Control shopping cart wheels with your phone (2021)
begaydocrime.com
Original DEF CON 29 (2021) talk: https://www.youtube.com/watch?v=fBICDODmCPI
begaydocrime.com
Losing a cart is expensive, but it doesn't seem to happen at the scale that would make a full blown locking wheel solution cost effective.
It was completely counterproductive, too. The edge of the zone was about 50% of the way home. Out of spite, we'd push the cart up to the edge, and leave it stranded there, carrying everything the last 200m ourselves.
Not proud of that in retrospect; it goes to show that you can't stop assholes with technology.
It's more also common in places where people walk, since it can be hard to bring groceries home on public transport.
So yes, very localized.
The shop near me doesn't have locking wheels (they used to, but stopped), instead they have a guy in a pickup that drives around occasionally, searching for carts.
Locally all supermarkets actually have locks at the entrace so that people can lock their shopping trolleys next to the cashiers.
Curbs have onramps. Pretty much every corner and every driveway provides a ramp where wheeled vehicles can easily get on to the sidewalk. You will never have any difficulty pushing a shopping cart onto a sidewalk.
https://sdotblog.seattle.gov/wp-content/uploads/sites/10/202...
While things are improving in europe, many sidewalks still have a tiny step. Not high enough to be a problem for someone in a wheelchair but definitely for a loaded cart with shitty plastic wheels. Also it is not uncommon to have people parking where they shouldn't so you can't rely on it. In many part of the world people living in a wheelchair tend to spend a significant amount of time in the street instead of the sidewalk because of "stuff" that block their way on a regular basis.
It was signed into law in on July 26, 1990 by President George H.W. Bush. I hope you get to see a progressive man like George H.W. Bush in the White House again.
https://en.wikipedia.org/wiki/Americans_with_Disabilities_Ac...
The ADA is not a good thing. It's best known recently for forcing UC Berkeley to take down the lectures they used to provide over the internet for free. But it's been having very negative effects since it was enacted.
Page 4, for your reference: https://archive.ada.gov/briefs/uc_berkley_lof.pdf
My favorite part of the system in larger stores is that to handle people not carrying cash (Sweden is pretty long-gone in this regard), you can usually go inside the store to get a free plastic token that fits the reader.
That always made me chuckle, since the entire point of the system is that you're supposed to be incentivized to return the cart to get your money back, so by replacing your money with a free plastic token that they hand out from a basket, they did .. something to the overall system design.
Still fun as an example of how the customer's overall experience is more important than the point of an entire security system, I think.
I always kinda doubted that part, or at least its effectiveness. Iirc a 50 eurocent coin will unlock most trolleys, which is pretty cheap for a whole ass trolley.
And sure enough, there's a lot of elderly people that just have a shopping trolley in their yard or something. This morning I found one randomly in our bike shed.
I’d never seen that in the uk - but maybe that town was the sweet spot in size where it was small enough that you could actually get home with a trolley (and it was nice and flat), and maybe the number of visitors passing through meant rules got broken more - though the trolleys were more in the suburban areas than just where the hostels were.
It's not an incentive to "not steal the trolley", it's an incentive to put it back in its place for people who were already not planning on stealing one.
This way the store and the customers don't have to deal with trolleys strewn around everywhere and blocking parking spaces, among other advantages.
I think when they removed the coins during Covid they just noticed that most people were already well-behaved enough to return the carts to their places, so the incentive is just not needed anymore. Actually in Belgium, Colruyt had never had coins for their carts and it just works.
There's no particular need to change this, because one person can only use so many shopping carts. If you maintain the price at "free", demand saturates and people stop stealing carts.
It's common for people to return carts to a designated area, and it's also not rare for people to just leave the carts somewhere convenient for them. Store employees periodically go around and move the carts back to the place where you expect to pick them up.
Costco is an interesting hybrid case. They make it easy to return the carts "correctly" by providing little depots scattered throughout their enormous parking lot. Realistically, the parking lot is so large that very few people would be willing to return a cart to the front of the store, where you get the cart from if you're going shopping.
However, people also aren't going to pick up carts from those depots deep within the parking lot and wheel them over to the store. So Costco employees still have to make rounds of the parking lot and move carts that have been left there to their correct location at the front of the store. But for Costco, you're supposed to leave the cart in the parking lot, but only in certain locations.
> If you maintain the price at "free", demand saturates and people stop stealing carts.
If the price is $1, the same people who'll steal them will keep stealing them (with a screwdriver it's easy to pry your coin back out of the slot anyway).
> it's also not rare for people to just leave the carts somewhere convenient for them
With the coin, guess what... it will be rarer, because the people have incentive to get their coin back. At least in theory. And if someone doesn't care about their change, some enterprising kids might return the carts anyway to gain some money, and the end result for the supermarket is the same: carts at their designated return locations. The worker just has to go to 3 or 4 of these locations instead of running up and down the parking lot collecting all the stray carts.
It’s compounded because they’re also the only store near me that doesn’t have handbaskets, so you need to either grab a cart or hope there’s a loose cardboard box in the store (which there often is because they expect customers to use them, but you may not find it quickly).
It’s also an incentive for anyone else.
If I put the coin in and then leave the cart in the lot anyways, someone who wanders by is also incentivized to grab it and put it back, as they would get a free coin.
The system is actually somewhat elegant, if you return the cart you pay nothing and if you don’t you pay a small fine to whoever does.
The coins are so that people put them back in their designated storage area, not to prevent theft. A significant fraction of the population are lazy asshole who tend to leave carts next to where their car was parked instead of walking the 10-20 meters it take to return them.
Every single person that doesn't return their cart does so out of laziness. Besides just being an asshole, the cart will take a potential parking spot that someone else later needs to move to free up, and worst of all the wind could blow the cart into someone elses car.
Nobody is gonna kidnap her kids as she walks the cart back in less than a minute. It is simply her being a lazy asshole.
I can see that this is a very personal issue for you, so I'll just say this: People are complicated, and I would encourage you to have more grace for them. If it bothers you that much to see a cart left by a mom struggling with kids, you might consider offering to return it on her behalf.
Most 2-3y old kids can walk and when my babies where too small to walk I would just put my groceries in the bottom part of the stroller and in an hiking backpack instead of a cart.
I get that you don't want to make accommodations for people but you might want to think about what leads you all to get so bent out of shape on this one. At the end of the day your argument boils down to "your spouse just needs to work harder so I'm not inconvenienced by the cart she hung off the curb next to the space I wanted." Society is full of people with differing abilities in differing mental spaces and not everyone owns equipment like that and is willing to spend 10 minutes getting it out and setting it up in a busy parking lot while also wrangling their willful, very curious child.
There are absolutely lazy people, but it's not always the case.
People having newborns typically use baby carriers and strollers and when using the later use the storage space of the stroller to carry a significant amount of groceries. Nobody with a sane mind woud grab 2 newborns in the same arm and throw them in an unsafe shopping cart.
Why would I buy something I really don't want to lose to replace something I kinda don't want to lose?
It usually takes more time to go inside the store, find an employee who is available to get that plastic chip, go back outside to pick your cart and back to the store than it is to just return the cart so you can get your coin/chip back.
The point is not to stop theft, it is just to incentivize people to put back the cart where it belongs instead of leaving it in the middle of the parking lot.
Anyways, personally, I 3D printed a fake chip that can be removed without reattaching the cart and have it on my keychain. I find it more convenient, and hacking the system is fun. I return the cart anyways.
[0] https://www.amazon.de/Caianwin-Shopping-Trolley-Stainless-Re...
A grocery store at Bayview Village, an upscale mall in Toronto, uses this system to stop cart travel outside the grocery store parking garage. Mall management considers carts trashy and that they otherwise bring down the appearance of the mall. This was one of the conditions when the store opened in 2005. Their cart policy may have changed 20 years since.
These carts have, for the last couple years (I don't remember when, exactly), the locks on the front left wheel. It can't be to "disable the carts if someone tries to take them out of the parking lot". That isn't an issue. Though I have not seen it in action, I suspect that if I tried to take a cart through the exit without somehow moving it past whatever device deactivates the lock would have the cart lock up and start skidding (though with the lock being on the front, anyone should be able to just pop a wheely with their body weight and keep on trucking).
That said, I don't claim that these are effective at loss-prevention, but sometimes those jackasses get crazy ideas in their heads and won't be dissuaded by common sense and reality and all those other naive things.
The usual USian aspect of schlepping a shopping cart waay out to your car and then not wanting to schlep it back or to one of those bays is thus far less relevant.
Also, buying all groceries for the next week is rare here. In other words, you just pack your stuff in bags and walk off, no need to bring the shopping cart.
It's a somewhat unique situation (in NL it is not legal to have a store open to the general public except in a commercial zone, i.e. a supermarket cannot open its business in an industrial zone which means the stores kinda have to be in the middle of population centers, which then opens the door to just buying what you need every day. This then in turn means you can go by bicycle and you don't need a massive freezer either).
Interesting how such a relatively innocuous butterfly flap (the zoning laws) result in such an utter change in culture (bicycle, urbanisation, shop-for-the-day instead of for-the-week, etc).
Not just for the whole day, I ofter make a trip in the morning for breakfast/lunch and another in the evening to get whatever I need for dinner.
Most supermarkets in Belgium use a coin but some supermarkets (notably Colruyt) lock their shopping cart wheels.
Supermarkets that have a step-less escalator (e.g. to go to the parking lot in the basement) also use these locking wheels to make sure the cart never moves on the escalator. I live near an Albert Heijn that has these.
we have a Jumbo near here that is below a parking garage and they have something similar, but it's an entirely passive system. The sloped movable walkway to the parking garage floor has this grooved pattern in it's surface anyway (so you don't slip) and the wheels have a similar pattern so they just sink into the grooves on the walkway. There's a brake pad next to each wheel just above the floor and as the wheel sinks into the grooves the brake pad touches the walkway locking it in place. At the beginning/end of the walkway there are these sloped protrusion into the grooves on the walkway that lift the cart out of the grooves as it reaches the end. No fancy locking system needed.
I went through the main gate but left without going through the cash registers. I guess it detected it and thought I was stealing.
In the United States, this is for shoplifting (can you call it shoplifting if they're sprinting to the door pushing a full cart?). If the cart doesn't pass through a checkout lane, the wheel becomes disabled. The local grocery chain here has them, and it's never been deposit-for-a-cart.
I honestly do not know if the shoplifting thing was ever a real problem, or just an imaginary one that they paid a bunch of money to "solve". Occasionally, there are a few carts in the corral where the wheel in question will not roll anymore, and you have to take a new one.
I’ve always assumed it is to prevent literally stealing the carts themselves moreso than shoplifters trying to shoplift entire cartloads of stuff.
In my view it's quite an inconvenience: who carries quarters around anymore? I rarely have any cash with me, let alone loose change.
I expect we'll soon see something where you make a small payment with your card or mobile pay app which is rebated when you return the cart.
As a kid, I almost missed a flight while hunting luggage carts at the airport.
This. Soda bottle deposits when I was a kid.
(Heck, even now. Who am I kidding? My state doesn't have them anymore, but I still vacation in places that do, and I still keep an eye out for bottles and cans.)
I'm sure they don't make much, but it's more than zero.
https://gothamist.com/arts-entertainment/subway-token-suckin...
(Alternate link: https://archive.is/dyeND)
* I think I remember reading about this on hn but I can't find the thread, sorry.
That's what incentivizes you to take your quarter back. I keep a quarter in my car's center console for Aldi and getting a new one is a hassle.
I suspect that if you are going to be shopping at Aldi, you're planning on shopping there and it's not a random one-off, so you already know about the quarters and bring one with you.
Aldi is nice for quick stops because they aren't that big, they have most of what you might want but it doesn't take 30 minutes to get through the store like Kroger.
I try to keep a quarter in the car, but it often ends up in my pocket after I return the cart and I forget about it. I should drill a hole in one and put it on my keychain. But it won't be too long before we don't carry keys anymore either.
My car has an Aldi Quarter stashed inside that my family knows never to spend. It is only for Aldi shopping carts. I joked with my kids once that my Aldi quarter was older than them and that I've used the same quarter for the shopping carts since before they were born. They called my bluff at the checkout of course.
Later, my girlfriend told me that the specialty foreign foods store near the Big Lots she worked at in a different Detroit suburb would intentionally come steal the Big Lots carts, rather than pay for their own (see above, expensive), so the Big Lots clerks would occasionally get sent on a mission with a moving van to get a bunch of their carts from the next shopping center over's parking lot. I think they might not have ever paid for the geolocking wheels, since Big Lots is low margin and those options are pretty expensive, but you can see the incentive to do so.
* In a high-trust high social cohesion culture, you can rely on people returning carts all the way to where they belong instead of just selfishly leaving them in the parking lot once they are done with it.
* In the US, the opioid epidemic means there are many more homeless drug addicts. Stolen shopping carts are useful for them to move their stuff around.
But this is such a cool talk. My local Giant (grocery store) has a wire that goes along the left side of their parking lot. Only about 20 spots there but once you cross that line, the wheel locks. It took me 2-3 trips of confusion why the cart was breaking before a store employee shouted at me "you're gonna lock it" right as I crossed the line. He came out to me, unlocked it and we had a long talk about how it all works.
Argentinian fans during Qatar's FIFA World Cup 2022 using a shopping cart as a barbequeue grill.
A friend of mine had stolen one with his brothers back when we were in primary school. But stores here simply have a guard on their parking lots to prevent people from taking the carts away - haven't seen any tech for that.
I've lived in the US as well and have never seen them there, but it's a big country.
Reminds me of the LoLRa project from cnlohr that transmits LoRa without a radio transceiver.
[0]: https://www.reddit.com/r/neocities/comments/1i7di1c/help_fak...
You have to be about 6 inches away for it two work. There are two locks that operate in tandem but sometimes you have to play the tone for both. Also the property line is in the middle of a lane, so a mild safety hazard.
To conserve battery you need an amplifier with a shutoff pin. These are always logic pins (DC on/off), which entails a diode/capacitor/resistor combination tuned to detect and convert AC input to on/off with a configured decay time, i.e. keep the amp powered on for X seconds without signal. Unfortunately the logic pins require high voltage relative to the power source (battery) and 0.77 Vrms just won't cut it. This then entails adding a transistor to shunt power to the shutdown pin from the battery. Then I had a look at a sample schematic of the TPA3116 amplifier, and there are so many pins to wire. At this point the project isn't any simpler than the linked instructable.
Then I found this:
https://www.rockvilleaudio.com/headrock/
According to the website it requires a minimum load of 16ohms, but that might be ideal for ferrite-core antennas. Perhaps I'll give it a try!
I hope someone attaches Bluetooth speakers to their shoes and locks every cart in target, so they have to remove the system.
https://hackaday.com/2016/03/04/social-engineering-your-way-...
Edit: looks like an Ardunio can do this with PWM too
Friends did this college in like 2005. Cambridge area, Shaws Market I think. I imagine the hardware setup was a bit different. All the details are hazy but I recall their lock transmission signal had a huge range and locked all carts in a wide area.
Based on what I recall, I believe there was one on the southeastern end of Green Street, a bit between Central and Kendall Square, barely northwest of MIT's primary campus area on the corner Massachusetts Ave and Vassar Street. That location has apparently closed in recent years.
https://www.instructables.com/EMP-shopping-cart-locker/
It might been the same text that somebody copy/pasted there, sounds vaguely familiar.
One of our local hardware store chains, Menards, have ramps in the form of moving sidewalks to allow customers to get fully loaded carts between floors safely and they seem to very reliably lock to the floor at the start of the ramp and unlock at the bottom. I've always been curious about the mechanism.
> Since 7.8 kHz is in the audio range
What is "the audio range" in the context of radio frequencies?
The range of human hearing is about 20 to 20000 Hz. As a by-product of producing physical vibrations at those frequencies (i.e. producing sound) via an electromagnetic coil, a speaker will produce an EMF with the same frequencies.
1. The phone's speaker generates a small amount of EM intereference at the audio frequency it's playing at 2. The sound waves hitting the locking electronics cause them to vibrate at that frequency and pick up random noise from the environment as a signal.
Either way, by using a frequency between 20Hz and 20kHz, everyone has some kind of "transmitter" that can generate mostly arbitrary waveforms.
https://apps.apple.com/us/app/radio-wave-sync/id1484233572
...basically: Turn up your phone volume, wiggle the phone speaker (which has magnets), magnets == signals => watch gets the right time from your phone instead of remote radio waves.
I've used the app a few times before and it's generally pretty reliable if you follow the instructions!
Shouldn't be difficult to find carts left near or beyond the edge of the parking lot.
I find the locking wheels annoying, because they're so often defective and make it a noisy struggle to get your cart through the store. But years ago I also had a neighbor in my apartment complex who would walk home with a cart every week, and would just leave (a dozen of) them there... she couldn't be bothered to push the empty carts back to the store, not even once. I'd think a $1 deposit/return system for carts would work better, and give the homeless in the area some gainful employment.
By hanging around in an Aldi parking lot and offering to return the shopping carts for people.