Mission Planning Technology In Teleoperation Of Lunar Rovers

According to China's lunar exploration program, it is scheduled to land probes on the moon in 2013, carrying out point detection and roving detection on the surface. The lunar rover is the one which will traverse on the moon, and it's also the first Chinese mobile robot working on a celestial body besides earth. As a result of the limited intelligence of lunar rover and abundant communication opportunity to earth, ground-based teleoperation is chosen to be the main approach to control the lunar rover. Planning the activities sequence for a rover, ensuring it to achieve engineering and scientific goals without violating any operation constraints, is the primary mission of ground teleoperation system. Therefore, mission planning technology comes to be a key technology of teleoperation. However, as mission planning is a domain-related technology, neither approaches in other domains nor for other rovers (like mars rovers) can be used for lunar rover. So, developing a mission planning technology for lunar rovers is of great engineering significance and theoretic valuable.This research is directly driven by the practical needs of China's lunar exploration program on planning for the lunar rover. Based on the review of research progress on environment modeling, a synthesized lunar environment model is built for mission planning, in which a mission-level path is proposed and planned. After analyzing the features of activities of lunar rover, a mission planning approach is finally proposed. It considers not only the interaction of mission-level path and path-dependent activity, but also the uncertainty of working on the lunar surface,There are some environmental factors affecting working progress on the moon, including lunar terrain, position of the sun and the moon. Most of the current researches on environment modeling focus on terrain classification and identification. On analyzing the affecting mechanism of environment factors to lunar rover, a synthesized environment modeling approach is proposed to model the lunar environment, which serves as the foundation of mission planning.It usually takes rover a long time to traverse form one goal to another, which is far apart. The environment is continuously varying. Moreover, mission goal is always related to time and energy. Traditional shortest path only avoiding terrain obstacle is not suitable for lunar rover anymore. Traversing on the moon should consider all the global factors. The path is named mission-level path. In chapter 3, mission-level path planning problem is first modeled, followed with a Predictable Dynamic Environment (PDE) path planning method. It turns planning a path on the continuously varying environment to a series of global path searching on static environments.Traverse is one of the activities performing on the moon, but not all. Working progress of lunar rover is directed by a mission plan comprising all kinds of activities. So, activities are descripted and categorized at the beginning of chapter 5. Then, a generalized mission planning method producing activity sequences for lunar rover is finally formulated, based on PDE mission-level path planning approach in chapter 4.Because of the uncertainties of working on the moon, time consumption of every activity during plan execution may not conform to the original plan. Traditional deterministic mission plan will run into difficulties when applying to practical use. To solve this problem, a new flexible plan is proposed, where the beginning time of an activity is of flexibility. It can enhance the practical ability of a mission plan greatly. What's more, a fashion of computing the flexible interval of every activity in a sequence is given out and simulated.