System Identification of MIMO

Hi guys I'm working on a project of quadrotor control.

I've done the first principles modelling using SimMechanics, and now I would like to compare the plant model with a model derived from input/output data from the real life.

My question is about how to use System identification when you have more than one input and output, does I need to input random values at all inputs at the same time? Ore try to create models for each output?

Thanks in advance!

Answer 1

[Sebastian Castro]

You can perform System Identification on a MIMO system, as shown in this example.

If you already have a model in SimMechanics, however, and you just want to match parameters in that model to your data, I'd recommend using the parameter estimation capabilities in Simulink Design Optimization (if this product is available to you). Here is an example of parameter estimation for an inverted pendulum model in SimMechanics .

[Daniel Abara]

@Sebastian Castro thank you for your answer. However, OP asked if you need to give inputs to the system all at once, or if you need to do it separately (channel by channel).

I have a similar problem. I have designed a controller to stabilize a quadrotor. Now I want to identify the entire system as a whole, that is from xd,yd,zd,roll_d,pitch_d,yaw_d, to the measured x,y,z,roll,pitch,yaw. So I can use the model as an agent in a co-operative controller design. So similar to OPs question, do I obtain the data, channel by channel, or do I give setpoints such as PRBS (for example), to all the inputs at the same time, while measuring the outputs.

Thanks for the link you provided above. However, it does not answer that question but it very well explains how to manipulate the data and perform MIMO identification, thank you.

[Chandan Sinha]

@Daniel Abara I am in the same boat as you. I am doing system identification of a hexacopter platform. Do let me know how you ended up doing it for your drone. Should we give channel by channel excitation (one at a time) and obtain a transfer function (or related state space/nonlinear) model for each path from input to output?

[Branislav]

Still no answer to this question? Such an important topic, however basic answers are missing.

Answer 2

[Osama Zekry]

Hi Leonardo,

Did you find a solution for this problem? Please, provide me with any advice. Your response is much appreciated.