Robot path planning in dynamic environments using a simulated annealing based approach

Mobile robots are widely used in many industrial fields. Research on path planning for mobile robots is one of the most important aspects in mobile robots research. Path planning for a mobile robot is to find a collision-free route, through the robot’s environment with obstacles, from a specified start location to a desired goal destination while satisfying certain optimization criteria. Most of the existing path planning methods, such as the visibility graph, the cell decomposition, and the potential field are designed with the focus on static environments, in which there are only stationary obstacles. However, in practical systems such as Marine Science Research, Robots in Mining Industry, and RoboCup games, robots usually face dynamic environments, in which both moving and stationary obstacles exist. Because of the complexity of the dynamic environments, research on path planning in the environments with dynamic obstacles is limited. Limited numbers of papers have been published in this area in comparison with hundreds of reports on path planning in stationary environments in the open literature. Recently, a genetic algorithm based approach has been introduced to plan the optimal path for a mobile robot in a dynamic environment with moving obstacles. However, with the increase of the number of the obstacles in the environment, and the changes of the moving speed and direction of the robot and obstacles, the size of the problem to be solved increases sharply. Consequently, the performance of the genetic algorithm based approach deteriorates significantly. This motivates the research of this work. This research develops and implements a simulated annealing algorithm based approach to find the optimal path for a mobile robot in a dynamic environment with moving obstacles. The simulated annealing algorithm is an optimization algorithm similar to the genetic algorithm in principle. However, our investigation and simulations have indicated that the simulated annealing algorithm based approach is simpler and easier to implement. Its performance is also shown to be superior to that of the genetic algorithm based approach in both online and offline processing times as well as in obtaining the optimal solution for path planning of the robot in the dynamic environment. The first step of many path planning methods is to search an initial feasible path for the robot. A commonly used method for searching the initial path is to randomly pick up some vertices of the obstacles in the search space. This is time consuming in both static and dynamic path planning, and has an important impact on the efficiency of the dynamic path planning. This research proposes a heuristic method to search the feasible initial path efficiently. Then, the heuristic method is incorporated into the proposed simulated annealing algorithm based approach for dynamic robot path planning. Simulation experiments have shown that with the incorporation of the heuristic method, the developed simulated annealing algorithm based approach requires much shorter processing time to get the optimal solutions in the dynamic path planning problem. Furthermore, the quality of the solution, as characterized by the length of the planned path, is also improved with the incorporated heuristic method in the simulated annealing based approach for both online and offline path planning.

Developing an integrated decision model for the enhancement of sustainability deliverables for Australian road infrastructure projects

Road and highway infrastructure provides the backbone for a nation's economic growth. The versatile dispersion of population in Australia, from sparsely settled communities in remote areas to regenerated inner city suburbs with high density living in metropolitans, calls for continuing development and improvement on roads infrastructure under the current federal government policies and state governments' strategic plans. As road infrastructure projects involve large resources and mechanism, achieving sustainability not only in economic scales but also through environmental and social responsibility becomes a crucial issue. Current efforts are often impeded by different interpretation on sustainability agenda by stakeholders involved in these types of projects. As a result, sustainability deliverables at the project level is not often as transparent and measurable, compared to promises in project briefs and designs. This paper reviews the past studies on sustainable infrastructure construction, focusing on roads and highway projects. Through literature study and consultation with the industry, key sustainability indicators specific to road infrastructure projects have been identified. Based on these findings, this paper introduces an on-going research project aimed at identifying and integrating the different perceptions and priority needs of the stakeholders, and issues that impact on the gap between sustainability foci and its actual realization at project end level. The exploration helps generate an integrated decision-making model for sustainable road infrastructure projects. The research will promote to the industry more systematic and integrated approaches to decision-making on the implementation of sustainability strategies to achieve deliverable goals throughout the development and delivery process of road infrastructure projects in Australia.

Railways, Urban Development and Town Planning in Britain: 1948–2008, Haywood R. Ashgate (2009). £65.00, ISBN: 9780754673927

This book is a thorough investigation of the relationship between land use planning and the railways in Britain, through review of the factors affecting the two sectors and their integration during the period of public ownership. The rationale behind the book is explained as a timely analysis of the dynamic correlation involving town planning and management of the railway in a period when growing congestion on the road network is forcing people to look for alternative modes and capacity is badly needed to accommodate this increased demand for travel. The book calls for a modal shift from road to rail for passenger and freight traffic.

Beyond airport enclaves : insights for overcoming turf wars

Airports, over time, have emerged as separate independent entities often described as ‘enclaves’. As such airports regularly planned and implemented developments within their boundaries with limited inclusion of local actors in decision making processes. Urban encroachment on airport boundaries has increasingly focused the planning interests of airports to consider what their neighbouring cities are doing. Likewise city planners are progressively more interested in the development activities of airports. Despite shared interests in what happens on the either side of the fence line, relationships between airports and their neighbouring cities have often been strained, if not, at times, hostile. A number of strategies and conceptualisations for the co-existence of urban and airport environs have been put forward. However, these models are likely to have a limited effect unless they can be implemented to maximise opportunities for both cities and airports, and at the same time not confound their long-term interests. The isolation of airport planning from local and regional planning agencies, and the resulting power struggles are not new. Under current conditions the need to ‘bridge the gap’ between airports and their urban surrounds has become an increasing, yet under explored imperative. This paper examines the decision making arena for airport-region development to define the barriers, enablers, tensions and puzzles for the governance of airport-region development, from a cross-country perspective. Findings suggest that while there are many embedded rule structures that foster airport-region tensions, there are nonetheless a number of pathways for moving airports beyond decision making enclaves, to more integrated mechanisms for city and regional planning. In providing preliminary answers for overcoming the barriers, tensions and intractable issues of mutually agreeable airport and city development, the research makes a primary contribution to the ground level governance of collaborative planning. This research also serves as a launching point for future, more detailed research into the areas of airport-region decision making and collaborative planning for airport-regions. This work was carried out through the Airport Metropolis Research Project under the Australian Research Council’s Linkage Projects funding scheme (LP0775225).

Multi-objective mission flight planning in civil unmanned aerial systems

Unmanned Aerial Vehicles (UAVs) are emerging as an ideal platform for a wide range of civil applications such as disaster monitoring, atmospheric observation and outback delivery. However, the operation of UAVs is currently restricted to specially segregated regions of airspace outside of the National Airspace System (NAS). Mission Flight Planning (MFP) is an integral part of UAV operation that addresses some of the requirements (such as safety and the rules of the air) of integrating UAVs in the NAS. Automated MFP is a key enabler for a number of UAV operating scenarios as it aids in increasing the level of onboard autonomy. For example, onboard MFP is required to ensure continued conformance with the NAS integration requirements when there is an outage in the communications link. MFP is a motion planning task concerned with finding a path between a designated start waypoint and goal waypoint. This path is described with a sequence of 4 Dimensional (4D) waypoints (three spatial and one time dimension) or equivalently with a sequence of trajectory segments (or tracks). It is necessary to consider the time dimension as the UAV operates in a dynamic environment. Existing methods for generic motion planning, UAV motion planning and general vehicle motion planning cannot adequately address the requirements of MFP. The flight plan needs to optimise for multiple decision objectives including mission safety objectives, the rules of the air and mission efficiency objectives. Online (in-flight) replanning capability is needed as the UAV operates in a large, dynamic and uncertain outdoor environment. This thesis derives a multi-objective 4D search algorithm entitled Multi- Step A* (MSA*) based on the seminal A* search algorithm. MSA* is proven to find the optimal (least cost) path given a variable successor operator (which enables arbitrary track angle and track velocity resolution). Furthermore, it is shown to be of comparable complexity to multi-objective, vector neighbourhood based A* (Vector A*, an extension of A*). A variable successor operator enables the imposition of a multi-resolution lattice structure on the search space (which results in fewer search nodes). Unlike cell decomposition based methods, soundness is guaranteed with multi-resolution MSA*. MSA* is demonstrated through Monte Carlo simulations to be computationally efficient. It is shown that multi-resolution, lattice based MSA* finds paths of equivalent cost (less than 0.5% difference) to Vector A* (the benchmark) in a third of the computation time (on average). This is the first contribution of the research. The second contribution is the discovery of the additive consistency property for planning with multiple decision objectives. Additive consistency ensures that the planner is not biased (which results in a suboptimal path) by ensuring that the cost of traversing a track using one step equals that of traversing the same track using multiple steps. MSA* mitigates uncertainty through online replanning, Multi-Criteria Decision Making (MCDM) and tolerance. Each trajectory segment is modeled with a cell sequence that completely encloses the trajectory segment. The tolerance, measured as the minimum distance between the track and cell boundaries, is the third major contribution. Even though MSA* is demonstrated for UAV MFP, it is extensible to other 4D vehicle motion planning applications. Finally, the research proposes a self-scheduling replanning architecture for MFP. This architecture replicates the decision strategies of human experts to meet the time constraints of online replanning. Based on a feedback loop, the proposed architecture switches between fast, near-optimal planning and optimal planning to minimise the need for hold manoeuvres. The derived MFP framework is original and shown, through extensive verification and validation, to satisfy the requirements of UAV MFP. As MFP is an enabling factor for operation of UAVs in the NAS, the presented work is both original and significant.

View from a bridge : what makes a musical city

The attention paid by the British music press in 1976 to the release of The Saints first single “I’m Stranded” was the trigger for a commercial and academic interest in the Brisbane music scene which still has significant energy. In 2007, Brisbane was identifed by Billboard Magazine as a “hot spot” of independent music. A place to watch. Someone turned a torch on this town, had a quick look, moved on. But this town has always had music in it. Some of it made by me. So, I’m taking this connection of mine, and working it into a contextual historical analysis of the creative lives of Brisbane musicians. I will be interviewing a number of Brisbane musicians. These interviews have begun, and will continue to be be conducted in 2011/2012. I will ask questions and pursue memories that will encompass family, teenage years, siblings, the suburbs, the city, venues, television and radio; but then widen to welcome the river, the hills and mountains, foes and friends, beliefs and death. The wider research will be a contextual historical analysis of the creative lives of Brisbane musicians. It will explore the changing nature of their work practices over time and will consider the notion, among other factors, of ‘place’ in both their creative practice and their creative output. It will also examine how the presence of the practitioners and their work is seen to contribute to the cultural life of the city and the creative lives of its citizens into the future. This paper offers an analysis of this last notion: how does this city see its music-makers? In addition to the interviews, over 300 Brisbane musicians were surveyed in September 2009 as part of a QUT-initiated recorded music event (BIGJAM). Their responses will inform the production of this paper.

Solar powered UAV for fire prevention and planning

This project aims to develop a methodology for designing and conducting a systems engineering analysis to build and fly continuously, day and night, propelled uniquely by solar energy for one week with a 0.25Kg payload consuming 0.5 watt without fuel or pollution. An airplane able to fly autonomously for many days could find many applications. Including coastal or border surveillance, atmospherical and weather research and prediction, environmental, forestry, agricultural, and oceanic monitoring, imaging for the media and real-estate industries, etc. Additional advantages of solar airplanes are their low cost and the simplicity with which they can be launched. For example, in the case of potential forest fire risks during a warm and dry period, swarms of solar airplanes, easily launched with the hand, could efficiently monitor a large surface, reporting rapidly any fire starts. This would allow a fast intervention and thus reduce the cost of such disaster, in terms of human and material losses. At higher dimension, solar HALE platforms are expected to play a major role as communication relays and could replace advantageously satellites in a near future.

Planning and evaluation

Introduction: The core business of public health is to protect and promote health in the population. Public health planning is the means to maximise these aspirations. Health professionals develop plans to address contemporary health priorities as the evidence about changing patterns of mortality and morbidity is presented. Officials are also alert to international trends in patterns of disease that have the potential to affect the health of Australians. Integrated planning and preparation is currently underway involving all emergency health services, hospitals and population health units to ensure Australia's quick and efficient response to any major infectious disease outbreak, such as avian influenza (bird flu). Public health planning for the preparations for the Sydney Olympics and Paralympic Games in 2000 took almost three years. ‘Its major components included increased surveillance of communicable disease; presentations to sentinel emergency departments; medical encounters at Olympic venues; cruise ship surveillance; environmental and food safety inspections; bioterrorism surveillance and global epidemic intelligence’ (Jorm et al 2003, 102). In other words, the public health plan was developed to ensure food safety, hospital capacity, safe crowd control, protection against infectious diseases, and an integrated emergency and disaster plan. We have national and state plans for vaccinating children against infectious diseases in childhood; plans to promote dental health for children in schools; and screening programs for cervical, breast and prostate cancer. An effective public health response to a change in the distribution of morbidity and mortality requires planning. All levels of government plan for the public’s health. Local governments (councils) ensure healthy local environments to protect the public’s health. They plan parks for recreation, construct traffic-calming devices near schools to prevent childhood accidents, build shade structures and walking paths, and even embed drafts/chess squares in tables for people to sit and play. Environmental Health officers ensure food safety in restaurants and measure water quality. These public health measures attempt to promote the quality of life of residents. Australian and state governments produce plans that protect and promote health through various policy and program initiatives and innovations. To be effective, program plans need to be evaluated. However, building an integrated evaluation plan into a program plan is often forgotten, as planning and evaluation are seen as two distinct entities. Consequently, it is virtually impossible to measure, with any confidence, the extent to which a program has achieved its goals and objectives. This chapter introduces you to the concepts of public health program planning and evaluation. Case studies and reflection questions are presented to illustrate key points. As various authors use different terminology to describe the same concepts/actions of planning and evaluation, the glossary at the back of this book will help you to clarify the terms used in this chapter.

Emergency department nurses' understanding and experiences of implementing discharge planning

Aim: This paper is a report of a study conducted to describe emergency department nurses' understanding and experiences of implementing discharge planning. ---------- Background: Discharge planning in the emergency department is an important issue because of increased healthcare costs and greater emphasis on continuity of care. When executed as a collaborative process involving a multi-disciplinary team with the patient and family, discharge planning provides continuity of care for patients, less demand on hospitals, improvement in community services and in the services of other healthcare organizations. ---------- Method: The qualitative approach of phenomenography was used in this study. Thirty-two emergency department nurses were recruited between July and September 2005. Semi-structured interviews were conducted. ---------- Findings: From interviewees' descriptions of implementing discharge planning, six categories were established: implementing discharge planning as 'getting rid of my patients', completing routines, being involved in patient education, professionally accountable practice, autonomous practice and demonstrating professional emergency department nursing care. The referential meaning of implementing discharge planning 'in the outcome space' was the professional commitment to emergency department provision of effective discharge services. ---------- Conclusion: The results of this research contribute to knowledge of emergency department nurses' experience in the implementation of the discharge planning process. Key requirements for the provision of manageable discharge services both in Taiwan and worldwide highlighted by this study include adequate workloads, sufficient time, clear policies and standards of discharge planning and enhancement of professional commitment.

Discharge planning in the emergency department : a comprehensive approach

Discharge planning has become increasingly important, with current trends toward shorter hospital stays, increased health care costs, and more community-based health services. Effective discharge planning ensures the safety and ongoing care for patients,1 and it also benefits health care providers and organizations. It results in shorter hospital stays, fewer readmissions, higher access rates to post-hospitalization services, greater patient satisfaction with the discharge, and improved quality of life and continuity of care.[2] and [3] All acute care patients and their caregivers require some degree of preparation for discharge home—education about their health status, risks, and treatment; help setting health goals and maintaining a good level of self-care; information about community resources; and follow-up appointments and referrals to appropriate community health providers. Inadequate preparation exposes the patient to unnecessary risks of recurrence or complications of the acute complaint, neglect of nonacute comorbidities, mismanagement and side effects of medication, disruption of family and social life, emotional distress, and financial loss.[2], [3] and [4] The result may be re-presentation to the emergency department. It is noteworthy that up to 18% of ED presentations are revisits within 72 hours of the original visit5; many of these are considered preventable.6 It is a primary responsibility of nurses to ensure that patients return to the community adequately prepared and with appropriate support in place. Up to 65% of ED patients are discharged home from the emergency department,7 and the characteristics of the emergency department and its patient population make the provision of a high standard of discharge planning uniquely difficult. In addition, discharge planning is neglected in contemporary emergency nursing—there are no monographs devoted to the subject, and there is little published research. In this article 3 issues are explored: the importance of emergency nurses’ participation in the discharge-planning process, impediments to their participation; and strategies to improve discharge planning in the emergency department.

`Getting the city right' : the city as crucible for social reform

The connection between social reform and urban management is evident throughout the history of the city. This article maps out how ideas about social reform and social housing were established historically, during the development of the nineteenth century city. The second part examines contemporary shifts in thinking about homelessness through a case study of two Brisbane City Council initiatives in Brisbane: The Homeless Shelter Trial and Footprints along Kurilpa.