Requirements Simulation for Systems Engineers

Requirements Simulation for Systems Engineers

Manage Complexity by Simulating Requirements

Requirements specifications are at the heart of the development process. Though multiple tools are used to manage requirements, it is still common for errors to creep in at the specification stage. Validation of requirements is usually carried out after the design phase, when hardware, software and models are simulated. These HiL, SiL and MiL (Hardware, Software, Model in the Loop) simulations are performed successively to validate the embedded systems against the requirements. If there are missing and incorrect requirements, this results in costly design and test iterations.

The dynamic nature of today’s intelligent systems makes it difficult to capture requirements under various operating conditions and system states. A model-based approach advocates the modeling of operating conditions and dynamic states, related functions, and the simulation of functional requirements – to detect and rectify issues with requirements before the detail design activity. Test vectors reflecting operating conditions and dynamic system states are then generated automatically. STIMULUS, the requirements simulation solution from Dassault Systèmes adopts the model-based approach and allows you to simulate and debug the requirements to find missing requirements, identify conflicting ones etc., in exactly the same way a software developer debugs code.

For a video introduction to STIMULUS, please click here.

WHAT IF… you could validate requirements before starting the design?

Model Executable System Specifications

Model formalized textual requirements, state machines and block diagrams in a fully integrated simulation environment. Textual requirements can be allocated at each level of the system’s functional architecture. Describe operating modes and sequences of dynamic systems with state machines.

Debug and Test System Specifications

Simulate the complete system specification (requirements, state machines and block diagrams) as a whole and find specification errors before the design phase, adopting an effective requirement, and test-driven development process. Generate many execution traces that satisfy system specifications and provides powerful debugging features to analyze requirements simulation results: automatic detection and diagnosis of conflicting and missing requirements, requirements coverage, highlight of active requirements, signal monitoring, etc.

Validate Models in the Loop (MiL)

Once the behavior models and software code are built, validate the behavior against requirements. Build a test environment where requirements are turned into test observers, import behavioral models and software executables using the FMI® standard, generate numerous test vectors and run test campaigns and validate the behavior of the system under various operating scenarios. During test campaigns, compute and report comprehensive metrics on functional coverage of requirements.

Validate Control System Models

In most companies, debugging and testing of control systems is time consuming. Most often the focus is on validating the control systems using physical prototypes. However, very often engineers realize that issues have crept-in during the definition of the desired plant behavior and related requirements. It is also noted that many operating states have not been well covered by requirements and hence are not incorporated into the control models, resulting in re-work.

Considering the ever growing complexity of plant operating requirements, it is best to simulate and test the requirements to ensure validity and coverage before starting the control system design activity. Also, test vectors for various operating conditions should be automatically generated based on the use-case conditions and re-used in the controls design environment. This eliminates the need to create test-cases once again in the control design environment.

Use-cases defined in STIMULUS are used to create test vectors as text files automatically, while the requirements are turned into MATLAB® observers that can be embedded in Simulink® models.

For a video presentation of these capabilities of STIMULUS please click here.

Contact Adaptive to find out more about what 3DEXPERIENCE can do for you.

Ramesh Haldorai is Vice President, Strategic Consulting, 3DEXPERIENCE platform at Dassault Systémes.