GPS At Any Speed

[Mellow_Labs] was asked to create a GPS speedometer. It seems simple, but of course, the devil is in the details. You can see the process and the result in the video below.

We have to admit that he does things step-by-step. The first step was to test the GPS module’s interface. Then, he tried computing the speed from it and putting the result on a display. However, testing in the field showed that the display was not suitable for outdoor use.

That prompted another version with an OLED screen. Picking the right components is critical. It struck us that you probably need a fast update rate from the GPS, too, but that doesn’t seem to be a problem.

The other issue is, of course, that you have to have a GPS lock for this to work. Inside the urban canyon, you might be better served with a different method. You might think about an accelerometer, but while that’s easy in theory (velocity is the integration of acceleration), in practice, errors and other issues make that a tough way to do it.

The project wraps up with a nice case and some special display modes. We were sorry that the code and STLs were available “on request,” but you’d probably do it differently anyway. This isn’t the first GPS speedometer we’ve seen. Ever wonder how fast your dog is going?

39 thoughts on “GPS At Any Speed

  1. Just put a magnet on the wheel, and time it with a hall effect sensor. If you know the wheel diameter, you know the speed.

    Had a simple setup like this as a kid, probably was like 20$ or so. Used an lcd screen (old style black and white) so daylight visibility wasn’t a problem. Was able to run off of a coin cell for a couple years.

      1. Ya, I’d be on board, except that this is a YouTube video by someone trying to do the whole “content creator” thing. Within which successes means the project needs to be chosen to have a good, slightly clickbaitly title and thumbnail. Which is how you get GPS as a speed sensor. Generally, GPS sucks for this use, compared to a local solution. Unless you’re in an airplane I guess.

        Projects like this just seem rather… artifical to me. Maybe it’s that I enjoy building projects and doing design work, and try to be fairly pragmatic with my designs. Or maybe it’s that I really don’t care for the psychological games played by modern social media, YouTube very much included.

        I work in computer technology,and I’ve spent a good bit of time thinking about the merits of systems like YouTube (or tictoc or Instagram or whatnot) and I’ve pretty much come to the decision that we’d be better off without them. More specifically, we’d be better off without platdorms designed to be psychologically addictive that lure people into playing their game py promises of fame and money. Or that hide behind claims like enabling better connections between friends or enabling the sharing of information.

        It’s been really sad to see a lot of this community move over to YouTube as a platform; its changed the character of it significantly. I don’t want to blame individual people who are caught in the system, I’d prefer to blame YouTube. But at some point, it’s our responsibility for using it as a system, whether watching or creating.

        1. so much +++

          Two things I recently thought about in regards to YT/Google (fck alphabet):

          1. When complaining about missing source links in replies to comments I sometimes get “but YT/G often deletes comments/replies with links inside them”.
          Now AFAIK this is hard to check – even with ones own comments (can I see all my comments anywhere? a few years back I couldn’t find such an overview).

          This got me thinking – Google does have a “vested” interest in everyone “googeling” instead of just clicking on a direct source link. In fact Google has no interest in you “surfing” the web at all as was quite usual even >15 years ago (I think).
          I hope & think this ^^ is not an actual reason for G to delete replies/comments with links on YT but the conflict of interest is there…

          2. “Plagiarism and You(tube)” – again, G has no internal/inherent interest in keeping content mills from uploading shit – plagiarized or not. They only care about ad-revenue.

          I mean with their own search engine in the back and (enforced) auto subtitles (+ translations) on YT it should be easy to put a link-list of related/similar YT videos and external sources below each video (with a similarity score) and maybe even actively inform “links” with a high enough similarity.

          1. You do know people abuse links in social media, right? YouTube is no different. It’s best just not to invite the bear in, rather that putting out a raging wildfire later.

          2. Links get nuked immediately. YouTube deletes comments seeming at random; maybe you used a trigger word, maybe you mentioned an online shop, maybe YouTube just doesn’t like you. Sometimes you just get shadow banned, switch browsers or accounts and see your comment vanish.

            YouTube actually goes back thru old comments and deletes ones that no longer “make the grade”, whatever that is.

            YouTube will even delete comments from the creator!

            Who the hell knows.

        2. Well, I do like viewing YT videos pertaining to a repair that I am intending to do on my car, or other things.
          But there was that time I was going to replace the charging circuit on an IPhone, only to discover the circuit changed halfway in.

        3. While I agree with you in principle in fact I find YT incredible. I learned how to charge a Mini-split system, I got a step by step on replacing the bulb in my microwave (you have to tear the whole thing apart to get to it), I reference it any time a car or motorcycle problem pops up, etc. Just about any problem I have there’s a video on how to fix it.

          It’s the epitome of just-in-time learning.

          1. There are also videos on ‘how to fix it’ posted by idiot children, complete morons and/or griefers.

            Don’t get too far outside your competence.

          2. Google is now introducing AI video in its search offering.
            The example given is that you make a video of a malfunctioning device and google will tell you what device it is and gives links and info on how to fix it.
            Available in the US only initially.

            Makes me wonder if that will influence YT content makers.

            Makes me also hunker down even more knowing that all video and images are now indexed and analyzed in a thousand ways, and for me that is about a thousand too many.

        4. No disagreement except on GPS as a speedometer. Not perfect anywhere, but very useful on a boat. Even with a highly accurate water speed detector having speed over ground is very useful. And “highly accurate water speed” at reasonable prices isn’t accurate at all. Yes, you mentioned an aircraft, but more common folk have watercraft.

      2. Before the magnet-on-wheel type there were (and still are) magneto-mechanical bicycle speedometers. A sealed gear unit slipped on the the front axle, a flexible cable ran up to the handlebar, and an odometer-speedometer display bolted to the handlebar. The speedometer worked by having a permanent magnet spinning in a metal cup. This induced eddy currents in the metal, in turn generating another magnetic field, trailing and attracted to the permanent magnet. The force between the cup and the magnet was proportional to the speed difference between them. The cup’s rotation was restrained by a spring, so the cup’s angle of rotation was proportional to that force.

    1. Nowadays you can buy a Bluetooth sensor that can be used for cadence or speed for a similar price.

      It has some kind of MPU inside and measures rotations. They you use either a bike computer or a phone with bike computer app.

      It’s nice because it’s wireless and it doesn’t need two parts (like magnet and sensor), you just use rubber band to place it on your wheel hub.

    2. We made an *average* speed sensor by using a reed switch to press the “+” on a calculator. Ride for a minute, then take the number in the calculator and do the maths. I remember thinking that was the awesomest thing back in the 1980s, and it could be done for a couple of dollars at your local Radio Shack or equivalent. A weird mix of instant gratification (you have that new reed switch in your hand immediately) and delayed gratification (you spend the rest of the weekend fooling around with it to try and get it to work reliably) … then you spend the rest of the week at school, daydreaming how to make it display instantaneous speed, like a real speedometer.

      I wonder what an equivalent challenge would be for a kid today?

    3. just some trivia…i don’t know anything about hall effect sensors but most of these devices i’ve used it’s a reed switch. i know because i have occasionally heard the mechanical click. obviously it isn’t loud, but in a quiet room with my head by the wheel, i sometimes use the sound to calibrate the magnet positioning.

  2. Well… Not ANY speed. Saying that makes it sound like you’re trying to bypass the speed and altitude ceilings for civilian GPS, intended to keep people from using it for missile guidance. That would be quite a hack.

      1. I still don’t…

        Nader once claimed the Corvair was ‘unsafe at any speed’. Built his carrier on this lie.
        He was wrong/showboating. His organization quietly admitted it a decade later. Book is still generating money though, no addendum (‘We were wrong, please ignore this book’).

        Also never said a thing about the original VW bug (gia, van, square, thing), which had exactly the same swing arm suspension, but was popular with dirty hippies (Nader’s core support).

        FYI GPS originally had a speed limit hard coded into all consumer firmware. To avoid it being used for missile guidance.

        1. He DID finally get the fed to pass a seatbelt law. The fact is that NO car should ever have been considered safe prior to the advent of seatbelts. They arent perfect, but the proof is in the numerous lives saved. They fact that it took a high-profile activist and a federal law to force the auto industry to do it is proof of the incompetence anc corporate corruption of our government.

          As to “dirty hippies”, your age-old conservative “othering” of an entire generation is utterly offensive and without merit, not being gemaine to the topic at hand.

          Really sad to see here in the HD forum.

          1. Dirty hippies were never a whole generation.
            And they came to their senses nicely once they were past draft age, had two dimes to rub together and discovered cocaine and BMWs.
            Still assholes, but they mostly got over their dumbass politics. Sure the dumbest of the dumb didn’t, but F them.

            It will happen to this generations 5% loud idiot commies too. Just watch.

            Cars _all_ had seatbelts _before_ the law was passed. Nobody forced it. The law was just do nothing lawyers jumping in after, to claim credit. I own a 1960 and 1964.

            Why do you hate freedom?

  3. Proper visibility of those 7-segment displays requires putting a dark tinted lens over it – that way ambient light doesn’t illuminate the unlit segments, and the contrast with the lit segments is massively improved.

    1. GD. That’s embarrassing for you. Points….HaHa! / nelson

      You ‘incorrected’ TFA.

      If I were you, I’d report my own comment. Try to get it removed.

      Admit it. You took ‘Calc for business majors’ aka ‘baby calc’?

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