topic Re: Unsure how to limit movement of delta parallel robot in Inventor Forum

Unsure how to limit movement of delta parallel robot

Anonymous — Fri, 19 Oct 2018 11:50:48 GMT

Hello everyone. For a university project I have been tasked to model a cable-driven manipulator using CAD. I have made an assembly, which likely contains a lot of errors as I am relatively new to the software.

I am trying to allow the assembly to move properly as to analyse the potential workspace of the robot. I have tried to use ball joints with the cable to allow free movement, but the assembly keeps "breaking" and going all over the place even though it seems constrained properly. I have looked into using the contact solver to limit the ball joints from "going through" other materials, but the model simply becomes rigid when I turn the contact solver on. I am unsure how to properly limit the movement of the robot. Thank you for the help!

Re: Unsure how to limit movement of delta parallel robot

Cadmanto — Fri, 19 Oct 2018 12:21:03 GMT

For each component there are degrees of freedom. Depending on what kind of movement you need, the degrees of freedom will allow you to know where you are at and how much is left.

Also, when you constrain a component, if you hit the double arrows shown below, it will give you a range in which to play with.

https://knowledge.autodesk.com/support/inventor-products/getting-started/caas/screencast/Main/Details/36a6df06-2e06-40f4-80a8-10530985235c.html

Oh, and as far as the so called errors you claim to have? At least you have not engaged the design doctor.

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Re: Unsure how to limit movement of delta parallel robot

TheCADWhisperer — Fri, 19 Oct 2018 12:15:32 GMT

@Anonymous wrote:
1. For a university project I have been tasked ...,

2. ...which likely contains a lot of errors as I am relatively new to the software.

3. I am trying to allow the assembly to move properly as to analyze the potential workspace of the robot.

1. Did your instructor give you instruction on how to model parts in Inventor?

2. Are you able to identify errors? If not, can you Attach your part files here?

3. Have you been given instruction on Environments>Dynamic Simulation tools within Inventor?

Can you Attach your assembly here?

Re: Unsure how to limit movement of delta parallel robot

Anonymous — Fri, 19 Oct 2018 12:21:50 GMT

Thanks for the replies. My Mentor has not used Inventor before so I'm somewhat on my own here. I have used the limits section in the constraints menu but haven't had much success with it. I'm not 100% on how to identify errors, but the model can move pretty freely and doesn't produce errors when doing so, so I assume its alright for now. I have attached my assembly below. The main problem is with the ball/sphere joint. The "socket" is turning 360 degrees around the ball and going through the top cable (as can be seen in the screenshot). The joints menu does not allow me to set limits for these parts for some reason. I want to make it only so the ball join can rotate around one half of the pin (outer side) so that it does not collide with the rest of the assembly which should allow me to see how far the end effector can be pulled from side to side and give me the foundation of being able to analyse the workspace. I cannot do this right now, as it can be pulled all the way to the side, and then the assembly jumps all over the place and deforms. I am fairly new to the limits and constraints in the software. Hopefully you can open the assembly to get a better idea of what I mean. Thank you!

Re: Unsure how to limit movement of delta parallel robot

TheCADWhisperer — Fri, 19 Oct 2018 12:31:29 GMT

@Anonymous wrote:
I have attached my assembly below.

An Inventor assembly (just like a real world assembly) must include parts (*.ipt files).

Right click on the folder that contains all of your part files (*.ipt) and assembly file(s) (*.iam) and select Send to Compressed (zipped) Folder.

Attach the resulting *.zip file here that contains all of your parts for your assembly.

Re: Unsure how to limit movement of delta parallel robot

Anonymous — Fri, 19 Oct 2018 12:31:53 GMT

My bad. Should work now!

Re: Unsure how to limit movement of delta parallel robot

mcgyvr — Fri, 19 Oct 2018 12:41:47 GMT

Besides the comments already an assembly should have all the same constraints as in real life... Do that and the movements should match real life..

Re: Unsure how to limit movement of delta parallel robot

TheCADWhisperer — Fri, 19 Oct 2018 12:55:34 GMT

First thing I notice is that Sketch1 is not fully defined and has numerous redundant dimensions.

We will have to start over from the, well, from the start.

Back in a bit.

Do you have a link to an existing mechanism that you are attempting to replicate?

Re: Unsure how to limit movement of delta parallel robot

Anonymous — Fri, 19 Oct 2018 13:28:44 GMT

I think ive jumped in at the deep end, there are some basics that I am missing unfortunately.

I am attempting to create a joint similar to this. There arent many cable manipulators around as they are a fairly new thing in terms of the project im doing. I hope this picture is sufficient! Thank you.