Developing a vehicle that can drive itself takes a lot more than just some complex artificial intelligence, state of the art graphics chips and expensive sensors. At least it does if you want the vehicle to drive itself around safely and reliably in all sorts of conditions. Just as we mere humans need to be able to see through the windows in order to navigate our environment, cameras, radar and lidar need an unobstructed view of the world.
It’s been a couple of years since Waymo first published a short video clip showing a washer system for its rooftop sensor dome and other serious players in the automated driving space have also been developing their own solutions. When GM and Cruise first demonstrated their automated vehicles in late 2017, the sensors were equipped with washers. Now Ford’s third-generation sensor system also includes some unique solutions.
Driving in the real world exposes a vehicle to all manner of debris from winter salt spray to bird droppings to splattered insects. I arrived home from a recent road trip to find the front mounted radar sensor on a Mazda CX-5 caked in bugs. While the bugs didn’t impact the performance of the radar, they would affect cameras and lidar.
To address this, Venky Krishnan, Ford Autonomous Vehicle Systems Core Supervisor and his team consulted with zoologist Mark Hostetler to learn more about bugs. They crafted a bug launcher to fire dead insects at sensors and record it with high-speed cameras. If you’ve ever driven in areas with a lot of insects, you’ll know that simply using a conventional windshield washer system and wiper is simply not up to the task of removing a bug that strikes the glass at 70 mph.
Back in the 1980s when I was driving a compact pickup truck to college and back, I had a bug deflector on the leading edge of the hood that did a surprisingly good job of reducing the impacts on the glass. This was essentially an air dam that deflected the air flow up and over the cab, taking many of the bugs with it.
In recent years, most vehicles, including those from Ford have adopted a similar airflow management principle to reduce aerodynamic drag. Vertical slots in the front fascia channel air through the front corners and out a slot just ahead of the front wheels. The air coming out of these long, slim vertical slots essentially creates an air curtain that acts like a shroud over the wheel, limiting the turbulent air flow from the rotating wheels.
Krishnan and his team incorporated something like this in to the structure that holds the sensors on the roof of the automated vehicles (AVs) being tested by Ford and Argo AI. Air is channeled from the front of the so-called “tiara” and across in front of each camera. This curtain of high speed air prevents most of the bugs from impacting the sensor. Still, those air curtains aren’t impermeable.
When debris does hit the sensor, software in the AV system can detect if it has become obscured. More advanced washer nozzles with higher pressure and reduced fluid use can spray down the affected sensors to get them clean and then a quick blast of air blows them dry. This system is used for both the cameras and lidar.
Other companies are also working on a variety of solutions to address the challenge of maintaining visibility for the sensors on automated vehicles. Hitachi has developed a high-pressure aerosolized sprayer that can clean the sensors with only one-tenth of the fluid used by current sensors. Startup Seeva Technologies has developed a fluid heating system that they claim makes the washer fluid more effective at removing debris from the sensors.
Notably, the one company that persistently claims it will make its cars capable of level 5 automated driving with just software updates doesn’t feature any of these solutions. Only the forward looking cameras behind the windshield of Tesla vehicles have any means to be cleaned and they rely on old fashioned windshield wipers and washers which are much less effective.
Cleaning sensors may sound like a mundane engineering task, but it is a crucial one if the massive investments being made in the self-driving technology are ever really going to pay off. If a car is disabled by getting sprayed with road salt or driving through a cluster of mayflies, it won’t be of much value to anyone.
This article was originally sourced from here.