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Toys Science

Cart Locking System Released as Open Source 323

An anonymous reader writes "You may have noticed that over the past few years it has become increasingly common to find supermarket and large retail store shopping carts equipped with 'boots' designed to lock up if you try to take the cart outside of the store. Now, someone has discovered through some clever analysis the signal used to both lock and unlock carts, and has designed a portable system that locks up all carts within 20 feet of the emitter! They have released the schematics, software, and detailed instructions for assembling the systems on Instructables, an online magazine dedicated to releasing howto's for everything from rat taxidermy to Shopping Cart EMPs under a Creative Commons License."
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Cart Locking System Released as Open Source

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  • by Elsapotk421 ( 1097205 ) on Sunday July 01, 2007 @07:05PM (#19710825)
    a fair amount of mischief about.....or maybe it's just cowboyneal.
  • by WrongSizeGlass ( 838941 ) on Sunday July 01, 2007 @07:05PM (#19710827)
    ... like a lot more fun than an iPhone. Plus it doesn't require a 2 year AT&T commitment ;-)
  • by UbuntuDupe ( 970646 ) * on Sunday July 01, 2007 @07:06PM (#19710829) Journal
    Is it really a good idea to show all pranksters in the world how to lock up a bunch of innocent people's carts in a store?

    I'd much prefer if supermarket pranksters stuck to less annoying pranks, like hiding a speakerphone and ketchup bags in a baby-less baby-holder, having it play "crying" sounds, and then publicly "beating" the "baby" until it "bleeds".
    • by daeg ( 828071 ) on Sunday July 01, 2007 @07:26PM (#19710955)
      I don't know about you, but I prefer real babies for that authentic feel and sound.
    • by Anonymous Coward on Sunday July 01, 2007 @07:47PM (#19711069)

      I'd much prefer if supermarket pranksters stuck to less annoying pranks, like hiding a speakerphone and ketchup bags in a baby-less baby-holder, having it play "crying" sounds, and then publicly "beating" the "baby" until it "bleeds".
      It's all fun and games until some public-minded guy hauls you off the "baby" and beats you to within an inch of your life...

      Reminds me somewhat of this [] quote from

      cag URL tara: When I was in high school, the school board decided that the biology students had to pay for the fetal pigs that were being dissected. After the course was done, my friend Amy demanded that she be allowed to take the pig, since she had paid for it. There was some WTF from the school, but she got her pig. That weekend, she and her brother dressed the pig up in some baby clothes and a blanket, drove down the street and lit a smoke bomb in the car. They were passing a couple walking down the street when Amy leaned out of the car and yelled "Save my baby" and tossed the pig at the couple. They were doing about 50 mph so she missed the couple. The baby/pig hit the sidewalk, skidded along the concrete, shedding parts and limbs before it impacted a mailbox.

      She said she had never seen such a horrified look in her life.
      I mean, yeah, it's funny, and I hate to say that I laughed at it a lot (and still keep doing so whenever I read it), but at the same time I'm thinking that they should have been locked up for doing something that would have been quite the opposite of funny- if not downright traumatic- for the pedestrians.
    • by FirstTimeCaller ( 521493 ) on Sunday July 01, 2007 @08:09PM (#19711207)
      Or turning the boxes of pineapple upside down cake mixes upside down! That will show the man!
  • by __aaclcg7560 ( 824291 ) on Sunday July 01, 2007 @07:09PM (#19710853)
    Why not have all the carts locked up when someone takes a cart outside the zone and have an alarm goes off on the offending cart. That way the perp can be lynched by the shopping mob before the carts unlocked. That should reduce the number of incidents.
  • by ksheff ( 2406 ) on Sunday July 01, 2007 @07:11PM (#19710871) Homepage
    will be of great interest to a certain inhabitant of the Sunnyvale trailer park.
  • we have shopping carts that are all chained insert a one euro coin to remove it and then take the cart back to the cart corral to retrieve your seems to work fairly well here.
    • Re: (Score:3, Funny)

      by QuantumG ( 50515 )
      It works well until inflation kicks in. 10 years from now, kids and the homeless will be returning those carts by the dozen because everyone else couldn't be bothered walking back for a euro.
      • In France, they used to be a ten Franc piece. When the Euro was introduced, it was worth about 6-7 Francs, so there's already been some devaluation. Here in the UK, they use a £1 coin, which is worth just under 1.5.

        The same approximate denomination of coin has been used for about 20 years, and so I don't expect inflation to be a huge issue for a lot longer than ten years, unless Europe catches up with the US in terms of inflation.

        • by QuantumG ( 50515 )
          When I was a kid, they used 20c coins.. no-one returned the trolleys. Us kids used to collect them for pocket money, and the joy of outrunning the fat security guards who would chase us around the underground carpark.

          Now the only few stores that do this use $2 coins and everyone returns them.

          • ...but nobody uses the carts anymore 'cause they couldn't find a $2 coin. Seriously, they exist?
            • by QuantumG ( 50515 )

              Where our $2 coin is smaller than our $1 coin.

              Kinda like how, in the US, your 10c coin is smaller than your 5c coin.

              • Re: (Score:3, Informative)

                Hm. Well, in the US, our 10 and 25 coins used to be silver, with the former proportionately smaller than the latter. There used to be silver 5 coins, but they were impractically small. When the nickel replaced them, for some weird reason, the mint decided to make the coin 5g in mass (none of our other coins are metric), and made of less precious metal, and so we wound up with the current odd relative sizes.

                What's the story with your coins?
      • Re: (Score:2, Insightful)

        by Anonymous Coward
        That already happens (at least here in Ireland, where a euro ain't worth much anymore), and is considered a feature, not a bug. It doesn't really matter _who_ returns the trolley, so long as someone does.

        • by eobanb ( 823187 )
          Isn't a euro the same value basically anywhere?
        • Which is fine until people start making it a full time career. It's no fun to have your trolley disappear the moment you turn your back on it, leaving you with bags to carry and no $2.50 deposit (curse you, AU -> UK exchange rate). This sort of thing works well until it really catches on and then it gets annoying. Then again I never had problems like that in mainland Europe when I was over there so maybe it was just London. :P
    • we have shopping carts that are all chained insert a one euro coin to remove it and then take the cart back to the cart corral to retrieve your seems to work fairly well here.
      So if you don't return it, you bought a shopping trolly for one euro. Sweet! How much is that in American, $50? I hear the exchange rate has been sucking lately.
      • It's just a bit more than a buck (I think 1.33 or something is the rate), but still, you get a farily cheap trolly.

        But let's be serious now. Yes, it's common in some places here that people "drive" their groceries home in the cart, but they usually bring it back, sooner or later. The homeless people that could "profit" from the carts usually won't spend that Euro for something they can fairly easily get for free.

        Maybe it works because people here already brought their carts back before they were "leased". D
    • Re: (Score:3, Insightful)

      by demonlapin ( 527802 )
      That gets people to take it back to a cart corral instead of just dropping it in the parking lot... I think this is more aimed at people who try to steal carts (they're surprisingly expensive).
      • The Aldi stores do it not so much to prevent theft (a person who wants a cart would happily spend a quarter for it.)

        The real reason is to encourage people to return the carts to the corral so that they don't have to employ teenage boys to round them up like all the stores used to.

      • by hendersj ( 720767 ) on Monday July 02, 2007 @12:13AM (#19713151)
        Yep, that's exactly what it's aimed at.

        Used to work for the corporate side of a large food & drug retailer in the US; those shopping carts, wobbly wheels and all, cost on average about $120 each - and that's before the wheel lock systems were put in place (no doubt that has driven the cost up).

        The ironic thing here is that some of the supermarkets have parking spaces outside the lot, but the carts don't roll outside the lots, so sometimes people can't get their shopping back to their cars. On the flip side, I watched one lady try to steal one of these carts - she got about 3/4 of a block away with it, and it was quite a struggle for her. Clearly she hadn't read the signs that said the cart wouldn't work outside the parking lot. It also was clear that what was in the cart wasn't her shopping.

        Loss prevention is big business. This is what happens when people steal from local stores - the stores end up having to put measures in place that inconvenience everyone.
    • by martinX ( 672498 )
      We have that at Aldi stores here (Australia) and it has been tried in others, but they dropped it. Sounds like a good idea, but you try and juggle all the shopping and two little kids, the last thing you are going to do is take the damn trolley back. So you get pissed off that you've been charged a dollar for the privilege of shopping there, so you go to the supermarket that doesn't charge that. You may end up paying more, but you're shopping somewhere that doesn't treat you like a delinquent for not retu
      • If it was 20 cents, I'd gladly leave it in the trolley for enterprising youth to claim

        Australian youth must be really well behaved. 'Enterprising' youth here would rather have some fun and dump it in the canal than return it for a mere 20 eurocent. Of course the lack of canals in Australia might have something to do with it as well.

        • by martinX ( 672498 )
          Well, maybe I'm *hoping* they'd take it back for 20 cents. Chances are the return is too low for the youths old enough to push trolleys around safely, and shopping centres probably don't want 8 year olds pushing them around for pocket change. One flattened kid just isn't worth the hassle.

            Cue the "Back in my day, you could buy ... for 2 cents" speech.
      • When your kids get a bit older, you send them to put the trolley back to get them out of your hair for a bit. They have fun, pocket the $1, and then you go home.
        • tThey have fun, pocket the $1, and then you go home.

          I think you mean "They get run over in the parking lot, die, and you go to jail".
    • If you use 2 coins, 2 trolleys.. flip them facing away from each other on the ground kinda like a reverse 69. This should allow you to get both coins back by putting the chain from one cart into the other.

      If the chain is long enough, you can do this around a lamppost.
      • The chain is tiny, too short for you to couple a cart with itself by one link. The ways trolleys nest makes them just fit.
        • I've done it with Aldi trolleys in the UK that take £1 coins.
        • by Lehk228 ( 705449 )
          side by side, one facting one way one facing the other, the chains should fit that way with the bonus of being obnoxious to move while stuck together like that.

          do this in the middle of the aisle on a busy day for instant lulz
    • Re: (Score:2, Interesting)

      by kryten_nl ( 863119 )
      Like with most highly sophisticated systems, an unfolded paper clip will do fine.
    • Re: (Score:3, Funny)

      by donutz ( 195717 )
      we have shopping carts that are all chained insert a one euro coin to remove it and then take the cart back to the cart corral to retrieve your seems to work fairly well here.

      That would never work here in the one carries one euro coins...
  • by PeeAitchPee ( 712652 ) on Sunday July 01, 2007 @07:12PM (#19710883)
    As if millions of homeless suddenly cried out in terror and were suddenly silenced. ;-)
  • by Anonymous Coward on Sunday July 01, 2007 @07:14PM (#19710891)
    Creative Commons is not Open Source. Creative Commons is not Open Source. Creative Commons is not Open Source.
  • Wacky Race (Score:5, Funny)

    by Joebert ( 946227 ) on Sunday July 01, 2007 @07:37PM (#19711011) Homepage
    This 4th of July when both me & my neighbor get our lazy asses to the grocery store to get cookout supplies at the last minute, I will laugh evily when he flies over the handlebars & lands in his basket when we're both 10 feet away from the last case of beer.
  • by Anonymous Coward on Sunday July 01, 2007 @07:38PM (#19711017)
    Fun with supermarkets and security strips:

    1. If you're in the UK and you've bought region 1 DVDs, look inside the case and you'll most likely find one of those long thin security tags.
    2. Peel off one of those security tags and stick it the underside of a shopping trolley.
    3. Sit back and wait for some unsuspecting shopper to trigger the alarm, when going in nobody will really bat an eyelid, but if they walk out with a trolley load of shopping and it goes off, things will get interesting.
    4. Tag as many shopping trolleys as you can for maximum fun.
    5. ????
    6. Profit!
    • It's much more fun to hide them in the linings of coats of people you don't like :)
      • by poopdeville ( 841677 ) on Sunday July 01, 2007 @08:23PM (#19711295)
        I did that to a friend of mine when I was in college. The library had an alarm system in place so that books couldn't be taken out of the library without checking them out. A friend of mine worked at the library and gave me a bunch of active strips.

        So I carefully unsewed part of my friend's back pack strap, inserted a strip, and sewed it back together. I also threw some strips in random pockets, just so he'd think it might be over once he found them.

        You could always tell when he was leaving the library. The alarm would go off and he'd yell "FUCK! EVERY FUCKING TIME!"

        I also put one in a friend's shoe. He became quite neurotic.
    • 2. Peel off one of those security tags and stick it the underside of a shopping trolley.
      3. Sit back and wait for some unsuspecting shopper to trigger the alarm, when going in nobody will really bat an eyelid, but if they walk out with a trolley load of shopping and it goes off, things will get interesting.

      It is much more fun to stick them on the bottom of your shoe. Make a quick run into the stor to pick up a single small item such as candy. When they find the tag, you have plausable deniability. You mus
  • sigh. (Score:3, Interesting)

    by Anonymous Coward on Sunday July 01, 2007 @07:56PM (#19711135)
    1. nerdy does not imply not-asshole
    2. this was not actually designed by a competent engineer. a competent engineer would have put the transmit coil in an lc circuit tuned to the right frequency and thus made it way more powerful while consuming way less electricity. this is essentially an electric heater that radiates a small magnetic field.
  • I've never seen one of these in use on the west coast of the US. Sounds kind of strange - why shouldn't you be able to take a shopping cart outside? Do you just have to eat all your groceries at the store, or only buy as much as you can carry at one time?
    • Re: (Score:3, Informative)

      by AdmNaismith ( 937672 )
      These systems are used to keep people from taking carts past the store parking lot. Generally there is a painted line indicating how far you can go before the 'boot' will activate.
      I don't understand how I keep seeing K-mart trolleys miles and miles from the nearest K-mart, but it explains the need for the 'boot' system.
    • Re: (Score:3, Informative)

      by nonsequitor ( 893813 )
      They use them at the edge of the parking lots, like an electric fence, to keep homeless people from stealing the carts. It reduces the amount of shopping carts they need to replace each year and saves the store money.
  • by OzPeter ( 195038 ) on Sunday July 01, 2007 @08:06PM (#19711183)
    We didn't need some fancy electronic locking device to stop trolleys leaving the car park (translation to American: carts leaving the parking lot)

    Instead each trolley stacked up in the waiting area had a small mechanical lock that attached a pin to the trolley in front by a chain. In order to release the next trolley in line you had to insert a $1 coin, which was retained in the lock. When you finished using your trolley, you locked it back up again and your coin was returned. No high faluting electronics, a built in incentive to return the trolley, and no mysterious lockups.

    Of course trolley wheels have been designed since day one to lock up without any fancy electronics inside them ..
    • Re: (Score:2, Insightful)

      by Anonymous Coward
      For a dollar, I'll take the $800 cart home, thanks.
      • Me too. Can't be leaving that pile of other peoples' junk that I spent all week collecting round town just lying around out the front.
      • Re: (Score:3, Insightful)

        by chgros ( 690878 )
        For a dollar, I'll take the $800 cart home, thanks.
        And what will you do with it?
        The system is not so much designed to prevent cart theft as it is as an incentive for people to put carts back in their place (not all countries have minimum wages as low as the US so they can't afford to pay people to do that)
    • by Thng ( 457255 )
      I've seen the "deposit" for a cart done in Canada, too. The reason it probably hasn't caught on in the US is that there is no widely circulated dollar coin. The Sakakawea dollar hardly counts.
    • I have seen those in the US, primarily in airports where you can "rent" a stroller or cart and then return it for the majority of your deposit back.

      As for a supermarket... that would be so incredibly inconvinient that I would never shop there. I rarely have $1 bills on me, let alone a $1 coin. If I could quickly swipe my credit card, that would be a little better.

      But it also means you have to walk the cart back to a station to get your deposit back. Not exactly convinience.
    • by houghi ( 78078 ) on Monday July 02, 2007 @01:34AM (#19713633)
      The same is done in most (all?) European countries. You even get keyhangers specialy designed to act like a coin, so you do not need your change.

      I went to a store and needed change, instead they gave me two plastic coins I can use. I leave them in my car and use them whenever I go shopping.

      One disadvantage: after the introduction of the Euro, it is not very clear what coin to use. It varies between 50cent, 1 and 2 EUR coins. Sometimes all three, other stores just one.

      I rarely see carts. Apparently people are more interested in the little money then in the cart itself. I also see not many homeless people, so the demand for carts is a bit lower perhaps then in the states.
  • by Opportunist ( 166417 ) on Sunday July 01, 2007 @08:08PM (#19711201)
    ...a new gadget for sale at ThinkGeek in the forseeable future? :)
  • From a quick scan of the site, it looks like ths is the most intelligent thing on the entire place. Other projects include "Boobs in a Box," and a straight hookup of a piezo-electric buzzer called "The Headache Machine" with some retard commenting in bad English that it seems "really hard to make."
  • by iamnafets ( 828439 ) on Sunday July 01, 2007 @08:42PM (#19711429) Homepage
    I think a better target would be the vibrating coasters that signal "your table is ready". If you could somehow set up all of those to go off at the same time on a Friday night you might...have them all going off at the same time on a Friday night! Drive-by mayhem!
  • Charming (Score:5, Insightful)

    by Le Marteau ( 206396 ) on Sunday July 01, 2007 @09:04PM (#19711539) Journal
    Senseless vandalism. Swell. How laudable. Life is tough enough, but how about locking up some wage-earner's cart, after he has suffered under the hands of a sadistic boss, just wanting to get some grub and go home. Delightful.
  • can the cost of putting a remote control boot, sensors, transmitters etc. really cheaper than losing some carts?

    • by VidEdit ( 703021 ) on Sunday July 01, 2007 @09:48PM (#19711951)
      "can the cost of putting a remote control boot, sensors, transmitters etc. really cheaper than losing some carts?" Obviously, yes, that is why stores pay big bucks for these systems. Remember, they don't just lose a few carts, they lose all of them one at a time. They have to hire people to cruz neighborhoods looking for them and bring them back. Those they do find are often worse for the wear. Ones they don't find wind up rusting in creeks and abandoned, broken in alleys and fallow yards. Locking shopping carts help prevent neighborhoods from being littered with these abandoned carts brought home on one-way trips by people who can't be bothered to buy a "granny cart." The addition of locks to my local shopping center's carts has quickly eliminated those carts from being strewn about by people walking home with groceries. The newer systems are much better than earlier iterations that use purely mechanical devices triggered by small "speed bump" like berms which rimmed the parking lot. These new systems are more reliable and have fewer false triggers--well, until now :-) Note, I support walking to the store but I don't support stealing the cart just because it is convenient to push home--and no, most of those people pushing carts home are not fragile elderly people, at least not in my area, so that isn't the issue. And no, nobody ever takes them back, either. If they did, it wouldn't be as big a deal.
  • The majority of the links on the site (pictures, etc.) are now coming up "Unavailable" or 404 errors. It's lying to us... apparently it doesn't know how to say "I can't take it anymore!!!"
  • Aldi's uses a "deposit" with their carts, you put a quarter in to unlock it from the rack and get the quarter back when you return the cart. The parking lots I have seen are always clear of carts, it seems like a cost effective way to manage them, its a simple mechanical lock.

    I guess something like this would be needed in area's where homeless take carts on regular basis but then arent we just treating side effects rather than addressing the actual problem?
  • by lena_10326 ( 1100441 ) on Sunday July 01, 2007 @10:33PM (#19712319) Homepage
    Why didn't they just build the device to always lock when there's no signal? A transmitter in the store emits a continuous signal that keeps the wheels unlocked. When you take it out of the parking lot and go out of signal range, the wheels lock up.

    Seems a bit more prank proof that way.
  • an UN-locker, so that when I'm parked at the edge of the damned lot and the cart freezes up 20' from said edge where transmitter is, I don't have to shuttle the bags from the stuck cart to my car while blocking traffic and having a cart that I can't reasonably get back into a cart-pen?

    Just a thought. I HATE these things.
  • The carts are part of the culture.

    The system is grossly skewed towards the interest of the cart-owners, who abuse their control over the implements.

    We have the right to take the carts away for our convenience (fair use) — and it is not "stealing", because we always plan to bring them back some day. It is stupid and unethical for the supermarkets to fight their customers over this, especially the single mothers (who have never gone shopping) among them.

    SMAA (SuperMarket Association of America) and similar oppressive institutions world-wide will, no doubt, try to suppress this new invention, so all freedom-fighters must start mirroring the just released information on their computers.

  • by drspliff ( 652992 ) on Monday July 02, 2007 @08:47AM (#19715933)
    The ASDA brand of super markets (Walmart owned) has had these for ages at the end of the walkways & store carparks.

    It's amazing how many older people I've seen caught out by this because they need assistance to get their shopping to their car or to the bus. A few times I've seen ASDA attendants dragging the locked trolley for them instead of waiting 5 minutes to get somewbody out to unlock it.

    In theory it works, in practice people just carry the trolley over fences to stop it being locked up while people with disabilities or frail people end up being given a hard time.

    It's like DRM but for shopping trolleys :D

All laws are simulations of reality. -- John C. Lilly