IBM SG24-7368-00 manual Mdsd and SysML

￿Constraints are properties in sub-systems (that is, blocks) named ConstraintProperty and are typed by <<constraintBlock>>. A constraint block defines an expression and the attributes that represent its parameters. SysML does not prescribe any language to represent the expressions or provide a solver for it. This setting is typically offered within the usage of a particular tool.

￿The RSW uses a set of analytical constraints to verify that the system is properly calibrated (requirement System Calibration in Figure 7-2 on page 148). Three constraints are shown in Figure 7-7:

–The constraint SensorEffectiveRange computes an operational range for the sensor, based on some of its parameters.

–Similarly, the constraint WindshieldIREffectiveRange computes an operating range for infrared sensor that can be compared with the one computed for the sensor.

–Finally the constraint SensorWindshieldRangeCompare is used to compare the above values.

Figure 7-7 Definition of constraint blocks for the Rain Sensing Wiper system

Chapter 7. MDSD and SysML 157