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Comparison of the Trimble MX9 and the Trimble MX50 mobile mapping systems 6 Test results and conclusions Navigation performances were evaluated by comparing RMS errors in the three components, north, east and down. In particular, the first analysis focused on looking at how each system performed in real mission conditions with respect to denied GNSS conditions. This analysis was done to identify how well the IMU would have been reacting, for the specific mobile mapping system, against difficult GNSS conditions. The second analysis was done by comparing RMS values of both the MX9 and MX50 systems for the three north, east and down components. N, E, and D compared RMS values The above graphs show the magnitude of the RMS errors in the three components. It is clearly visible how better the MX9 (AP60) system controls the error in the 60 seconds of GNSS outage. Error magnitude is more than two times larger for the MX50 (AP20) system in all the three components. The drift in the solution generated by 60 seconds GNSS outage additionally has a longer duration for the MX50 system compared to the MX9 system. The IMU of the AP60 (IMU-57) navigation system in the MX9 could handle the GNSS outage conditions better in this testing scenario than the AP20 (IMU-82) navigation system of the MX50. The second analysis produced the following results: MX50 and MX9 reactions to 60 second GNSS outages In general, for the 60 seconds of GNSS denied conditions applied, the magnitude of northing drift has been very similar for both systems. Larger drift has been documented for the east and down direction for the MX50 system, as shown by the two above charts. On a motorway close to Ulm City, Germany, similar tests and analysis were also done in more favorable GNSS conditions. As expected, performances between the two mobile mapping systems were very similar, with the navigation solution mostly relying on the GNSS part of the solution. As test results confirm, the AP60 (IMU-57) of the MX9 system reacts significantly better to difficult GNSS conditions when compared to the AP20 (IMU-82) of the MX50 system. This behavior is well documented in the RMS values obtained in both the tested scenarios. In difficult GNSS scenarios, according to the application accuracy requirements, use of ground control points might be recommended. Given the better attitude in controlling the IMU drift, it is quite clear that for high absolute accuracy applications, a longer distance between GCPs (Ground Control Point) can be accepted. In the case of the MX50 system in the same conditions, a shorter distance between GCPs should be considered.

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