Vibracoustic addresses emerging NVH challenges unique to autonomous vehicles

Driver and passengers have a heightened perception of NVH issues when the control of steering, acceleration and braking is transferred to the vehicle in partly or fully autonomous vehicles.

Vibracoustic, an industry leader in automotive NVH solutions is researching and developing new solutions to manage NVH in autonomous vehicles - likely a critical factor to acceptance and mass adoption of self-driving vehicles.

Much of Vibracoustic's work is focused on further improving the isolation within the cabin and minimise the effects of unwanted noise and vibrations from electric, hybrid and internal combustion engine (ICE) systems.

“Autonomy will completely change the way consumers use vehicles, freeing up the driver for a range of other activities such as reading, working, watching a movie or maybe even sleeping,” explained Dr. Jörg Böcking, CTO at Vibracoustic. “However, once the driver becomes a passenger without the need to control the vehicle or focus on the road, their perception of noise, vibration and harshness are significantly enhanced. It is important to understand that these vehicles will only be accepted if the passengers feel comfortable and safe during the journey - an area in which vibration control makes a decisive contribution.”

The two main causes of NVH issues are excitations from the road surface and from the vehicle's drivetrain and auxiliaries. For these internal excitations, Vibracoustic has a range of advanced mounts and bushings that mitigate vibrations transmitted through the axles and body to the seats and steering system. By minimising the effect of these inputs and isolating vibrations from the passengers, their comfort is increased significantly. From conventional rubber bushings to complex, hydraulic, switchable or even active mounting solutions, Vibracoustic offers one of the broadest product portfolios in the industry.

For excitations coming from the road, Vibracoustic's switchable air springs are perfectly suitable for the transition to autonomous vehicles. These digitally controlled units continuously monitor loads to keep the vehicle level. They can provide different degrees of stiffness, allowing quick transition between a firm chassis for a confident and safe driving behavior, and a more comfortable setup for long motorway trips. This technology is ideally suited to the transition from semi-autonomous to fully autonomous light vehicles, enabling the best of both worlds. As the driver switches their attention away from actively driving the vehicle, the air springs adjust from a driver-focused setting to one that is more relaxed and comfortable, providing an improved passenger experience.

Another complex issue facing vehicle manufacturers is motion sickness. Studies show that motion sickness is caused by a sustained conflict between vestibular and visual sensory inputs. It may be further intensified by the inability to anticipate the direction of motion, especially when the subject has a lack of control over the motion. Studies from other forms of transport, like rail or aviation, cannot be extrapolated to autonomous vehicles as it is a substantially different form of motion. Therefore, watching a film or reading a book during a car journey can quickly cause or compound a sense of nausea.

It is highly likely that passengers of autonomous vehicles will want to enjoy a variety of screen-based entertainment, including films and video games, on their journeys. Understanding these challenges, Vibracoustic has already developed seat dampers that are able to minimise the vibration of screens positioned on the rear of vehicle seats. These tuned mass dampers are adapted to the given package space inside the seat and eliminate perceivable vibration. Using silicon rubber and a custom fit, they provide a cost-effective solution that is 100% recyclable.

“Vibracoustic is dedicated to anticipating and solving the NVH challenges of tomorrow,” added Böcking. “Whether it's as a partner early in the development cycle or supplying class leading NVH products, we are well positioned to help our automotive customers through this significant transition. The mobility industry is now moving at an incredible pace, with numerous novel technologies implemented in each development cycle. While it may still be some time until we witness the widespread adoption of autonomous vehicles, our engineers are already working with vehicle manufacturers to solve the NVH challenges of tomorrow.”