I am trying to constrain motion for the following design:
Object constrained to vertical motion (a counterweight).
Object constrained to horizontal motion along a track (a slider).
A cable runs from the counterweight upward, makes a 180-degree turn around a pulley, runs back down, makes a 90-degree turn around another pulley, and connects to the slider.
When the weight moves down 10 cm, the slider needs to move laterally 10 cm.
I don't care about modelling the cable, but I do need to have the slider move as the weight moves.
I will also need to model a case with a more complicated pulley, where when the weight moves down 10cm the slider moves laterally 5cm (again I don't care about the cable, just the relative motion).
Is there a way I can do this without creating a series of planes and cylinders and using rotation - translation constraints to link the motion of the weight to the slider?
Solved! Go to Solution.
I was able to get it to work by creating two motion constraints, one between the weight and a simple extruded circle, and another between the extruded circle and the slider. I then made the extruded circle invisible and now I can move the weight and have the slider also move - perfect!
You can also do this with a constraint Parameter (don't really need the dummy part).
I'm afraid I don't understand. The only way I know how to apply a constraint to something that moves in a straight line it to associate that object to a rotational object using a motion constraint. Can you give me more details about how to do this without a dummy part?
Attach your assembly here.
There are two straight beams forming an L
I would like to be able to move one and have the other move, but at a different rate (say, twice or thee times as fast).
Does anyone understand what JDMather is referring to? How might I use a "constraint parameter" to achieve the relative motion without a dummy part?
The assembly you attached references a base.ipt which you did not include in the attachment.
Since the assembly was not complete and therefore I didn't understand your design intent - I remove extraneous stuff and made up an example.
In the attached find the Drive This constraint and right click on it and select Drive Constraint and then hit Play (or Reverse Play).
I only spent 5 minutes on that right before a meeting - so not much there and not really any logic, but you will notice that I named a couple of dimension Parameters and then made one a function of the other.
You can make any mathematical relationship you need in the constraints (or any parameters). Just watch out for units agreement (this is the most common problem posted here on the forum).
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