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.1]) and can thus be mainly described by the following self-contained knowledge modules:

- Command. This module describes the type of 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.
- Device. 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.
- System. 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.
- Signal. This module describes the types of signals supported by a smart lift. Four type of signals have been identified: bidirectional communication system signal (s4lift:BCSSignal), car signal (s4lift:CarSignal), power supply signal (s4lift:PowerSupplySignal), 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.

Beside the four module described above, the SAREF4LIFT extension defines also:

- a new property (s4lift:Load) defining the amount of electricity on the grid at any given time.
- the concept s4lift:Network providing a conceptualization of the type of network with which the smart lift is equipped for communicating information.

### Command

This model specifies the list of commands that we considered relevant for the smart lift domain. We defined seven new commands that are subsumed by the saref:Command concept that can be triggered, in turn, by a saref:Function as presented in Figure 2:

- s4lift:BoardResetCommand defines the command for resetting the board of a smart lift;
- s4lift:CallCarToSpecificFloorCommand defines the internal command for calling the car of the smart lift to a specific floor;
- s4lift:SendCarToSpecificFloorCommand defines the internal command for sending the car to a specific floor;
- 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 2: Command model.

### Device

A Smart Lift system can be defined as a saref:Device made by different components. This module defines the subcomponents that are part of Smart Lift. In particular, we denoted two subcomponents: 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. Both concepts are subsumed by the s4syst:System concept that, in turn, it subsumes the s4lift:SmartLiftInstallation that corresponds to a single lift, with all its elements. Such a concept is equipped with the list of properties shown in Figure 3.

Finally, the s4lift:SmartLiftGroup, subsumed by the saref:FeatureOfInterest concept, 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.

Figure 3: Device model.

### System

This module expands the Device module by specifying two aspects.

First, the s4lift:SmartLiftInstallation concept subsumes four type of installations considered relevant for this extension, namely s4lift:SmartLiftPlatform, s4lift:GoodsSmartLift, s4lift:GoodsOnlySmartLift, and s4lift:FiremanLift. All these concepts represents a type of smart lift that can be instantiated by the ontology.

Second, the relationship between a s4lift:SmartLiftInstallation entity and the saref:Time one. Indeed, three object properties have been defined modelling both the opening and closing time of the smart lift (s4lift:hasDoorOpenTime and s4lift:hasDoorCloseTime respectively) and the total usage time of the smart lift described by the object property s4lift:hasTraveledTime.

Figure 4: System model.

### Signal

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:BCSSignal: this type of signals relates to bidirectional signals where the communication works from the smart lift to an external console service and vice-versa. Here, it is possible to find network and test signals (i.e. s4lift:NetworkCoverage, s4lift:NetworkQualityBER, s4lift:NetworkQualityRSSI, s4lift:RegisteredNetworkOperator, s4lift:TimeOfConfirmationOfLastPeriodicTest72hAttempt, and s4lift:TimeOfLastPeriodicTest72hAttempt).
- s4lift:PowerSupplySignal: these are the signals provided by a smart lift concerning the power supply status. Here, two signals are foreseen, i.e. s4lift:EmergencyPowerSupplySignal and s4lift:StandardEmergencyPowerSupplySignal.
- s4lift:StatisticSignal: such signals refer to the collection of statistics about smart lift usage. Relevant type of signals detected are s4lift:CallsPerService, s4lift:DownwardsTravels, s4lift:UpwardsTravels, s4lift:NumberOfCalls, s4lift:NumberOfFaults, s4lift:TotalFloorsCovered, s4lift:TotalResetSequence, s4lift:TotalReverseDirection, s4lift:TotalTimeOpened.
- s4lift:CarSignal: 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:FaultSignal, defining the type of faults that can affect a smart lift car;
- s4lift:PositionSignal, defining the position where the smart lift car is; and,
- s4lift:StatusSignal, subsuming a list of status information that can be send by the smart lift car.

All descendants of the s4lift:Signal inherit the saref:hasTimestamp and saref:hasValue properties defining the timestamp when the signal has been generated and its value, respectively.

Then, the s4lift:PowerSupplySignal concept is associated with its power supply value through the s4lift:hasPowerSupplyValue property; while the s4lift:PositionSignal is associated with the corresponding position value through the s4lift:hasPositionValue property.

Figure 5: Signal model.