A Theoretical Application of the Simulation Interface Toolkit

Embedded systems today are becoming increasingly complex with many inputs and outputs, and with outputs that depend not just on current inputs but also on history. In traditional unit testing, a component of an embedded system is tested by feeding it artificial inputs and validating its outputs against expected values. Unit testing is now inadequate in many cases and is being replaced by dynamic testing where components are tested within a full closed loop system where some portions of the system may be simulated.

For example, consider a project where you are designing an amphibious vehicle. This vehicle needs to perform within some nominal limits both at sea and on land. At sea, the vehicle will be driven by a variable speed and pitch propeller. An embedded controller needs to be designed to optimize the thrust produced by the propeller at each operating speed by varying the pitch of the propeller blades. To do this, you, the systems engineer, need to develop a dynamic model that would mimic the behavior of the physical system, and then prototype a custom controller to interact with the simulated dynamic model. This process is commonly referred to as model-based design. Once you feel comfortable with the design of the controller, it can be deployed onto the embedded system that will exist in the final product.

The next step would be to test the controller residing on the embedded system. During this step, the dynamic model of the physical system could be reused, but physical I/O and the controller running on the embedded system would replace the software model of the controller. This would allow you to test the controller before the completion of your amphibious vehicle and without running the risk of damaging the vehicle or personnel. It would also allow you to quickly test a large test matrix, including extreme conditions that the vehicle will only rarely see.

To do this real-time model based testing the National Instruments LabVIEW/RT and the LabVIEW Simulation Interface Toolkit can be leveraged. Using these tools and a dynamic model written in LabVIEW or The MathWorks Simulink©, you can begin testing your embedded system quickly. If your test matrix is relatively small, these tools may be sufficient. If not, we at MGI can take this real-time testing a step further. We have a background in model-based real-time testing, the LabVIEW control and simulation tools, and the ability to write a system specific real-time test executive that will automate your testing matrix.