Fig.4 - TAG and batteries supply installation for van 
experiment. 
  
Fig.5 — LN-200 IMU mounted on to the IMU-Bench prototype. 
4.2.1 Data Analysis 
Once the route was finished and the data collected, the RINEX 
and raw IMU measurements were processed in order to 
compare them with the real time solution that was also stored in 
the TAG. Some of the results of the comparisons can be seen in 
figures 6, 7, 8 and 9. 
PROCESSED OUTPUT TRACK — 1 
p — 
  
Viladecans 
    
a 
eves amet 
Castelldefels Beach 
  
1.96 1.98 2.00 2.02 2.04 
Lon(deg) 
Fig.6 — Route run by the car in the experiment 
The comparison of the trajectories shows that the difference in 
position between the two navigation solutions may vary to a 
maximum of about 15 meters (Fig.7). This is due to different 
quality of the GPS positions used in real time and in post- 
processing. The measurements took place in urban and sub- 
urban areas, where the conditions for GPS positioning are not 
optimal (satellite visibility, multipath). It is assumed, that the 
post-processing solution for the GPS trajectory is more precise. 
So, given that the GPS trajectory is an important part of the 
navigation processing, the cause of difference in position is 
known. 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part Bl. Istanbul 2004 
  
~ END POINT 
1.97 1.57 un , 1.084 
Fig.7- Zoom of experiment route. In Red it is marked the real 
time solution, for comparison purposes. 
For the attitude angles the performance in part is good. The 
maximum difference between the real time and the post- 
processed pitch and roll is about 0.2 degrees (Fig.9). The 
heading varies about | degree, which is again due to the 
imprecision of the real time GPS trajectory when working in 
urban environments. That trajectory is internally used by the 
navigator for self-calibrating of the heading gyro. 
290F T T 
  
r4 y 
Fig.8 - Real time solution of heading angle. 
j 
v des. v À * PM Nf Ss ORE, eunt 1 
& : A : s i 
i V | 
| 
rv 4 
v se LA 
manette, i 
ms A ng | 
È 1 
E i 
E 1 
È j 
| 
Fig.9 - Comparison of attitude angles between real time 
solution and post-processed solution. The black line 
is heading, the red one is pitch and the blue one is 
roll. 
Only a short analysis of the results could be carried out for this 
paper. We will conduct a more detailed analysis in the close 
future. 
4.4 Future experiments 
In addtion to this, TAG is also being used in GeoPIE project, 
where it is helping to develop the navigation model of a remote 
sensor. In this case, two flights have been carried out with the 
     
     
    
   
  
   
   
      
   
   
    
   
    
   
   
    
  
  
    
      
    
   
    
    
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