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50 st / July 2014 www.sea-technology.com feasibility and reliability of the rope-throwing device and lifting lock. Seven launch and recovery sea trials were then conduct- ed in the South China Sea from April 20 to May 2, 2013. The sea conditions for most of the tests were generally calm, but the fnal test was conducted in sea state 3. The launch and recovery operations were successfully conducted without small boat assistance, and it took an average of 30 minutes from the recovery rope being thrown to the AUV being back on the Ocean VI deck. The launch and recovery system was further tested dur- ing Qianlong I's ocean deployment in October 2013 in the west Pacifc Ocean, near Hawaii, during which another sev- en launch and recovery sorties were accomplished under sea states up to 4. Conclusion The low-cost launch and recovery system for Qianlong I was developed for use in a variety of readily available ves- sels. A series of trials for launch and recovery operations were done on a lake and at sea during the period of Novem- ber 2012 to October 2013. During sea trials, 14 launch and recovery sorties were conducted, mostly under generally calm sea conditions, but also under sea states 3 and 4. The launch and recovery operations required no small boat as- sistance. The devices used are relatively simple and require no remodeling of the surface vessel. The devices are suitable for most surface vessels with a relatively lower deck and an A-frame on the stern. The key characteristic of the launch and recovery system is its low cost. Acknowledgments Qianlong I is being developed at the Shenyang Insti- tute of Automation (SIA), China, with funding from China's Ocean Mineral Resources Research and Development As- sociation and support from the Natural Science Foundation of China (51109205). We would like to thank Rong Zheng for his help with this article, our colleagues in the Qianlong project, and the master and crew of Ocean VI. n rope onto the vessel's deck, transferring the rope to the stern of the vessel to tow the AUV. As the AUV is towed by the surface vessel, the lifting lock and lever connect the lifting belts to the rings of the AUV. The lever is made of carbon fber and is connected with the lifting lock through ABS plastic, which is a breakable item. The lifting belts and the AUV's rings are connected through the lifting lock with the carbon fber rod as the AUV is be- ing towed. Pulling the carbon fber rod back hard when the lifting rings are locked destroys the breakable item so that the rod separates from the lifting lock. The lifting lock can be separated manually from the lifting rings after the AUV is recovered. The length of the carbon fber lever is nearly 10 meters, and high operational torque was needed at frst. To solve this issue, we loaded a balance weight at the end of the carbon fber rod. Although the overall weight increased after that, the operating torque greatly reduced. To summarize the recovery process, when the AUV com- pletes a detection mission, it foats to the sea surface by throwing away its ballast. Then, the AUV transmits its po- sition to the surface vessel via radio, and the surface ves- sel sails towards the AUV. The projectile head and rope are thrown out of the AUV via remote control when the vessel is about 50 meters away from the AUV. The crew salvages the rope through the rope-capture device, and the rope is pulled in through the A-frame, which is assembled on the stern of the surface vessel. The traction rope is pulled back through the winch on deck, towing the AUV until the AUV is below the A-frame. The lifting dock connects the lifting belts to the rings of the AUV. The AUV is then slung from the water via cable and onto the vessel, then fxed on a special bracket. Launch and Recovery Trials, Results The launch and recovery system was tested in Qiandao Lake in the Zhejiang Province of China from November 2012 to March 2013. We did three simulation experiments for launch and recovery operations at sea, which proved the Jianguo Wu is an associate researcher at Shenyang In- stitute of Automation, Shenyang, China. He received a doctorate in mechanical engineering from Tianjin University in Tianjin, China, in 2010. His research in- terests include general AUV technology, underwater gliders and AUV docking technology. He has been involved in the development and production of vari- ous ocean vehicles since 2006. He is responsible for mechanical systems of the Qianlong I AUV. Huixi Xu received a master's degree in mechani- cal engineering from Northeastern University in Shenyang, China. He is an associate researcher at Shenyang Institute of Automation, Shenyang, China. His research interests include AUV general technol- ogy, deep-sea AUVs and long-endurance AUVs. He has been involved in the development and produc- tion of various ocean vehicles since 2002 and is chief designer of the Qianlong I AUV. Jian Liu was born in 1962 and received a master's degree from Dalian University of Technology in Da- lian, China. He is a researcher of Shenyang Institute of Automation, Shenyang, China. His research interests include AUV general technology and AUV control. He is the chief designer of the Qianlong I AUV and CR02 AUV. He has 13 years of ocean experience with deap-sea AUV research and operations. (Top) Towing the AUV by Ocean VI. (Middle) A lifting belt and the lifting ring. (Bottom) Recovery operation during sea trials.