GPS Map is not accurate

[USFracing]

Hello everyone,

Well, I have encounter this problem several times usually once or twice during every testing session but this Thursday it happened 1 out of every 2 runs. The track is open and clear of trees. The GPS antenna is mounted on top of the roll hoop in an open wheel car, and the DL1 is mounted level with velcro. Any insight on this problem is much appreciated.

Here are some images of the problem:


I understand that the map is off the track but one of the laps is way off to the other laps, as it looks like the driver cut through the grass in 3 turns.


This is my concern, the GPS shows me a line way off and presents misinformation




Thanks for the help

[tristancliffe]

It looks to me as though the logging rate of either (or both) accelerometer or GPS data is too low, as well as having problems with the reciever signal. Noise in the wiring? Dodgy connector? Vibrations?
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Monoposto 2000 - Reynard 883 Toyota

[faraday]

These observations are like mine from some go kart testing. The F-SAE car and the circuit pictured present the same difficult scenario of a small lively vehicle performing tight manouvres. Tristan's noise and receiver signal sugestions are at least close to the cause, but I suspect that the source is mechanical rather than electrical.
Improving the mounting of the DL1s (we tried several) in the kart improved mapping performance, but only up to the standard pictured here. More work was required and not difficult to apply, but equipment failure, probably due to the harsh conditions, intervened.
There were telltale signs in the data that vibration was severe. It was visibly present in the structure, but to what extent the jerky motion of the kart itself was forcing it was uncertain. A single cylinder engine could contribute too. What is your engine configuration?
Both accelerometer and GPS module elements were affected in my experience.

I am keen to see some of your RUN files to look for deeper similarities. Email to rotoflow at optusnet dot com dot au if you desire.

[osvaldo]

I think i might have the same problem the mapping is inaccurate and the speed keeps getting higher[/img]

[shanba]

I use a DL1 in a Formula Ford, and it took several tries until I found a happy spot for the GPS antenna. I had it on the roll hoop at one time and had similar results as you. I currently velcro the antenna to the bodywork, with some tape over it for precaution. This has given me good consistent data. I suspect its vibration related, and mounting it one layer removed from the frame probably reduces the vibration on it. I also velcro the main unit to a plate that is attached to the frame. Good luck.
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Scott