Automated Fault Insertion and its Role in Hardware-in-the-Loop (HIL) Simulation

This short video will examine automated Fault Insertion Switching and its role in Hardware-in-the-Loop (HIL) simulation.
What is HIL? it is a technique where real signals from a controller are connected to a test system that simulates reality, making the controller think it is in the assembled product. Electronic Control Units (ECU) are used in many electronic products; an ECU usually relies on information from a set of sensors to decide how it should function. These sensors often work in hostile environments, such as a car engine bay, and failures often occur in the sensors and their interconnections due to corrosion, aging, damage or even faulty installation.
Typically, ECUs under development are exercised by a test system that simulates the real-world environment in which the ECU will operate (HIL simulation). Stimulus instrumentation simulates the ECU’s sensor inputs, and measurement instrumentation is used to capture and verify the ECU control outputs. Safety-critical controllers will usually undergo a certification process where a series of faults are introduced. The ECU response is checked to see that it operates safely and predictably.
To inject the faults, a manual patch panel is often employed. Cables are used to connect the ECU’s I/O lines to stimulus and measurement instrumentation. The I/O lines may be disconnected to simulate open-circuits or tied together to simulate short-circuits to ground, voltage sources or other I/O lines. An engineer moves the patch cables to simulate the desired fault and then measures the results. However, this arrangement has many inherent disadvantages.
One obvious issue is size, as patch panels tend to be large. The operation is also slow and prone to error, leading to a lack of repeatability. Being able to quickly and precisely reproduce a failed test condition is a significant advantage. Automating this type of test secures the best way of producing a traceable report, free from human error.
The ability to gain software control of both instrument routing and the insertion of real-time electrical faults greatly enhances the testing process. Pickering Interfaces was the first vendor to introduce PXI switching systems explicitly designed to address Fault Insertion applications. Our range of scalable solutions may be used in place of a patch panel to switch signals from simulated and real-life devices in a HILS system and can help simplify and accelerate the testing and verification required.
The principle of fault insertion is simple - the switch modules intercept wires between the test system and the ECU and either passes the signals through unchanged or add a range of fault conditions.
With a catalog of over 60 PXI Fault Insertion modules - we have a wide range of specifications to suit specific ECU I/O characteristics, including high channel counts, multiple fault buses and signal connections, current handling up to 40A and bandwidths to support high-speed differential signals such as CAN & Ethernet. The modules are compatible with real-time system software such as National Instruments LabVIEW RT & Veristand or MATLAB’s SimuLink.
To add flexibility to HILS Fault Insertion applications, we also supply a Modular Break-out system that combines small patch panels with our PXI fault insertion modules. A user can experiment by manually injecting faults into the system using the patch panel terminals. Once they are happy with the results, the test connections can be automated via the associated switch modules.
In conclusion, Fault Insertion switching is an essential feature of an ECU test and verification strategy, especially in safety-critical applications. There are many choices of modules tailored to different ECU capabilities.