Rack and pinion regeneration position

[daveykbelgium]

I have made an assembly of a rack and pinion. I have added a servo to the pinion, and can also drag the rack. I can run my analysis okay – all appears to be okay up until……



…..when I return to standard Pro/ENGINEER, I want the assembly to return to a controlled position – this would be done by using the regeneration command.



My question is how should I place the rack part into my assembly to be able to use a joint-axis setting that can control the regeneration position? The pinion isn’t an issue, as this uses a pin connection, and this worked until I tried to add a joint-axis setting for the rack.



I don’t think that I can use a slider connection for the rack, as the only joint axis settings here are for rotation, and this doesn’t apply. Presently I use two planar connections.





I think that Pro/MECHANISM is a very good product in concept, but I have really struggled with issues related to “controlled position” in the past too – am I the only person struggling with this, or is this functionality not required by other designers? Any rotational constraints are easy to make, but axial ones seem to be a real pain and a lot of trial and error.



PTC advised me not to use Pro/MECHANISM within top-down design methodologies too when I contacted them with regard to a similar problem – this was despite an article on their website last year giving details to the contrary. Strangely enough, the article is no longer available!



Thanks in advance



Dave

 

[Guest0527211403]

I'm sort of confused...

Why won't the slider connection work? You should be able to set planar references and then indicate a regeneration position in the Joint Axis settings. Unless I've missed something...

 

[mloew]

Dave,

You can always add a 6DOF joint (redundant) and set the joint axis settings for the regeneration position. This will have no effect on the Mechanism mode analysis. It will work similar to a snapshot.

I use Mechanisms all the time in a TDD context. We create a mechanism skeleton (assembly) to achieve this.

Best regards,

Matthew Ian Loew


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