Dynamic Simulation Analysis Of Drill Feeding Mechanism For Lunar Soil Sampling

The core task of the third phase of lunar exploration program of China is to obtain lunar regolith samples in deep layer with original bedding structure.Drilling system of lunar regolith mainly consists of drill feeding mechanism,rotary drive mechanism and percussion mechanism.Drill feeding mechanism works with the transmission of cable-pulley system.It contributes to control the movement of the drilling mechanism precisely,by towing drilling mechanism to feed along the guide rail via wire rope.In order to complete the task of lunar regolith sampling successfully,the cable-pulley system must meet the dynamic performance requirements.Furthermore,in order to work out the parameter optimization scheme,it is necessary to carry on simulation research and performance analysis for the cable-pulley system.It is difficult to build a model for the cable-pulley system.The main study in this paper is how to build dynamic model for the cable-pulley system of drill feeding mechanism.Based on the method of spatial description,it can be proposed to use arc length coordinates to describe the movement of material points on the wire rope.Then it can derive the relationship between material velocity and spatial velocity.The calculation method of the arc length of the wire rope slip on the drum is given.By analyzing the winding method of wire rope on the drive drum,it can calculate the connection of the wire rope on each component based on the geometric structure of drilling mechanism.There are 8 feature points were selected in the mechanism.And based on the condition of compatible displacement and static force equilibrium of the feature points in drilling mechanism,the initial state of drill feeding mechanism can be calculated.According to the analysis of kinematic relationships of feature points,the dynamic model and differential equations of the cable-pulley system are established.By modifying the angular velocity,the intermittent of the angular acceleration was eliminated.Finally,we use Runge-Kutta method to solve the differential equations.Simulation program of drill feeding mechanism is written in MATLAB.Users can enter parameters of the mechanism in GUI.The program will automatically build the dynamic model of mechanism and solve the equations efficiently.The results are showed in the form of animations and curves after handling.The animation of the mechanism is drawn according to the real-time calculation results.It can reflect the working details of each component in the drill feeding mechanism.By analyzing the dynamic responses of the drill feeding mechanism,we can verify the theory and ensure its reliability.It provides a powerful reference for the further design of the mechanism.