Development of a Single Chip 6 DOF MEMS IMU for Robotic and UV Navigation

R.M. Boysel, T.E. Fiscus, L.J. Ross

Abstract:	Virtus Advanced Sensors is developing a single chip 6-degrees-of-freedom (6 DOF) MEMS IMU for use in soldier worn (or robot-mounted) systems that display the location of each wearer within a GPS-denied area and the map of the environment around the wearer. The system provides 3D mapping and localization for soldiers as they move through buildings. The soldier worn system includes a boot-mounted Personal Dead Reckoning (PDR) unit which incorporates an IMU. It is important that the size and cost of the PDR be minimized, so that it does not impede the soldier, and so that each soldier can have one. Such units would also greatly aid in the development and fielding of numerous (i.e. swarms) of miniature unmanned vehicles sent to an area to perform reconnaissance. MEMS inertial sensors are attractive for use in these types of applications requiring miniature IMUs because of their small size, and because they provide relatively high performance at low cost. However, the cost and size savings achieved by using MEMS sensors has been reduced by the need to integrate into the IMU multiple inertial sensors, all of which need to be aligned to the three orthogonal axes. The smallest MEMS IMUs currently have a volume of just under 1 in3. Furthermore, the cost of assembling and aligning the MEMS IMU can be many times the cost of the individual MEMS sensors. The single chip 6 DOF MEMS IMU being developed by Virtus is roughly the same size as, or smaller than, the individual MEMS accelerometers and gyros that make up current multi-chip IMUs. The IMU consists of a single proof mass 6 DOF MEMS motion sensor integrated into a single package with to a custom mixed signal ASIC containing capacitive drive / sense electronics and digital control and signal processing. The sensor is designed to provide inertial measurements in the +/-10 g and +/-2000 deg/sec ranges. The MEMS sensor chip is 4 mm square and 1.2 mm thick and eliminates the need for mounting sensors along multiple axes. This reduced profile IMU, when integrated with magnetometers or GPS in an Inertial Navigation Unit (INU) would in turn reduce the size of the INU. This paper describes the MEMS sensor design, fabrication, modeling, and test results.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	3930 - 3936
Cite this article:	Boysel, R.M., Fiscus, T.E., Ross, L.J., "Development of a Single Chip 6 DOF MEMS IMU for Robotic and UV Navigation," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 3930-3936.
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