IntermediateTopic 61 of 101Signals, Control & Comms

State feedback and pole placement

Choose gains to place closed-loop poles.

In depth

With u=-Kx, closed-loop dynamics are A-BK; choose K (Ackermann or place) so poles are at desired locations meeting specs. Requires state measurement or estimation. Reference tracking adds feedforward gain or integral state.

Key points

  • Place poles for ζ and ω_n
  • Control effort vs speed
  • Integral augmentation
Example

Placing poles at -4±4j gives about 4% overshoot with fast settling.

Why it matters

State feedback sets the closed-loop poles directly, which gives precise control of speed and damping for multi-variable systems.

Where this is used

  • Placing the poles of a two-tank system to get a critically damped response.
  • Designing a gain matrix for a robot arm with several states.
  • Tuning a drone attitude controller by choosing pole locations.

Frequently asked questions

What is State feedback and pole placement?

Choose gains to place closed-loop poles.

Why is it important to understand state feedback and pole placement?

State feedback sets the closed-loop poles directly, which gives precise control of speed and damping for multi-variable systems.

What is pole placement?

Choosing the state feedback gains so the closed-loop matrix has the eigenvalues you specify.

Why does it need full state?

The feedback uses the state vector, so unmeasured states must be estimated with an observer or measured directly.

How is State feedback and pole placement used in practice?

Typical applications include placing the poles of a two-tank system to get a critically damped response, designing a gain matrix for a robot arm with several states and tuning a drone attitude controller by choosing pole locations.

What should I learn before State feedback and pole placement?

Study "Controllability and observability" first (topic 60 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.

What are the key points of State feedback and pole placement?

Place poles for ζ and ω_n. Control effort vs speed. Integral augmentation.

Can you give an example of State feedback and pole placement?

Placing poles at -4±4j gives about 4% overshoot with fast settling.

What comes after State feedback and pole placement?

The next topic is "Observers", which builds directly on this one.

How difficult is State feedback and pole placement?

It is classed as Intermediate in Signals, Control & Comms (topic 61 of 101). It is an intermediate topic. Work through the beginner topics in Signals, Control & Comms first.

Learning path

Want to practise? Open the interactive course for quick checks, quizzes, simulations and progress tracking.

Related topics