System and functional safety of products and processes is defined by standards that specify safety requirements, safety objectives and risk analysis procedures. There are several different methods, we illustrated the differences between them on the example of a rotary magnetic encoder.
The thesis describes linear and rotary encoders, incremental and absolute encoders, coding tracks, and magnetoresistive and Hall sensors. The main characteristics of the product AksIM-4 on which the analysis was conducted are listed. Some standards for the functional safety of electrical and electronic devices are introduced, such as IEC 61508, ISO 26262, IEC 61131-6, and ISO 13849.
This is followed by a presentation of risk analysis tools. The FMECA, HAZOP and FTA methods as well as their procedures, characteristics, advantages and disadvantages are described with some examples of obtaining a risk assessment.
An FMECA and HAZOP analysis was performed for LED indicator and sensor on the readhead. Procedures and results are presented in the form of tables and block diagrams. A failure tree of an FTA is shown for the failure "the sensor has no magnetic field information of the magnetic ring".
The thesis compares the results of FMECA and HAZOP analyses and two approaches to the risk assessment, by addition and by multiplication. The role of results in preventing failures and improving product design is explained.
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