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Using the Dead Reckoning libraryΒΆ

  • First, in the Sen Examples, the aircraft example uses the Dead Reckoning library (both the DeadReckoner<T> and the SettableDeadReckoner<T>) to compute the location of the aircraft and update its FOM Spatial data accordingly.

  • Second, in the Sen Sim Tools repository, specifically in the examples section, you can find a simple example on how to use the Sen Dead Reckoning Library. We created a package called Dead Reckoning Viewer, which detects FOM objects on a Sen bus and extrapolates their location and orientation using Dead Reckoning. To run the example, configure the environment (take a look at the readme in the examples folder) and run the following command:

Run Dead Reckoning Viewer
python3 <sen_sim_tools_root>/examples/sen_dr/run_sen_dr.py

This example opens a Sen Explorer window where you can plot the smoothed position of the entity and compare it with the position received from the Sen bus. The data from the bus comes from a recording where the entity was randomly moved to generate noisy spatial data. The input data from the recording can be seen in the dr.input bus and the smoothed output in the local.output bus.

The configuration of the DeadReckoner<T> class has some parameters that the user may need to trim in some scenarios.

Consider the following recommendations:

  • If the smoothed solution becomes unstable (check the orientation, where this issue is more likely), try setting a smaller smoothingInterval, as it will prevent the acceleration predictor from overshooting.

  • If you see a lack of responsiveness in the position/orientation, try decreasing the corresponding convergence time. Keep in mind that a smaller convergence time can lead to instabilities in the smoothing algorithm.

  • If the smoothed solution is under damped and oscillates, try increasing the corresponding damping coefficient until you see these oscillations disappear.

  • Keep in mind that the Dead Reckoner works well when the updates come in at a considerable frequency (at least 20 Hz). If data is received at a slower rate, the smoothed solution could slightly oscillate around the incoming updates. This is specially observed when trying to extrapolate orientations, and the updates do not include angular velocity information.