# Autonomous Navigation Framework for Intelligent Robots Based on a Semantic Environment Modeling
## 3 TOSM-Based Autonomous Navigation Framework
### Semantic Modeling Framework
#### 3.1.1 TOSM-Based Environment Modeling
For example, \"B _isNextTo_ A\" can be inferred from \"A _isNextTo_ B\", because _isNextTo_ is symmetric. In case of _isInsideOf_, \begin{table}
\begin{tabular}{c c c} \hline \hline  & & AutomaticDoor \\  & & HingedDoor \\ \cline{2-3}  & & ElevendorDoor \\ \cline{2-3}  & & Sign & GuideSign \\  & & SafetySign \\ \cline{2-3}  & & & VendingMachine \\ \cline{2-3}  & & Device & WaterPurifier \\ \cline{2-3}  & & Furniture & Table \\ \cline{2-3}  & & & Chair \\ \cline{2-3}
**Environmental** & & Person & Occupant \\ \cline{2-3}
**Element** & & Person & Pedestrian \\ \cline{2-3}  & & & Driver \\ \hline  & & & Corridor \\ \cline{2-3}  & & & Doorway \\ \cline{2-3}  & & & Room \\ \cline{2-3}  & & IndoorPlace & Elevator \\ \cline{2-3}  & & & Staircase \\ \cline{2-3}  & & & Floor \\ \cline{2-3}  & & & Cafe \\ \cline{2-3}  & & & Building \\ \cline{2-3}  & & OutdoorPlace & Road \\ \cline{2-3}  & & & Sidewalk \\ \cline{2-3} \cline{2-3}  & & Robot & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Classes. the property is transitive because we can realize \"A _isInsideOf_ C\" using \"A _isInsideOf_ B\" and \"B _isInsideOf_ C\". We divide relations between objects, places, and robots into _spatialRelation_ and _robotRelation_. _SpatialRelation_ means the spatial relations between objects and places that constitute an environment. In particular, the properties, where _Object_ specifies both domains and ranges, express relative position relations between objects within places. The properties can be used by robots to infer the relations between objects. Robots can also use a database which consists of _isInsideOf_ and _isConnectedTo_ to understand the environment similarly the way a human does. We explain the _spatialRelation_ in detail with an example in Section 3.1.2. _robotRelation_ is used to define the properties that are determined by the robot's current state. When the robot is in operation, it uses _isLookingAt_ and _isLocatedAt_ properties to comprehend the current state in real-time by associating it with objects and space stored in the database. We explain the _robotRelation_ exactly in Section 3.2  
We use datatype properties to define the TOSM of environmental elements; in the OWL, data properties are relations between instances of classes and RDF literals or XML Schema datatypes. The datatype property hierarchy, similar to object property hierarchy, represents the subproperty relations between datatype properties. Additionally, classes determine domains of the datatype properties, and datatypes determine ranges. Table 3 lists definitions of the symbolic, explicit, and implicit model for _Object_. The symbolic model consists of _name_ and _ID_ to symbolize individuals of _Object_. For the sake of clarity, we describe ranges of _pose_, _velocity_, _size_, and _color_ in the explicit model as above. The ranges of these properties are defined as an array of the datatype (e.g., float array) in the database. _isKeyObject_ in the implicit model is utilized to represent crucial objects used for localization and place recognition. Furthermore, the properties, whose domains are the subclasses of _Object_, are used to define a more specific model of each subclass. In the case of _Door_, _isOpen_ means whether it is open or not, and _canBeOpen_ means whether it can be opened if it is closed. Robots can use this information when planning and performing tasks. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Object Property Hierarchy** & **Domains** & **Ranges** & **Characteristics** \\ \hline \multirow{6}{*}{spatialRelation} & isInFrontOf & Object & Object & \\  & isNextTo & Object & Object & symmetric \\  & isAboveOf & Object & Object & \\  & isBehindOf & Object & Object & \\  & isOn & Object & Object & \\  & isInsideOf & Object or Place & Place & transitive \\  & isConnectedTo & Place & Place & symmetric \\ \hline \multirow{2}{*}{robotRelation} & isLookingAt & Robot & Object or Place & \\  & isLocatedAt & Robot & Place & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Object properties.