This thesis, for the first time in literature, introduces a comprehensive study about analog
controller designs for MEMS vibratory gyroscopes. A controller of a MEMS gyroscope is
mandatory for robust operation, which is insensitive to sensor parameters and ambient con-
ditions. Errors in the controller design not only deteriorate transient performance, such as
settling time and overshoot, but also cause performance degradation due to stability problems.
Accordingly, true controller design for a gyroscope is critical work in terms of functionality
and system performance. This thesis gives details for modeling, analysis of closed-loop sys-
tems, and design procedure for drive and sense modes. Controller loops are implemented both
with discrete components and in a CMOS technology as an integrated circuit. Simulation and
test results verify the modeling, analysis, and design procedure discussed in this thesis.
Drive mode system developed previously at METU is optimized by taking circuit imperfec-
tions into account, which results in an improved transient performance of 50 msec settling
time with no overshoot for a 4&mu / m drive mode oscillation amplitude. This system has a 60
phase margin with the help of the pole-zero cancellation technique. In addition, a new gener-
iv
ation and simple drive mode controller for tactical grade applications is designed and verified
with a moderate transient performance.
Two different sense mode controller design procedures are also developed according to a new
base-band equivalent model derived for mismatch operation, as a new contribution to the
literature. Firstly, a PID controller is designed for low frequency separation between the drive
and sense modes of the gyroscope. Secondly, an integral controller is used for moderate and
high mismatch amount. The controller system designed with the new base-band equivalent
model improves the linearity, angle random walk, and bias instability by factors of 4, 9, and
3, respectively.
Proposed drive and sense mode controllers are also designed and implemented using a 0.6&mu / m
standard CMOS process. These chips are the first functional chips developed at METU de-
signed for MEMS gyroscopes. Functionality of the proposed three systems, i.e., conventional
drive mode controller, new generation drive mode controller, and sense mode controller, are
verified with tests. The first prototypes result in 0.033 degree/sqrt/(hr) angle random walk and 3 degree/hr
bias instability for open-loop operation, which is very promising and can be improved even
further in future designs.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12613017/index.pdf |
| Date | 01 February 2011 |
| Creators | Eminoglu, Burak |
| Contributors | Akin, Tayfun |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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