Simulators can help automotive manufacturers evaluate a wide range of factors which affect the driving experience, from the vehicle’s dynamic behavior to the driver’s interactions with the controls and instruments. In many of these simulated tests, moving images of the road are projected onto a screen with a driver seated in a vehicle mockup, but there are some circumstances when it is better if the driver uses a head-mounted display (HMD) to view the vehicle and road ahead. One example of an HMD being preferable to a screen was when Cruden helped Volkswagen Group with the assessment of numerous alternative designs for dashboard-located instruments and interiors.
For VW’s comparative tests to arrive at dependable conclusions, it was vital for the driving experience to be realistic, which meant providing the visual and vestibular cues drivers expect. This was achieved by using a 6-DOF motion driving simulator with an integrated replica of part of a VW car cabin. Cruden’s Panthera simulator software synchronized all software components and the control of the motion platform.
The simulator cabin consisted of the driver’s seat, steering wheel, pedals and dashboard. These were all positioned in precisely the same way they would be in the vehicle itself. The cabin was also made to be easily adjustable, in order to assess how well the various instrument concepts might adapt to different vehicle models. A seatbelt loader was integrated in the cabin to increase the perception feeling of braking action, and simulated sound was fed to the driver through noise-cancelling headphones which eliminated any of the background noise.
When a simulator is used for evaluating vehicle characteristics, such as handling or NVH, the road ahead is typically shown by projecting moving images onto a screen. It is acceptable for the dashboard and instruments to be representative of the real car’s without necessarily being exact replicas. But when the instrument panel itself is being assessed, the instruments must be rendered to appear exactly as they would in real life. They must be well-integrated in a fully immersive driving experience. And it is an HMD which is best-suited to this.
HMDs are not preferable in all circumstances, of course: they can feel heavy on the head and cause eye-strain, and the very act of wearing them feels unreal. When evaluating interior designs at a high rate (several per week), the immersion and flexibility becomes more important and outweighs the comfort arguments.
An HMD which shows both the moving road and the car’s instruments is straightforward enough from the driver’s perspective but providing this visual feed is technically quite complicated.
That’s because the HMD, originally intended for other uses, is engineered to work in a fixed or motionless room; the HMD then measures the movement of the driver’s head with respect to the room and the graphics software corrects the image for said movement.
However, in this case the user is sitting on top of a motion system and being moved about! In this situation, the movement measured by the HMD is not the movement required for the correction by the graphics software. To compensate for this, the HMD has to be informed which movements and accelerations are generated by the platform and which are caused by the driver’s voluntary head movements. This necessitated the addition of new logic to the render-engine software and the introduction of connections between motion platform, HMD motion measurements and rendering– the sort of complex work in which Cruden excels because of its coding expertise and world-class knowledge of required latencies.
This solution for VW was unusual in using HMD but typical of the way that simulators can accelerate vehicle development programs at the same time as cutting costs. Handcrafting different dashboards for real-world testing is elaborate, time-consuming and expensive, but in the virtual world and with a flexible mock-up, VW is now able to evaluate several different dashboards per week at relatively low cost.
For more information on how driving simulators can support your automotive research projects, please contact Dennis Marcus via firstname.lastname@example.org or on +31 20 707 4646.
An article on Cruden’s work with VW and HMD was published in ATZ magazine: Issue 11.2019: Driving Simulator with VR Glasses for Evaluation of New Interior Concepts
A technical paper, Influence of Vestibular Cues in Head-Mounted-Display-Based Driving Simulators by Bert Hartfiel (VW) and Rainer Stark (TU Berlin), was presented at DSC 2019 and is available to Driving Simulator Association (DSA) members.