A gimbal, also called a gimbal ring, is a mechanical device consisting of two or more rings mounted on axes at right angles to each other. An object mounted on a three ring gimbal will remain horizontally suspended on a plane between the rings regardless as to the stability of the base. Gimbals have a wide range of practical uses ranging from film to aerospace applications.
A gimbal may be used to keep objects level in unstable environments--for example, many dashboard mounted cup-holders are gimbals. Gimbals are also extremely valuable in shipboard and aircraft environments, when measuring instruments such as chronometers and compasses must be kept level with the horizon. Gimbals may also be used for aerospace navigation, as they can be set to provide a stable measurement from a specific reference point such as the earth or sun regardless as to their actual position in space. Gimbals employed in aerospace navigation utilize Euler angles to orient an object such as a spacecraft.
When used for aerospace navigation, gimbals are configured in sets of three gyroscopes measuring pitch, roll, and yaw. Pitch refers to rotation of the craft around the transverse axis. In the example of an airplane, the nose of the plane is pointed up to increase the pitch, and down to lower it. Roll, also know as bank, is rotation of the craft along a longitudinal axis, while yaw refers to rotation around the center of mass. The gimbals are oriented with a base, for example, the moon, and the gimbal angles measure the position of the craft relative to the base.
Occasionally, a condition known as gimbal lock can occur, when the measurement capacities of a gimbal system may be exceeded, requiring an operator to reset the gimbals. This happens when a rotation along one axis writes out another, for example when an aircraft climbs straight up into the air, making any reading of the yaw meaningless because the two axes are aligned in the same direction. Gimbal lock can be overcome with the addition of a redundant gyroscope.
Because gimbals allow objects to move through three dimensions, they are often used in film to recreate sudden motion caused by turbulence or rough seas. Gimbals also appear in situations where an object needs to pivot or swivel widely as is often the case with movie cameras or rocket engines. Gimbals are extraordinarily useful tools in a wide range of industries.