Leveraging Weakly-hard Constraints for Improving System Fault Tolerance with Functional and Timing Guarantees

TL;DR

This paper introduces a novel approach using weakly-hard constraints to enhance fault tolerance in safety-critical real-time systems, ensuring timing and functional correctness despite resource limitations and faults.

Contribution

It develops a framework combining control cost analysis, worst-case analysis, simulation, and meta-heuristics to optimize fault-tolerant system design under weakly-hard constraints.

Findings

Effective control cost bounds under deadline misses

Validated approach on industrial and synthetic cases

Improved fault tolerance with timing guarantees

Abstract

Many safety-critical real-time systems operate under harsh environment and are subject to soft errors caused by transient or intermittent faults. It is critical and yet often very challenging to apply fault tolerance techniques in these systems, due to their resource limitations and stringent constraints on timing and functionality. In this work, we leverage the concept of weakly-hard constraints, which allows task deadline misses in a bounded manner, to improve system's capability to accommodate fault tolerance techniques while ensuring timing and functional correctness. In particular, we 1) quantitatively measure control cost under different deadline hit/miss scenarios and identify weak-hard constraints that guarantee control stability, 2) employ typical worst-case analysis (TWCA) to bound the number of deadline misses and approximate system control cost, 3) develop an event-based simulation method to check the task execution pattern and evaluate system control cost for any given solution and 4) develop a meta-heuristic algorithm that consists of heuristic methods and a simulated annealing procedure to explore the design space. Our experiments on an industrial case study and a set of synthetic examples demonstrate the effectiveness of our approach.