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How can i add a Common Gear Constraint to my simscape imported CAD?

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Santiago Gomez
Santiago Gomez on 19 Aug 2021
Answered: Steve Miller on 12 Sep 2021
Hi, well i have the following CAD that is part of a simple planetary gear
Since simscape multibody link does not support the gear mates i remove it from the CAD and export it successfully, but in Simscape i run into the following problem
As you can see the "planet" gear is going through the solar gear, that is why i require a Common Gear Constraint block between both gears, but to be honest i don't know where to put it in this diagram that simscape generated:
I tried putting it between the Fs of Revolute1 and Revolute2
but it generates the following error
=== Simulation (Elapsed: 0.455 sec) ===
Error:['Ensamblajesinbrazonirela']: The following errors were found in the model Ensamblajesinbrazonirela.
Caused by:
['Ensamblajesinbrazonirela']: Common Gear Constraint 'Ensamblajesinbrazonirela/Common Gear Constraint' has base and follower ports that are rigidly connected. You can configure this diagnostic in the Simscape Multibody Configuration Parameters dialog.
['Ensamblajesinbrazonirela/Solver Configuration']: *** Model not assembled: position violation *** Resolve this issue in order to simulate the model.
when i dissable the option it names about "Rigidly constrained block" in model settings > simscape Multibody>Diagnostics>Rigidly constrained block >none the following error shows up
=== Simulation (Elapsed: 0.358 sec) ===
Error:['Ensamblajesinbrazonirela']: The following errors were found in the model Ensamblajesinbrazonirela.
Caused by:
['Ensamblajesinbrazonirela/Solver Configuration']: *** Model not assembled: position violation *** Resolve this issue in order to simulate the model.
i tried to solve it by changing the Solver Configuration consistency tolerance to 1, insted of 1e-9 that is by deffault, but then the planet gear goes through the solar gear, again.
The example given by my teacher was just a simple pendulum made in CAD an imported to have its position controlled, without any gear mates or "complex" relations. Help me please.
*Later i need to input a torque in the solar gear in order to control it, but i think i got that part of the explanation.
**This is not my native language i am sorry if i committed some sort of grammar / traduction mistake.

Answers (1)

Steve Miller
Steve Miller on 12 Sep 2021
You are on the right track. To fix your model, you will need to
  1. Adjust the connections of the gear constraint - they need to be attached to the frames that can rotate, so the other side of the revolute joints
  2. Verify that the frames of puente_1_RIGID are properly positioned
The documentation for the Common Gear Constraint block has images that help you understand how to connect this block.
There are also many examples of gears in the Simscape Multibody Parts Library.
--Steve

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