200 degree rotation 2DOF DIY

Hey guys! A few of my friends and I have started work on a 2DOF sim, but as it's quite unique, I figured I'd post the progress here for you guys to follow.

First we started out with the motor. I wanted this thing to roll all the way over on it's side, so linear actuators wouldn't work. I had an old heater blower motor hanging around, so I set about figuring out if it would be possible to use that.

This is the motor that we have:



My cousin and I went and measured the torque of the motor, and found it to be ~ 1 foot pound, with a rotation of 4400 RPM. I did some math with these numbers and found that the motor could provide 140 foot pounds at a speed of 30 RPM. Then, with the calculated moment of inertia, we found that this torque would be capable of accelerating the sim to full speed in 0.24 seconds - plenty fast for our use.

Once we found that the motor would me good enough for our needs, we set about finding a motor controller. With the motor clocking at 9.5 Amps when stalled, we found that this 13 Amp motor controller would suit us just fine: http://www.robotshop.com/en/cytron-13a-5-30v-single-dc-motor-controller.html

We also got an Arduino uno while we were at it, and as I have experience in programming, coding the Arduino wouldn't be an issue.

I then started on the design, which I based off of 1' conduit piping that we got given.


We were loaned a Logitech racing wheel set, that is pictured here. You can see the gearbox with the motor in it on the left. There will be another set driving the roll axis, but I haven't added it yet.

With that we started work. So far we have almost completed the frame:

After we mounted the shafts, we put it up on some temporary blocks to test the pitch axis:


I will continue to post progress as it happens.

Thanks guys!!

you're gifted! keep going

Your project has already started well
You do not seem out of space and equipment ...
Two is a good project!
Good continuation !

Votre projet a déjà bien débuté
Vous ne semblez pas manquer de place et d'outillage ...
A deux c'est un bon projet !
Bonne continuation !

Hi @Zoxks good start. Keep up the good work. Check your coins total.

Mike

Very good project ! I will follow.

Thanks for the support guys!

Hi. Looking good! I can't see what motors you are using though because it states DNS Error. But somewhere your math doesn't appear to add up. From what you stated, your stall current is 9.5 amps. I don't know your motors voltage, but the maximum voltage of your posted motor controller is 30v. So even at its maximum 30v and @ 9.5 amps stall current that would be around a 285 watt motor. But motors aren't rated at stall current so its rated wattage would be less. And even less than that if you're using less than 30v. That does not seem to compute with 30rpms @ 140 ft. lbs. torque. You shouldn't need that much torque with a joyrider design anyway though. May I ask how you measured your motors torque?

Good idea, continue, expect the results.

Well, it would be sad if they weren't big enough. The way we measured the torque is by attaching a one foot shaft to the motor, and using a scale to see how many pounds it pushed. It measured at around 1-2 pounds, so we went with the lower estimate of one pound.
We then used a high speed camera to see how fast it spun.

The motor is 12 volts at around 4 amps unloaded.

Oh and I realized that the motor spins at 4200 RPM. Not 4400. Sorry

Here is the motor:

It doesn't seem to like the URL, so I split it.

ama ++ zon.com/Four-Seasons-Trumark-35357-without/dp/B000C2O9I0

I have no experience with this kind of motion simulator but these motors seems a little bit light.

Neither do I

But, the motor does feel really strong when you are holding it, and it feels like it could be very very powerful with a 140:1 gear ratio.
Plus the math checks out. I guess only time will tell.

That’s a great way to test a motors stall torque @Zoxks! But while your math may be correct with the variables you used to calculate the torque, an assumption you made is what is incorrect.

Your assumption that the stall torque can be used to accurately calculate your running torque is wrong. An electric motor achieves its maximum torque at close to stall speed and its minimum torque, which is very little, at its maximum speed. That’s why an electric motor usually states a “Rated torque at a rated speed”.

So while your motor may achieve 140 ft. lbs with a gearbox, it will likely be at less than 2 rpm at the gearbox’s output shaft. When your gearbox is outputting 30 rpm, it will be at the motors maximum speed, and it will have little torque.

So assuming your testing was accurate, the question is not whether they will be able to move the intended weight, but whether they will be able to do it fast enough for proper simulation. My guess is that they will be to slow to satisfactorily simulate racing (at least for my taste) although they may be fast enough for flight simulation of at least commercial type aircraft.

One good thing though is if they are not fast enough to use on your simulator, a blower motor sounds like an excellent choice of motor for wind simulation.

You are quite right! But since we are trying to accelerate an object, we need the most torque when the object isn't rotating, and the least torque when the object is already spinning. What this means is that that the motor will have a high torque initially, but when the object gets up to speed, the torque will go down a lot.
I have made a graph to illustrate what I'm talking about (Its not quite accurate, but it gets the point across)

When the motor is at time zero, it has full torque, with a small angular velocity. As the object's rotation gets faster, the torque will decrease until the object has reached full speed. At which time we will have close to no torque, with a high velocity.
Like I said, this isn't 100% accurate, but it should capture most of what is going on.

By the way, thanks for the reply! It is very helpful to have constructive criticism.

I do see what you say though. Moment of inertia-acceleration calculation will be off because it isn't a constant torque. Hmm.

I guess I'll just have see though.

Okay. Got an update:

Started putting the gearbox togethe. We had to remove the flange on the motor and flip it around:


We put a Ft-Pound wrench on it and got 27 foot pounds! Not bad considering that the gear ratio at the moment is 27.04 to 1 (two 5.2 to 1 reductions)
Starting work on the carriage:

Mounting the gearbox:

And here is the finished carriage! We still have to hook up the gearbox to the seat. The gearbox isn't in its final position yet.

So exiting!

Progress quickly

Hey, so what do you guys think of this motor? It is a little cheaper and seems to provide more torque.
Motor
(Or if the link doesn't work)
http://www.ama ++ zon.com/AmpFlow-P40-250-Brushed-Electric-Motor/dp/B00D3ORQ2K

It does run a little slower, so I dono if I could get as much out of it. It also says it uses 250 watts, but the reviews said it pulled 2 amps running

also everyone was using a 10 amp speed controller with it.

A 36v, 250watt motor at 12volts is an 83watt motor. Its kind of hard to tell you what we think though when you are posting motors without rated torque specs.

Edit: It does state rated 24v, 250watts though so 125watts or so at 12v.

Hey guys! So we got the motor hooked up, and with a little bit of coding, got it to move the sim to specific locations!! I haven't tweeked the code at all yet, so that's why you see all the spring effect and such. It all should be able to be coded out.
I also think we will be running the motor at a higher voltage.