LOW-COST SIX DEGREE OF FREEDOM INERTIAL MEASUREMENT UNIT

Development of a low-cost six degree of freedom inertial measurement unit on single silicon chip for use in evaluation injury potential of aircraft crew escape systems is proposed. The design is based upon the silicon micromachining technology developed by Waddan Systems. The highly integrated chip utilizes three multisensors and one accelerometer to yield the six acceleration components. In a multisensor a pair of silicon accelerometers are made side by side with their input axes parallel to each other. They are interconnected by an electrostatically driven dither mechanism perpendicular to the input axes. A linear acceleration input produces the same response in both the devices, but an angular rate normal to the linear acceleration input axes produces equal but opposite Coriolis components in the accelerometers. By adding and subtracting the accelerometer output signals, one measures both the linear acceleration and the angular rate applied to the multisensor. The angular rate along with a clock input yields the angular acceleration. The device has both military and commercial applications.