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Polynomial Control Systems (2014)

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4.2.1 Functional Controllability Tests

Testing functional controllability.

Make sure the application is loaded.

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Here is a transfer-function object describing a system with two inputs and two outputs.

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This is its McMillan form.

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Despite the right half-plane zeros at s = +1 in both of the diagonal elements of the original transfer-function matrix, the system is both functionally controllable and left half-plane controllable.

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Here is another transfer-function object, describing a system with two inputs and three outputs.

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The corresponding state-space system is completely controllable and is also output controllable.

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However, since this system has more outputs than inputs, it is not functionally controllable.

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Here is the transpose of this system, which now has three inputs and two outputs.

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Here are all the minors of order 2.

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Since there is at least one nonzero 2 × 2 minor, this system is functionally controllable.

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Here is yet another system that is functionally controllable.

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The system has a zero at s = +1 in the McMillan form of the transfer-function model, and so it is not left half-plane controllable.

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In fact, it is not possible to set up two simultaneous high-gain feedback loops, that is, loops with a gain > 10, say, around this apparently simple multivariable system, and maintain stability (see Section 4.1.4).