# Approaches and Challenges in Internet of Robotic Things
## 2 IoRT: An Overview
### IoRT Architectures
#### 2.6.4 Seven-Layer Architecture  
According to [47], IoRT has a seven-tier architecture, which breaks down the intricate problem into manageable parts to acquire a complete sense. This IoRT architecture is more realistic rather than just conceptual. Moreover, the data control layer in the IoRT architecture grips data at the edge, fog, and cloud. The seven-layer architecture is summarized below. **Network connectivity layer:** The connectivity layer, also called the network layer, performs packet forwarding, requiring virtual connections obtained from infrastructure suppliers to operate virtualization with the required environmental outline, trustworthiness, and efficiency for telecom operators. Studies have illustrated how low-cost IPTV distribution may be achieved via wide-area IP multicast, which tracks on the maximum of a trustworthy virtual network. This layer ensures accurate and consistent data transmission by implementing numerous protocols, switching and routing protocol interpretation, and networking inquiry [16]. **Edge computing layer:** This layer emphasizes the analysis, processing, and transformation of data. **Data accumulation layer:** This layer interprets mobile data as fixed data [54]. **Data abstraction layer:** This layer is aware of the many languages used to express data where the information is stored. As a result, the layer is able to handle the communication needs of the appropriate information sources. This layer allows multiagent systems entities to access information via Java calls, regardless of the true data representation language. Different application programming interfaces (APIs) plus a new component called the  
Figure 8: Evolution of IoRT architectures: three-, four-, five-, and seven-tier architectures. data access layer make up the DAL. The APIs are a set of Java functions that serve as a link between data stored in one location and the remains of the network. The data abstraction layer uses data stored in various formats to create easy and more performant applications [54]. **Collaboration and processes layer:** This layer of architecture utilizes and distributes the application information with business processes and people [1]. Each organization requires a specific architecture for the development of a particular product, which means that architectures are used as per the requirement. A detailed architectural diagram is shown in Figure 7, which represents the evolution of architecture. IoRT is made up of several components, such as temperature, motion, light, gas, accelerometer, and pressure sensors. Gateways in IoRT are devices that connect to any network and store data in cloud centers. Analytics or mobile applications analyze the data according to the needs. Several IoRT structures such as three-layer, four-layer, five-layer, and seven-layer architectures are provided to thoroughly analyze these components. Data are acquired from sensors and actuators in the perception layer of a three-layer design. Data are collected and sent to cloud servers for storage and analysis. The application layer is in charge of providing services to users. Layers are further subdivided into a five-layer design for a better understanding of IoRT features. Data are transferred from the physical layer to the network layer in this architecture. A vast volume of data is stored and subsequently analyzed by the processing layer or middleware. Data processed in the application layer are used by users in a human-readable format. The business layer is at the head of IoRT technology, managing the whole system, user policy, profit model, and applications. For a better understanding of IoRT technology, the five layers are divided into seven layers, each of which has been addressed previously. As a result, an evolution of layers occurs as each tiered design is required by the organization. In the evolution diagram, architectural layers are segregated into the next layers for a better understanding of technology [47; 48; 55; 56]. Table 5 mentions the various existing layered architectures.