As real as virtually possible

| Information and Communication Technology

Advanced Volvo chassis simulator and test operator

Jonathan Newell finds out how two automotive suppliers are using advanced simulation technology to test new products before they’ve left the drawing board.

Test drivers at Volvo Cars and Hyundai Commercial Vehicles no longer need to wait for prototypes of new models to be built before they sit behind the wheel to explore the limits and characteristics of their handling.

Both companies are now using advanced simulation technology linked to their Computer Aided Engineering (CAE) software and populated with mathematical models and parametric data that characterise such qualities as suspension stiffness, braking force, roll rate and oversteer in order to get a real feel for the way the vehicles drive.

Closing the feedback loop

Simulators have always been too slow in the past to be able to handle all of the data generated in a dynamic driving environment and so have been largely used so far for human factor studies and cabin ergonomics.

For Hyundai, Spanish vehicle development and test organisation, Applus IDIADA, has built a bespoke commercial vehicle simulator using the CarSim modelling environment and software from rFpro. This was achieved by closing the feedback loop as quickly as possible on all the data generated, as explained by rFpro’s Chris Hoyle, “The software provides very high bandwidth video and audio feeds to the driver at the same time as high bandwidth road surface detail to the model.”

In tests, Hyundai evaluated different vehicle configurations using professional test drivers and found a good correlation between driver perception of characteristics and actual changes made to the kinematics of the vehicle in the model.

Early design verification

For Volvo, the emphasis of its new chassis simulator is to deliver cars with unprecedented drivability, dexterity, stability and safety. These qualities will all be fine-tuned within the CAE model based on subjective feedback from the simulator pilots.

Volvo’s simulator at its Torslanda site in Sweden uses a similar VI-grade platform to the ones used at Ferrari and Porsche and can simulate different environments including the demanding, high-speed Nürburgring circuit in Germany and Volvo’s own secret proving grounds on which it tests completed vehicles.

It enables designers to establish a hands-on approach to their projects at a very early stage and thereby shorten development times without compromising on the original design objectives. Commenting on the simulator, Volvo’s Manager of Vehicle Dynamics, Stefan Karlsson said, “The beauty of the new simulator is that it provides us with the opportunity to physically experience the calculation models and evaluate them using human test drivers, rather than staring at graphs and numbers in a meeting room.”

These calculation models are complex and need to reflect the immense variability of real-world driving environments and engineers like Carl Sandberg at Volvo have to constantly monitor and adjust their calculations to make sure that bumps and lateral loads in bends result in predictable outcomes for the driver, including pitch, yaw rate and oversteer.

As part of this monitoring process, the high levels of data generated in the simulation models provide engineers with enough data to use statistical methods in an effective way for results interpretation. According to Guido Tosolin of Applus IDIADA, this visual motion cue tuning on the Hyundai simulator was vital to achieving the required results.

“Because of the high fidelity visual cueing, driver immersion was very convincing which led to good correlation between their subjective ratings and the objective data,” he said.

This “motion cue tuning” is the essential element in being able to incorporate real-world non-linearities and asymmetries into the model and bring simulation away from the world of ergonomics and into making prototype vehicle testing as real as virtually possible.

Read more about Volvo’s Volvo advanced chassis simulator including a video

Read more about Hyundai’s Hyundai commercial vehicle simulator

Jonathan Newell
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