Gun hard inertial measurement unit based on MEMS capacitive accelerometer and rate sensor

Abstract

Smart munitions and missiles are increasingly incorporating inertial measurement units for guidance of short range weapon systems. In addition to usual high performance of the required sensors, namely, accelerometers and gyros, this application requires high shock survivability and post shock stability of the sensors. Colibrys has successfully developed a gun hard version of its accelerometer product and AIS has integrated these acceleration sensors and rate gyro to a gun hard IMU. The IMU has been extensively tested and characterized over the full temperature range, at Aerobutt and in many live shooting trials. The extreme shock performance of the IMU has been maintained by making the accelerometer shock resistant. This has been achieved by placing a specially designed mechanical stopper over the sensing element to protect the sensor from extreme shock levels by limiting the mechanical displacement of the MEMS element. This approach has resulted in excellent post shock performance of the acceleration sensor. Beyond this a special assembly technology has been developed at AIS to ensure that key shock components are filtered out and their energy is not transferred into the sensing element; and the vibrating elements are not affected by the components of the firing shock.