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Rigidly connected port error with Simscape Multibody Contact Forces Library

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Adding blocks from the Simscape Multibody Contact Forces Library to a new model gives the following error message:
"External Force and Torque External_Force_and_Torque_PlaB has its follower port rigidly connected to the world frame; it has no effect. You can configure this diagnostic in the Simscape Multibody Configuration Parameters dialog."
Madhav rijal
Madhav rijal on 17 Mar 2021
I have applied spatial connection force to sphere of the leg. I am not able to model thr ground. How do you do it. I have created a brick block and connected it to it.but Spatial Contact Force is not connected through its B port to a valid geometry. This error comes. How to solve it?

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Accepted Answer

Sebastian Castro
Sebastian Castro on 23 Jan 2018
Edited: Sebastian Castro on 7 Feb 2018
This error is due to a default setting with new Simulink models, which is incompatible with the Contact Forces Library.
To resolve this:
  1. Go to Simulation > Model Configuration Parameters
  2. In the Simscape Multibody > Diagnostics pane, change the "Rigidly constrained block" diagnostic to "warning" or "none"
For those interested the details: The Contact Forces Library blocks uses "External Force and Torque" blocks to apply contact forces/torques to both bodies in contact. If at least one of these bodies is rigidly connected to the World Frame, you will get this error based on the diagnostic setting above. This error essentially warns you that you're applying a force to a body that will not move regardless of the applied force.
- Sebastian

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More Answers (4)

Ramkumar Natarajan
Ramkumar Natarajan on 5 Sep 2020
In the newer versions of Simulink, the setting is in Modeling > Model Settings instead of Simulation > Model Configuration Parameters

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