Author Topic: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated  (Read 11716 times)

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Offline EEVblogTopic starter

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EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« on: February 25, 2020, 12:14:11 am »
Dave's local shopping centre just installed shopping trolleys with electronic locking wheels fro ma company called Gatekeeper System, how does it work?
Teardown time!
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Offline steve30

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #1 on: February 25, 2020, 01:00:27 am »
Nice video.

I remember starting to see these kinds of things in the 2000s. There used to be a Tesco in the next town which had various signs up telling people their trolleys will stop beyond this point.

Here's a photo I took of such a sign back in 2008. I thought this particular one was rather amusing :).
 

Offline Stray Electron

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #2 on: February 25, 2020, 02:14:00 am »
   The Walmart near me is about 1/8 of a mile from a very large university and the students keep stealing their shopping carts (a trolley is something you ride!)  They tried the locking wheels but gave up. Supposedly, the students were running with them and they claimed that when the wheels locked up the carts would flip and send the students flying in the air and they were getting injured from the fall and threatened to sue Walmart.

  Yeah, another piece of the growing legal idiocracy in the US.
 

Offline Muttley Snickers

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #3 on: February 25, 2020, 02:49:34 am »
The system does appear to work, the local Coles has wheel lockable trolleys and I've never seen one of theirs outside the carpark perimeter, plenty of Aldi trolleys around the neighbourhood though. I really wished they also incorporated a permanent brake so people would have to hold a lever to release the wheel lock, of course they would also need to incorporate an override for the trolley collectors as well.

An example of somebodys blatant stupidity below.
https://www.ozbargain.com.au/node/440923
 
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Offline EEVblogTopic starter

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #4 on: February 25, 2020, 03:12:07 am »
The system does appear to work, the local Coles has wheel lockable trolleys and I've never seen one of theirs outside the carpark perimeter, plenty of Aldi trolleys around the neighbourhood though. I really wished they also incorporated a permanent brake so people would have to hold a lever to release the wheel lock, of course they would also need to incorporate an override for the trolley collectors as well.

My shopping centre only has Coles and there are dozens of trolleys littered outside the carpark. Doesn't seem to work here.
 

Offline jhalar

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #5 on: February 25, 2020, 04:27:37 am »
I've seen a trolley with the lock wheel being pushed through the streets outside of my local Sydney shopping centre.
Two people lifting the wheel off the ground while one person was pushing the trolley.

I thought that all three of them could have carried the shopping bags easily.
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Offline johnlsenchak

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #6 on: February 25, 2020, 04:37:42 am »

My original  thought  before  you  cracked  that the wheel open, is that the  it would spin  turning the DC  motor  which then would charge the battery as the shopping cart (trolley)  was used  on a daily  basis going  up and down the   aisles in  the store.   
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Offline JustMeHere

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #7 on: February 25, 2020, 07:58:01 am »
The system does appear to work, the local Coles has wheel lockable trolleys and I've never seen one of theirs outside the carpark perimeter, plenty of Aldi trolleys around the neighbourhood though. I really wished they also incorporated a permanent brake so people would have to hold a lever to release the wheel lock, of course they would also need to incorporate an override for the trolley collectors as well.

My shopping centre only has Coles and there are dozens of trolleys littered outside the carpark. Doesn't seem to work here.

Maybe they are outside of the car park because the wheels locked up and were left.

I wonder if you can open them with heat.
 

Offline ogden

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #8 on: February 25, 2020, 06:23:43 pm »
2.4 GHz radio could be beacon for direction-finding
 

Offline nctnico

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #9 on: February 25, 2020, 08:25:30 pm »
Nice video.

I remember starting to see these kinds of things in the 2000s.
I think I've seen them over here (in the NL) too but all shops have trolleys which are chained together and you need a coin to unlock a trolley nowadays.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Stray Electron

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #10 on: February 25, 2020, 08:44:34 pm »
  We have a few of those too but you'd be surprised how many people (including the ones that don't take them out of the store parking lot) won't return them to the rack and get their quarter (1/4 of a dollar) back.
 

Offline james_s

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #11 on: February 25, 2020, 08:56:14 pm »
They should put a fully refundable fee of a few dollars on the cart to get people to return it, I hate it when I'm trying to park and there are shopping carts randomly scattered around the parking lot, people are so lazy.

I didn't realize carts were $500+, that's pushing up on felony theft territory. Maybe if they started prosecuting a few people others would get the message.
 

Offline ogden

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #12 on: February 25, 2020, 09:18:58 pm »
They should put a fully refundable fee of a few dollars on the cart to get people to return it
It works very well for a lot less money. When lazy leaves cart, poor or just kids will return it to get a coin.
 
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Offline mikeselectricstuff

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #13 on: February 25, 2020, 09:48:20 pm »
I didn't realize carts were $500+,
They aren't. That figure came from reports of trolleys full of goods being stolen, not the trolley
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Offline thm_w

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #14 on: February 25, 2020, 09:58:02 pm »
  We have a few of those too but you'd be surprised how many people (including the ones that don't take them out of the store parking lot) won't return them to the rack and get their quarter (1/4 of a dollar) back.

Its $1 here, I think no one cares about 25c now. Too bad $1 coins in USA are relatively rare otherwise they'd switch to that.
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Offline nctnico

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #15 on: February 25, 2020, 09:58:26 pm »
I didn't realize carts were $500+,
They aren't. That figure came from reports of trolleys full of goods being stolen, not the trolley
Trolleys are rather expensive. Not $500 but not much less either. It seems $200 is the low mark.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Offline magic

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #16 on: February 25, 2020, 10:20:40 pm »
In related news, I had never seen a supermarket trolley outside the supermarket's parking lot until I went to America :P :box:
 

Offline Cerebus

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #17 on: February 26, 2020, 12:05:57 am »
2.4 GHz radio could be beacon for direction-finding

Direction finding so that the trolley can steer itself any direction except the one you want it to go?  :)
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Offline Mr.B

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #18 on: February 26, 2020, 12:24:39 am »
... so that the trolley can steer itself any direction except the one you want it to go?  :)

I thought the low tech models already did this.
They all do at my local supermarket...
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Offline texaspyro

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #19 on: February 26, 2020, 03:00:34 am »
I saw a  fully mechanical version of these.   They buried strong Nd magnets in the pavement that interacted with a magnet on a locking latch on the cart.   Cross the magnetic barrier and the wheels lock.  It took a special tool to unlock the wheels.
 

Offline Gary350z

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #20 on: February 26, 2020, 05:32:59 am »
I was looking at these a while back. Here is some more information.

How it works:
Anti-Theft Device Keeps Shopping Carts on the Job - Science Channel
https://youtu.be/PWZOeM5jdjg?t=71

Teardown:
The Wheel Locking Wheel Teardown - The Workbench
https://youtu.be/XMHzb5S7X04

How to hack the system and lock all the carts at the same time >:D:
EMP Shopping Cart Locker - Instructables
https://www.instructables.com/id/EMP-shopping-cart-locker/
 
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Offline G7PSK

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #21 on: February 26, 2020, 02:26:29 pm »
The local super markets around here just put knobbly paving at all points of access which makes it extremely hard to push the trolleys any further as the wheels jam and jitter on the knobbly surface cars can drive over it and people can walk on it but the spacing is just right to catch shopping trolley wheels which don't require expensive braking systems or buried coils. The other thing the often have is requirement for a coin or token to unchain the trolley, seems a pound is worth more to most people than a \shopping trolley.
 

Offline ogden

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #22 on: February 26, 2020, 10:39:12 pm »
2.4 GHz radio could be beacon for direction-finding
Direction finding so that the trolley can steer itself any direction except the one you want it to go?  :)
To steer in any direction you don't need direction finding. Just steer. [edit] ;)
« Last Edit: February 26, 2020, 10:41:03 pm by ogden »
 

Offline thm_w

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #23 on: February 26, 2020, 10:59:34 pm »
I saw a  fully mechanical version of these.   They buried strong Nd magnets in the pavement that interacted with a magnet on a locking latch on the cart.   Cross the magnetic barrier and the wheels lock.  It took a special tool to unlock the wheels.

Thats what I had always assumed, it was a simpler mechanical brake. But then, wouldn't that area get filled with ferrous debris?
Also if the magnets were strong enough, could potentially trip someone with unusually thick metal shoes or cane. So they can't be too powerful.
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Offline Maxlor

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Re: EEVblog #1287 - Gatekeeper Shopping Trolley Lock Investigated
« Reply #24 on: February 27, 2020, 12:09:54 am »
Dave: your recording shows an 8 bit code. That code is probably store-specific and doesn't match the wheel you were sent. So maybe try all 256 possible codes? Also the installation pictures show just a burried cable (multi-wire actually, so how does that work? Wouldn't the fields cancel out?), so maybe using a speaker instead of a wire with enough current running through it isn't optimal?

Now, if I wanted to generate a signal with all 256 patterns, I'd probably write a program to generate a wave file.. But you have access to fancy function generators. Maybe use this opportunity to demonstrate how they can generate this signal with very little effort? I mean, you keep saying every so often that that part of the value of good test gear is that it saves time.
 


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