Automotive Functional Safety
Analysis Services
exida offers the following Analysis Services which aid in compliance to ISO 26262:
Failure Mode Effects and Diagnostic Analysis
A Failure Modes and Effects Analysis (FMEA) is a systematic way to identify and evaluate the effects of different component failure modes, to determine what could eliminate or reduce the chance of failure, and to document the system in consideration. An FMEDA (Failure Modes, Effects and Diagnostic Analysis) is an FMEA extension. It combines standard FMEA techniques with extension to identify online diagnostics techniques and the failure modes relevant to safety instrumented system design.
exida uses their SILcal analysis tool to help and support hardware designers of safety-related systems to:
- carry out a detailed Failure Modes, Effects and Diagnostics Analysis (FMEDA) according to IEC 61508/ ISO 26262 with: traceable failure rates and traceable distribution of the failure rates for the different failure modes
- calculate the safety metrics like Safe Failure Fraction (SFF) or PFDavg according to the requirements of IEC 61508 or SPFM, LFM and hardware failure rate according to the requirements of ISO 26262
- generate a complete FMEDA report for each analyzed element or subsystem
- concentrate on the analysis work by offloading the development team from searching and selecting activities for failure rates and failure modes.
Fault Tree Analysis
Fault Tree Analysis (FTA) or Markov Modeling are techniques to evaluate the safety and reliability of a given system based on its architecture.
The customer and exida engineers will review the product architecture and model qualitatively and quantitatively the effect of independent and dependent failures of the units that compose the system, and determine quantitatively the violation of the safety goals (ISO) or safety functions (IEC).
The deliverable of this task is the FTA report for the safety goals (ISO) or safety functions (IEC) specified in the SRS.
Fault Insertion Test
Typically a FMEDA is supported by means of fault insertion tests where specific component failures are simulated to confirm the existence of assumed diagnostics and to determine the exact behavior in situations where that behavior is not trivial from the design.
The outcome of this service is a Fault Insertion Tests specification that meets all IEC 61508 requirements for such a document.
SILcal is an analysis tool which shall help and support hardware designers of safety-related systems. It allows tracking of critical failure modes which can be the basis for fault insertion tests.
Mechanical FMEA
The detailed mechanical Failure Modes, Effects and Diagnostic Analysis (FMEDA) is a technique used to evaluate the reliability of a given mechanical product based on the detailed mechanical drawings of the assembly
The results of a FMEDA are a set of failure rates that can be used to determine the probability of failure, and the Safe Failure Fraction (SFF) needed for a given SIL. Typically the mechanical FMEDA is supported by a design / construction FMEA to prove the robustness against sistematic design faults.
The outcome of this service is a detailed mechanical FMEDA / FMEA report that meets all IEC requirements for such a document.
Interference Freeness, Dependent Failures and Common Cause Failure (CCF)
Dependent failures and Common Cause Failures (CCF) are the most important factor for limiting the achievable IEC or ISO Target Failure Measure in redundant systems. The Common Cause Failure Analysis (CCA) is an advanced technique evaluating the behavior of redundant subsystems under expected Common Cause Initiators (CCI). It can be determined if sufficient logical and physical independence measures are in place to combat the expected dependent failures and CCI.
The customer and exida engineers will review the product architecture and evaluate the measures against dependent failures and CCI and estimate the resulting ß-factor.
The deliverable of this task are a list of safety measures to strengthen independence and sets of ß-factors for redundant subsystems.
Silcap and Fault Insertion
The Software HAZAN (Keyword-driven HAZard ANalysis) is an advanced technique evaluating the behavior of critical S/W functions under expected fault conditions. Given the expected fault conditions it can be determined if sufficient protection measures are in place to combat these fault conditions. The list of protection measures helps in creating a checklist for integration testing.
The customer and exida engineers will review the S/W architecture and source code structure, and collect arguments for detection and containment of potential systematic problems.
The deliverable of this task is the S/W HAZAN report, listing all runtime safety integrity measures that must be implemented, and a list of Fault Injection Tests.