MATLAB quadcopter pid simulation

Question

I've found a Simulink file of quadcopter pid simulation. This is the image of simulink block diagram.

I have few questions about it.

When I press tune button in P or PI control block, it says plant cannot be linearlized. What does it mean and how can I fix it?
Does P and PI block derivates the input? At the image, the inputs(x,y,z position, phi, theta, psi angle) gets derivated and it goes to other fuction blocks' input. I wanted to make does P and PI blocks into PID blocks but I failed to because of this things.
How can I make those P and PI blocks into PID blocks which can be auto tuned and gives the input( ex) phi, phi_dot, phi_2dot... ) of other function blocks?

The link/embedded image of the block diagram isn't working. Also, welcome to stackoverflow! — Luna, Aug 04 '15 at 14:34
(1) There is no url in your link. (2) I don't think that just an image of a simulink diagram will be enough information to answer all your questions. (3) read [how to ask](http://stackoverflow.com/help/how-to-ask) to see how to reformulate your question and get better chances at getting a nice answer. — Hoki, Aug 04 '15 at 14:34
Please **avoid** making duplicate accounts to try and draw attention to your question: http://stackoverflow.com/questions/31814355/matlab-simulink-quadcopter-simulation - This is the exact same question but with the image. We can't mark this as duplicate as there are no answers, so I'm flagging your question. — rayryeng, Aug 04 '15 at 16:27
I might be able to answer this as I am one of the guys in the second video in https://uk.mathworks.com/academia/student-challenge/2012/ . Leaving this comment so I can come back with more time and answer ;) — Ander Biguri, Aug 05 '15 at 14:54

score 3 · Answer 1 · answered Aug 07 '15 at 14:03

You need to understand better PID control. Get some books.

The model is WAY too complicated for auto-tuning a PID. when I did it, I did the Maths, and with tons of linearization, still was very hard to tune. I recommend you put a PID block and go tuning the parameters by hand if its not working. Do the typical P->D->I parameter choosing. So start with only a P (I=0 and D=0). When you get a P that works, fix that, and do the same for D , now tuning a PD. After, do the same with I tuning a PID.
If you knew what a PID is, you'd know if a PI does derivative the input.... PID stands for Proportional Integral Derivative controller. If there is no "Derivative" , well.... it does not derivate.....
As I said in 1: Auto tuning does not always work, and if you quadcopter model is complex enough to describe it roughly, then you wont be able to do it. And that's it. If you could auto-tune that, the job "control engineer" would disappear from the world*.

So, I am afraid that yous questions don't have an answer. You need to get your hands dirty.

_{*Hint: Its not going to happen in the near future (and probably in the far future)}

1 Answers1