We recently looked at an AAA study that linked the performance of lane-keeping assistance and automatic emergency braking systems and found that these ADAS systems can be influenced by environmental conditions such as rainfall and dirt. But there is new technology from the digital camera world that seems promising: ultrasonic cleaning. ADAS sensors perform their best when they are kept clean, but it can be a challenge to ask owners to wipe down the sensors periodically. Heck, it is a challenge to ask some people to keep their cars clean in general. However, the British engineering firm TTP is looking at the new ultrasonic technology for automotive sensors. In the meantime, it isn’t too much to ask to keep your vehicle reasonably clean so ADAS systems can do their job with the most effectiveness.
How Ultrasonic Cleaning Works
Tom Jellicoe, head of autonomous technology at TTP, notes, “We are looking at ultrasonic cleaning as a complementary technology that could be directly integrated into the sensors and provide thorough cleaning when they inevitably get dirty. This is not a new idea. Ultrasonic baths are a staple fixture in labs and workshops for cleaning the surfaces of everything from silicon wafers to engineering components. The idea has even been proven out for cleaning sensors. Since 2003, digital cameras have used ultrasonic components to remove dust and dirt from their internal parts.”
Imagine if the entire vehicle could use ultrasonic cleaning to prolong visits between car washes … but the cost of the technology makes it viable only for sensors.
According to Jellicoe, ultrasonic actuation of a surface prevents weakly bound dust and dirt from sticking through atomization. This process is the most effective mechanism for removing unwanted material from the surface. Jellicoe said, “It is where the surface accelerates fast enough to break the surface tension of the wetting layer on the surface and form a droplet, which is ejected along with anything that may be suspended if dissolved in the wetting layer. This effect is also exploited in some room-fragrance dispensers, which atomize oils containing pleasant aromas” — except instead of releasing perfume, the technology expels dirt.
“We’ve looked at two potential cases: a small circular piece of glass similar to the front face of a camera and a rectangular piece of rigid polymer similar to the sort of covers many companies are mounting on the front of their lidar sensors,” Jellicoe said. “In both cases, it is possible to get to the atomization threshold by driving the actuator just about as hard as the humble doorbell buzzer or parking sensor. This is a really encouraging result from the point of view of robustness and power consumption. These results are based on a relatively simple model, and a number of additional challenges need to be addressed to integrate this successfully into sensors, but this certainly shows there is significant potential there.”
Organizations like the Vision Zero Automotive Network are for the promotion of these new cleaning technologies and how they can be integrated into vehicles that are on the road today.
Improving Performance and Ultimately Safety
Eventually, we see these technologies moving toward the aftermarket to help keep sensors running at peak performance in poor environmental conditions. Even the most meticulous person with a rigorous car-cleaning regimen can still encounter the splash of muddy water from a truck going in the opposite direction. The sensors available today will still work in these conditions, but the performance may be diminished. We value new ways of making sensors foolproof so end users can be confident they are working at their best. With more studies and research, we hope to see a decrease in accidents. As we move closer to autonomous vehicles, we are also moving toward a world of sensors. Keeping them at peak performance will ultimately help our goal and that of Vision: to have “Zero” deaths attributed to preventable motor vehicle accidents.