VBOX IISX – Triple Antenna (VB20SL3)

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Vbox SL3

VBOX IISX – Triple Antenna (VB20SL3)

The VBOX IISX is a powerful instrument used for measuring the speed, position and angle of a moving vehicle. It is based on a new generation of high performance satellite receivers, and will measure acceleration figures, braking distances, lap times, cornering forces, slip angle, pitch angle and more.
The Triple Antenna version of the VBOX IISX has all of the same features as the single and dual antenna versions, but contains three GPS engines configured in a ‘fixed baseline RTK setup’. This allows extra parameters to be measured which are not normally available from a single point GPS setup.
These parameters include Slip angle, Pitch angle and Roll angle, which are all measured simultaneously.

How Does it Work?

The Three Axis unit uses the same methods to measure pitch, roll and yaw angles as the VBOX IISX Dual antenna.

3-Antennae1The exact distances between the primary antenna and the two additional antennas are entered into the unit, which then uses these ‘fixed baselines’ to enable an RTK technique which can measure the relative height and position of each antenna to a remarkable accuracy.
This is possible because similar errors are present at each antenna, so a sophisticated algorithm is able to eliminate these errors, resulting in a very precise relative height and position measurement.

3-ant_roof_annotated_sThe picture on the right demonstrates a typical setup, where antenna A is the primary antenna. In this instance, antennas A & C are measuring roll angle, whilst antennas A & B are measuring both yaw angle and pitch.
The exact distances between A & B and A & C have been measured and entered into the VBOX via the front panel. Note that the slip angle depends on where the measurement is taken, imagine turning a sharp corner very slowly, the front of the car will be showing a large negative slip angle value due to the steering input, and the rear of the car will show very little slip angle.
Racelogic  SLIP VBOXThe slip angle also varies across the width of the car, so it is important to place the antenna directly above the point at which you wish to measure this angle. Ground plane Antennas can be mounted outside of the body of the vehicle using a suitable mount.
The VBOX has been configured with the distance between the antennae, and thanks to this layout is able to record all the measurements as shown in the table below.

 

 

Antenna Combinations True
Heading
Slip
Angle
Pitch
Angle
Yaw
Rate
Lateral
Velocity
Roll
Angle
A no no no no no no
A + B yes yes yes yes yes no
A + C no no no no no yes
A + B + C yes yes yes yes yes yes

How accurate are the results?

The accuracy of the slip, pitch and roll angles depend on the separation of the antennas and the quality of the antennas which are used.

The wider the separation of the antennas, the better the accuracy you will achieve:

Separation Slip angle Pitch angle Roll Angle
0.5m 0.5° rms 1.0° rms 1.0° rms
1.0m 0.25° rms 0.5° rms 0.5° rms
2.0m 0.1° rms 0.25° rms 0.25° rms

We supply propriety, magnetic mount, ground plane antennas which have been optimised for use in this application to give the best results.

To obtain these accuracies, the distance between the antennas needs to be accurate to within 0.5cm, and the system used in a clear, open area without any trees, tall masts, fences or buildings nearby.

What can I use it for?

The Triple Antenna VBOX IISX can be used for all of the same tests as the normal VBOX IISX, but in addition:

  • Dynamic Tests – Slip, pitch and roll angles updated at 20Hz alongside speed, distance & acceleration
  • Steady State Cornering – Slip angle without any drift or correction over time
  • Trailer Angles – Measure relative angles between two fixed bodies (two systems required)


Racelogic VBOX MarineWe also offer a marine version: 

The Marine version of the VBOX IISX is supplied in a Waterproof enclosure with an integrated battery pack.
Three GPS engines are utilised to measure speed, acceleration, position and all 3 attitude angles; pitch, roll and yaw (alternatively known as trim, heel and leeway).

For More information about the Marine version Click Here