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FCW - Multi-Target (Moving Base)

Multiple Vehicle Targets

This mode facilitates the ability for vehicle separation parameters to be calculated at the Subject vehicle with respect to two Target vehicles.

This system consists of a VB3iSL-RTK in each Target vehicle and a VB3iSL-RTK in the Subject vehicle. 

NOTE: It is not possible to operate in Duplex mode with multiple Target vehicles.

High accuracy of the vehicle separation calculations is made possible by the use of a Moving Base solution.

Moving Base solution removes the need for a fixed Base Station to obtain accurate GPS position, thereby allowing vehicle separation testing to be carried out in real world environments and without the restrictions of Base Station radio range.

The Target VBOX (tracked vehicle) will also log the normal GPS data to a .vbo file, so that the files from each VBOX can be compared in the VBOX Tools Graph screen or VBOX Test Suite Chart screen. This is useful to see the relative positions.

Configuration of the VBOX’s is done through VBOX Manager (RLVBFMAN).  

Hardware Configuration

The following diagrams show the recommended hardware configuration for each Vehicle. The items greyed out are not essential but many customers may find them beneficial.

 

Please ensure that all vehicle antennas are correctly positioned and connected.

Subject Vehicle

 

Target Vehicle

VBOX Configuration

This guide assumes the use of a moving base solution.

Target Vehicle 1

1. Connect VBOX Manager to the VBOX in Target Vehicle 1.
2. Enter the setup menu of VBOX Manager.
3. Select the 'VBOX' option.

4. Select 'LOG RATE' and set the rate to '100 Hz', then select 'BACK' to return to the 'VBOX' setup menu.

5. Select 'DYNAMICS' and set the dynamic mode to 'NORMAL', this Dynamics mode is best for ADAS tests, return to the 'VBOX' setup menu.

6. Select 'DGPS' and set the DGPS mode to 'MB Rover', return to the 'VBOX' setup menu.

7. Select 'DGPS RS232 Rate' and select the appropriate settings for your radios, return to the 'VBOX' setup menu.

Note: To ensure that the VBOX receives the DGPS correction signal, the correct RS232 rate must be set. All Racelogic blue boxed radios use 115200 kbit/s, Satel grey boxed radios use either 19200 kbit/s or 38400 kbit/s.

8. Return to the main setup menu and select the 'ADAS' option, then select 'MULTI. TARGET' mode.

9. Select 'TARGET VEHICLE 1' and return to the 'ADAS' setup menu.

Target Vehicle 2

1. Connect VBOX Manager to the VBOX in Target Vehicle 2.
2. Repeat steps 2 – 8 in section ‘Target Vehicle 1' above.

3. Select 'TARGET VEHICLE 2' and return to the 'ADAS' setup menu.

Subject Vehicle

1. Connect VBOX Manager to the VBOX in the Subject Vehicle.
2. Repeat steps 2 – 5 in section ‘Target Vehicle 1' above.

3. Select 'DGPS' and set the DGPS mode to 'MB Base', return to the 'VBOX' setup menu.

4. Select 'DGPS RS232 Rate' and ensure that '115200' is selected, return to the 'VBOX' setup menu.

5. Select 'MULTI. TARGET' mode and select 'SUBJECT VEHICLE', return to the 'ADAS' setup menu.
RTK Status Indication
As the Subject Vehicle effectively becomes the Base Station it will not physically go into an RTK lock, therefore the 'DIFF' LED of the Subject VBOX will NOT illuminate. The 'DIFF' LED of the Target VBOX’s should gain RTK FIXED status indicated by the 'DIFF' LED illuminating green.

For Multiple-Target mode, you must use radio modems programmed with different configuration scripts. It is not possible to use the normal ADAS link radios.

The Radios at each TARGET VBOX need to be set to CLIENT mode and paired to the singular ADAS radio at the subject vehicle.

The radio at the subject vehicle needs to be set to SERVER and BROADCAST mode

  1. Ensure the 2.4 GHz telemetry modems are connected as shown in subject vehicle configuration and target vehicle configuration.

  2. As 2.4 GHz transmissions are very direct, with a narrow beam width, care needs taking when mounting the antenna; ensure they are:

  • On the highest part of the vehicle roof

  • Away from any nearby obstructions that could cause a potential blockage to the path of the signal

  • Mounted vertically to ensure maximum transmission power in the horizontal plane

  • Mounted at least 50 cm away from other Radio antennas

When the 2.4 GHz modems are connected correctly the 'SER' light on the SUBJECT VBOX will illuminate, indicating the reception of a serial data stream.

ADAS 1.jpg
ADAS 2.jpg

Pre-Test Configuration

Setting The Contact Points

After selecting the Subject Vehicle in either the multi or single target modes, the user can set the contact points by entering the ‘CONTACT POINTS' Menu.
A.png

In this menu, it is possible to define contact points for either the ‘Subject Vehicle’ or ‘Target Vehicle’. You can manually configure up to 2 contact points by entering a numerical offset, or you can set up to 24 contact points by using a GPS antenna.
B.png

Manually Entering Contact Points
 
C.png

Select either 'SUBJECT VEHICLE' or 'TARGET VEHICLE' in the contact points menu.

Select 'ENTER POINTS'.

 
 
 
Select 'NO. OF POINTS'.  
 
 
This menu allows the user to select whether 1 or 2 contact points are to be specified. The current number of selected points is highlighted with a tick next to the number. Selecting a different number will move that tick to that number. Select 'BACK' once completed. OffsetNew.png
Select 'POINT 1' to specify first contact point. 
E.png This menu allows the user to translate the antenna point to a desired reference point on the vehicle. This is done by entering a numerical longitudinal (‘LNG RANGE’) and lateral (‘LAT RANGE’) offset value.
F.png Selecting ‘LNG RANGE' allows the user to enter a longitudinal offset, with a forward offset being POSITIVE and a rearward offset being NEGATIVE. Pressing ‘APPLY’ will store the value.
G.png Selecting ‘LAT RANGE' allows the user to enter a lateral offset, with a rightwards offset being POSITIVE and a leftwards offset being NEGATIVE. Pressing ‘APPLY’ will store the value. Select 'BACK' to return to the previous menu. 

If the user selected 2 contact points in NO. OF POINTS, POINT 2 will be displayed on the menu. Select ‘POINT 2' and repeat the above process.

Repeat this process to define the other vehicle.

Setting Up To 24 Contact Points

 

First, connect a ground plane antenna to the VBOX.
Select either 'SUBJECT VEHICLE' or 'TARGET VEHICLE' in the contact points menu. Select 'SET POINTS'.
I.png
Using the survey pole, move the antenna to the desired contact point on the vehicle. Ensure there is a fixed RTK solution and select 'SET POINT'.
If successful, VBOX Manager will display 'POINT 1 SAVED'.
If there is no RTK fix, the point will not be saved and VBOX Manager will display 'POINT 1 NOT SET, NOT RTK FIXED'.
J.png
To set the next point, move the antenna to another desired point of contact and repeat the process. Repeat this process until all the desired points are set, or a limit of 24 is reached.
Once all the desired points are set, move the antenna to the location of antenna A and select 'SET ANT A'.
K.png
Then move the antenna to the location of Antenna B and select 'SET ANT B'. This process can be repeated to define the other vehicle.
If multiple points have been set on either vehicle, the calculated ADAS parameters (range, angle etc) will always reference the nearest surveyed point.
L.png
Saving Vehicle Contact Points
After the required contact points have been surveyed, it is possible to save these points to the compact flash card by selecting 'SAVE'.
M.png
This allows the user to either overwrite a previously saved file, or create a new save file using the '{CREATE NEW}' option.
N.png
Selecting the '{CREATE NEW}' option will display an alpha numeric scroll wheel where the user can enter the desired file name.
O.png
Once entered, VBOX Manager will display the ‘SAVE SUCCESSFUL' message.
P.png
Loading Vehicle Points
Select either 'SUBJECT VEHICLE' or 'TARGET VEHICLE' in the contact points menu. Then select 'LOAD'.
Q.png
This will bring up a list of all previously saved files, which the user can select to load.
R.png
If successful, VBOX Manager will display 'LOAD SUCCESSFUL'.
S.png

Smoothing

If the box is set into twin antenna mode, the smoothing menu will not be present as the calculations will run off of the True heading provided by the twin antenna lock.

It is recommended that if user intends to set multiple points on the car, they enable the dual antenna.

There are two configurable variables linked to heading smoothing; ‘Smoothing Distance’ and ‘Speed Threshold’. Due to the nature of the vehicle separation measurement and calculation process many channels are derived using the heading of the vehicle which can inherently be noisy. To overcome this heading can be smoothed with a dynamic smoothing routine.

Smoothing Distancesmoothing 1.png

The vehicle heading is normally calculated between the current and previous sample. Even with the stability of RTK position GPS position can vary by a few millimetres with respect to the original. When the travelled distance between subsequent samples is short (low speeds) this leads to a potential larger potential error in the calculated heading.

 

This smoothing routine allows the user to force a ‘Smoothing Distance’ over which heading is calculated. This is therefore dynamic, resulting in a variable number of samples used to determine the smoothing level on the heading; the lower the speed the more samples that are used. With 100 Hz logging and a smoothing distance of 1 m at 72 km/h, the heading is calculated over the previous 5 samples, whilst at 15 km/h the heading would be calculated over the previous 26 samples.

Above: Shows the improvement on vehicle heading from using smoothing distance

Setting A Smoothing Distance

1. Using VBOX Manager, go to the 'ADAS' menu and go to the 'MULTI. TARGET' menu and select 'SUBJECT VEHICLE'.

2. Select ‘SMOOTHING' from the 'SUBJECT VEHICLE' menu.

3. Select ‘SMOOTHING DIST' and enter the smoothing option for the Subject Vehicle, from the options between 0.00 m and 2.00 m.

4. For typical Vehicle Separation applications we recommend a smoothing distance of 1 m.
Speed Threshold

Due to the nature of how heading is calculated, even when Smoothing is applied at very low speeds and when the vehicle is stationary the heading channel can become very noisy and unusable, this in turn results in many of the Vehicle Separation channels becoming noisy at low speed and unusable when stationary. This is solved by fixing the heading below a configurable Speed Threshold.

1. To set the speed threshold repeat steps 1 and 2 above, then select 'SPD THRESHOLD' and enter the speed threshold option for the Subject Vehicle.

2. We recommend a Speed Threshold of 5 km/h.
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Last modified
15:54, 21 Mar 2017

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