I disagree. I know it's all past news now and doesn't even matter, but I would have done it differently. I would have ignored the motor, the drive amp, and all the rotational stuff at the left end of the track. I would have also ignored the viscous damping.

Focus on the forces required to keep the pendulum vertical. Write those equations first in a perfect simplified world and then once you have that part done add in the complexity of the damping and a rotational drive. But to start, assume linear motion, frictionless surfaces, and no damping. First task is to just keep the pendulum upright. Once you have that, add in the other factors one at a time.

I'm more of a Herman fan but it is similar to Far Side..... Binky the bunny is best

 

 

After a few minutes of trying to balance a pencil on my finger and thinking about the boundary conditions, I gave up. After all it was beer time. But modeling the system in Matlab was required. I don't own Matlab but it's said to be a very powerful program. Maybe fluency in its use would be a big advantage in solving the problem.

Haha!! My engineering sense tells me that the boundary condition would be when/if the pendulum ever reaches forty-five degrees to horizontal. Beyond that, it would be unrecoverable because the force pulling down would be greater than the force you could ever create even if you moved it laterally at infinite speed. At least that's what the vectors in my head tell me.

And you're right! It's beer time!! Right now! Good night folks!!

She had a partner for the project and he didn't have any idea either and became a mute when presentation time came around.

This is one of the few classes she has struggled in and she hasn't gotten along with the professor like some of her classes. I am sure some of that plays a part too.

Graduation is Friday but her last exam is Friday morning so in reality, you walk but don't even know if you've graduated until days later.

6 minutes ago, Patcon said:

in reality, you walk but don't even know if you've graduated until days later.

My son who recently graduated from VT went through that exact same thing. There was one class that was questionable up to the end and nobody could be 100% sure until the diploma arrived in the mail.

Hope it all works out!!

12 hours ago, Captain Obvious said:

Haha!! My engineering sense tells me that the boundary condition would be when/if the pendulum ever reaches forty-five degrees to horizontal. Beyond that, it would be unrecoverable because the force pulling down would be greater than the force you could ever create even if you moved it laterally at infinite speed. At least that's what the vectors in my head tell me.

And you're right! It's beer time!! Right now! Good night folks!!

Not sure I agree.  The component that reverses the pendulums fall to the ground is the acceleration of the cart, not velocity.  Velocity does nothing for you in this pendulum scenario, it's all about the cart acceleration. With a constant velocity, the mass will always fall.  At 45 degrees, the acceleration of the cart will need to be greater than 1g.  The greater the acceleration, the quicker the pendulum mass will return to vertical.  Also, I think the acceleration of the cart will determine the pendulum period of oscillation.

Too early for a beer here ☺️

Edited April 30, 20195 yr by motorman7

1 hour ago, motorman7 said:

Too early for a beer here ☺️

Oh, it's five o'clock somewhere!!!

Mission accomplished

19 minutes ago, Patcon said:

Mission accomplished

Female with an engineering degree - the world is her oyster.  Huge congrats to her and her parents.

Dennis

15 minutes ago, psdenno said:

Female with an engineering degree - the world is her oyster.  Huge congrats to her and her parents.

Dennis

Thank you. She is working on going to Kentucky for her doctorate, otherwise she will stay at Bama

58 minutes ago, Patcon said:

Thank you. She is working on going to Kentucky for her doctorate, otherwise she will stay at Bama

My engineer son got his Bachelor's and Master's in four years at USC (the one in California), decided that was enough school for a while, and has been in the workforce since 2015.  I like to point out to him that his starting salary was about the same as what I had worked up to after 30+ years on the job with my Master's degree.  Engineers are in high demand.  Today, he's flying back from Montreal where he had spent a few days shopping for satellite dishes for his company.  As I often say, "It's good to be him.".

Dennis

Edited June 15, 20195 yr by psdenno