Team 871 - Homebrew Segway

[Willum]

I think we talked about this before school let out B.

You need to keep feeding motor power out and not let the scooter freewheel. Gaining undesired momentum will add forces that are unexpected to the code. Say for instance going up or down a hill. The program, based upon angle of tilt, must tell you how fast to go.

DON'T USE FREEWHEEL!!!

btw, the FP's seemed powerful enough to dynamically balance, but just weren't programmed to come back hard enough under a limited tilt. I'm working out the bugs, but without the prototype to play with all i got is theory and roboemu code.

Will

[Matt Krass]

Ok, quick question, with 150lbs total load and 100rpm free speed with drill and FP together, what do you think it will run at under load? I'm hoping between 60 to 65rpm but I'm no expert...thanks.

[Willum]

Ok see here's where we start diving into unknown territory.

You never will have 150lbs of load with a 150lb rider. Following what I did. 666.4 newtons is the full force of the rider, multiply that by the cosine of the angle of tilt. your answer to that is your horizontal angle of force. Try it, follow what i did, just change the angle and you'll see how the force increases as the angle decreases.

Figuring out how torque, rpm, and theoretical force all come together... that's where i'm having a problem.

[Matt Krass]

Originally posted by Willum
Ok see here's where we start diving into unknown territory.

You never will have 150lbs of load with a 150lb rider. Following what I did. 666.4 newtons is the full force of the rider, multiply that by the cosine of the angle of tilt. your answer to that is your horizontal angle of force. Try it, follow what i did, just change the angle and you'll see how the force increases as the angle decreases.

Figuring out how torque, rpm, and theoretical force all come together... that's where i'm having a problem.

Uhhh.. I can add....? OK, wanna give us that in laymans? please?

[Willum]

hmmm... in physics there's a thing called normal force. That is, the force that pushes back at you. When you stand on the ground, your body pushes into the ground, but the ground pushes back up.

When riding the Segway or the Craigway the normal force is much different. Your body pushes straight down, always, but the normal force pushes back up from the axle at the angle you are tilted.

What I tried to say is that when you break up that angular force into it's two direction, horizontal and vertical, the horizontal force is never a full 150 pounds. If you tilt 10 degrees forward your horizontal force is about 26lbs.

I'm getting lost on how i get that force out of the motors... I've calculated out momentum, rpm, torque yadda yadda yadda...

So i guess those engineers get big $$$ for a reason. I hope that helped a little.

[sanddrag]

You probably know this already but I just didn't want anyone to forget the fact that the normal force is always perpendicular to the supporting surface.