The robot is equipped with an acceleration sensor to detect and identify the robot's posture, 

collisions and other sudden external conditions, sudden speed changes, etc. 

This time, I will introduce you to the gyro sensor. Let's learn about the principle of gyro sensors and gyroscopes!

What is a gyro sensor?

Gyro sensor

Gyro sensor is a simple and easy-to-use positioning and control system based on free space movement and gestures.

Gyro sensor principle

The principle of gyro sensor is that as long as the direction indicated by the rotation axis of the rotating object 

is not affected by external forces, it will not change. Based on this principle, people use it to maintain direction. 

Then, the direction indicated by the axis is read using a variety of methods, and the data signal is automatically 

sent to the control system.

Modern gyroscopes are instruments that can accurately determine the orientation of moving objects. 

Traditional inertial gyroscopes are mainly mechanical gyroscopes. Mechanical gyroscopes have high 

requirements for process structures and complex structures, and their accuracy is restricted by many 

aspects. Currently, fiber optic gyroscopes, ring laser gyroscopes and modern integrated vibration gyroscopes 

are more commonly used.

Where can the same force as a person be issued? Who can rotate without thrust?

Gyro sensor principle

Think of the wheel below that rotates in the y-axis direction. The angular velocity vector and angular 

momentum vector of this wheel both point to the y-axis. Now, this turntable rotates in the direction 

of the z-axis. In other words, what kind of additional force needs to be provided at the moment of standing on the turntable?

After a very short time t, the y rotation axis tries to rotate a large angle in the z-axis direction. 

This system has a lot of angular momentum, which occurs in the rotation of the y-axis. 

Why do I say this, because when the y-axis moves, the angular momentum also changes.

 In this case, in order to prevent the size of the angular momentum from changing, 

when only the direction is rotated, the change in angular momentum l is L=L, 

and the corresponding torque of the angular momentum change is =l/t=l/t=l. 

Taking into account the direction of all these vector equations, it can be expressed as follows.

Take the wheel back to the state of standing on the disc again. 

In case the wheel and l are prevented from being on the horizontal plane, 

they will be guided to the vertical direction. In order to generate this magnitude of torque, 

the value needs to be effective. To do this, horizontal forces f and -F need to be applied 

on both sides of the shaft. Where does this force come from? 

In any case, this force must be generated by the person who lifts the wheel.

However, here, according to Newton's third law, when a force is applied to an object, 

the same force is applied in the opposite direction of the force, 

so the same magnitude of torque is applied in the opposite direction through rotational dynamics. 

The disk and the person rotate in a circular direction perpendicular to the center.

Application of gyroscope sensor

The modern gyroscope is an instrument that can accurately determine the orientation 

of a moving object. It is an inertial navigation instrument widely used in modern aviation, 

navigation, aerospace, and defense industries. Its development is of great strategic 

significance to the development of a country's industry, defense, and other high-tech technologies.

The above is an introduction to the principles of gyroscope sensors and gyroscopes.

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Overview of gyro sensors

A gyro is a device that detects angular motion of a high-speed rotating body relative to the inertial 

space around one or two axes orthogonal to the axis of rotation.

The main part is a rotor that rotates at a high angular velocity about the axis of rotation, 

and the rotor is mounted in a bracket. Angular motion detection devices made using other 

principles that perform the same function are also called gyroscopes.

For those who are not familiar with such products, gyro sensors are easy-to-use positioning 

and control systems based on free space motion and gestures. Flick the mouse on an imaginary plane, 

and the cursor on the screen will follow it. You can draw a circle around the link and click the button. 

These operations can be easily achieved when you are speaking or leaving the table. 

Gyro sensors were initially used in helicopter models, and are now widely used in mobile and 

portable devices such as mobile phones (IPHONE's three-axis gyro technology).

Characteristics of gyro sensors

First of all, the most important characteristics of gyro sensors are its stability and precession.

We can find from the ground gyroscopes played by children that high-speed gyroscopes can 

remain vertical without falling and remain perpendicular to the ground, which reflects the stability 

of the gyroscope when moving. The theory of studying the motion characteristics of gyroscopes is 

a branch of the dynamics of rigid body motion around a fixed point. It studies the dynamic characteristics 

of rotating objects based on the inertia of objects. It can be said that the gyroscope sensor is a simple and 

easy-to-use positioning control system based on free space motion and gestures.

Application of gyroscope sensors

1. Defense industry

Gyroscope sensors were originally used in helicopter models and are now widely used in mobile and 

portable devices such as mobile phones. Not only that, modern gyroscopes are instruments that can accurately 

determine the direction of moving objects, so gyroscope sensors are indispensable control devices in modern navigation, 

aerospace and defense industry applications. 

The gyroscope sensor was named by French physicist Leon Foucault when he studied the rotation of the earth. 

It has always been a convenient and practical reference instrument for attitude, speed, etc. for aviation and maritime navigation.

2. Door opening alarm

New application of gyro sensor: measure the door opening angle, and when the door is opened to a certain angle, 

an alarm will be sounded, or combined with the GPRS module to send a message to remind the door to open. 

In addition, the gyro sensor integrates the function of the acceleration sensor. When the door is opened, 

a certain acceleration value will be generated. The gyro sensor will measure this acceleration value. 

When the preset threshold is reached, an alarm will be sounded. Or combined with the GPRS module to send 

a message to remind the door to open. The alarm can also be integrated into the radar sensing measurement function, 

mainly when someone enters the room and moves, it will be measured by the radar. Double insurance anti-theft, 

high reliability, low false alarm rate, very suitable for anti-theft alarms in important occasions.

Gyro sensors are an easy-to-use positioning and control system based on free space motion and gestures. 

Initially applied to helicopter models, they are now widely used in mobile portable devices such as mobile phones.

For those who are not familiar with this type of product, gyro sensors are an easy-to-use positioning and 

control system based on free space motion and gestures. Swing the mouse on an imaginary plane, 

the cursor on the screen will move with it, you can circle around the link, and click keys. 

These operations are easy to achieve when you talk or leave the table. Gyro sensors were initially applied to helicopter models, 

and have been widely used in mobile portable devices such as mobile phones.

Gyro sensors are an easy-to-use positioning and control system based on free space motion and gestures. 

Swing the mouse on an imaginary plane, the cursor on the screen will move with it, you can circle around the link, 

and click keys. These operations are easy to achieve when you talk or leave the table.

The principle of the gyroscope is that the direction of the axis of rotation of a rotating object will not change 

when it is not affected by external forces. Based on this principle, people use it to maintain their direction. 

Then, the direction indicated by the axis is read by various methods, and the data signal is automatically transmitted to the control system.

Gyro sensor principle: The principle of the gyroscope is that the direction pointed by the axis of 

rotating object will not change when it is not affected by external forces. According to this principle, 

people use it to maintain direction, and the thing made is called a gyroscope. When the gyro sensor works, 

it needs to be given a force to make it rotate quickly, which can reach hundreds of thousands of revolutions 

per minute and can work for a long time. Then, the direction indicated by the axis is read through various methods, 

and the data signal is automatically transmitted to the control system.

Gyro sensors can sense the changing dimensions of spatial displacement in all aspects, and have been used in aviation, 

aerospace, navigation and other fields earlier. With the decline in the cost of gyro sensors, many smartphones now 

integrate gyro sensors, so what is the role of gyro sensors in mobile phones?

The gyro sensor in the mobile phone is first used for navigation. If the gyroscope is used in conjunction with the 

GPS in the mobile phone, its navigation ability will be greatly improved. In fact, many professional handheld GPS 

are also equipped with gyroscopes. If the corresponding software is installed on the mobile phone, 

its navigation ability is no less than that of the navigators used on many ships and aircraft.

Secondly, the gyroscope sensor can also be used in conjunction with the camera in the mobile phone, 

which will prevent the photo effect from deteriorating when the hand shakes.

Third, the enhanced mobile game reflects the flight game, sports game, and even some shooting games 

from the first perspective. The gyroscope sensor can fully monitor the displacement of the player's hand, 

thereby achieving various game operation effects. The gyroscope sensor can also be used as an input device, 

equivalent to a 3D mouse, which enhances the gaming experience.

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In fact, a gyroscope generally refers to a gyroscope with symmetry. Its mass distribution is uniform, 

its shape is symmetrical with the axis, and the axis of rotation is the axis of symmetry. 

The rotational torque or rotational moment is constant and always rotates around the next axis. 

With the advancement and development of science and technology, people have manufactured 

gyroscopes with various functions based on the mechanical properties of gyroscopes.

The principle of the gyroscope is that the direction of the rotation axis of a rotating object 

will not change without the influence of external forces. According to this principle, 

people use it to maintain the direction, and what they make is called a gyroscope.

Gyroscopes are precision devices used to measure the angular motion of high-speed

rotating objects and the momentum sensitive housing around one or two axes orthogonal 

to the axis of rotation in relative inertial space.

We actually use this principle when riding a bicycle. The faster the wheel turns, the less likely it is to fall down, 

because the axle has a force to keep it horizontal. When the gyroscope is working, it should be given a force to 

make it rotate quickly. Generally speaking, it can reach hundreds of thousands of revolutions per minute and can work for a long time.

Traditional inertial gyroscopes mainly refer to mechanical gyroscopes. 

Mechanical gyroscopes have high requirements for process structures and complex structures, 

and their accuracy is limited in many aspects. Since the 1970s, 

the development of modern fiber optic gyroscopes has entered a new stage.

In 1976, experts put forward the basic idea of modern fiber optic gyroscopes. 

After the 1980s, modern fiber optic gyroscopes developed rapidly. 

At the same time, laser resonant gyroscopes have also made great progress. 

Due to the advantages of compact structure, high sensitivity and reliable operation, 

fiber optic gyroscopes have completely replaced traditional mechanical gyroscopes in many fields 

and become key components of modern navigation instruments.

In addition to ring laser gyroscopes, there are also modern integrated vibration gyroscopes developed at 

the same time as fiber optic gyroscopes. Integrated vibration gyroscopes have the characteristics 

of high integration and small size, and are also an important development direction of modern gyroscopes.

Today, gyroscopes are widely favored in military, scientific and technological research and applications. 

For example: gyroscope nutation, shell flipping, azimuth indicator, gyrocompass, etc. In addition, 

gyroscopes are widely used in fighter air combat aiming, high-rise building tilt monitoring, robot balancing, 

high-speed train damping control, and long-span bridge health status monitoring.

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Classification of inertial navigation

Platform type

According to the different coordinate systems established, it is divided into two working modes: 

space stability and local level. The platform of the space-stabilized platform inertial navigation system 

is relatively stable in the inertial space and is used to establish an inertial coordinate system. 

The influence of the earth's rotation and gravity acceleration is compensated by the computer. 

This inertial navigation system is mostly used for launch vehicles and the active parts of some spacecraft. 

The characteristic of the local horizontal platform inertial navigation system is that the reference plane 

formed by the two accelerometer input axes on the platform can always track the horizontal plane of the 

point where the aircraft is located (using accelerometers and gyroscopes to form a Shura ring to ensure), 

so the accelerometer is not affected by gravity acceleration. This inertial navigation system is mostly used 

for aircraft (such as airplanes, etc.) that move at a uniform speed along the surface of the earth. 

In the platform inertial navigation, the frame can isolate the angular vibration of the aircraft, 

and the instrument working conditions are better. The platform can directly establish a navigation coordinate system, 

with a small amount of calculation and easy compensation and correction of the instrument output, 

but the structure is complex and the volume is large.

Strapdown type

According to the different gyroscopes used, it is divided into rate-type strapdown inertial navigation 

system and position-type strapdown inertial navigation. The former uses a rate gyro to output an 

instantaneous average angular velocity vector signal; the latter uses a free gyro to output an angular displacement signal. 

Strapdown inertial navigation does not require a platform, has a simple structure, a small size, and is easy to maintain. 

However, the gyroscope and accelerometer are directly installed on the aircraft, and the working conditions are poor, 

which will reduce the accuracy of the instrument. The output of the accelerometer in this system is the acceleration 

component of the body coordinate system, which needs to be converted into the acceleration component of the navigation 

coordinate system by a computer, and the amount of calculation is large.

In order to obtain the position data of the aircraft, the output of each measurement channel of the inertial navigation should be integrated. 

The drift of the gyroscope will increase the angle measurement error in proportion to time, 

and the constant error of the accelerometer will cause a position error proportional to the square of time. 

This is a divergent error (increasing with time), which can be corrected by forming three negative feedback loops: 

Shura loop, gyrocompass loop and Foucault loop to obtain accurate position data.

Shura circuit, gyrocompass circuit and Foucault circuit all have the characteristics of undamped periodic oscillation. 

Therefore, inertial navigation is often combined with radio, Doppler, astronomical and other navigation systems to 

form a high-precision combined navigation system, which enables the system to have both damping and error correction functions.

The navigation accuracy of the inertial navigation system is closely related to the accuracy of the earth's parameters. 

A high-precision inertial navigation system should use a reference ellipsoid to provide parameters of the earth's shape and gravity. 

Due to factors such as uneven crust density and terrain changes, the actual values of the parameters at each point on 

the earth often differ from the calculated values obtained from the reference ellipsoid, and this difference is also random. 

This phenomenon is called gravity anomaly. The gravity gradiometer under development can measure the gravity field in real time, 

provide earth parameters, and solve the problem of gravity anomaly.

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Inertial navigation is based on Newton's inertial principle, using inertial elements (accelerometers) 

to measure the acceleration of the carrier itself, and obtain the speed and position through integration and calculation, 

so as to achieve the purpose of navigation and positioning of the carrier.

At present, inertial navigation can be divided into two categories: platform inertial navigation and strapdown inertial navigation. 

The main difference between them is that the former has a physical platform, and the gyro accelerometer is placed on a platform stabilized by a gyro. 

The platform tracks the navigation coordinate system to achieve speed and position resolution, 

and the attitude data is directly taken from the platform's ring frame; in strapdown inertial navigation, 

the gyro and accelerometer are directly fixed to the carrier. The function of the inertial platform is completed by a computer, 

so it is sometimes called a "mathematical platform", and its attitude data is obtained by calculation. Inertial navigation has a fixed drift rate, 

which will cause errors in the movement of objects. Therefore, long-range weapons usually use instructions, GPS, etc. 

to make regular corrections to inertial navigation to obtain continuous and accurate position parameters.

 For example, the mid-range air-to-air missile uses strapdown inertial navigation + command correction in the middle section, 

JDAM uses autonomous satellite positioning/inertial navigation combination (GPS/INS), 

Tomahawk also uses GPS/INS+ terrain matching technology, and most launch vehicles use platform inertial navigation.

The mechanism of the inertial navigation system has developed a variety of methods such as flexible inertial navigation, 

fiber optic inertial navigation, laser inertial navigation, micro-solid-state inertial instruments, etc., 

which are widely used in various aspects of aviation, aerospace, navigation and land mobility according to different environments and accuracy requirements.

In principle, the inertial navigation system is usually composed of an inertial measurement device, a computer, 

a control display, etc. The inertial measurement device includes an accelerometer and a gyroscope, 

also known as an inertial navigation combination. The three-degree-of-freedom gyroscope is used to 

measure the three rotational motions of the aircraft; the three accelerometers are used to 

measure the acceleration of the three translational motions of the aircraft. The computer calculates 

the speed and position data of the aircraft based on the measured acceleration signal. 

The control display displays various navigation parameters. According to the installation method of 

the inertial navigation unit on the aircraft, it is divided into platform-type inertial navigation system

 (the inertial navigation unit is installed on the platform of the inertial platform) and 

strapdown inertial navigation system (the inertial navigation unit is directly installed on the aircraft); 

the latter omits the platform, so the structure is simple, the volume is small, and the maintenance is convenient, 

but the instrument working condition is not good (affecting the accuracy) and the calculation workload is large.

Advantages

(1) Since it is an autonomous system that does not rely on any external information and does not radiate 

energy to the outside, it has good concealment and is not affected by external electromagnetic interference;

(2) It can work all day, all the time, in the air, on the surface of the earth, and even underwater;

(3) It can provide position, speed, heading and attitude angle data, and the navigation information generated 

has good continuity and low noise;

(4) The data update rate is high, and the short-term accuracy and stability are good.

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In the popular navigation field, inertial navigation has always occupied an important position. 

It is a navigation system with inertial measurement units such as gyroscopes and accelerometers as sensitive devices. 

On the basis of initial measurement data such as angular velocity and linear acceleration, 

by establishing a model coordinate system and algorithm, the speed, displacement, 

heading angle and other information of the measured object can be calculated. 

Compared with other modern navigation technologies, it is self-measured and has the characteristics of high concealment.

Principle of inertial navigation: Use inertial elements to measure the acceleration of the vehicle itself, 

and obtain the speed and position through integral calculation, so as to achieve the purpose of vehicle navigation and positioning. 

It is a technology that measures the acceleration of the aircraft, automatically performs integral calculations, 

and obtains the instantaneous speed and position data of the aircraft. The components are all installed on the carrier. 

It is an autonomous navigation system because it does not rely on external information or radiate energy to the outside world, 

and is not easily interfered. It is usually composed of inertial measurement devices, computers, control displays, etc.

What are the advantages of inertial navigation? Let me introduce them to you.

1. Strong concealment. The inertial navigation system is a completely autonomous navigation system. 

It will neither affect the external environment nor be interfered by the external electromagnetic field. 

Based on this, it is also a very reasonable choice in highly confidential fields such as national defense and military.

2. Longevity. It has a low bit error rate and can work for a long time in the sky, on the ground, and in the water. 

In addition, its endurance is long and can almost be done all day in the field.

3. Accurate data. It can derive a lot of accurate information, such as position, speed, navigation angle, etc., 

based on a small amount of measurement status information, which can effectively ensure the stability and consistency 

of data transmission within a certain period of time.

The navigation accuracy of the inertial navigation system is closely related to the accuracy of the earth's parameters. 

It needs to use a reference ellipsoid to provide the shape and gravity parameters of the earth. 

Due to factors such as uneven crust density and terrain changes, there are often differences between the actual values of 

the parameters at various points on the earth and the calculated values obtained by the reference ellipsoid, 

and this difference is also random. This phenomenon is called gravity anomaly, but the gravity gradiometer 

under development can measure the gravity field in real time, provide earth parameters, and solve the problem 

of gravity anomaly. Through the above analysis, the advantages of the inertial navigation system are compared. 

In the future production and use process, we can make a reasonable choice based on actual requirements and economic conditions. 

Only in the correct use process can its power be brought into play.

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Inertial navigation is an autonomous navigation method that uses two inertial sensors, a gyroscope and an accelerometer, 

to measure the acceleration and angular velocity of a ship. It is usually composed of an inertial measurement device, 

a computer, a control display, etc. The inertial measurement device includes an accelerometer and a gyroscope, 

also known as a combination. The three-degree-of-freedom gyroscope is used to measure the three rotational motions of the aircraft. 

The three accelerometers are used to measure the acceleration of the three translational motions of the aircraft. 

The computer calculates the speed and position data of the aircraft based on the measured acceleration signal, 

controls the display to display various navigation parameters, and realizes the function.

What are the categories of inertial navigation? Let me introduce them to you.

1. Platform type. According to the different coordinate systems established, it can be divided into two working modes: 

space stability and local level. The space stability platform is stable relative to the inertial space. 

The inertial space is used to establish the inertial coordinate system. 

The influence of the earth's rotation and gravity acceleration is compensated by the computer. 

This system is mostly used in the active section of launch vehicles and some spacecraft. 

The characteristic of the local level inertial navigation system is that the reference plane formed by the 

two accelerometer input axes on the platform can always track the horizontal plane of the aircraft's point 

(this is guaranteed by the Shula loop formed by the accelerometer and the gyroscope), so the accelerometer is not affected by gravity acceleration. 

This system is mostly used for aircraft (such as airplanes.) Moving at the same speed along the surface of the earth, 

in which the frame can isolate the angular vibration of the aircraft, the instrument works well, 

it can directly establish the navigation coordinate system, and it is easy to compensate and correct the instrument output, 

but the structure is complex and the volume is large.

2. Inertial navigation: strapdown. According to the different gyroscopes used, it can be divided into rate 

strapdown inertial navigation system and position strapdown inertial navigation system. 

The former uses the rate gyroscope to output the instantaneous average angular velocity vector signal, 

and the latter uses the free gyroscope to output the angular displacement signal. 

The strapdown inertial navigation system omits the platform, so it has a simple structure, small size, and easy maintenance. 

The gyroscope and accelerometer are directly installed on the aircraft. The harsh working conditions will 

reduce the accuracy of the instrument. The accelerometer of this system outputs the acceleration component 

of the fuselage coordinate system, which needs to be converted into the acceleration component of 

the navigation coordinate system by a computer, so the amount of calculation is large. In order to obtain the 

position data of the aircraft, it is necessary to integrate the output of each measurement channel of the inertial 

navigation system. The drift of the gyroscope will increase the angle measurement error over time, 

and the constant error of the accelerometer will cause the square error of the position over time. 

This is a divergent error (increasing over time), which can be corrected through three negative feedback loops: 

the Shula loop, the gyroscope loop, and the Foucault loop to obtain accurate position data.

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From 1910 to the present, the development of gyroscopes has gone through four generations. 

The first generation is ball bearing supported gyroscopes, the second generation is liquid floating gas floating gyroscopes, 

the third generation is flexibly supported (that is, the support position is allowed to have a certain deformation) rotor gyroscopes, 

and the fourth generation includes electrostatic gyroscopes, laser gyroscopes, fiber optic gyroscopes and MEMS gyroscopes, etc. 

There may be superconducting gyroscopes in the future. 

1. Electrostatic gyroscopes (also known as electrostatic (suspended) gyroscopes) use the strong electric field in

2. ultra-high vacuum to generate supporting force, replacing the three pairs of mechanical bearings of the gyro

3. motor and the universal bracket to form an ideal bearing system, that is, a bearing with neither mechanical

4. contact nor gas resistance. After the gyro rotor is accelerated to the required speed, the acceleration power supply is cut off,

5. and the rotor will rotate for a long time under the action of inertia.

6. 
   

Since the electrostatic gyroscope uses non-contact support and there is no friction, it has high accuracy and a drift rate 

as low as 0.0000000001°/h (weightless environment in space). It is suitable for long-term working environments, 

but cannot withstand large shocks and vibrations. The structure and manufacturing process are complex and the cost is high. 

The main foreign countries that developed electrostatic gyroscopes are the United States, France and Russia. 

In 1976, Tsinghua University successfully developed an electrostatic gyroscope three-axis stabilized platform, 

as shown in the figure below. 2. Laser gyroscope Laser uses the Sagnac effect in optics to measure the rotational motion of the carrier. 

The Sagnac Effect is a rotatable annular interferometer invented by Sagnac in 1913. 

A beam of light emitted by the same light source is decomposed into two beams, 

which are allowed to circulate in opposite directions in the same loop for one week and then meet, 

and then interference is generated on the screen. When there is an angular velocity of rotation in the plane of the loop, 

the interference fringes on the screen will move. This is the Sagnac effect. Simply put, 

when the annular optical path does not rotate relative to the inertial space, 

the length of the clockwise and counterclockwise optical paths is the same. 

When the annular optical path has an angular velocity ω relative to the inertial space, 

the propagation time of the clockwise and counterclockwise signals is different, so the angle can be calculated.

The laser gyroscope has a large dynamic range and high-speed characteristics, high accuracy, 

short startup time, high reliability and long life. The disadvantages are the existence of lock-up phenomenon 

(below a certain low angular velocity, it is insensitive to angular velocity, that is, it cannot be measured), 

expensive price and large size. The following are the parameters of the typical long-endurance laser gyro strapdown 

inertial navigation system (Strapdown). A variety of technical means can improve the accuracy of laser gyro navigation, 

among which the rotation modulation technology is one of the core technologies, that is, 

the introduction of additional mechanical rotation in the inertial navigation system, 

so that the navigation error caused by the error of the inertial device can be offset within a rotation cycle. 

3. Fiber optic gyro Fiber optic gyro (FOG) uses the same principle as the laser gyro, that is, the Sagnac effect to measure angles. 

But unlike the laser gyro, the fiber optic gyro uses a section of fiber ring to replace the original optical path. 

Optical fiber can be wound, and its optical path is greatly increased compared to that of laser gyroscope, 

which improves the detection sensitivity and resolution by several orders of magnitude and overcomes the 

locking phenomenon of laser gyroscope. Its advantages are no moving parts, low price, short startup time, 

wide dynamic range, and it is a strapdown inertial navigation system sensor with strong competitiveness and a wide market.

Its disadvantage is that it is greatly affected by temperature. 

The long-term zero-bias stability of high-precision fiber optic gyroscopes publicly reported abroad has reached the order of 0.00001°/h. 

The main research and development units include iXBlue of France and Honeywell of the United States. 

iXBlue has improved the accuracy of fiber optic gyroscopes by increasing the diameter of the fiber optic ring (from 9 cm to 50 cm or even 200 cm), 

increasing the length of the fiber optic (from 5 km to 15 km), and adopting relative intensity noise (RIN) suppression measures. 

Its latest design of interferometric fiber optic gyroscope with a diameter of 200 cm and a length of 15 km can meet the positioning 

requirements of 1nm (nautical mile)/60d of high-precision fiber optic inertial navigation systems.

The figure below is a prototype of the "reference-level 0.00003°/h" fiber optic gyroscope developed by Honeywell. 

The diameter of the gyroscope is 27 inches and the length of the fiber optic ring is 8 kilometers. 4. MEMS gyroscope MEMS, 

or mechanical electronic system, is a new generation of micro-electromechanical devices processed using nanotechnology. 

It is a vibration angular rate sensor. Its basic principle is to excite one vibration mode to another vibration mode, 

and its amplitude is proportional to the input angle. The main foreign research and development companies include Sperry, 

Draper Laboratory, General Electric, Watson and Texas Instruments in the United States. The advantages of MEMS are low cost, 

small size, and a wide market. The disadvantage is high processing technology. 

The following table shows the main parameters of MEMS gyroscopes of various levels. 

5. Summary In summary, we have roughly drawn a simple conclusion: 

1) The electrostatic gyroscope has the highest accuracy. According to its 0.0001°/h, speed of 30nm (nautical miles)/h, 

and 60d of navigation, the theoretical positioning error is 0.08nm/60d. 

2) Fiber optic gyroscope is second, and the interferometric fiber optic gyroscope with a diameter of 200cm and

 a length of 15km can meet the 1nm/60d navigation requirement. 

3) The second is the laser gyroscope, and the two-axis laser gyroscope can reach 0.071nm/d, and 60 days is 4.3nm/60d. 

4) MEMS gyroscope is the worst.