How do I choose a motor type for my heavy lifting project?

I’m working on creating an interactive terminal for a public installation at my local library. It will be placed on a bookshelf with a keyboard and monitor inside. Two modules will rotate 90° when a button is pressed to reveal a terminal and keyboard hidden underneath (one module for each). Both will blend in entirely with the environment until the user activates the button on the side.

I’m extremely new to Arduino and struggling with choosing a motor type and the other key components to rotate the modules. I’m assuming I’ll have to purchase an Adafruit Servo/Stepper Shield, since it seems like it would make controlling and powering the motors easier and safer.

I’m still unsure what the best type of motor would be. I do intend to balance the back and bottom of the module in order to help it rotate more easily, but it is still slightly heavier than the standard hobby servo can lift. I'm also looking to keep it rather quiet, since it will be in the library and any noise will be noticeable even with added insulation. It doesn't need to turn quickly or be overly compact, but it can't run too hot either.

I suspect a generic window motor could work, but I'm really just guessing. They're relatively inexpensive and definitely powerful enough. Although, I'm not certain how quiet they would be or if I'm really on the right track. I also haven't found any tutorials or setups directly outlining how to control one with an Arduino.

I think I can use two limiter switch to stop the module when it open and closes, but I'm also uncertain how I would force it to stop if something obstructs the module (I wouldn't wanting crushing someone's hand).

It's a pretty ambitious first project, but I'm very passionate about seeing it working. Any advice would be greatly appreciated! :slight_smile:

I have used auto window motors several times to move large loads.
You should be able to get surplus motors like that for only $8.00.

Buy one and try it out.

Edit:
A project is like a living being, it grows, there are problems, you come up with solutions.
You have to design safety in the design.
You can use light beams, ultrasound distance sensors, trip wires, limit switches and load current sensors.
.

You control motors by controlling the current flowing through them.
For on off control, transistors and relays are often used.
Use PWM for speed control.
Reverse direction with a relay or H bridge.
1000s of hits on Google.

I think a small DC motor winding fishing line to pull up the device into it's resting position, then unwinding the line and let gravity putt it down into it's usable position. You could use woven steel fish line, which would last for years. Position limit switches to tell the Arduino when the shelf is in the proper position.

You did not mention how you intend to power this device.

Paul

I think that you need a geared motor or a motor plus gearbox to provide a high torque, low speed movement.

motor driven screw jacks can give enormous forces....

regards

Allan

physics is the starting point.
if your load is ballanced at all time, you do not need any motor. or the one you need can be the size of a toothpick.
if your set of encyclopedias weighs 100 pounds and is 2 feet from your axis, you need as much power as a small car.

I believe the Panama Canal, the original locks could be moved by one person and a burro.

That said, if your load is ballanced, there is very little chance of it falling and smashing fingers.
mechanically, to be safe, you would want to maintain a positive control at all times, with a safety valve of some sort.
that would means that a WORM GEAR is needed in the drive train. AND there would be no power applied by the drive a the closed position. this would allow tiny fingers to retain shape and not be crushed by the drive.

LarryD's post #1 hits the nail on the head. a window motor offers the power and quiet one would desire.
just connect it so that the motor lifts when closed and the motor power is not used to close.
maybe take some engineering from garage door openers and put a laser just above the closed line so that nothing could be crushed.

As a note, using some sort of release mechansim that would allow the whole drive to be manually moved is vital. people WILL force it and WILL break things.

I think you could get some sort of air chamber or hydraulics like a door closer to prevent it from slamming, and also allow a gentle settling to close.

Good introduction to force and torque here.