|
Table of contents
3.Introduction
4.Specification requirements
5.Solutions suggestions
6.The magnetic fields sensors
7.The inclination measurement system
8.The gyroscope
9.The data acquisition system
10.Communication system
11.The power supply
12.Realisation of the PCB
13.The embedded system
14.Static Library Util.a
15.ViewPort
16.Xcompass
17.Sensors controller commands
18.Test
19.Future improvements
20.Conclusion
21.References
The
design and the implementation of an electromagnetic compass are described in
this notes. The requirements have been almost respected and the Smart Compass
can evaluate the azimuth with 1º accuracy in normal conditions and 2.5º in
extreme conditions (for example an high tilt). We adapted the compass both to
the MMR and the SMR environment. Indoor, we have often more interference
magnetic field generated by the computer (interference detection) than outdoor
but then the ground is bumpy (tilt compensation).
Corrections
of systematic errors such alignment errors, non-linearity, and sensitivity
deviations can lead to significant improvements in the overall system
performance. With the aid of adequate feedback mechanisms (g-vector, GPS
position) and signal processing algorithms (average building, Kalman filtering)
further improvements in precision can be achieved.
The
graphical interface offers an easy way to use the device from a computer but
the main driver has been implemented on an independent library. A third program
viewport have been developed to debug the card. The driver to manage the
sensors could be easily installed on the MMR. Nevertheless, work has to be done
to realize the main application of the MMR with this device.
A
driver able to manage all this positioning system will be required, in
particular to develop a correction’s program of systematic errors. And, in
preparation of this work, a study of the different cases that could drive
different results between these systems will be useful. The knowledge of the
errors’ reason will bring an aid to design the programs, to know which device
is more accurate in the several cases, and how to correct and improve the end
position from all the results.
The
final result of the navigation’s system is an accurate compass in diverse
conditions, low cost and easy to use. |