84 research outputs found
A Rewriting Logic Approach to Stochastic and Spatial Constraint System Specification and Verification
This paper addresses the issue of specifying, simulating, and verifying
reactive systems in rewriting logic. It presents an executable semantics for
probabilistic, timed, and spatial concurrent constraint programming ---here
called stochastic and spatial concurrent constraint systems (SSCC)--- in the
rewriting logic semantic framework. The approach is based on an enhanced and
generalized model of concurrent constraint programming (CCP) where
computational hierarchical spaces can be assigned to belong to agents. The
executable semantics faithfully represents and operationally captures the
highly concurrent nature, uncertain behavior, and spatial and epistemic
characteristics of reactive systems with flow of information. In SSCC, timing
attributes ---represented by stochastic duration--- can be associated to
processes, and exclusive and independent probabilistic choice is also
supported. SMT solving technology, available from the Maude system, is used to
realize the underlying constraint system of SSCC with quantifier-free formulas
over integers and reals. This results in a fully executable real-time symbolic
specification that can be used for quantitative analysis in the form of
statistical model checking. The main features and capabilities of SSCC are
illustrated with examples throughout the paper. This contribution is part of a
larger research effort aimed at making available formal analysis techniques and
tools, mathematically founded on the CCP approach, to the research community.Comment: arXiv admin note: text overlap with arXiv:1805.0743
Path and Motion Planning for Autonomous Mobile 3D Printing
Autonomous robotic construction was envisioned as early as the ‘90s, and yet, con-
struction sites today look much alike ones half a century ago. Meanwhile, highly
automated and efficient fabrication methods like Additive Manufacturing, or 3D
Printing, have seen great success in conventional production. However, existing
efforts to transfer printing technology to construction applications mainly rely on
manufacturing-like machines and fail to utilise the capabilities of modern robotics.
This thesis considers using Mobile Manipulator robots to perform large-scale
Additive Manufacturing tasks. Comprised of an articulated arm and a mobile base,
Mobile Manipulators, are unique in their simultaneous mobility and agility, which
enables printing-in-motion, or Mobile 3D Printing. This is a 3D printing modality,
where a robot deposits material along larger-than-self trajectories while in motion.
Despite profound potential advantages over existing static manufacturing-like large-
scale printers, Mobile 3D printing is underexplored. Therefore, this thesis tack-
les Mobile 3D printing-specific challenges and proposes path and motion planning
methodologies that allow this printing modality to be realised. The work details
the development of Task-Consistent Path Planning that solves the problem of find-
ing a valid robot-base path needed to print larger-than-self trajectories. A motion
planning and control strategy is then proposed, utilising the robot-base paths found
to inform an optimisation-based whole-body motion controller. Several Mobile 3D
Printing robot prototypes are built throughout this work, and the overall path and
motion planning strategy proposed is holistically evaluated in a series of large-scale
3D printing experiments
Past, Present, and Future of Simultaneous Localization And Mapping: Towards the Robust-Perception Age
Simultaneous Localization and Mapping (SLAM)consists in the concurrent
construction of a model of the environment (the map), and the estimation of the
state of the robot moving within it. The SLAM community has made astonishing
progress over the last 30 years, enabling large-scale real-world applications,
and witnessing a steady transition of this technology to industry. We survey
the current state of SLAM. We start by presenting what is now the de-facto
standard formulation for SLAM. We then review related work, covering a broad
set of topics including robustness and scalability in long-term mapping, metric
and semantic representations for mapping, theoretical performance guarantees,
active SLAM and exploration, and other new frontiers. This paper simultaneously
serves as a position paper and tutorial to those who are users of SLAM. By
looking at the published research with a critical eye, we delineate open
challenges and new research issues, that still deserve careful scientific
investigation. The paper also contains the authors' take on two questions that
often animate discussions during robotics conferences: Do robots need SLAM? and
Is SLAM solved
Manufacturability analysis for non-feature-based objects
This dissertation presents a general methodology for evaluating key manufacturability indicators using an approach that does not require feature recognition, or feature-based design input. The contributions involve methods for computing three manufacturability indicators that can be applied in a hierarchical manner. The analysis begins with the computation of visibility, which determines the potential manufacturability of a part using material removal processes such as CNC machining. This manufacturability indicator is purely based on accessibility, without considering the actual machine setup and tooling. Then, the analysis becomes more specific by analyzing the complexity in setup planning for the part; i.e. how the part geometry can be oriented to a cutting tool in an accessible manner. This indicator establishes if the part geometry is accessible about an axis of rotation, namely, whether it can be manufactured on a 4th-axis indexed machining system. The third indicator is geometric machinability, which is computed for each machining operation to indicate the actual manufacturability when employing a cutting tool with specific shape and size. The three manufacturability indicators presented in this dissertation are usable as steps in a process; however they can be executed alone or hierarchically in order to render manufacturability information. At the end of this dissertation, a Multi-Layered Visibility Map is proposed, which would serve as a re-design mechanism that can guide a part design toward increased manufacturability
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ReSCon '11, Research Student Conference: Book of Abstracts
The fourth SED Research Student Conference (ReSCon2011) was hosted over three days, 20-22 June 2011, in the Hamilton Centre at Brunel University. The conference consisted of technical presentations, a poster session and social events. which focused on current research being conducted within the School of Engineering and Design by postgraduate research students from the School. The conference is held annually, and ReSCon plays a key role in contributing to research and innovations within the School
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