12648516
Experiments in impulsive manipulation
In this paper, we present the results of our experimental effort in one form of impulsive manipulation: tapping. Our previous work studied the mechanics of tapping a planar object which then slides on a support surface, coming to rest due to friction. This work addresses the practical issues in creating a system which uses this mode of manipulation. We begin with the design of tapping devices-end effecters designed to deliver an impulse to an object, and report some of the issues we have found to be important in their design. Our next step was to perform single-tap experiments in order to fit and evaluate the models of impact and sliding. These experiments have shown that objects rotate less than predicted; we have found that the addition of a scaling factor for the torque due to friction enables the models to predict object motion reasonably well. In order to do positioning experiments, we developed a number of planning methods (or feedback control strategies) to compensate for errors in modeling, parameters, and actuation. These planning methods were successfully used to demonstrate a positioning task. We also have experimentally demonstrated that tapping can be used to position an object more precisely than the manipulator can position the tapping device. We offer some sensitivity analysis in support of this result.
416932
Parts Feeding on a Conveyor with a One Joint Robot
Abstract. This paper explores a method of manipulating a planar rigid part on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for feeding parts in industrial automation applications. In this paper we develop a model of this system and of a variation which requires no sensing. We have been able to characterize these systems and to prove that they can serve as parts feeding devices for planar polygonal parts. We present the planners for these systems and describe our implementations.
17487285
A tapping micropositioning cell
Describes the use of tapping actuators in a "micropositioning cell." Tapping actuators are fixed (both in position and orientation) about the perimeter of the cell. A part in the cell can be precisely positioned by firing a sequence of tapping actuators (sensing the position of the object after each tap for feedback control). Such a system could be used for micropositioning tasks or in parts feeding applications. We show the controllability of this system for circular parts, describe an algorithm to position these objects, and present the results of simulated experiments. We conclude with some future directions and address the issues in extending this work to more efficient algorithms that work on a broader class of parts.
1537043
Topological Map Merging
When multiple robots cooperatively explore an environment, maps from individual robots must be merged to produce a single globally consistent map. This is a challenging problem when the robots do not have a common reference frame or global positioning. In this paper, we describe an algorithm for merging embedded topological maps. Topological maps provide a concise description of the navigability of an environment, and, with measurements easily collected during exploration, the vertices of the map can be embedded in a metric space. Our algorithm uses both the structure and the geometry of topological maps to determine the best correspondence between maps with single or multiple overlapping regions. Experiments with simulated and real-world data demonstrate the efficacy of our algorithm.
2142354
Mechanics, Planning, and Control for Tapping
We present analysis and experimental demonstration of manipulation by tapping. Our problem domain is positioning planar parts on a support surface by a sequence of taps; each tap imparts some initial velocities to the object, which then slides until it comes to rest due to friction. We formulate the mechanics of tapping for circular axisymmetric objects, show how to plan a single tap and a sequence of taps to reach a goal configuration, and present feedback control methods to robustly accomplish positioning tasks. With these methods, we have experimentally demonstrated positioning tasks using tapping, including high-precision positioning tasks in which the object is positioned more precisely than the tapping actuator. We show stability and sensitivity analysis in support of these results.
7757717
A kernel autoassociator approach to pattern classification
Autoassociators are a special type of neural networks which, by learning to reproduce a given set of patterns, grasp the underlying concept that is useful for pattern classification. In this paper, we present a novel nonlinear model referred to as kernel autoassociators based on kernel methods. While conventional non-linear autoassociation models emphasize searching for the non-linear representations of input patterns, a kernel autoassociator takes a kernel feature space as the nonlinear manifold, and places emphasis on the reconstruction of input patterns from the kernel feature space. Two methods are proposed to address the reconstruction problem, using linear and multivariate polynomial functions, respectively. We apply the proposed model to novelty detection with or without novelty examples and study it on the promoter detection and sonar target recognition problems. We also apply the model to mclass classification problems including wine recognition, glass recognition, handwritten digit recognition, and face recognition. The experimental results show that, compared with conventional autoassociators and other recognition systems, kernel autoassociators can provide better or comparable performance for concept learning and recognition in various domains.
11481204
Scheduling of MPI-2 one sided operations over InfiniBand
MPI-2 provides interfaces for one sided communication, which is becoming increasingly important in scientific applications. MPI-2 semantics provide the flexibility to reorder the one sided operations within an access epoch. Based on this flexibility, in this paper we try to improve the performance of one sided communication by scheduling one sided operations. We have come up with several re-ordering and aggregating schemes to achieve better network utilization. We have evaluated these schemes on both PCI-X and PCI-Express platforms. With re-ordering scheme, we see an improvement in the throughput up to 76%, latency up to 40%. With aggregation scheme, we observe an improvement of 44% and 42% for MPI/spl I.bar/Put and MPI/spl I.bar/Get latency respectively on PCI-Express platform.
21933462
Multi-media semantics contextualisation for knowledge-oriented e-learning
Existing e-learning technical solutions are more focused on content packaging rather than semantics management, which is one of the keys to knowledge-oriented e-learning. This paper presents a context-based approach to address the challenging semantics management issue by contextualising the semantics of multimedia learning resources at different levels. A prototype of semi-automatic multimedia semantics generation and editing tool - CONMAN shows the basic idea of the approach in practice.
1603873
Application-Transparent Checkpoint/Restart for MPI Programs over InfiniBand
Ultra-scale computer clusters with high speed interconnects, such as InfiniBand, are being widely deployed for their excellent performance and cost effectiveness. However, the failure rate on these clusters also increases along with their augmented number of components. Thus, it becomes critical for such systems to be equipped with fault tolerance support. In this paper, we present our design and implementation of checkpoint/restart framework for MPI programs running over InfiniBand clusters. Our design enables low-overhead, application-transparent checkpointing. It uses coordinated protocol to save the current state of the whole MPI job to reliable storage, which allows users to perform rollback recovery if the system runs into faulty states later. Our solution has been incorporated into MVAPICH2, an open-source high performance MPI-2 implementation over InfiniBand. Performance evaluation of this implementation has been carried out using NAS benchmarks, HPL benchmark, and a real-world application called GROMACS. Experimental results indicate that in our design, the overhead to take checkpoints is low, and the performance impact for checkpointing applications periodically is insignificant. For example, time for checkpointing GROMACS is less than 0.3% of the execution time, and its performance only decreases by 4% with checkpoints taken every minute. To the best of our knowledge, this work is the first report of checkpoint/restart support for MPI over InfiniBand clusters in the literature
40011370
Contextual Knowledge Representation, Retrieval and Interpretation in Multimedia e-Learning
In highly interactive modern multimedia e-learning environments, current e-learning support products based on basic information management technologies are not able to support semantic-based knowledge management and communication beyond heterogeneous multimedia learning resources. Much of desired intelligent e-learning functionality needs further research and technical developments with semantic context-awareness. Proposed framework in this paper is expected to improve the current isolated learning management status, by making the most use of related learning information, and enabling flexible knowledge retrieval, communication and transfer between instructors and learners. To work with related existing e-learning content description standards and enable a semantic-based interactive learning environment, this paper explores a set of novel contextual knowledge discovery and reuse techniques. Based on knowledge communication model analysis in university e-learning, a contextual knowledge representation model is presented. Corresponding knowledge retrieval and semantic knowledge interpretation techniques are presented afterwards towards supporting pedagogical learning approaches such as scenario-based learning.