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Message 1 of 36 (2,071 Views)

Help making a train go around a track

2071 Views, 35 Replies
03-14-2012 09:56 AM

I have been trying to achieve this for weeks and i really need help. I am in an engineering class and i need assistance in trying to make my train move. I have been trying to make a train that i made roll on a track. I have seen youtube videos of people who have made their train go around a track (I have the same dimensions as the people in the video through project lead the way). I have the train constrained to the track with a tangent constraint. I just need someone to instruct me (specifically) on how to make the wheels turn on the track (i know how to make the wheels turn, i just do not know how to make all the wheels turn in unison/together and how to make them actually move along the track instead of make the wheels turn in place.

Thank You so much!

Here is a picture

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Message 2 of 36 (2,054 Views)

Re: Help making a train go around a track

03-14-2012 11:53 AM in reply to: brandonherrer14

Tangent will not work (unless it was a one-piece circular track).
Create a dummy part of a surface body with tangent arc and lines.
Use Transitional Constraint for it to follow this single dummy part. (you will end up turning off the visibility of the dummy part) (I have left out a few steps for you to figure out - attach your assembly here if you get stuck.)  (you might become familiar with Transitional assembly constraint on a very simple assembly before going to your train)

If you are looking for a Dynamic Simulation Environment solution - that is much more difficult.
I had my class work up a DS solution - but it is very slow to solve the motion and we had to fudge the wheel rotation (the wheels do not actually drive the motion - only look like they do).

If you continue to participate in this discussion I will post some examples over the next few days (most students show up here - ask a question and then disappear).

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Message 3 of 36 (2,053 Views)

Re: Help making a train go around a track

03-14-2012 12:17 PM in reply to: brandonherrer14

Lot's of people have come here with this, do a search and see if any of them can help (A lot of the answers are "do your own work/you won't learn anything if someone else tells you how").

I've got an idea for going back and forth on a short straight piece, but I don't know if that can be in any way adapted for going around a curve.

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Message 4 of 36 (2,049 Views)

Re: Help making a train go around a track

03-14-2012 12:22 PM in reply to: dan_inv09

dan_inv09 wrote:

(A lot of the answers are "do your own work/you won't learn anything if someone else tells you how").

...but if you are persistant and answer questions and show progress I'm sure there are several people here that will guide you towards the solution.  Our experience is that students just want it given to them (and the assignment is due tomorrow).

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Message 5 of 36 (2,035 Views)

Re: Help making a train go around a track

03-14-2012 02:01 PM in reply to: JDMather

I just meant that it would take some digging to find the threads where there might be something useful.

My mock up is just a cylinder rolling inside an obround surface (so it might not relate at all to the train wheels) but I don't think I've got it rolling right. (And I hope I saved what I'm supposed to be working on because at 180° it just locked up.) When it was going the motion was jerky at best. I think my Rotation/Translation constraint might only be relating to a segment of my track.

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Posts: 27
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Message 6 of 36 (2,016 Views)

Re: Help making a train go around a track

03-14-2012 04:07 PM in reply to: brandonherrer14

I have put over 2 and a half weeks into this. I have spent about an average of 3-4 hours a day and 5 hours on the weekends. So, i can use all the help that i can get because i have tried; coming to this forum was my last resort. Trust me, i am a good student and i would never try and cheat, i just want to learn more because i want to be an engineer (aerospace preferably). I am desperate and i would be sooooo greatful if i get some specific instructions because i have put a lot of effort into this. (I mean this with the up-most respect).

I am open to anything you fellow engineers can suggest and i thank you so much in advance for the time and effort of you helping me out.

It really means a lot.

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Message 7 of 36 (1,976 Views)

Re: Help making a train go around a track

03-15-2012 03:36 PM in reply to: JDMather

Can you please send an example or two to me? It would really mean a lot.

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Message 8 of 36 (1,972 Views)

Re: Help making a train go around a track

03-15-2012 03:49 PM in reply to: brandonherrer14

Attach your assembly here to show what you have accomplished so far.

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Message 9 of 36 (1,971 Views)

Re: Help making a train go around a track

03-15-2012 04:05 PM in reply to: brandonherrer14

If you want to use a Transitional constraint you might want to create a single surface along the entire track (you can turn off the visibility later so it looks like it's just going around the track not a different part). Now, my cheap and dirty way was to have another part which has an angle constraint that I drive and it's constrained to something on the thing that gets pushed.

I'd have to really work at it if I were going to find a way to get it to move at a constant speed around anything but a circle (or a straight line I could do as well) and it's your homework not mine.

If you want to be really cheap, constrain the angle of the wheel (another constraint lock the outer wheel to it (if the two wheels spin on a separate axle) and the bars between the front and rear wheels moves the back ones) and use parameters to tie that angle to the angle of the pusher part, it might be close enough to get partial credit.

Ideally you would use a motion constraint to tie the wheels to the motion along the track, and the outer ones would need a different one if you really want to be fancy.

If you just work with JD he will help you, but he will not just give you anything. Post your files and he will tell you what you did wrong (everything you did wrong - and he will not move on until you fix everything no matter how insignificant you might think it is - and when he's done with you you will be a much better draftsman.)

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Posts: 27
Registered: ‎02-20-2012
Message 10 of 36 (1,957 Views)

Re: Help making a train go around a track

03-16-2012 06:34 AM in reply to: dan_inv09

I will upload my file in about an hour because my flashdrive broke and i need to get to my computer.

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