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Thread: Best way to import GPS track for point mass simulation?

  1. #11
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    Off Track Betting

    Am I missing something ? A race track has finite width lanes for which you shoehorn the car thru a racing line path. This 'line' will be different for each of vehicle and tire parameter settings.

    To be specific, is the data being shown here == 'THE LINE' or is it just a walk around the center of the track map ?

    BTW: with a little handle graphics you can study the track mapping problems a bit better. I'd use radius because it relates to my sense of surveying, but here is curvature to be PC.
    I needed a crutch to figure out where I was on the track.

    track_curve.JPG

  2. #12
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    Recommended Lapidary Method Discussion

    Here is an excellent paper by Honda on the subject of Lap Time Simulation. (Speaking of which by the O.P.) Go 4 it. Log-in to download and study.

    https://www.hondarandd.jp/point.php?pid=1264&lang=en

    Honda Lap Time Sim Abstract.jpg

  3. #13
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    Recommended Lapidary Method Discussion

    Here is an excellent paper by Honda on the subject of Lap Time Simulation. (Speaking of which by the O.P.) Go 4 it. Log-in to download and study.

    https://www.hondarandd.jp/point.php?pid=1264&lang=en

    Attachment 1283

  4. #14
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    Quote Originally Posted by rory.gover View Post
    Nb. the output of a GPS signal is lat & long plus noise, which can be converted to relative x & y coords plus noise without adding in additional noise. In order to calculate curvature, you need the single and double derivatives of x & y wrt arc length. Differentiating noisy signals is generally Bad News Bears.

    In general, it's best to filter raw signals and then apply math to it as necessary, rather than applying math and then filtering (advice given with all relative caveats and exceptions, particularly related to statistical smooshing - i.e. Kalman filters).
    Agreed. If you are going with a filtering method (rather than the above curve-fit to arc methods), working with the raw signal is often preferential. Not sure what GPS noise looks like, but it's likely possible to remove. I'd at least recommend trying to remove some before the differentiation and taking a second pass at the final data only if necessary. I work in the image processing world (laser diagnostics) and most of our filtering is to reduce dark noise, Gaussian noise, etc. which can often be done relatively easily before doing heavy math on the data.
    Jim
    "Old guy #1" at UCONN Racing

  5. #15
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    IT'S AN OUTRAGE!
    ==============
    Quote Originally Posted by BillCobb View Post
    Just 2 of many options.
    Bill,

    I am very disappointed in your Northern Hemispheric imperialist attitude shown above!

    And shame on all you 'Strayan students for being so slow to protest this outrage!
    ~o0o~

    What is the old-fart going on about?

    Well, Bill has drawn the Calder Park track-map from a viewpoint somewhere around the North Pole. Or more likely from his secret underground bunker, somewhere under North Merca. Namely, from deep underground, looking UP at the track.

    Geez, what will this do to the laptimes???

    I suspect the first few cars will be very slow, given the very long tunnel they will have to dig under the bitumen. Then there is the inverted gravitational field to contend with. And perhaps even negative laptimes ... but will that be good or bad for points? On the upside, driving underground might mean no problems hitting the cones, err...???

    Aarghhh, all this standing on my head trying to figure this out is hurting my brain!
    ~o0o~

    Tim,

    Bill got it right in a later post where he questioned why you want to follow "the line" that was set by a vehicle probably a lot longer and wider than the average FSAE car. And travelling much slower.

    Methinks that all you really need is the positions of the cones. The track-map (right-way-up, of course!), together with some of the abundant video footage available, should allow you to reasonably accurately determine those cone positions.

    Then on to the whole business of writing a HALF-DECENT VD-simulator. "Point-mass" is oh-so last century...

    Z

  6. #16
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    InFarted Track Map

    Z: It was the only way I could get you to bite on the total concept at hand from an unblemished, unMatlabed and unOptimumed podium. No need for gpxread, just a couple of moving median filters. Who cares what the track is. Can they address the real problem(s) using Excel ? Or in your case Visual Basic.

    I have a few other cone deliniated tracks that have been a challenge. Just what do the children say about this one ?track1.JPG

  7. #17
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    Quote Originally Posted by BillCobb View Post

    Just what do the children say about this one ?
    Hmmm? Well, that latest track-map looks almost exactly like the previous two, just with the filtering cranked up a few more notches. In fact, just a smidge more smoothing and laptime simulation will be a doddle. Pure Ay all the way around. This FSAE laptime optimisation is getting easier each day!

    (Tim, I hope you are paying attention...)

    Z

  8. #18
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    Track Race

    Just to clarify: THIS is a racetrack. Notice the steel and concrete retainers ? The best path thru this maize is the science project, not like a single tracktrace_track.JPG copied from a golf cart going 6 - 7 kph down the road.

  9. #19
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    It's possible to draw a reasonable racing line automatically. See RCVD p.341 (bottom of the page). The "best" line varies with the vehicle capability...

    Going back to Bill's oval, "Just what do the children say about this one ?"
    On my screen (aspect ratio) it looks like a circle will fit within the edges of the track, leaving just enough for the half-track-width of the car.
    Last edited by DougMilliken; 01-12-2018 at 01:05 PM. Reason: added second paragraph

  10. #20
    Bill,
    Thought that track looked familiar!! It's the current Silverstone F1 track

    Michael.

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