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gfraulini17-Peridot
17-Peridot
Dec 28, 2023 8:56 PM UTC
Question

Connections attivabile

Is there a way to make a connection attivabile by relation?
In the sens of a connection (gear or motor for example) that runs under certain situations and it doesn't in some others.
Eg: if this distance is lower than X, then you don't work.

 

Thanks

7 replies

tbraxton
tbraxton22-Sapphire II
22-Sapphire II
Dec 29, 2023 1:01 PM UTC

I think what you are looking for is control of the servo or motor within mechanism mode. This is not done using part relations but provides options for conditional forcing functions applied to a design in Creo mechanism.

 

To Define a User-Defined Motor Function (ptc.com)

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gfraulini17-PeridotAuthor
17-Peridot
Dec 30, 2023 11:49 PM UTC

Hi, this assembly is in Creo 8.0.9

 

I would to control the rotation of the green component with an actuator that may operate on other component too.
So I can't use a gear, useless I have te ability to "switch on/off" the gear; in this way I can the same gray piece to operate over other green ones.
Now I work around with 3D Connection but is a mess..

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tbraxton
tbraxton22-Sapphire II
22-Sapphire II
Dec 31, 2023 2:46 AM UTC

For a mechanism, motion axis servo motors specify the position, velocity, or acceleration of a mechanism. For example, creating a servo motor at the motion axis of a Pin connection will create a rotational servo motor. Creating a servo motor at the motion axis of a Slider connection will create a translational servo motor.

 

This is exactly the motions (1: linear 2: rotational) shown in your mechanism video above.

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SweetPeasHub17-Peridot
17-Peridot
Jan 2, 2024 2:25 PM UTC

Unfortunately, unlike some other MBD codes that can turn on and off connections based on triggers, Creo does not have the functionality.

 

What might work is an alternative to the gear connection (manual implementation) using PID servo control to relate the two rotational DOFs in the similar way as a gear. The PID implementation is a bit tricky to tune because it indirectly uses the torque to control for example the ratio of speeds. In your case it is even more difficult because you also need to add the domain control such that the PID is only active when the parts have translated some amount to be together.

 

I think 3D contact might be the least messy way and it can also evaluate the case when the teeth are being synchronized. I would probably put a dummy sphere on one part, and some added cylinders on the mating part to ensure the parts ultimately slide into engagement if they happen to be out of sync. Its a bit difficult for me to portray, without doing a full model but don't feel like you have to use the exact surfaces of the part. You could even use a pattern of spheres to model a more complex 3D contact shape. A good example is when modelling the drop of a box onto a floor, the flat planes are not used, rather small spheres are placed at each corner to contact the floor.

 

Here is a reference for the PID method.

https://community.ptc.com/t5/Analysis/Can-a-PID-motor-control-be-implemented-in-CREO-mechanism/m-p/572347/highlight/true#M527

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gfraulini17-PeridotAuthor
17-Peridot
Feb 3, 2024 9:49 AM UTC

Hi SweetPearsHub, what you've posted is an old thread where I also intervened.
Now I use a workaround system because I have inserted different servo motors linked to a external files created by a curves generator. But I still must manage different curves instead of only one.
I wonder if PTC has the will of improve his Mechanism module....

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