Motion processing characterizes measures and intelligent processing of three dimensional (3D) movements. Motion processing technology has become the technological milestone that drives User Interface (UI) innovations in Consumer Electronic (CE) product design. Motion processing function promises to become the “must have” feature able to convert any standard handset into 3D intelligent equipment extending the means of how the user can interact with the mobile device. Adaptation of motion processing technology delivers new user experiences and functions to mobile handsets through enhancing web and multimedia navigation, providing Optical Image Stabilization (OIS), Location Based Services (LBS), mobile 3D gaming, and many other applications.
Motion Processing Implementations
Common methodology used for motion processing applications assumes measurements and processes of linear and rotational movements with use of accelerometer, magnetometer or a gyroscope. Accelerometers provide information about linear movement as a sum of linear and centripetal acceleration affected by the gravity and vibration. Extraction of a single element from the linear motion information given by accelerometer requires an addition of device able to provide detailed information about rotational movement. The most intuitive solution providing rotational movement information required for complete motion processing solution is magnetometer. Unfortunately its’ output data is relative to magnetic north. Moreover magnetometer is prone to be affected by external magnetic fields sources and has limited ability to respond to fast rotational movements. Thus the key technology commonly used for measurement of angular rate of rotation is a gyroscope. The gyroscope is the only inertial sensor providing accurate and latency free rotational movement information without being affected by gravitational, magnetic or other external factors.
Application Note: InvenSense ARM Reference Board
CE Targeted Gyroscope
The only technology feasible for measures of absolute rate of rotation suitable for consumer grade products is the gyroscope based on Micro-ElectroMechanical Systems (MEMS) technology. Only MEMS device can overcome limitations such as large dimension and fragile structure of the conventional attitude indicator. Another factor making MEMS devices very attractive for CE market is relatively low price of MEMS based gyroscope with accuracy comparable with the conventional rotating one. Typical MEMS implementations use miniaturized structures vibrating in the plane which will be rotated. The Coriolis effect implicates an acceleration of the vibrating proof masses during rotation. This causes out of plane motion (deflection) of vibrating structure during rotation which is detected by transducer. The resulting signal produce voltage that is proportional to the angular rate. It is that so because detected Coriolis acceleration arising in a rotating reference frame is proportional to the angular velocity which specifies the angular speed and the axis about which the object is rotating.
Application Note: ITG-3200 3-Axis Gyro Evaluation Board