SAREF4LIFT has been specified and formalised by investigating related resources in the smart lifts domain, as reported in ETSI TR 103 546 [i.1] and ETSI TS 103 735 [i.2]. Therefore, SAREF4LIFT shall both:

- Allow the implementation of a limited set of related use cases already identified in [i.1].
- Fulfil the requirements provided in Clause 5, mainly the ontological ones that were mostly taken as input for the ontology specification.

SAREF4LIFT is an OWL-DL ontology. For embedded semantic analytics purposes, SAREF4LIFT shall be designed using the modularity principle and can thus be mainly described by a set of knowledge modules. All these SAREF4LIFT modules are fully detailed below.

### General overview

Figure 1 presents the high level view of the envisioned model of SAREF4LIFT ontology. In Figure 1, classes directly imported from SAREF ontology are in light orange, classes directly imported from other SAREF extension ontologies are in green. While, classes developed for SAREF4LIFT are in blue.

Figure 1: SAREF4LIFT overview.

Within Figure 1, as well as within all the figures that are depicted in this documentation, the following conventions are used:

- Arrows are used to represent properties between classes and to represent some RDF, RDF-S and OWL constructs, more precisely:

- Plain arrows with white triangles represent the rdfs:subClassOf relation between two classes. The origin of the arrow is the class to be declared as subclass of the class at the destination of the arrow.
- Dashed arrows between two classes indicate a local restriction in the origin class, i.e. that the object property can be instantiated between the classes in the origin and the destination of the arrow. The identifier of the object property is indicated within the arrow.

- Datatype properties are denoted by rectangles attached to the classes, in an UML-oriented way. Dashed boxes represent local restrictions in the class, i.e. datatype properties that can be applied to the class they are attached to.
- Individuals are denoted by rectangles in which the identifier is underlined.

SAREF4LIFT is an OWL-DL ontology and shall be designed using the modularity principle (see ETSI TR 103 510 [i.4]) and can thus be mainly described by the following self-contained knowledge modules:

- Systems and connections. This module defines the different systems modelled within a smart lift environment. A system is described as a component virtually isolated from the environment, whose behaviour and interactions with the environment are specifically defined. Systems can be connected to other systems. Connected systems interact in some ways. Systems can also have subsystems. Properties of subsystems somehow contribute to the properties of the supersystem.
- Devices and commands. This module defines the devices included within a smart lift. A device is defined as a tangible object designed to accomplish a particular task. In order to accomplish this task, the device performs one or more functions. The root of this branch (saref:Device) is inherited directly from the SAREF Core ontology. Also, this module defines commands supported by the defined smart lift. A command is defined as a directive that a device should support to perform a certain function. A command may act upon a state, but does not necessarily act upon a state. For example, the ON command acts upon the ON/OFF state, but the GET command does not act upon any state, it simply gives a directive to retrieve a certain value. The root of this branch (saref:Command) is inherited directly from the SAREF Core ontology.
- States and measurements. This module defines states that features of interest in a smart lift installation can be found in, and measurements that can be made about features of interest in a smart lift.
- Signals. This module describes the types of signals supported by a smart lift. Four type of signals have been identified:, car signal (s4lift:AlarmSignal), fault signal (s4lift:FaultSignal), status signal (s4lift:StatusSignal), and statistic signal (s4lift:StatisticSignal). The section on Signals provides a complete taxonomy of supported signals with respect to the ones reported in Figure 1.

Besides the four module described above, the SAREF4LIFT extension defines also two new property types (s4lift:Load and s4lift:Voltage) defining the load in the smart lift car and the electric voltage of some electric power system.

### Systems and connections

This module specializes the SAREF4SYST ontology pattern for the Smart Lift domain.

A Smart Lift system can be defined as a s4syst:System made by different components. This module defines the subcomponents that are part of Smart Lift. In particular, two subcomponents are denoted: the s4lift:SmartLiftEdgeComponent and the s4lift:SmartLiftEdgeControlUnit. The former is dedicated to the hosting of smart lift additional modules in the case that they are not hosted directly in the s4lift:SmartLiftEdgeControlUnit. An example could be the case of an additional earthquake sensor added after the lift deployment and not controlled by the s4lift:SmartLiftEdgeControlUnit. The latter is the main element of a Smart Lift installation and it is typically associated with the lift control cabinet.

A s4lift:SmartLiftInstallation corresponds to a single lift, with all its elements. Such a concept is equipped with the list of properties shown in Figure 2. Seven types of installations are considered relevant for this extension: namely s4lift:AccessibleGoodsOnlySmartLift as per EN 81-31 [2], s4lift:AccessibleGoodsOnlySmartLift as per EN 81-72 [3], s4lift:GoodsSmartLift, and s4lift:MachineRoomLessSmartLift, s4lift:PassengerAndGoodsPassengerSmartLift as per EN 81-20 [4], s4lift:SmartLiftWithoutEmergencyCallSupport, s4lift:VerticalSmartLiftingPlatform as per EN 81-41 [5]. All these concepts represent a type of smart lift that can be instantiated by the ontology.

A s4lift:SmartLiftGroup represents the correlation of multiple Smart Lifts Installation and it is supported by the introduction of a Smart Lift Group identifier common each Smart Lifts Installation belonging to the same Smart Lift Group. Such kind of installations usually presents control units connected one each other to coordinate the movement and position of the different lifts, where the common commands (e.g. the call buttons) are given to one of these control units that acts as a principal master and coordinates the other installations or is composed by peer installations that coordinates one each other.

A s4lift:SmartLiftCar represents the car of a Smart Lift. A s4lift:SmartLiftInstallation usually contains different s4lift:CarStopSpaces serving different spaces of different floors at s4lift:Smart LiftCarService. A s4lift:SmartLiftCar can connect to some s4bldg:BuildingSpace through some s4lift:SmartLiftCarService at some s4lift:DoorConnectionPoint.

A s4lift:Network is the class of communication networks. Systems can connect to other networks through a potential s4lift:NetworkAccess connection.

Figure 2: Systems and connections model.

### Devices and commands

This model specifies the list of commands that is considered relevant for the smart lift domain. Six new defined commands that are subsumed by the saref:Command concept that can be triggered, in turn, by a saref:Function as presented in Figure 3:

- s4lift:MainBoardResetCommand defines the command for resetting the main board of a smart lift;
- s4lift:SendCarToSpecificServiceCommand defines the internal command for sending the car to a specific service;
- s4lift:SetOutOfServiceCommand defines the command for putting the smart lift in out of service mode;
- s4lift:SetRealTimeModeCommand defines the command for putting the smart lift in out of service mode;
- s4lift:TestEmergencyNumberCommand defines the command for testing if the emergency number is working;
- s4lift:TestRideCommand defines the command for performing a test ride of a smart lift.

Figure 3: Devices and commands model.

### States and measurements

This module defines states that features of interest in a smart lift installation can be found in, and measurements that can be made about features of interest in a smart lift.

Figure 4: States and measurements model.

### Signals

This module describes the types of signals that can be read from a smart lift console. Figure 5 shows the taxonomy of the relevant types of signals foreseen within this extension.

It is possible to observe a set of four main types of signals:

- s4lift:AlarmSignal: this defines high priority signals used to attract the operator’s attention to important deviations or abnormal events in system operation.
- s4lift:StatisticSignal: such signals convey (s4lift:conveys) a s4lift:StatisticsMeasurement about the smart lift usage.
- s4lift:FaultSignal: these are the signals sent by the smart lift car about its overall status. This concept subsumes three further concepts grouping likewise car signal types.
- s4lift:StatusSignal: these are signals that convey (s4lift:conveys) a saref:State of a feature of interest.

Descendants of the s4lift:Signal inherit the saref:hasTimestamp, saref:isAbout, and s4lift:conveys properties defining the timestamp when the signal has been generated, the features of interest that the signal is about, and the states or measurements conveyed, respectively.

Figure 5: Signals model.