Dear researchers, how can can I simulate nonlinear disturbance observer for UAV on Simulink?

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UASLAB 2022-6-28

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采纳的回答： Sam Chak

I want to model this nonlinear disturbance observer -

- on Simulink, in order to estimate the disturbance. Any relevant help is well appreciated.

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Sam Chak 2022-6-28

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Hi @ALABA PHILIP OPAYEMI

As you didn't provide sufficient explanations for the problem and I don't know what it is, so I just integrated the given differential equation in the blue NDO Fcn block as usual, and this is the simplest example I can make with the disturbance

Hope it works out for you.

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Sam Chak 2022-6-30

Great to see that it works out. @ALABA PHILIP OPAYEMI

Anyhow, you should understand that any constant term that goes into the NDO (to be integrated) can be a "suspect".

And the

is just one of the prime suspect if it does not get cancelled out by your control input u.

UASLAB 2022-6-30

@Sam Chak

alright sir, thank you.

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Sam Chak 2022-9-5

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Hi @ALABA PHILIP OPAYEMI

There are two Dryden Wind Turbulence Model blocks: one is continuous and the other is discrete. Check out the links:

You can also see this example on how the disturbance model is implemented.

https://www.mathworks.com/help/aeroblks/nasa-hl-20-lifting-body-airframe.html

If you find the guidance is helpful, please consider voting 👍 the Answer. Thanks!

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Sam Chak 2022-9-6

@ALABA PHILIP OPAYEMI, Thanks for your clarification. Looks like this is beyond NDO. NDO is simply pure math, just a single line of equation. But your new questions are Engineering and Physics problems. It's not even a MATLAB/Simulink problem.

Can you find out the DCM formula for your Quadrotor?
When I say it's Physics, it's because I think we need to imagine what the Airspeed is defined according to the Aerodynamics. I presume that you are Aeronautical Engineering Guy based on the project you did above (correct me if I'm wrong). Sure this is only simulation and you cannot measure the real Airspeed. But you can definitely estimate them (via mathematical formula) from the states of your Quadrotor.

MathWorks Help Center Search results show that there are blocks in the Aerospace Blockset for you to compute and obtain the DCM. See link:

https://www.mathworks.com/help/aeroblks/axes-transformations-1.html

If you don't have the Blockset, you can write the code to compute DCM. I've checked with a lecturer in the Department of Mechanical & Aerospace Engineering. DCM is commonly taught in Flight Dynamics and Control, or Motion of Mechanical Systems.

Stay calm because the challenge is not as big as you think. Do 1 thing at at a time. I'd suggest that your put the Simulink simulation on hold. Sort out the mathematical formulas that you need to compute the Quadrotor DCM and Airspeed. If you still needs help, then ask a new question on how to put those formulas in the Simulink Block.

UASLAB 2022-9-6

Thank you @Sam Chak

...I presume that you are Aeronautical Engineering Guy...No, you are not...

I will work on the insights you have given.

Thank you.

UASLAB 2022-9-6

Dear sir @Sam Chak,

I have tried to incorporate the DCM and other necessary input parameters into the model but did not work. I am yet to understand how to implement it...

However, I have been using this model(https://www.mathworks.com/help/simulink/slref/aircraft-longitudinal-flight-control.html) below and it works; except that I do not know how to vary the parameter to get different desired wind speeds as I am yet to come accross any documentation on it.