Food lift in a restoraunt

Hi everyone,

First of all I am new here and this is my first post so if I posted it in wrong part of forum I am sorry.

So I was wondering can I make an lift controlled by an arduino?
Things I would use are :

Nema 42 stepper motor with following controller and Arduino MEGA 2560 REV3

Can it be done?
I have only 2 stops and it is ground and 1st floor but what I need is that my motor starts slowly then accelerates to certain speed and then slowly slows down until full stop because of the certain food that can be spilled if lift doesn´t stop at slow speed...

What do you think? Should I use something else?

Best regards

Sounds like a perfect job for Arduino. Have at it.

some Hall sensors to detect exact floor level? with magnet

Spajky56:
Nema 42 stepper motor with following controller and Arduino MEGA 2560 REV3

I would not use a stepper. motor cost is very expensive.
stepper driver for large stepper motor is very expensive
power supply for larger stepper is very expensive.

I would suggest a brushless DC motor, with driver.
and use a brake / clutch (lots of ways to do that)

use an grey scale encoder on the shaft for feedback of speed and position.
use multiple switches for position verification, end stop, etc

the general idea is to hit a 'home' switch to know where you are.
ramp speed up to desired speed,
ramp speed down for final destination
stop at the 'other stop' and verify with an end switch of some sort.

all this is not Rocket Surgery and could be done by a beginner.
I would rate this as an advanced beginner project.

make it work, tweek the ramp speeds and switches as you go.

(deleted)

Hi,

Spajky56:
So I was wondering can I make an lift controlled by an arduino?

Yes.
First off, you need to specify the maximum weight of the lift when full.
Take that figure and double it to be on the safe side (who knows what's going to get jammed into the lift!)

Decide on how the lift mechanism will operate, maybe some winch arrangement. If so, what is the diameter of the winch pulley... from that you can work out the torque required from the motor.

I guess you will need a motor+gearbox.
You could look at some 12V electric winch and modify it.
(link is not a recommendation, just the first hit in google).

If you are building it all yourself, then a stepper+gearbox would be somewhat simpler than a DC motor+gearbox+brake+encoder. However, you may be required to fit a brake anyway.

Last important note: Check regulations in your area.
There will be health and safety requirements for fitting a lift in your workplace.
At least you will have to provide safety interlock switches on the doors to the lift shaft. It is likely you will have to fit electric or mechanical locks on the doors as well to prevent them being opened while the lift is in transit.

Yours,
TonyWilk

Considering the control hardware is almost certainly the cheap bit of a lift, why not ask a proper lift company to install it for you? Then if something goes wrong you didn't do it.

You need a lift car, shaft, guide rails, wench, doors, and various detectors to know where it is. That input all goes to your controller. Then you need to write your software to control the lift safely.

Lifts should never be allowed to move when the doors are not fully closed.

The doors should be locked shut when the lift is not at the correct location for those doors to open.

Lifts of course need various protection mechanisms to prevent them from falling even if all wires are cut (passenger lifts at least - this kind of cargo lift, if too small for even a really small person to squeeze into - yes, people will try if they can - maybe not).

I liked your idea, can you please explain it in detail?

guide rails, wench,

A dumb waitress? :smiley:

GrooveFlotilla:
A dumb waitress? :smiley:

She gotta be smart enough to press the buttons :slight_smile:
Winch. I meant winch of course. The i and e are just too close together on the keyboard... slip of the finger.

The i and e are just too close together on the keyboard

On which keyboard? On my keyboard, there are 4 keys between them. Not that I haven’t used that excuse… 8)

Or that I mind having a wench around, when needed.

True. Both wenches and winches can come in useful at times.

wvmarle:
She gotta be smart enough to press the buttons :slight_smile:
Winch. I meant winch of course. The i and e are just too close together on the keyboard... slip of the finger.

Sure, sure, Freudian finger slip.

Your point about the doors being locked is good, particularly the ground floor door. No point in somebody getting decapitated if the wench fails.

A NEMA 42 is not a large motor. I sincerely hope this is a tabletop-sized school project and not a real lift.

ardly:
Sure, sure, Freudian finger slip.

It seems I'm not the only person with that problem :slight_smile:

Your point about the doors being locked is good, particularly the ground floor door. No point in somebody getting decapitated if the wench fails.

I was more thinking of people or food falling into the lift shaft from the upper door (OK, it's probably not a 30-storey building but still), or the lift starting to move while someone has their hands still in it.

...particularly dangerous if there is a 'call' button on each floor and anyone can push any button at at any time.

Absolutely. That's why the "never allowed to move when a door is open" requirement.
With just two stops it's easy, with more stops smarts have to be included to decide on which floor to go next.

The more you think about a lift the more you realise there is to the project.

A counterweight will reduce the size of motor required, but it still needs to be able to cope with a fully laden list. Liquids, soup/wine/beer are surprisingly heavy.

Some kind of overload sensing is probably required because you can be sure somebody will try and stick something stupid in the lift (even a person if that is at all possible).

The brake should operate on the rails not the motor, gears or cable, so that it can cope with the cable breaking.

The brake should be held off during motion so that it will be applied when the lift stops or there is a loss of power.