Robotic Rover Research Articles

Interaction Mechanics Model for Rigid Driving Wheels of Planetary Rovers Moving on Sandy Terrain with Consideration of Multiple Physical Effects

Predicting wheel‐terrain interaction with semiempirical models is of substantial importance for developing planetary wheeled mobile robots (rovers). Primarily geared toward the design of manned terrestrial vehicles, conventional terramechanics models do not provide the sufficient fidelity required for application on autonomous planetary rovers. To develop a high‐fidelity interaction mechanics model, in this study the physical effects of wheel lug, slip sinkage, wheel dimension, and load are analyzed based on experimental results, including wheel sinkage, drawbar pull, normal force, and moment, which are measured on a single‐wheel test bed. The mechanism of lug‐terrain interaction is investigated systematically to clarify the principle of increasing shear stress, conditions of forming successive shearing among adjacent lugs, and the influence on shear displacement of soil. A mathematical model for predicting the concentrated forces and torque of rigid wheels with lugs for planetary rovers moving on sandy terrain is derived by integrating the improved models of normal and shearing stress distributions. In addition to the wheel parameters, terrain parameters, and motion state variables, wheel‐terrain interaction parameters, such as the linear varying sinkage exponent, the soil displacement radius, and load effect parameters, were proposed and explicitly included in the model. In the single‐wheel experiments, the slip ratio was increased approximately from 0.05 to 0.6, and the relative errors of the predicted results using the proposed model are less than 10% for all the wheels when compared with the experimental data. The proposed model has been used in the simulation of a four‐wheeled rover, and its effectiveness is evaluated by comparing the simulation results with experimental results.

Lithium-Rich NMC Cathodes and Si-C Anodes in Low Flammability Li-Ion Battery Electrolytes

Li-ion batteries were successfully employed in our Mars planetary surface missions, e.g., robotic Mars Rovers, Spirit, Opportunity and Curiosity. However, the future space missions involve human exploration and demand further advances both in energy densities and safety. For example, astronaut Extra Vehicular Activity requires safer batteries with a specific energy in excess of 300 Wh/kg, albeit with moderate cycle life. We have therefore been developing advanced cell components, i.e., high specific capacity cathodes and anodes for improving the specific energy and also low-flammability electrolytes for enhancing safety. Our cathode materials belong to the class of Li-rich, layered-layered composites (of Li2MnO3 and LiMO2)1. Over the last few years, we have: i) optimized their compositions and modified synthesis to maximize specific capacities and tap densities, ii) identified new simpler synthetic methods, based on high energy ball–milling2 and molten salt fluxes iii) and developed new surface coatings, e.g., AlPO4to improve interfacial and cyclic stability. To augment the in-house development, we have also evaluated materials from commercial materials suppliers. A critical component to the performance of the high-energy cathode and anode materials is electrolyte, especially due to the high cathode potentials resulting in electrolyte oxidation and the need to passivate anode for kinetic stability. Further, to improve safety, we adopted low-flammability electrolytes with suitable non-flammable co-solvents, and/or flame retardant additives, e.g., triphenyl phosphate.3 Also, to improve the interfacial stability, especially both cathode and anode, various electrolyte additives, such as vinylene carbonate and lithium bis(oxalate) borate were studied in addition to the surface coatings on cathode particles. We will present the performance of the AlPO4-coated Li-rich NMC cathode against MPG111 anode in different low-flammability electrolytes . Some of these electrolytes have also shown excellent performance in 4V systems, giving comparable cycle life in prototype cells . In this paper, we will present the performance of some of our recent Li-rich NMC cathode materials and Si-C anode composite anodes in conjunction with various low flammability electrolytes. The effect of electrolyte, as well surface coating, on the cathode activation process as well as the (transition) metal leaching from the cathode will be examined. Finally, the performance of the low flammability electrolyte in large-format prototype cells will be presented. Acknowledgments The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA) and was supported by the Office of Chief Technologist’s Advanced Space Power Systems project. References J. R. Dahn et al, J. Electrochem. Soc., 149, A778, 2002; K. Amine et al, Electrochem. Solid-State Lett., 6, A183, 2003; M. M. Thackeray et al, Electrochem. Comm., 9, 787 (2007); A. Manthiram et al, J. Electrochem. Soc., 155, A635 (2008).W. C. West, J. Soler, and B. V. Ratnakumar, J. Power Sources (in press).M.C. Smart, F. C. Krause, C. Hwang, W. C. West, J. Soler, G. K. S. Prakash, and B. V. Ratnakumar, 220th ECS Fall Meeting, Boston, MA, Oct. 2012; 222nd ECS Fall Meeting, San Francisco, CA , Oct 24-30 (2013).

The Cyborg Astrobiologist: matching of prior textures by image compression for geological mapping and novelty detection

AbstractWe describe an image-comparison technique of Heidemann and Ritter (2008a, b), which uses image compression, and is capable of: (i) detecting novel textures in a series of images, as well as of: (ii) alerting the user to the similarity of a new image to a previously observed texture. This image-comparison technique has been implemented and tested using our Astrobiology Phone-cam system, which employs Bluetooth communication to send images to a local laptop server in the field for the image-compression analysis. We tested the system in a field site displaying a heterogeneous suite of sandstones, limestones, mudstones and coal beds. Some of the rocks are partly covered with lichen. The image-matching procedure of this system performed very well with data obtained through our field test, grouping all images of yellow lichens together and grouping all images of a coal bed together, and giving 91% accuracy for similarity detection. Such similarity detection could be employed to make maps of different geological units. The novelty-detection performance of our system was also rather good (64% accuracy). Such novelty detection may become valuable in searching for new geological units, which could be of astrobiological interest. The current system is not directly intended for mapping and novelty detection of a second field site based on image-compression analysis of an image database from a first field site, although our current system could be further developed towards this end. Furthermore, the image-comparison technique is an unsupervised technique that is not capable of directly classifying an image as containing a particular geological feature; labelling of such geological features is donepost factoby human geologists associated with this study, for the purpose of analysing the system's performance. By providing more advanced capabilities for similarity detection and novelty detection, this image-compression technique could be useful in giving more scientific autonomy to robotic planetary rovers, and in assisting human astronauts in their geological exploration and assessment.

China's Jade Rabbit Moon Rover Sends Back First Photos

The first robot rover to land on the Moon in nearly 40 years, China's Jade Rabbit, has begun sending back photos, with shots of its lunar lander. Jade Rabbit rolled down a ramp lowered by the lander and on to the volcanic plain known as Sinus Iridum at 04:35 Beijing time on Saturday (20:35 GMT). It moved to a spot a few metres away, its historic short journey recorded by the lander. On Sunday evening the two machines began photographing each other. A Chinese flag is clearly visible on the Jade Rabbit as it stands deployed on the Moon's surface.

G-2-2 下肢運動想起中の脳波に基づく車両型ロボットの移動方向制御

G-2-2 下肢運動想起中の脳波に基づく車両型ロボットの移動方向制御

A Four-Wheel-Rhombus-Arranged Mobility System for a New Lunar Robotic Rover

Different from traditional ground vehicles, planetary robotic rovers with limited weight and power need to travel in unfamiliar and extremely arduous environments. In this paper, a newly developed four-wheel-rhombus-arranged (FWRA) mobility system is presented as a lunar robotic rover with high mobility and a low-weight structure. The mobility system integrates independent active suspensions with a passive rotary link structure. The active suspension with swing arms improves the rover's capacity to escape from a trapped environment whereas the passive rotary link structure guarantees continuous contact between the four wheels and the terrain. The four-wheel-three-axis rhombus configuration of the mobility system gives a high degree of lightweight structure because it has a simple mechanism with the minimum number of wheels among wheeled rovers with three-axis off-road mobility. The performance evaluation of the lightweight nature of the structure, manoeuvrability and the mobility required in a planetary exploring environment are illustrated by theoretical analysis and partly shown by experiments on the developed rover prototype.

Design and Field Test of a Rover Robot for Antarctic Based on Renewable Energy

Design a rover robot for scientific mission in Antarctic based on renewable energy. Analysis and design the robot's mechanical structure, motion drive, control power system based on specific terrain, surface condition, temperature, wind speed in Antarctic. Wind energy is chosen by more balanced distribution of timeline, vertical axis wind turbine that is fit the structure requirement of the rover. Wheel drive mode and in-hub motor are chosen for higher power efficiency. Design the variable differential linkage for higher trafficability stationarity. The rover does the field test in Zhongshan Station in Antarctic, the results shows that the rover can move on different ground surface condition near Zhongshan Station, the trafficability for obstacle meets requirements, the renewable energy system can provide continuous power supply for the rover. But the results also show that the steering mode, energy capture efficiency, control mode are not meet the requirements of the environment, further research and test is needed.

Five hundred small details

To build a successful product, whether its a suit, a movie, or a robot rover crawling around Mars, requires getting lots of the smallest details correct.

Curiosity's 1-ton touchdown

On 6 August, NASA's robotic rover Curiosity is scheduled to reach the end of its eight-month journey to Mars and begin its highstakes descent down to the surface of the Red Planet.

Raman spectroscopy and the search for life signatures in the ExoMars Mission

AbstractThe survival strategies of extremophilic organisms in terrestrially stressed locations and habitats are critically dependent on the production of protective chemicals in response to desiccation, low wavelength radiation insolation, temperature and the availability of nutrients. The adaptation of life to these harsh prevailing conditions involves the control of the substratal geology; the interaction between the rock and the organisms is critical and the biological modification of the geological matrix plays a very significant role in the overall survival strategy. Identification of these biological and biogeological chemical molecular signatures in the geological record is necessary for the recognition of the presence of extinct or extant life in terrestrial and extraterrestrial scenarios. Raman spectroscopic techniques have been identified as valuable instrumentation for the detection of life extra-terrestrially because of the use of non-invasive laser-based excitation of organic and inorganic molecules, and molecular ions with high discrimination characteristics; the interactions effected between biological organisms and their environments are detectable through the molecular entities produced at the interfaces, for which the vibrational spectroscopic band signatures are unique. A very important attribute of Raman spectroscopy is the acquisition of molecular experimental data non-destructively without the need for chemical or mechanical pre-treatment of the specimen; this has been a major factor in the proposal for the adoption of Raman instrumentation on robotic landers and rovers for planetary exploration, particularly for the forthcoming European Space Agency (ESA)/National Aeronautics and Space Administration (NASA) ExoMars mission. In this paper, the merits of using Raman spectroscopy for the recognition of key molecular biosignatures from several terrestrial extremophile specimens will be illustrated. The data and specimens used in this presentation have been acquired from Arctic and Antarctic cold deserts and a meteorite crater, from which it will be possible to assess spectral data relevant for the detection of extra-terrestrial extremophilic life signatures.

Lunar surface exploration using mobile robots

Abstract A lunar exploration architecture study is being carried out by space agencies. JAXA is carrying out research and development of a mobile robot (rover) to be deployed on the lunar surface for exploration and outpost construction. The main target areas for outpost construction and lunar exploration are mountainous zones. The moon’s surface is covered by regolith. Achieving a steady traversal of such irregular terrain constitutes the major technical problem for rovers. A newly developed lightweight crawler mechanism can effectively traverse such irregular terrain because of its low contact force with the ground. This fact was determined on the basis of the mass and expected payload of the rover. This paper describes a plan for Japanese lunar surface exploration using mobile robots, and presents the results of testing and analysis needed in their development. This paper also gives an overview of the lunar exploration robot to be deployed in the SELENE follow-on mission, and the composition of its mobility, navigation, and control systems.

Chasing the cash [Lunar space mission

The paper discusses the United States plan to return to the moon. It focuses on the government's financial issues and the efforts of private enterprise to fulfill the mission. The paper also discusses the collaboration of NASA with Astrobotics Teechnologies and Carnegie Mellon University in sending a robotic planetary rover, the Red Rover on the moon.

A New Paradigm for Robotic Rovers

We are in the process of developing rovers with extreme mobility needed to explore remote, rugged terrain. We call these systems Tetrahedral Explorer Technologies (TETs). Architecture is based on conformable tetrahedra, the simplest space–filling form, as building blocks, single or networked, where apices act as nodes from which struts reversibly deploy. The tetrahedral framework acts as a simple skeletal muscular structure. We have already prototyped a simple robotic walker from a single reconfigurable tetrahedron capable of tumbling and a more evolved 12Tetrahedral Walker, the Autonomous Landed Investigator (ALI), which has interior nodes for payload, more continuous motion, and is commandable through a user friendly interface. ALI is an EMS level mission concept which would allow autonomous in situ exploration of the lunar poles within the next decade. ALI would consist of one or more 12tetrahedral walkers capable of rapid locomotion with the many degrees of freedom and equipped for navigation in the unilluminated, inaccessible and thus largely unexplored rugged terrains where lunar resources are likely to be found: the Polar Regions. ALI walkers would act as roving reconnaissance teams for unexplored regions, analyzing samples along the way.

Analysis of Solar-Heated Thermal Wadis to SupportExtended-Duration Lunar Exploration

The realization of the renewed exploration of the moon presents many technical challenges; among them is the survival of lunar-surface assets during periods of darkness when the lunar environment is very cold. Thermal wadis are engineered sources of stored solar energy using modified lunar regolith as a thermal storage mass that can supply energy to protect lightweight robotic rovers or other assets during the lunar night. This paper describes an analysis of the performance of thermal wadis based on the known solar illumination of the moon and estimates of producible thermal properties of modified lunar regolith. Analysis has been performed for the lunar equatorial region and for a potential outpost location near the lunar south pole. The calculations indicate that thermal wadis can provide the desired thermal energy and temperature control for the survival of rovers or other equipment during periods of darkness.

Lunar architecture and technology analysis driven by lunar science scenarios

AbstractNASA's Vision for Space Exploration and the missions it comprises pose large‐scale systems‐engineering problems with concomitant large‐budget investment decisions involving multiple disciplines (e.g., science, engineering, information technology), multiple constraints (e.g., time, mass, energy consumption), myriad uncertainties, and a hierarchical structure of problem decomposition with resolution of increasing fidelity. Navigation through this sea of complexity is greatly facilitated by an analytical system that includes optimization and analysis software tools. The interplay between program planning and decision‐support tools is seen here in a case study of a hypothetical mission on the Moon. The architecture of one such tool, HURON, is discussed and its application is illustrated in a comparison of the relative productivity of employing two pressurized or two unpressurized robotic rovers with two pairs of astronauts to conduct a specified group of activities. For the mission scenarios studied, a pair of pressurized rovers is shown to be significantly more productive than a pair of unpressurized rovers when calculating work accomplished divided by marginal operational costs. The HURON decision‐support system presented and successfully applied in this paper deals explicitly with combinatorial explosion of a huge design space in scheduling the activities of agents subject to constraints, deploys a productivity function as a measure of value, and automatically determines a ranked sensitivity list of important inputs. The approach is applicable to a wide class of large‐scale systems‐engineering applications. © 2009 Wiley Periodicals, Inc. Syst Eng

Preliminary assessment of a small robotic rover for Titan exploration

Titan is a very interesting target in deep space exploration. With its solid surface on which a rover can easily travel and its methane lakes which can be sailed it is the ideal target for a deep space mission which includes a mobile platform. In the present paper the general layout of a rover for a mission to Titan is studied, dealing with the mobility, power generation and trajectory control issues. A four-wheels configuration with slip steering was chosen; to compare this solution with the more conventional strategy based on steering wheels, simulations were performed on some trajectories computed through the well known ‘potential’ method, using both slip steering and conventional steering control, for different vehicle speeds. The comparison between the simulated trajectories allows to state the adequateness of the proposed approach. The results here obtained apply not only to a future mission to Titan, but also to other missions designed for the exploration of the satellites of the outer planets having a size comparable with that of Titan and the largest Kuiper belt objects like Pluto and 136472 Makemake.

Axel

Recent scientific findings suggest that some of the most interesting sites for future exploration of planetary surfaces lie in terrains that are currently inaccessible to conventional robotic rovers. To provide robust and flexible access to these terrains, we have been developing Axel, the robotic rover. Axel is a lightweight two-wheeled vehicle that can access steep terrains and negotiate relatively large obstacles because of its actively managed tether and novel wheel design. This article reviews the Axel system and focuses on those system components that affect Axel's steep terrain mobility. Experimental demonstrations of Axel on sloped and rocky terrains are presented.

A variant to Naismith's problem with application to path planning

Naismith obtained a set of empirical rules for the time required to move through a terrain. In this paper we solve the problem of minimization the transit time between two points on a given terrain. We give an interpretation of Naismith's rule which leads to a very elegant geometric construction of the optimal solution. Indeed, there is some ambiguity in the interpretation of Naismith's rule. We first solve the problem for a conical mountain, then generalize for a terrain with arbitrary topography. We conclude with a discussion of the relative merit of our variant with respect to the known solution. In particular, we show that the difference of these interpretations amounts to less than 10% in the worst case, thus justifying the use of this simple solution. This problem is a paradigm for navigation of autonomous vehicles in heterogenous terrain. It may prove useful for path planning for robotic rovers as used for instance on the surface of Mars.

... And Heads to the Moon

The first spacecraft launched beyond Earth orbit by a developing nation is on its way to the moon. Chang'e 1, named for the Chinese goddess who flew to the moon, will arrive in lunar orbit 5 November. The 24 October launch drew large crowds near the Sichuan launch center, was broadcast live on national television, and prompted senior Chinese officials to declare plans to share culled science data. The 2300-kg satellite will circle the moon for a year and send back three-dimensional images of the lunar surface and an analysis of moon dust. India and the United States plan to launch moon orbiters next year, and Japan announced this week that it will launch a robotic rover in the next decade.

Robotic ecological mapping: Habitats and the search for life in the Atacama Desert

As part of the three‐year ‘Life in the Atacama’ (LITA) project, plant and microbial abundance were mapped within three sites in the Atacama Desert, Chile, using an automated robotic rover. On‐board fluorescence imaging of six biological signatures (e.g., chlorophyll, DNA, proteins) was used to assess abundance, based on a percent positive sample rating system and standardized robotic ecological transects. The percent positive rating system scored each sample based on the measured signal strength (0 for no signal to 2 for strong signal) for each biological signature relative to the total rating possible. The 2005 field experiment results show that percent positive ratings varied significantly across Site D (coastal site with fog), with patchy zones of high abundance correlated with orbital and microscale habitat types (heaved surface crust and gravel bars); alluvial fan habitats generally had lower abundance. Non‐random multi‐scale biological patchiness also characterized interior desert Sites E and F, with relatively high abundance associated with (paleo)aqueous habitats such as playas. Localized variables, including topography, played an important, albeit complex, role in microbial spatial distribution. Site D biosignature trends correlated with culturable soil bacteria, with MPN ranging from 10‐1000 CFU/g‐soil, and chlorophyll ratings accurately mapped lichen/moss abundance (Site D) and higher plant (Site F) distributions. Climate also affected biological patchiness, with significant correlation shown between abundance and (rover) air relative humidity, while lichen patterns were linked to the presence of fog. Rover biological mapping results across sites parallel longitudinal W‐E wet/dry/wet Atacama climate trends. Overall, the study highlights the success of targeting of aqueous‐associated habitats identifiable from orbital geology and mineralogy. The LITA experience also suggests the terrestrial study of life and its distribution, particularly the fields of landscape ecology and ecohydrology, hold critical lessons for the search for life on other planets. Their applications to robotic sampling strategies on Mars should be further exploited.