2P1-D03 等身大ヒューマノイドの状態表現に基づく失敗検知復帰ルール記述可能な行動動作システム

This paper presents a detailed discussion of a number of important issues associated with an integrated intelligent control system (IICS) using a knowledge-based approach for a flexible manufacturing cell (FMC). The architecture of the system consists of several functional modules for design, planning, sensing, control, error recovery and the actions of the cell's devices. These modules are: the CAD-based user interface; the product data model; a process planner module; a knowledge based system; a cell organiser module; the sensory system; the control module; and an error detection and recovery module. All are linked together in a structure which is based on a three level, hierarchical, intelligent-machine architecture. The developed system in total is capable of performing various manufacturing tasks without requiring any human support, even under the influence of uncertain or unexpected conditions.

The incorporation of error detection and recovery mechanisms becomes mandatory as the probability of the occurrence of transient faults increases. The detection of control flow errors has been extensively investigated in literature. However, only few works have been conducted towards recovery from control-flow errors. Generally, a program is re-executed after error detection. Although re-execution prevents faults from corrupting data, it does not allow the application to run to completion correctly in the presence of an error. Moreover, the overhead of re-execution increases prominently. The current study presents a pure-software method based on encoded signatures to recover from control-flow errors. Unlike general signature monitoring techniques, the proposed method targets not only interblock transitions, but also intrablock and inter-function transitions. After detecting the illegal transition, the program flow transfers back to the block where the error occurred, and the data errors caused by the error propagation are recovered. Fault injection and performance overhead experiments are performed to evaluate the proposed method. The experimental results show that most control flow errors can be recovered with relatively low performance overhead.

In recent years, very long instruction word (VLIW) processor has attracted much attention in that it offers a high instruction level parallelism and reduces the hardware design complexity. In this paper, we present two fault-tolerant schemes for VLIW processors. The first one is termed as test-instruction scheme which is based on the concept of instruction duplication to detect the errors. The process of test-instruction scheme consists of the error detection, error rollback recovery and reconfiguration. The second approach is called self-checking scheme which adopts the concept of self-checking logic to detect the errors. A real-time error recovery procedure is developed to conquer the errors. We implement the proposed designs of fault-tolerant VLIW processor in VHDL and employ the fault injection and fault simulation to validate our schemes. The main contribution of this research is to present the complete frameworks from error detection to error recovery for fault-tolerant design of VLIW processors. Experience learned from this investigation is that the issues of error detection and error recovery entail considering together. Without taking both issues into account simultaneously, the outcomes may lead to the improper conclusions.

This study investigates error detection and recovery for flexible assembly systems. A method for error recovery based upon an expert system is presented.

A study of generalization error in signal detection by multiple spatially-distributed and -correlated sensors is provided when the detection rule is learned from a finite number of training samples via the classical linear discriminant analysis formulation. Spatial correlation among sensors is modeled by a Gauss-Markov random field defined on a nearest neighbor graph according to inter-sensor spatial distance, where sensors are placed randomly on a growing bounded region of the plane. A fairly simple approximate expression for generalization error is derived involving few parameters. It is shown that generalization error is minimized not when there are an infinite number of sensors, but a number of sensors equal to half the number of samples in the training set. The minimum generalization error is related to a single parameter of the sensor spatial location distribution, derived based on weak laws of large numbers in geometric probability. The finite number of training samples acts like a budgeting variable, similar to a total communication power constraint.

Distributed Speech Recognition (DSR) systems rely on efficient transmission of speech information from distributed clients to a centralized server. Wireless or network communication channels within DSR systems are typically noisy and bursty. Thus, DSR systems must utilize efficient Error Recovery (ER) schemes during transmission of speech information. Some ER strategies, referred to as forward error control (FEC), aim to create redundancy in the source coded bitstream to overcome the effect of channel errors, while others are designed to create spread or delay in the feature stream in order to overcome the effect of bursty channel errors. Furthermore, ER strategies may be designed as a combination of the previously described techniques. This chapter presents an array of error recovery techniques for remote speech recognition applications. This chapter is organized as follows. First, channel characterization and modeling are discussed. Next, media-specific FEC is presented for packet erasure applications, followed by a discussion on media-independent FEC techniques for bit error applications, including general linear block codes, cyclic codes, and convolutional codes. The application of unequal error protection (UEP) strategies utilizing combinations of the aforementioned FEC methods is also presented. Finally, framebased interleaving is discussed as an alternative to overcoming the effect of bursty channel erasures. The chapter concludes with examples of modern standards for channel coding strategies for distributed speech recognition (DSR). 8.1. Distributed Speech Recognition Systems Throughout this chapter various error recovery and detection techniques are discussed. It is therefore necessary to present an overview of a complete experimental DSR system, including feature extraction, a noisy channel model, and an automatic speech recognition engine at the server end (Fig. 8.1). 2 Bengt J. Borgstrom, Alexis Bernard, and Abeer Alwan Feature Extraction Source Coding Channel Coding Channel Decoding Source Decoding Speech Recognition Client Server Noisy Channel input speech

Critical infrastructure applications provide services upon which society depends heavily; such applications require constant, dependable operation in the face of various failures, natural disasters, and other disruptive events that might cause a loss of service. These applications are themselves dependent on distributed information systems for all aspects of their operation, so survivability of these critical information systems is an important issue. Survivability is the ability of a system to continue to provide service, though possibly alternate or degraded, in the face of various types of failure and disruption. A fundamental mechanism by which survivability can be achieved in critical information systems is fault tolerance. Much of the literature on fault-tolerant distributed systems focuses on tolerance of local faults by detecting and masking the effects of those faults. I describe a direction for fault tolerance in the face of non-local faults—faults whose effects have significant non-local impact, sometimes widespread and sometimes catastrophic—where often the effects of these faults cannot be masked using available resources. The goal is to recognize these non-local faults through detection and analysis, then to provide continued service (possibly alternate or degraded) by reconfiguring the system in response to these faults. A specification-based approach to fault tolerance, called RAPTOR, is presented that enables systematic structuring of formal specifications for error detection and recovery, utilizes a translator to synthesize portions of the implementation from the formal specifications, and provides an implementation architecture supporting fault-tolerance activities. The RAPTOR approach consists of three specifications describing the fault-tolerant system, the errors to be detected, and the actions to take to recover from those errors. The RAPTOR System includes a synthesizer, the Fault Tolerance Translator, to generate implementation of code components from the specifications to perform error detection and recovery activities. In addition, a novel implementation architecture incorporates the generated code as part of an infrastructure supporting fault tolerance at both the node and system levels. Finally, the solution approach is explored and evaluated through the use of case studies and experiments in two critical infrastructure application domains.

Hard real-time systems are characterized by the execution of tasks under strict time constraints. The importance of meeting a task execution deadline makes the scheduling scheme a central issue for the correctness and reliability of such systems. While reliability is one of the objectives, it cannot be guaranteed that any system be free from faults during its operational lifetime. Thus, in systems performing critical activities, measures that provide fault tolerance should be included [2].This paper focuses on the design and evaluation of a highly reliable integrated system which consists of local and global task schedulers. Our approach to error detection and recovery problems is to utilize safety times associated with the scheduled tasks and combine local and global recovery techniques. This approach supports system level error detection and recovery for the local scheduler and affected tasks. The performance of the system in terms of the number of recovered tasks is evaluated and the results are presented.

Describes a dexterous and robust manipulation system with a multi-fingered hand. The system is composed of a real-time pose estimation of an object manipulated by the hand, a precise manipulation using fingertip with rolling contact, motion primitives for mechanical assembly, and error-recovery strategies based on the task observation function. The system architecture and experimental results are shown.

The integration of software COTS components into safety-critical real-time systems raises serious problems from a dependability viewpoint. Wrappers can be used to assist such an integration by providing additional error detection mechanisms. We recently defined a framework to automatically develop such a type of wrappers from temporal logic specifications. In this paper, we extend this framework to endow wrappers with forward error recovery capabilities based on the concept of recovery actions. Recovery actions consist of variants of basic functions of the target system that are run concurrently to help correct errors. We apply these comprehensive wrappers to a real-time COTS microkernel. Software implemented fault injection (SWIFI) is then used to evaluate the efficiency of the wrappers. This step helped identify the sets of wrappers that maximize the error detection and recovery coverage while meeting hard task deadlines.

Mobile agent systems often require sophisticated cooperation and coordination during error detection and recovery. In this paper we propose novel fault tolerance mechanisms that support co-operative exception handling in such systems. The paper demonstrates how mechanisms like these can be formally developed and analysed. We start with identifying the typical modes of failures in agents and analysing possible failure and recovery scenarios in mobile systems. Stepwise refinement is used as our formal framework for top-down development and verification. Using the framework we formally verify the essential model properties, such as interoperability, local and global state consistency and termination of error recovery. Our approach provides developers with formal generic patterns for incorporating fault-tolerance mechanisms into mobile agent systems. We also demonstrate how the results of our formal development can be instantiated and reused in developing real-world agent software.

Binary synchronous communications, in particular the line-control functions, are described. These functions are independent of the devices transmitting and receiving, the mode of transmission, and the transmission code. A mode known as transparent transmission allows the transmission of data, independent of its bit structure. The various aspects of transmission are discussed, including station control, transmission formating, error detection, and error recovery. In addition, the communication control characters are described in detail.

We propose a roll-forward error recovery technique based on multiple scan chains for TMR systems, called Scan chained TMR (ScTMR). ScTMR reuses the scan chain flip-flops employed for testability purposes to restore the correct state of a TMR system in the presence of transient or permanent errors. In the proposed ScTMR technique, we present a voter circuitry to locate the faulty module and a controller circuitry to restore the system to the fault-free state. As a case study, we have implemented the proposed ScTMR technique on an embedded processor, suited for safety-critical applications. Exhaustive fault injection experiments reveal that the proposed architecture has the error detection and recovery coverage of 100% with respect to Single Event Upset (SEU) while imposing a negligible area and performance overhead as compared to traditional TMR-based techniques.

The intensive and continuous use of high-performance computers for executing computationally intensive applications, coupled with the large number of elements that make them up, dramatically increase the likelihood of failures during their operation. The interconnection network is a critical part of high-performance computer systems that communicates and links together the processing units. Network faults have an extremely high impact because the occurrence of a single fault may prevent the correct finalization of applications. This work focuses on the problem of fault tolerance for high-speed interconnection networks by designing a fault tolerant routing method. The goal is to solve a certain number of link and node failures, considering its impact, and occurrence probability. To accomplish this task we take advantage of communication path redundancy, by means of adaptive multipath routing approaches that fulfill the four phases of fault tolerance: error detection, damage confinement, error recovery, fault treatment and continuous service. Experiments show that our method allows applications to successfully finalize their execution in the presence of several number of faults, with an average performance value of 97% with respect to the fault-free scenarios.

This paper presents the design of the AEDRQ(An Adaptive Fault Tolerance QOS), which is running on RCSM(Reconfigurable Context Sensitive Middleware) for ubiquitous networks. The AEDRQ model is proposed for supporting QoS resource errors detection-recovery in the situation-aware middleware. The AEDRQ model captures the relationships between application missions, actions, QoS requirements, and resources under dynamically changing situations. A resource error detection-recovery algorithm using the AEDRQ model is suggested. We present the utility of the AEDRQ model in a QoS resource error detection-recovery example of the VOD system. We are in process of constructing middleware components such as Resource Agent, Resource Monitoring Agent, and fault tolerance QoS Agent using the error detection-recovery model and its specification. To ensure required reliability of multimedia communication systems, AEDRQ consists of 3 steps that are an error detection, an error classification, and an error recovery.