tablets. When we move our phone, the photo or the video moves due to the presence of a tiny gyroscope in the phone.
In toys : Gyroscopes are also used in toys, in fact there are toy gyroscopes which make for great educational tools as they help kids understand how gyroscopes work. In bicycles : Electric powered flywheel gyroscopes inserted in bicycle wheels are said to be a good alternative to training wheels. In cruise ships : Cruise ships use gyroscopes for leveling motion-sensitive devices such as self-leveling pool tables.
Below is a video about gyroscopes, it tells you how they work, where they are used and more Description of Common Mechanical Gyroscopes A mechanical gyroscope consists of: 1. Optical Gyroscopes Optical gyroscopes operate by sensing the difference in propagation time between counter-propagating beams travelling in opposite directions in closed or open optical paths. Figure 4. Sagnac Effect The underlying operating principle of almost all optical gyroscopes is the Sagnac effect.
Figure 5. Figure 6. Lock-In Effect The lock-in effect occurs only for conditions of weak mutual coupling between the two counter-propagating laser beams. Critical Parameters for RLGs The critical parameters for ring laser gyroscopes are: Size: Larger ring lasers gyroscope can measure lower rotation rates.
Figure 7. Figure 8. Intensity I of the output photo-current of the photo-detector. Figure 9. Key Gyro Performance Factors In this section, five critical parameters for consumer grade gyros will be overviewed: 1. Angle Random Walk In the output of a gyro, there is always a broadband white noise element. Bias Offset Error When input rotation is null, the output of the gyro could be nonzero.
Bias Instability Bias Instability is the instability of the bias offset at any constant temperature and ideal environment. Temperature Sensitivity Gyro performance changes over temperature. Shock and Vibration Sensitivity Noise and Bias offset of gyros also degrade under vibration and shock input. Gyro Technology Comparison The evolution of modern gyros technology, performance and application could be understood through an overview of its history starting from midth century.
Table 1 Gyro technology comparison in terms of Bias Stability. Companies Involved in the Development of Gyroscope Technologies In this section, with reference to the previous gyroscope technologies, we report in Table 2 the companies, divided for geographic area, that actually are the main players in the gyroscope market.
Table 2 Main players for gyroscope market. Conclusions In this review, we reported the currently more diffused gyroscope technologies. Author Contributions All authors have contributed in writing this review paper, discussing the main technology features and performance.
Conflicts of Interest The authors declare no conflict of interest. References 1. Wexford College Press; Kiel, Germany: King A. Inertial Navigation—Forty Years of Evolution. GEC Rev. Inertial Labs. Ezekiel S. Springer-Verlag; Heidelberg, Germany: Fiber-Optic Rotation Sensors. Tutorial Review. Dakin J. Volume 4. Artech House; London, UK: Lefevre H. The Fiber Optic Gyroscope. Aronowitz F. The laser gyro.
In: Ross M. Laser Applications. Volume 1. Macek W. Rotation rate sensing with travelling wave ring lasers. Greiff P. Yazdi N.
Micromachined inertial sensors. Barbour N. Inertial sensor technology trends. IEEE Sens. Halliday D. Fundamentals of Physics. Britting K. Inertial Navigation Systems Analysis. Robertson H. Postulate versus observation in the special theory of relativity. Page L. Juang J. Semiconductor Ring Laser Apparatus. Kiyan R. Bidirectional single-mode Er-doped fiber-ring laser. Cai H. IEEE Trans. Mignot A. Single-frequency external-cavity semiconductor ring-laser gyroscope. Schwartz S.
Solid-state ring laser gyro behaving like its helium-neon counterpart at low rotation rates. Hurst R. Experiments with an m 2 ring laser interferometer. Fan Z. Direct dither control without external feedback for ring laser gyro.
Laser Technol. Korth W. Passive, free-space heterodyne laser gyroscope. Quantum Gravity. High-accuracy absolute rotation rate measurements with a large ring laser gyro: Establishing the scale factor. Vali V. Fiber ring interferometer. Kim H. Air-core photonic-bandgap fiber-optic gyroscope. Lightwave Technol. Quantum Electron. Sanghadasa M. Lloyd S. Wang Z. Dual-polarization interferometric fiber-optic gyroscope with an ultra-simple configuration.
Lei M. Current modulation technique used in resonator micro-optic gyro. Xie H. Integrated Microelectromechanical Gyroscopes. Maenaka K. Analysis of a highly sensitive silicon gyroscope with cantilever beam as vibrating mass.
Actuators A. Clark W. Juneau T. Zhanshe G. Research development of silicon MEMS gyroscopes: a review. Mochida Y. Seshia A. Zaman M. Sharma A. IEEE J. Solid-State Circuits. A mode-matched silicon-yaw tuning-fork gyroscope with subdegree-per-hour Allan deviation bias instability.
Microelectromechanical Syst. Xia D. Trusovs A. Micromachined rate gyroscope architecture with ultra-high quality factor and improved mode ordering. Actuators A Phys.
Wang R. A multiple-beam tuning-fork gyroscope with high quality factors. Tsai C. A MEMS doubly decoupled gyroscope with wide driving frequency range.
Pyatishev E. Petersburg, Russia. Silicon Sensing Selection Guide. Analog Devices, Inc. Products Table. Emcore Fog Products Table. Kvh Fog Products Table. Aviation Gyro Photoelectricity Technology. MT Microsystems Co. Navtech Inc. Panasonic Coorporation. Seiko Epson Corporation.
Silicon Sensing Systems Ltd. Civitanavi Systems s. InnaLabs Ltd. Omni Instruments. Robert Bosch GmbH. Sensonor AS. STMicroelectronics N. Emcore Corporation. Freescale Semiconductor, Inc. Hewlett-Packard Development Company, L. Honeywell International Inc. InvenSense, Inc. Kearfott Corporation. Kionix Inc. KVH Industries, Inc. LORD Corporation. Measurment Specialties Inc. Qualtre Inc. Rockwell Collins Inc. Systron Donner Inertial.
TE Connectivity Ltd. Teledyne Technologies, Inc. UTC Aerospace Systems. Watson Industries Inc. Inertial Technologies JSC. OAO Polyus. Optolink Scientific Ltd. A gyroscope with an electrically powered motor and metal gimbals has four basic sets of components. These are the motor, the electrical components, electronic circuit cards for programmed operation, and the axle and gimbal rings.
Most manufacturers purchase motors and electrical and electronic components from subcontractors. These may be stock items, or they may be manufactured to a set of specifications provided to the supplier by the gyroscope maker. Typically, gyroscope manufacturers machine their own gimbals and axles. Aluminum is a preferred metal because of its expansion and strength characteristics, but more sophisticated gyroscopes are made of titanium.
Metal is purchased in bulk as bar stock and machined. Using the electrical and mechanical aspects of gyroscopic theory as their guides, engineers choose a wheel design for the gimbals and select metal stock appropriate for the design. The designs for many uses of gyroscopes are fairly standard; that is, redesign or design of a new line is a matter of adapting an existing design to a new use rather than creating a new product from the most basic beginning.
Design does, however, involve observing the most fundamental engineering practices. Tolerances, clearances, and electronic applications are very precise.
For example, design of the gimbal wheels and design of the machining for them has a very small tolerance for error; the cross section of a gimbal must be uniform throughout or the gyroscope will be out of balance. The gyroscope is an elegant example of an application of simple principles of physics. Because it is simple, manufacturers closely guard any proprietary techniques.
Because the gyroscope is a simple device with wideranging uses, some require more manufacturing processes. The manufacturing steps described above take about 10 hours and result in a free gyroscope for an application such as missile guidance. A more exotic gyroscope may require 40 hours of assembly time.
Quality control is essential throughout the design and assembly processes in manufacturing gyroscopes because the instruments are part of manned aircraft, unmanned missiles, and other transportation and weapons devices that could cause catastrophes if they fail.
Engineers, scientists, and designers are highly educated and trained before they are hired and while on the job. Assembly-line workers must pass initial training to be hired, and they have regularly scheduled, ongoing training sessions. Many of the quality standards that must be met in gyroscope manufacture can be measured, so in-process inspection is performed throughout manufacture.
Quality control at the highest level is performed by inspectors from outside the company and includes government inspectors.
Customers also perform their own inspections and acceptance testing; if the manufacturer's product fails the customers' tests, the failed gyroscopes are returned. Gyroscope manufacturers do not produce byproducts, but they tend to make full lines of gyroscopes for a wide variety of applications.
They also do not produce much waste. Machining the gimbals and rings produces some aluminum chips, but these are collected and returned to the aluminum supplier for recycling. Manufacturers observe the mandates of the Occupational Safety and Health Administration OSHA for light, ventilation, and ergonomics comfortable seating and work benches that reduce the likelihood of repetitive stress injuries.
Humidity must be maintained in the plant to prevent electrostatic discharge. Minor quantities of cleaning solvents are required, but citrus-based cleaners that are benign harmless are used. Uses for gyroscopes are increasing with the number of devices that require guidance and control. Although the basics of the gyroscope are grounded in the laws of physics and can never change, the technology is evolving.
Mechanical and electrical methods for providing the spinning mass that makes the gyroscope work are gradually being replaced by ring lasers and microtechnology. Coils of thin optical fibers hold the key to compact, lightweight gyroscopes that might have applications in navigation systems for automobiles. The gyroscope is such a simple but sophisticated instrument for keeping so many tools in transportation, exploration, and industry in balance that, seen or unseen, it certainly has a place in the future.
Campbell, R.
0コメント