**Lianqun Zhou**

**1**

**Chapter 1**

Applications

**1. Origins of gyroscopes**

and navigation systems.

**2. Development process of gyroscopes**

Introductory Chapter:

Gyroscopes - Principles and

*Xuye Zhuang, Pinghua Li, Dongxing Li and Wentao Sui*

In ancient China, dating back to 500 BC, an interesting toy called "bamboo dragonfly" was invented to emulate the dragonfly [1]. The toy was very popular among children. When they rubbed this toy between their hands, it went flying into the air. Children had great fun experimenting to see whose bamboo dragonflies would fly the farthest and the highest. Bamboo dragonfly is an early type of gyroscope owning a history longer than 2500 years. But the name "gyroscope" did not appear until in the middle of 19th century. Gyroscope was created by a French physicist, Jean-Bernard-Léon Foucault [2]. He named his experimental instrument for Earth's rotation observation by joining two Greek roots: gyros meaning "circle or rotation" and skopeein meaning "to see." During his experiment to demonstrate the Earth's rotation, he found gyroscopes could maintain their original orientations in space regardless of Earth's rotation. This unique merit made gyroscopes are the perfect sensors to detect and measure the angular velocity of a rotational object, the deviation of a vehicle from its desired orientation. Since then gyroscopes were widely used in autonomous navigation systems. According to Encyclopedia Britannica, the first workable gyrocompass was developed by German inventor H. Anschütz-Kaempfe in 1908 [3]. It was invented to be used in a submersible. Then, in 1909, the first auto-pilot was created by an American inventor Elmer A. Sperry. It consisted gyroscopes which used to measure the rotation speed of the airplane. By collecting this information, gyroscopes could help stabilize the flight of the aircraft. In 1916, gyroscopes were used for assistant steering in a Danish passenger ship of a German company. Since then, gyroscopes became more and more popular in attitude control

The prototypes of gyroscopes designed by Léon Foucault were mechanical gyroscopes. The typical type of this kind of gyroscope was made by suspending a spinning relatively massive rotor inside three rings called gimbals. The basic principle of mechanical gyroscopes was the law of conservation of angular momentum: the tendency for the spin of a system to remain constant unless subjected to external torque. Mechanical gyroscopes are the most common or familiar type of gyroscope. Bamboo dragonfly fits into this category, which includes any gyroscope that relies on a ball bearing to spin. These types of gyroscopes are often used in navigation of aeronautic devices and vessels. However, due to the friction in the support bearings,

CAS Key Laboratory of Biomedical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, China
