# Robot Delay-Tolerant Sensor Network for Overhead Transmission Line Monitoring
## 6 Conclusions  
This paper proposes a novel method of wireless monitoring system for transmission lines using RDTSN. The main conclusions are summarized as follows:  
1. RDTSN is able to act as a new type of intelligent monitoring system to automatically inspect transmission lines. Because the robot always moves along the ground wire, the inspection data can be collected by the other nodes and forwarded to CMP for analysis. In addition, all the nodes of the RDTSN are in the air, without the wireless signal blocked by trees and buildings, and with an excellent adaptability. As a small number of robots are replaced with a large number of static nodes, the availability and the economy of the monitoring systems have been improved.
2. The proposed method mainly includes two parts, the RDTSN model and the data delivery strategy. In the first part, the composition and structure of the network are introduced. Then, the characteristics of the robot motion are analyzed, and two new motion models are proposed. Finally, a new mathematical model for the network is proposed. The proposed model fully considers the characteristics of the transmission lines and robots, and a scheme is designed to balance the message delivery rate and the network energy consumption. In the next part, a new routing algorithm (DTMA) is designed. DTMA is similar to the prophet algorithm, where the social information is used to calculate the link availability probability. Then, the mathematical model is combined to update the weight of the links. Finally, the homogeneous destinations of RDTSN are ranked.
3. In simulation experiments, three experimental scenarios performed including six network targets. Experimental results show that the RDTSN can complete the effective transmission of inspection data using the proposed DTMA and other three routing protocols, which verifies the effectiveness of the proposed method. In the comparison experiment, the proposed DTMA can perform as well as the other routing protocols in most cases or even better in some respects, such as the delivery ratio and the energy consumption, which verifies the feasibility of the proposed method.  
Further research should mainly focus on the following aspects. One is that it is more difficult to set the effective thresholds of RDTSN if the change trends of network performances are not obvious. The network mathematical model should be further improved to obtain better self-adaptive ability of energy consumption. The other is that DTMA sometimes cannot achieve ideal overheads and hop count in simulations. A multi-factor analysis needs to be performed on the control of the replication and forwarding of messages. It is noteworthy that all wireless nodes use IEEE 802.11n as the communication protocol in the simulation and field experiments of this paper. Although it provides a high data rate, it has a great energy consumption. In subsequent studies, we will try to use similar IEEE 802.15.4 protocol to obtain a lower energy consumption. In addition, we are ready to use RDTSN and DTMA for real tests in the actual scenarios (the scenarios simulated in this paper).  
[PERSON] proposed and developed the research design, designed the simulation experiment, collected the experimental data, performed the data analysis, results interpretation and manuscript writing. [PERSON] assisted with developing the research design and results interpretation. [PERSON] assisted with refining the manuscript writing and coordinating the revision activities. [PERSON] and [PERSON] assisted with process of experiments.  
This work was supported by a Guangdong Robot Special Project (2015B090922007), a Foshan Technical Innovation Team Project (2015 IT100143), a National Science and Technology Major Project(2014 ZX04015021), and a State Grid Jilin Electric Power Co., Ltd. Project, China (JDK2015-21). The authors also wish to thank anonymous reviewers, each of whom provided comments that directed important improvements in the manuscript.