LiGa Microfabricated Inertial Guidance Sensor

The BMDO as part of its kinetic energy systems development requires an expendable, inertial guidance package. SatCon is proposing to develop an angular rate sensor combined with an accelerometer which are microfabricated on a single "chip" using the LIGA lithographic process. The accelerometer element employs a rebalanced cantilever, oriented orthogonally to the substrate, while the rate sensor uses a vibrating cylinder sensitive to rotation through Coriolis effects. The topology is simple but well-suited for moderate sensitivity, high shock performance. Acceleration can be sensed in two axes parallel to the substrate, while angular rate is detectable along the perpendicular axis. Only one structural layer is required, eliminating the complexity of overhanging features or structure-to-structure bonding. During Phase I, a suitable set of geometries for the combined sensor will be designed at SatCon and fabricated into test structures by our microfabrication foundry, LSU/CAMD. This will demonstrate a proof-of-principle for the mechanical and fabrication process. The designs and test results will be provided to the BMDO at tlle end of this project. A Phase I option will include production of a full set cf masks and fabrication of electrically testable structures as well as an examination of the response to electrostatic actuation. From these results an optimized mechanical and electronics design will be developed. In Phase II, prototype versions of the accelerometer structures will be fabricated from a i11 set of masks, operated with drive and sensing electronics and made available to the BMDO. The micro-fabricated inertial sensor has a simple topology, is inherently resistant to high shock, can be operated with a minimum of electronics, and is amenable to low cost production. It is an excellent solution as a key element in an inertial package wherever rugged, compact, inexpensive, moderately sensitive, or expendable devices are needed, e.g., automobile navigation systems and suspension control, robotics, in-vivo medical applications, high speed machining, and electronic parts placement machines.