Hardware in the Loop

What Is Hardware in the Loop?

Hardware in the Loop is a method for testing control systems using simulated actual inputs. In automotive scenarios, it is handy during the development of electronic control units (ECUs), ensuring that they can handle a huge variety of driving situations. Automotive software is becoming increasingly complex, and as emerging features such as self-driving become more sophisticated, it is imperative to reduce the risk of controller faults. Hardware in the Loop testing facilitates this process.

Benefits of Hardware in the Loop

Automotive systems are mission-critical. Many are essential for safety and need to function reliably during operation. But modern cars now have a vast array of sensors, including cameras, ultrasonics, radar, LiDAR, temperature and more. This is why Hardware in the Loop testing is so valuable. It allows new ECU designs and their associated software to be assessed under various simulated conditions for performance and durability.

Although these assessments could be made using a complete actual vehicle and previously were in simpler eras of vehicle design, Hardware in the Loop testing reduces the cost and speeds up the process. It is also a highly flexible and available system because the reduced overhead can enable more comprehensive, more frequent assessments. Hardware in the Loop testing can reduce time to market and increase safety.

Where testing to destruction is required, simulating this rather than destroying an actual product will be vastly less expensive. Testing human-machine interfaces can run through many different configurations for users to try so that an optimal design can be discovered more quickly. Some testing might not be legally performed using vehicles on real roads, such as for autonomous vehicle systems. Hardware in the Loop can deliver sufficient regulatory approval for road testing a mature product with most potential problems already ironed out.

Examples of Hardware in the Loop

Hardware in the Loop testing is used in a wide variety of areas of automotive production:

  • Algorithm and software development which could include motor performance management, anti-lock braking control system testing or the improvement of electronic stability control. An emerging application is the development of autonomous driving capabilities.
  • Hardware validation, to validate for operation within design parameters or regulatory constraints.
  • Safety validation, to test control systems against potential danger scenarios to ensure the design will deliver the required level of passenger, pedestrian, and cyclist safety.
  • Fault investigation, to investigate an automotive system with driving problems under various conditions to discover the causes and develop a fix.

How Hardware in the Loop Works

Hardware in the Loop testing involves emulated sensors and actuators, which provide the interface between the system under test and the simulated situation. The emulations replicate real-world feedback. The sensors provide inputs, which the system under test then reacts to by delivering actuator outputs. This results in changes in values for the simulation, which will produce new emulated sensor inputs. The results are then assessed against requirements.

For example, an Advanced Driver-Assistance System (ADAS) will be operated in various simulated weather, terrain, and traffic conditions (providing a range of inputs). The system's behavior (outputs) will then be assessed to ensure the ADAS provides the intended level of performance and safety, such as stopping sufficiently quickly when a car in front brakes unexpectedly in heavy rain.

Hardware in the Loop Vs. Platform Testing

Traditionally, automotive controllers were designed around specifications and installed in vehicles to test their functionality. If issues were identified, this would lead to a redesign of the component. Hardware in the Loop testing enables many iterations of assessment before a final stage of real-world physical platform testing. With highly complex systems like modern ADAS and autonomous driving, the number of sensors and range of conditions necessitates many design iterations, making Hardware in the Loop and Software in the Loop testing the only cost-effective routes for development.
The QNX® Hypervisor is a real-time, Type 1 hypervisor that offers virtualization technology and enables the secure separation of multiple operating environments on a single SoC. QNX Hypervisor brings containers to connected automobiles as a way to segment non-safety applications from critical systems.

Check Out Our Other Ultimate Guides

Structural Dependency
Learn about software-defined vehicles, including their benefits and architecture.
Structural Dependency
Covers topics such as embedded systems protection, security exploits and mitigation, and best practices
Structural Dependency
Learn how cloud computing for automotive works and its benefits.
Read the Guide
Structural Dependency
Defines autonomous systems and the various levels of autonomy
Read the Guide