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MeasurementAccuracy / AttitudeAccuracy-INSOptionOnly

Attitude accuracy (INS option only)

SPEEDBOX-INS Attitude Accuracy Test

In order to test the accuracy of our SPEEDBOX INS attitude measurements (roll, pitch and yaw) the units were tested against a navigation grade RLG IMU with two military GPS receivers providing both standard GPS and GPS compass information. Additionally the reference system GPS solution was post processed with corrections gathered at a reference station, resulting in a cm-level accuracy GPS solution aiding the tactical-grade IMU. The complete reference system cost in excess of $500K.

The reference system is permanently and accurately installed in the testing vehicle for optimum measurement precision. The SPEEDBOX-INS systems were additionally fitted to the vehicle ready for testing and data collection.

Open-sky high dynamics test

High dynamics tests were performed in open-sky conditions (good GPS conditions). These conditions would be applicable to many tests for which the system is intended; including stability testing, slip angle measurement and vehicle dynamics development. In a large open and clear area figure of eights were driven at a demanding pace. This test was repeated multiple times.


The headline 1-sigma comparison figures for both the standard SPEEDBOX-INS and the tactical grade SPEEDBOX-INS versus the reference system during this test are shown below:

Standard Dual Antenna SPEEDBOX-INS System Tactical Dual/Single Antenna SPEEDBOX-INS System
Roll 0.1 0.04
Pitch 0.1 0.04
Yaw 0.15 0.08

Representative yaw, pitch and roll output from the standard SPEEDBOX-INS is shown below compared to the reference solution.

Roll

Above: Roll output (SPEEDBOX-INS Tactical Dual Antenna system compared to reference system)

Above: Roll output (SPEEDBOX-INS Tactical Single Antenna system compared to reference system)


Above: Roll output (SPEEDBOX-INS Standard Dual antenna system compared to reference system)


Pitch

Above: Pitch output (SPEEDBOX-INS Tactical Dual antenna system compared to reference system)


Above: Pitch output (SPEEDBOX-INS Tactical Single antenna system compared to reference system)


Above: Pitch output (SPEEDBOX-INS Standard Dual antenna system compared to reference system)


Yaw

Above: Yaw output (SPEEDBOX-INS Tactical Dual antenna system compared to reference system)


Above: Yaw output (SPEEDBOX-INS Tactical Single antenna system compared to reference system)


Above: Yaw output (SPEEDBOX-INS Standard Dual antenna system compared to reference system)


Error Distribution

Please note that the pitch and roll measurements are calculated in exactly the same way, and as such we would expect to see very similar error distributions for both measurements. However as can be seen below the pitch appears to significantly more accurate than the roll measurement, resulting in a double peak distribution. The reason for this is that the reference system and our SPEEDBOX-INS systems are mounted at different locations on the test vehicle. As the test vehicle was driven in a figure of 8 pattern, the forces enacting on vehicle are twisting it one way, then the other; and due to this the 2 systems saw slightly different roll angles. On the pitch axis the vehicle is much stiffer and you cannot see the same effect.

Above: Distribution of difference in measurements between the SPEEDBOX-INS Dual Tactical and the reference system


Above: Distribution of difference in measurements between the SPEEDBOX-INS Single Tactical and the reference system


Above: Distribution of difference in measurements between the SPEEDBOX-INS Dual Standard and the reference system

Page last modified on May 16, 2014, at 11:11 AM