Lecture 9 Flashcards
If a system is stable it has
A bounded response to a bounded input - within limits not infinite
How do you introduce derivative gain
Set your control constant = kp + kd*s
Component of control signal is proportional to rate of change of the error signal
What is the characteristic equation
It is the denominator of the transfer function set equal to zero
What are the roots of the characteristic equation
The values of s that satisfy the equation ie = 0
What is s equal to
Roots of characteristic equation - has real and imaginary part
A system is critically damped when
It has two or more roots in the same location
When the roots of the characteristic equation are less -ve what happens to the response
Becomes less damped
What happens the roots of the characteristic equation Re(s) = 0
System is very lightly damped - marginally stable
When is a system unstable
When the roots have positive real parts
What should you not do before finding the characteristic equation
Cancel parts in the denominator with the numerator - can remove an unstable root
