In the future lunar exploration programs of China, soft landing, sampling and returning will be realized. For lunar explorers such as Rovers, Landers and Ascenders, the inertial navigation system （INS） will be used ...In the future lunar exploration programs of China, soft landing, sampling and returning will be realized. For lunar explorers such as Rovers, Landers and Ascenders, the inertial navigation system （INS） will be used to obtain high-precision navigation information. INS propagates position, velocity and attitude by integration of sensed accelerations, so initial alignment is needed before INS can work properly. However, traditional ground-based initial alignment methods cannot work well on the lunar surface because of its low rotation rate （0.55°/h）. For solving this problem, a new autonomous INS initial alignment method assisted by celestial observations is proposed, which uses star observations to help INS estimate its attitude, gyroscopes drifts and accelerometer biases. Simulations show that this new method can not only speed up alignment, but also improve the alignment accuracy. Furthermore, the impact factors such as initial conditions, accuracy of INS sensors, and accuracy of star sensor on alignment accuracy are analyzed in details, which provide guidance for the engineering applications of this method. This method could be a promising and attractive solution for lunar explorer＇s initial alignment.展开更多
Agricultural economic development of Tibet Autonomous Region mainly concentrates in the "One River and Two Streams" agricultural production basin. The basin is main concentrated place for agricultural resour...Agricultural economic development of Tibet Autonomous Region mainly concentrates in the "One River and Two Streams" agricultural production basin. The basin is main concentrated place for agricultural resources development,economic construction and population aggregation,and the region playing the advantages of Tibetan agriculture,corresponding with the practice,and enhancing self development and innovation. In the multi-year development and construction,it develops regional large agriculture,builds irrigation and water conservancy facilities,vigorously changes medium and low-yield land,actively develops animal husbandry and agriculture,and gradually promotes the effective combination of traffic industry and transportation industry,which has made considerable achievements. But in the face of today's increasingly advocated theme of "building beautiful Tibet and constructing ecological home",the construction of environmental problems lacking the systemic research is the prominent and fundamental problem in the "One River and Two Streams" agricultural production basin. Meanwhile,environment construction is an important part of economic development planning,and the solving of environmental protection problem is the historical mission in the contemporary and future generations. Therefore,it is very necessary to study the environment problems in Tibet "One River and Two Streams" agricultural production basin. The "One River and Two Streams" agricultural production basin is preliminarily explored for providing reference for the relevant environmental departments.展开更多
基金supported by the National Natural Science Foundation of China(61233005)the Program for New Century Excellent Talents in University(NCET-11-0771)the Aerospace Science and Technology Innovation Fund(10300002012117003)
文摘In the future lunar exploration programs of China, soft landing, sampling and returning will be realized. For lunar explorers such as Rovers, Landers and Ascenders, the inertial navigation system （INS） will be used to obtain high-precision navigation information. INS propagates position, velocity and attitude by integration of sensed accelerations, so initial alignment is needed before INS can work properly. However, traditional ground-based initial alignment methods cannot work well on the lunar surface because of its low rotation rate （0.55°/h）. For solving this problem, a new autonomous INS initial alignment method assisted by celestial observations is proposed, which uses star observations to help INS estimate its attitude, gyroscopes drifts and accelerometer biases. Simulations show that this new method can not only speed up alignment, but also improve the alignment accuracy. Furthermore, the impact factors such as initial conditions, accuracy of INS sensors, and accuracy of star sensor on alignment accuracy are analyzed in details, which provide guidance for the engineering applications of this method. This method could be a promising and attractive solution for lunar explorer＇s initial alignment.
基金Sponsored by Finance Item of Tibet Autonomous Region
文摘Agricultural economic development of Tibet Autonomous Region mainly concentrates in the "One River and Two Streams" agricultural production basin. The basin is main concentrated place for agricultural resources development,economic construction and population aggregation,and the region playing the advantages of Tibetan agriculture,corresponding with the practice,and enhancing self development and innovation. In the multi-year development and construction,it develops regional large agriculture,builds irrigation and water conservancy facilities,vigorously changes medium and low-yield land,actively develops animal husbandry and agriculture,and gradually promotes the effective combination of traffic industry and transportation industry,which has made considerable achievements. But in the face of today's increasingly advocated theme of "building beautiful Tibet and constructing ecological home",the construction of environmental problems lacking the systemic research is the prominent and fundamental problem in the "One River and Two Streams" agricultural production basin. Meanwhile,environment construction is an important part of economic development planning,and the solving of environmental protection problem is the historical mission in the contemporary and future generations. Therefore,it is very necessary to study the environment problems in Tibet "One River and Two Streams" agricultural production basin. The "One River and Two Streams" agricultural production basin is preliminarily explored for providing reference for the relevant environmental departments.
