Algebraic loop problem in attitude control
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Hi,
I am working on the attitude control of a spacecraft with flexibles appendages, but my simulink model return an algebraic loop warning, and I think it could be the reason of the error in the control.
I can run the simulation but the quaternions, after a first moment of correct trend, start a constant oscillation (i link the picture of the trend). ![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/389763/image.jpeg)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/389763/image.jpeg)
So I reach the right quaternion value but then i start oscillating. All the suggestions are welcome.
I have already tried with a memory block or a delay block to break the loop, but the simulation can't work in this way.
I link also the equations that bring to the algebraic loop.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/389768/image.png)
Thank you for the help!
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Answers (1)
Amrtanshu Raj
on 27 Oct 2020
Hi,
You can refer to this to understand the execution order of the simulink blocks and edit your model so that you no longer get the algebric loop. In most cases simulink itself will solve the algebric loop iteratively. I would also advice you to look into your model if there is some other error which is causing the oscilations.
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