This paper is concerned with multi-user haptic simulation environments in which users can interact across an Ethernet-based Local Area Network (LAN) or a Metropolitan Area Network (MAN). Using network protocols such as the UDP and TCP/IP under normal network traffic conditions, the achievable real-time packet communication rate can be well below the 1 kHz update rate suggested in the literature for high fidelity haptic rendering. However by adopting a multi-rate control strategy, the local control loops can be executed at a much higher rate than that of the data packet transmission between the user workstations. Within such a framework, two control architectures, namely centralized and distributed are presented. Mathematical models of the controllers are developed and used in a comparative analysis of their stability and performance. The results of such analysis demonstrate that the distributed control architecture has greater stability margins and outperforms the centralized controller. It is also shown that the limited network packet transmission rate can degrade the haptic fidelity by introducing a viscous damping into the perceived impedance of the virtual object. Using the proposed models, this damping value is calculated and compensated by active control. Experiments conducted with a dual-user/dual-finger haptic platform confirm the analytical results.
Araki, M. and Yamamoto, K. (1986). Multivariable multirate sampled-data systems: state-space description, transfer characteristics, and Nyquist criterion. IEEE Transactions on Automatic Control31(2): 145—154.
2.
Arioui, H., Kheddar, A., and Mammar, S. (2002). A predictive wave-based approach for time delayed virtual environments haptics systems. IEEE International Workshop on Robot and Human Interactive Communication, pp. 134—139.
3.
Astley, O. and Hayward, V. (1998). Multirate haptic simulation achieved by coupling finite element meshes through Norton equivalents. In Proceedings of the IEEE International Conference on Robotics and Automation , pp. 989—994.
4.
Astrom, K. and Wittenmark, B. (1997). Computer-Controlled Systems: Theory and Design , 3rd Edition, Englewood Cliffs, NJ, Prentice-Hall.
5.
d'Aulignac, D., Balaniuk, R. and Laugier, C. (2000). A haptic interface for a virtual exam of the human thigh. Proceedings of the IEEE International Conference on Robotics and Automation, pp. 2452—2457.
6.
Barbagli, F., Prattichizzo, D. and Salisbury, K. (2005). A multirate approach to haptic interaction with deformable objects single and multipoint contacts. The International Journal of Robotics Research24(9): 703—715.
7.
Basdogan, C., Ho, C.-H., Srinivasan, M. and Slater, M. (2000). An experimental study on the role of touch in shared virtual environments. ACM Transactions on Computer—Human Interaction7(4): 443—460.
8.
Buttolo, P., Oboe, R. and Hannaford, B. (1997). Architectures for shared haptic virtual environments . Computers and Graphics21: 421—429.
9.
Carignan, C. and Olsson, P. (2004). Cooperative control of virtual objects over the Internet using force-reflecting master arms. Proceedings of the IEEE International Conference on Robotics and Automation, pp. 1221—1226.
10.
Cavusoglu, M. and Tendick, F. (2000). Multirate simulation for high fidelity haptic interaction with deformable objects in virtual environments. In Proceedings of the IEEE International Conference on Robotics and Automation, pp. 2458— 2464.
11.
Cho, C., Kim, M., Hwang, C.-S., Lee, J. and Song, J.-B. (2005). Stable haptic display of slowly updated virtual environment with multirate wave transform. Proceedings of the IEEE International Conference on Robotics and Automation, pp. 2465—2470.
12.
Colgate, J. and Schenkel, G. (1997). Passivity of a class of sampled-data systems: Application to haptic interfaces. Journal of RoboticSystems14(1): 37—47.
13.
Constantinescu, D., Salcudean, S. and Croft, E. (2005). Haptic rendering of rigid contacts using impulsive and penalty forces. IEEE Transactions on Robotics21(3): 309—323.
14.
Hannaford, B. and Ryu, J. (2002). Time-domain passivity control of haptic interfaces . IEEE Transactions on Robotics and Automation18(1): 1—10.
15.
Hayward, V., Astley, O., Cruz-Hernandez, M., Grant, D., and Robles-De-La-Torre, G. (2004). Haptic devices and interfaces . Sensor Review24(1): 16—29.
16.
Hikichi, K., Morino, H., Sezaki, I.A.K., and Yasuda, Y. (2002). The evaluation of delay jitter for haptics collaboration over the Internet. IEEE Global Telecommunications Conference, pp. 17—21.
17.
Jeffay, K., Hudson, T. and Parris, M. (2001). Beyond audio and video: multimedia networking support for distributed, immersive virtual environments. Euromicro Conference, pp. 300—307.
18.
Mahvash, M. and Hayward, V. (2003). Passivity-based high-fidelity haptic rendering of contact. Proceedings of the IEEE International Conference on Robotics and Automation, pp. 3722—3728.
19.
Melder, N. and Harwin, W. (2003). Improved rendering for multi-finger manipulation using friction cone based god-objects. In Proceedings of Eurohaptics Conference, pp. 82— 85.
20.
Park, K.S. and Kenyon, R. (1999). Effects of network characteristics on human performance in a collaborative virtual environment. In Proceedings of Virtual Real Annual International Symposium, pp. 104—111.
21.
Ryu, J.-H., Kim, Y., and Hannaford, B. (2004). Sampled- and continuous-time passivity and stability of virtual environments. IEEE Transactions on Robotics20(4): 772—776.
22.
Salcudean, S.E. and Vlaar, T.D. (1997). On the emulation of stiff walls and static friction with a magnetically levitated input/output device. Transactions of the ASME Journal of DynamicalSystems119(1): 127—132.
23.
Shen, X., Zhou, J., Saddik, E. and Georganas, A. (2004). Architecture and evaluation of tele-haptic environments . In IEEE International Symposium on Distributed Simulation and Real-Time Applications, pp. 53—60.
24.
Sirouspour, M., Dimaio, S., Salcudean, S., Abolmaesumi, P., and Jones, C. (2000). Haptic interface control-design issues and experiments with a planar device. Proceedings of the IEEE International Conference on Robotics and Automation, pp. 789—794.
25.
Traylor, R., Wilhelm, D., Adelstein, B. and Tan, H.Z. (2005). Design considerations for stand-alone haptic interfaces communicating via UDP protocol. In Proceedings of World Haptics Conference, pp. 563—564.
26.
Wang, D., Tuer, K., Rossi, M., Ni, L., and Shu, J. (2003). The effect of time delays on tele haptics. Proceedings of Haptic, Audio and Visual Environments and Their Applications , pp. 7—12.
27.
Wang, D., Wang, Y., Lee, Y.-S., Peijun, L. and Wang, Y. (2005). Cutting on triangle mesh: local model-based haptic display for dental preparation surgery simulation. IEEE Transactions on Visualization and Computer Graphics, 11(6): 671—683.
28.
Waters, R. and Barrus, J.W. (1997). The rise of shared virtual environments. International Symposium on Hapanic Interfaces for Virtual Environment and Teleoperator Systems, pp. 20—25.
29.
Yoshikawa, T. and Ueda, H.1996. Construction of virtual world using dynamics modules and interaction modules. Proceedings of the IEEE International Conference on Robotics and Automation, pp. 2358—2364.
