Sanntidskritiske

Sanntidskritiske describes systems or tasks that require guaranteed timing behavior, where meeting defined deadlines is essential for correct operation. The term is used to emphasize the real-time nature of responses, as opposed to purely functional correctness. In practice, sanntidskritiske considerations cover not only correctness of results but also when those results are produced.

Real-time systems are commonly categorized as hard real-time or soft real-time. In hard real-time systems, missing a deadline constitutes a system failure and can have catastrophic or safety-critical consequences. In soft real-time systems, occasional deadline misses are allowed but degrade performance or quality of service. The choice between these categories drives decisions about architecture, scheduling, and verification.

Typical domains include embedded systems in automotive and aerospace, industrial automation, robotics, medical devices, and consumer electronics with strict timing requirements. Characteristics of sanntidskritiske systems include determinism, predictable timing, low and bounded latency, and robust fault handling. Key design concepts involve timing analysis, worst-case execution time estimation, and scheduling algorithms such as rate-monotonic and earliest-deadline-first. Time-triggered architectures and time determinism are often preferred in safety-critical contexts.

Verification and safety considerations are central. Timing analysis, formal verification, simulation, and hardware–software co-design help ensure adherence to deadlines. Redundancy, watchdogs, and fail-operational strategies are common to improve reliability. International standards frequently guiding development include ISO 26262 for automotive safety, IEC 61508 for functional safety, DO-178C/DO-254 for aerospace software and hardware, and IEC 62304 for medical device software.