Departmental Papers (CIS)

Document Type

Conference Paper

Date of this Version

4-2011

Comments

The 14th International Conference on Hybrid Systems: Computation and Control (HSCC'11) Chicago April 12 - 14, 2011.
HSCC'11 is part of the 4th Cyber Physical Systems Week (CPSWeek)

Abstract

We examine the problem of reliable networked control when the communication channel between the controller and the actuator periodically drops packets and is faulty i.e., corrupts/alters data. We first examine the use of a standard triple modular redundancy scheme (where the control input is sent via three independent channels) with majority voting to achieve mean square stability. While such a scheme is able to tolerate a single faulty channel when there are no packet drops, we show that the presence of lossy channels prevents a simple majority-voting approach from stabilizing the system. Moreover, the number of redundant channels that are required in order to maintain stability under majority voting increases with the probability of packet drops. We then propose the use of a reputation management scheme to overcome this problem, where each channel is assigned a reputation score that predicts its potential accuracy based on its past behavior. The reputation system builds on the majority voting scheme and improves the overall probability of applying correct (stabilizing) inputs to the system. Finally, we provide analytical conditions on the probabilities of packet drops and corrupted control inputs under which mean square stability can be maintained, generalizing existing results on stabilization under packet drops.

Keywords

Reliability, Security, Design, Algorithms, Theory, Networked Control, Reputation, Majority Voting, Stability Analysis

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Date Posted: 03 May 2011

This document has been peer reviewed.