Asynchronous Requests Research Articles

Interleaving Planning and Robot Execution for Asynchronous User Requests

ROGUE is an architecture built on a real robot which provides algorithms for the integration of high-level planning, low-level robotic execution, and learning. ROGUE addresses successfully several of the challenges of a dynamic office gopher environment. This article presents the techniques for the integration of planning and execution. ROGUE uses and extends a classical planning algorithm to create plans for multiple interacting goals introduced by asynchronous user requests. ROGUE translates the planner‘s actions to robot execution actions and monitors real world execution. ROGUE is currently implemented using the PRODIGY4.0 planner and the Xavier robot. This article describes how plans are created for multiple asynchronous goals, and how task priority and compatibility information are used to achieve appropriate efficient execution. We describe how ROGUE communicates with the planner and the robot to interleave planning with execution so that the planner can replan for failed actions, identify the actual outcome of an action with multiple possible outcomes, and take opportunities from changes in the environment. ROGUE represents a successful integration of a classical artificial intelligence planner with a real mobile robot.

Multiprocessor scheme with application to macro-dataflow

A method of operating a multiprocessor system consisting of a large number of processors accessing a common memory is presented. Access to the memory is performed in a deterministic manner which eliminates the need for arbitration logic. An analysis of the method is given and a comparison made against crossbar switch and common bus systems with serial daisy chain and parallel arbitration logic. The key feature of the method is that the memory offers access to locations rather than the processors making asynchronous requests. The scheme has particular application to macro-dataflow when a common memory is used to hold function parameters.

A distributed information system study

Our study model has allowed for the testing of basic support system component functions associated with bringing up a node, connecting it with other nodes, locating and bringing up the information system components, exploring various approaches to providing distributed system control and program-to-program communication services for a distributed information system, and the testing of a dynamic network directory (or directories) atth e support systems level. The study has also provided necessary walkthroughs and paper design of information system interface and data dictionary/directory requirements. Additionally, the study has provided insights into questions associated with application programs communicating with one another, with network control services, and with node control services. Included among the questions are what to do when a failure is detected, how unsolicited messages are handled, what application program changes have to be made in order to deal with such events as responsetime fluctuations, lost responses, variable length inputs, and asynchronous request coordination.

Analysis of a Shared Resource MIMD Computer Organization

In computer architecture investigations a major interest is in the analysis of organizations which explore parallelism, and therefore, may have multiple instruction and multiple data streams (MIMD). In this paper, a MIMD structure with one shared resource is analyzed for both synchronous and asynchronous request arrivals. Although the analysis is somewhat restricted, it appears that a similar approach can be used to extend the model to more general MIMD cases. Results presented for one particular set of parameters indicate that an optimum resource replication is possible such that an optimum cost performance is achieved.

Performance evaluation of some computer organisations

Recent trends in computer architecture studies tend to classify various configurations from the instruction and data stream point of view. Thus we have single instruction/single data stream (s.i.s.d.), single instruction/multiple data stream (s.i.m.d.) and finally multiple instruction/multiple data stream (m.i.m.d.) structures. Performance parameters are defined and analysed for these configurations. In the case of m.i.m.d. organisations, a simplified model has been analysed for both synchronous and asynchronous request arrivals. Results indicate the possibility of selecting an optimum amount of resource replication so that the cost utilisation is optimised.