The Internet has been expanding rapidly over the last several years, and today anyone can easily connect to the Internet from anywhere. This vast new group of users has come to rely on the Internet for a variety of purposes, including surfing the web, exchanging e-mail, and downloading files. Meanwhile, many companies have attempted to design new programs and applications in order to harness the power of the Internet in innovative new ways. For example, hopes of building home networking and crime prevention systems have been realized by connecting previous off-line equipment to the Internet. With these new applications, the Internet-based robot is also drawing attention.
The Internet-based robot has the same concept with the current tele-operation robot because both use the remote control. However, the Internet-based robot is operated using a public network and a web interface, while the tele-operation controls the robots using a private communication network and interface programs developed for experts. Therefore, unlike the tele-operation technology, the Internet-based robot is widely accessible to the public regardless of the user's terminal type and operating system. Then, the Internet-based system acquires the advantages in the economical network and popularity. However, it also has disadvantages in the uncertainty of data transmission and security. That is, the transmission time via the Internet varies according to the number of nodes and the network load and a large transmission time delay makes some control inputs distorted. Because of these disadvantages, the Internet-based robot has been used by the public in more restricted but focused fields like toy, entertainment, crime prevention, and guidance, while the tele-operation has usually been adopted in hazardous environments, such as space, deep sea conditions, and disaster areas. However, the disadvantages of the Internet-based robot system have been attempted to be solved by many researchers and its applicable areas are expanding.
This research is intended to develop an Internet-based robot system which is insensitive to the unpredictable Internet time delay problem in data transmission. An Internet-based mobile robot system moving in obedience to the user's direct command was developed. The developed Internet-based robot system was constructed with the robot and server are installed in the remote site, and the clients on the local site are connected to the server by the Internet. In addition, a widely available web interface that a broad range of users can access and control the robot system was constructed. For a novel compensation of the Internet time delay, the PPS (Position Prediction Simulator) is suggested and implemented to the client side of the Internet-based robot system. The user obtains the predicted position of the robot from the projective virtual scene of the PPS and operates the mobile robot using the direct control. This predicted position is based on the time at which the user's command reaches the robot system. Hence, the accurate control, such as stopping the moving robot near the target position became possible. Through the projective virtual scene using the VRML, the much faster update of the robot information in the remote site became achievable and the user can get the various viewpoints. For the verification of the proposed PPS, the tests to move the robot in a planned path and stop the moving robot near the target line were carried out. The simulation and experimental results showed that the robot mobility can be improved using the developed PPS, and this system is also insensitive to the Internet time delay in various network traffic environments.
본 연구는 인터넷에서 발생하는 불확실한 시간지연 문제에 둔감한 인터넷 로봇 시스템의 개발을 목적으로 한다. 이를 위하여 먼저 원격에 위치한 사용자가 인터넷을 통하여 전달하는 직접명령에 따라 이동하는 인터넷 주행 로봇 시스템을 개발하였다. 이와같은 인터넷 로봇 시스템에서는 데이터 전송시에 발생하는 시간 지연이 가장 중요한 문제이다. 본 연구에서는 시간지연 문제를 보상하기 위한 방안으로 위치예측시뮬레이터(PPS, Position Prediction Simulator)를 제안하였으며 이를 개발된 로봇 시스템에 적용하였다. 시뮬레이션과 실험 결과를 통하여 개발된 위치예측시뮬레이터를 이용할 경우 로봇 주행시에 발생하는 거리 오차를 줄일수 있음을 보였다.
