Can anyone tell me what might be happening here?

[Maxx]

Hi,

I've posted elsewhere on various GPS anomolies (in the GPS Specific section) and have received good answers (esp from Al, thanks Al). I think these have pretty much answered my questions, still getting "cuts"/"dropouts" occasionally but still pursuing that one.

This however is a new one on me. Data was captured at Rockingham UK, GPS was flat with pretty much 360 vision. As the surface was GRP I had to tape it down but only taped the sides, not the top.

I did 2 runs, the "screwy" one is the first, the 2nd run was faultless, not even cuts/dropouts. Nothing changed between the 2 runs in terms of positioning etc.

The first pic is what I get when I load the data in. I've looked at it in detail and with lap markers etc. I generally get about half way through the run then, coming along the bottom straight (left to right) the line starts to change (the lower line) and it continues (i.e. using playback data pointer still moves forward BUT on what looks like a "loosening" line. If you follow the line in relation to the circuit map, it sort of goes in the right direction but looser.



This is most odd? Any ideas? is there anything I can check (the run data is shown below, looks OK?). Anything I can try? Anyone want to look at the data?



TIA

Malcolm

[Patrick911]

Hi Maxx,

I had something similar few months ago. The GPS signal wasn't good I have to admit. But the result I had was quite similar to your one. Then in => Data => Analysis Options I removed the cross at "Trust accelerometer data over GPS data" . Then the track map was not that precise but it was correct and showed the lines where I was driving.

Don't know if that can help you, just wanted to mention it because the problem is quite similar.
Best regards Patrick

[Maxx]

Patrick,

Many thanks for your reply. After responses on the forum here I now always only have the first item ticked on Analysis Options, which is what gives me the above.

If I have ticks in 1+2 I get a correct looking trackmap but only 3 laps shown in lap & sector times and, if I PLAY the session it stop after 3.5 laps, the car "marker" freezes but still shows G movement. It stays like this for about 180 secs of driving.

If I have ticks in 1+2+3 I get the same thing.

If I have ticks in 1+3 I get an even worse example of my initial problem (see below)



This was a very limited run where I would really like to see the data, anyone any idea whats happening and if I can rescue the missing laps?

TIA

Malcolm

[nikpro]

I also had a very similar experience to this at Oulton Park. The GPS sensor was fitted to a fiberglass Lotus Elise and sometimes gave perfect results and sometimes didn't. The funny thing was I had a lot of problems with sensative electronic equipment on the day and I think there was some cars running without radio supression - I wonder if this is what causes the erratic GPS traces?

[Maxx]

Fraser,

Thanks for the reply. This was on an Elise also. No problem with other traffic though as I had the whole circuit to myself (Rockingham National).

The other odd thing I have found out since is the speed continues to be shown BUT is higher than it actually is. I exported to CSV and merged it with the video (via TRackvision). You end up with video with telemetry overlay. You see the car continue on the normal line but the trackmap/trace goes all screwy, you also see much higher speeds (est aboout 20mph+) also, when stationary in the pits it shows as 16mph. I'll post a couple of screenshots.

Malcolm

[Maxx]

Here are some screengrabs of the video mentioned above.

Here is a section of the lap when the logging was working correctly, speed is 80mph.

<CLICK IMAGE FOR LARGER VIEW>

Here is the same section after the logging had gone screwy, note the speed is now 98mph.

<CLICK IMAGE FOR LARGER VIEW>

At the end of the session the car is stationary in the pits and still shows a speed reading.

<CLICK IMAGE FOR LARGER VIEW>

I would like to hear from someone at RT on this if possible. I had special dispensation to do 10mins on circuit and with the car for a deal I was working on. As it happened I got to do a 2nd session as I had a couple of other issues, luckilly I did as I had very little proper data from run 1.

Malcolm

[RTUSA]

Malcolm:

I'm reasonably sure that this is the result of a longish GPS droput. I can tell for sure from the data. Can you please zip the .run (not .raf) file and email to aseim@race-technology.com?

Thanks,

[Maxx]

Al,

Thanks, zip file sent.

Malcolm

[nikpro]

Malcolm,

Where are you mounting the unit in the elise?

We are using an AX-22 and when screen mounted we got perfect data, when we velcroed the unit to the passenger floor the data was not so good.

Also where are you mounting the GPS antenna?

I know none of this helps but would be interested to compare -are you interested in seeing the Data from the BLiNK Motorsport Elise (Honda Powered)?

[Maxx]

Fraser,

This was just a quick one-off with no time to test first. I mounted the DL1 unit on the passenger side "sill" and the GPS on the boot, about half way down (S2 Elise). I did 2 x 10 min runs and the 2nd one worked perfectly.

I actually did one sesion a while ago with the DL1 taped to the passenger floor and had problems with this. I think I posted something about it here as it was not "just" a DL1 mounting thing, it was software related (I upgraded to latest 6.3.100 from here and OK now). That time the GPS was mounted on the "roll bar" but as this is not totally flat and I did get the odd dropout I changed it on this run.

I'd very much like to see the data from the BlinK machine and will gladly swap data. I may well have quite a bit of Elise stuff coming up as I work for LoT (instructor) and it's something I offer occasionally on coaching sessions. My Email is visible here.

Malcolm

[nikpro]

Malcolm - hopefully you have received the files?

Fraser

[Maxx]

Fraser,

Yes thanks. If I get a minute later i'll send you those Rockingham .RUN file, if not,d ef by Tuesday (away tomorrow).

Malcolm