What Is an Operating Point?

An操作点of a dynamic system defines the states and root-level input signals of the model at a specific time. For example, in a car engine model, variables such as engine speed, throttle angle, engine temperature, and surrounding atmospheric conditions typically describe the operating point.

The following Simulink^®model has an operating point that consists of two variables:

下面的表总结了signal values for the model at this operating point.

The following block diagram shows how the model input and the initial state of theIntegratorblock propagate through the model during simulation.

If your model initial states and inputs already represent the desired steady-state operating conditions, you can use this operating point for linearization or control design.

What Is a Steady-State Operating Point?

Asteady-state operating pointof a model, also called an equilibrium ortrimcondition, includes state variables that do not change with time.

A model can have several steady-state operating points. For example, a hanging damped pendulum has two steady-state operating points at which the pendulum position does not change with time. Astable steady-state operating pointoccurs when a pendulum hangs straight down. When the pendulum position deviates slightly, the pendulum always returns to equilibrium. In other words, small changes in the operating point do not cause the system to leave the region of good approximation around the equilibrium value.

Anunstable steady-state operating pointoccurs when a pendulum points upward. As long as the pendulum pointsexactlyupward, it remains in equilibrium. However, when the pendulum deviates slightly from this position, it swings downward and the operating point leaves the region around the equilibrium value.

When using optimization search to compute operating points for nonlinear systems, your initial guesses for the states and input levels must be near the desired operating point to ensure convergence.

When linearizing a model with multiple steady-state operating points, it is important to have the right operating point. For example, linearizing a pendulum model around the stable steady-state operating point produces a stable linear model, whereas linearizing around the unstable steady-state operating point produces an unstable linear model.

金宝appModel States Included in Operating Point Object

InSimulink Control Design™software, an operating point for a Simulink model is represented by an operating point (operpoint) object. The object stores the tunable model states and their values, along with other data about the operating point. The states of blocks that have internal representation, such asBacklash,内存, and Stateflow^®blocks, are excluded.

States that are excluded from the operating point object cannot be used in trimming computations. These states cannot be captured withoperspecoroperpoint, or written withinitopspec. Such states are also excluded from operating point displays or computations usingModel Linearizer. The following table summarizes which states are included and which are excluded from the operating point object.