Hazard Avoidance Research Articles

Improving the probability of success in resource plays

The role of the geophysicist in resource plays has been hard to define. There is obvious benefit to seismic structural interpretation for hazard avoidance and model building for geosteering applications, but when it comes to predicting optimal well placement, much of the industry still is struggling. Common applications of seismic attributes search for deterministic predictions using attributes such as rock strength and anisotropy. However, even with many claims of success and a rich base of literature, the value and use of these approaches are lacking in practice. A simple case study shows the value added by using a single seismic attribute, curvature, in the Barnett Shale. The key to understanding this value is the use of Bayesian statistics. For this case, controlling for just one seismic attribute is seen to increase the probability of a successful well by 10% or more, also leading to substantial increases in rate of return of 10 percentage points or more.

Robust hazard matching approach for visual navigation application in planetary landing

Visual navigation is favored in future planetary landing mission for its ability of providing the absolute pose of lander with respect to the landing spot. However, such method often brings much computational burden to spacecraft, whose hardware is specially degraded for reliability issue. In addition, unlike natural ground environment, planetary surface is often barren and short of distinctive landmarks, which also poses great challenge to visual navigation. Planetary terrain hazard poses potential threat to planetary landing mission, some large-size hazards like boulders and craters must be targeted before a landing mission and detected in real-time during the landing phase for spacecraft to make necessary avoiding moves. It is expected that an autonomous safe landing and hazard avoidance system will bring much more scientific rewards to us. To cater for the requirements of such system, a robust and fast terrain hazard matching approach designed for visual navigation is proposed in this paper. First, image positions of detected hazards are used to generate affine invariants, after that, affine invariants are exploited to generate representative sets to describe hazard, thirdly, two finite set based hazard matching algorithms that based upon seeking similarity of representative sets are proposed, in which the advantage of set based feature matching technique is highlighted. Validity of our proposed algorithm is demonstrated by the comparison with state-of-the-art feature matching algorithms using real planetary images. Finally, different visual navigation scenarios were simulated by using a landscape generation toolbox, from which the effect of hazard detection on proposed hazard matching algorithm is further examined.

月球软着陆自主障碍识别与避障制导方法

An autonomous hazard detection and roughne hazard-avoidance guidance method for soft lunar landing is presented to mitigate the landing risks due to the uncertainty and hazards of the lunar terrain, such as surface roughness and slope. The method is composed of roughne hazard detection and a landing site selection algorithm. The high-precision relative autonomous navigation algorithm is based on image data, and the autonomous hazard-avoidance guidance algorithm is based on an adjusted thrust engine. The theoretic deduction and simulation analysis shows that a safe landing site is acquired and autonomous pinpoint hazard avoidance is achieved using the presented method. The method can be used to improve the achievement of a soft landing and has been successfully used in the Change-3 soft landing mission.

Inuit Traditional Ecological Knowledge (TEK) Subsistence Hunting and Adaptation to Climate Change in the Canadian Arctic

This paper examines the role of Inuit traditional ecological knowledge (TEK) in adaptation to climate change in the Canadian Arctic. It focuses on Inuit relationships with the Arctic environment, including hunting knowledge and land skills, and examines their roles in adaptation to biophysical changes that affect subsistence hunting. In several instances, TEK underpins competency in subsistence and adaptations to changing conditions, which includes flexibility with regard to seasonal cycles of hunting and resource use, hazard avoidance through detailed knowledge of the environment and understanding of ecosystem processes, and emergency preparedness, e.g., knowing what supplies to take when traveling and how to respond in emergency situations. Despite the documented importance of TEK in adaptation and in maintaining a level of competency in subsistence, the relationships between TEK and adaptation to climate change are not well defined in the scholarly literature. This paper aims to conceptualize the relationships between TEK and adaptation to climate change by drawing on case study research with Inuit in the Canadian Arctic. TEK is considered an element of adaptive capacity (or resilience) that is expressed as adaptation if TEK is drawn upon to adapt to changing conditions. This capacity depends on the development, accumulation, and transmission of TEK within and among generations.

CubeSail Displaced Orbit Design for Near Earth Object Observation

Microsatellites known as “CubeSats” have recently been developed to enable comparatively inexpensive and timely access to space for small payloads. As a new standard for small satellites, the CubeSat has shown great promise for space applications such as earth observation, planetary science and space physics mission. In this paper a “CubeSail” mission – a CubeSat deployed with a solar sail –for near earth object (NEO) observation is introduced. It is important to observe a NEO which may intersect or pass close to earth space before instigating any procedure for hazard avoidance. Furthermore, close observation of NEO may also be important for exploiting the new resources and exploring new living environment in outer space. This paper describes the concept of a large numbers of CubeSails deployed in the vicinity of the NEO for observation purposes. The dynamic model of the NEO-centreddis placed orbit in space is analysed. The solar radiation pressure on the sail can be utilised as propulsion to compensate for third body gravitational perturbation. To maintain the relative motion/position between a CubeSail and the NEO, periodic initial conditions are searched, which also must satisfy some observation mission constraints. A simulation study is carried out using the near earth asteroid Apophis 99942, discovered in recent years.

The Optimization of Satellite Landing Site based on Particle Swarm Optimization

Hazard avoidance is one of the key stages in the satellite's soft landing process, during which the selection of the landing site would have a huge influence on the satellite safe landing. In this paper, a new design method is presented for determining the landing site selection using Particle Swarm Optimization based on the Moon’s grounds image taken by moon satellite. Applying this method, the problem of hazard avoidance can be converted into the optimization of the value of “obstacle function” after processing the image employing the median filter algorithm. In order to discuss and to compare the efficiency of the different optimization methods, three algorithms including Particle Swarm Optimization, Genetic Algorithm and Global Search Algorithm are tested to solve this problem. The results show that Particle Swarm Optimization has the more satisfactory optimization results and the quickest optimization speed in the landing site selection. The detailed comparisons are introduced in the body paragraph.

Reducing risk from lahar hazards: concepts, case studies, and roles for scientists

Lahars are rapid flows of mud–rock slurries that can occur without warning and catastrophically impact areas more than 100 km downstream of source volcanoes. Strategies to mitigate the potential for damage or loss from lahars fall into four basic categories: (1) avoidance of lahar hazards through land-use planning; (2) modification of lahar hazards through engineered protection structures; (3) lahar warning systems to enable evacuations; and (4) effective response to and recovery from lahars when they do occur. Successful application of any of these strategies requires an accurate understanding and assessment of the hazard, an understanding of the applicability and limitations of the strategy, and thorough planning. The human and institutional components leading to successful application can be even more important: engagement of all stakeholders in hazard education and risk-reduction planning; good communication of hazard and risk information among scientists, emergency managers, elected officials, and the at-risk public during crisis and non-crisis periods; sustained response training; and adequate funding for risk-reduction efforts. This paper reviews a number of methods for lahar-hazard risk reduction, examines the limitations and tradeoffs, and provides real-world examples of their application in the U.S. Pacific Northwest and in other volcanic regions of the world. An overriding theme is that lahar-hazard risk reduction cannot be effectively accomplished without the active, impartial involvement of volcano scientists, who are willing to assume educational, interpretive, and advisory roles to work in partnership with elected officials, emergency managers, and vulnerable communities.

Modeling cratered surfaces with real and synthetic terrain for testing planetary landers

The autonomous guidance of a spacecraft lander requires extensive testing to develop and prove the technology. Methods such as machine vision for navigation and both vision and LIDAR for hazard avoidance are being studied and developed to provide precise, robust lander guidance systems. A virtual test environment that can simulate these instruments is a vital tool to aid this work. When available, terrain elevation models can provide a base for simulation but they frequently contain artifacts, gaps, or may not have the required resolution. We propose novel techniques to model heavily cratered surfaces for testing planetary landers by combining crater models and fractal terrain to create a multiresolution mesh for simulating a spacecraft descent and landing. The synthetically enhanced models are evaluated by comparing enhanced terrain based on Clementine/RADAR data with higher resolution terrain models from the Selene and the Lunar Reconnaissance Orbiter (LRO) to show that the artificial models are suitable for testing planetary lander systems.

Autonomous hazard avoidance control for Chang’E-3 soft landing

ChangE-3 is the first mission of Chinese soft landing on celestial body outside Earth. ChangE-3 firstly implements the autonomous hazard avoidance of soft landing using the onboard measured image data. For the feature of autonomous hazard avoidance mission, ChangE-3 firstly presents the relay hazard avoidance control method including the large hazard avoidance of gray-scale-safe & attitude maneuver and the fine hazard avoidance of altitude-safe & position-attitude maneuver. The real flight results of ChangE-3 show that in the powered descent process the safe landing site is acquired, the precise hazard avoidance maneuver is achieved perfectly, and the safety of touch point for soft landing is insured. The autonomous hazard avoidance control and onboard flight results for ChangE-3 are described.

A Cross-Site Visual Localization Method for Yutu Rover

Abstract. Localization of the rover is critical to support science and engineering operations in planetary rover missions, such as rover traverse planning and hazard avoidance. It is desirable for planetary rover to have visual localization capability with high degree of automation and quick turnaround time. In this research, we developed a visual localization method for lunar rover, which is capable of deriving accurate localization results from cross-site stereo images. Tie points are searched in correspondent areas predicted by initial localization results and determined by ASIFT matching algorithm. Accurate localization results are derived from bundle adjustment based on an image network constructed by the tie points. In order to investigate the performance of proposed method, theoretical accuracy analysis on is implemented by means of error propagation principles. Field experiments were conducted to verify the effectiveness of the proposed method in practical applications. Experiment results prove that the proposed method provides more accurate localization results (1 %~4 %) than dead-reckoning. After more validations and enhancements, the developed rover localization method has been successfully used in Chang'e-3 mission operations.

Guidance navigation and control for Chang’E-3 powered descent

It is the first time for ChangE-3 lander landing on an extraterrestrial celestial body in China. Guidance, navigation and control system is one of the most important systems. Guidance, navigation, hazard avoidance and attitude control are demanded strictly for safe landing during powered descent. Adaptive powered explicit guidance, multibeam fault-tolerant navigation and partition quaternion control are proposed for ChangE-3 mission. The results in orbit show that these techniques are reasonable. The landing mission is successful and the performances of landing precision, attitude and velocity are better than the corresponding requirements. This paper presents requirement, composing and technique of ChangE-3 GNC system and results in orbit.

Effect of age and pop out distracter on attended field of view

PurposeTo investigate the functional field of view (FFOV) of younger and older individuals using the attended field of view (AFOV), a method which allows for eye and head movement. The impact of a pop out distracter and a dual task on the FFOV measure was also investigated. MethodsNine young adult (25±6 years) and 9 older participants (72±4 years) took part in the experiment. The AFOV test involved the binocular detection and localization of a white target (Landolt-C) in a field of 24 white rings (distracters). The further AFOV tests were modified to include the presence of a pop out distracter, a dual task condition, and a combination of the two. ResultsOlder observers had lower viewing efficiency (log [1/presentation time]) in all conditions (pooled mean across conditions: older: 0.05±0.02; younger: 0.48±0.04) than the younger group. The addition of dual or a pop out distracter did not affect the older group (mean difference ∼104±150ms and ∼124±122ms respectively) but the additional pop out distracter reduced the efficiency of the younger group for targets near fixation (mean difference ∼68±35ms). ConclusionBetter viewing efficiency was observed in younger individuals compared to older individuals. Difficulty in disregarding irrelevant stimuli and thereby resorting to inefficient search strategy is proposed as the reason for the differences. The finding that both older and younger individuals are not affected significantly by the presence of the irrelevant pop out distracter has implications in situations such as driving or hazard avoidance. In such scenarios, search performance is likely not impaired beyond what is found with distracters (visual clutter) in the environment.

Stages and Levels of Automation in Support of Space Teleoperations

This study examined the impact of stage of automation on the performance and perceived workload during simulated robotic arm control tasks in routine and off-nominal scenarios. Automation varies with respect to the stage of information processing it supports and its assigned level of automation. Making appropriate choices in terms of stages and levels of automation is critical to ensure robust joint system performance. To date, this issue has been empirically studied in domains such as aviation and medicine but not extensively in the context of space operations. A total of 36 participants played the role of a payload specialist and controlled a simulated robotic arm. Participants performed fly-to tasks with two types of automation (camera recommendation and trajectory control automation) of varying stage. Tasks were performed during routine scenarios and in scenarios in which either the trajectory control automation or a hazard avoidance automation failed. Increasing the stage of automation progressively improved performance and lowered workload when the automation was reliable, but incurred severe performance costs when the system failed. The results from this study support concerns about automation-induced complacency and automation bias when later stages of automation are introduced. The benefits of such automation are offset by the risk of catastrophic outcomes when system failures go unnoticed or become difficult to recover from. A medium stage of automation seems preferable as it provides sufficient support during routine operations and helps avoid potentially catastrophic outcomes in circumstances when the automation fails.

Single camera absolute motion based digital elevation mapping for a next generation planetary lander

Robotic planetary surface exploration missions are becoming much more ambitious in their science goals as they attempt to answer the bigger questions relating to the possibility of life elsewhere in our solar system. Answering these questions will require scientifically rich landing sites. Such sites are unlikely to be located in relatively flat regions that are free from hazards, therefore there is a growing need for next generation entry descent and landing systems to possess highly sophisticated navigation capabilities coupled with active hazard avoidance that can enable a pin-point landing. As a first step towards achieving these goals, a multi-source, multi-rate data fusion algorithm is presented that combines single camera recursive feature-based structure from motion (SfM) estimates with measurements from an inertial measurement unit in order to overcome the scale ambiguity problem by directly estimating the unknown scale factor. This paper focuses on accurate estimation of absolute motion parameters, as well as the estimation of sparse landing site structure to provide a starting point for hazard detection. We assume no prior knowledge of the landing site terrain structure or of the landing craft motion in order to fully assess the capabilities of the proposed algorithm to allow a pin-point landing on distant solar system bodies where accurate knowledge of the desired landing site may be limited. We present results using representative synthetic images of deliberately challenging landing scenarios, which demonstrates that the proposed method has great potential.

The Distinction Between Risk and Hazard: Understanding and Use in Stakeholder Communication

A major issue in all risk communication efforts is the distinction between the terms "risk" and "hazard." The potential to harm a target such as human health or the environment is normally defined as a hazard, whereas risk also encompasses the probability of exposure and the extent of damage. What can be observed again and again in risk communication processes are misunderstandings and communication gaps related to these crucial terms. We asked a sample of 53 experts from public authorities, business and industry, and environmental and consumer organizations in Germany to outline their understanding and use of these terms using both the methods of expert interviews and focus groups. The empirical study made clear that the terms risk and hazard are perceived and used very differently in risk communication depending on the perspective of the stakeholders. Several factors can be identified, such as responsibility for hazard avoidance, economic interest, or a watchdog role. Thus, communication gaps can be reduced to a four-fold problem matrix comprising a semantic, conceptual, strategic, and control problem. The empirical study made clear that risks and hazards are perceived very differently depending on the stakeholders' perspective. Their own worldviews played a major role in their specific use of the two terms hazards and risks in communication.

Safe Maritime Autonomous Navigation With COLREGS, Using Velocity Obstacles

This paper presents an autonomous motion planning algorithm for unmanned surface vehicles (USVs) to navigate safely in dynamic, cluttered environments. The algorithm not only addresses hazard avoidance (HA) for stationary and moving hazards, but also applies the International Regulations for Preventing Collisions at Sea (known as COLREGS, for COLlision REGulationS). The COLREGS rules specify, for example, which vessel is responsible for giving way to the other and to which side of the “stand-on” vessel to maneuver. Three primary COLREGS rules are considered in this paper: crossing, overtaking, and head-on situations. For autonomous USVs to be safely deployed in environments with other traffic boats, it is imperative that the USV's navigation algorithm obeys COLREGS. Furthermore, when other boats disregard their responsibility under COLREGS, the USV must fall back to its HA algorithms to prevent a collision. The proposed approach is based on velocity obstacles (VO) method, which generates a cone-shaped obstacle in the velocity space. Because VOs also specify on which side of the obstacle the vehicle will pass during the avoidance maneuver, COLREGS are encoded in the velocity space in a natural way. Results from several experiments involving up to four vessels are presented, in what we believe is the first on-water demonstration of autonomous COLREGS maneuvers without explicit intervehicle communication. We also show an application of this motion planner to a target trailing task, where a strategic planner commands USV waypoints based on high-level objectives, and the local motion planner ensures hazard avoidance and compliance with COLREGS during a traverse.

Variable Gear Ratio Control Using Vehicle Body Slip Angle

Vehicles with variable steering characteristics have long been studied and compared with those having typical fixed gear ratio steering, and the variable gear ratio properties are reported to have improved maneuverability and stability in high-speed lane changes and on slippery low-friction road surfaces. However, it is not clear how gear ratios should be set for individual vehicle characteristics. Therefore, the present study has investigated a variable steering gear system using body slip angle feedback for the purpose of improved maneuverability and stability in the critical cornering range and upwards, in excess of the critical limit, and into the countersteer range. The results of a driving simulator experiment show that the steering effect improves and maneuverability and stability increase in the critical cornering range and upwards, in excess of the critical limit, and into the countersteer range by applying linear-variable control to the steering ratio from a body slip angle of 5?. This result is seen both in double lane changes, such as in hazard avoidance, and in J-turns with long drifting. Moreover, it shows an improvement in drift controllability through prompt countersteering. Overall, the present system can enhance the driver’s hazard avoidance capability.

Active Control Method for Critical Cornering Range

It has been reported that steering systems with derivative terms have a heightened lateral acceleration and yaw rate response in the normal driving range. However, in ranges where the lateral acceleration is high, the cornering force of the front wheels decreases and hence becomes less effective. Therefore, we applied traction control for the inner and outer wheels based on the steering angle velocity to improve the steering effectiveness at high lateral accelerations. An experiment using a driving simulator showed that the vehicle’s yaw rate response improved for a double lane change to avoid a hazard; this improves hazard avoidance performance. Regarding improved vehicle control in the cornering margins, traction control for the inner and outer wheels is being developed further, and much research and development has been reported. However, in the total skid margin, where few margin remains in the forward and reverse drive forces on the tires, spinout is unavoidable. Therefore, we applied tire camber angle control to improve vehicle maneuverability in the total skid margin. An experiment using a driving simulator has confirmed that the vehicle’s lateral acceleration at the turning limit can be improved by controlling the camber angle. Because of this, camber angle control promises to be more effective than traction control for the inner and outer wheels. By applying this type of steering control, it is possible to increase maneuverability and stability in the cornering margins.

Phytoextraction as a tool for green chemistry

The unique chemical and physical proper- ties of metals mean that they are extensively utilized by industry in a huge variety of applications, including electronics, materials, industrial catalysts and chemi- cals. The increased consumer demand from a growing population worldwide with rising aspirations for a better life has resulted in concerns over the security of supply and accessibility of these valuable elements. As such, there is a growing need to develop alternative meth- ods to recover them from waste repositories, current or historic, both for hazard avoidance and potentially, as a new source of metals for industry. Phytoextrac- tion (the use of plants for the recovery of metals from waste repositories) is a green and novel technique for metal recovery, which, if done with the goal of resource supply rather than hazard mitigation, is termed phy- tomining. The ability for plants to form metallic nan- oparticles as a consequence of phytoextraction could make the recovered metal ideally suited for utilization in green chemical technologies, such as catalysis. This review focuses on a multidisciplinary approach to ele- mental sustainability and highlights important aspects of metal lifecycle analysis, metal waste sources (includ- ing mine tailings), phytoextraction and potential green chemical applications that may result from the integra- tion of these approaches.

Investigation of heavy metals in frequently utilized medicinal plants collected from environmentally diverse locations of north western India

The increasing prevalence of environmental pollution, especially soil contamination with heavy metals has led to their uptake in the human food chains through plant parts. Accumulation and magnification of heavy metals in human tissues through consumption of herbal remedies can cause hazardous impacts on health. Therefore, chemical profiling of nine heavy metals (Mn, Cr, Pb, Fe, Cd, Co, Zn, Ni and Hg) was undertaken in stem and leaf samples of ten medicinal plants (Acacia nilotica, Bacopa monnieri, Commiphora wightii, Ficus religiosa, Glycyrrhiza glabra, Hemidesmus indicus, Salvadora oleoides, Terminalia bellirica, Terminalia chebula and Withania somnifera) collected from environmentally diverse regions of Haryana and Rajasthan states in North-Western India. Concentration of all heavy metals, except Cr, was within permissible limits in the tested stem and leaf samples. Leaf samples had consistently more Cr compared to respective stem samples with highest concentration in leaf samples of Bacopa monnieri (13.19 ± 0.0480 ppm) and stem samples of Withania somnifera (4.93 ± 0.0185 ppm) both collected from Bahadurgarh (heavy industrial area), Haryana. This amount was beyond the permissible limit of 2.0 ppm defined by WHO for raw herbal material. Other two most perilous metals Pb (2.64 ± 0.0260) and Cd (0.04 ± 0.0274) were also recorded in Bahadurgarh region, although below permissible limits. Concentration of Hg remained below detectable levels in all the leaf and stem samples tested. These results suggested that cultivation of medicinal plants and other dietary herbs should be curtailed near environmentally polluted especially industrial areas for avoidance of health hazards.