A creation method of comprehensive cases and specifications for hardware and software combined test to detect undesirable events of an industrial product using HAZOP

This paper proposes a creation method of comprehensive cases and specifications for hardware and software combined test (HSCT) to detect undesirable events of an industrial product controlled by software using hazard and operability studies (HAZOP). By testing with created HSCT specifications, the proposed method detects undesirable events of the industrial product. To remove undesirable events in industrial products, it is important to confirm the behaviour of as many undesirable events as possible in HSCT. However, since the HSCT cases were manually created by engineers, the coverage of the HSCT cases was insufficient. This paper proposes a comprehensive creation method of HSCT cases and specifications to resolve the problem of insufficient coverage of HSCT cases. The following countermeasures are implemented to realize the proposed method. (1) Define the method for extracting the parameters used in HAZOP from the hardware and software specifications, and define the information necessary to create HSCT cases and specifications. (2) Prepare HAZOP guide words for HSCT. (3) Define the format of parameters and guide words and the procedure for creating HSCT cases by combining parameters and guide words. (4) Propose a creation procedure of HSCT specifications corresponding to the HSCT cases. (5) Propose an adequate HSCT procedure that includes methods (1)–(4). As a result of the application of the proposed method, 25% more adequate HSCT cases are created and 40% more undesirable events were detected in comparison with the manual creation. Additionally, the creation time was reduced by 27%.