Mission-level Path Planning And Smoothing Of Lunar Rover Based On Grid Map

The environment of lunar surface is complicated. It cannot be described just bydual-value model–obstacle and non-obstacle, but by extracting the various terraintraits to integrate analysis. Besides, the condition of solar illumination andcommunication with earth changes as system of solar-earth-lunar runs. It isnecessary to model the lunar surface environment with ephemeris. Within theprocess of running, lunar rover needs to accomplish series of missions like moving,sensing, detecting, communicating, charging etc. These missions are limited oraffected by terrain, time and energy, tightly related to path. So, in order to get a pathwhich meets these missions’ requirements, adding all these factors into pathplanning is extremely needful. The initial path will have excessive turns whichmake the path unsmooth. That hardens path-following control for lunar rover. Sosubsequent smoothness handling is also required. This article researches on themission-level path planning and handling the initial path for smoothness.Firstly, combined with the statistical distribution of stones and craters, simulatethe digital elevation model of lunar surface terrain. After dividing the whole terraininto grids, extract terrain characters like pitch, roughness within each grid. Userolling window to analyse the whole terrain feature. Then get the comprehensivesmoothness function and specify the distribution.Secondly, analyse the mutual effect of terrain, solar illumination,communication to earth and list the essential actions to describe the total missionprocess. Given the basic missions are affected by illumination and communicationto earth, use STK to get the ephemeris of solar-earth-lunar. With this dynamicmodel, simulate the distribution of illumination and communication on relatedsurface. Set the cost function of time and energy according to backward A*algorithm. Simulate the appropriate path under these two cost function as well asthe actions’ sequence.Finally, in order to deal with the direction limitation of grid map, calculate thepath cost with interpolation idea which is well used in Field D*algorithm, get amuch smoother path. However, the new path still has some abnormal turns andsome section is slightly shaking. So, make a further smoothing with lunar rover’smotion constraint and draw the key points on the path.