NonlinearConstraint

NonlinearConstraint — Specify a constraint used during optimization

Script Syntax

NonlinearConstraint OptimizerName ({logical expression})

Description

The NonlinearConstraint command is used within an Optimize/EndOptimize optimization sequence to apply a linear or nonlinear constraint.

Options

Option Description

LHS

Allows you to select any single element user defined parameter, except a number, to define the constraint variable. The constraint function is of the form LHS Operator RHS

Accepted Data Types	String
Allowed Values	Spacecraft parameter, Array element, Variable, or any other single element user defined parameter, excluding numbers
Default Value	`DefaultSC.SMA`
Required	yes
Interfaces	GUI, script

Operator

logical operator used to specify the constraint function. The constraint function is of the form LHS Operator RHS

Accepted Data Types	Reference Array
Allowed Values	`>=`, `<=`, `=`
Default Value	`=`
Required	yes
Interfaces	GUI, script

OptimizerName

Specifies the solver/optimizer object used to apply a constraint.

Accepted Data Types	Reference Array
Allowed Values	Any VF13ad or fminconOptimizer object.
Default Value	DefaultSQP
Required	yes
Interfaces	GUI, script

RHS

Allows you to select any single element user defined parameter, including a number, to specify the desired value of the constraint variable. The constraint function is of the form LHS Operator RHS

Accepted Data Types	String
Allowed Values	Spacecraft parameter, Array element, Variable, or any other single element user defined parameter, including numbers
Default Value	7000
Required	yes
Interfaces	GUI, script

GUI

You use a NonlinearConstraint command, within an Optimize/EndOptimize sequence as shown below, to define an equality or inequality constraint that you want to be satisfied at the end of the optimization process.

Double click on NonlinearConstraint1 to bring up the NonlinearConstraint command dialog box, shown below.

You must provide four inputs for the NonlinearConstraint command dialog box above:

Choice of Optimizer.
Constraint Object. Click the Edit button to the right of this field to select the type of constraint object from three possible choices, Spacecraft, Variable, or Array.
Logical operator. Select one from three choices, =, <=, or >=.
Constraint Value.

Note that Inputs 2-4 define a logical expression. In the example above, we have: DefaultSC.SMA = 7000

Remarks

Number of Vary, NonlinearConstraint, and Minimize Commands Within an Optimization Sequence

An Optimization sequence must contain one or more Vary commands. Vary commands must occur before any Minimize or NonlinearConstraint commands.

Multiple NonlinearConstraint commands are allowed. There is exactly one NonlinearConstraint command for every constraint.

It is possible for an Optimize/EndOptimize optimization sequence to contain no NonlinearConstraint commands. In this case, since every optimization sequence must contain (a) one or more NonlinearConstraint commands and/or (b) a single Minimize command, the optimization sequence must contain a single Minimize command.

Command Interactions

The Minimize command is only used within an Optimize/EndOptimize Optimization sequence. See the Optimize command documentation for a complete worked example using the NonlinearConstraint command.

Optimize command	NonlinearConstraint commands can only occur within an Optimize/EndOptimize command sequence.
Vary command	Every Optimization sequence must contain at least one Vary command. Vary commands are used to define the control variables associated with an Optimization sequence.
Minimize command	A Minimize command is used within an Optimization sequence to define the objective function that will be minimized. Note that an optimization sequence is allowed to contain, at most, one Minimize command. (An Optimization sequence is not required to contain a Minimize command)

Examples

% Constrain SMA of Sat to be 7000 km, using SQP1
NonlinearConstraint SQP1( Sat.SMA = 7000 )

% Constrain SMA of Sat to be less than or equal to 7000 km,
% using SQP1
NonlinearConstraint SQP1( Sat.SMA <= 7000 )

% Constrain the SMA of Sat to be greater than or equal to 7000 km,
% using VF13ad1
NonlinearConstraint VF13ad1( Sat.SMA >= 7000 )

As mentioned above, the NonlinearConstraint command only occurs within an Optimize sequence. See the Optimize command help for complete examples showing the use of the NonlinearConstraint command.