Novatel OM-20000141 Navigation Mode, Data Collection, Inssolutiongood, Solution Parameters

Chapter 3 SPAN Operation

3.2.2Navigation Mode

Once the alignment routine has successfully completed, SPAN enters navigation mode.

SPAN computes the solution by accumulating velocity and rotation increments from the IMU to generate position, velocity and attitude. SPAN models system errors by using a filter. The GNSS solution, phase observations and automatic zero velocity updates (ZUPTs) provide updates to the filter. Peripheral updates can also be supplied; wheel sensor for displacement updates or an external receiver for heading updates.

Following the alignment, the attitude is coarsely defined, especially in heading. Vehicle dynamics, specifically turns, stops and starts, allow the system to observe the heading error and allows the heading accuracy to converge. The amount of dynamics required for filter convergence vary by the alignment quality and maneuvers performed. The INS Status field changes to INS_SOLUTION_GOOD once convergence is complete. If the attitude accuracy decreases, the INS Status field changes to INS_HIGH_VARIANCE. When the accuracy converges again, the INS status continues as

INS_SOLUTION_GOOD.

3.2.3 Data Collection

The INS solution is available in the INS specific logs with either a standard or short header. Other parameters are available in the logs shown in Table 5, Solution Parameters.

	Table 5: Solution Parameters
Parameter			Logs
Position		INSPOS or INSPOSS		INSPOSX or INSPVAXa
		INSPVA or INSPVAS
		INSVEL or INSVELS		INSVELX or INSPVAXa
Velocity		INSSPD or INSSPDS
		INSPVA or INSPVAS
Attitude		INSATT or INSATTS		INSATTX or INSPVAXa
		INSPVA or INSPVAS
Solution Uncertainty		INSCOV or INSCOVS

a. These logs contain variance information and are therefore large logs. Use a low logging rate (<20 Hz) only.

Note that the position, velocity and attitude are available together in the INSPVA, INSPVAS or INSPVAX logs.

The inertial solution is available up to the rate of the IMU data. Data can be requested at a specific rate up to the maximum IMU output rate (125 or 200 Hz) or can be triggered by the mark input trigger at rates up to 20 Hz.

The GNSS-only solution is still available through the GNSS-only logs such as RTKPOS and PSRPOS. When running SPAN, rates of non-INS logs should be limited to a maximum rate of 5 Hz. Refer to the OEM6 Family Firmware Reference Manual (OM-20000129) for more details on these logs. INS-only data logging and output can be at rates of up to the rate of the IMU data.

 Ensure all windows, other than the Console, are closed in NovAtel Connect and then use the SAVECONFIG command to save settings in NVM. Otherwise, unnecessary data logging occurs and may overload the system.

32 SPAN-IGM User Manual Rev 2