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This paper focuses on the scenario where rotary-wing UAVs complete information collection mission cooperatively. For the first time, we study the problem of minimizing the mission completion time for a multi-UAV system in a monitoring scenario when considering the information collection quality. The mission completion time includes flying time and hovering time. By optimizing the trajectories of all UAVs, we minimize the mission completion time while ensuring that the information of each sensor is collected. This problem can be formulated as a mixed-integer non-convex one which has been proved to be NP-hard. To solve the formulated problem, we first propose a hovering point selection algorithm to select appropriate hovering points where the UAVs can sequentially collect the information from multiple sensors. We model this problem as a BS coverage problem with the information collection quality in consideration. Then, we use a min-max cycle cover algorithm to assign these hovering points and get the trajectory of each UAV. Finally, with the obtained UAVs trajectories, we further consider the UAVs can also collect information when flying and optimize the time allocations. The performance of our algorithm is verified by simulations, which show that the mission completion time is minimum compared with state-of-the-art algorithms.<\/jats:p>","DOI":"10.3390\/s19184032","type":"journal-article","created":{"date-parts":[[2019,9,19]],"date-time":"2019-09-19T03:40:06Z","timestamp":1568864406000},"page":"4032","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":32,"title":["Completion Time Minimization for Multi-UAV Information Collection via Trajectory Planning"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5363-6107","authenticated-orcid":false,"given":"Zhen","family":"Qin","sequence":"first","affiliation":[{"name":"College of Communications Engineering, Army Engineering University of PLA, Nanjing 210042, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Aijing","family":"Li","sequence":"additional","affiliation":[{"name":"College of Communications Engineering, Army Engineering University of PLA, Nanjing 210042, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0183-0087","authenticated-orcid":false,"given":"Chao","family":"Dong","sequence":"additional","affiliation":[{"name":"College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haipeng","family":"Dai","sequence":"additional","affiliation":[{"name":"Department of Computer Science and Technology, Nanjing University, Nanjing 210023, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhengqin","family":"Xu","sequence":"additional","affiliation":[{"name":"College of Communications Engineering, Army Engineering University of PLA, Nanjing 210042, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,9,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"515","DOI":"10.1109\/JSEN.2015.2456931","article-title":"A connectivity-aware approximation algorithm for relay node placement in Wireless Sensor Networks","volume":"16","author":"Ma","year":"2015","journal-title":"IEEE Sens. 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