motors, what do do?

i'd like to build a 2DOF flight sim with full 360deg continuous roll and pitch

i'm trying to figure out my best options for motors given that i live in Thailand and we don't have access to stuff i can simply order on line (not without paying massive postal charges and import fees). so i'm trying to think of ways to use commonly available motors.

i guess motors are in 2 main camps, AC and DC.

low cost DC are most likely 12V automotive (or 24V golf cart). starter motors i think are problematic because of the huge current require to drive them. where else might i find a DC motor in the 500-700 watt range that might be in common use?

low cost AC induction motors are much easier to find. line voltage would be preferable i think because then the current required would only be a few amps so no problems for cheap slip rings. but i think controlling them is much harder, i would need directional proportional control and i have no idea how to do that.

the other thing is shaft rpm is pretty high on an un-geared induction motor so would be expensive to gear it down.

i wonder about a power drill? i can get a 700W variable speed, reversible power drill for $30 or so. i could replace the chuck with a gear wheel and build some kind of frame for the body, and the typical max rpm is a more manageable 800rpm or so. i'd still need to step that down to about 200rpm to be useful i think but that's only 4:1.

but i have no idea how to replace the trigger and direction switch with a signal from my arduino. has anyone tried this? this looks interesting


are there perhaps any other motor options i haven't considered? what is the best low cost motor option if i need about 200rpm and enough torque to spin a 200kg load around.

thanks

I cannot think of anything cheap that would do what you want to do - full 360degree continuous pitch and roll . You could try winch motors, but they are way slower than 200rpm.

the 200rpm assumes i use gears. my ultimate rpm will be about 30-40rpm which i believe is about the F16s roll rate (about 224dps). the winch motor is a good idea but still going to need a lot of amp to drive it i guess. i wonder what people use for a motor controller for that? and yes you are right, a joyrider design. thanks

360 deg sim? 12v winches might move it, but I think you may have to look at BIG 240v motors. You need to consider that you are moving yourself, frame, pc, screens, etc.
This is not going to be "cheap" but cheaper than buying one off the shelf.

240VAC induction motors would be my preferred choice but then back to the main question, how to control them from an arduino? does anyone know? thanks

i am just wondering and thinking about the cheap side...

some moment ago i saw a post of some guys that were "linking" small wiper motors to get hier torke... and since used wipers are really cheap if you get them from a car juncke yard...

i guess the thing would do the physics calculations...

i mean this could be silly... but maybe if you sum the torke of an arrangement of several motors maybe you could move a lot of weight.

http://i811.photobucket.com/albums/zz33/silvaedenio/atuador12v.jpg

http://www.voovirtual.com/t17642p45...homecockpit-com-fsx-ou-xp10?highlight=cockpit

i looking into wiper motors, the biggest 24V truck wiper motor i could find was about 100W and had about 10lb/ft torque, so basically it could lift a 1 pound load at a radius of 1 foot which is no where near enough to be useful.

anyhow, i have an old electric drill i pulled apart and i'm reverse engineering the speed switch and reverse switch. i'm pretty confident i can replace both with a 8 channel arduino relay board. i just realized i can use simple PCM (turning the power supply on and off quickly) to control speed. since its controlled from the microcontroller via a feedback loop i should be able to control it precisely and very cheaply

there are several huge advantages to using electric drills: cheap and powerful, low current AC mains so no transformers and power supplies, rpm can be geared to final rpm of 30rpm with a 30:1 gear. when i've got it working i will post the circuit.

My plan was to use 1 to 1.3 hp 24vdc motors with a gearbox. Then further reduction to the final speeds would be made with a chain and sprocket. The calculated maximum speeds necessary I came up with were 30 rpm for roll and 7 rpm for pitch (if I recall correctly). I think you will need about the same hp for both motors though because even though 7 rpm is slower and will achieve more torque, pitch will require more torque than roll since the length of your platform should be longer than its width. Pitch will therefore require a greater inertial force to get it moving than roll will. This assumes your platform design is a balanced one. When balanced, your motors main purpose is to overcome the inertia of acceleration. Once it’s moving it wont take much power to keep it moving the same speed. I picked up two 60 tooth sprockets to use for my final reduction (expensive though at $100 each on ebay but they are stainless steel because they were intended for use in chicken processing. Note: I would be willing to sell these if wanted). And while these aren’t the motors I bought, they are a good example of what should work (mine were motors that I add gearboxes to) http://www.ebay.com/itm/Tennant-Nob...090?pt=LH_DefaultDomain_0&hash=item19e9f66b72
These reduce to 200 rpm already so for roll, 200/30 = final chain reduction of about 6.5:1. And for pitch 200/7 = 28.5:1. So with a 60 tooth large sprocket the roll needs a 9 tooth small sprocket attached to its motor shaft. For pitch these motors actually won’t work though with a 60 tooth sprocket because at 28.5 to 1 you would need a 2 tooth sprocket on the pitch motor with is impossible. But you should see what I’m getting at here.

Also, do the slip rings you intend to use have a borehole thru them? If not, how do you intend the mount them so they will rotate with the center of the axis? Won’t you need an axle and bearing at this exact same spot to handle the rotation? That is why the slip rings I posted have a borehole in them the to allow the axle to go thru! My 60 tooth sprockets have a 3 inch hole in the center also to allow pass thru of the axle and slip ring. They have bolt holes drilled in them that would allow for attachment to a platform.

One more thing, I stopped working on this concept before I got around to ordering the slip rings so I’m not sure on exactly what is possible. The slip rings I posted earlier say they can be made to handle 15 amp circuits. The 1.3 hp 24vdc motor I bought has a 57amp rating. So I would need three or four circuits to handle them probably along with a common ground point. While these slip rings can do 24 circuits or more, my assumption is that with higher currents, they will not be able to have as many circuits on it. However, there will be two axles for each axis so you could use 2 slip rings per axis instead of one; of course, at a greater cost too though!


Ps I think you misstated something in your last post because 10 ft lbs torque means that the motor should lift 10lbs when attached to the end of a 1 foot lever.