Graduate School of Creative Science and Engineering Waseda University
博 士 論 文 概 要
Doctoral Thesis Synopsis
論 文 題 目
Thesis Theme
A Coordinated Gas Pipeline Robot Chain System Based On Wireless Relay Communication
無線リレー通信技術に基づく協調的なガス管 ロボットチェインシステムの開発
申 請 者
(Applicant Name)
Wen ZHAO
チョウ ブン
Department of Modern Mechanical Engineering, Research on Intelligent Machines
December, 2018
No. 0
Pipeline networks especially the gas pipelines need to be inspected and maintained regularly since the leakage caused by destruction such as corrosion, deformation, and cracking is fatal to the safe operation supply of gas. In recent year, various pipeline robots for pipe inspection and maintenance have been developed and promoted since they are more effective and low-cost compared with traditional destructive pipeline inspection methods. Besides, they are more precise and time-saving than conventional external non-destructive sensor network inspection technology.
In order to deal with inspection and maintenance missions safely and efficiently in the complex pipeline environment, it is important for the robots to realize the long distance real-time information interaction with external terminal and also the more intelligent operation for releasing more workload. However, current pipeline inspection robots still meet several challenges or limitations in the pipe inspection task, which can mainly be described as two domains: environmental-factors and technical-factors. The environmental-factors are that the wireless signal attenuation limits effective in-pipe communication distance of wireless robot and further affects communication quality in the pipe. This result is due to the energy loss brought by the reflection and refraction of microwaves when are transmitted through the pipeline. Besides, same problems exist in the inspection method based on robot-sensor hybrid networks, such as WSN. Wireless signals are unable to pass through the thick soil layers or underground facilities. The technical-factors include firstly, the restrictions from communication cables for the wired robots due to the unexpected environment complexities (i.e., elbows, T-junctions) within the pipe.
Secondly, the operation of robot rely heavily on manual operation with low efficiency and low precision. The failure of pipeline inspection even risk of further damage to robots and pipes may occur due to many human operation errors.
In order to deal with these factors, we have mainly done the researches on the two solutions: operation method and communication method. In the former researches on the operation method, the most current pipeline robots which are heavily dependent on manual operation are unable to realize self-navigation in pipe. Other robots are capable of self-navigation based on multi-sensors detection and calculation. However, navigation performance will be significantly affected by the performance and accuracy of these sensors. The most important is that the self-navigation mode can reduce the workload and assist the robot to pass through some environment complexities more easily, whereas manual operation can help the operator to focus more on some key parts (i.e., pipe breakage, rust) when inspecting. The robot combining self-navigation and manual operation mode are urgently needed in the current robot-based pipeline inspection technology. For communication method technology, through analysis of special environmental-factor and technical-factor before, whether wired or wireless communication methods, the robots will inevitably encounter these problems such as short communication distance, poor communication quality, etc. Therefore a new method to optimize traditional communication method has been proposed in this research.
From the above questions and solutions we have described, we set the purpose of this research is to develop a more effective, automatic pipeline inspection system which can be operated with more reliable, stable, longer distance information interaction. Based on the above analysis, two new self-navigation methods are presented
No. 1 and implemented.
Firstly, an approach of pipeline robot’s self-navigation based on feature extraction and image processing techniques are described. Besides, the fuzzy logic control (FLC) algorithm is adopted. In this method, CCD is used to detect, locate and classify the region of interest (ROI) of the LED light reflection and pipe’s dark hole in elbow or T-junction. These ROIs were considered as the input variables in such FLC system. By reasoning on several rules about input-output logic relationship, the system can output the two important variables real-time yaw angle and velocity to support robot to realize self-navigation in the pipe. Compared with conventional studies on pipeline robot’s self-navigation method, the proposed approach could be more precise and faster with fewer external sensors. However, in this method, the detection, localization and classification of ROIs rely too much on the precision of CCD. Besides, some other factors such as pipe diameter, different reflective properties on surface of pipe wall, metal rust and pipe dirt will influence the extraction and classification of ROIs. Finally, the interval classification of output variables of FLC algorithm is so intensive that require more precise motor control in real robot application. In the real robot experiment, it require further investigation on the application and implementation about such algorithm.
Secondly, we focus on another self-navigation approach based on ultrasonic detection and evaluation for elbow and T-junction of pipeline. In this robot design, we combine two operation modes together and adopt them in real pipeline environment test. The self-navigation method is based on ultrasonic evaluation and data processing from three ultrasonic sensors. The self-navigation mode can reduce the workload for operator however without manual operation we will lose some details of pipe inspection in some complex and unstructured pipeline environment. For these reasons, the combination of manual operation and self-navigation mode will increase the efficiency of inspection. Such method is also used in robot chain system (RCS) for cooperative and coordinated movement of system.
To realize the research objective, we need to investigate a reliable, stable, and long distance wireless communication method to overcome the challenges we discussed above. Finally we developed a pipeline inspection robot chain system (RCS) based on wireless relay communication (WRC) technology. The researches were carried out in the following three steps. The first is to do research on characteristics and model of wireless signal transmission in pipeline. The second is to simulate such RCS in simulation environment. This step is to verify the feasibility, robustness and stability of such system. The third is to develop a tracked pipeline robot chain system (RCS) based on wireless relay communication (WRC). Through several verification experiments, the results reveal that such system can effectively guarantee the reliable and long-distance wireless communication for pipeline inspection system.
Firstly, we started from wireless communication method to find a best solution to the problems mentioned above. For developing a wireless pipeline inspection system, it is preferable if we can know the transmission characteristics and model in pipe. Although we were sure about the wireless transmission model in the free-space, however, due to the complexity of pipe environment, the model was completely different from free-space transmission. There are multiple reflection and refraction of electromagnetic wave during transmission in the
No. 2
pipe. Through several experiments, we obtained the many transmission properties (i.e., transmission loss, (received signal strength indication (RSSI), maximum transmission distance, etc) in gas pipe. These parameters are crucial to determine which frequency or device are feasible to the further development. Besides, they are also important for the RSSI-based evaluation method for robot chain system.
Secondly, we proposed a concept of robot chain system based on wireless relay communication to overcome the communication challenges brought by the special pipeline environment mentioned previously. In order to ensure the feasibility, robustness and stability, we presented an approach of a reliable communication and localization method based on Received Signal Strength Indication (RSSI) theory for this robot chain.
Without any GPS modules in the pipe, the robots are able to measure and calculate a certain distance from the adjacent one by detecting and estimating the received wireless signal strength. Besides, we described a
“leader-follower” control method and localization and distance control of robot chain in pipe to support the RSSI-based communication. The leader robot is responsible for the task of whole pipe inspection with multi-sensors, and the follower robots act as the wireless “signal relay node” for communication. Finally, such pipe robot chain cooperate and coordinate together, so that they are able to complete the inspection successfully.
At last, we used virtual reality simulation to evaluate the performance of the proposed method. The simulation result indicated that the proposed method could realize the reliable wireless communication and localization for the robot chain system.
At last, through the above research on communication and operation methods, we proposed a prototype of a tracked robot chain system based on wireless relay communication to overcome the technical and environmental challenges as mentioned before. In this system, each robot serves as a “relay communication node”. Leakage information of pipes are transmitted through these “relay nodes”. To ensure the stability of relay communication between adjacent robots, we adopt RSSI (Received Signal Strength Indication)-based evaluation method for cooperative and coordinated movement of robot chain system in pipe. Moreover, the adoption of wireless application layer communication protocol (WALCP) increases the stable performance of such wireless relay communication. Besides, each robot in chain system is capable of self-navigation and manual operation based on ultrasonic measurement module. Finally, multiple experiments to evaluate relay communication quality, RSSI-based cooperative movement and test of RSSI and Link Quality Indication (LQI) were conducted. Results reveal that our proposed system could realize reliable, stable and long-distance relay wireless communication and basically increase the inspection range effectively with comprehensive performance.
As a conclusion, this proposed robot chain system had made a breakthrough not only in communication but also in operation method. With WALCP-based communication algorithm and RSSI-based evaluation technology, such system can realize more reliable, stable, long-distance wireless communication, which can assist the system to adapt to complicated environments of pipelines. With double operation modes, the system can release the workload of operator, reduce the risk of operation failure and finally increase the efficiency of inspection. This concept of research is not suitable for pipeline inspection robot, it also can be applied in special environments such as difficulties in using wired communication or with weak wireless signal.
No.1
早稲田大学 博士（工学） 学位申請 研究業績書
(List of research achievements for application of doctorate (Dr. of Engineering), Waseda University)
氏 名(Full Name)
Wen ZHAO
印(seal or signature )（
As of October, 2018
） 種 類 別(ByType)
題名、 発表・発行掲載誌名、 発表・発行年月、 連名者（申請者含む）
(theme, journal name, date & year of publication, name of authors inc. yourself) Patent
International Conferences
Papers (Peer Reviewed
Articles)
[1] M. Kamezaki, S. Sugano,
W. Zhao, K. Yoshida, M. Konno /亀﨑 允啓, 菅 野 重樹, 趙 聞, 吉田 健人, 今野 実, “移動体，並びに、これを用いた遠 隔操作システム及び配管内の遠隔操作システム”, 2018-100063, June.2018.
[2]
W. Zhao, M. Kamezaki, K. Yoshida, M. Konno, A. Onuki, and S. Sugano,“An Automatic Tracked Robot Chain System for Gas Pipeline Inspection and Maintenance Based on Wireless Relay Communication”, 2018 IEEE/RSJ International Conference in Intelligent Robots and Systems (IROS2018), pp.
6551-6556, Oct. 2018.
[3]
W. Zhao, M. Kamezaki, K. Yoshida, M. Konno, A. Onuki, and S. Sugano,“Modeling and Simulation of FLC-based Navigation Algorithm for Small Gas Pipeline Inspection Robot”, 2018 IEEE International Conference on Advanced Intelligent Mechatronics (AIM2018), pp. 912-917, Jul. 2018.
[4]
W. Zhao, M. Kamezaki, K. Yoshida, M. Konno, R. Toriumi, and S. Sugano,“A Reliable Communication and Localization Method for Gas Pipeline Robot Chain based on RSSI Theory”, 2017 IEEE/SICE International Symposium on System Integration (SII2017), pp. 282–287, Dec. 2017.
[5]
W. Zhao, M. Kamezaki, K. Yoshida, M. Konno, R. Toriumi, and S. Sugano,“Preliminary Measurement and Analysis of Microwave Transmission Attenuation in Small Gas Pipeline”, 2017 IEEE International Conference on Mechatronics (ICM2017), pp. 342-347, Feb. 2017.
[6]
W. Zhao, M. Kamezaki, K. Yoshida, M. Konno, R. Toriumi, and S. Sugano,“A Prototype of a Small Tracked Robot for Gas Pipeline Inspection and
Maintenance”, 2018 International Conference on Intelligent Human Systems
Integration (IHSI2018), pp. 137-142, Jan. 2018.
No.
2早稲田大学 博士（工学） 学位申請 研究業績書
(List of research achievements for application of doctorate (Dr. of Engineering), Waseda University)
種 類 別By Type
題名、 発表・発行掲載誌名、 発表・発行年月、 連名者（申請者含む）
(theme, journal name, date & year of publication, name of authors inc. yourself)
Co-Authored Local Conferences
Papers
