Impossible lateral acceleration data

[MrBlah]

I'm exporting to vbo and comparing to some of my peers to see where I need to improve and I saw some strange data on the lateral acceleration

Pretty sure my car cannot do 5 G on turn one at vir

Every lap looks the same too? !? I thought maybe my mount was the problem but it's the same every lap

The blue line on this first image is mine, the red line is my peer with a very similar car, recorded with trackaddict



as you can see here, every lap with HLT shows the same spikes

[MrBlah]

also looking at the raw csv file the lateralg column does not show these high numbers, max was -1.27 and +1.1

[Harry]

Circuit Tools always calculates acceleration based on GPS. Data exported by LapTimer is ignored. Depending on the accuracy and characteristics of your GPS (compared to RaceLogic sensors), you can get wrong values.

Harry

[MrBlah]

well that's disappointing I'm using a racecapture pro mk2 feeding 25hz gps into harry's laptimer and exporting the vbo file to circuit tools

the other car was using an android built in gps and exporting from trackaddict android app, this setup did not have the strange results

it's very strange that only one axis is bad from harry's laptimer

[Harry]

It is a lot easier to calculate acceleration from a 1 Hz GPS compared to 25 Hz. With 25 Hz the distance between consequitive positions is very small and you get a lot of noise when deriving acceleration from GPS positions. That's the reason LapTimer has a smoothing option when calculating acceleration from GPS (Lap List ‣ any lap ‣ Data Recordings / Recalculate ‣ Acceleration). While smoothing is not required for 1 Hz, it is definitively for 25 Hz. What you are actually expecting is compatibility between ASL GPS characteristic and those of RaceLogic. I doubt you will get a lot of support here. While LapTimer is just sitting in the middle and passing things through, you are probably better off using the GrandPrix edition on an iPad. Big screen and more analytic options than CT.

- Harry

[MrBlah]

I use grandprix with a nexus tablet but if I cant compare to someone else it's not terribly useful

I've not played in the graph screens much, but CT makes it soooo easy to load up a previous sessions data (or a competitor), grab previous best lap and compare to the session I just did

[Harry]

You can load another person's recordings in LapTimer too. Either import a .hlptrl file to add this to LapTimer's data set, or load a Challenge from a competitor. It is sooo easy. But frankly, I can only show the options. In case you are so happy with CT, use it.

- Harry

[MrBlah]

real world example, this guys mini is 3 seconds faster than me at VIR, but half of that is because he's got a lot more power on the first photo above you can see how his speed pulls away even if we apex at the same speed. I also carry more speed in some of the corners, the biggest difference is he's crazy fast up the esses

I would not know this without having CT to compare

[Harry]

Let the guy export his lap or upload it as a challenge. Load it into LapTimer and make it the Reference lap (usually it will be the reference already). Goto Data Analytics of your slower lap and have a look into the Speed diagram and the blue aggregated time won/lost. Check the Train the Trainer document (www.gps-laptimer.de/documentation) on how to interpret it.

- Harry

[MrBlah]

They all use track addict or the dedicated hardware solutions