The gyroscope in the iPad is part of the hardware used to create Location Services, which is the iOS term for integration with geopositioning and mapping software. While GPS provide the network for location information, gyroscopes and accelerometers provide faster and more accurate data. The gyroscope is also used for software where knowing the orientation of the iPad is crucial.
A gyroscope is a spinning wheel, in a housing that can rotate in a perpendicular direction to a fixed base. It's most commonly known as a children's toy, where unlike a regular top the gyroscope's horizontal spinning wheel makes it uncommonly hard to knock over. The physical laws of angular momentum enable a gyroscope to provide precise information about forces applied against it, such as when the iPad is moved or rotated. A gyroscope provides information along a single axis (such as horizontal or vertical), so an iPad uses multiple gyroscopes to maintain three-dimensional information about itself.
In addition to the gyroscope, an iPad is equipped with an accelerometer, which measures force in a particular direction. When you stand up and start walking while carrying your iPad, the accelerometer registers an increase in speed of two or three miles per hour, while the gyroscope provides information about the direction you are traveling.
Both the gyroscope and accelerometer are crucial to Location Services, the iOS system to provide your location to mapping, geolocation and other location-based software. The GPS radio can identify a location from the satellite network, but this process takes time and is limited to a precision of 10 meters. Location Services combines this data with information about Wi-Fi hot spots to come up with a precise fix and then uses the gyroscope and accelerometer to track movement since the last fixed location. The old location, when added to velocity and direction calculations, immediately provides the current location on the iPad, which can then be double-checked against slower, networked location tracking.
Gyroscopic orientation is also important to many categories of iPad apps. Many games provide an extra control surface by measuring the entire iPad in addition to screen taps; a driving game, for example, may steer the car by rotating the entire device. Orientation is also used to measure angles in some advanced photography and 3-D apps, which records data about the iPad's position with the snapped photos.
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