Poised and prepared: proactive sensor cleaning is a must

For automated vehicles, connectivity could mean the end of mucky sensors. By Freddie Holmes

While some sensors are sheltered from the elements by the windscreen, others sit around the ‘belt line’ of the car. While this may be the ideal viewing point for vision sensors, it is also the dirtiest. Research from fluid management and sensor cleaning specialist dlhBOWLES has found that even in normal road conditions, camera sensors located around the belt line can be almost fully obscured within just 15 minutes of driving.

The importance of ensuring that those sensors are clean when the car sets off is clear. However, they must also stay clean whilst in transit. Maryland-based dlhBOWLES believes its sensor cleaning technology can be paired with a range of connected services to help vehicles ‘prep’ certain sensors depending on what is coming up ahead.

The idea is to help avoid a scenario where a sensor is obscured when it is required to navigate a turn or another manoeuvre. What’s more, if there is no human driver available to apply some elbow grease, such vehicles run the risk of being incapacitated mid-way through a drive—or worse. “Sensor availability is vital to autonomous vehicles (AVs),” says Russell Hester, Director of Business Development at dlhBOWLES. “Many of us take for granted that when we open our eyes or look in a new direction we can see; imagine the concern if every time you looked to your left, you were blind.”

While this may seem dramatic, the reality is that AVs rely on their sensors to operate—if they are blocked, the car cannot see. “If sensors are obscured or otherwise not fully functional when needed, an AV will need to take countermeasures to keep their passengers safe,” Hester explained. In such a case, he suggests, the vehicle could cautiously pull over to the side of the road—“like when we slowly fumble around in the dark with our hands”—but this is far from ideal. There must be a better solution, or preferably, a preventative measure.

Even in normal road conditions, camera sensors located around the belt line can be almost fully obscured within just 15 minutes of driving

The technology at hand is fairly straightforward and is borne out of the company’s decades of experience in windshield washers. To keep sensors clean, one of the most effective ways is to spray a special mix of fluid to remove that muck.

Sensors can become blocked surprisingly quickly, and even in seemingly clear conditions. And it’s not just mud and road dust to consider; in the snow and muck of a harsh Michigan winter, things are even worse. “Under normal autumn or winter conditions in the USA it is not uncommon for sensors to become dirtied to a point of ineffectiveness in as few as ten miles,” said Hester. “While our data from test vehicles in Michigan or Ohio—known for bad winter road conditions— was not surprising, this corroborating result in the Southern state of Maryland was unexpected.”

While the problem is certainly more pronounced for driverless vehicles in future, the challenge is also relevant to cars on the road today. Advanced driver assistance systems (ADAS) are no longer reserved for upmarket marques; features such as automatic emergency braking (AEB) and lane-keep assist (LKA) are commonplace even on entry-level vehicles, and many rely only on a forward-facing camera sensor. If that becomes blocked, the driver can be met by a barrage of warnings—in some cases advising that he or she pull over and sort things out.

Hester has concerns that this could hamper the industry’s effort to make automated functions more attractive to prospective buyers. “Present ADAS features are mostly related to convenience functions like cruise control and can be substituted by manual driving,” he said. “Having these features unavailable on a vehicle becomes a nuisance for the owner. As ADAS features evolve into more and more safety-critical functions then there should be a concern of sensor availability.”

By extension, that would likely make robotaxis more of a hard sell in future. “Intermittent availability of ADAS features on today’s vehicles do present a risk to the adoption of AVs,” he continued. “Reliability and comfort with the use and operation of today’s ADAS functions, their related hardware and dependability, is establishing a foundation of trust in the technology whether we like it or not. Any apprehension the common driver may experience in their vehicle today will influence their faith in tomorrow’s AV.”

If sensors are obscured or otherwise not fully functional when needed, an AV will need to take countermeasures to keep their passengers safe

Mission-critical

There are a variety of instances where sensor availability comes into play. Sensors could clean themselves whilst parked ‘valet style’, for example. However, this would require predetermined spots to be set up. Self-cleaning sensors could make a mess of a home garage, but outdoor areas with appropriate drainage would reduce the environmental impact of any cleaning products.

Even reversing cameras require a once-over before setting off, advised Hester. “It is best to clean the camera when you pull in to your parking spot at work at the beginning of the work day—before the vehicle’s next ‘mission’. Waiting until the end of the work day when the driver is about to back out of the parking spot reveals that the soiling from the morning’s commute has dried on the lens, rendering the camera useless and unsafe. This forces the driver to rely on traditional visual checks,” he warned.

Critical driving functions that rely on a clear view of the road may require the introduction of connectivity. If a driverless vehicle’s GPS system knows that the vehicle will soon take a right-hand turn, it can perform a system check to ensure the necessary sensors are good to go. “Sensor availability can be validated in time for a safe execution of that right-hand turn,” explained Hester. “If a required sensor is determined to be dirty, the vehicle can perform a pre-emptive clean.”

Any apprehension the common driver may experience in their vehicle today will influence their faith in tomorrow’s AV

Join the conversation

Sensor availability is one of many niche elements to vehicle automation that the industry will need to consider. Ensuring that sensors are poised and prepared for every eventuality will help to eliminate any consumer frustration when using driver-assist features today. It will also be vital when those sensors become the vehicle’s primary means of navigating complex road situations safely.

While the topic may appear to have been overlooked, Hester advised that it is a major talking point behind closed doors. “Many of our customers and technology partners in the industry are actively exploring this matter,” he concluded. “As every month passes more simulations are being run, hardware and software is being tweaked and on-road miles are accumulated. A number of automakers are implementing sensor cleaning systems on current ADAS features.”

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