Downwash-Aware Trajectory Planning for Large Quadrotor Teams

We describe a method for formation-change trajectory planning for large quadrotor teams in obstacle-rich environments. Our method decomposes the planning problem into two stages: a discrete planner operating on a graph representation of the workspace, and a continuous refinement that converts the non-smooth graph plan into a set of C^k-continuous trajectories, locally optimizing an integral-squared-derivative cost. We account for the downwash effect, allowing safe flight in dense formations. We demonstrate the computational efficiency in simulation with up to 200 robots and the physical plausibility with an experiment with 32 nano-quadrotors. Our approach can compute safe and smooth trajectories for hundreds of quadrotors in dense environments with obstacles in a few minutes.Comment: 8 page

Master\u27s Project - Wildlife Habitat Linkages Surrounding the Lake George and Southern Lake Champlain Region

Conservation priorities – when developed systematically and objectively – can maximize land protection efforts in heterogeneous landscapes susceptible to parcelization and development. One such region surrounds Lake George and Southern Lake Champlain, nested between the Green and Adirondack Mountains. This mosaic of conserved and private parcels sits upon an array of forest, agriculture, wetland, and development valuable to both humans and resident wildlife species. This landscape’s inherent connectedness provides many benefits to wildlife, including species richness, enhanced persistence, and increased genetic interchange. However, it is difficult to make definitive statements about potential wildlife movement through such complex matrices. Therefore, wildlife modeling approaches have evolved to paint a clearer picture of landscape connectivity. Sam Talbot, ecological planning graduate student at the University of Vermont, worked with the Lake Champlain Land Trust and Lake George Land Conservancy to incorporate landscape connectivity and wildlife corridors into their strategic conservation planning efforts. This project, including a least-cost corridor analysis of the region to highlight large swaths of contiguous habitat, provides the information critical to such conservation efforts. Using the ArcGIS program CorridorDesigner to conduct the analysis, with custom model parameters, identifies three discrete latitudinal corridors between large established wildland blocks. These outputs were then evaluated and compared based on several landscape factors. Ultimately, this study will inform conservation and management decisions, as well as enhance dialogue among local conservation organizations

The performance of space – exploring social and spatial phenomena of interaction patterns in an organisation.

It is often proposed that the design of the physical workplace influences social interaction and therefore organisational behaviour in one way or the other. Yet there is little accordance among scholars on how exactly the relationship between the social space and the social structure of an organisation is constituted. In order to explore this relationship, we combine an interpretive, phenomenological approach with a correlational, syntactic approach. Using the example of a workplace environment studied on multiple layers as well as in detail we propose that physical space influences the formation of social structure and organisational behaviour in manifold, but analytically tractable ways. The application of qualitative and quantitative methods in tandem proves fruitful for understanding the complex phenomena that characterise the emergence of organisational culture

Newmarket Open Space Conservation Plan

Open spaces – forests, fields, wetlands, floodplains, salt marshes, rivers and streams – are integral to our community. These lands and waters that thread through our neighborhoods are a scenic reminder of our history, when people made their living by working the land. Yet we still depend on these open spaces for our health and our wellbeing. These places provide many “services” such as clean air, flood control, filtering pollutants and purifying drinking water, natural pest control, plant pollination, cooler summer temperatures, and areas for relaxing, exercising and recreating. Collectively these can be thought of as a “natural services network” – a minimum framework or backbone of open spaces that offer these services to all of us regardless of age, income, or points of view. New Hampshire is transforming from a largely rural state to a mostly urban and suburban one. This trend will continue at a rapid pace as the State is expected to grow by 358,000 people (or more than 28%) from 2000 to 2025. Most of this growth will occur in the four southeastern counties, with the Town of Newmarket in the heart of this growth area. The major land use trends include loss of unfragmented forestland, lack of protected lands around public water supplies and aquifers, and loss of intact wetlands and wildlife habitat (SPNHF 2005). Many communities, including the residents of Newmarket, have acknowledged these changes and the need to conserve special places and ecosystems by supporting land use planning tools, natural resource inventories, conservation funds, and stewardship of lands. Since 2001, 83 New Hampshire towns have passed open space bond issues or appropriated funds for land acquisition worth more than $135 million (NH Center for Land Conservation Assistance). In 2002, Newmarket residents overwhelmingly passed a$2 million land acquisition bond. Landowners in our community have generously donated interest in land or easements to ensure that conservation values are protected in perpetuity. This support for land and water conservation that benefits all of us is a tribute to the community land ethic in our region. The Town of Newmarket boasts a rich diversity of natural habitats and associated plants and animals. The Lamprey and Piscassic Rivers, Great Bay Estuary, and Tuttle Swamp, to name just a few, all contribute to the sense of place and allure of the town (Map 1). Balancing the preservation of open space with responsible development, long maintained as a priority by Newmarket citizens, business owners and town officials, is necessary, as growth and all its requisite accompaniments present increasing challenges. Recent concerns about the availability of drinking water for Newmarket residents and businesses as well as the floods of 2006 reflect these challenges. As Newmarket continues to grow, so will concern over loss of natural areas, recreational opportunities, and the quality of life that residents have long enjoyed. Maintaining a network of rivers and wetlands, forests and fields throughout Newmarket for the health of the land and people requires vision, support, and action. In 1991, the Town of Newmarket hired the Smart Associates to prepare a Natural Resource Inventory and Conservation Plan. This was the beginning of efforts by the Conservation Commission to conserve important lands identified in the “Smart Report.” In the fifteen years that have elapsed since the Smart Report, Newmarket has undergone many changes, highlighting the need to revisit the current state of natural resources within the community. The Open Space Commission and Conservation Commission have led recent efforts to identify and protect conservation and recreation areas. The Planning Board and staff have led in creating effective land use planning tools that conserve open spaces while allowing orderly and thoughtful development. Together, Newmarket Open Space Conservation Plan Page 7 of 94 these boards applied for a grant from the NH Estuaries Project (NHEP) Technical Assistance Program in 2006 to develop an Open Space Plan. The NHEP awarded the grant of $6,200 to Ibis Wildlife Consulting to work with the Town of Newmarket to prepare this Plan

The Role of Landscape Connectivity in Planning and Implementing Conservation and Restoration Priorities. Issues in Ecology

Landscape connectivity, the extent to which a landscape facilitates the movements of organisms and their genes, faces critical threats from both fragmentation and habitat loss. Many conservation efforts focus on protecting and enhancing connectivity to offset the impacts of habitat loss and fragmentation on biodiversity conservation, and to increase the resilience of reserve networks to potential threats associated with climate change. Loss of connectivity can reduce the size and quality of available habitat, impede and disrupt movement (including dispersal) to new habitats, and affect seasonal migration patterns. These changes can lead, in turn, to detrimental effects for populations and species, including decreased carrying capacity, population declines, loss of genetic variation, and ultimately species extinction. Measuring and mapping connectivity is facilitated by a growing number of quantitative approaches that can integrate large amounts of information about organisms’ life histories, habitat quality, and other features essential to evaluating connectivity for a given population or species. However, identifying effective approaches for maintaining and restoring connectivity poses several challenges, and our understanding of how connectivity should be designed to mitigate the impacts of climate change is, as yet, in its infancy. Scientists and managers must confront and overcome several challenges inherent in evaluating and planning for connectivity, including: •characterizing the biology of focal species; •understanding the strengths and the limitations of the models used to evaluate connectivity; •considering spatial and temporal extent in connectivity planning; •using caution in extrapolating results outside of observed conditions; •considering non-linear relationships that can complicate assumed or expected ecological responses; •accounting and planning for anthropogenic change in the landscape; •using well-defined goals and objectives to drive the selection of methods used for evaluating and planning for connectivity; •and communicating to the general public in clear and meaningful language the importance of connectivity to improve awareness and strengthen policies for ensuring conservation. Several aspects of connectivity science deserve additional attention in order to improve the effectiveness of design and implementation. Research on species persistence, behavioral ecology, and community structure is needed to reduce the uncertainty associated with connectivity models. Evaluating and testing connectivity responses to climate change will be critical to achieving conservation goals in the face of the rapid changes that will confront many communities and ecosystems. All of these potential areas of advancement will fall short of conservation goals if we do not effectively incorporate human activities into connectivity planning. While this Issue identifies substantial uncertainties in mapping connectivity and evaluating resilience to climate change, it is also clear that integrating human and natural landscape conservation planning to enhance habitat connectivity is essential for biodiversity conservation

Indoor Semantic Modelling for Routing: The Two-Level Routing Approach for Indoor Navigation

Humans perform many activities indoors and they show a growing need for indoor navigation, especially in unfamiliar buildings such as airports, museums and hospitals. Complexity of such buildings poses many challenges for building managers and visitors. Indoor navigation services play an important role in supporting these indoor activities. Indoor navigation covers extensive topics such as: 1) indoor positioning and localization; 2) indoor space representation for navigation model generation; 3) indoor routing computation; 4) human wayfinding behaviours; and 5) indoor guidance (e.g., textual directories). So far, a large number of studies of pedestrian indoor navigation have presented diverse navigation models and routing algorithms/methods. However, the major challenge is rarely referred to: how to represent the complex indoor environment for pedestrians and conduct routing according to the different roles and sizes of users. Such complex buildings contain irregular shapes, large open spaces, complicated obstacles and different types of passages. A navigation model can be very complicated if the indoors are accurately represented. Although most research demonstrates feasible indoor navigation models and related routing methods in regular buildings, the focus is still on a general navigation model for pedestrians who are simplified as circles. In fact, pedestrians represent different sizes, motion abilities and preferences (e.g., described in user profiles), which should be reflected in navigation models and be considered for indoor routing (e.g., relevant Spaces of Interest and Points of Interest). In order to address this challenge, this thesis proposes an innovative indoor modelling and routing approach – two-level routing. It specially targets the case of routing in complex buildings for distinct users. The conceptual (first) level uses general free indoor spaces: this is represented by the logical network whose nodes represent the spaces and edges stand for their connectivity; the detailed (second) level focuses on transition spaces such as openings and Spaces of Interest (SOI), and geometric networks are generated regarding these spaces. Nodes of a geometric network refers to locations of doors, windows and subspaces (SOIs) inside of the larger spaces; and the edges represent detailed paths among these geometric nodes. A combination of the two levels can represent complex buildings in specified spaces, which avoids maintaining a largescale complete network. User preferences on ordered SOIs are considered in routing on the logical network, and preferences on ordered Points of Interest (POI) are adopted in routing on geometric networks. In a geometric network, accessible obstacle-avoiding paths can be computed for users with different sizes. To facilitate automatic generation of the two types of network in any building, a new data model named Indoor Navigation Space Model (INSM) is proposed to store connectivity, semantics and geometry of indoor spaces for buildings. Abundant semantics of building components are designed in INSM based on navigational functionalities, such as VerticalUnit(VU) and HorizontalConnector(HC) as vertical and horizontal passages for pedestrians. The INSM supports different subdivision ways of a building in which indoor spaces can be assigned proper semantics. A logical and geometric network can be automatically derived from INSM, and they can be used individually or together for indoor routing. Thus, different routing options are designed. Paths can be provided by using either the logical network when some users are satisfied with a rough description of the path (e.g., the name of spaces), or a geometric path is automatically computed for a user who needs only a detailed path which shows how obstacles can be avoided. The two-level routing approach integrates both logical and geometric networks to obtain paths, when a user provides her/his preferences on SOIs and POIs. For example, routing results for the logical network can exclude unrelated spaces and then derive geometric paths more efficiently. In this thesis, two options are proposed for routing just on the logical network, three options are proposed for routing just on the geometric networks, and seven options for two-level routing. On the logical network, six routing criteria are proposed and three human wayfinding strategies are adopted to simulate human indoor behaviours. According to a specific criterion, space semantics of logical nodes is utilized to assign different weights to logical nodes and edges. Therefore, routing on the logical network can be accomplished by applying the Dijkstra algorithm. If multiple criteria are adopted, an order of criteria is applied for routing according to a specific user. In this way, logical paths can be computed as a sequence of indoor spaces with clear semantics. On geometric networks, this thesis proposes a new routing method to provide detailed paths avoiding indoor obstacles with respect to pedestrian sizes. This method allows geometric networks to be derived for individual users with different sizes for any specified spaces. To demonstrate the use of the two types of network, this thesis tests routing on one level (the logical or the geometric network). Four case studies about the logical network are presented in both simple and complex buildings. In the simple building, no multiple paths lie between spaces A and B, but in the complex buildings, multiple logical paths exist and the candidate paths can be reduced by applying these routing criteria in an order for a user. The relationships of these criteria to user profiles are assumed in this thesis. The proposed geometric routing regarding user sizes is tested with three case studies: 1) routing for pedestrians with two distinct sizes in one space; 2) routing for pedestrians with changed sizes in one space; and 3) a larger geometric network formed by the ones in a given sequence of spaces. The first case shows that a small increase of user size can largely change the accessible path; the second case shows different path segments for distinct sizes can be combined into one geometric path; the third case demonstrates a geometric network can be created ’on the fly’ for any specified spaces of a building. Therefore, the generation and routing of geometric networks are very flexible and fit to given users. To demonstrate the proposed two-level routing approach, this thesis designs five cases. The five cases are distinguished according to the method of model creation (pre-computed or ’on-the-fly’) and model storage (on the client or server). Two of them are realized in this thesis: 1) Case 1 just in the client pre-computes the logical network and derives geometric networks ’on the fly’; 2) Case 2 just in the client pre-computes and stores the logical and geometric networks for certain user sizes. Case 1 is implemented in a desktop application for building managers, and Case 2 is realized as a mobile mock-up for mobile users without an internet connection. As this thesis shows, two-level routing is powerful enough to effectively provide indicative logical paths and/or comprehensive geometric paths, according to different user requirements on path details. In the desktop application, three of the proposed routing options for two-level routing are tested for the simple OTB building and the complex Schiphol Airport building. These use cases demonstrate that the two-level routing approach includes the following merits: It supports routing in different abstraction forms of a building. The INSM model can describe different subdivision results of a building, and it allows two types of routing network to be derived – pure logical and geometric ones. The logical network contains the topology and semantics of indoor spaces, and the geometric network provides accurate geometry for paths. A consistent navigation model is formed with the two networks, i.e., the conceptual and detailed levels. On the conceptual level, it supports routing on a logical network and assists the derivation of a conceptual path (i.e., logical path) for a user in terms of space sequence. Routing criteria are designed based on the INSM semantics of spaces, which can generate logical paths similar to human wayfinding results such as minimizing VerticalUnit or HorizontalConnector. On the detailed level, it considers the size of users and results in obstacle-avoiding paths. By using this approach, geometric networks can be generated to avoid obstacles for the given users and accessible paths are flexibly provided for user demands. This approach can process changes of user size more efficiently, in contrast to routing on a complete geometric network. It supports routing on both the logical and the geometric networks, which can generate geometric paths based on user-specific logical paths, or re-compute logical paths when geometric paths are inaccessible. This computation method is very useful for complex buildings. The two-level routing approach can flexibly provide logical and geometric paths according to user preferences and sizes, and can adjust the generated paths in limited time. Based on the two-level routing approach, this thesis also provides a vision on possible cooperation with other methods. A potential direction is to design more routing options according to other indoor scenarios and user preferences. Extensions of the two-level routing approach, such as other types of semantics, multi-level networks and dynamic obstacles, will make it possible to deal with other routing cases. Last but not least, it is also promising to explore its relationships with indoor guidance, different building subdivisions and outdoor navigation. &nbsp