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.
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.
18083854
Attitude and Position Control Using Real-Time Color Tracking
A variety of sensors and positioning methods have been developed over the years. Most methods rely on active sensors (such as sonars or lasers) which have range and power restrictions, or rely on computationally complex (and often slow) methods such as recovering position from stereo or optical flow. This paper describes a system that can determine a robot's position and orientation, in all six degrees of freedom, relative to a simple passive target. The system can determine its position relative to the target from a single image frame, and process the image and calculate the position faster than a camera's frame rate (60Hz). It uses a standard, uncalibrated color video camera as its sensor. The system runs on an inexpensive microprocessor (a Motorola 68332) leaving many cycles left over. By careful design of the target and the vision processing hardware and software, we are able to selectively perceive only the relevant parts of the target, greatly simplifying and speeding all the necessary computations. The system is being developed for autonomous spacecraft station keeping and docking.
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.
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.
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.
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.
17886110
Using a single address space operating system for distributed computing and high performance
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 that spans all levels of storage and all nodes of a distributed system. These operating systems called SASOSs, have characteristics that can be used to support synchronization and coherency in a distributed system in ways that provide an improved program development environment and higher performance than that 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 synchronization and coherency support for distributed object copy set management not available in SASOSs built on stock processors. Its design, which provides direct system level support for object oriented programming includes a number of system architectural features targeted at modern distributed computing.
6569694
"Token" equilibria in sensor networks with multiple sponsors
When two sponsoring organizations, working towards separate goals, can employ wireless sensor networks for a finite period of time, it can be efficiency-enhancing for the sponsors to program their sensors to cooperate. But if each sensor privately knows whether it can provide a favor in any particular period, and the sponsors cannot contract on ex post payments, then no favors are performed in any Nash equilibrium. Allowing the sponsors to contract on ex post payments, we construct equilibria based on the exchange of "tokens" that yield significant cooperation and increase expected sponsor payoffs. Increasing the sponsors' liability is beneficial because it enables them to use more tokens
5180180
Logic programming in a fragment of intuitionistic linear logic
The intuitionistic notion of context is refined by using a fragment of J.-Y. Girard's (Theor. Comput. Sci., vol.50, p.1-102, 1987) linear logic that includes additive and multiplicative conjunction, linear implication, universal quantification, the of course exponential, and the constants for the empty context and for the erasing contexts. It is shown that the logic has a goal-directed interpretation. It is also shown that the nondeterminism that results from the need to split contexts in order to prove a multiplicative conjunction can be handled by viewing proof search as a process that takes a context, consumes part of it, and returns the rest (to be consumed elsewhere). Examples taken from theorem proving, natural language parsing, and database programming are presented: each example requires a linear, rather than intuitionistic, notion of context to be modeled adequately.<<ETX>>
14704715
A logic for reasoning with higher-order abstract syntax
Logical frameworks based on intuitionistic or linear logics with higher-type quantification have been successfully used to give high-level, modular, and formal specifications of many important judgments in the area of programming languages and inference systems. Given such specifications, it is natural to consider proving properties about the specified systems in the framework: for example, given the specification of evaluation for a functional programming language, prove that the language is deterministic or that the subject-reduction theorem holds. One challenge in developing a framework for such reasoning is that higher-order abstract syntax (HOAS), an elegant and declarative treatment of object-level abstraction and substitution, is difficult to treat in proofs involving induction. In this paper we present a meta-logic that can be used to reason about judgments coded using HOAS; this meta-logic is an extension of a simple intuitionistic logic that admits higher-order quantification over simply typed /spl lambda/-terms (key ingredients for HOAS) as well as induction and a notion of definition. The latter concept of a definition is a proof-theoretic device that allows certain theories to be treated as "closed" or as defining fixed points. The resulting meta-logic can specify various logical frameworks and a large range of judgments regarding programming languages and inference systems. We illustrate this point through examples, including the admissibility of cut for a simple logic and subject reduction, determinacy of evaluation, and the equivalence of SOS and natural semantics presentations of evaluation for a simple functional programming language.