Enter the pulses per metre of the wheel speed. A value that is accurate to 10% is
sufficient unless you know the figure more accurately. The RT will improve this
scaling factor itself when GNSS is available. The Improve Configuration utility
can be used to apply a more accurate value calculated by the RT from a calibration
run. If this option is used then the RT should be allowed to recalibrate the scaling
value occasionally to account for tyre wear.
The wheel speed corrections will not be as effective in reducing the drift of the RT if
the wheel speed is measuring two wheels (i.e. after a differential), since the actual
position of the wheel is required for accurate navigation. If a post-differential encoder
must be used then the accuracy cannot be guaranteed.
For best results, a front wheel drive vehicle should be used with the wheel speed on a
rear wheel. The wheel speed pulses from driven wheels are less accurate.
Output smoothing tab
When the Kalman filter in the RT determines that there is some error to correct, this error
is applied smoothly rather than as a jump. The output smoothing controls how fast the
correction is applied to the outputs. This option is particularly useful for autonomous
vehicles or path-following robots as a rapid change in position can lead to a large change
in the steering angle.
Figure 36 shows the Output smoothing tab in the Advanced Tools section within
NAVconfig. Click the checkbox to enable output smoothing and unlock the properties for
editing.