657782
Experiences with an Architecture for Intelligent, Reactive Agents
This paper briefly describes a robot architecture that has been under development for the last eight years. This architecture uses several levels of abstraction and description languages that are compatible between levels. The makeup of the architecture helps to coordinate planful activities with real-time behaviors for dealing with dynamic environments. In recent years, many architectures have been created with similar attributes. The two features that distinguish this architecture from most of those are: 1) a variety of useful software tools have been created to help implement this architecture on multiple real robots; and 2) this architecture, or parts of it have been implemented on over half a dozen very different robot systems using a variety of processors, operating systems, effectors and sensor suites.
16341198
Global Symbolic Maps from Local Navigation
In order to navigate autonomously, most robot systems are provided with some sort of global terrain map. To make storage practical, these maps usually have a high-level symbolic representation of the terrain. The robot's symbolic map is then used to plan a local path. This paper describes a system which uses the reverse (and perhaps more natural) process. This system processes local sensor data in such a way as to allow efficient, reactive local navigation. A byproduct of this navigation process is an abstraction of the terrain information which forms a global symbolic terrain map of the terrain through which the robot has passed. Since this map is in the same format as that used by the local navigation system, the map is easy for the system to use, augment, or correct. Compared with the data from which the maps are created, the maps are very space efficient, and can be modified, or used for navigation in real-time. Experiments with this system, both in simulation, and with a real robot operating in natural terrain, are described.
7547345
Path Planning Through Time and Space in Dynamic Domains
Realistic robot problems involve navigating the robot through time as well as space. The obstacles that a robot must avoid and the pathways on which it travels are subject to changes throughout time. These changes can occur in a predictable or unpredictable fashion. This paper presents an integrated route planning and spatial representation system that allows paths to be calculated in dynamic domains. The path planner finds the "best route" through a given n-dimensional space. The "best route" is defined as the path through space-time with the best score as determined by a set of user-defined evaluation functions. The algorithm takes into account the following: Capabilities of the robot executing generated plans, traversability of space, and interactions with both predictable and unpredictable dynamic objects. The route planning algorithm is highly parallel and can be run on an SIMD (Single Instruction Multiple Data) machine in 0(p) time, where p is the length of a path. In domains with unpredictable processes, this system may be run in an incremental fashion, allowing the robot to create real-time routes along the optimal path as described by its current information. This paper will discuss: Spatial representation, an SIMD algorithm for route planning in a dynamic domain, and results from an implementation on a traditional computer architecture.
303726
Simplified navigation and traverse planning for a long-range planetary rover
This paper presents the sensor and control system for SR2, a planetary rover prototype capable of km+/day traverses through Mars-like terrain. The control system described allowed the rover to successfully navigate Mars-like terrain given a set of way-points spaced approximately 100 m apart. The control system uses input from a variety of sensors including heading, roll, pitch, an array of proximity sensors, voltage and current sensors, and a depth from stereo camera system. The control system is adequate, when combined with the rover's mobility system to make its way over or around almost all hazards a rover is likely to encounter, and to know when it is getting diverted so far off course that it needs to ask for help. In a recent field test, the robot autonomously navigated through 1.3 km of Mars like terrain to reach its goal. The SR2 is a solar powered, four-wheeled rover that masses 21 kg and fits inside a 90/spl times/65/spl times/40 cm envelope.
39419808
A Twelve-Step Program to More Efficient Robotics
Sensor abuse is a serious and debilitating condition. However, one must remember that it is a disease, not a crime.1 As such, it can be treated. This article presents a case study in sensor abuse. This particular subject was lucky enough to pull himself out of his pitiful condition, but others are not so lucky. The article also describes a 12- step behavior-modification program modeled on this and other successful case studies.
42391520
Are You Being Served?
There has been a lot of talk about service robots over the past decade, and indeed some service robots are starting to make their way into the real world; delivering food in hospitals, turning book pages for people with physical diabilities, and the like. Unfortunately, while functional, these robots perform their jobs with all the panache of machines. When people want service robots they really want “servant robots” but without the social guilt that now often accompanies the hiring of actual human servants. To do servants correctly, it is necessary to have a hierarchy in the ‘help’. Only the Dark Knight has been able to maintain style and social standing with a single servant The AAAI-97 Conference Reception is the AI community’s social event of the season. Here, as with almost all AI activities, style and social standing are everything. AI researchers work hard, and when they party, they want to be pampered. Procuring one’s own food is gauche; the AI community wants to be served. Towards this end, KIPR is creating a pair of servant robots (Capt. Peacock and Mr. Humphries) to serve and cater to their charges every gastromical need, while maintaining that old-world flavor that lets you know that while your servants may be smarter, stronger and more expensive than you, they are definitely your social inferiors.
206839040
A Look at TPS
Certain aspects of the theorem proving system TPS are described. Type theory with λ-abstraction has been chosen as the logical language of TPS so that statements from many fields of mathematics and other disciplines can be expressed in terms accessible to the system.
3091178
Using Linear Logic to Reason about Sequent Systems
Linear logic can be used as a meta-logic for the specification of some sequent calculus proof systems. We explore in this paper properties of such linear logic specifications. We show that derivability of one proof system from another has a simple decision procedure that is implemented simply via bounded logic programming search. We also provide conditions to ensure that an encoded proof system has the cut-elimination property and show that this can be decided again by simple, bounded proof search algorithms.
11687326
An Information-theoretic Learning Algorithm for Neural Network Classification
A new learning algorithm is developed for the design of statistical classifiers minimizing the rate of misclassification. The method, which is based on ideas from information theory and analogies to statistical physics, assigns data to classes in probability. The distributions are chosen to minimize the expected classification error while simultaneously enforcing the classifier's structure and a level of "randomness" measured by Shannon's entropy. Achievement of the classifier structure is quantified by an associated cost. The constrained optimization problem is equivalent to the minimization of a Helmholtz free energy, and the resulting optimization method is a basic extension of the deterministic annealing algorithm that explicitly enforces structural constraints on assignments while reducing the entropy and expected cost with temperature. In the limit of low temperature, the error rate is minimized directly and a hard classifier with the requisite structure is obtained. This learning algorithm can be used to design a variety of classifier structures. The approach is compared with standard methods for radial basis function design and is demonstrated to substantially outperform other design methods on several benchmark examples, while often retaining design complexity comparable to, or only moderately greater than that of strict descent-based methods.
5486748
Scaling internet routers using optics
Routers built around a single-stage crossbar and a centralized scheduler do not scale, and (in practice) do not provide the throughput guarantees that network operators need to make efficient use of their expensive long-haul links. In this paper we consider how optics can be used to scale capacity and reduce power in a router. We start with the promising load-balanced switch architecture proposed by C-S. Chang. This approach eliminates the scheduler, is scalable, and guarantees 100% throughput for a broad class of traffic. But several problems need to be solved to make this architecture practical: (1) Packets can be mis-sequenced, (2) Pathological periodic traffic patterns can make throughput arbitrarily small, (3) The architecture requires a rapidly configuring switch fabric, and (4) It does not work when linecards are missing or have failed. In this paper we solve each problem in turn, and describe new architectures that include our solutions. We motivate our work by designing a 100Tb/s packet-switched router arranged as 640 linecards, each operating at 160Gb/s. We describe two different implementations based on technology available within the next three years.
9952136
Using a distributed single address space operating system to support modern cluster computing
Recent 64-bit microprocessors have made a huge 18.4 quintillion byte address space potentially available to programs. This has led to the design of operating systems that provide a single virtual address space in which all code and data reside in and across all levels of storage and all nodes of a distributed system. These operating systems, called single address space operating systems (SASOSs), have characteristics that can be used to support modern cluster computing in a distributed system in ways that provide an improved program development environment and higher performance than is available from conventional operating systems. Sombrero, our SASOS design, makes use of its hardware support for object-grained protection, separate thread-related protection domains and implicit protection domain crossing to provide support for modern cluster computing which is not available in SASOSs built on stock processors. Its design, which provides direct system-level support for object-oriented programming, includes a number of features targeted specifically at modern cluster computing.