**1. Origins of gyroscopes**

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 and navigation systems.
