Jump to content

  • Log In with Google      Sign In   
  • Create Account


Rotational motion to linear motion


Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.

  • You cannot reply to this topic
6 replies to this topic

#1 Lars-Kristian   Members   -  Reputation: 158

Like
0Likes
Like

Posted 20 July 2012 - 07:04 PM

Hi, like my title says I want to transform rotational motion in to linear motion.
In my game I have a circle that spins, and when it collides with something, it shall transform some of that spin in to a linear motion.

test.jpg

I have tried alot of different things, and I'm out of ideas. Does someone have a solution?
And I'm using a verlet integration for physic's if it helps.

Sponsor:

#2 medevilenemy   Members   -  Reputation: 301

Like
0Likes
Like

Posted 21 July 2012 - 10:42 AM

I'm assuming what you want is for the circle to roll along the surface. I think what you need is to model the friction between the object and the surface, and the torque with which the circle spins. On contact with a surface of nonzero coeficcient of friction, the friction generated will tend to produce a torque opposite to that being generated by the circle (or whatever is causing it to spin). When the circle's torque overcomes the frictional torque, the circle rolls including a certain linear component. Unfortunately I don't have the math handy, but a physics textbook or google should help.
There was a saying we had in college: Those who walk into the engineering building are never quite the same when they walk out.

#3 Postie   Members   -  Reputation: 745

Like
0Likes
Like

Posted 21 July 2012 - 06:44 PM

The counter intuitive thing about rolling vs sliding is that initially when the circle is stationary relative to the surface the friction force that comes into play uses the dynamic (or moving) friction coefficient. That force causes an unbalanced torque on the circle that causes an acceleration along the surface. Eventually, the speed of motion along the surface opposes the tangential velocity of the point of contact and that point can be considered stationary relative to the surface, so the dynamic friction coefficient is replaced by the static friction coefficient. This removes the torque, so the circle stops accelerating.
Currently working on an open world survival RPG - For info check out my Development blog: ByteWrangler

#4 Lars-Kristian   Members   -  Reputation: 158

Like
0Likes
Like

Posted 22 July 2012 - 05:08 AM

Thanks for the reply, but im still not sure how to achieve this effect.

This is my ideas:
test2.jpg

#5 Kyall   Members   -  Reputation: 287

Like
0Likes
Like

Posted 23 July 2012 - 02:24 AM

Angular momentum beecomes linear momentum dependent upon the friction pretty much so look up andlgular 'moment' i think is the techinical term in physics stuff to get the equation that gives you that angular momentum

just googled it, take a look at moment of inertia on wikipedia, that should point you in the correct dorection; id.post.the equations but my physics book is not at.the location i am currently chillin sorry - also phone so srry about the typos
I say Code! You say Build! Code! Build! Code! Build! Can I get a woop-woop? Woop! Woop!

#6 Bartpab   Members   -  Reputation: 109

Like
0Likes
Like

Posted 23 July 2012 - 09:23 PM

With a simple kinematic way, V = k*R*W where 0 < k < 1 which can be a sort of transmission factor, R for radius and W for the rotation speed. :3

#7 Lars-Kristian   Members   -  Reputation: 158

Like
0Likes
Like

Posted 24 July 2012 - 02:50 AM

Thanks for all the help everyone, but i did it my way, and it ended up working the way I wanted to. :)




Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.



PARTNERS