View Full Version : Rigging Railway Handcart Issues

 Mr-Bullfrog05-30-2006, 01:57 AMHi all, I'm working on this old fashioned railway handcart, the kind where you push and pull on the handle to make the wheels turn, however I'm having some real difficulties in rigging it. Basically I can get the wheel to turn with the bar that connects to the handle (Not shown in pic) to lookat the handle point it connects to, however I can't seem to have it control the actual handle movement, without getting loads of loop dependency errors. I thought perhaps there's some kind of trig function I can use to wire the wheels rotation to the handle, but it's been quite a few years since I did any trig! :shrug: Any thoughts or ideas would be greatly appreciated. I am working in Max but I would say the solution would be similar in other apps. Thanks again, Jeremy
McWolfe
05-30-2006, 05:34 AM
How about making a sine funktion, where the angle of the handlebar = sin(angle of wheels * constant1) *constant 2

constant1 = how fast the handle oscilates
constant2 = the amplitude of the handlebar.

McWolfe

Mr-Bullfrog
05-30-2006, 09:33 AM
Hey,

Thanks for the reply. I thought it would probably use a sine function, just 'cause I remember what the waveform looks like, but wasn't sure how to apply it. Was wondering though what you meant with the constants?

constant1 = how fast the handle oscilates

Not sure what you meant by this? I'm wanting to control the oscilations based on the wheel rotation, with a single up and down action for each full revolution of the wheel. Would this value therefore be 1, or 360 degrees? (Or 360 degrees in radians?)

constant2 = the amplitude of the handlebar

Would this be the rotation of the wheel? Or the minimum and maximum angles of the handlebar?

Also, I was assuming the radius of the wheel would fall into place somewhere in the function, or is this not required?

Thanks heaps for the help,

Jeremy

McWolfe
05-30-2006, 12:14 PM
Not sure what you meant by this? I'm wanting to control the oscilations based on the wheel rotation, with a single up and down action for each full revolution of the wheel. Would this value therefore be 1, or 360 degrees? (Or 360 degrees in radians?)

I'm a bit rusty here, but C1 would basically represent the number of oscillations/ rev. It should be 1 as long as you are using the same unit.

Would this be the rotation of the wheel? Or the minimum and maximum angles of the handlebar?

The later. Since the sine-function goes from 1 to -1, you will want to multiply with a number equal to the maximum angle of the handlebar.

Also, I was assuming the radius of the wheel would fall into place somewhere in the function, or is this not required?

Thanks heaps for the help,

Jeremy

The radius of the wheel isn't required. The relation wheel - handlebar is the same no matter what the radius of the wheel.

McWolfe

05-30-2006, 11:10 PM
I created a super simple IK system for your cart, let me know what you think if it. It's really simple. If you have any other question, let me know.

Mr-Bullfrog
05-31-2006, 06:53 AM
Hey,

Thanks very much to both of you. I really like the method you came up with illusion, and will probably be using that (Elegantly simple, very nice!)

Again, just wanted to say a huge thanks for the help to both of you! Definately saved me many more frustrating hours!

Kind regards,

-Jeremy

McWolfe
05-31-2006, 07:23 AM
I created a super simple IK system for your cart, let me know what you think if it. It's really simple. If you have any other question, let me know.

Nope.. that's a baaad solution.. you can't use that!!!

(actually.. it is a great solution, apart from the fact that it wasn't ME that came up with it ;-) )

McWolfe

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