Research On Several Key Techniques Of The Mobile System On A Ground Exploration Vehicle

As an important component of a ground exploration vehicle, the riding performance and stability of the moving system will affect the exploration results directly. In order to improve the adaptability on complex ground surface, new moving system of the ground exploration vehicle is studied, and a new wheel-tracked moving system is presented innovatively. Then many relative problems of this new moving system are studied deeply and systematically. The main research contents can be concluded as followings.By analyzing the different moving systems and the design goals, a new wheel-tracked moving system is presented. Many key parts of the moving system are designed and analyzed. A parallelogram mechanism is designed to make first linear average of the hypsography and which can make the exploration vehicle adapt uneven terrain passively. The parallelogram mechanism can also keep the track in the state of tightening. The front track has bigger effective radius, so the new style wheel-tracked mobility system is easy to surmount obstacles because of having a track wheel in its front. The rear wheel and front track are connected to the bodywork by the suspension rocker, this new style connection can average the pressures on the rear wheels and the front tracks, so difficulties in designing the controlling system can be reduced. The left and right suspension rockers are connected with the bodywork by differential balance mechanism, which brings stability and better ability of obstacle surmounting as well as the ability of resisting turnover.Basing on the structure designing, kinematics analysis is made to the wheel tracked exploration vehicle. As the exploration vehicle is always turning by skid steering and should surmount obstacles continually, the new kinematics model of multi-body system fully consideres the above two factors. A new method of Householder transform was presented to solve the exploration vehicle's hyperstatic equations. Comparing to the traditional solving method, new method brings more acute results, short computation time and more stability of numerical values.In order to improve the ride performance and stability of wheel tracked exploration vehicle, a method to establish dynamic model of the moving system is given, which can also be applied to most rocker suspension systems. Then an optimization design model is provided. By using the NSGA-II, main parameters of the suspensions are optimized. The optimization results indicate that the virtual value of bodywork's acceleration namedσ&z2& is reduced by 8.19%, the maximum value of bodywork's acceleration named max (& z&) is reduced by 2.36%, and the maximum value of the dynamic load is reduced by 5.76%. And by optimization, the probability of suspension system's collision is satisfied to the design requirement. Basing on the optimization results, the stiffness coefficient of the torsion spring is selected, that the ride performance is improved further.Whether the wheel tracked exploration vehicle steering on level road or slopes, its mobility and flexibility needs to be improved further. In order to master the kinematics and dynamics laws of the steering state, the steering characteristics are studied. As the exploration vehicle steers by the method of skid steering, the relationship between steering transmission ratio and velocities of two sides'wheels is given. The coefficients of steering resistance ( f w) and steering flexibility (λ) are defined, where f w is regarded as the measurement of whether it can steer smoothly, andλis regarded as the difficulty level of the vehicle's steering. The variation rules of instantaneous centre's longitudinal offset are studied when moving on slopes. The steering resistance moment and traction force are influenced by the azimuth and the gradient of slopes, so the influence rules are analyzed. Basing on the above studies, the distance between the left wheel and the right wheel, the center spacing of front track and rear wheel, and the height of the centroid are determined.The prototype is processed according to the above research results. On basis of the examination conditions, the examinations and tests are made. And it is proved that the maximum gradient that can be climbed over by the vehicle is 42°, the maximum height of the obstacle that can be passed through is 180 mm, and the maximum width of the channel that can be passed through is 150 mm. By testing the pitching angles of the wheel-tracked exploration vehicle, the function of the differential balance mechanism is verified. Then by ride performance testing, the numerical values are contrasted to those coming from theoretical calculations, and the results show that the predigestion method is reasonable and meanwhile the ride performance is verified. At last, tests of the steerings on level road and the slopes are done to verify the theoretical results.In conclusion, by the above design and analysis, the wheel tracked moving system is studies systematically and entirely. Further the new moving system can be better applied to the special tasks.