Virtual Simulation System with Path-following Control for Lunar Rovers Moving on Rough Terrain

Virtual simulation technology is of great importance for the teleoperation of lunar rovers during the exploration phase, as well as the design of locomotion systems, performance evaluation, and control strategy verification during the R&D phase. The currently used simulation methods for lunar rovers have several disadvantages such as poor fidelity for wheel-soil interaction mechanics, difficulty in simulating rough terrains, and high complexity making it difficult to realize mobility control in simulation systems. This paper presents an approach for the construction of a virtual simulation system that integrates the features of 3D modeling, wheel-soil interaction mechanics, dynamics analysis, mobility control, and visualization for lunar rovers. Wheel-soil interaction experiments are carried out to test the forces and moments acted on a lunar rover’s wheel by the soil with a vertical load of 80 N and slip ratios of 0, 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.6. The experimental results are referenced in order to set the parameters’ values for the PAC2002 tire model of the ADAMS/Tire module. In addition, the rough lunar terrain is simulated with 3DS Max software after analyzing its characteristics, and a data-transfer program is developed with Matlab to simulate the 3D reappearance of a lunar environment in ADAMS. The 3D model of a lunar rover is developed by using Pro/E software and is then imported into ADAMS. Finally, a virtual simulation system for lunar rovers is developed. A path-following control strategy based on slip compensation for a six-wheeled lunar rover prototype is researched. The controller is implemented by using Matlab/Simulink to carry out joint simulations with ADAMS. The designed virtual lunar rover could follow the planned path on a rough terrain. This paper can also provide a reference scheme for virtual simulation and performance analysis of rovers moving on rough lunar terrains.

The Mars rover subsurface penetrating radar onboard China's Mars 2020 mission

China's Mars probe,named Tianwen-1,including an orbiter and a landing rover,will be launched during the July-August 2020 Mars launch windows.Selected to be among the rover payloads is a Subsurface Penetrating Radar module(RoSPR).The main scientific objective of the RoSPR is to characterize the thickness and sub-layer distribution of the Martian soil.The RoSPR consists of two channels.The low frequency channel of the RoSPR will penetrate the Martian soil to depths of 10 to 100 m with a resolution of a few meters.The higher frequency channel will penetrate to a depth of 3 to 10 m with a resolution of a few centimeters.This paper describes the design of the instrument and some results of field experiments.

MOBILITY EVALUATION AND INNOVATION OF WHEELED SPACE ROVER

The mission and function requirements of lunar rover are analyzed, based on virtual prototype technology, the mobility evaluation theory and method for wheeled space rover are proposed, which provide a new way to study the innovative design of lunar rover. Based on the above theoretical system, an innovative lunar rover suspension system, which adopts a two-crank-slider mechanism, is proposed, and its dynamics model is created. Adopting virtual prototype technology, the ground adaptability, over-obstacle ability and driving placidity of the rover are evaluated in the virtual prototype software ADAMS. The analysis results show that the rover provides a high degree of mobility.

Design and Trafficability Study of Flexible Wheel for Planetary Exploration Rover

To reduce sending costs, a flexible wheel configuration is proposed. The wheel is made of titanium alloy （Ti-6Al-4V） in consideration of the planetary environment factors （i. e. strong radiation, big temperature differences, high vacuum）, and mass constraint of launch vehicle. The advantages of the proposed wheel involves the potential for： ① small sending volume and mass, ② large deployed area and volume to reduce wheel loading, ③ a damping effect to smooth motion on rough terrain. To study the trafficability and tractive performance of the wheel concept, the drawbar pull and driven torque were calculated based on simplified model of terramechanics formulations. The results show that the wheel possesses sufficient drawbar pull to negotiate all types of soil stratums listed in this contribution.

The penetrating depth analysis of Lunar Penetrating Radar onboard Chang＇e-3 rover

Lunar Penetrating Radar（LPR） has successfully been used to acquire a large amount of scientific data during its in-situ detection. The analysis of penetrating depth can help to determine whether the target is within the effective detection range and contribute to distinguishing useful echoes from noise.First, this study introduces two traditional methods, both based on a radar transmission equation, to calculate the penetrating depth. The only difference between the two methods is that the first method adopts system calibration parameters given in the calibration report and the second one uses high-voltage-off radar data. However, some prior knowledge and assumptions are needed in the radar equation and the accuracy of assumptions will directly influence the final results. Therefore, a new method termed the Correlation Coefficient Method（CCM） is provided in this study, which is only based on radar data without any a priori assumptions. The CCM can obtain the penetrating depth according to the different correlation between reflected echoes and noise. To be exact, there is a strong correlation in the useful reflected echoes and a random correlation in the noise between adjacent data traces. In addition, this method can acquire a variable penetrating depth along the profile of the rover, but only one single depth value can be obtained from traditional methods. Through a simulation, the CCM has been verified as an effective method to obtain penetration depth. The comparisons and analysis of the calculation results of these three methods are also implemented in this study. Finally, results show that the ultimate penetrating depth of Channel 1 and the estimated penetrating depth of Channel 2 range from 136.9 m to 165.5 m（ε_r = 6.6） and from 13.0 m to 17.5 m（ε_r = 2.3）, respectively.

Mechanical Analysis and Performance Optimization for the Lunar Rover’s Vane-Telescopic Walking Wheel

It is well-known that optimizing the wheel system of lunar rovers is essential.However,this is a difficult task due to the complex terrain of the moon and limited resources onboard lunar rovers.In this study,an experimental prototype was set up to analyze the existing mechanical design of a lunar rover and improve its performance.First,a new vane-telescopic walking wheel was proposed for the lunar rover with a positive and negative quadrangle suspension,considering the complex terrain of the moon.Next,the performance was optimized under the limitations of preserving the slope passage and minimizing power consumption.This was achieved via analysis of the wheel force during movement.Finally,the effectiveness of the proposed method was demonstrated by several simulation experiments.The newly designed wheel can protrude on demand and reduce energy consumption;it can be used as a reference for lunar rover development engineering in China.

Preface: The Chang'e-3 lander and rover mission to the Moon

The Chang＇e-3 （CE-3） lander and rover mission to the Moon was an in- termediate step in China＇s lunar exploration program, which will be followed by a sample return mission. The lander was equipped with a number of remote-sensing instruments including a pair of cameras （Landing Camera and Terrain Camera） for recording the landing process and surveying terrain, an extreme ultraviolet camera for monitoring activities in the Earth＇s plasmasphere, and a first-ever Moon-based ultravi- olet telescope for astronomical observations. The Yutu rover successfully carried out close-up observations with the Panoramic Camera, mineralogical investigations with the VIS-NIR Imaging Spectrometer, study of elemental abundances with the Active Particle-induced X-ray Spectrometer, and pioneering measurements of the lunar sub- surface with Lunar Penetrating Radar. This special issue provides a collection of key information on the instrumental designs, calibration methods and data processing pro- cedures used by these experiments with a perspective of facilitating further analyses of scientific data from CE-3 in preparation for future missions.

Experimental analysis on effect of grouser circumferential angle on motion performance of lunar rover wheel

To guide the design of grouser parameters for lunar rover wheel,the effect analysis of circumferential angle of grousers on motion performance of a rigid wheel was conducted in a laboratory single-wheel test bed with loose sand bin.All tests had been done at a free wheel sinkage.The circumferential angle was varied from 0°,5°,10°,15° to 20°.By the analysis and comparisons of tractive and steering performance between smooth wheels and wheels with different circumferential angle grousers,the results show that the drawbar pull(DP),driving torque(DT) and steering resistance moment(SRM) decrease slightly with the increasing circumferential angle.And chevron grousers are more beneficial to improve the tractive performance than herringbone grousers.In order to evaluate motion performance of wheels with grousers,the evaluation indexes of motion performance are introduced into the experimental results.The results reveal that the optimal circumferential angle is 0°,and the optimum value of wheel slip is 13% from the perspective of saving energy to the similar loose sand in the experiments.

Panoramic camera on the Yutu lunar rover of the Chang'e-3 mission

The Chang＇e-3 panoramic camera, which is composed of two cameras with identical functions, performances and interfaces, is installed on the lunar rover mast. It can acquire 3D images of the lunar surface based on the principle of binocular stereo vision. By rotating and pitching the mast, it can take several photographs of the patrol area. After stitching these images, panoramic images of the scenes will be obtained.Thus the topography and geomorphology of the patrol area and the impact crater, as well as the geological structure of the lunar surface, will be analyzed and studied.In addition, it can take color photographs of the lander using the Bayer color coding principle. It can observe the working status of the lander by switching between static image mode and dynamic video mode with automatic exposure time. The focal length of the lens on the panoramic camera is 50 mm and the field of view is 19.7？umination and viewing conditions, the largest signal-to-no×14.5？.Under the best illise ratio of the panoramic camera is 44 d B. Its static modulation transfer function is 0.33. A large number of ground testing experiments and on-orbit imaging results show that the functional interface of the panoramic camera works normally. The image quality of the panoramic camera is satisfactory. All the performance parameters of the panoramic camera satisfy the design requirements.

From the Rover Incident to the Nanjia Treaty―Whose Conflict? Whose Treaty?

This paper will focus on the Rover Incident of 1867 and the subsequent Nanjia Treaty;the main protagonists of the incident were the Kuraluts indigenous people;and different perspectives will be explored by integrating archaeological and historical data.The Rover Incident,a conflict between the Kuraluts and the United States,led to the Nanjia Treaty(Treaty of the Southern Headland),a reconciliation between the US and Tauketok,pre-eminent leader of 18 indigenous communities inhabiting this region.From the geographic location of the Kuraluts Village(Sheding Site),however,as well as from foreign coins and blue-and-white ceramics found as funerary objects inside stone coffins,it would seem that such contacts with the outside world were relatively frequent.Moreover,due to the aborigines’ability to make use of knowledge of the local geography and their military skills to defeat forces from the US’s naval fleet―which also indicates they were familiar with weaknesses in the military operations of foreign vessels―as a result,neither the US side nor Tauketok seemed to have any need to resort to the use of military force.

“关公”战“秦琼”AUDI A8 3.7 VS. LAND ROVER Range Rover

这场奇特的厮杀,多少有些"关公战秦琼"的味道。在中国几千年古代征战史中,有着"一寸长、一寸强;一寸短、一寸险"的说法。事实上,短兵器也确实不及长枪大刀妙趣横生威风八面、声名赫赫。然而尺有所知寸有所长,AUDIA83.7与RANGE ROVER V84.4,如同关云长的青龙偃月刀遇到了秦叔宝的瓦面金装镜,孰强孰弱?一试便知!

行者走天下——Land Rover Freelander 2

全新路虎Freelander2近日杀人了全球高档紧凑型SUV市场。这款携带众多先进技术的多功能路虎车．在北美市场被编为LR2．国内的名字就是神行者。“没有任何其他紧凑型4x4能够拥有如此的内部容量．”路虎公司总经理Phil Popham评价新车说．”神行者2重新定义了此类车型的标准．

新发现 Land Rover Discovery3

自发现这个系列出现之后,历经了15年的市场考验,其中只推出过一次大改款车型,除了强悍的越野能力之外。

美军ROVER V和AN-PRC-117G新型移动视频通信设备

美军2009年开始装备新型移动视频通信设备，包括两种新开发的轻型系统ROVER V和AN-PRC-117G，它能接受来自空中传感器平台的实时图像信息，允许步兵和特种作战部队通过战术通信和数据网络获取和共享视频流，从而将原有的指挥所系统和车载系统交付到连、班一级，其有较强的潜在应用能力和良好的应用前景，本文对这两种设备的技术、基本性能及其应用前景进行了介绍。

3D-Aided-Analysis Tool for Lunar Rover

3D-Aided-Analysis Tool （3DAAT） which is a virtual reality system is built up in this paper. 3DAAT is integrated with kinematics and dynamics model of rover as well as real lunar surface terrain mode. Methods of modeling which are proposed in this paper include constructing lunar surface, constructing 3D model of lander and rover, building up kinematic model of rover body. Photogrammetry technique and the remote sensing information are used to generate the terrain model of lunar surface. According to the implementation result, 3DAAT is an effective assist system for making exploration plan and analyzing the status of rover.

Range Rover Evoque

激动人心的全新五门版揽胜Evoque于当地时间11月17日在2010年洛杉矶车展全球首发。五门版Evoque完全忠实路虎LRX概念车的开创精神.

Configuration of the Chang'e 4 Lander and Rover Released

The Chang’e 4 lunar probe is planned to be launched this December from the Xichang Satellite Launch Center. It will be the first ever attempt of a soft landing and roving on the far side of the moon. The configuration of the Chang’e 4 lander and rover was unveiled at a ceremony for a naming contest of the rover held on August 15 in Beijing. The official name will be announced in October.

最快最强劲 LAND ROVER Range Rover Sport SVR

2014年8月,捷豹路虎公司（JLR）在美国圆石滩车展发布了全新路虎揽胜Sport SVR。这不仅是迄今为止速度最快、动力最强劲的路虎车型,也是捷豹路虎首款SVR高性能车型。四驱与越野才是路虎的核心价值所在,但最近路虎有点儿不务正业地搞起了性能版,发布了号称史上最快最强劲的揽胜Sport SVR高性能车型。量产SUV最快圈速路虎揽胜Sport SVR的百公里加速仅需4.7s,最高车速（电子限速）可达260km/h。并以8分14秒的成绩在德国纽博格林北环赛道创下量产SUV车型的最快单圈记录,彰显出这款车型的卓越性能和非凡实力。保时捷Macan Turbo今年初也挑战了该赛道,单圈时间为8分15秒。

LAND ROVER DEFFNDER X-TECH

Land Rover旗下的Defender车系，古朴风格与强悍的越野性能一直深入人心。方正的外形更是长久以来不变的经典元素。日前，Land Rover于比利时发表了融入更前卫风格。以黑白强烈对比为外观涂装的Defender X—Tech限量版车型。为Defender车系融八更时尚的生命气息。所以限量版车型除了车身颜色外，还通过搭配黑色车顶，大探照头灯及16寸黑色轮圈，让defender X—Tech呈现出强烈对比风格。

驾Land Rover体验OFF-ROAD的真谛

我们常说:路是人走出来的。语中充满着豪气干云的气概;但当真正尝试过身处荒野、前无去路的滋味后,方始明白要“走出一条路”着实并非易事。