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3D contacts and spring related questions

Question asked by Vio Vivio on Jun 27, 2010
Latest reply on Jul 16, 2010 by Vio Vivio



I have a robot structure that looks like a ball with multiple legs mounted on it and I intend to simulate it in SW2008.


The problem is that I feel quite uncomfortable with the motion layout in SW2008, maybe less now since I got the manual.

Hope that in a week or so I'll understand it finally (more or less).


To make my life easier, first I intend to simulate the structure presented in this video


Now, let me describe a little the mechanism that makes me sleepless.
1 - the base (black color)
2 - the leg (red color)
3 - the ejector (blue color)
4 - a compression helical spring that I haven't shown into the animation. The spring it is put inside the ejector, you can see the carved area into the ejector.


Basically I need to find out what is the necessary force that the spring must generate in order to make the leg roll over. I forget about the friction in the joints or with the air.


How it works:
a. The simulation starts with the spring being compressed (height=35mm) and with the ejector (1) resting on the base (2).
b. The spring is released rapidly, the ejector still stays in contact with the base (1) but the leg (2) it starting to rotate around its joint
c. Now the energy is big enough and we have a take-off The ejector (3) have a linear travel of 50mm. The spring (4) has a free height of 85mm (35+55)
d. Now the leg (2) is rotating, given the applied impulse until it falls on the right side of the base



I. This mechanism can be simulated in SW Motion? What if the leg will not have a rotational joint with the base and it will have a 3D contact instead?

I. Is best to use 3D contact between the ejector (3 - red) and the base (1 - black)?

II. How to specify that the ejector moves only 50mm linear travel and then moves solidary with the leg? For the animation I have used a distance mate that is being activated after a while (I'm not sure if it is the best way).



To sum up: can SW motion simulate the structure in the video and tell the needed force to roll it?


Thank you for reading this long post