無線感應器網路(Wireless Sensor Network)是由許多感應器(Sensor node)所組成，感應器主要是在特定的感應範圍內監控某物體或環境的變化，感應器經由無線感應器網路傳回感應結果給使用者，在民生、軍事、航太或是醫學都有廣泛的應用。在無線感應器網路中感應器大部份都是以電池來當作主要電力來源，常常有一些感應器因為工作量較大而容易沒電，這樣會這成整個網路不連通且失去重要的感測資訊。因此在本篇論文中，我們設計與實作出一個可移動式感應器，利用此可移動式感應器來尋找出網路中快沒電的感應器並放置一個新的感應器來取代沒電的感應器。我們提出一個引導可移動式感應器的演算法，此演算法不需要任何的感應器位置資訊，只需要利用收到的訊號強度來引導可移動式感應器。由實驗結果證明，可移動式感應器能利用我們所提出來的演算法成功的到達目的地。

Most wireless sensor networks consist of a large number of static, low-power, short-lived, and unreliable sensors. We consider sensor networks that consist of static and mobile nodes. Integrating both types of devices enables new applications such as node replacement, location assignment, hole and partition recovery, autonomous deployment and redeployment, and dynamic sensing. In this thesis, we design a smart mobile sensor node to implement an application of replacement. There are some sensor nodes easy to exhaust their energy because of heavy workload. It will cause the wireless sensor network be partitioned into subgroups. We present a node replacement algorithm by using our implemented mobile sensor nodes. In our algorithm, the mobile sensor nodes can navigate to the low-energy sensor nodes and replace them by disposing new sensor nodes automatically without any location information. The navigation algorithm is based on signal strength received between the communication nodes. Finally, we experiment results show that the mobile sensor nodes could achieve their tasks successfully.

[1] A. Galstyan, B. Krishnamachari, K. Lerman, and S. Pattem, “Distributed Online Localization in Sensor Networks Using a Moving Target,” in Proceedings of the Third International Symposium on Information Processing in Sensor Networks (IPSN 2004), pp. 61-70, California, USA, April, 2004.
[2] A. Mainwaring, J. Polastre, R. Szewczyk, D. Culler, and J. Anderson, “Wireless Sensor Networks for Habitat Monitoring,” in Proceedings of the First ACM International Workshop on Wireless Sensor Networks and Applications (WSNA 2002), pp. 88-97, Georgia, USA, September 2002.
[3] C.-Y. Chong and S.P. Kumar, “Sensor Networks: Evolution, Opportunities, and Challenges,” in Proceedings of the IEEE, Vol. 91, No. 8, pp. 1247-1256, August 2003.
[4] D. Estrin, R. Govindan, J. Heidemann, and S. Kumar, “Next Century Challenges: Scalable Coordination in Sensor Networks,” in Proceedings of the 5th Annual ACM/IEEE International Conference on Mobile Computing and Networking (MOBICOM), pp. 263-270, Washington, USA, August, 1999.
[5] F. Dellaert, D. Fox, W. Burgard, and S. Thrun, “Monte Carlo Localization for Mobile Robots,” in Proceeding of the 1999 IEEE International Conference on Robotics and Automation (ICRA 1999), pp. 1322-1328, Detroit, Michigan, USA, May, 1999.
[6] G. T. Sibley, M. H. Rahimi, and G. S. Sukhatme, “Robomote: A Tiny Mobile Robot Platform for Large-Scale Ad-hoc Sensor Networks,” in Proceedings of the 2002 IEEE International Conference on Robotics and Automation (ICRA 2002), pp. 1143-1148, Washington, DC, USA, May 2002.
[7] G. Wang, G. Cao, and T. LaPorta, “A Bidding Protocol for Deploying Mobile Sensors,” in Proceedings of the 11th IEEE International Conference on Network Protocols (ICNP 2003), pp. 315-324 , Atlanta, Georgia, USA, November, 2003.
[8] H. Yang and B. Sikdar, “A Protocol for Tracking Mobile Targets using Sensor Networks,” in Proceedings of the First IEEE International Workshop on Sensor Network Protocols and Applications (SNPA 2003), pp. 71-81, Alaska, USA, May 2003.
[9] I.F. Akyildiz, W. Su, Y. Sankarasubramaniam, and E. Cayirci, “A Survey on Sensor Networks,” in IEEE Communication Magazine, Vol. 40, No. 8, pp. 102-114, August 2002.
[10] J. Culpepper, L. Dung, and M. Moh, “Hybrid indirect transmissions (HIT) for data gathering in wireless micro sensor networks with biomedical applications,” in Proceedings of 2003 IEEE 18th Annual Workshop on Computer Communications, pp. 124-133, California, USA, October 2003.
[11] J. Hill, R. Szewczyk, A. Woo, S. Hollar, D. E. Culler, and K. S. J. Pister, “System Architecture Directions for Networked Sensors,” in Architectural Support for Programming Languages and Operating Systems, pp. 93-104, Boston, MA, USA, November 2000.
[12] K. O. Arras, N. Tomatis, B. T. Jensen, and R. Siegwart, “Multisensor on-the-fly Localization: Precision and Reliability for Applications,” in Robotics and Autonomous Systems, Vol. 34, No. 2-3, pp. 131-143, February, 2001.
[13] L. Schwiebert, S. K. S. Gupta, and J. Weinmann, “Research Challenges in Wireless Networks of Biomedical Sensors,” in The Seventh Annual International Conference on Mobile Computing and Networking, pp. 151-165, Rome, Italy, July, 2001.
[14] M. A. Batalin and G. S. Sukhatme, “Efficient Exploration Without Localization,” in Proceedings of the 2003 IEEE International Conference on Robotics and Automation (ICRA 2003), pp. 2714-2719, Taipei, Taiwan, September 2003.
[15] M. B. McMickell, B. Goodwine, and L. A. Montestruque, “MICAbot: A Robotic Platform for Large-Scale Distributed Robotics,” in Proceedings of the 2003 IEEE International Conference on Robotics and Automation (ICRA 2003), pp. 1600-1605, Taipei, Taiwan, September 2003.
[16] P. Corke, S. Hrabar, R. Peterson, D. Rus, S. Saripalli, and G. Sukhatme, “Autonomous Deployment and Repair of a Sensor Network using an Unmanned Aerial Vehicle,” in Proceedings of the 2004 IEEE International Conference on Robotics and Automation (ICRA 2004), pp. 3602-3609, New Orleans, LA, USA, April, 2004.
[17] S. Bergbreiter and K. S. J. Pister, “CotsBots: An Off-the-Shelf Platform for Distributed Robotics,” in Proceedings of the 2003 IEEE/RSJ International Conference on Intelligent Robots and Systems (IRSO 2003), pp. 1632-1637, Las Vegas, Nevada, October 2003.
[18] D. J. Goodman, “Wireless Personal Communications Systems,” Addison Wesley, USA, 1998.
[19] R. Neapolitan and K. Naimipour, “Foundations of Algorithms,” Jones and Bartlett, London, UK, 2003.
[20] Atmel Corporation: Online available at: http://www.atmel.com
[21] Chipcon Inc.: Online available at: http://www.chipcon.com
[22] Crossbow Technology Inc.: Online available at: http://www.xbow.com
[23] NesC: Online available at: http://nescc.sourceforge.net
[24] TAMIYA Inc.: Online available at: http://www.tamiya.com
[25] TinyOS: Online available at: http://webs.cs.berkeley.edu/tos
[26] TOSHIBA Corporation: Online available at: http://www.semicon.toshiba.co.jp