North finding with a single double mass MEMS gyroscope- A performance demonstrator
Daniel Bülz, Roman Forke, Karla Hiller, Sebastian Weidlich, S. Hahn, Alexey Shaporin, Dirk Wünsch, Stefan Konietzka, Tim Motl, Detlef Billep, Harald Kühn
Abstract
North-finders based on angular rate sensors have an advantage over magnetic compasses or GPS (global positioning system) as they are insensitive against local Earth magnetic field variations and independent of electromagnetic transmission. In exchange, very precise and stable gyroscopes are needed to resolve the Earth’s angular rate for north-finding with sufficient accuracy. Therefore, a north-finder is a very good example to demonstrate the advancement in MEMS gyroscope development taking place over the last decade up to a point, where it is possible to reliably determine north-direction with a single fully integrated high precision sensor in a simple system. The north-finder presented in this paper uses the Maytagging algorithm, which enables the use of standard consumer grade mechanical and electrical components. The sensor used, is an in-house developed tuning fork MEMS gyroscope with integrated signal conversion. The paper introduces the basic technology for fabricating the MEMS element, as well as improvements which are planned in the future to enhance the sensitivity even more. The noise and drift of the sensor is low enough to determine the north heading in Chemnitz (at a latitude of $50.8^{\mathrm{o}}$) down to $5^{\mathrm{o}}$ of standard deviation in less than 1.5 minutes. This can be even improved down to 1° by quadrature compensation as will be discussed in this publication as well.