I have a project I want to get started on and would like some pointers from this community.
I have two pretty large windows by my bed and two roll up curtains covering them. What I would like to do with this project is
Connect a motor to each of the curtains
Connect a IR reciever to the system to open and close the curtains
After that I am thinking about hooking two or three lamps to relays and control them with the remote also.
Later on I would like to be able to control the system from my computer or even my phone
My problem is implementing the curtain-motor part of the project. I originally thought of using a servo (continuous modded or a regular one scaled down with gears). I am wondering if there is a better way to do this?
Is there a better type of rotational motor than servo?
The curtains are 100x120 mm (w x h) and have an aluminum bar at the bottom. Total weight I suppose not more than 0.3 kg.
Thanks for your reply. Can you refer me to something to get me started on what you mention?
Also, would a simple servo with a gear ratio much larger than one not cut it? Would it be too slow or would it not have enough power to lift the curtains?
Or maybe a small DC motor that gets external power. Maybe an induction motor?
What is the normal method of opening and closing the curtains manually - is it some sort of pull-cord system? If so, a small DC motor and reduction gearbox turning a pulley should do the job nicely. I've got a blind opener based on a Baby Orangutan and a tiny DC motor with an epicyclic reduction gearbox that only draws 100mA or so, with an nRF24L01+ transceiver to connect to a PC for configuration/logging - the whole thing is powered by a single cheap wall wart and the biggest component is the manual override switch; these things are tiny.
dingari:
Yes, there is a pull-chord system with a chord going around at the top and completing a loop at the bottom so you can pull up and down. My idea was to put a motor at the top and install it so it directly turns the bar and pulls the curtain up/down. Then I would have sensors at the top and at the bottom. Could I use a step motor to be able to pull it partially up and adjust it?
How much force is required on the cord to raise the curtain? Raising something heavy will require some heavy duty hardware.
dingari:
Yes, there is a pull-chord system with a chord going around at the top and completing a loop at the bottom so you can pull up and down. My idea was to put a motor at the top and install it so it directly turns the bar and pulls the curtain up/down. Then I would have sensors at the top and at the bottom. Could I use a step motor to be able to pull it partially up and adjust it?
How much force is required on the cord to raise the curtain? Raising something heavy will require some heavy duty hardware.
Can't be more than 0.3 kg overall that needs lifting. It spreads over a large surface. I'll attach a photo of the window.
Would a stepping motor be a good idea or could I use a regular DC motor to pull it partially up and down and adjust it?
A $5 servo modified for continuous rotation, a plastic jar lid modified to make pulley for the servo horn, a couple of limit switches might make up the basic hardware for your setup.
Stepper motors tend to be relatively inefficient (low mechanical output for a given electrical input) so I wouldn't go for a stepper unless size and power requirements were unlimited.
The key parameter you need to know is the maximum tension that you need to apply to wind the blinds up and down. The other parameter is how fast you need them to go up and down in terms of the linear speed of the chord. Add a safety margin, and that gives you something that you can use to determine the pulley size and motor torque/speed requirements. With these known, you need to figure out what combination of motor/gearbox/pulley you can physically package so that it fits the blind assembly.
