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Finding an Operating Point
Finding an Operating Point
In this section...
“What Is an Operating Point?” on page 3-43
“Finding Operating Points in Physical Models” on page 3-44
What Is an Operating Point?
An operating point of a system is a dynamic configuration that satisfies design and
use requirements called operating specifications. You can express such operating
specifications as requirements on the system state x and inputs u. It is not always
possible to find a dynamic state that satisfies all operating conditions. Also, a system
might have multiple operating points satisfying the same requirements.
Operating points are essential for designing and implementing system controllers.
You can optimize a system at an operating point for performance, stability, safety, and
reliability.
The most important and common type of operating point is a steady state, where some or
all of the system dynamic variables are constant.
Using Operating Points for Linearization
An important motive for finding operating points is linearization, which determines
the system response to small disturbances at an operating point. Linearization results
influence the design of feedback controllers to govern dynamic behavior near the
operating point. A full linearization analysis requires one or more system outputs, y, in
addition to inputs.
See “Linearizing at an Operating Point” on page 3-48.
Example
A pilot flying an aircraft wants to find, for a given environment, a state of the aircraft
engine and control surfaces that produces level, constant-velocity, and constant-altitude
flight relative to the ground. The requirements of "level," "constant velocity," "constant
altitude," and "relative to the ground" constitute operating specifications. This operating
point is a steady state of the aircraft velocity, altitude, and orientation in space.
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