Model-based engineering is widely used in industries to build system architectures and engineering applications to enable virtual analysis and qualifications. Within Schindler, physics-based generic system models are developed that serve as the basis for model-based validation, worst-case development to fit to purpose development, and Executable Elevator Body of Knowledge. The model captures the dynamics of the mechanical components (rope, buffer, and overspeed governor) that are driven from electrical components (motor). The motor is controlled by the behaviour model of the main elevator control. Custom Simscape™ blocks are used to accurately model the physics of mechanical components. The elevator controller, drive, and logical components are modelled using Simulink® and m scripts.
The model development cycle follows the SCRUM methodology. In a sprint of four weeks, the development focus is to improve the accuracy of physical models as well as include additional features and variants of the main controller. This generic model, which involves the various configurations in terms of elevator control components, mechanical components, and onsite installation (number of floor levels), needs to be verified prior to the sprint release. The challenge is to automate verification tests of models, which involves time-variant physical signals.
An automated test framework called Model’s Automated Test Harnesses (MATHS) is developed using Simulink Test™ to perform system-level tests and model-in-the-loop (MIL) tests for subsystem components. Simulink Test provides a good platform to create test harnesses and write corresponding test cases. With new developments, the interfaces and, to some extent, logics of the models change. Therefore, it becomes necessary to create a framework which allows the maximum reuse of the test harnesses and minimum rework on defining test cases.
