Scalable and Fault Tolerant Failure Detection and Consensus

Author(s):  
Amogh Katti ◽  
Giuseppe Di Fatta ◽  
Thomas Naughton ◽  
Christian Engelmann
2021 ◽  
Author(s):  
James Gaston

The work area of a team of small robots is limited by their inability to traverse a very common obstacle: stairs. We present a complete integrated control architecture and communication strategy for a system of reconfigurable robots that can climb stairs. A modular robot design is presented which allows the robots to dynamically reconfigure to traverse certain obstacles. This thesis investigates the implementation of a system of autonomous robots which can cooperatively reconfigure themselves to collectively travers obstacle such as stairs. We present a complete behaviorand communication system which facilitates this autonomous reconfiguration. The layered behavior-based control system is fault-tolerant and extends the capabilities of a control architecture known as ALLIANCE. Behavior classes are introduced as mechanism for managing ordering dependencies and monitoring a robot's progress through a particular task. The communication system compliments the behavioral control and iimplementsinherent robot failure detection without the need for a base station or external monitor. The behavior and communication systems are validated by implementing them ona mobile robot platform synthesized specifically for this research. Experimental trials showed that the implementation of the behavior control systems was successful. The control system provided robust, fault-tolerant performance even when robots failed to perform docking tasks while recongifuring. Once the robots reconfigure to form a chain, a different control scheme based on gait control tables coordinates the individual movements of the robots. Several successful stair climbing trials were accomplished. Improvements to the mechanical design are proposed.


2021 ◽  
pp. 1-30
Author(s):  
İ. Gümüşboğa ◽  
A. İftar

Abstract Elevator failure may have fatal consequences for fighter aircraft that are unstable due to their high manoeuvrability requirements. Many studies have been conducted in the literature using active and passive fault-tolerant control structures. However, these studies mostly include sophisticated controllers with high computational load that cannot work in real systems. Considering the multi-functionality and broad operational prospects of fighter aircraft, computational load is very important in terms of applicability. In this study, an integrated fault-tolerant control strategy with low computational load is proposed without sacrificing the ability to cope with failures. This control strategy switches between predetermined controllers in the case of failure. One of these controllers is designed to operate in a non-failure condition. This controller is a basic controller that requires very little computational effort. The other controller operates when an asymmetric elevator failure occurs. This controller is a robust fault-tolerant controller that can fly the aircraft safely in case of elevator failure. The switching is decided by a failure detection system. The proposed integrated fault-tolerant control system is verified by non-linear F-16 flight simulations. These simulations show that the proposed method can cope with failures but requires less computational load because it uses a conventional controller in the case of no failure.


2020 ◽  
Author(s):  
Alber Filba-Martinez ◽  
Salvador Alepuz ◽  
Sergio Busquets-Monge ◽  
Adria Luque ◽  
Josep Bordonau

The present paper proposes a novel device defined as an intelligent electronic fuse (iFuse) meant to be connected in series with any current-bidirectional voltage-unidirectional active switch present in a given converter. The iFuse duty is to isolate its series- associated switch from the rest of the converter circuit immediately after detecting that said switch has failed in short circuit. Nonetheless, it maintains the reverse (free- wheeling) current path originally offered by the failed switch. The failure detection is performed when the failed switch causes a shoot-through event. Therefore, the iFuse is designed to be able to block the elevated current occurring in such event. The iFuse allows increasing the fault-tolerant capability and the reliability of power converters where such qualities are hindered by switch short-circuit failures, as in converters featuring parallelized switches, neutral-point-clamped multilevel topologies, or redundant legs. The feasibility of the iFuse device is verified through experimental tests, proving that the device is able to detect the failure of its associated switch and isolate it from the rest of the converter circuit in 6 μs, while stopping short-circuit currents of up to 1 kA without incurring in harmful di/dt values.


2004 ◽  
Vol 17 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Marjan Bozinovski ◽  
Liljana Gavrilovska ◽  
Ramjee Prasad ◽  
Hans-Peter Schwefel

The session initiation protocol (SIP) is the main signaling protocol in the 3GPP IP multimedia subsystem (IMS). The SIP sessions in IMS have to be highly reliable. The developed fault-tolerant SIP call control concept includes state-sharing mechanism, failure-detection and fail-over management. The state-sharing mechanism representing the core entity in the overall system has been developed to meet the specific SIP functional features and requirements for reliability of SIP services. Theoretical analysis and measurements in a prototype implementation showed that TFTP outperforms FTP.


Author(s):  
Fady A. Abouelghit ◽  
Gehad I. Alkady ◽  
Ramez M. Daoud ◽  
Hassanein H. Amer ◽  
Ihab Adly

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