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Problem while simulating control surfaces of an aircraft in simulink (Code Attached)

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Siddhant Panigrahi
Siddhant Panigrahi on 11 Nov 2020
Answered: Mohith Kulkarni on 9 Dec 2020
I am trying to simulate the control surface (suppose an elevator using the following blockest. I have the elevator block providing me with Cl Cd and Cm ( lift , drag and pitching coeffiecients) which will be multiplied with 0.5 * p * v* v *S to give the forces. As lift is along negative z and drag along negative x multiplied it with -1. But whenever I am running the simulation its showing the error.
  • Derivative of state '1' in block 'controlsurface_trial2/3DOF (Body Axes)/q' at time 0.0 is not finite. The simulation will be stopped. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances) as shown in the figure below:
The code is also attached . For your help ...can you pleas ehelp me out ....stuck in middle of some project for a very long time. Thanks in advance !

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Answers (1)

Mohith Kulkarni
Mohith Kulkarni on 9 Dec 2020
If there is a division by 0 or may be trigonometric infinity solutions. Here 'NaN' is the breakpoint.
To solve these type of errors, you can go try the following steps:
Use the Simulink debugger (in a model window, Simulation > debug > debug model) to identify where is the breakpoint (Inf or NaN) originates. ( Details are here: http://www.mathworks.com/help/simulink/ug/starting-the-simulink-debugger.html )
OR
Use the unit delay block / memory block.
OR
Try reducing fixed step size.
You can refer to the following link for answer by the MathWorks Support Team

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