Letter 34664 August Fastrack

[Hardingfv32]

Maybe I do not get it but can someone explain how Flagtronics activates only the units in the area of the yellow flag incident. Can not get it straight. Thanks

Are you talking about an specific car on track? Software... Say the base station knows everything about every inch of the track and every individual car positions, speed, etc. on the track. Integrate all this information and constantly radio communicate with every individual car to tell the FT200 what it should be displaying at the moment in time or location. I would say not the most difficult programing task compared to what else is going on in the world.

Brian

[Steve Davis]

Each FT incar unit has a GPS tracker and reports it's position back to the FT control computer (periodically .. I have seen NO data about how often that occurs .. but would guess it might be in the multi-millisecond range. but not nearly fast enough to provide 'lap times' any closer than hundreths.. likely no more than TENTHS of a second.. or even slower). A lot of that depends on the latency of the comms to/from the car. It is a PACKETIZED system.. mean the car prepares a datapacket that includes all the data that it needs to send to control and sends it. That packet has to be ACKNOWLEDGED as properly recieved and gets retransmitted if NOT received without error - so has to be sent again. Same for info back from Control. SO.. that means a potential of several tx/rx per report.. during which the car has already MOVED from that location and is now somewhere else. I can see the car receiving the flag change within .. oh... maybe 1 or 2 seconds of passing the perimeter on average. SOME will be spot on... some will be delayed. Will also be subject to just how many cars are in the immediate vicinity of each other.

Before FT shows up at an event, they program the perimeters of every corner station - both coming and going - presumably using SCCA input and site lines (geo considerations). During the event, the master FT computer (located in the tower) compares the GPS location of EVERY CAR on track continuously. Then compares each car's location to the perimeter locations in real time.. then broadcasts any required flag conditions BACK to the cars that are affected... or so it's supposed to work. In addition the FT200 will be further delayed by the corner station having to WAVE the flag and ACTIVATE the flag condition ... and that has the same latency as the car comms... but would only have to TX a smaller packet. It's location is KNOWN and CONSTANT.. the only thing needed would be the assigned corner ID and flag condition.

I'm sure it's quite the software task to keep up with all that, but using > and < I can see how it could work.. within limitations. Probably takes more computing speed than can be provided by your 'average PC' though. There is also the delay (not ZERO) in getting the info from and back to the car.. and the car being in a position to receive the info and update the incar display.

I have raised the question with FT and they report that "it's adequate".

I'll be studying my incar video from the Sebring Race 2 where I encountered a yellow entering T3 lefthander (SHOULD have been WAVING for many seconds, but I could not be sure if it was stationary or not). I SAW the flag at the station, but did NOT see any change in the FT display. The corner station is "in my view... kinda" approaching the turn. The FT display is INSIDE my cockpit and is NOT "in my view" as I approach the corner.. at speed...with 3 other cars around me. The FT display, however IS in view of my camera, so I'll see it if it was there .. unless my arm happened to be blocking at that moment.

Seems to me that the best utility of the FT, at least for formula cars, is in presenting the Code/35 .. or whatever speed they decide on... to tell (COMMAND!) the drivers to SLOW DOWN NOW after an FCY is called ... and, possibly to present a new GREEN when the FCY is concluded. At this point, with so few cars equipped with FT, it's not very useful... nor is compliance required - it's just INFORMATIVE .. until the FT becomes MANDATORY at the Runoffs this year.

I remains to be seen just HOW effective it will be.. and HOW SCCA will use it to implement DISCIPLINARY ACTIONS. I would suggest that everyone that installs one, try your best to get it into view of your camera - maybe even HARDER than getting the display into DRIVER VIEW. I can see this thing becoming a real can of worms when SCCA decides to start using it for CSA actions....and you KNOW they will.

Steve, FV80

[Hardingfv32]

Before FT shows up at an event, they program the perimeters of every corner station - both coming and going - presumably using SCCA input and site lines (geo considerations). Steve, FV80

I see a number of guidelines that need to be established by some kind of SCCA committee, etc.

In your example, do we know for sure that SCCA was involved with the Flagtronic coarse data? Who would this have been and what criteria were they complying with? In this case how far ahead of the flag station goes the display turn on?

Is latency at the amount you are talking really that critical? What is the probable latency of the driver observing a well positioned FT200 display? This system will not prevent ALL yellow flag zone incursion accident, only reduce them.

In your example, do we know if the Flagtronic system was set to display a yellow? Did the flag station have a hand held actuator and had it been triggered?

The utility is there if all the parts of the track management are properly integrated.

Brian

[Steve Davis]

I have no way to determine exactly WHEN the FT flag was triggered by any corner - that's another interesting question. I PRESUME that the incident (George's spin and stop on track @ T5) happened just as WE (3 vees) were passing the T3 station (Donnie, me, Russell. George spun at the T5 station (there is no T4 station.. 3 & 4 are quite close together and in line of site), but T3 had their BACKS to the T5 incident presumably until they heard the noise (my video shows T3 workers all looking back toward T1/2 and T5 had JUST gotten their flag out. SO.. not sure which triggered FT.

On the next lap T3 was 'active FT yellow', and EV was hauling the F6 away .. ON the track, but having seen the waving at T3 I had no trouble avoiding THAT incident, but was a bit caught out when Russell passed me when I slowed (he must have missed the T3 flag) and then climbed Donnie's right rear just in front of me. I dove left (even more) to avoid them when Donnie ran up on Jack (F6) and had to hit the brakes pretty hard. I ended up shooting past him, then had to control my own car as Jack moved left to avoid George (in tow).

It got pretty ugly there for a couple seconds. I was thinking D & R might have crashed hard, but both continued behind me despite the contact.
Steve

[Steve Demeter]

If I understand correctly:

So basically the infrastructure looks at the GPS n every car at all times. Then itt merges that info with where yellow flags are and when a car gets to the yellow flag zone,s display light up?

So there is some significant computer power as well as GPS receivers that "talk" to the individual cars?

Now it makes some sense.

Each "zone" for a yellow needs to somehow be known by the master brains so it can turn the in car displays on and off as they enter and leave the yellow zone, right?

Someone a wholwe lot smarter than me is going to do that!!!!!

[Steve Davis]

If I understand correctly:

So basically the infrastructure looks at the GPS n every car at all times. Then itt merges that info with where yellow flags are and when a car gets to the yellow flag zone,s display light up?

So there is some significant computer power as well as GPS receivers that "talk" to the individual cars?

Now it makes some sense.

Each "zone" for a yellow needs to somehow be known by the master brains so it can turn the in car displays on and off as they enter and leave the yellow zone, right?

Someone a wholwe lot smarter than me is going to do that!!!!!

1). Display is always 'lit up' - shows GREEN when no other flag or action is required. There are 2 or 3 different screens for GREEN.. not sure why - maybe just to help keep you AWARE of the display - lest it fade into the driver's 'background'.
2). Yes.. the GPS receiver does some of that processing and delivers 'somewhat processed' location data to the FT200.
3). Yes.. all of the corner perimeters are set before the event starts. The cars constantly TX their location info. The control computer is advised that X flag is needed at Y corner (on, I think, the SAME comms network - but might be different to reduce data collisions). The control code looks up which cars are at or inside the perimeter grid for the object corner(s) and relays the appropriate command(s) to the appropriate cars.

I'm hardly on the inside as to HOW the computer and comms actually work, but would guess that the main computer constantly keeps track of which cars are inside of which perimeters as they pass through the turns. Then, when a flag is called, it just has to look up WHICH cars are inside that perimeter .. and transmits to those cars... perhaps :-).. I think that's the way I would do it to start with, but they have actual EXPERIENCE and I'm sure have modified code as needed over the years to improve comms and decrease the latency as much as possible.

I should clarify that, I have NO REAL info on just exactly how this all works. I just have some info that told me what kind of chip they are using for comms (thanks to Brian Harding) and a good bit of NON-automotive experience in RF packetized comms, data sharing and code writing. In other words...I'm GUESSING .

Steve, FV80