Inertial sensors can be used to measure movement for a number of applications. Inertial sensors can be classified as accelerometers, gyros or inertial measurement units (IMU, a combination of both accelerometers and gyros). Virtus holds one of the largest patent portfolios in the areas of multi-axis inertial sensors including gyros and accelerometers with a particular focus on combined accelerometer/gyro motion sensors. Because of the decrease in size and cost of inertial sensors, the number of applications is growing quickly, especially in the consumer electronics field. Applications include next-generation cell phones, game controllers, pedometers, hard disk drive shock detection, GPS augmentation schemes, and automobile control enhancements, among others.
Fundamentally speaking, the heart of all MEMS gyros and accelerometers is composed of a “proof” mass. This mass moves relative to the frame of the device. That difference in movement between the frame and proof mass is related to its acceleration and can be measured in a variety of ways: capacitively, piezo-electrically, and piezo-resistively. A solid object’s movement can be fully described by measuring linear acceleration in the x, y, and z directions and angular velocity about the x, y, and z axes.