Impact of hardware components on the precision of an UWB positioning system
Typ
Examensarbete för masterexamen
Program
Wireless, photonics and space engineering (MPWPS), MSc
Publicerad
2020
Författare
Johansson, Ludvig
Dahl, Gustaf
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The project of establishing the impact of hardware has on the precision of an UWB
positioning system was approached with broad scope. Attempting to isolate the
influence antennas- and oscillators has on the positioning precision requires a good
understanding of the hardware setup for the complete system. An UWB positioning
evaluation system was therefore designed and manufactured on PCBs, allowing it
to be modified in order to test the system performance with different antennas and
oscillators. Oscillators with three levels of frequency stability were chosen to be
evaluated. Two patch antennas, one possessing high directivity and one featuring
band-reject properties, were designed and manufactured as well. These components
effect on precision were evaluated by performing positioning in both Line-Of-Sight
(LOS)- and Non-Line-Of-Sight (NLOS) environments using different configurations
of the hardware. The results of the tests were then evaluated using several metrics
in an attempt to observe differences in the precision of the hardware configurations.
Due to limited testing and intrinsic uncertainties of the evaluation system no clear
conclusions on the isolated impact of the antennas and oscillators could be made,
nevertheless some trends could be identified. The results of the NLOS test indicate
that the band-reject properties and increased frequency stability had a positive im-
pact on precision. This effect was primarily demonstrated by the significant increase
in the number of position estimates acquired, ranging from approximately 7 up to 30
estimates depending on the hardware configuration. The higher directivity antenna
generated almost no position estimates in the NLOS test making it less suitable. The
LOS tests produced similar results for most hardware configurations with a mean
absolute deviation of the position estimates in the vicinity of 0.036 m.
A second hardware iteration, testing in a controlled environment and further analysis
of the distribution of position estimates are recognized as future improvements. To
support this, a lengthy discussion on these subjects and future work is included.
Beskrivning
Ämne/nyckelord
UWB, positioning, indoor, navigation, evaluation system, precision, antenna, oscillator.