How does gyroscope work

It used an electrostatic comb drive to move the proof-masses in x -axis and a capacitive detecting in y -axis to sense rotation in z -axis. Drive and sense mode were electrostatically balanced to achieve perfect mode matching; this design improved sensitivity, bias stability and noise floor. Sharma, through further research on the M2-TFG, designed the closed-loop circuit based on a transimpedance amplifier with a dynamic range of dB, capable to keep the matched-mode.

Experimental data showed a capacitive resolution of 0. Zaman in reported an improvement of the M2-TFG using two high-quality factor resonant modes.

From to , Trusov et al. These structures forced an anti-phase drive-mode and a linearly-coupled dynamically-balanced anti-phase sense-mode, that prioritizes sense-mode quality factor. The prototypes were characterized in a vacuum chamber, demonstrating a quality factor drive-mode of 67, and of , for the sense-mode [ 54 , 55 ].

In fact, Wang et al. Further measurements pointed out a rate resolution of 0. Other researches were performed towards enabling a wider bandwidth to expand flexibility and ease of use. Thus, in , Tsai et al. Finally, the report by Pyatishev et al. In this section, five critical parameters for consumer grade gyros will be overviewed:. In the output of a gyro, there is always a broadband white noise element. Angle Random Walk describes the error resulting from this noise element and can be evaluated using the Allan Variance technique.

Active elements of the gyro are the major contributors to random noise laser diode and photo diode for optical gyroscopes and the vibrating beam and detection electronics for MEMS. Noise is one of the most important differences between optical and MEMS gyro performance, resulting in different precision and accuracy in measurements. When input rotation is null, the output of the gyro could be nonzero. The equivalent input rotation detected is the Bias Offset Error. Fixed errors, such as Bias Offset Error, can be easily corrected.

Bias Instability is the instability of the bias offset at any constant temperature and ideal environment. It can be measured using the Allan Variance technique. Bias instability introduces errors that may not be easy to calibrate. Its influence is greater on longer measurement periods, so Bias Instability is one of the most critical factors in the gyro selection process for applications that requires excellent accuracy over long time.

Gyro performance changes over temperature. A characterization of parameters such as noise, bias offset and scale factor over temperature is necessary to verify that gyro performance meets system targets. Noise and Bias offset of gyros also degrade under vibration and shock input. Vibration performance is critical in many military and industrial applications, because of the presence of numerous factors such as engines or gunfire.

The evolution of modern gyros technology, performance and application could be understood through an overview of its history starting from midth century. Originally, it was a full mechanical system that found its major use in navy and aviation applications, especially during WWI as a pilot system for ship steering and for self-guided missiles. The first improvement step consisted in developing several DTG versions equipped with electronics.

These kinds of systems are still used, even if their commercialization stopped some years after. Being very accurate but complex at the same time, large and expensive to manufacture, their main application consisted in replacing mechanical gyros components and systems in a wide variety of guidance, navigation and aeronautics applications, including man-portable and tripod target locator systems.

In the last twenty years, a different technology, based on solid state integrated devices, appeared. MEMS have achieved important improvements since first solutions to date. They have met the market request, in particular in consumer and industrial fields, allowing high robustness and sufficiently high performance for the corresponding grade.

In consumer market, a large number of devices are provided with an embedded MEMS gyroscope. Segway-like Human Transporter, drones, smartphones and IOT devices are examples of markets and applications. In industrial applications, the majority of systems where feedback control is needed, are equipped with a MEMS gyro, e.

FOG-grade MEMS gyros are currently in an advanced stage of development, paving the way to the replacement of optical gyros in the next future. Actually, we can classify gyro technology considering the bias stability as fundamental performance parameter as shown in Table 1.

Fiber Optic Gyroscopes could be considered the low-cost version of Ring Laser Gyroscopes, being a mature technology with similar performance and sizes. Thus, development in fiber technology can lead to the design of high-performance FOGs. At the same time, a similar process will involve FOGs and MEMS gyro technologies, because they show a few significant advantages, such as reduction of size, power and cost, and it seems to be almost mature to move on the next performance grade.

In [ 59 , 60 ], two comparison tables on commercial MEMS gyros by two different manufacturers are shown. They focus on the most important performance parameters of their available products.

The crucial point that influences the price of the product is the bias instability, which is one of the most important elements identifying the performance grade each gyro receives. All of the shown parameters especially the dynamic range are useful to choose the best gyro for the specific application.

In [ 61 , 62 ], comparative tables on commercial FOGs are shown. 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. As discussed before, this market trend is related to the low cost of MEMS gyroscopes, allowing them to be employed for low-cost consumer electronics applications. North America is the geographic area where the gyroscope technologies are more developed and it is followed by Europe and Asia.

In this review, we reported the currently more diffused gyroscope technologies. All authors have contributed in writing this review paper, discussing the main technology features and performance. National Center for Biotechnology Information , U. Journal List Sensors Basel v. Sensors Basel.

Published online Oct 7. Vittorio M. Find articles by Vittorio M. Find articles by Antonello Cuccovillo. Find articles by Lorenzo Vaiani. Find articles by Martino De Carlo. Find articles by Carlo Edoardo Campanella. Author information Article notes Copyright and License information Disclaimer.

Received Aug 21; Accepted Sep This article has been cited by other articles in PMC. Abstract This paper is an overview of current gyroscopes and their roles based on their applications. Keywords: mechanical gyroscopes, optical gyroscopes, MEMS gyroscopes. Open in a separate window. Figure 1. Mechanical Gyroscopes A mechanical gyroscope essentially consists of a spinning mass that rotates around its axis.

Principle of Mechanical Gyroscopes: Gyroscopic Effects The basic effect upon which a gyroscope relies is that an isolated spinning mass tends to keep its angular position with respect to an inertial reference frame, and, when a constant external torque respectively, a constant angular speed is applied to the mass, its rotation axis undergoes a precession motion at a constant angular speed respectively, with a constant output torque , in a direction that is normal to the direction of the applied torque respectively, to the constant angular speed [ 14 ].

Figure 2. Mechanical Displacement Gyroscopes The primary application of gyroscopic effects consists in the measurement of the angular position of a moving vehicle. Mechanical Rate Gyroscopes Rate gyros measure the angular speed of a vehicle during rotary motion.

Figure 3. 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: A typical airplane uses about a dozen gyroscopes in everything from its compass to its autopilot. The Russian Mir space station used 11 gyroscopes to keep its orientation to the sun , and the Hubble Space Telescope has a batch of navigational gyros as well. Gyroscopic effects are also central to things like yo-yos and Frisbees! In this edition of HowStuffWorks , we will look at gyroscopes to understand why they are so useful in so many different places.

You will also come to see the reason behind their very odd behavior! If you have ever played with toy gyroscopes, you know that they can perform all sorts of interesting tricks.

They can balance on string or a finger; they can resist motion about the spin axis in very odd ways; but the most interesting effect is called precession.

This is the gravity-defying part of a gyroscope. The following video shows you the effects of precession using a bicycle wheel as a gyro:. The most amazing section of the video, and also the thing that is unbelievable about gyroscopes, is the part where the gyroscopic bicycle wheel is able to hang in the air like this:.

This mysterious effect is precession. In the general case, precession works like this: If you have a spinning gyroscope and you try to rotate its spin axis, the gyroscope will instead try to rotate about an axis at right angles to your force axis, like this:. Why should a gyroscope display this behavior? It seems totally nonsensical that the bicycle wheel's axle can hang in the air like that.

If you think about what is actually happening to the different sections of the gyroscope as it rotates, however, you can see that this behavior is completely normal!

Let's look at two small sections of the gyroscope as it is rotating -- the top and the bottom, like this:. 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.

To get a better understanding of this, we will first need to have a look at their "strange behavior. Gyroscopes, in their most basic form, are a spinning wheel or disk on an axle. More complex examples will also be mounted on a metal frame or a set of moveable or immovable frames or gimbals for increased precision of the apparatus. Although they seem like simple objects on the surface, they can perform some very strange tricks.

When the wheel isn't spinning, gyroscopes are effectively over-engineered paperweights. If you try to stand one up, it will simply fall over obviously. The key to them is in their spin. Perhaps you've played with gyroscopes as a child? Maybe you have a fidget spinner? If so, you'll remember how they can perform lots of interesting tricks.

You can balance one on a string or your finger whilst it is in motion, for example. Another noticeable property of them, if you've ever held one, is that it will try to resist attempts to move its position. You can even tilt it at an angle when suspended from a stand, and it will appear to levitate, albeit whilst orbiting the stand.

Even more impressively, you can lift up a gyroscope with a piece of string around one end. The explanation for this phenomenon is tricky to understand intuitively. Their ability to seemingly defy gravity is a product of angular momentum , influenced by torque on a disc, like gravity, to produce a gyroscopic precession of the spinning disc or wheel.

This phenomenon is also known as gyroscopic motion or gyroscopic force, and it has proved to be very useful indeed for us humans. These terms refer to the tendency of a rotating object, not just a gyroscope, to maintain the orientation of its rotation.

As such, the rotating object possesses angular momentum, as previously mentioned, and this must be conserved. Because of this, t he spinning object will tend to resist any change in its axis of rotation, as a change in orientation will result in a change in angular momentum.

Another great example of precession occurs with the planet Earth too. As you know, the Earth's rotational axis actually lies at an angle from the vertical which, owing to its angle, traces a circle as the rotational axis itself rotates. While not entirely relevant to this article, the reason for Earth's odd tilt is actually pretty interesting.

This effect is enhanced the faster the disc or wheel is spinning, as Newton's Second Law predicts. This seems pretty obvious to anyone with a basic knowledge of physics. The main reason they seem to defy gravity is the effective torque applied to the spinning disc has on its angular momentum vector. The influence of gravity on the plane of the spinning disc causes the rotational axis to "deflect".

This results in the entire rotational axis finding a "middle ground" between the influence of gravity and its own angular momentum vector.