Multivariable Control System
Multivariable control system define a system in which the variable the variable interacts strongly. This kind of system must have more than one input and more than one output. A disturbance in any input causes a change of response from at least one output.
This kind of system have as many inputs and outputs as needed to control the process. A system with an equal number of inputs and outputs is said to be square.
A disturbance in any variable can cause a change in response in any output in its signal path. Depending on the system design,these paths can be direct or indirect.
In most control system,a particular input disturbance cause one output to respond by a larger percentage than the other outputs. The response of the other output is called interaction. Interaction is often a result of system design and cannot be avoided. However the system must either correct or compensate for interaction