I hope I'm not in the wrong place. I'm planning a fairly simple project. At the moment I'm hesitating over the choice of motor and it's on this subject that I'd like to ask for your help. So here are the details.
As indicated in the title, it's a sliding solar panel system.
2 panels, one fixed on a flat surface, such as the roof of a van, the other superimposed on top. The panel on top has to slide across the width. Here are two images to help you understand: stacked panels unfolded panels
The sliding mechanism was chosen, a track system with glides made for outdoor use with very little friction. The panel weighs about 27kg, so let's count on 30kg. I intend to drive the panel with a rack and a notched wheel like the gate systems. The motor is the question. I found a planetary DC geared motor with the following specifications:
Model :32GP-31ZY
Product name: DC gear motor Voltage :12V
Speed: 1 RPM -2160 RPM Power :21.6W-24W
No-load current :0.2A-0.45A Maximum torque: 200. CM Shaft diameter :8MM Adjustable speed, reversible
Concerning the speed, I've calculated a distance to be covered of 1300mm, i.e. for a 45mm gear, ~141mm perimeter, 9 revolutions in say 30 seconds max, I think 15-20 rpm is enough for me. Or should I count on something higher and then reduce it?
I'm not sure about torque here.
Maybe you have other suggestions.
Thanks for your help.
Alexandre
Once the slide mechanism is built, it is no problem to measure the force required to move the panel, and compute the required torque from the gearbox output shaft.
Divide that by the gear ratio to get the absolute required minimum motor torque.
Note: motor torque is proportional to motor current, and you can reduce the average driving voltage to reduce the torque (also reduces shaft rotational speed).
I guess I understand Force et Torque and thank you for the tutorial btw.
But how to calculate it is another story. I know the weight of the panel (30KG) but on an horizontal plan to pull or push it is not like lifting a 30kg weight. If I understand well your tutorial, the panel will apply a Force on the shaft, but how do I calculate this ? And then what characteristics should I look for for my motor ?
These are great considerations but I am guessing far beyond what I really need for this project. Maybe I am wrong. But first :
should I use a stepper motor or not ? What would be the advantage of a stepper one beside precision which I don't necessarily need.
with or without brush ?
and then, I thought that your experience in project like this would suffice to advise on which motor to choose from, without really getting into calculations, but again, I might be wrong.
Only if you use a fish scale.
I don't know what the actual force will be but you probably want a scale with a max of maybe 5 or 10 kg and not something for weighing 100kg
If the panel weighs 30kg.
Then a 20kg scale will probably be big enough.
Or mount your panel on the slide.
Connect a wire/string from the edge of the panel in the direction of the slide and hang the end of the string over a pulley so you have the string hanging down.
Then put a bucket on the string.
1 litre or water is 1Kg.
