Research On Technology Of A New Kind Of Lunar Rover Mobile System And Its Experimental Program

The success of the first stage of Chang'e Project indicates that the Chinese as-tronautics has entered a new era of deep space exploration. In the second stage ofunmanned lunar exploration, lunar rover will play a very important role. The re-search areas of lunar rover are very extensive, however only a few aspects of newkine of lunar rover are illustrated in this dissertation.The mobile system is the key part of lunar rover,which determines the efficacyof lunar exploration. The surface of the moon is such complicated that the wholeterrain is covered by loose soil, different sizes of rocks and sands, and obstacleslike gullies. Therefore, it is necessary for the lunar rover to be capable of crossingover obstacles and the gullies. Especially when the slipping of one or more wheelsoccurs, the lunar rover could still move with enough traction. In view of the aboverequirements, a new kind of mobile system of a six-wheeled lunar rover is designed.The Six wheels, set asymmetrically at both sides of rover body, could be driven in-dependently. They are equivalent to six wheel axles, increasing the ability of cross-ing over obstacles. And there are also motors in the joints of rocker arms, which canassist in crossing by raising wheels and redistribute the loading weight. Moreover,when one or more wheels slip, the rover can still get proper traction from thesemotors and also the wheels are easily folded up to be fixed in cowling.Considering the new kine of lunar rover, Newton-Euler method is adopted todeduce the equations of centroid movement of overall rover, rotary movementaround mass center, rotary motion of suspension levers for suspension points anddrive equations for wheels. Meanwhile, the geometry and velocity constraints aregiven. As the layout of wheel arrangement are asymmetric and the the dynamicequations are differential-algebraic equations, the difficulty of solving equations isincreased. So the finite difference method is employed to solve equations in thisdissertation. The parameters of soil for experiment are measured using the terra-mechanics principle. The performances of rover motions on flat and slope terrain,climbing obstacle and passing ditch are analyzed by simulation, and through simu-lation, certain useful results are acquired for drive. According to the dynamicsimulation results, several verifying experiments of lunar rover movements are car- ried out in 7×9 m2 test bed. The lunar rover has the ability to climb obstacle of 0.2m which is higher than wheel radius and pass ditch of 0.3m which is wider than wheel diameter. The experimental results verify dynamic model and the simulation results.The monocycle air-float experimental equipment for lunar rover is designed, which could be used to research the working condition of lunar rover in six to one gravity on earth and study wheel-soil interaction terramechanics and the wheel working features. The equipment employs gas lubrication technique in horizon and vertical and the gas bearing has the advantages of less friction and smooth move-ment. Due to these advantages, the immeasurable friction of sliding track can be bucked and get accurate experiment results. The servo system for level tracking system is designed to isolate the variable, irregularity disturbance of electric cables and air pipes caused by pallet moving and guarantee the precision of system. By using the experimental equipment, the following researches can be carried out: sin-gle wheel drive dynamics and control performance, each wheel brake and promote mutually, wheel-soil interaction terramechanics experiments and changing tractive ability of motion system for the new kind of lunar rover.An attitude and position estimation system for lunar rover based on colored dot targets is proposed. This system consists of two cameras assembled at the descend stage of lunar vehicle and a laser ranger finder. Utilizing the dot targets on lunar rover, the attitude and position of the rover can be determined. Considering the connection region analysing method porposed by James Bruce, an attitude and po-sition estimation algorithm is proposed.The computer simulation indicates the cal-culation speed and presision of the algorithm can meet the requirements, also the altorichm has certain robustness for noise. The experiment in 7×9 m2 test bed shows the efficiency of this attitude and position estimation method. The precision of this method is enough for most applications.