Kailiang Zhang

Study on the dynamic characteristics of a hammer-driven-type penetrators in the penetration process

Dynamic penetration test by a penetrator is an important detection method for lunar exploration. The analysis of the dynamic penetration properties of the penetrator significantly helps to design the penetrator structure. In this article, the dynamic penetration mechanical model was established according to soil mechanics. Then, the discrete-element simulation model, which was established using the application program interfaces of the EDEM software, was used to simulate the penetration process. The penetration experiment demonstrated the accuracy of the dynamic penetration model and the discrete-element simulation model. This study of dynamic penetration model of a penetrator may provide technical support to the deep space exploration.

Coordinated motion control model of a six-wheeled rocker lunar rover

At present, control methods of the six-wheeled rocker lunar rover primarily consist of setting the same driving parameters for each wheel. This type of control method ignores the multiple active driving characteristics of the lunar rover and causes parasitic power loss. The main cause of the parasitic power loss is the uncoordinated motion of the driving elements. Therefore, in this article, a coordinated motion programming model of the six-wheeled rocker lunar rover based on the velocity projection theorem, the quasi-static mechanical model, and the rated power of the motor is established to eliminate parasitic loss, reduce driving energy, and improve energy efficiency. The analytical solution of the programming model based on the Kuhn–Tucker condition is also calculated. The coordinated motion control model saves energy, and it is suitable for other wheeled-type planet rovers. This model provides technical support for reducing the energy consumption of planet rovers.

The study of the drilling core features of a multi-pipe deep lunar soil sampling driller for manned lunar exploration based on the discrete element technology

Lunar soil sampling is important for human beings to know about the components of lunar soil and the lunar geological structure. By now, lunar soil between the depths 0 and 3 meters is researched, but there are not any drillers which can collect the much deeper lunar soil. In this paper, a multi-pipe driller that can drill 5 meters deep for manned lunar exploration was proposed. In order to verify the reliability of drilling core, the drilling core features of the driller were studied by using the EDEM software. The influences of drill pipes rotation speed and feed rate to the drilling core were studied. The results turned out that the feed rate had a significant influence on the drilling core features and the rotation speed had an important influence on the power and the torque. The simulation results can provide guidance for the optimization of the system structure and the technical supports to Chinas deep lunar soil sampling project.

A simulation study on a digging-typed lunar soil sampling device and its sampling characteristics based on discrete element method

Lunar soil sampling is an important task for lunar probe. It is the premise of the analysis of lunar soil and the study of lunar environment and evolutional history. Lunar soil sampling techniques have different classifications according to different standards. In view of goals of Chinas lunar exploration sampling project, a design of digging-typed lunar soil sampling device based on the mechanical arm is proposed in this paper. Mechanical characteristics of digging sampling process are analyzed in EDEM as well. Analysis results based on discrete element method show the compressive stress distribution of lunar soil particles during the digging process, vertical force and horizontal force of the sampling device during the digging process and the weight of samples in one sampling action. These simulation results prove the feasibility of the sampling device and lay the foundation for Chinas manned lunar exploration in the future.

The research and design of pneumatic multi-pipe deep lunar soil drilling device

This research proposed a pneumatic multi-pipe deep lunar soil drilling device under the background of manned lunar-landing and used coupled simulation by EDEM/Fluent for the drilled process, pneumatic drilling principle has been proved feasible by the simulation result. The drilled device this research proposed can collect lunar soil five meters under the surface, and ensure that the bedding information of the collected lunar soil is complete.

The research on the effects of motion parameter on adhesive ability of a lunar crater exploration rover wheel based on DEM simulation

Lunar soil sampling is the premise of the analysis of lunar soil and the study of lunar environment and evolutional history. Because of the restrictions of the sampling method, the size of drillers, the drilling pressure and the output power of driller, the traditional digging and vertical drilling methods can only acquire the samples from lunar surface to 3 meters deep. In order to acquire deeper samples based on the existing technical methods, a new exploration concept in which a driller fixed on the rover takes a horizontal drilling and sampling at the cross section of a crater after cleaning the surface chaotic soil was proposed in this paper. When drilling horizontally, the maximum drilling pressure is limited by the low adhesive ability between wheels and sandy road. For the purpose of making sure enough drilling pressure, study was carried out in this paper to improve the adhesive ability of wheel by modifying the surface of wheel. A new kind of wheel with micro convex structures was proved to be more adhesive and stable during horizontal drilling by comparing with the existing wheel structures, such as the wheel with thorns or the wheel with discontinuous rims. The motion parameter of wheel has a significant influence on the driving property of wheel. In order to research the effects of motion parameter on adhesive ability of wheel, the process that wheels move on sandy road was simulated using a DEM software EDEM, the simulation results show that though the adhesive ability of wheel with convex structures will decrease with the increase of tangential velocity slightly, its adhesive ability is much higher than the adhesive ability of normal wheel.

Simulation and research on landing impact between lander and lunar regolith based on DEM

Landing-impact between lander and lunar regolith is the decisive factor to soft landing and relates directly to the safety of detection equipment. In this paper, the landing-impact process and the interaction between lander and regolith is researched using the discrete element simulation. Firstly, the landing-impact model is established based on discrete element theory and the mechanical properties of lunar regolith. Many simulations in different working conditions are conducted to study the vertical impact. Secondly, to study the process of landing-impact, dynamic response, stress distribution and motion in a certain condition are studied and the phenomenon of landing impact is explained. Finally, the influence of velocity and mass on the landing-impact is summarized through contrastive analysis. The research in this paper provides reference for the design of lander buffering mechanism and the establishment of the theoretical model.

Study on charging mechanism model of lunar dust for technology of particle removal from detector

In order to reduce the destruction of lunar dust electrostatic adhesion on detector and related equipment, technology of particle removal and charging model are researched. The technology of photoelectric dedusting is proposed. According to the particle orbit theory, current of photoelectron and electron are respectively obtained. Based on Maxwell energy distribution, the density distribution function of each particle is obtained. Then, charging model of lunar dust is setup. The model is solved by Runge-Kutta Method and charging regulation of lunar dust is obtained. Based on charging model, electrostatic adhesion force of nanoscale particles is got by discrete element software. At last, effect of solar radiation intensity on electrostatic adhesion is researched by discrete element software.

Design and research on asteroid anchor system based on DEM simulation

Asteroid detection has become an important part of the deep space exploration. The landing mechanism is easy to flow away from the asteroid surface because it is of microgravity and the rotation speed of the asteroid is high, thus the landing mechanism need to be fixed on the asteroid by anchor system after landing. Therefore, it is feasible to achieve a stable landing of asteroid lander, and provide ensurence for the subsequent scientific research. Based on the self-designed anchor system, this project carried on the simulation research of the following three aspects: 1) Penetration performance simulation: Discrete element simulation was used in the case of discrete soft geology and finite element simulation under continuous hard geology. Through this, the data of anchors penetrating depth, velocity, stress nephogram of structure and simulating animation were obtained in the condition of 0 angle of incidence. 2) Expansion performance simulation: Under the discrete soft geology, anchors expansion performance was analyzed under the action of explosive device in the case of 10 angle of incidence and 90m/s of incident velocity. 3) Adhesion performance simulation: Under the discrete soft geology, anchors adhesion performance was analyzed under 60N rope traction effect in the condition of 10 angle of incidence and 90m/s of incident velocity.