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38.8.2.2 Aerial Vehicle Navigation
ОглавлениеA UAV was flown in a cellular environment comprising three cellular CDMA BTSs and two LTE eNodeBs, whose states were estimated by mapping receivers in their environment [6]. The UAV was equipped with the cellular CDMA and LTE navigation receivers discussed in Sections 38.5 and 38.6, respectively, which produced pseudorange measurements to all five towers. The UAV was also equipped with the GRID SDR that produced pseudorange measurements to seven GPS SVs. The towers’ state estimates and GPS and cellular tower pseudoranges were used to estimate the UAV’s 3D position and clock bias through a nonlinear least‐squares estimator. Figure 38.63 illustrates the environment and the resulting 95th‐percentile uncertainty ellipsoids associated with the position estimate using (i) seven GPS SVs and (ii) seven GPS SVs along with three cellular CDMA BTSs and two LTE eNodeBs. Note that the volume of the GPS‐only navigation solution uncertainty ellipsoid VGPS was reduced upon fusing the five cellular pseudoranges to 0.16(VGPS).
Table 38.6 DOP values for M GPS SVs + N cellular towers
| (M) SVs, (N) Towers: {M, N} | {4, 0} | {4, 1} | {4, 2} | {4, 3} | {5, 0} | {5, 1} | {5, 2} | {5, 3} |
|---|---|---|---|---|---|---|---|---|
| VDOP | 3.773 | 1.561 | 1.261 | 1.080 | 3.330 | 1.495 | 1.241 | 1.013 |
| HDOP | 2.246 | 1.823 | 1.120 | 1.073 | 1.702 | 1.381 | 1.135 | 1.007 |
| GDOP | 5.393 | 2.696 | 1.933 | 1.654 | 4.565 | 2.294 | 1.880 | 1.566 |
Figure 38.62 (a) Sky plot of GPS SVs: 14, 18, 21, 22, and 27 used for the 5 SV scenarios. For the 4 SV scenario, SVs 14, 21, 22, and 27 were used. The elevation mask, elsv, min, was set to 20° (dashed red circle). (b) Top: Cellular CDMA tower locations and receiver location. Bottom: Uncertainty ellipsoid (yellow) of navigation solution from using pseudoranges from five GPS SVs and uncertainty ellipsoid (blue) of navigation solution from using pseudoranges from five GPS SVs and three cellular CDMA towers. Map data: Google Earth (Morales et al. [7]).
Source: Reproduced with permission of Z. Kassas (International Technical Meeting Conference).
