Embedded systemsRISE provides several services for electronic hardware for use in safety-critical embedded systems.
Examples of services for electronic hardware include:
- Failure mode and effects analysis (FMEA)
- Assistance in making reliability estimates
- Functional evaluations
- Support in fault tracing
Design of the hardware platform
The design of the hardware platform is extremely important in the context of achieving functional safety (or reliability) of a control system. What happens, for example, if electrical contacts weld, or if a microprocessor spuriously starts a motor that causes some part to move? There are a number of different methods that can be used to reduce the probability of such faults resulting in a potentially dangerous situation. Examples of these methods include the use of redundant hardware architecture and well-proven and robust components.
The question that remains is ”How do I know that my hardware platform is sufficiently safe for the purpose for which I intend to use it?” This is where help is available from standards. For many products, there are product-specific standards that spell out the functional safety requirements for hardware that are widely accepted for particular products and hardware platforms. However, more general standards may have to be applied for certain products if there is no applicable product-specific standard. Common requirements that all types of standards normally include are qualitative requirements or quantitative requirements.
- Fault tolerance – how many single faults can a system withstand without external intervention or action before it becomes dangerous
- Behaviour caused by a fault – how a system behaves if a fault occurs
- Functional requirements – e.g. in respect of certain response times
Probability of a dangerous fault occurring:
- During a given period of time (Reliability)
- At a given time (Availability)
Failure mode and effects analysis (FMEA)
RISE can perform a failure mode and effects analysis on your hardware. This is normally done in order to investigate whether a fault in the electronics hardware can cause the product to react in an unexpected or incorrect manner, e.g. by making the product dangerous for the user. An FMEA consists of two parts: a theoretical part, which analyses faults and their effects on the basis of circuit or wiring diagrams, and a practical part when certain faults are applied directly to the electronics hardware. FMEA is what is known as a bottom-up method, and can be applied to all system levels in order to investigate how the surrounding components or subsystems react to failure of a particular component.
RISE can perform a reliability estimate of your electronics hardware. We can, for example, quantify the PFD (Probability of dangerous Failure on Demand) and PFH (Probability of dangerous Failure per Hour) parameters in accordance with IEC 61508. This is based on the procedures defined in IEC TR 62 380 and/or on your own experience/estimates of the fault frequency of individual electronic components. We use Markov modelling, fault tree analysis, block diagrams and other methods for reliability or availability analyses. Reliability analyses also use the commercial Reliability Workbench program from ItemSoft.
RISE can perform a functional evaluation to provide, for example, a report on whether your electronic hardware accords with your functional specification. A functional evaluation tests certain properties of the embedded system.
Has your product been on the market for a while, and has some strange fault occurred - but only sometimes, in certain places and perhaps only in a few individual items? And have you also found it difficult to replicate the fault in your own electronics laboratory? SP can provide a fault tracing service where we use our test facilities and expertise in electronics to perform a combined analysis and test investigation together with you to try to identify and/or recreate the fault.