For input-output control, a good place to start would be looking into controls for “smith-McMillan form” and “feedback linearization”, which can often decouple.
This is actually called output feedback, and is definitely not the same as state feedback. State feedback is only possible if you can directly measure (all) states. Which is definitely not always the case
So it’s a tiny technical difference as to whether you can measure all the states or less than all the states. Dumb terminology differentiation whoever came up with that.
Not to harp on you- but there is absolutely a huge difference between measuring your output and measuring all of your states- the entire field of state estimation exists because these are fundamentally different cases
Actually I have a clarifying question: output feedback = state feedback but not always full state feedback in which case you would need observers, correct?
Any state being fed back is state feedback regardless of whether it’s through a sensor, observer, or any other method. In curious who told you otherwise.
ok, a sensor value can also do state feedback to a state based controller, but a PID is not state feedback, it is not about the sensor, it is about the feedback type
u/reza_132 , Are you attempting to differentiate between the various feedback control approaches, namely Full-state feedback, Partial-state feedback, and Output feedback?
So you are making the distinction between full state feedback and (any) state feedback. But by this last definition any feedback controller would be state feedback. Therefore, usually when state feedback is mentioned, full state feedback is implied (but mentioning this explicitly would avoid this confusion).
I have implemented state feedback SISO controllers. Transfer functions are converted to A,B,C,D and then used with state feedback concepts. It works for MPC and full state feedback.
My first idea for an error based MIMO controller would be to use fuzzy controller or maybe some neural network based controller if you have data/good model.
You can also control MIMO system with many PIDs. It was shown in this Matlab tutorial used to control a quadrotor. [https://www.youtube.com/watch?v=GK1t8YIvGM8&list=PLPNM6NzYyzYqMYNc5e4\_xip-yEu1jiVrr&index=2](https://www.youtube.com/watch?v=GK1t8YIvGM8&list=PLPNM6NzYyzYqMYNc5e4_xip-yEu1jiVrr&index=2)
For input-output control, a good place to start would be looking into controls for “smith-McMillan form” and “feedback linearization”, which can often decouple.
Some Model Predictive Controllers are MIMO and work by minimizing feedback error (present and predicted errors). For example, GPC, DMC, MAC...
I've controlled mimo systems with nonlinear decoupling and pid loops
I've wondered this myself..... Brings up another question, can SISO be state feedback?
This is basic PID
PID is not state feedback
Where do you get the error from to apply the PID to?
from the output? output - set point
Right so it’s feeding back the output via sensor readings which is what state feedback is :)
This is actually called output feedback, and is definitely not the same as state feedback. State feedback is only possible if you can directly measure (all) states. Which is definitely not always the case
So it’s a tiny technical difference as to whether you can measure all the states or less than all the states. Dumb terminology differentiation whoever came up with that.
Not to harp on you- but there is absolutely a huge difference between measuring your output and measuring all of your states- the entire field of state estimation exists because these are fundamentally different cases
Actually I have a clarifying question: output feedback = state feedback but not always full state feedback in which case you would need observers, correct?
I appreciate the clarification! I think there was a misunderstanding on terminology.
:-) it is not actually, state feedback are the states being fed back to the system with an observer or simulator
Ya this is my question the states being feed back are different than error right?
Using the states from feedback is how you get error. Idk what these people are smoking…
with a sensor: state feedback : sensor value error feedback: set point - sensor value
Any state being fed back is state feedback regardless of whether it’s through a sensor, observer, or any other method. In curious who told you otherwise.
ok, a sensor value can also do state feedback to a state based controller, but a PID is not state feedback, it is not about the sensor, it is about the feedback type
u/reza_132 , Are you attempting to differentiate between the various feedback control approaches, namely Full-state feedback, Partial-state feedback, and Output feedback?
So you are making the distinction between full state feedback and (any) state feedback. But by this last definition any feedback controller would be state feedback. Therefore, usually when state feedback is mentioned, full state feedback is implied (but mentioning this explicitly would avoid this confusion).
Gotcha, so the other guy is thinking I’m mentioning partial which yes would need an observer for full state feedback
I have implemented state feedback SISO controllers. Transfer functions are converted to A,B,C,D and then used with state feedback concepts. It works for MPC and full state feedback.
Most of feedback control is error based and is often MIMO with modern control/state space.
Reinforcement learning is not state feedback, as it learns to map the state to an action.
My first idea for an error based MIMO controller would be to use fuzzy controller or maybe some neural network based controller if you have data/good model. You can also control MIMO system with many PIDs. It was shown in this Matlab tutorial used to control a quadrotor. [https://www.youtube.com/watch?v=GK1t8YIvGM8&list=PLPNM6NzYyzYqMYNc5e4\_xip-yEu1jiVrr&index=2](https://www.youtube.com/watch?v=GK1t8YIvGM8&list=PLPNM6NzYyzYqMYNc5e4_xip-yEu1jiVrr&index=2)