VI-grade’s New COMPACT NVH Simulator Brings the Full NVH Experience into the Office

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How do you make design decisions or sign off on vehicles at key development gateways with confidence when you cannot experience an actual prototype? This is a vexing question facing vehicle development engineers.

Across the automotive industry, physical prototype vehicles and parts are being dramatically reduced. More focus is being put on up-front design, which means more reliance on simulation and virtual prototypes. While computer-aided engineering (CAE) simulations provide abundant and valuable data, many vehicle attributes need to be experienced by real people to be fully understood. Driving simulators are the link between the data and the real world, enabling engineers, designers, executives and others to experience a vehicle long before the physical vehicle is built.

VI-grade’s driving simulator solutions are dedicated to bringing virtual prototypes into the real world where they can be accurately and reliably sensed and experienced by people—to try out new ideas, new design concepts and experience these before building a physical prototype. Using driving simulators to assess and understand virtual prototypes is the faster, more cost-effective and safer method for evaluating vehicle design concepts, data and increasing development efficiency.

NVH (Noise, Vibration and Harshness) is an attribute where virtual prototyping, and employing a driving simulator, are especially important. The sound and vibration characteristics of the vehicle are critical in conveying brand DNA, comfort and character to the driver, passengers and observers. People perceive and understand sound and vibration not as numbers, plots and graphs, but as the actual sounds and vibrations they physically experience. The easiest way to understand and make decisions is when you can directly experience the sound and vibration of a vehicle. But how is this possible without access to real, physical vehicles to drive?

Driving simulators and virtual prototypes are the answer to this question. For many years, VI-grade’s DESKTOP NVH Simulator has been providing NVH engineers with the ability to drive, experience and understand virtual NVH prototypes and NVH data. The DESKTOP NVH Simulator has been the perfect tool for virtual prototyping outside of the lab, allowing engineers to experience a vehicle’s sound in a dynamic, interactive context directly at their desk.

The DESKTOP NVH Simulator does have one limitation, however, the “V’ in NVH. Vibration perception is absent in a desktop-based simulator. For many phenomena, experiencing sound-only simulation is sufficient. For many other phenomena, however, vibration is a key part of the overall NVH experience. Sound and vibration go hand-in-hand to provide the comprehensive vehicle perception. The level of vibration frequently affects the perception of sound, and vice versa. People perceive sound and vibration holistically, and the two are inextricably connected as far as human perception is concerned.

For example, when assessing the engine idle vibration level, the perceived level of “vibration” can be altered simply by changing the corresponding sound level. Increase the sound level and the perception of vibration gets worse; decrease the sound level, and the perception is that the vibration is lower – all while holding the actual vibration constant. The ability to understand these relationships is key to setting targets and performing target trade-offs in vehicle development.

There are three trends in the automotive industry that are putting increased focus and importance on vehicle vibration and NVH overall:

1. The move towards electric vehicles (EVs).
2. The rapid evolution and adoption of ADAS and AV features.
3. The push for ever lighter-weight vehicles.

The move towards EVs means that there is less masking from the traditional IC-engine, which makes road vibration and sound more obvious. Increasing progress of ADAS and AV features mean less of the driver’s attention is tied up in driving the vehicle, and more attention is available for noticing vibration and sound of the vehicle. And finally, the increased emphasis on reduced vehicle weight, to allow for extended range and fuel economy, means that vehicles are more susceptible to higher levels of noise and vibration.

Combine these factors with the reduction in the number of physical prototypes available for testing, and NVH engineers are facing bigger challenges than ever before. It is a challenge to provide a demanding market with quiet, pleasing vehicles free from sound and vibration problems, which embody the character and the brand DNA of the specific vehicle.

VI-grade’s STATIC NVH Simulator addresses the vibration limitation present in the DESKTOP NVH Simulator by adding vibration to the NVH experience. The STATIC NVH Simulator delivers comprehensive, calibrated, multi-axial independent vibration at all driver touch points. Several VI-grade STATIC NVH Simulators have been installed worldwide, and the VI-grade SimCenter Millbrook features a STATIC NVH Simulator based on a Bentley Continental GT.

In the STATIC NVH Simulator, the vibration and sound systems are integrated into a full vehicle shell, with a large, wrap-around visual screen, providing a high level of immersion and realism for the NVH driving simulation experience. The STATIC NVH Simulator looks and performs like a real car, in a static laboratory setting. This immersive experience comes at a price—a relatively large space is required for the full-size vehicle body and wrap-around screen, and the corresponding financial costs.

Increasingly, NVH engineers at OEMs and suppliers have needed a driving simulator that provides both the fully realistic vibration at all driver touch points that engineers need in order to comprehensively execute full NVH testing, combined with the small size of a DESKTOP NVH simulator to address space constraints.

Unfortunately, this combination of features and performance in an engineering-grade driving simulator has been elusive. Enter VI-grade’s new COMPACT NVH Simulator, combining the highly precise vibration and sound experience available in the STATIC NVH Simulator in a much smaller footprint, easily accommodated in an engineering office and at a much lower price point than the STATIC NVH Simulator.

The new COMPACT NVH Simulator was first announced at VI-grade’s Zero Prototypes Summit on May 20^th, 2021, and officially launched at the SAE Noise and Vibration Conference and Exhibition on September 7^th, 2021.  It is a unique simulator that addresses the growing need among development and CAE engineers at both OEMs and suppliers to fully and accurately experience vibration at all driver touch points, together with sound, in a small footprint.

The COMPACT NVH simulator provides accurate, calibrated, multi-axial vibration at the seat, steering wheel and floor pan. Further, each axis of the seat, steering wheel and floor pan can be independently controlled, and each is independent from the others, which eliminates crosstalk. This means that when the steering wheel vibrates, it does so completely independently from the seat; the seat does not vibrate due to inputs to the steering system or vice versa. This provides engineers with the ability to understand tradeoffs between vibration levels at driver touch points, as well as sound levels.

All NVH Simulator software capabilities utilized for the DESKTOP NVH Simulator are also fully applied to the COMPACT NVH Simulator, with the added capability of vibration. This lets engineers easily:

• Switch between vehicle models to perform A/B comparisons.
• Instantly turn vehicle component sounds on or off.
• Modify component parts of the sound or vibration in real-time.
• Evaluate all of these while driving the virtual prototype in the COMPACT NVH Simulator.

Carbon fiber is used extensively in the COMPACT NVH Simulator to achieve an extremely stiff structure suitable to delivering controlled, accurate vibration to the evaluator. The frame, and even the steering wheel, is composed of carbon fiber ensuring no modes of vibration of the frame or steering wheel affect the response, enabling accurate vibration response and experience.

Multiple electrodynamic shakers are utilized in the design to provide the capability for high levels of vibration across a wide frequency range. In fact, the vibration system of the COMPACT NVH Simulator is essentially identical to that of the STATIC NVH Simulator. And a built-in touch-screen interface enables the evaluators to easily control the simulator and provide feedback on the virtual prototypes and vehicles they experience.

The COMPACT NVH Simulator can be applied to numerous areas, providing realistic evaluation of road noise and vibration on various surfaces, road impacts, powertrain NVH phenomena like cylinder deactivation, engine start/stop, idle, lugging boom and many others.

VI-grade's Director of NVH Solutions, Dave Bogema, discusses enabling a complete noise, vibration and harshness experience with the COMPACT NVH Simulator.

To learn more about the Compact NVH Simulator, visit VI-grade and check out their webinar.