Hardware in the Loop (HIL)

Whether for performance requirements, safety certification, or software regression testing, a test system must be uniquely tailored to the device under test or class of device. Hardware in the loop is a technique for testing complex real-time systems, such as electronic control units (ECUs), that demand precision and speed by acquiring and exciting precision signals, optimized for signal bandwidth and lowest possible latency. It is used to validate control systems in a real-world setting to ensure very high levels of safety and robustness. For example, in an automotive context, this may be an electronic control unit for the electronic power steering system, suspension system, battery management system or any other vehicle subsystem.

Hardware-in-the-Loop (HIL) Challenges

To properly verify the device under test (DUT), the hardware-in-the-loop simulator used for testing must have greater accuracy, precision, and bandwidth, as well as shorter latency to be capable of emulating real-world scenarios to the DUT.

This task becomes more challenging as ECUs become more powerful. More complex models are required to meet new market requirements like efficiency, as they must replicate high power switch behavior. As the model complexity increases, so does the computation time, and consequently the demand for faster acquisition and excitation of analog inputs and outputs.

These are some of the biggest challenges we’ve identified as facing the industry today:

  • Multiple Signal Synchronization: Not only simulate analog sensors, but synchronize with other digital signals
  • Accurate Analog Response: The analog I/O should accept and replicate more complex signals
  • Model Complexity: Second- and third-order effects added into model
  • Versatility: Accommodate multiple I/O ranges
  • Reduce Analog Latency: Every tick counts, especially on the low speed side
Diagram showing hardware-in-the-loop concept

Hardware-in-the-Loop (HIL) Solutions

ADI’s broad portfolio of signal conditioning, data acquisition, signal generation, and isolation enables optimized solutions for HIL simulators. A key requirement is to measure or generate a wide range of inputs signals either in the form of voltages or currents while maintaining very low latency. Whether the system requirements call for lower power, lower noise, high density, or high accuracy, ADI has a complete signal chain solution. The links below highlight various signal chain options and recommended products and technical materials.

Current and Voltage Measurement

A common application requirement is to measure voltage or current signals over wide bandwidths. The signal chains often include protection circuitry, analog front-end signal conditioning, a single channel or multichannel ADC, voltage reference, power management, and isolation. The link below connects to signal chain options for measuring wide bandwidths up to 1 MHz optimized for noise performance to support AC and/or DC analysis.

Current and Voltage Drive

The analog output circuit must be able to generate dynamic signals with fast update rates. The voltage range, resolution and output drive strength. These signal chains often include precision DACs, isolation, power management, voltage reference, amplification/signal conditioning, and output protection.

Hardware-in-the-Loop Key Products

Illustration of AD3542R chip carrier

Ultrafast, 16-Bit Accuracy, Voltage Output DAC

The AD3542R is designed to generate multiple output span ranges and operates with a fixed 2.5 V reference. The AD3542R can be configured to achieve multiple voltage span ranges like 2.5 V, 3 V, 10 V, or ±5 V.

Learn about the AD3542R

Cutaway illustration of ADAQ23878 micromodule

Integrated Fully Differential ADC Driver With Signal Scaling

The ADAQ23878 is a precision, high speed, μModule® data acquisition solution that reduces the development cycle of a precision measurement systems by transferring the design burden of component selection, optimization, and layout from the designer to the device.

Learn about the ADAQ23878

The Road to an All EV Future: Enabling Test & Measurement Solutions for Electric Vehicles

In this webinar we will discuss some of the testing challenges with specific use case examples including low latency precision signal chains for hardware-in-the-loop applications.

View the Webcast

Electric car speeding through the city at night

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