distributed manipulation systems induce motions on objects through the application of forces at many points of contact. Current forms of distributed manipulation include multiple mobile robots, vibrating plates, activ...
详细信息
distributed manipulation systems induce motions on objects through the application of forces at many points of contact. Current forms of distributed manipulation include multiple mobile robots, vibrating plates, actively controlled arrays of air jets, and planar micro and macro-mechanical arrays of actuators. The authors have presented a new form of distributed manipulation using passive air flow fields, which has been experimentally demonstrated along with a computational method to locate equilibria. This paper presents a numerical approach to check the uniqueness of the pivot point of lifted logarithmic potentials. For objects with a unique pivot point, a squeeze-like sequential manipulation using air flow which brings the object to a unique final pose is presented and verified with experiments.
When the data rates in sensor networks are comparable to the available channel bandwidth, traditional randomized access schemes face the problem of energy inefficiency and reduced throughput due to increased MAC colli...
详细信息
When the data rates in sensor networks are comparable to the available channel bandwidth, traditional randomized access schemes face the problem of energy inefficiency and reduced throughput due to increased MAC collisions as well as the problem of unfair data delivery. We argue that under such conditions it is preferable to focus on techniques for scheduled access. We present a linear programming formulation and corresponding distributed TDMA-based scheduling algorithms to provide max-min fair collision-free bandwidth allocation to all sources. We evaluate the performance of the proposed scheduled flow technique using the Tossim/Nido network simulator for the Berkeley Mote/TinyOS platform. Our results show that under high data rate conditions, the proposed scheme significantly outperforms randomized access based schemes in terms of key metrics such as fairness, energy efficiency, throughput, and delay.
People on the move often are interested in information about their close proximity. This information can either be retrieved from static nodes or other mobile nodes spreading information via wireless technologies. Thi...
详细信息
People on the move often are interested in information about their close proximity. This information can either be retrieved from static nodes or other mobile nodes spreading information via wireless technologies. This approach to data diffusion potentially overloads the mobile device if no filtering is applied. Filtering mechanisms, however, cannot rely on the existence of a common information model among the peers. We present an approach for profile-based filtering which does not require shared knowledge among the nodes. Instead, our system can translate between competing taxonomies. It uses synonyms and a tolerant search algorithm to cope with morphological and lexical variations and structural differences of the taxonomies. A prototype of our approach was implemented and successfully tested.
Applications in the pervasive computing domain are challenged by the dynamism in which their execution environment changes, e.g. due to user mobility. As a result, applications have to adapt to changes regarding their...
详细信息
Applications in the pervasive computing domain are challenged by the dynamism in which their execution environment changes, e.g. due to user mobility. As a result, applications have to adapt to changes regarding their required resources. In this paper we present PCOM, a component system for pervasive computing. PCOM offers application programmers a high-level programming abstraction which captures the dependencies between components using contracts. The resulting application architecture is a tree formed by components and their dependencies. PCOM supports automatic adaptation in cases where the execution environment changes to the better or to the worse. User supplied as well as system provided strategies take users out of the control loop while offering flexible adaptation control.
The problem of efficient message delivery to multiple nodes has been widely studied for ad-hoc networks, be it sensor or mobile ad-hoc networks (MANETs). We are concerned with deterministic delivery guarantees, i.e. t...
详细信息
The problem of efficient message delivery to multiple nodes has been widely studied for ad-hoc networks, be it sensor or mobile ad-hoc networks (MANETs). We are concerned with deterministic delivery guarantees, i.e. the delivery ratio for any given message is guaranteed not to fall below a threshold specified for that message. This threshold can be considered to take the special case value of 100% when message delivery is guaranteed to all nodes. Guaranteeing delivery to all in a group, however desirable, often involves making a simplifying assumption that no destination node leaves the group nor crashes during an execution of the protocol. However, the nodes that make up an ad-hoc network are prone to failures and are likely to leave the group, something which undermines the validity of the assumption. We outline a protocol, called Scribble, which permits the minimum threshold to be less than 100%, thus allowing a few nodes to depart or crash during the execution. More precisely, it provides what we call k-deterministic delivery guarantees, where delivery is guaranteed to at least k destination nodes. The value of k is chosen by the application is required to be a realistic value. Such a service is called manycast.
distributed media synchronization is of ever increasing importance in the wake of an exponentially growing number of networked devices, media on demand, and user interactivity. Many protocols have been proposed to syn...
详细信息
distributed media synchronization is of ever increasing importance in the wake of an exponentially growing number of networked devices, media on demand, and user interactivity. Many protocols have been proposed to synchronize delivery of multimedia data among user groups spread over a packet network. These protocols typically focus on multimedia synchronization in small groups, may not support multimedia sessions with multiparty turn-taking patterns, are often application-specific, and do not perform well with varying network topologies. We describe the multipoint synchronization protocol (MSP) as a time coordinating mechanism that works well in a variety of group settings and for a variety of applications and network conditions, using multicast support if available. MSP is fully distributed and designed to scale to large user groups supporting turn-taking or concurrent sending and receiving. It has no central point of failure and can synchronize concurrent media streams over best-effort packet delivery networks in the absence of a global physical clock.
sensor networks are comprised of devices having the ability to communicate, compute and sense the environment. A wide range of information processing tasks has been studied for such networks, including operating syste...
详细信息
sensor networks are comprised of devices having the ability to communicate, compute and sense the environment. A wide range of information processing tasks has been studied for such networks, including operating systems, issues, architecture optimization, and distributed data processing. In this paper, we analyze and compare four different techniques to estimate the gradient of the function represented by the sensor samples. These include: (GA1) a simple device ID defined direction, (GA2) directional derivative, (GA3) polynomial approximation with a plane, and (GA4) polynomial approximation with a quadratic. We compare these based on density of devices per unit area, and noise in the position and sensed data. The interesting result is that GA3 significantly outperforms the other algorithms, although GA1 performs very well and is much easier to compute than the others.
This paper describes a reactive, distributed layered architecture for cooperation of multiple resource-bounded robots, which is utilized in mobile sensor network coverage. In the upper layer, a dynamic task allocation...
详细信息
This paper describes a reactive, distributed layered architecture for cooperation of multiple resource-bounded robots, which is utilized in mobile sensor network coverage. In the upper layer, a dynamic task allocation scheme self-organizes the robot coalitions to track efficiently in separate regions. It uses the concepts of ant behavior to self-regulate the regional distributions of robots in proportion to that of the targets to be tracked in the changing environment. As a result, the adverse effects of task interference between robots are minimized and sensor network coverage is improved. In the lower layer, the robots use self-organizing neural networks to coordinate their target tracking within a region. Quantitative comparisons with other tracking strategies such as static sensor placements, potential fields, and auction-based negotiation show that our approach can provide better coverage and greater flexibility in responding to environmental changes.
The emergence of truly ubiquitous computing, enabled by the availability of mobile, heterogenous devices that supply context information, is currently hampered by the lack of programming support for the design and dev...
详细信息
The emergence of truly ubiquitous computing, enabled by the availability of mobile, heterogenous devices that supply context information, is currently hampered by the lack of programming support for the design and development of context-aware applications. We have developed a framework which significantly eases the development of mobile, context-aware applications. The framework allows developers to fuse data from disparate sensors, represent application context, and reason efficiently about context, without the need to write complex code. An event based communication paradigm designed specifically for ad-hoc wireless environments is incorporated, which supports loose coupling between sensors, actuators and application components.
This paper presents a method for grouping 3D points into cuboids. The 3D points are extracted using multiple stereovision sensors, and the sensor fusion module performs the fusion of the data sets and the grouping of ...
详细信息
This paper presents a method for grouping 3D points into cuboids. The 3D points are extracted using multiple stereovision sensors, and the sensor fusion module performs the fusion of the data sets and the grouping of the points in a single algorithm. The fusion/grouping algorithm is scalable, being able to work using any number of sensors, including a single one. The grouping method relies on a method of transforming the 3D space so that the density of the points is kept constant, and all the points belonging to a single object are adjacent, making the grouping of points into cuboids a simple labeling problem.
暂无评论