Configuration Design And Parameter Optimization For Lunar Surface Grab Sampling End-effector

The main target of the third stage of China lunar exploration project is sampling onthe moon automatically and returning the samples for research on the earth. The surfacesampling of lunar regolith, which can be conducted several times on different places, is akey component of the automatically sampling mission. The samples collected can beused to study the geological information of lunar soil and the environment effects.Furthermore, the surface sampling, with the characteristics of large sampling volume andhigh adaptability, can enhance the reliability of the entire mission. The application ofsurface sampling manipulator has been proved successfully in planetary explorationsampling tasks. As the functional component of the surface sampling manipulator, theend-effector determines the way of sampling and the result of the mission. So it is ofgreat importance to study the end-effector of surface sampling manipulator.Aimed at lunar regolith sampling and packaging mission, a scheme of single-drivegrab sampling with primary packaging device integrated is proposed, which solves thecontradiction between function integration and structure complexity. A variety offeasible sampling mechanism symbolic schemes are generated by symbolic innovationdesign based on the design model built under the theory of mechanism. The optimalscheme of sampling mechanism is determined by fuzzy evaluation and the correspondingintegrated packaging device is designed.To understand the mechanical properties of grab sampling, a parametric grabsampling model is established. Analysis of sampling resistance is carried out under soilmechanics theory considering the lunar physical and mechanical properties. The formand characteristic of load of end-effector is realized and the difficult point of grabsampling is confirmed. The influence of lunar mechanics parameter is studied, and theresistance response to structure parameter is obtained in order to lay the foundation forfurther parameter optimization.The optimal sampling process is investigated. With the goal of maximum ofcollected samples, the sampling parameters and structure parameters is optimized. Tofurther study the optimal sampling process, the multiobjective optimization of samplingvolume and resistance torque is implemented based on genetic algorithm. The Pareto setis got and the optimal sampling process is determined. According to the optimization result, simulation model of sampling mechanism is created in Adams/View and theoptimization of the rest structure parameters is conducted under the correspondingresistance torque. The kinematics and mechanics characteristic is validated throughsimulation.The attitude deviation of grab sampling process is investigated. The possible typesand causes of sampling attitude deviation are confirmed. The influence of pitch deviationand roll deflection on sampling process is analyzed and the solutions are discussed.