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ROBOTICS INTERNET TELE-LAB: PROGRAMMING USING MOBILE DEVICES R. Marin1; L. Nomdedeu2; R. Wirz3; P. J. Sanz4 Robotic Intelligent Department, Jaume I University. Castellon. Spain. ABSTRACT The present paper describes the architecture of an Internet Tele-Laboratory that allows students and researchers to program remotely several heterogeneous robots in a synchronized manner. The paper focuses on how this remote programming enabled the design of an external user interface running on Mobile devices, that has the particularity of providing predictive 3D virtual and augmented reality capabilities to the robot operator. Keywords Tele-Manipulation, Tele-Control, Wireless, Mobil Devices.
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Introduction
There is not much work done on controlling robots remotelly by using mobile devices as user interface. An interesting one has been performed at “L'Ecole Polytechnique Fédérale de Lausanne” and is known as “Advanced teleoperation interfaces”. This work enables the operator to teleoperate a mobile robot with a camera on top using a single PDA as input [1]. Moveover, at the “Intelligent Robotics Laboratory” in the Vanderbilt University several related works have as well been performed [2, 3, 4]. The PDA is used to bring the real camera input to the user and to transmit the user interactions to a mobile robot. However, none of this Works enables the user to enhance the human-robot interaction by using a 3D predictive display, alternative tested within this paper. The second type of experiments uses a PDA as central processing unit of a single robot, and then acts as Internet Server to control the servo-motors and radiocontrol of the robot [5].
2. System Architecture
Figure 1: Multiple ways of Interaction between the User and the Tele-Lab In figure 1 we can appreciate the multiples ways that are allowed to an operator to control a robot. This paper focuses on the particular situation of an operator using a PDA or mobile phone as user interface. 1
[email protected] [email protected] 3
[email protected] 4
[email protected] 2
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The technology used for designing the user interface is called MIDP (Mobile Information Device Profile). This client developed in MIDP has the particularity of being very Light-weight and it enables having access to almost every feature of the remote tele-laboratory. VOICE COMMANDS
NATURAL LANGUAGE RECOGNITION OBJECT RECOGNITION
LAB EXERCICES
JAVA3D VIRTUAL& AUGMENTED REALITY
ROBOTICS TUTORIAL T
COMPUTER VISION
EXPERIMENTS SERVER
SPEECH RECOGNIZER & SINTHESIZER
COLLABORATIVE TOOLS
CLIENT SIDE ONLINE ROBOTS CONTROLLER
VISUALLY GUIDED GRASPING
PDA CONTROL
TCP/IP (SOCKETS)
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SERVER SIDE SERVERS MANAGER CORBA
EXPERIMENTS (ALGORITMS) Public class Experiment1 main(){ for (i=0;!(end); i++){ ... } }
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MENTOR II SERVER
CORBA MENTOR II SERVER
HTTP CÁMARAS
JDBC DATABASE SERVER
DATABASE
TELE-LABORATORY
Figure 2: Remote Programming Software Architecture
3. System Architecture In figures 3 and 4 we can appreciate how the PDA and mobile phone user interface enables access to the 3D virtual and augmented reality predictive display, the robot commands as well as the camera inputs.
Figure 3: Personal Java User Interface for PDA’s
Figure 4: MIDP user interface for mobile phones
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4. System Performance The experiments proposed in this section are related to using TCP or UDP as communication media between the PDA or Mobile Phone and the Tele-Laboratory. The kinds of commands sent from the mobile phone to the robot are in a high level manner (i.e. “Grasp object 2”), so it means we just need IP datagrams that have just a few bytes to carry. In a first glance, we sent 400 commands to the robot from the mobile phone, studying the time invested in communications, robot movement and user Interface itself. As seen in Figure 5, controlling the robots on the same city through ADSL, the results are very similar between UDP and TCP. We must notice that in situations like network overload, UDP would not assure us the packet would reach the server properly.
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Figure 5 - Timing UDP vs TCP (1): Same City ADSL In Figure 6 we can appreciate the results on campus.
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Figure 61 - Timing UDP vs TCP (2): On campus using Fast Ethernet This time we can better apréciate the highest velocity of UDP. TCP delay is around 50 msec and UDP around 5ms. However, as TCP takes care of the network reliability, we assume the TCP delay is good enough for our application. Client/Server connectivity through TCP/IP & UDP/IP on cam pus using Java client and Java server
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5. Conclusions In this paper we have introduced the control of several robots by using a single PDA or mobile phone as input. The user interface enables the operator to have a 3D prediction of the remote robot scenario, which is very convenient in situations of high latency.
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Results show that using a low level bandwith channel (modem connection) is still possible, due to the fact that messages from the mobile phone to the remote robot are sent in a very high level language (e.g. “Grasp the object 1”). Acknowledgements This work has partially been funded by the Spanish CICYT (Ministry of Science and Technology) under Grants TIC2003-08496, DPI2001-3801, DPI2004-01920, TSI2004-05165-C02-01, by the Fundació Caixa Castelló under Grants P1-1B2002-07, P1-1B2003-15, and P1-1A2003-10, and by the Generalitat Valenciana under grant GV04A-698. References [1] [Terrence Fong a, François Conti b, Sébastien Grange b, Charles Baur b, Charles Torpe a, Betty Glass c] a The Robotics Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 USA b L’Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne EPFL, Switzerland c CIS-SAIC, 8100 Shafer Parkway, Littleton, CO 80127 (Advanced Teleoperation Interfaces http://vrai-group.epfl.ch/projects/ati/)
[2] H. Kaymaz-Keskinpala, J. A. Adams, and Kazuhiko Kawamura, "PDA–Based Human–Robotic Interface," 2003 IEEE International Conference on Systems, Man, and Cybernetics. Washington, DC., October, 2003.
[3] J. A. Adams and H. Kaymaz-Keskinpala, "Analysis of Perceived Workload when using a PDA for Mobile Robot Teleoperation," 2004 IEEE International Conference on Robotics and Automation, (submitted to). April, 2004.
[4] H. Kaymaz-Keskinpala, PDA-Based Teleoperation Interface for A Mobile Robot. Master's Thesis, Department of Electrical Engineering and Computer Science, Vanderbilt University. May 2004.
[5] A. Joshi. A PDA Enabled Wireless Interface for a Mobile Robot. M.S. Thesis, 2003. (http://vorlon.cwru.edu/~vxl11/NetBots/AmishiJoshi.pdf)
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