**Abstract**

Gyroscope is a type of angular velocity measuring device, which can precisely determine the orientation of moving objects. It was first employed in navigation and later became an inertial navigation instrument widely used in modern aviation, aerospace, and national defense industries. As a vital representative of gyroscope, the fiber-optic gyroscope (FOG) has advantages in terms of compact structure, high precision, high sensitivity, and high environmental adaptability. FOG has been broadly utilized in many fields, and is also a key component of modern navigation instruments. In this paper, the history, classification, performance indicators, and application requirements of gyroscope are briefly summarized. The development history of FOG based on Sagnac effect is described in detail. The three generations of FOG are interferometric FOG, resonant FOG, and stimulated Brillouin scattering FOG. At the same time, this chapter summarizes the development and research situation of FOG in the United States, Japan, France, and other major developing countries, and compares the application of FOG in various international companies.

**Keywords:** gyroscope, fiber-optic gyroscope, navigation, survey

#### **1. Gyroscope**

#### **1.1 Development of gyroscope**

At the beginning of the eighteenth century, human beings discovered that the rigid body with fast rotation has fixed axis and precession. Nowadays, gyroscope is generally used to measure angular velocity and displacement in relative inertial space. In 1765, Leonhard Euler, a Russian mathematician and physicist, published the article "The Theory of Rigid Body Moving around Fixed Point," and established the basic mechanics theory of Rotor Gyroscope. Then, the dynamic equation of rigid body rotation was deduced, which laid a solid foundation for the study of gyroscope theory. In 1778, Lagrange, a French scientist, established the differential equations of motion of a rigid body rotating at a fixed point under the action of gravitational moment in his book "Analytical Mechanics." In 1852, French physicist Foucault, based on the theory of rigid body motion put forward by predecessors, combined with his in-depth study of rigid body, first discovered that the rotor rotating at high speed in the middle of the earth always pointed to a fixed direction because of inertia, and created a measuring device for verifying the rotation of the earth [1], which was named as Gyroscope. This creates a precedent for the research and development of engineering practical gyroscopes [2]. H. Anschutz and Sperry

produced Gyrocompasses which were mainly applied in navigation for ships at sea [1] in 1908 and 1909. The emergence of gyrocompass marks the formation of gyroscope technology and the opening of its modern application, which pushes the theoretical research of gyroscope to practical application.

### **1.2 Classification of gyroscope**

According to the working principle of gyroscope, it can be divided into classical mechanics-based gyroscope and modern physics-based gyroscope.

Based on the different medium of angular velocity of sensitive carrier relative to inertial space, gyroscopes can be categorized into rotor gyroscopes, optical gyroscopes, magnetohydrodynamic gyroscopes, and atomic gyroscopes in engineering. The most common rotor gyroscopes include liquid-floated gyroscopes, dynamically tuned gyroscopes, electrostatic gyroscopes, and vibration gyroscopes. Optical gyroscopes include laser gyroscopes, fiber-optic gyroscopes, and micromachined gyroscopes include MEMS gyroscopes that have been applied in engineering [3].

## **1.3 Performance indicators and application requirements of gyroscope**

In order to analyze and evaluate the overall performance of gyroscope, a series of criteria should be formulated to provide reference for its application. Generally speaking, the main indicators of gyroscope performance are scale factor


#### **Table 1.**

*The classification of performance indicator in gyroscope.*

**25**

*On the Development and Application of FOG DOI: http://dx.doi.org/10.5772/intechopen.88542*

[4] and fiber-optic gyroscopes (FOG) [5].

**2. Fiber-optic gyroscope**

**2.1 Development history of FOG**

stability, drift stability, random walk, range and cost, etc. According to these indicators, gyroscopes are divided into four categories: strategic level, inertial navigation level, tactical level, and commercial level, as shown in **Table 1** [3]. **Figure 1** presents the applications and requirements of different gyroscope technologies. Almost half of the high-performance gyroscope market is covered by national defense applications, while commercial aviation accounts for 25% of the market. At present, there are mainly two mature optoelectronic technologies in these two market areas, namely ring laser gyroscope (RLG) based on Sagnac effect

In the 1970s, FOG was first proposed and studied [6]. Then, its emergence has opened the way for the research of all solid-state sensors. It was initially considered to be devoted to medium-level applications. But over time, it has made a number of outstanding achievements in theoretical research and engineering [7]. Nowadays, FOG has reached the strategic level of performance and surpassed the ring laser gyroscope in terms of deviation noise and long-term stability. Its advantages are becoming more obvious, and its application fields are becoming more extensive. It

In 1913, French physicist G. Sagnac presented a new theory through a considerable amount of experiments. The phase shift of two beams propagating along the closed optical path is proportional to the normal input angular rate of the closed optical path. That is the Sagnac effect [8]. Successful application of inertial navigation technology during World War II made FOG more challenging. In the early inertial navigation system, the sensor system used stable platform. With the progress of science and technology and the emergence of artificial satellite, people put forward the concept of strapdown inertial navigation, which has the characteristics of simple structure, small size, light weight, low cost, and easy maintenance. Sensitive devices are becoming more and more demanding. After World War II, gyroscopic technology has developed rapidly. In 1963, SePoy Gyroscope Company made a breakthrough in the area of optical gyroscope. The first experiment demonstrated ring laser gyroscope. Thereafter, after nearly 20 years of efforts, the inertial ring laser gyroscope has become practical. In 1983, Honeywell's ring laser gyroscope was installed in the airborne strapdown inertial navigation system of the new passenger aircraft Boeing 767 and 757. The rapid development of optical fiber communication, fiber optics, and laser technology has promoted the further development of optical rotation sensor based on Sagnac interferometer. In the mid- and late 1970s, a new

has gradually become the key development goal for each country.

type of optical gyroscope, named fiber optic gyroscope, appeared.

proposed the hypothesis of using optical fibers in gyroscopes [4]. In 1976, American scientists Victor Vali and Richard W. Shorthill tested the hypothesis of G. Pincher and G. Herpner, which symbolized the transition from theoretical stage to practical stage of FOG [9]. In 1978, McDonald Company developed the first practical FOG, and in 1980 Bergh et al. produced the first all-fiber optic gyroscope test prototype, making FOG a big step toward practicality [10]. In the mid-1980s, the interferometric fiber optic gyroscope was successfully developed. The development and application of optical gyroscope is an important milestone in the history

Scientists Macek and Davis confirmed the correctness and realizability of ring laser gyroscopes in 1963. In 1967, the French physicists G. Pincher and G. Herpner

**Figure 1.** *The application requirements of different FOGs.*

#### *On the Development and Application of FOG DOI: http://dx.doi.org/10.5772/intechopen.88542*

*Gyroscopes - Principles and Applications*

**1.2 Classification of gyroscope**

**Performance indicator Strategic** 

*The classification of performance indicator in gyroscope.*

produced Gyrocompasses which were mainly applied in navigation for ships at sea [1] in 1908 and 1909. The emergence of gyrocompass marks the formation of gyroscope technology and the opening of its modern application, which pushes the

According to the working principle of gyroscope, it can be divided into classical

Based on the different medium of angular velocity of sensitive carrier relative to inertial space, gyroscopes can be categorized into rotor gyroscopes, optical gyroscopes, magnetohydrodynamic gyroscopes, and atomic gyroscopes in engineering. The most common rotor gyroscopes include liquid-floated gyroscopes, dynamically tuned gyroscopes, electrostatic gyroscopes, and vibration gyroscopes. Optical gyroscopes include laser gyroscopes, fiber-optic gyroscopes, and micromachined gyroscopes include MEMS gyroscopes that have been applied in engineering [3].

theoretical research of gyroscope to practical application.

mechanics-based gyroscope and modern physics-based gyroscope.

**1.3 Performance indicators and application requirements of gyroscope**

**level**

In order to analyze and evaluate the overall performance of gyroscope, a series of criteria should be formulated to provide reference for its application. Generally speaking, the main indicators of gyroscope performance are scale factor

Scale factor stability/ppm <1 1–100 100–1000 >1000 Drift stability/(°)·h<sup>−</sup><sup>1</sup> <0.01 0.01–0.15 0.15–15 >15 Random walk/(°)·h<sup>−</sup><sup>1</sup> <0.01 0.01–0.05 0.05–0.5 >0.5 Range/(°)·s<sup>−</sup><sup>1</sup> >500 >500 >400 50~1000 Cost/\$ 20,000 10,000 1000 500

**Inertial navigation level**

**Tactical level**

**Commercial level**

**24**

**Figure 1.**

**Table 1.**

*The application requirements of different FOGs.*

stability, drift stability, random walk, range and cost, etc. According to these indicators, gyroscopes are divided into four categories: strategic level, inertial navigation level, tactical level, and commercial level, as shown in **Table 1** [3].

**Figure 1** presents the applications and requirements of different gyroscope technologies. Almost half of the high-performance gyroscope market is covered by national defense applications, while commercial aviation accounts for 25% of the market. At present, there are mainly two mature optoelectronic technologies in these two market areas, namely ring laser gyroscope (RLG) based on Sagnac effect [4] and fiber-optic gyroscopes (FOG) [5].
