Research On Precision Of Soil Bin Test System Of Interaction Between Lunar Soil And Wheel

The detailed understanding of lunar soil physical and mechanical properties can help avoid unnecessary risks especially when the lunar rover and robots inspect the menology , manned rover lands on the moon and when the astronauts walk on the lunar surface. The importance of safety of space missions can not be overemphasized.And it's also very important to protect the safety of space missions. To implement the Moon Exploration Project ,an advance lunar rover technology is indispensable. In the future exploration of the moon,the lunar rover with all kinds of scientific instruments is needed to complete various scientific experiments. It is necessary for the moon to have high-performance such as adapting to the surface of the moon's complex environment,passing the soft soil smoothly and crossing through certain barriers,in order to fulfill these scientific experiments.The characteristics of lunar soil has greater impact on the design of the lunar rover. At the same time,a kind of simulative soil is developed based on analyzing the physical and mechanical properties of the lunar soil for the test of this thesis research. In order to analyze the mechanical properties of the wheel,optimization of the design of wheel and comparison of properties of different wheels were carried out in this study.The deep space exploration vehicles are similar to the study objects of the vehicles on the ground .But because of the peculiarity of the deep space exploration vehicles,it is very difficult to carry out the actual field test,therefore the research means and methods should mainly refer to the ground vehicles'research methods. This paper examined a large amount of information on the study of wheel mechanics and soil bin at home and overseas from the early 1990s to current,to offer reference to the design of the soil bin test system..On this basis,a soil bin test system with simulative lunar soil is designed according to the functional needs of the system. The paper then introduced in detail the design process of soil bin test system,and respectively describes design concepts and design principles of the bench structure,drive system,the survey and control systems and software system,then introduced the operating process of the test system. The characteristics of lunar soil have great impact on the design of the lunar rover. In addition, the bearing strength and the friction coefficient between the particles and the cohesion all affect the walking and climbing performance of the lunar rover. The lunar rover should be able to be maneuvered as follows: forward and backward steering and other motor function on the loose soil , adapt to the environment of lunar surface morphology. The simulative soil is developed to complete the relevant tests because the lunar soil is extremely valuable and not readily available. Material obtained from volcanic eruption in Jilin Huinan is used as primary material and the hematite is used as auxiliary material,and through proportion,direct shear,bearing weight and so on ,physical and mechanical parameters of the Simulative lunar soil is determined. The test proves that the parameters are all within the scope of the lunar soil samples.Through a series of debugging tests and pre-commissioning tests , some problems are resolved and the performance of the testing system is found out: wheel diameter≤400 mm;rotational speed≤20 rpm;traction resistance≤5000N; sinkage≤600 mm; but the control accuracy especially the speed and the force control still needs to improve.Then ADAMS simulation software is used to build a model of the test system in order to save cost and time. The result of the simulation indicates that the former soil bin certainly has some problem and also ,show that if these problems were solved,then the system will run smoothly. Next,the test is used to verify whether the improved system can attain the required accuracy and precision of the test system.The PLC is the core of the whole soil bin testing system,which through reversible DC motor control system complete the feedback control,after collecting motor speed,the data will be transmitted to IPC for further analysis,processing and display. At the same time IPC can select the rotational speed of the reversible motor and implement orders such as start,stop and so on to realize the debugging and control of the traction system. After using EDC controller in soil bin testing system,a great deal of improving the comparative test,including changes in elastic rope test,and air trip test,different speeds,load,material,the wheels of the pilot and control experiment,the results show that after using the EDC controller the speed and the force control of soil testing system is under basic stability. However,the experiment shows that the force control remains vertiginous all the same. Therefore,for the original testing of the control system a kind of hanging poise at the wire rope of the traction control is used to improve the testing system. A series of tests verified that this way can solve the issue of force control instability.The result of the study indicate that the test system can provide drive force and load that we need,and can implement test of the vertical displacement,a clinical displacement,torque,resistance,rotate speed,the slip of the driving wheel and so on. At the course of the system debugging,we resolve the problem of the leap of the date and we actualize two kinds of amelioration against the problem of the unstable control of the tractive resistance and the forward speed. At last, the improved system can allow the implementation of the test of the tractive capability of the lunar rover.