# High-Level Smart Decision Making of a Robot Based on Ontology in a Search and Rescue Scenario
## 2 Ontology in SAR Scenario
### The Ontology in SAR  
The term \"ontology\" derives from metaphysical concepts in the field of philosophy, and there is no unified definition [29]. In the research field of computer science, ontology represents a set of concepts, relations, attributes, and instances in the world. It can also reason about new or hidden knowledge based on known factual knowledge. Ontologies are widely used in many domains, such as information science [30; 31], medical science [32; 33], and education [8; 34]. The ontology in our research work is divided into a conceptual layer and an instance layer. The conceptual layer can be divided into an abstract layer and a specific layer. As shown in Figure 2, the conceptual layer describes the common conceptual knowledge related to the disaster rescue domain. The abstract layer includes the high-level and more abstract concepts, such as the SLAM class, object class, task class, and so on. The specific layer involves the concepts that are defined as more specific kinds, such as environment objects (e.g., furniture). The instance layer is the instantiation of conceptual layer and the relationships that exist among the instances. The relationships connect the instances with each other and make intelligent behavior possible. The ontology contains three parts: entity ontology, environment ontology, and task ontology. Task ontology describes the task knowledge related to smart decision-making of robots, such as the task decomposition and task allocation via hierarchical structure. Entity ontology is designed to portray the knowledge or concepts of entity corresponding to the robot. Finally, environment ontology gives a description of the knowledge related to the SAR scenario such as the environment map, environment objects information, and so on. As displayed in Figure 3, the paper extends the task ontology from four typical tasks, which are charge task, search task, rescue task, and recognize task. They are involved in the subsequent experiment to verify the designed algorithms. The task ontology is hierarchical seen in Figure 3. The task has subclass of the subtasks and atomic actions. Going forward, the preconditions of each task and atomic actions are defined with the data properties in Protege. Besides, the atomic actions are defined to have effects (delete and add) on the environment state. The task description structure is similar to Hierarchical Task Network (HTN). Thus, we can decompose the tasks the robot reasoned through ontology for task planning in SAR. Figure 2: The classification of different layers in ontology. When the robot performs a task for the first time, the initial representation of the task in OWL can be described as the follows. The task _RescueJack_ contains three atomic actions: _PickUpVictim_, _GetOutVictim_, and _PutDownVictim_. The time sequence is unknown. **Class**: RescueJack  
**SubClassOf:**  
SubRescueTasks  
(subAction some FreeVictim)  
and (subAction some PickUpVictim)  
and (subAction some GetOutVictim)  
and (subAction some PutDownVictim)  
Then, the robot will query and match the task ontology layer by layer according to the current initial state and reason about the final sequence of atomic actions. The sequence of atomic actions contains the time sequence of action execution and is a complete representation of high-level input tasks. A complete representation of a specific task is shown as follows, which is composed of the parent classes, the subactions, and the execution ordering constraints among subactions. When a specific task requires planning, the users can query and search to obtain the atomic actions sequence of the specific task. **Class**: RescueJack  
**SubClassOf:**  
SubRescueTasks  
(subAction some FreeVictim)  
and (subAction some PickUpVictim)  
and (subAction some GetOutVictim)  
and (subAction some PutDownVictim)  
and (orderingConstraints value RescueActions12)  
and (orderingConstraints value RescueActions13)  
Figure 3: The task ontology is shown in Protoße.