help!!tank motion simulation

[Guest]

i am a sw beginner...i've got two questions:


1) for a car motion simulation, which part should be defined as ground part since the whole car is moving?


2) how to define the motion of a track? it does not make sense to attach it to a wheel.

many many thanks

 

[splinedesigns]

Here is a great site where you can learn some of the advance techniques:

http://www.mikejwilson.com/solidworks/solidworks_files.htm

Best regards,
Gary


Edited by: splinedesigns

 

[Guest]

yeah, thank you, Gary. I have been to that web site but am still comfused about the track's motion.....hope i can figure it out soon...

cheers

 

[Angstboy]

I was a tank mechanic in the US Army at one point in my life. Think of the track on a tank as nothing more than a gigantic CHAIN DRIVE.


Let me try to set up a picture for you to visualize. M48/M60 series tank, other tanks operate in a similar fashion. You are looking at the side of the tank oriented so that the front of the tank is to your left, the rear to your right. You have ONE DRIVE SPROCKET providing power to the chain, this is located in the upper right corner coming directly out of the engine. Rotation is counter clock wise to make the tank go forward. The track moves horizontally right to left along the top of a set of idler rollers. If you looked at the track in cross section, it lookes like the letter T because there is a vertical piece sticking down and riding in a groove between the sets ofinner and outer rollers to keep it fromskewing.


Whenthe track reaches the front of the tank, it encounters another sprocket - this one is an idler not a driving sprocket and thetrack wraps around it from the 12 oclock toabout the 7 or 8 oclock position - then proceeds down and to the right to the bottom sets of idlers. These idlers, unlike the ones across the top which are fixed in place, are allowed toflex somewhat to accomodate uneventerrain.There are several different types of suspension systems inuse depending on what tank you are trying to model. The track proceedsfrom left to right until it reaches the end of the bottom idlers. Then it bends upward fromleft to right until it engages the drive sprocket again.


The track on the other side just functions in mirror image. A tank turns by controlling the speed that each separate track moves. Slow down one and the other side overtakes and turns toward the slower side.


I should clarify that the sprockets are actually double sprockets. The actual "links" that engage the sprockets are along the OUTSIDE edges (inner and outer) of the track. In between are the track pads, massive blocks of metal and rubber not unlike giant versions of some flexible metal watchbands.Put all the parts together, maybe 100 or more individualtrack pads plus all the links and related parts and you have ONE track - and thatcan weigh about 2 tons.


I hope this clears it up to some degree. There really is no mystery, it is just a big CHAIN like you would have on a bicycle and if you can understand that then it follows rather simply.

Cheers....

Edited by: Angstboy

 

[Rimma]

Hi


If everybody can build this moving, please send me, I need this too. Thanks. I will be <A title="LingvoUniversal (Ru-En)">grateful</A>.

 

[Angstboy]

Excuse me for one moment.... I explained how the track on a tank works to move it forward, how it functions to allow the tank toturn, and how the track stays on. If there is more explanation for that required, I will be happy to provide it.


As for the rest...have you ever heard of something called GOOGLE?You type in the website www.google.com andonce you get there you type in CHAIN SOLIDWORKS TANK and I think you will be a bit suprised at all the astounding things that come up once you start checking out the links. In IE7, this is only the third item from the top of the page that showed up on mine...


VexCAD






Also includes a model of the Chain Link which can be used to create large Chain assemblies. STEP

 

[Guest]

Wow, thank you, Angstboy.

Let me see what i can find ....


Cheers....

 

[Guest]

still a problem, still working on it...

 

[Angstboy]

What is it specifically that you are hung up on? Here is a Wikipedia article on how tracked tanks work.


http://en.wikipedia.org/wiki/Caterpillar_track


My earlierdescription applied to the M60 series of tank which I was a mechanic on; there is a good picture of that tank and it's track on the above link. It is even in the correct orientation to match my description. I said there was a second "sprocket" on the top left position when in fact it is an idler wheel - frankly, it should have been an idlersprocket from a mechanic's point of view (lol).There would be a lot fewer skewed tracks.In the shadows of the opposite side's track you can see the shape of the T forks sticking up that I described that keep the track from skewing - most of the time anyway. Bad drivers can always manage to 'throw' a track completely off with disasterous results and several hours of repair time (usually up to one's knees in mud and in the pouring rain). But I digress...


By just using Google as I mentioned and changing the search terms a little I came up with a few more links that show the principles I think quite well. For instance:


http://home.btconnect.com/british_tanker/hetzer-tracks.htm


At the above link, the chap decided to build a 1/6 scale radio controlled model tank and he detailed in photos every step in building the components of the tank tread and mechanism. He also gives excellent links to sites dealing with radio controlled model tanks that also are quite informative on the whole regarding principles.


This is part of what I meant by the thought process involved in taking that next step - "what do I do next, where do I go from here to get to my goal?". In the real world, you are presented with problems that are not in any textbook. We have a motto in our engineering shop : "The difficult we do immediately; the impossible just takes a little longer". You have to take what seems to be a problem with no handholds for you to grip and break it into more manageable chunks that you can handle. In this case, for example - how do I model a tank track? Perhaps by looking at a model tank.


And if you go to this link and watch the animation I think you will be pleasantly suprised. It took me less than 5 minutes to find it with a search on Google. One caveat - the animation IS NOT in Solidworks compatible format I am afraid. But it shows one solution. With those predrawn parts I led you to before, you can create the chain and then you just have to animate it like this fellow did.


http://xpresso24.com/index.php?lang=en&sel=content/downl oad_item&id=4


ALSO...one of my favorite personal slogans is 'open mind for a different view'...DO NOT feel constrained or overwhelmed as I am sure you must by now by the sheer undertaking of modeling the motion of a tank's tread. THERE IS MORE THAN ONE CORRECT SOLUTION.You are modeling a tank tread SYSTEM as a motion study, am I correct? So why are you automatically assuming you are modellingTWO tracks or even a TANK for that matter? Go to this link and you will see a MOTORCYCLE type vehicle with a tank tread. You could model this and you would only be modeling ONE tread - much simplier and half the work, amI correct?


[url]http://www.popsci.com/popsci/whatsnew/5fa21e6759a4c010vgnvcm 1000004eecbccdrcrd.html[/url]


For heaven's sake - THINK, man! Look at things from more than the obvious angles.

Edited by: Angstboy

 

[Guest]

Thx. BACK from the long holiday,lol, again work on the track. I had just been to the exact wikipedia web site before I read ur reply. It is just because that web site has given me a more specificinformation on tracks, therefore, i decide to propose my question more properly ---- I am going to start a new topic, 'cause I am NOT building a tank, I am just working on some tracked model, and I think it is with the Kegresse track set, which is made of rubber.


sorry, but i am still confused...

pls react to my new topic...