I just finished building my newest robot and it work amazingly well, it is a model of a centrifuge accelerator thing that people use to test g force. It spins very fast and has four motors to drive it.

I am thinking about putting a limit switch under the arm so that i can calculate the exact speed of the arm by finding the amount of time it takes to do 1 revolution.

Each gear in the design reinforces the other by spinning the opposite direction resulting in a lot of speed and torque.

I had to attach a 25lb weight because it is so powerful that it flipped a 10 pound weight over.

Here are some pictures

Tell me what you guys think of this, i was tired of building the same old tank tread design so i went and thought of building a machine like this.

I do not know of anyone who has made anything like this

nice!!! ive been planning on building a stationary robotic arm with 5DOF or so :smiley:

Do you have motors attached to all 4 of the visible gears? The 84 and 36 tooth ones? If so you may be damaging your motors. At least two of them wouldn’t be giving you any effective power.

Ha, blew away a 10 lb weight, that must be powerfull.

why not an optical encoder? wait for the quadrature thing to comeout first though

I will try and attach an optical shaft encoder, i don’t know why i didn’t think of that.

Yes there is four motors on each of the gears, they each spin at the same speed so i don’t see how they are being damaged. If the accelerator is under stress the 2 motors on the 36 tooth gears will help out by keeping the 84 tooth gears spinning at the same speed.

I am waiting for the youtube video of this thing to process, once it is done i will post the link so that you guys can watch it.

lol we all forget stuff :smiley: :rolleyes:

Alright here is the youtube video

Please tell me if you like the video


very nice… it’s a little wobbly though, i bet if you were able to keep the main acle streight, it would go a little faster

awesome!! if you’re using an accelerometer, cant you count a full revolution when the accelerometer output is the same as start? i.e. axis 1 is at 0.1V at start then 2.5V at the end then goes back to 0.1V

thats just an example but wouldnt that work? You could also do this with digital signals

That is an excellent and very imaginative robot! What RPM does it spin at? You can also measure its speed using a strobe light.

wow thats awsome very fast great job

I am going to try to measure the speed now.

Someone said that i should strengthen the middle gear so i will do that as well.

After that i am going to take this apart and build something else, i sit for like 30 minutes thinking until i come up with ideas like this.

lol so do i some times longer

Add a counter weight so it doesn’t wobble.


The problem I see with the way you have the motors set up is this: By attaching the motors to
different size gears that drive the same gear you are try to use a gear reduction but it’s not really working correctly.
Because: when you attach a motor to say and 84tooth gear and they run a 36tooth gear off the 84 tooth one the 36tooth gear will turn 2.3 times for every turn of the 84toothe gear. That is in essence “faster”. However if you then attach a motor to the 36tooth gear and keep the motor on the 84tooth gear you are now, in addition to driving the 36tooth gear, you are driving the motor attaching to the 36tooth gear. So either

A. the motor attached to the 84tooth gear runs slower and the one on the 36tooth gear runs at normal speed, or

B. the motor attached to the 84tooth gear runs at normal speed and the motor on the 36tooth gear will be overdriven, it will try and go faster than it wants to.

Situation A is more likely, either way it’s not working the way you expect it to.

Also, the bot should actually spin faster if you change the smaller gears to larger ones because you lose the drag of the two motors with the smaller gears.

Either way the robot works good and it spins fast.

If i had more room on the bottom i would have used larger gears, but this thing already spins very very fast so much that it wobbles the 25lb weight off of the table.

Well i am calculating the maximum speed that this thing is capable of and i should have an answer in about an hour.

I just finished strengthening the middle gear and axle that it spins on, i also added an optical shaft encoder for speed calculations.

Here are some pictures

Tell me what you think of the new improvements.

I finished calculating the speed and rpm of this robot.

RPM = 813.6
Radius = 11.5in
Circumference = 72.3in per revolution or 6ft per revolution
Feet per minute = 4898.8ft
4898.8/5280 =.9278030303
.9278030303 x 60mph = 55.7mph

Total Speed = 55.7mph
Total RPM = 813.6

holy !@#$ thats amazing, 55.7mph!!! are you sure you have that right???