Filtered acceleration outputs from RTs

Product News

October 11, 2011

The acceleration measurements of the RT products can now be filtered before they are output. This removes vibration from the acceleration measurements so that the underlying acceleration can be seen more easily.

The accelerometers in the RT have a high bandwidth and are very sensitive. On a moving vehicle the acceleration measurements can often appear noisy but this is just an accurate reflection of the actual motion of the RT. The RT is able to react to changes in acceleration quickly, which is needed so that the timing of the motion is not disturbed but it also means that vibration is seen clearly.

By filtering the acceleration outputs, the vibration in the RT’s output is reduced and the underlying acceleration due to the motion of the vehicle can be seen more clearly. However, real-time filters introduce delays and the acceleration output will now be delayed. RT-Config, which can be used to configure the acceleration filter, shows the delay in the output caused by the selected filter so that this can be compensated later on.

The filtering affects the CAN bus and RT-ANA acceleration outputs. The Ethernet output is not filtered but the filter characteristics are output as part of the Status Messages and the latest NCOM decoders can filter the accelerations. Enginuity and RT Post-process both output filtered accelerations when they are available. RT-View doesn’t currently display the filtered accelerations but will be updated in the future.

The acceleration filters are configured in RT-Config. There are separate options to configure the linear accelerations and the angular accelerations so that they can have different filters applied to them. The vehicle-frame and level-frame accelerations both use the same filter characteristics and cannot be controlled independently.

For more information on how the RT products measure acceleration please contact support.