When you compute an operating point based on input, output, or state
specifications, the Simulink^{®}
Control Design™ software indicates whether the specifications were successfully met
during the trimming process. If the trimming was unsuccessful, to determine the
specifications that could not be met, you must validate your trimmed operating
point against the original specifications.

When you compute an operating point using **Steady State Manager**,
the software creates an operating point report object and highlights any
operating point values that violate the constraints in the
specification.

For example, consider the `scdairframeTRIM`

model. Open the
model and set the speed and incidence angle parameters.

```
sys = 'scdairframeTRIM';
open_system(sys)
alpha_ini = -0.21;
v_ini = 933;
```

To open **Steady State Manager**, in the Simulink model window, select **Analysis** > **Control Design** > **Steady State Manager**.

Create a trim specification for the model. On the **Steady
State** tab, click **Trim
Specification**.

In the **spec1** document, specify which states are known
and which are at steady state.

To trim the model, on the **Specification** tab, click
**Trim**
. The software generates an operating point report and,
in the corresponding **report1** document, highlights any
constraint violations.

The optimization search could not find an operating point that satisfies the
specifications. As highlighted in **Steady State Manager**, the three
states specified to be at steady state are not. The highlighted state values
violate the specified constraints by more than the tolerance value specified
on the **Report** tab, in the **Validation
Tolerance** field. For steady-state conditions, the
**dx Minimum** and **dx Maximum**
constraints are both zero; that is, the rate of change for each state is
zero. In the trimmed operating point, the **Actual dx**
values violate these constraints.

For this model, specifying the second position state to be at steady state overconstrains the system, making a steady-state solution impossible.

To remove this steady-state constraint, update the specification. In the
**spec1** document, in the **Steady
State** column, clear the corresponding row.

On the **Specification** tab, click
**Trim**
. The software trims the model and opens a corresponding
**reports** tab.

You can also validate an existing operating point against a set of
specifications. For example, to check if the model initial conditions
satisfy the requirements in `spec1`

, first create an
operating point based on the model initial conditions. On the
**Steady State** tab, click **Operating
Point**. The software creates an operating point and opens a
corresponding **op1** document.

To validate this operating point against the specifications in
`spec1`

, on the **Operating Point**
tab, under **Validate Against**, select
`spec1`

.

The software creates an operating point report and opens a corresponding
**report3** tab.

The model initial conditions do not satisfy the operating point specifications.

When you compute an operating point using **Linear Analysis Tool**,
the software does not highlight constraint violations. Instead, you must
inspect the operating point report information for any violations.

If you trim the model from the preceding **Steady State Manager**
example using the same specifications in the **Linear Analysis
Tool**, the software creates an operating point in the **Data
Browser**, in the **Linear Analysis
Workspace**.

To check whether the operating point satisfies the specified constraints, in
the **Data Browser**, in the **Linear Analysis
Workspace**, double-click the operating point.

In the Edit dialog box, for the three steady-state specifications, the
trimmed state values in the **Actual dx** column violate
the zero **Desired dx** values.

When you compute an operating point at the command line, the `findop`

function outputs an operating point report to the Command Window by default. You can also return the operating point report as an output argument. For more information, see `findop`

. To validate your operating point against the specifications, you must check whether the operating point values satisfy the constraints.

For example, open the `scdairframeTRIM`

model and set the model parameters.

```
sys = 'scdairframeTRIM';
open_system(sys)
alpha_ini = -0.21;
v_ini = 933;
```

Create an operating point specification object, and specify which states are known and which are at steady state.

opspec = operspec(sys); opspec.States(1).Known = [1;1]; opspec.States(1).SteadyState = [0;1]; opspec.States(3).Known = [1;1]; opspec.States(3).SteadyState = [0;1]; opspec.States(2).Known = 1; opspec.States(2).SteadyState = 0; opspec.States(4).Known = 0; opspec.States(4).SteadyState = 1;

Trim the model.

op = findop(sys,opspec);

Operating point search report: --------------------------------- Operating point search report for the Model scdairframeTRIM. (Time-Varying Components Evaluated at time t=0) Could not find a solution that satisfies all constraints. Relax the constraints to find a feasible solution. States: ---------- (1.) scdairframeTRIM/Airframe Model/EOM/ Equations of Motion (Body Axes)/Position x: 0 dx: 913 x: -3.05e+03 dx: -194 (0) (2.) scdairframeTRIM/Airframe Model/EOM/ Equations of Motion (Body Axes)/Theta x: 0 dx: 0 (3.) scdairframeTRIM/Airframe Model/EOM/ Equations of Motion (Body Axes)/U,w x: 913 dx: 25.3 x: -194 dx: 273 (0) (4.) scdairframeTRIM/Airframe Model/EOM/ Equations of Motion (Body Axes)/q x: 0 dx: 31.2 (0) Inputs: ---------- (1.) scdairframeTRIM/delta u: 0 [-Inf Inf] Outputs: ---------- (1.) scdairframeTRIM/alpha y: -0.21 [-Inf Inf] (2.) scdairframeTRIM/V y: 933 [-Inf Inf] (3.) scdairframeTRIM/q y: 0 [-Inf Inf] (4.) scdairframeTRIM/az y: 263 [-Inf Inf] (5.) scdairframeTRIM/gamma y: 0.21 [-Inf Inf]

In the operating point search report, the `dx`

values for the specified steady states have zero constraints, as indicated by the `0`

value in parentheses. The optimization search did not find a steady-state operating point, since all three of these states violate the constraints.