Nov 17, 2017

Towed Trailer Articulation Measurement

We have recently been asked to measure the articulation of a trailer and a towing vehicle.

A VBOX3iSL Twin Antenna system was mounted on the trailer with an IMU co-located with the primary antenna.

This setup supplies the heading, pitch, roll and YAW of the trailer at any speed.

The towing vehicle was then fitted with a similar system.

So two files are created - one by each VBOX. Now, obviously the two files cannot be started at exactly the same time so some post processing has to take place in VBOX File Processor (available FoC from


One of the functions of File Processor is to combine two separate files using the very accurate time stamp from GPS. Another function is to provide maths channels.  The result is a single file with the articulation angle calculated that can be shown alongside any of the other standard VBOX and IMU channels.

In the screen dump below, the top graph is the speed of the tow vehicle, the middle graph is the articulation angle between the tow vehicle and the trailer and the bottom graph is the true heading of the tow vehicle.  One aspect that is shown here is that when the tow vehicle heads past 360 deg. the articulation angle is still calculated correctly.

If you would like to know more about this application, please contact us on 07774149266.

VBTS Screen Dump

And another display showing articulation angle and the two channels that have created it shown together with the pitch angle from the IMU and the twin antenna setup without any calibration: