Constraining steering in autodesk inventor
I am trying to constrain an entire steering mechanism, from the steering wheel through the universal cross joints, the shafts and the rack and pinion. What i've tried so far was constraining the steering wheel to the hole cut in the dashboard, then constrained each axis of the cross joints on the knuckle connecting the steering wheel to the steering shaft. Then as i get to the rack and pinion i no longer know what to do. I am not sure how or what constraints to make driving constraints so that when the steering wheel turns the rack moves in the appropriate direction. If anybody can point me in the right direction that would be much appreciated.
I've had a quick look, and found a couple things that just are not working correctly. I'll give you some general guidelines that I have found works for me in modeling with Inventor.
1. When leaving things unconstrained or with driven constraints you need to be aware that periodically Inventor just buggers it up, and you end up deleting the lot, and redoing exactly the same thing and it works again. I always name constraints related to moving bits. It helps to find them later when you have to start all over..
2. Work through a linkage or mechanism from one end only...in this case start at either the steering wheel or the tires, not both.
3. Apply all constraints to lock the bits that are not suppose to move. Leave only the intended degree of freedom.
4. Make sure the intended bits still move freely after adding each constraint. It is much easier to go back and find the one thing that removed teh degree of freedom than multiple.
5. Optimize your use of constraints. Use only the ones necessary. Use a single INSERT with an offset rather than an axial mate followed by an planar mate.
6. DO NOT set-up the driving constraint until all of the parts are in the assembly, and freely moving on their own.
7. Use sub-assemblies as required, but remember that flexibility needs to be enabled on each sub assembly that is moving.
8. If you are working with Inventor 2013 use sliders in a form to control the motions. This might be available in 2012 too, I don't remember. Ignore rule 6 when using a form to drive the motions.
9. Drive only 1 constraint in a linkage...allow the parts to do their job and transform the motions as required.
10. Don't create or use view representations, or positional representations until you are done playing with the driven constraints. For some reason these seem to lead the item #1 problem.
Overall you are on the right track, but I would go back and remove the constraints for the steering parts, and start over.
Assuming you are working with 2012 or newer, have a look at Steam Cylinder Assembly to see what I've done for that work in process. It won't get fully constrained until after I get pump end modeled.
Hard to say without drawings ...
One part in the Assembly must be locked (normally the first inserted), try to change the locked part with another.
I found that a constrain can be replaced with 2 or more but simply to calculate.
Activate the visibility of the degrees of freedom.
So i ran into a ton of problems trying to fix and add constraints to the steering system. It is a mess right now, but i posted the files anyways cause i am hoping an extra set of eyes can help me fix some problems. I hope i added all the necessary part files, if i didn't let me know.
Hi Eric as Fabrizio said hard to see what kind of set up you have for your .IPT's within your .IAM but if I have it in my head as you described it then it is just a standard set up for a steering column!
If you can upload the file and even screen shots we shall be able to help you with the constraints, but there is a problem I am thinking right away you are fairly new to IV and CAD? as doing the rack and pinion constraints takes a lot more knowledge to be able to do it correct...... It is not so hard but for someone to do this for there first time it is hard if you want it done correctly you will also have to have the IPT's made perfect so if you can upload the files and I have time over the weekend I shall do a full tutorial on it for you to try and follow and that way hopefully it will let you better understand constraints within IV :P
So i didn't want to waste peoples time and create an entire new thread, but i am back and stuck more then ever. This build went much better in my head. I still have not figured out my steering after deleting it and re constraining several times. But my new question is constraining the suspension. Now i didn't make the suspension, someone else in my group did so i am not sure about his dimensioning and constraining in his assembly (could be issues with the actual suspension assembly, not sure). but i am trying to lock it into my frame so only the wheel will move. Needless to say i get a ton of constraint errors. If anybody would be willing to look through it and help me figure out what is going on i would really appreciate that. Got 2 weeks to my deadline and i am banging my head. You can download the last upload from this link:
The assembly file is under Dune_Buggy/Dune_Buggy_Fame_Assembly.
This is the file before i removed everything from the tierods to the steering shaft and just trying to constrain the suspension assembly first, figure this gives the better look at what is going on.