MACHINERY FUNCTIONAL SAFETY IN A DIGITAL WORLD
Stewart Robinson MIET MInstMC, principal engineer and functional safety expert at TÜV SÜD, a global product testing and certification organisation
A
s new applications develop and become increasingly interconnected, the landscape of standardisation is changing, bringing new requirements for the functional safety of machines and process plants.
In the machine industry, the significance of functional safety has increased continuously as a result of advancing digitalisation. These technologies have contributed significantly to more efficiency and a higher degree of automation – also in terms of improved operability and profitability. However, the increasing connectivity of systems and plants, plus the growing possibilities of remote control, has seen a paradigm shift away from the prevention of access and the reliable shutdown of machines to the reliable identification of people and continued operation. Due to this trend, both possible damage events and the safety-related parts of control systems have become more complex. One example is the introduction of collaborative operation with robots, where people and machines work more closely together and which offers enormous potential for improving efficiency. The main requirement for complex semiconductors, that are used in functionally safe embedded systems, is a high degree of miniaturisation with the goal of reducing area and cost. Furthermore, modern design requires
compatibility, reusability and embedded safety features. The challenges in this domain are short innovation cycles, a high degree of design complexity and increasing integration density. These aspects have a massive impact on the assessment of device functional safety, especially as new fault models caused by new technologies must be considered. This is particularly the case for Systems-on-Chip (SoC), where dependent faults have to be evaluated, and already known failure modes, such as transient failures, take on increased relevance in the context of integration of smaller structures.
In addition, adequate verification approaches, which show the effectiveness of safety measures, must be developed. Due to massively increasing system complexity, a high-quality development and lifecycle process is therefore required to ensure a low level of systematic faults.
The assessment of design and manufacturing processes is another key factor in avoiding the consequences of systematic faults. Those using semiconductor components therefore need informative and complete documentation, in order to realise a safe and straightforward system design. This means that great care must be taken when generating the user documentation with respect to completeness of system integration. Consequently, the generic normative requirements should be interpreted and extended, based on
14 SEPTEMBER 2020 | FACTORY&HANDLINGSOLUTIONS
the current state-of-the-art and the specific technology being considered.
PEOPLE POWER
Despite great technological advances, it is ultimately organisations and people that have the responsibility of realising functionally safe products and systems. Implementation of the many different requirements of functional safety thus requires a management framework, which regulates the processes and organisation of the activities to be performed.
Functional safety management is therefore a key element of relevant functional safety standards. This includes the definition of the roles and tasks of the individuals involved, proof of their competence, and the qualification measures necessary to ensure up-to-date knowledge. Further elements that must be defined within the scope of the safety life cycle include both the type and scope of the required documentation and quality assurance. This spans the preparation of documented procedures, work instructions and checklists, as well as official signature authorisations. Recording of field experience must also be regulated, as must modification and configuration management.
Functional safety management should also have numerous interfaces with the higher-level quality management system, which is typically in place
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