RASTA - real-acceleration-for-self-test accelerometer: a new concept for self-testing accelerometers

摘要

This paper reports a new innovative concept for built-in self-test systems for accelerometers. Most existing designs are based on electrostatic forces acting directly on the seismic mass, or on a thermal or piezoelectric displacement of the seismic mass. This new self-test concept is based on deliberately inducing inertial forces on the seismic mass, by imposing a known acceleration. This gives a more realistic emulation of the physical quantity that an accelerometer is supposed to measure. A "built-in shaker" is incorporated into the sensor chip. The emphasis of this contribution is on the concept of this new self-test, and on the differences with other, existing self-test systems. Furthermore, the working principle, design and fabrication of a silicon bulk micromachined accelerometer are presented. The device is the first prototype to incorporate our new self-test principles. Our intention is to use this device for a practical evaluation of the presented ideas and concepts. The sensor is fabricated in an MPW bulk micromachining process, with focused ion beam (FIB) post-processing to obtain three-dimensional features, essential to its operation. Finally, a few preliminary measurement results are added to demonstrate some of the different aspects of the device. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 14]