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LMI to Find the Controllability Grammian
Being able to adjust a system in a desired manor using feedback and sensors is a very important part of control engineering. However, not all systems are able to be adjusted. This ability to be adjusted refers to the idea of a "controllable" system and motivates the necessity of determining the "controllability" of the system. Controllability refers to the ability to accurately and precisely manipulate the state of a system using inputs. Essentially if a system is controllable then it implies that there is a control law that will transfer a given initial state and transfer it to a desired final state . There are multiple ways to determine if a system is controllable, one of which is to compute the rank "controllability grammian". If the grammian is full rank, the system is controllable and a state transferring control law exists.
The System
where , , at any .
The Data
The matrices necessary for this LMI are and . must be stable for the problem to be feasible.
The LMI: LMI to Determine the Controllability Grammian
is controllable if and only if is the unique solution to
,
where is the Controllability Grammian.
Conclusion:
The LMI above finds the controllability grammian of the system . If the problem is feasible and a unique can be found, then we also will be able to say the system is controllable. The controllability grammian of the system can also be computed as: , with control law that will transfer the given initial state to a desired final state .
Implementation
This implementation requires Yalmip and Sedumi.
https://github.com/eoskowro/LMI/blob/master/Controllability_Gram_LMI.m
Related LMIs
Stabilizability LMI
Hurwitz Stability LMI
Detectability LMI
Observability Grammian LMI
External Links
A list of references documenting and validating the LMI.
LMI Methods in Optimal and Robust Control - A course on LMIs in Control by Matthew Peet.
LMI Properties and Applications in Systems, Stability, and Control Theory - A List of LMIs by Ryan Caverly and James Forbes.
LMIs in Systems and Control Theory - A downloadable book on LMIs by Stephen Boyd.
LMIs in Control Systems: Analysis, Design and Applications - by Guang-Ren Duan and Hai-Hua Yu, CRC Press, Taylor & amp; Francis Group, 2013, Section 6.1.1 and Table 6.1 pp. 166–170, 192.
A Course in Robust Control Theory: a Convex Approach, - by Geir E. Dullerud and Fernando G. Paganini, Springer, 2011, Section 2.2.3, pp. 71-73.
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