451273
Comparing the usefulness of video and map information in navigation tasks
One of the fundamental aspects of robot teleoperation is the ability to successfully navigate a robot through an environment. We define successful navigation to mean that the robot minimizes collisions and arrives at the destination in a timely manner. Often video and map information is presented to a robot operator to aid in navigation tasks. This paper addresses the usefulness of map and video information in a navigation task by comparing a side-by-side (2D) representation and an integrated (3D) representation in both a simulated and a real world study. The results suggest that sometimes video is more helpful than a map and other times a map is more helpful than video. From a design perspective, an integrated representation seems to help navigation more than placing map and video side-by-side.
43673902
Coordinated target assignment and intercept for unmanned air vehicles
Presents an end-to-end solution to the battlefield scenario where M unmanned air vehicles are assigned to strike N known targets, in the presence of dynamic threats. The problem is decomposed into the subproblems of (1) cooperative target assignment, (2) coordinated UAV intercept, (3) path planning, and (4) feasible trajectory generation. The design technique is based on a hierarchical approach to coordinated control. Detailed simulation results are presented.
12614052
Learning haptic feedback for guiding driver behavior
Information about the driving state can be conveyed to automobile drivers through force feedback signals sent via the pedals and steering wheel. Because the set of possible haptic signals and driver responses is huge, it is desirable to automatically learn which signals are most useful to drivers. Thus, it is instructive to explore how machine learning techniques can be used as a step in the design of a haptic interface system. In this paper, we present a learning algorithm that learns useful haptic feedback and apply the algorithm to learning feedback for automobile drivers. We present evidence to show that the algorithm is sensitive enough to learn useful feedback under some circumstances, but that its scope may be limited by people's ability to act as admittance controllers.
29722627
A theory of satisficing decisions and control
The existence of an optimal control policy and the techniques for finding it are grounded fundamentally in a global perspective. These techniques can be of limited value when the global behaviour of the system is difficult to characterize, as it may be when the system is nonlinear, when the input is constrained, or when only partial information is available regarding system dynamics or the environment. Satisficing control theory is an alternative approach that is compatible with the limited rationality associated with such systems. This theory is extended by the introduction of the notion of strong satisficing to provide a systematic procedure for the design of satisficing controls. The power of the satisficing approach is illustrated by applications to representative control problems.
13562077
Satisficing Equilibria: A Non-Classical Theory of Games and Decisions
Satisficing, or being “good enough,” is the fundamental obligation of rational decision makers. We cannot rationally choose an option, even when we do not know of anything better, unless we know it is good enough. Unfortunately, we are not often in the position of knowing that there could be no better option, and hence that the option must be good enough. A complete search through all logical possibilities is often impractical, particularly in multi-agent contexts, due to excessive computational difficulty, modeling complexity, and uncertainty. It can be equally impractical, if it is even possible, to determine the cost of the additional required search to find an option that is good enough. In a departure from the traditional notion of satisficing as a species of bounded rationality, satisficing is here redefined in terms of a notion of intrinsic rationality. Epistemic utility theory serves as the philosophical foundation of a new praxeological decision-making paradigm of satisficing equilibria that is applicable to both single- and multiple-agent scenarios. All interagent relationships are modeled by an interdependence function that explicitly accommodates both self and group interest, from which multilateral and unilateral selectability and rejectability mass functions can be derived and compared via the praxeic likelihood ratio test.
6463761
Snapshots for semantic maps
A significant area of research in mobile robotics is in the local representation of a remote environment. In order to include a human in a mobile robot task it becomes important to present the remote information efficiently to a human. A relatively new approach to information presentation is semantic maps. Semantic maps provide more detail about an environment than typical maps because they are augmented by icons or symbols that provide meaning for places or objects of interest. In this paper we present snapshot technology as a means to take pictures from the real world and store them in a semantic map. To make the snapshots and semantic map available to an operator, we identify and discuss general attributes for useful displays and present a mixed reality 3D interface that meets the requirements. The interface and snapshot technology are validated through experiments in real and simulated environments.
8504456
Notarized Federated Identity Management for Web Services
We propose a notarized federated identity management model that supports efficient user authentication when providers are unknown to each other. Our model introduces a notary service, owned by a trusted third-party, to dynamically notarize assertions generated by identity providers. An additional feature of our model is the avoidance of direct communications between identity providers and service providers, which provides improved privacy protection for users. We present an efficient implementation of our notarized federated identity management model based on the Secure Transaction Management System (STMS). We also give a practical solution for mitigating aspects of the identity theft problem and discuss its use in our notarized federated identity management model. The unique feature of our cryptographic solution is that it enables one to proactively prevent the leaking of secret identity information.
14119951
Drawing Planar Graphs with Circular Arcs
In this paper we address the problem of drawing planar graphs with circular arcs while maintaining good angular resolution and small drawing area. We present a lower bound on the area of drawings in which edges are drawn using exactly one circular arc. We also give an algorithm for drawing n-vertex planar graphs such that the edges are sequences of two continuous circular arcs. The algorithm runs in O(n) time and embeds the graph on the O(n) × O(n) grid, while maintaining θ(1/d(v)) angular resolution, where d(v) is the degree of vertex v. Since in this case we use circular arcs of infinite radius, this is also the first algorithm to simultaneously achieve good angular resolution, small area and at most one bend per edge using straight-line segments. Finally, we show how to create drawings in which edges are smooth C 1-continuous curves, represented by a sequence of at most three circular arcs.
15155591
Straight-skeleton based contour interpolation
In this paper we present an efficient method for interpolating a piecewise-linear surface between two parallel slices, each consisting of an arbitrary number of (possibly nested) polygons that define 'material' and 'nonmaterial' regions. This problem has applications to medical imaging, geographic information systems, etc. Our method is fully automatic and is guaranteed to produce non-self-intersecting surfaces in all cases regardless of the number of contours in each slice, their complexity and geometry, and the depth of their hierarchy of nesting. The method is based on computing cells in the overlay of the slices, that form the symmetric difference between them. Then, the straight skeletons of the selected cells guide the triangulation of these cells. Finally, the resulting triangles are lifted up in space to form an interpolating surface. We provide some experimental results on various complex examples to show the good and robust performance of our algorithm.
1293647
Competitive tree-structured dictionaries
In this note we describe a general technique for making treestructured dynamic dictionaries adapt to be competitive with the most efficient implementation, by using potential energy parameters and a simple partial rebuilding scheme. Introduction. On-line algorithms deal with optimizing the performance of operation sequences (e.g., see [4, 9]). Such algorithms are desired to be -competitive [4], for some parameter , where is an upper bound on the ratio of the costs of the solution defined by the on-line algorithm and an oracle’s algorithm. In this paper we are interested in dictionary data structures that are competitive in this same sense. Our Results. We present a simple adaptive tree-based dictionary structure that is balanced and competitive. Our approach is based on a potential energy parameter stored at each node in the tree. As updates and queries are performed, the potential energy of tree nodes are increased or decreased. Whenever the potential energy of a node reaches a threshold level, we rebuild the subtree rooted at that node. We show that, in spite of its conceptual simplicity, such a scheme is constant-ratio competitive with a static oracle using a priori knowledge of the operation distribution. Related Prior Work. Besides general work for on-line algorithms (e.g., see [4, 9]) and data structures that use partial rebuilding [7], there has been some prior work on methods for adapting data structures to the way in which they are being used. Most previous data structure competitive analyses have been directed at simple linked-lists structures, with “move-to-front” heuristics applied [9]. Work on other adaptive data structures includes splay trees [10], which perform a sophisticated move-to-root heuristic, but perform many rotations with each access. There is also the randomized binary search tree of Seidel and Aragon [8], which performs random structural changes with each access and can adapt in an expected, probabilistic sense based on data structure usage. Energy-Balanced Binary Search Trees. A dictionary holds pairs of ordered keys and elements, subject to update and query operations. A common way of implementing the dictionary ADT is to use a binary search tree, which maintains balance by local rotation operations. Typically, such rotations are fast, but if the tree has auxiliary structures, rotations are often slow. Standard binary search trees, such as AVL trees [1], red-black trees [3], scapegoat trees [2], or weight-balanced trees [6], maintain balance, but do not adapt themselves based on the distribution of accesses and updates. Splay trees [10], on the other hand, adapt (in an asymptotic sense), but perform a large number of rotations with each access. Finally, randomized binary search trees [8], have good expected behavior but offer no worst-case guarantees on per-
2560451
Teaching data structure design patterns
In this paper we present an approach for teaching the Freshman-Sophomore introduction to data structures course (CS2) in a way that provides an introduction to object-oriented software engineering patterns in addition to the theory of data structures. We survey in this paper several design patterns and describe how they can be naturally integrated in the CS2 curriculum.