Why oh Why can't current technology produce a supermarket trolley that goes the way you want it to?

Question

We've sent men to the moon, (though the conspiracy theorists may argue with that) we've sent remote probes to Mars, we've produced robots to make cars, and a million other technological marvels, but still we don't seem to be able to produce a supermarket trolley that you don't have to wrestle with to keep it going in the direction that's required.

What *is* the problem, guys?

P.S. I can't seem to find an appropriate category for this, so this one will have to do.

Oh my god, the half wit SMD is back. Hasn't got a single thing of intelligence, wit or interest to contribute, but insists upon doing it anyway.

Answer 1

I'd guess the main problem is cost. Both manufacturing and maintainance. Remember, a supermarket have to buy trolleys, but get no return on them, so they're looking to buy the cheapest thing possible which will do the job. They'll spend money on anti-theft devices because it saves them money in the long run, and maybe a little more than base-line if they think it will attract customers, but no supermarket is going to pay for the R&D and production of the perfect supermarket trolley, because for them it just isn't worth it.

Answer 2

It is possible to produce a supermarket trolley that goes the way you want, the problem is not with that, the problem is how you communicate "the direction you want it to go"? to the trolley.

This is the missing link.

Airport trolleys usually have castors at the front, and fixed wheels at the back. The person pushing the trolley pushes with two hands, placed at the rear, spaced so that the left hand is near the left side, and that the right hand is near the right side. These are quite easy to keep in the right direction, as the rear wheels are always pointing towards the front wheels, and the sum of the pushing of right and left hands will control speed, and the difference in pushing (between right and left hand) will control steering direction, and you can go quite fast without losing control and crashing.

So a clear way of communicating speed and direction to the airport trolley is available to the user by adjusting the forward push on left and right hands.

However, in supermarkets, speed is not required, and manouverability is important.

Hence supermarket trolleys have castors on all four wheels, so that they can be pushed in any direction from standstill. This means that speed and direction are hard to control, as there is no "straight ahead" position for any of the wheels.

This idea has two basic problems, the first is "how you communicate to the trolley the direction you want it to go?".

The second problem is that with all wheels freely steering, then any additional friction on one wheel will severely affect the trolley's ability to be pushed in a straight line (keeping the trolley in line with the direction of travel). Such additional friction may be in the form of unequal, or lack of lubrication of the castors and wheels; and also in the form of some debris wrapping itself around one of the wheels or castors, causing extra drag on one wheel.

The second problem exacerbates the first, as the second problem calls for corrective control measures, when we still have no satisfactory method of comminicating desired direction to the trolley.

You're right, before we make a vehicle, we should think about how the user will communicate desired direction of travel to it.

Answer 3

supermarket trolleys are designed to go the wrong way taking you round the shop thus "helping" you to buy things you don't need or want.

Answer 4

the problem is less technology and more biology. The trick is the interface between the cart and the brain. Plus, do you want the cerebral implants necessary for that?

Answer 5

Hhaha oh that is just too funny. I ask myself the same question all the time. I take my husband grocery shopping with me and give him the cart thats my solution. I just can't handle those things. call me clumsy but thats how it is.