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探月活动的英语作文Title: Exploring the Moon: Humanity's Gateway to the Cosmos。
The exploration of the Moon stands as one of the most significant milestones in human history. Since the first Moon landing in 1969, our fascination with Earth's natural satellite has only grown, leading to numerous exploratory missions and scientific endeavors. In this essay, we will delve into the importance of lunar exploration, its historical significance, current missions, and the future prospects it holds for humanity.Firstly, lunar exploration holds immense scientific value. The Moon serves as a natural laboratory, offering unique insights into the formation and evolution of celestial bodies. By studying its surface, geology, and mineral composition, scientists can unravel the mysteries of the early solar system and gain a better understanding of Earth's own history. Moreover, the Moon's lack ofatmosphere and magnetic field provides an ideal environment for astronomical observations, free from the distortions caused by Earth's atmosphere.Secondly, the exploration of the Moon has profound historical significance. The Apollo missions, particularly Apollo 11, marked the culmination of a fierce space race between the United States and the Soviet Union during the Cold War era. Neil Armstrong's iconic words, "That's one small step for man, one giant leap for mankind," echoed around the world, symbolizing humanity's capability to achieve the seemingly impossible. The successful lunar landings not only demonstrated technological prowess but also fostered a sense of unity and pride among people worldwide.Currently, several nations and space agencies are actively involved in lunar exploration. NASA's Artemis program aims to return humans to the Moon by the mid-2020s, with the objective of establishing a sustainable lunar presence. China's Chang'e missions have achievedsignificant milestones, including landing a rover on thefar side of the Moon, while the European Space Agency (ESA) and Roscosmos have plans for future lunar missions. Additionally, private companies like SpaceX and Blue Origin are developing their own lunar exploration initiatives, signaling a shift towards commercial space ventures.Looking ahead, the future of lunar exploration holds immense promise. Establishing a lunar base could serve as a stepping stone for future crewed missions to Mars and beyond. The Moon's proximity to Earth makes it an ideal testing ground for new technologies and systems requiredfor deep space travel. Furthermore, the utilization of lunar resources, such as water ice found in polar regions, could support long-term human presence and enable the production of rocket fuel and other essentials in space.In conclusion, the exploration of the Moon represents a testament to human curiosity, ingenuity, and ambition. From the pioneering days of the Apollo missions to the current era of international collaboration and commercial ventures, our journey to the Moon continues to inspire and captivate the imagination of people around the world. As we embark onthis new chapter of lunar exploration, we stand on the threshold of unlocking the secrets of the cosmos and expanding the horizons of human civilization.。
【阅读拓展】祝融号着陆火星，中国向航天梦迈向一大步5月15日，中国祝融号火星车成功着陆火星，这项航天任务技术难度非常高，是我国航天领域取得的一项重大突破。
近日，美国NPR发表了一篇相关文章，大家来了解一下吧。
China Lands On Mars In Major Advance For Its Space Ambitions China landed a spacecraft on Mars for the first time on Saturday, a technically challenging feat more difficult than a moon landing, in the latest step forward for its ambitious goals in space.Plans call for a rover to stay in the lander for a few days of diagnostic tests before rolling down a ramp to explore an area of Mars known as Utopia Planitia. It will join an American rover that arrived at the red planet in February.China’s first Mars landing follows its launch last month of the main section of what will be a permanent space station and a mission that brought back rocks from the moon late last year.“China has left a footprint on Mars for the first time, an important step for our country’s space exploration,” the official Xinhua News Agency said in announcing the landing on one of its social media accounts.The U.S. has had nine successful landings on Mars since 1976. The Soviet Union landed on the planet in 1971, but the mission failed after the craft stopped transmitting information soon after touchdown.A rover and a tiny helicopter from the American landing in February are currently exploring Mars. NASA expects the rover to collect its first sample in July for return to Earth in a decade.China has landed on the moon before but landing on Mars is a much more difficult undertaking. Spacecraft uses shields for protection from the searing heat of entering the Martian atmosphere, and uses both retro-rockets and parachutes to slow down enough to prevent a crash landing. The parachutes and rockets must be deployed at precise times to land at the designated spot. Only mini-retro rockets are required for a moon landing, and parachutes alone are sufficient for returning to Earth.Xinhua said the entry capsule entered the Mars atmosphere at an altitude of 125 kilometers(80 miles), initiating what it called “the riskiest phase of the whole mission.”A 200 square meter (2,150 square foot) parachute was deployed and later jettisoned, and then a retro-rocket was fired to slow the speed of the craft to almost zero, Xinhua said. The craft hovered about 100 meters (330 feet) above the surface to identify obstacles before touching down on four buffer legs.“Each step had only one chance, and the actions were closely linked. If there had been any flaw, the landing would have failed,”said Geng Yan, an official at the China National Space Administration, according to Xinhua.Touchdown was at 7:18 a.m. Beijing time (23:18 Friday GMT; 7:18 p.m. EDT), although more than an hour passed before ground controllers could confirm the landing was a success,Xinhua said. The rover had to open its solar panels and antenna, and then it took more than 17 minutes for its signals to traverse the distance between Mars and Earth.Chinese President Xi Jinping, in a congratulatory letter to the mission team, called the landing “an important step in our country’s interplanetary exploration journey, realizing the leap from Earth-moon to the planetary system and leaving the mark of the Chinese on Mars for the first time. ... The motherland and people will always remember your outstanding feats!”NASA Associate Administrator Thomas Zurbuchen tweeted his congratulations, saying, “Together with the global science community, I look forward to the important contributions this mission will make to humanity’s understanding of the Red Planet.”China’s Mars landing was the top trending topic on Weibo, a leading social media platform, as people expressed both excitement and pride.The Tianwen-1 spacecraft has been orbiting Mars since February, when it arrived after a 6 1/2-month journey from Earth. Xinhua described the mission as China’s first planetary exploration.The rover, named after the Chinese god of fire Zhurong, is expected to be deployed for 90 days to search for evidence of life. About the size of a small car, it has ground-penetrating radar, a laser, and sensors to gauge the atmosphere and magnetic sphere.China’s space program has proceeded in a more cautious manner than the U.S. and the Soviet Union during the height of their space race.The launch of the main module for China’s space station in April is the first of 11 planned missions to build and provision the station and send up a three-person crew by the end of next year. While the module was successfully launched, the uncontrolled return to Earth of the rocket drew international criticism including from NASA Administrator Bill Nelson.China has said it wants to land people on the moon and possibly build a scientific base there. No timeline has been released for these projects. A space plane is also reportedly under development.【词汇解析】1. land v.使（飞机）平稳着陆The pilot landed the plane safely.飞行员驾驶飞机安全着陆。
关于航空航天专业的英语词汇神舟六号Shenzhou VI (spacecraft)载人飞船manned spaceship/ spacecraft载人航天manned space flight多人多天太空飞行multi-manned and multi-day space flight载人航天计划manned space program航天飞机space shuttle无人飞船unmanned spaceship / spacecraft试验太空船Experimental Spacecraft多级火箭multistage rocket太空舱capsule返回式卫星recoverable satellite通信卫星communication satellite遥感卫星remote sensing satellite运载火箭carrier rocket; rocket launcher长征二号F运载火箭Long March II F carrier rocket有效载荷能力payload capability近地轨道low Earth orbit调整轨道fine-tune orbit绕地球飞行orbit the earth气象卫星weather satellite/meteorological satellite太阳同步轨道卫星satellite in Sun-synchronous orbit同步轨道卫星geosynchronous satellite轨道舱orbital module返回舱re-entry module推进舱propelling module指令舱command module服务舱service module登月舱lunar module发射台launch pad紧急供氧装置emergency oxygen apparatus空间物理探测space physics exploration国际空间站International Space Station太阳能电池板solar panel太空升降舱space elevator哈勃太空望远镜Hubble Space Telescope月球车lunar rover外太空outer space; deep space银河系Milky Way阿波罗号宇宙飞船Apollo中国空间技术研究院CAST(the Chinese Academy ofSpace Technology)中国航天局CNSA（China National Space Administration）美国航空航天管理局NASA(The National Aeronautics andSpace Administration)太空服space outfits(space suits）太空食物space food着陆区landing area主着陆场main landing field/ primary landing siteaccess flap 接口盖antenna 天线Apollo 阿波罗号宇宙飞船artificial satellite 人造卫星ascent stage 上升段astronaut 航天员capsule 太空舱carrier rocket; rocket launcher 运载火箭CAST(the Chinese Academy of Space Technology) 中国空间技术研究院CNSA（China National Space Administration）中国航天局command module 指令舱communication satellite 通信卫星descent stage 下降段directional antenna 定向天线emergency oxygen apparatus 应急供氧装置Experimental Spacecraft 试验太空船fine-tune orbit 调整轨道geosynchronous satellite 同步轨道卫星hatch 舱口Hubble Space Telescope 哈勃太空望远镜International Space Station 国际空间站ladder 扶梯landing area 着陆区landing pad 着陆架launch a satellite 发射卫星launch pad 发射台life support system 生命维持系统LM-maneuvering rockets 登月舱机动火箭Long March II F carrier rocket 长征二号F运载火箭low Earth orbit 近地轨道lunar module 登月舱lunar rover 月球车main landing field/ primary landing site 主着陆场manned space 载人航天计划manned space flight 载人航天manned spaceship/ spacecraft 载人飞船Milky Way 银河系multi-manned and multi-day spaceflight 多人多天太空飞行multistage rocket 多级火箭multistage rocket 多级火箭NASA(The National Aeronautics and Space Administration)美国航空航天管理局nozzle of the main engine 主发动机喷嘴orbit 轨道orbit the earth 绕地球飞行orbital module 轨道舱outer space; deep space 外太空payload capability 有效载荷能力propelling module 推进舱recoverable satellite 返回式卫星re-entry module 返回舱remote sensing satellite 遥感卫星satellite in Sun-synchronous orbit 太阳同步轨道卫星second stage 第二级service module 服务舱solar cell 太阳电池solar panel 太阳能电池板space elevator 太空升降舱space food 太空食物space outfits（space suits，gloves，boots，helmet etc.）太空服space physics exploration 空间物理探测space shuttle 航天飞机space suit 航天服spacecraft 航天器Telstar 通信卫星third stage 第三级unmanned spaceship / spacecraft 无人飞船weather satellite; meteorological satellite 气象卫星句子翻译：1992年8月9日，长征二号丁运载火箭在酒泉卫星发射中心成功发射第十三颗返回式卫星。
I课肓达标检测丨（建议用时：35分钟）I •阅读理解A（2020 •大连高三双基测试）ln Mark Turin ' s article "Protecting Our PublicSpaces”in issue 14, he claims that “ all graffiti（涂鸦）isvan dalism（故意破坏财物的行为）,pure and simple, and offers no ben efitto our public spaces ” . I would like to point out that many people believe thatgraffiti is an art form that can ben efit our public spaces just as much as sculptures, fountains, or other more accepted art forms.People who object to graffiti usually do so more because of where it is, not what it is. They argue that post ing graffiti in public places is con sidered an illegal act of property damage. But the locati on of such graffiti should not preve nt the images themselves from being con sidered real art.I would argue that graffiti is the most important public art form. Spray paint is a medium unlike any other. Through graffiti, the entire world has become a canvas（画布）.These works of art dott ing the urba n Ian dscape are available, free of charge, to every one who passes by.To be clear, I do not consider random words or names sprayed on stop sig ns to be art. Plenty of graffiti is just vandalism, pure and simple. However, there is also graffiti that is breathtaking in its complex detail, its realism, or its creativity. It takes great tale nt to create such in volved desig ns with spray paint. Are these creators not artists just because they use a can of spray paint in stead of a pain tbrush?To declare that all graffiti is vandalism, and nothing more, is an overly simplistic statement. Furthermore, graffiti is not going any where, so we might as well find a way to live with it and enjoy its ben efits. One opti on could be to make a perce ntage of public spaces ope n to graffiti artists. By doing this, the public might feel like part owners of these works of art, rather tha n just the victims of a crime.【解题导语】本文是一篇议论文。
语法填空高频话题(航天科技与科学)1.（2023年湖南省岳阳市岳阳县新高考试题）阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。
China’s Mars rover (火星车) Zhurong is currently in safe mode as it waits out a Martian dust storm and it may remain in safe mode until 1 end of 2022.Zhurong landed on Mars a year ago; from then on, the rover has recorded video and audio from the largest recognized impact basin 2 (name) Utopia Planitia. Zhurong’s initial mission was just 90 days but since then the rover 3 (continue) to study the Martian surface and atmosphere. The rover was also forced into a safe mode in September 2021, when Earth-based space agencies broke off communication with the Martian spacecraft (航天器). Now, the issue is with local extreme weather.It has 4 (recent) become winter in Utopia Planitia and the 5 (condition) are severe even without the dust storm. The China National Space Administration (CNSA) said that the temperature 6 (different) between day and night on Mars is huge. Utopia Planitia’s storms can be deadly to the Martian spacecraft 7 rely on solar power; the storms can block out sunlight for months. But Zhurong is expected 8 (handle) the ongoing storm with 9 (relate) ease. Meanwhile, CNSA’s Tianwen-1 Mars orbiter will continue to keep track 10 the Martian atmosphere for any changes in the Red Planet’s weather.2.（2023年江苏省扬州市广陵区扬州中学高三试题）阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。
月球小车实验计划步骤英文回答：The Lunar Rover Mission Experiment Plan.Lunar Rover Mission Experiment Plan.Objective: To design and build a lunar rover capable of navigating and conducting experiments on the surface of the Moon.Materials:Aluminum chassis.Electric motors.Wheels.Solar panels.Batteries.Camera.Sensors.Procedure:1. Design the rover: The first step is to design the rover. The rover should be lightweight and durable, and it should be able to navigate the rough terrain of the Moon. The rover should also be able to carry a payload of scientific instruments.2. Build the rover: Once the rover has been designed, it can be built. The rover will be assembled using aluminum chassis, electric motors, wheels, solar panels, batteries, a camera, and sensors.3. Test the rover: Once the rover has been built, it should be tested. The rover will be tested in a simulatedlunar environment to ensure that it is functioning properly.4. Deploy the rover: Once the rover has been tested, it can be deployed to the Moon. The rover will be launched ona rocket and landed on the surface of the Moon.5. Conduct experiments: Once the rover has been deployed, it can begin conducting experiments. The roverwill use its camera and sensors to collect data about the lunar surface. The rover will also collect samples of lunar rocks and dust.Expected Results:The expected results of the lunar rover mission experiment are as follows:The rover will successfully navigate the lunar surface.The rover will successfully conduct experiments on the lunar surface.The rover will collect valuable data about the lunar surface.The rover will collect valuable samples of lunar rocks and dust.Conclusion:The lunar rover mission experiment is a challenging but exciting endeavor. The experiment will help us to learn more about the Moon and its history. The experiment will also help us to develop new technologies for future space exploration.中文回答：月球车实验计划。
航天知识英语竞赛试题及答案一、选择题1. Who is considered the father of modern rocketry?A. Robert H. GoddardB. Yuri GagarinC. Neil ArmstrongD. Wernher von BraunAnswer: A. Robert H. Goddard2. The International Space Station (ISS) orbits the Earth approximately how many times a day?A. 15B. 16C. 24D. 30Answer: B. 163. Which space mission successfully landed on Mars and sent back the first color pictures of the planet's surface?A. Viking 1B. Apollo 11C. Mars PathfinderD. Spirit RoverAnswer: A. Viking 14. What is the name of the first artificial satellitelaunched by the Soviet Union?A. Sputnik 1B. Explorer 1C. TelstarD. VanguardAnswer: A. Sputnik 15. Who was the first human to walk on the Moon?A. Yuri GagarinB. Neil ArmstrongC. Buzz AldrinD. Alan ShepardAnswer: B. Neil Armstrong二、填空题6. The first human-made object to reach the Moon was ________, launched by the United States in 1959.Answer: Pioneer 47. The Apollo program was a series of ________ lunar missions carried out by the United States' National Aeronautics and Space Administration (NASA).Answer: manned8. The Hubble Space Telescope was launched into space by the Space Shuttle ________ in 1990.Answer: Discovery9. The Mars rover ________ was the first rover to drill into Mars' surface to collect samples.Answer: Curiosity10. The first woman to walk in space was ________, a Soviet cosmonaut.Answer: Svetlana Savitskaya三、简答题11. What is the purpose of a space telescope, and why is it advantageous to have them in space rather than on Earth?Answer: A space telescope is designed to observe distant objects in space without the distortion caused by Earth's atmosphere. The main advantage of having a space telescope is that it can capture clearer images and observe parts of the electromagnetic spectrum that are not visible from the ground due to atmospheric interference.12. Explain the concept of a geostationary orbit and its significance.Answer: A geostationary orbit is a circular orbit in Earth's equatorial plane at an altitude of approximately35,786 kilometers (22,236 miles). Satellites in geostationary orbit have an orbital period equal to the Earth's rotation period, which means they appear to be stationary in the sky. This is significant for communication and weather monitoringsatellites, as they can maintain a constant position relative to the Earth's surface.结束语This set of questions is designed to test your knowledge of space exploration and its history. We hope it has been a fun and educational experience for you. Keep exploring the cosmos, both in your studies and in your imagination!。
VOA慢速：为探索月球而建造的新太空飞船An American company has presented a new space vehicle built to explore the moon.一家美国公司展示了一种为探索月球而建造的新型航天器。
California-based Venturi Astrolab uncovered its working model of the vehicle last week.总部位于加州的文丘里天体实验室上周公布了该航天器的工作模型。
The explorer, or rover, is called FLEX.这个探测器或漫游者被称为FLEX。
Astrolab officials say the four-wheeled rover was designed to be sent to the moon by the American space agency NASA.天体实验室的官员说，这个四轮月球车是由美国宇航局设计用来发射到月球的。
FLEX was developed to transport astronauts and cargo and support a series of lunar activities and experiments.FLEX的开发是为了运送宇航员和货物，并支持一系列的月球活动和实验。
If NASA chooses to use the vehicle, it will become part of the Artemis program.如果NASA选择使用这个飞行器，它将成为阿尔特弥斯计划的一部分。
That program aims to return humans to the moon as early as 2025.该计划的目标是最早在2025年让人类重返月球。
It also calls for establishing a long-term base on the moon that could one day launch astronauts to Mars.它还要求在月球上建立一个长期基地，有朝一日可以把宇航员送上火星。
与“嫦娥一号”绕月卫星有关的词汇其它航天词汇绕月卫星 circumlunar satellite嫦娥1号 Chang'e-1 lunar probe; Chang'e-1 lunar satellite月球探测卫星 lunar probe; lunar exploration satellite; lunar orbiter发射台 launch pad发射窗口 launch window （“发射窗口”是指运载火箭发射航天器选定的一个比较合适的时间范围，即允许运载火箭发射的时间范围。
）燃料加注 fuel adding长征三号甲运载火箭 Long March 3A launch vehicle; LM-3A launch vehicle发射区 launch site地月转移轨道 Earth-moon transfer orbit现场观摩发射 watch the launch at the site月球探测工程 moon exploration project; moon probe project液氧 liquid oxygen液氢 liquid hydrogen点火 ignition发射前的最后检查和测试 pre-launch tests中国国家航天局 China National Space Administration (CNSA)卫星同发射装置分离进入指定轨道：The satellite separated from the launch vehicle and entered the projected orbit; The satellite was released from the launcher upper stage and entered the projected orbit收集月球表面数据 collect lunar surface data拍摄和传送地球照片 capture and relay pictures of Earth发射升空 liftoff; blastoff; take off偏离轨道 veer off course; deviate from course月球表面化学元素和矿物质分布 distribution of chemical elements and minerals on lunar surface地形和地表结构 topographical and surface structures月球的重力场和环境 gravity field and environment of the moon主力火箭 main rockets极轨道 polar orbit立体摄像机 stereo camera绘制月球表面的三维图像 map three-dimensional images of the lunar surface观测装置 observation instruments探测器的工作寿命Chang’e-1 w ill remain in position for about one year. Chang’e-1 will orbit the moon for one year until it runs out of fuel.科学目标：获取月球表面三维影像，分析月球表面有用元素及物质类型的含量和分布，探测月壤特性，探测40万公里间的地月空间环境。
A STEWART PLATFORM LUNAR ROVERRoger Bostelman1, James Albus,Karl Murphy, Tsung-Ming Tsai, Ed AmatucciAbstractof the National Institute of Standards and Technology (NIST) to address the needs of NASA researchers. The NIST robot, called ROBOCRANE, has three-pairs of rigged legs instead of actuators to create a gantry. The legs are joined in a Stewart Platform configuration providing a means for canceling out rotations normally present in gantry structures. Therefore, the frame can be made lightweight and yet, withstand high forces and torques limited mainly by the compression/tension strength of each leg. Each of three six foot legs rotates about an upper triangle to provide stable, yet flexible three-point ground contact. This makes an ideal configuration for attaching vehicles to the gantry for mobilization.The unique structure of the NIST Robocrane provides a powerful platform which can accommodate the execution of diversified tasks due to its exceptionally high payload to vehicle mass ratio, ease of payload manipulation, outstanding mobility characteristics (tested on a smooth surface), and compact packaging for transport.A 2-meter and a 6-meter version of the Robocrane have been built and critical performance characteristics and control methods analyzed. This robot, being able to rotate the legs independently about the upper triangle, is well suited for traveling over rough terrain and doing work such as construction or soil sampling on other planets. In 1992, the 2-meter Robocrane was exhibited at the Lunar Rover Expo, at the National Air and Space Museum, Washington, D. C.Introductiondesign utilizing six cables to suspend a load platform was first developed by the National Institute of Standards and Technology (NIST) in the early 1980's. A NIST program on robot crane technology, sponsored by Advanced Research Projects Agency (ARPA), produced the design, development and testing of three different sized prototypes to determine the performance characteristics of this proposed robot crane design. A description of the overall ARPA program and the results of this research are presented in [Dagalakis, 1989]. Initial testing of these prototypes showed that this design results in a stiff load platform [Dagalakis, 1989; Unger, 1988]. This platform (see figure 1) can be used in typical crane operations, or1 Electronics Engineer, Robot Systems Division, National Institute of Standards and Technology, Bldg. 220, Rm. B127, Gaithersburg, MD 20899as a robot base, or a combination of both. Applications of this new crane design are illustrated: in [Albus, 1993] for the construction industry and in [Bostelman, 1993] for the subsea arena. As part of the research being done on the Robocrane, the authors have applied this unique system design to a Stewart Platform type mobile robot with potential lunar capabilities.The objective of this paper is to describe the 2-meter Robocrane, including: the mechanical structure, the electrical components, computer and it's interface to sensors, the mobility control algorithm, the future lunar configuration and deployment scheme and various lunar applications.A number of advantages of the Robocrane as applied to potential lunar rover applications are: rigid support and precise maneuverability of large loads, remote positioning of tools and equipment, execution of precise motions with tools/equipment to accomplish complex tasks, high lift-to-weight ratio, resistance to environmental perturbations (i.e.. wind, etc.), accurate control of loads via remote control, long-range mobility, and self-deployment.A three wheeled vehicle was chosen over a four wheeled for several reasons:1. Simplicity -- A rigid three wheeled vehicle will conform to an uneven surface. A four wheeled vehicle must have independent suspension to conform to an uneven surface.2. Weight -- A three wheeled vehicle must be larger than a four wheeled vehicle to have the same stability against tip-over. However, the additional weight required for a fourth wheel with its suspension and drive train is greater than the additional weight required for the larger frame.3. Stability -- A three wheeled vehicle is more stable against tip-over than a four wheeled vehicle of the same weight, if one wheel is kept down-hill.Figure 1 - Photograph of the 2 meter ROBOCRANE Model with Camera Platform.This design maximizes the wheel base for stability against tip-over, maximizes the wheel diameter to enhance traversibility, and maximizes the payload/vehicle weight ratio for mission effectiveness. With coordination of the three wheels and a work platform, the robot can change it's configuration enough to route through underpasses and straddle trenches. By changing the gantry shape and/or maneuvering the work platform, the robot can shift it's center-of-gravity to maintain equal ground pressure and to aid in hill-climbs.This paper includes preliminary design and development of a Stewart Platform Lunar Rover, mobility control of the flexible structure, the deployment scheme from the Artemis lander, and a conclusion followed by a list of references for the paper.Preliminary Design and Developmentto study the mobility and capabilities of such a system. The main components of the model are the mobile gantry, the work platform, the control computer and electronics, and the communications.The mobile gantry consists of 2 m tubular aluminum frame components joined in the shape of an octahedron. The legs are triangles and attach to an upper triangle with loosely fit U-bolts to provide a hinge for the leg. Provided no leg-to-leg connections are made, the legs are free to rotate more than 180° with the vertical. Since small vehicles were chosen to show a construction application, truss cables and springs were attached to the legs and upper triangle to eliminate vehicle side loads. Each of three vehicles is attached to each leg via a universal joint and a rotary joint. The "U-joint" allows each vehicle to independently conform to the terrain while the rotary joint allows each vehicle to rotate with respect to the gantry. The U and rotary joints are simply bolted to the tubular frame.A rotary potentiometer is housed within each rotary joint and attached between the gantry and the vehicle. The rotary pot. is used to measure the vehicle angle with respect to it's corresponding leg. A linear potentiometer is attached between each pair of adjacent legs and near the top triangle. Therefore, large leg motions can be sensed with a small linear pot. which provides direct leg separation distance between two adjacent legs. Only these six sensors are used as gantry geometry feedback to the computer.The gantry houses a cable-driven Stewart Platform that has a work volume limited to cable length, work platform size and upper triangle size. A pair of winches are mounted to each leg near the vehicles. The mechanical winch cables follow the leg up to a pulley supported by the upper triangle and down to the work platform.Each vehicle houses power amplifiers, and relay circuitry to power both the vehicles and the winches. The vehicle tracks are individually powered by a separate amplifier that can be instantaneously switched to winch control by reconfiguring the amplifier resistor network. Power for the system is provided by a battery stack located on each leg.The computer is mounted on the work platform which, provides additional weight on the platform, and provides increased platform stability while the robot is driving. Electrical cables from the computer and to all sensors and amplifiers are supported vertically before being disbursed to add weight symmetrically to the robot. Tools are attached to the work platform. Depending on what is suspended from its work platform, Robocrane can perform a variety of lunar tasks. Examples are: cutting, lifting and positioning, core sampling and drilling, and gripping, and inspection.By attaching stereo vision and pan, tilt, and zoom capabilities to a camera platform, Robocrane makes a large exploratory robot. Fixing cameras to the work platform allows inspection at close range to the work sight.Mobility Control of the Flexible Structure each leg, and controlled by an onboard computer. The operator, using a rotary pot and a joystick, commands rotational velocity and translational velocity of the Robocrane. The controller measures the leg spacing and orientation of each tank with respect to the Robocrane. Each tank tread velocity is computed so that the Robocrane moves at the commanded velocity and rotational rate while maintaining proper leg spacing. The control is a two step process. First we assume each tank can move in any direction and compute a translational velocity that meets the operator commands and maintains leg spacing. Second, we compute tread velocity by relating the tank’s lateral velocity to a rotational velocity. The algorithm requires only two gains. One gain relates shape error into velocity and the other gain relates a tank's lateral velocity into rotational velocity. The first step is to compute a desired translational velocity for each tank, v 1, v 2, and v 3. The tank may or may not be able to move in the desired direction but that is left until the second step. Figure 2 [left] shows an imaginary triangle formed by the location of the three tanks. The length of each side is the desired length plus an error term. The operator commands a rotational and translational velocity, ωcmd and V cmd ,for the structure represented in the coordinate frame x–y. A coordinate frame, ov-in, is attached to each vertex.V ω= K rot V latVV i 2ω = L desired Figure 2 - [left] Imaginary triangle formed by the three vehicles used to compute velocities, rotations, and vehicle spacing. [right] Each tank can move forward and can rotate but cannot move laterally. Thus, the rotational rate is set proportional to lateral velocity in order to head the tank in the desired velocity direction.The desired velocity for each tank is the sum of the velocities that translates the Robocrane at the operator’s commanded velocity, rotates the Robocrane at the commanded rate, and maintains the proper tank spacing. To translate the crane, each tank should move at the commanded velocity, v cmd , taking into account the different coordinate frames. To rotate the crane, each tank should move assuming rigid body rotation. For computational simplicity, we assumed small deviations from anequilateral triangle. Thus, to rotate at the commanded rate, each tank should move in its ov direction with a velocity:v ov = [L desired / 2cos(30°)] ωcmd .Finally a velocity must be added that moves the tanks relative to each other in order to maintain the desired spacing. This feedback portion of the algorithm accounts for tread slippage, terrain aberrations, and inaccuracies in the control model. Each vehicle is commanded a velocity proportional to the spacing errors, e ij , in a direction that drives the errors to zero. Each tank attempts to correct the two adjacent sides of the triangle. For tank 2, consider the case where tanks 1 and 3 are fixed and that the lengths L 12 and L 23 are directly controllable. For a first order response the change in length is set proportional to the error:dL 12dt= – K shape e 12and similarly for L 23 . However, we do not have direct control over the lengths but rather we control the tanks’ velocity. Therefore, shown in the equation below, the Jacobean is used to transform the changes in the length of the triangle’s sides to changes in the Cartesian position of the tank. The commanded velocity for tank 2becomes:V ov V in = ∂ov ∂L 12 L 23∂ov ∂L 23 L 12∂in ∂L 12 L 23∂in ∂L 23 L 12 dL 12dtdL 23dtAgain, for computational simplicity, we assumed small deviations from an equilateral triangle. Thus to maintain the shape, the desired velocity of tank 2 in the ov-in coordinate frame become:V ov = K shape e 23 – e 12V in = K shape 2 cos 30°e 12 + e 23Similar equations are used for tanks 1 and 3. Note that each tank attempts to maintain the length of both of the adjacent sides of the triangle. If the tanks could move in the desired direction the side lengths would be adjusted at a rate proportional to twice K shape .For the second step the three velocities are added together for each tank yielding a desired velocity which, in most cases, will not be pointing in the same direction that the tank is heading. Each tank can move forward and backwards by driving the two treads in the same direction and each tank can rotate by driving the treads in opposite directions. However, the tank normally cannot move in the direction of the desired velocity (see Figure 2 [right]). One method to account for the misalignment between the heading and desired velocity would be to have the tanks stop, rotate to the proper heading, and then drive at the desired speed. The obvious problem with this is that the tanks would have to start and stop whenever the operator changed the commanded velocity or when errors occurred in tank spacing.Instead the lateral part of the desired velocity is converted into a rotational rate, ω, that is proportional to the lateral velocity. The tread velocities are:V left = V forward + r K rot V latV right = V forward – r K rot V latIf the tank is moving backwards, V forward is negative, then the sign on the rotation is flipped so that the rear, rather than the front, of the tank turns in the direction of V lat. Finally, if any tread velocity is greater than its maximum, then all the tread velocities are scaled proportionally to keep tread velocities within operational bounds.Proposed Robocrane for Artemis DeploymentA NIST/Arizona University (AU) team proposed [Albus, 1992] a vehicle structure for a NASA Artemis lunar exploration mission that is very similar to the NIST 2-meter model ROBOCRANE except that it uses large diameter bicycle type wheels instead of tracked vehicles. The NIST/AU design would support a work platform carrying instruments by six cables from six winches located at the three vertices of the centerFigure 3 - Photo of a model of the proposed Stewart Platform Lunar Rover. triangle of the frame. The proposed three-wheeled lunar rover is to have a mass of 65 kg, including the vehicle and 15 kg of experiments and platform weight. This allows an increased payload of much more than the 15 kg payload being carried once deployed at its destination. The work platform would also support a mast (see figure 3) with three cables attached to its top. At the very top of the mast is a pan/tilt head supporting a narrow beam antenna that is kept pointed toward the Earth for wide-bandcommunications. Near the top of the mast, under the antenna dish, a suite of cameras is mounted for navigation, mapping, and driving.The lengths of the three mast cables are controlled by three additional winches to put the mast in compression and thereby maintain all nine cables in tension at all times. This enables the work platform to be moved outside the footprint of the vehicle where it can perform experiments on vertical surfaces of boulders or cliffs.The three additional winches applying forces between the gantry and the platform can also be used to exert sufficient downward force on the work platform to lift the entire vehicle off the ground. Additional force may be needed by attaching a work platform tool and inserting it into a surface, thereby lifting the vehicle from the work platform to apply additional weight. This capability is also used during vehicle deployment from the Artemis lander.The vehicle will be folded up so as to fit on top of the lander inside a 2 1/2 meter diameter nose cone. Each of the three wheels will fold up inside its triangular wheel support structure, and the wheel support structure folds down so that it is in a vertical plane. When in their stowed position, the wheel forks are upside down with their tops resting on the top of the lander. During launch and transit, six cables between the vehicle and the work platform are tensioned so as to hold the vehicle firmly against the top of the lander.Figure 4 - Conceptual drawings of the deployment sequence from the Artemis Lander. (Cylindrical payload would be attached to the lander; cables not shownfor clarity).The work platform rests in the center on top of the lander, attached to a ramp that slides and pivots during the deployment phase. The deployment sequence consists ofa series of six steps:1. The six cables holding the vehicle in its stowed position are jettisoned.2. The three mast cables are winched in, and the six cables attached to the work platform are let out under position control, so that the vehicle is lifted off the lander and supported in a stable configuration on the work platform.3. A set of cables connecting the wheel axles to the lander are winched in while an opposing set connecting the wheel axles to the vehicle are let out. This causes thewheels to swing down and the wheel support structures swing out. The set of cables connecting the tops of the wheel forks to the top of the mast are winched in so that the wheels drop down and the wheel support structures swing up into deployed position.4. The cables attached to the wheel axles are jettisoned and the structural support cables attached to the top of the wheel forks are winched taut. At this point the vehicle's wheels are fully deployed and ready for launch.5. The six cables attached to the work platform are winched in while tension is maintained by the three mast cables, so as to lower the vehicle.6. The sliding ramp on which the work platform is resting slides to the side of the lander top.7. The sliding ramp slides out over the edge of the lander and tilts so as to lower the vehicle to the ground. Once all three wheels are on the ground, the work platform is then free to roll away from the lander to begin its exploration mission.The Phase One deliverables from the NIST/AU proposal are: to define mission and sub-system specifications for range, power, weight, communications, computing speed and memory, etc.; develop alternative designs of the vehicle on a CAD system; design and produce a full-scale physical mockup of the proposed vehicle and demonstrate technical feasibility of the vehicle design; design and produce a full-scale working prototype of the work platform, tool set, and simulated instrument payload, mounted on a stationary mockup of the vehicle; produce a report which describes the results of the Phase One study, and recommendations for Phase Two.Conclusionsmobile, stable, and versatile tool for doing a variety of required tasks. Two feasibility models have been developed at NIST. Arizona University and NIST have produced a three phase proposal incorporating a deployment scheme, vehicle designs, and methods for:1. Navigation and payload free-space manipulation accomplished through remote supervisory control based on the information obtained through cameras2. Force controlled payload and tool contact manipulation accomplished through virtual reality teleoperation augmented by local reflexive sensory-interactive control3. Computer-aided remote driving technology employed for driving, with collision and tip-over avoidance procedures activated by local reflexive sensory-interactive control. Additionally, computations of rover power while traversing various simulated terrains and rover component failures are to be addressed.Acknowledgementsworking system for demonstration in a short period of time: Adam Jacoff -mechanical drive system design and development, Hoosh Abrishamian - radio control electronics design and development, Charles Giauque - mechanical technology, Wendell Wallace - electronic technology, Ken Goodwin - NIST/AU team proposal.ReferencesH., and Bostelman, R. V., "Robot Crane Technology Program -- Final Report," NIST Technical Note 1267, National Institute of Standards and Technology, Gaithersburg, MD, July 1989.[2]Dagalakis, N. G., Albus, J. S., Wang, B. L., Unger, J., and Lee, J. D., "Stiffness Study of a Parallel Link Robot Crane for Shipbuilding Applications," Transactions of the ASME Journal of Offshore Mechanics and Artic Engineering, Vol. 111, No. 3, pp.183-193, 1989.[3] Unger, J., and Dagalakis, N. G., "Optimum Stiffness Study for a Parallel Link Robot Crane Under Horizontal Force," Proceedings of the Second International Symposium on Robotics and Manufacturing Research, Education and Applications, Albuquerque, NM, November 16-18, 1988.[4]Albus, J. S., Bostelman, R. V., Dagalakis, N. G., "The NIST ROBOCRANE," Journal of Robotic Systems, 10 (5), 709-724, 1993.[5]Bostelman, R.B., Albus, J.S., "Stability of an Underwater Work Platform Suspended from an Unstable Reference," to be published in the Proc. of Oceans '93, Engineering in Harmony with the Ocean, October, 1993.[6] Albus, J.S, Schooley, L.C., "Research Proposal for An Intelligent Robotic Vehicle for Lunar Resource Assessment," presented at the Lunar Rover/Mobility Workshop, Houston, TX, April 1992, and at the 3rd Space Exploration Initiative Technical Exchange Meeting, May 1992.。
