Today’s automotive cabin would be unrecognizable to Karl Friedrich Benz, who patented his Benz Patent Motor Car—often cited as the first motor car—in 1886.

Over the next 120 years, automotive engineers have refined every major subsystem in the car, including the controls that drivers use to perform routine functions, such as shift, drive, park, headlights and volume control. During this transition, mechanical dials and buttons have given way to active touch surfaces in the car’s center display screen.

Yet this advancement has created a new problem. Touchscreens force the driver’s eyes off the road, causing more opportunity for distracted driving as visual perception takes a higher cognitive load on human neural processing than haptics. Touchscreens with contextualized haptic feedback, however, can provide a level of confirmational haptic feedback that is similar to mechanical controls, assuring the driver that the car has received their input.

All senses are not created equal

Recent research in cognitive neuroscience supports this claim. A group of academics published “the first quantitative support for introducing digital haptics into automobile tablet interfaces” in June 2022. These researchers compared three different combinations of search scenarios to determine the impact of cognitive load on response time.

In all three scenarios, the test participant interacted with a centrally presented visual task, which emulated the car’s dashboard, as well as a secondary task of laterally presented sliders on a tablet. The sliders were either presented visually, haptically or visuo-haptically. After measuring response times, the researchers concluded that “visual search performance was fastest when participants simultaneously performed the tablet task with only haptic information available on the secondary platform.”

A second study, conducted in Sweden in 2022, tested how long it took a driver to perform four tasks—such as adjusting temperature and volume controls—while driving at 68 mph, according to the study. Performing the tasks on the 2005 Volvo V70, the only car without a touchscreen, took just 10 seconds. Executing the same tasks on the MG Marvel R required 44.9 seconds, and the Tesla Model 3 clocked the tasks at 23.5 seconds. According to the study, “the worst-performing car needed 1,400 meters to perform the same tasks for which the best-performing car only needed 300 meters.” You can see the results here.

This does not mean that touchscreens will go away. Far from it. From the look of the Mercedes-Benz CLA Class concept car, touchscreens are getting even larger.

If that is the trend in automobiles, what can automakers do to mitigate potential safety issues exacerbated by touchscreens? They can implement better haptic technologies.

Evolution in haptic technologies

Popularized in the late 1990’s, the first-generation haptic technology relied on the eccentric rotating mass vibration motor (ERM), a large actuator that is still used in many game consoles today. The ERM, however, fell short in automotive cabins because it is imprecise and not very powerful, making it ill-suited for precise haptic effects.

The second-generation haptic technology, the linear resonant motor (LRA), is an actuator that simulates the human sense of touch by producing feedback, such as a slight vibration, when drivers perform a routine function. LRAs, however, are hampered by problems of their own. Chief among these are high latency (slow start/stop times), non-localized effects, and limited frequency bandwidth (which creates a monotonal “buzz”). No one really likes a mushy monotone sensation when pressing a button on a touchscreen.

Volkswagen (VW), for example, went to market in 2022 with LRA-based haptic buttons in the steering wheels and touchscreens of some of its vehicles, including the Tiguan, GTI and the ID.2, for use in standard operational functions. Customer dissatisfaction was so high with the poor haptic feedback that by late 2023, VW announced a return to analog buttons for these standard functions.

Piezo haptics: the change-agent in tactile feedback

The third-generation haptic technology—piezo haptic semiconductor platforms—provide localized feedback that has an ultra-fast response time (enabling 25–40 effects in the same time slice that LRAs use to create a single effect) and offers a much wider frequency range. This third-generation haptic tech allows user interface designers to craft effects that are crisp and feature multiple frequencies. Designers can produce a specific “feel,” or if desired, create a feel that closely matches the feedback delivered through their traditional mechanical buttons.

Piezo-based haptics also offer the benefit of customizability, allowing automotive designers to adjust preferences and create more engaging experiences. An automaker could even develop a recognizable click sensation that is specific to their brand. In this way, the automaker could potentially enable the same level of differentiation in haptic feedback that already exists in auditory cues in the automotive environment.

Haptics beyond the touchscreen

As we now know, the automotive designer can implement piezo haptics almost anywhere in the automotive cockpit. Piezo haptics can convey different types of time-critical information to the driver to enhance driver safety. For example, piezo haptic-enabled steering wheels could alert drivers to changes in the road environment, such as slippery roads or vehicles in the car’s blind spot. Once detected, the piezo haptic system could activate the steering wheel to deliver immediate feedback through location-based vibrations. Such a rapid haptic feedback mechanism would help to prevent accidents, improving overall vehicle safety.

Piezo haptics can also enable more seamless human machine interfaces as vehicles adopt higher levels of conditional automation. For example, precise haptic cues through the steering wheel can communicate when autonomous modes are engaged.

As driving becomes increasingly assisted, haptics provides an intuitive channel for vehicles to convey critical information and cues without overloading visual or auditory senses. Integrating high-definition, multi-modal haptics into modern automotive designs enhances safety while creating a richer user experience.

The future is haptic

The full potential of haptic tech in cars is yet to be revealed. In the near future, expect to experience multi-modal haptic systems that combine various elements of touch, including kinesthetic, tactile and vibrotactile. Such systems will issue diverse vibrations, pulses, and rumbles that provide more immersive and situationally aware responses that inform drivers how to operate vehicles more safely.

Our experience with the automotive industry has shown us that innovation is never static. While the industry’s first haptic user interfaces in automotive cabins depended first on ERMs and then on LRAs, we believe that the industry will move to piezo haptic platforms as the next dominant enabling technology to transform haptic feedback in the automotive space.

By: DocMemory
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