LMIs in Control/Click here to continue/LMIs in system and stability Theory/Negative Imaginary Lemma

LMIs in Control/Click here to continue/LMIs in system and stability Theory/Negative Imaginary Lemma Positive real systems are often related to systems involving energy dissipation. But the standard Positive real theory will not be helpful in establishing closed-loop stability. However transfer functions of systems with a degree more than one can be satisfied with the negative imaginary conditions for all frequency values and such systems are called "systems with negative imaginary frequency response" or "negative imaginary systems".

The System edit

Consider a square continuous time Linear Time invariant system, with the state space realization  

 

The Data edit

 

The LMI: LMI for Negative Imaginary Lemma edit

According to the Lemma, The aforementioned system is negative imaginary under either of the following equivalent necessary and sufficient conditions

  • There exists a   n,where  , such that,
  


  • There exists a   n,where  , such that,
  


Implementation edit

A link to the Matlab code for a simple implementation of this problem in the Github repository:

https://github.com/yashgvd/ygovada

Related LMIs edit

Positive Real Lemma

External Links edit


Return to Main Page: edit