In the fast-evolving landscape of embedded systems, where these systems are integral to critical applications like automotive, healthcare, and industrial automation, safety testing becomes most important. Safety testing is the process of evaluating embedded systems to ensure they operate reliably, meet specific safety standards, and mitigate potential risks and hazards. Here we will explore the importance of safety testing in embedded systems and touchup on key practices to enhance the robustness of these systems.
Significance of Safety Testing
Embedded systems play a pivotal role in controlling and monitoring critical functions, from managing life support systems in medical devices to controlling the navigation and braking systems in automobiles. In such contexts, a malfunction or failure could lead to severe consequences, including injuries, loss of life, or damage to property. This calls for functional safety which is defined as freedom from unacceptable risk of physical injury or of damage to the health of people either directly or indirectly. While the development aspects could have taken care of this, it is necessary for the Quality Assurance team to validate the system for functional safety. Safety testing is, therefore, a proactive approach to identifying and addressing potential hazards and risks before deployment.
Functional safety Standards
Several functional safety standards are relevant to embedded products, especially in industries where safety is a critical concern. Here are a few notable Functional safety standards:
| ISO 26262 | Road Vehicles - Functional Safety | This international standard is specific to the automotive industry and outlines the functional safety requirements for electrical and electronic systems in vehicles. It defines processes and methods for managing safety throughout the development lifecycle. |
| IEC 61508 | Functional Safety | This is a generic standard applicable to a wide range of industries. It provides a framework for the development of safety-related systems and addresses aspects like risk assessment, safety integrity levels (SIL), and safety lifecycle management |
| DO-178C | Software Considerations in Airborne Systems and Equipment Certification | This standard is used in the aerospace industry and is recognized by aviation authorities such as the FAA (Federal Aviation Administration) and EASA (European Aviation Safety Agency) |
| IEC 62304 | Software Life Cycle Processes | This is applicable to the development of software for medical devices. It specifies the lifecycle processes for the development and maintenance of medical device software, emphasizing the importance of risk management |
| ISO 13849 | Safety of Machinery | This addresses the safety of machinery, focusing on safety-related parts of control systems. It provides guidelines for the design and implementation of safety-related control functions |
| ISO 21448 (SOTIF) | Road Vehicles | Safety of the Intended Functionality (SOTIF) is an emerging standard within the automotive industry, addressing situations where the correct functioning of a system is necessary for safety, but not sufficient. It complements ISO 26262 by focusing on scenarios not covered by functional safety standards |
| EN 50128 | Railway Applications | This is a European standard applicable to the development of software for railway control and protection systems. It provides guidance on software safety integrity levels |
| ISO 14971 | Medical Devices | This is a standard for the application of risk management to medical devices. It helps organizations identify, assess, and manage risks associated with medical devices throughout their lifecycle |
| IEC 60730 | Household appliances | This is relevant for safety testing of automatic electrical controls used in household appliances. It defines requirements for ensuring the safety and reliability of these controls |
| ISO 13850 | Emergency Stop Function | This provides principles for the design of emergency stop functions, ensuring that machinery and equipment can be quickly and safely stopped in case of an emergency |
Safety Testing of Embedded Systems
It is the responsibility of QA and product ownership team to work together to ensure the embedded product is validated for necessary safety requirements. Some of the key steps in the process of safety testing of Embedded Systems are captured in teh below table.
| Hazard Analysis and Risk Assessment | Begin with a comprehensive hazard analysis to identify potential risks and failure modes. Assess the severity and probability of each hazard to prioritize mitigation efforts |
| Compliance with Safety Standards | Adhere to industry-specific safety standards, such as ISO 26262 for automotive or IEC 61508 for industrial systems. Ensure that the embedded system complies with the safety integrity level (SIL) requirements |
| Failure Mode and Effects Analysis (FMEA) | Conduct FMEA to systematically evaluate the potential failure modes of the system. Determine the effects of each failure mode on safety and prioritize mitigation strategies |
| Fault Injection Testing | Simulate faults and failures to assess how the system responds under adverse conditions. Evaluate the effectiveness of error detection and fault tolerance mechanisms |
| Reliability Testing | Test the reliability of the embedded system under normal and stressful conditions. Identify weak points, potential points of failure, and areas for improvement |
| Safety Certification | Seek safety certifications from relevant authorities or certification bodies. Demonstrate compliance with safety standards and regulations |
Challenges and Considerations
Safety testing in embedded systems comes with its own set of challenges, including the need for specialized expertise, rigorous testing environments, and adherence to evolving safety standards. Additionally, the complexity of modern embedded systems, with interconnected components and software-driven functionalities, requires a holistic approach to safety testing.
It also needs a significant investment in tools both during development - to ensure the verification is done and during testing as mechanisms need to be created to validate the system at critical levels. The testers need to be highly skilled to understand the application in depth and visualize potential hazards and run scenarios to validate them.
Conclusion
Safety testing is not just a regulatory requirement; it is a commitment to ensuring the trustworthiness of embedded systems. Whether it's the control systems in autonomous vehicles or the embedded software in medical devices, the reliability of these systems directly impacts human safety and well-being. By embracing safety testing practices, developers and organizations can build and deploy embedded systems that inspire confidence and meet the highest standards of safety and reliability. In a world increasingly reliant on embedded technologies, the assurance of safety is non-negotiable.