IntermediateTopic 48 of 101Signals, Control & Comms
Second-order system response
Defined by natural frequency and damping ratio.
In depth
G(s)=ω_n²/(s²+2ζω_n s+ω_n²): ζ<1 oscillatory, ζ=1 critically damped, ζ>1 overdamped. Overshoot M_p=e^{-πζ/√(1-ζ²)}; peak time π/ω_d; settling time 4/(ζω_n). Pole locations map directly to time-response features.
Key points
- Damped natural frequency ω_d
- Pole angle cosθ=ζ
- Dominant pole approximation
Exampleζ=0.5 gives about 16% overshoot.
What is Second-order system response?
Defined by natural frequency and damping ratio.
Why is it important to understand second-order system response?
Second-order responses describe systems with two energy stores, and their damping ratio controls overshoot and oscillation.
What do natural frequency and damping ratio tell you?
The natural frequency sets the speed of the response and the damping ratio sets how much it overshoots and oscillates.
What damping ratio is common for design?
Values around 0.7 are often used because they give a good balance of speed and overshoot.
How is Second-order system response used in practice?
Typical applications include predicting the overshoot of a robot joint with a given damping ratio, choosing damping for a suspension to limit bounce and designing a sensor mount that must not ring after a shock.
What should I learn before Second-order system response?
Study "First-order system response" first (topic 47 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.
What are the key points of Second-order system response?
Damped natural frequency ω_d. Pole angle cosθ=ζ. Dominant pole approximation.
Can you give an example of Second-order system response?
ζ=0.5 gives about 16% overshoot.
What comes after Second-order system response?
The next topic is "Time-domain specifications", which builds directly on this one.
How difficult is Second-order system response?
It is classed as Intermediate in Signals, Control & Comms (topic 48 of 101). It is an intermediate topic. Work through the beginner topics in Signals, Control & Comms first.