Requirement Class: Physical System Requirements Class

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7.7 Requirement Class: Physical System Requirements Class

http:www.opengis.netspecsensorml2.0reqmodelphysical-system Target Type Derived Encodings and Schema Dependency http:www.opengis.netspecsensorml2.0reqphysical-component A physical system is used to model a hardware device as an aggregate process made of one or more components and whose location in the real world is known and of importance. Requirement http:www.opengis.netspecsensorml2.0reqmodelphysical-systempackage-fully-implemented Req 33. A schema or encoding definition supporting physical systems shall correctly implement all UML classes defined in the “PhysicalSystem” package described in this section. Sensor and actuator systems e.g. machines and robots are typically physical systems that perform a particular feat through the coordinated actions of both physical and non- physical sub-processes. Even though a sensor system’s overall application is to sense something in the environment, the system itself can consist of sensing components e.g. detectors and sensing subsystems, action e.g. actuators and robotic subsystems, and computational components. Requirement http:www.opengis.netspecsensorml2.0reqmodelphysical-systemdefinition Example: A weather station is an example of physical system that is composed of several sensors thermometer, barometer, wind sensor, etc. and other computational process such as an algorithm to compute wind chill. All these components can be described in SensorML and grouped in a PhysicalComponent description representing the station as a whole. A hand-held digital camera can also be modeled as a physical system with an overall task of sensing radiance in a scene and generating an image. However, the camera is an aggregate of various sub-processes, each of which can be physical or non-physical, and can be sensing, acting, or computational. For example, a light detector outputs a measure of brightness, which serves as the input of a computational process which outputs a signal that provides input into an actuator that controls the opening or closing of the iris. The final iris size is sensed by another detector which inputs that value into a process that encodes that value into an EXIF format that accompanies the image, which is generated by a entirely different subsystem of the camera. SensorML OGC 12-000 Copyright © 2014 Open Geospatial Consortium 63 Req 34. A process shall be modeled as a “Physical System” if it provides a processing function with well‐defined inputs and outputs, if the device description is further divided into subprocess components, and if knowledge of its physical location is of importance. The model for PhysicalSystem, as shown in Fig. 7.18, is derived from AbstractPhysicalProcess, and adds the components and connections properties that have been described in the non-physical counterpart, AggregateProcess Clause 7.4. Figure 7.18 – Model for Physical Processing System Copyright © 2014 Open Geospatial Consortium 64 Requirement http:www.opengis.netspecsensorml2.0reqmodelphysical-systemdependency-core Req 35. A schema or encoding passing the “Physical System” model conformance test class shall first pass the “Physical Component” conformance test class. SensorML OGC 12-000 Copyright © 2014 Open Geospatial Consortium 65

7.8 Requirements Class: Processes with Advanced Data Types Requirements Class