Two-axis gimbals were in use in China (for carry-ing liquids with less sloshing) around the beginning of the Current Era. Gimbaled inertial navigation systems using feedback control technology were first developed around the middle of the twentieth century, when computers were too slowfor strapdown calculations and too heavy for in ight applications.Gimbalsare nested ringlike structures with orthogonal rotation bearings (also called gimbals) that allow isolation of the inside from rotations of the outside. Three sets of gimbal bearings are sufficient for complete rotational isolation in applications with limited attitude mobility (e.g., surface ships), but applications in fully maneuverable hosts require an additional gimbal bearing to avoid the condition, known as gimbal lock,in which the gimbal configuration no longer provides isolation from outside rotations about all three axes. Gyroscopes inside the gimbals can be used to detect any rotation of that frame due to torques from bearing friction or load imbalance, and torquing motors in the gimbal bearings can then be used to servo the rotation rates inside the gimbals to zero. For navigation with respect to the rotating earth, the gimbals can also be servoed to maintain the sensor axes fixed in locally level coordinates.Two-axis gimbals were in use in China (for carry-ing liquids with less sloshing) around the beginning of the Current Era. Gimbaled inertial navigation systems using feedback control technology were first developed around the middle of the twentieth century, when computers were too slowfor strapdown calculations and too heavy for in ight applications.Gimbalsare nested ringlike structures with orthogonal rotation bearings (also called gimbals) that allow isolation of the inside from rotations of the outside. Three sets of gimbal bearings are sufficient for complete rotational isolation in applications with limited attitude mobility (e.g., surface ships), but applications in fully maneuverable hosts require an additional gimbal bearing to avoid the condition, known as gimbal lock,in which the gimbal configuration no longer provides isolation from outside rotations about all three axes. Gyroscopes inside the gimbals can be used to detect any rotation of that frame due to torques from bearing friction or load imbalance, and torquing motors in the gimbal bearings can then be used to servo the rotation rates inside the gimbals to zero. For navigation with respect to the rotating earth, the gimbals can also be servoed to maintain the sensor axes fixed in locally level coordinates.
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