Advanced vehicles progressively rely on advanced driver assistance systems (ADAS) to facilitate easier, safer, and more efficient driving.
ADAS differ in scope from basic “hands-on” features such as cruise control to hi-tech systems that can automate emergency braking, lane-changing, and parking tasks.
At the maximum level, ADAS empowers vehicles to become fully autonomous by employing various processors, sensors, and actuators that handle all driving-related tasks cooperatively.
The accelerating execution of ADAS in new vehicles means that vehicle design is shifting in extreme ways. Mechanical power steering units, for instance, are being replaced by fully electronic “steer by wire” control units, while the positioning of LiDAR sensors and cameras all over vehicles is becoming a common feature.
As vehicles become progressively reliant on unconventional technologies, vehicle manufacturers must find ways to guarantee their functional safety. This article will cover the latest trends in ADAS before analyzing the challenges of executing two key ADAS technologies: LiDAR and steer-by-wire.
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Levels of Vehicle Automation
The Society of Automotive Engineers (SAE) describes vehicle automation levels on a scale from 0 to 5.1
SAE level 0 refers to a vehicle without any automation. This is a vehicle wherein monitoring the environment, acceleration, and deceleration are constantly reliant on a human driver. However, it may be aided by provisional “active safety systems” such as automatic emergency braking, or lane-departure warnings.
SAE level 1 refers to vehicles that provide either steering or braking/acceleration assistance to the driver—for instance, adaptive cruise control or lane centering—while SAE level 2 vehicles offer both, allowing a “hands off” experience under certain circumstances—though the user must constantly observe the environment.
SAE level 3 refers to “eyes off” automation, where the vehicle can manage all fundamentals of driving, including checking the driving environment. However, a human driver should be ready to take control of the vehicle when requested.
SAE level 4 refers to (“mind off”) automation, where the vehicle can safely pull over in case the driver fails to react to an appeal to intervene.
SAE level 5 (“steering wheel optional”) describes a vehicle that drives autonomously and never needs human involvement. Such a vehicle can carry out autonomous self-driving under all road environments, anywhere in the world, and under any weather circumstances.
The autonomous vehicle market is growing fast. Worth approximately $94.4 billion in 2021, experts believe the market will grow further at a rate of more than 30% year-on-year until 2030.2,3
Vehicle manufacturers are contending to receive a share of this rapidly developing market. Tesla cars, for instance, are fitted with hardware that Tesla claims will allow 100% self-driving in the future, with beta versions of their self-driving software currently matching level 2 automation.
In the meantime, manufacturers, including Mercedes, BMW, and Hyundai, are creating SAE level 3 vehicles scheduled to be launched in the next few years.4–6 Toyota and Honda are already testing and trialing level 4 vehicles.7,8
Being aware of the driving environment is crucial to driving automation systems. LiDAR—an acronym for light detection and ranging—is one of the core technologies used to achieve that.
LiDAR functions similarly to RADAR (radio detection and ranging). Both technologies can assess distances by producing a pulse of electromagnetic radiation and recording the time taken for the pulse to reflect.
However, LiDAR provides an important performance benefit in automated vehicles compared to RADAR as it employs lasers instead of radio waves. This allows LiDAR systems to develop a 3D map of their surroundings with greater resolution than RADAR systems.9
Car manufacturers, including Mercedes-Benz, Volvo, and BMW, have stated plans to add LiDAR sensors in future models of their cars, with Volvo mentioning that the system will allow their cars to decrease accidents by 9%.10
LiDAR devices are multifaceted and sensitive. If LiDAR sealing becomes faulty due to vandalism, a small collision, stone chipping, or natural deterioration, water and water vapor can begin to penetrate the enclosure. Water ingress not only harms optical performance but, over time, results in the hazard of corrosion of the electronics.
Transitioning from traditional power-steering systems to steer-by-wire systems is one of the most important alterations to vehicle design.
Power steering systems use electrical or hydraulic actuators to help drivers to turn the vehicle’s wheels using the steering wheel. Importantly, power steering systems are failsafe. They integrate a full mechanical connection between the driver and the car's wheels, guaranteeing that the driver can still navigate the car if the power steering system falters.
Steer-by-wire systems are considerably different. To enable automated steering, vehicle manufacturers are progressively choosing to substitute mechanical linkages between the steering wheel and wheels with totally electronic ones.
In a car that employs steer-by-wire, turning the wheel no longer permits the car's direction to be altered: rather, the steering wheel acts as an electronic controller whose input can be followed, altered, or ignored completely. This is subject to the car’s automation level and driving activity.
The crucial goal of steer-by-wire systems is to enhance safety and driver experience by allowing the car to take control of steering functions. However, as with LiDAR, doing so is based on vehicle manufacturers being able to guarantee the dependability and functional safety of steer-by-wire systems in all driving scenarios.
The substitution of strong mechanical linkages with sensitive electronic ones emphasizes the significance of checking water ingress in automated vehicles. Here, the problem is more with water level than humidity, but the hazards are no less critical. Water ingress into the electronics can cause corrosion and produce unexpected malfunctions.
Regulations for Automated Vehicles
For vehicles to reach SAE levels 4 and 5, ADAS, such as steer-by-wire systems and LiDAR, must be reliable and guarded by failsafe mechanisms. The condition of these systems must be tightly monitored to provide early discovery of deterioration, preventing serious errors.
The United Nations Economic Commission for Europe (UNECE) is now involved in a legal framework to guarantee that autonomous cars stick to a high level of safety.11
The two key protocols for automated steering and lane-keeping systems—UNECE 79 and UNECE 157, respectively—compel the manufacturer to state how the system will not fail if there is an issue of water ingress or other problems.12,13
The only step manufacturers can take to ensure that such systems stay safely guarded against water ingress is to deploy sensors that can detect it before it can cause an error. Moisture sensors offer a cost-effective way of tracking ADAS, including LiDAR sensors and steer-by-wire systems, installing a noticeable humidity increase as a proxy for water ingress.
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Sensors from Sensirion AG Switzerland
Sensirion has been creating automotive sensors for more than 20 years. Currently, Sensirion’s sensors are used in numerous new cars.
The SHT4xA sensor from Sensirion is an ultra-compact, digital humidity, and temperature sensor. It is designed particularly for sensing moisture in important automotive applications. The SHT4xA can measure relative humidity with a precision of ±2% and temperature at ±0.3 °C. It accomplishes the challenging reliability necessities for use in automated vehicles.
Built for 85 °C/85%RH reliability testing, it stays operational in condensing surroundings and features an in-built variable-power heater for cutting-edge onboard diagnostics. Its forthcoming ASIL grade A specification allows direct incorporation into any functional safety-applicable design.
The sensor is ideal for SMT assembly, where its wettable flanks package guarantees automatic optical inspection (AOI) of the assembled printed circuit board (PCB). On the same hardware system, Sensirion is designing a true water sensor, providing a safety-switch-style tracking of water ingress into important electronics.
Overall, the SHT4xA is designed keeping in mind ADAS integration, making it the suitable choice for checking water ingress and humidity exposure in LiDAR and steer-by-wire platforms.
References and Further Reading
- J3016_202104: Taxonomy and Definitions for Terms Related to Driving Automation Systems for On-Road Motor Vehicles - SAE International. https://www.sae.org/standards/content/j3016_202104/.
- Insights, F. B. Autonomous Car Market Size to Grow Worth USD 11.03 Billion at a CAGR of 31.3% for 2021-2029 | Fortune Business Insights. GlobeNewswire News Room https://www.globenewswire.com/en/news-release/2022/06/08/2458427/0/en/Autonomous-Car-Market-Size-to-Grow-Worth-USD-11-03-Billion-at-a-CAGR-of-31-3-for-2021-2029-Fortune-Business-Insights.html (2022).
- Autonomous Vehicle Market Size, Share, Trends, Report 2022-2030. https://www.precedenceresearch.com/autonomous-vehicle-market.
- BMW 7 Series To Reach Level 3 Autonomy Next Year - Forbes Wheels. https://www.forbes.com/wheels/features/bmw-7-series-level-3-autonomy/.
- Weintraub, S. Mercedes DRIVE PILOT: Level 3 luxury, coming soon to US. Electrek https://electrek.co/2022/07/22/mercedes-drive-pilot-review/ (2022).
- Korean firms enhance car cybersecurity before Level 3 autonomous car releases - 매일경제 영문뉴스 펄스(Pulse). https://pulsenews.co.kr/view.php?year=2022&no=147214.
- Honda Is Beating Tesla In Driverless Car Race | CarBuzz. https://carbuzz.com/news/honda-is-beating-tesla-in-driverless-car-race.
- CORPORATION, T. M. Toyota to Offer Rides in SAE Level-4 Automated Vehicles on Public Roads in Japan Next Summer | Corporate | Global Newsroom. Toyota Motor Corporation Official Global Website https://global.toyota/en/newsroom/corporate/30344967.html.
- Automotive, I. The Ultimate Sensor Battle: Lidar vs Radar. Medium https://medium.com/@intellias/the-ultimate-sensor-battle-lidar-vs-radar-2ee0fb9de5da (2018).
- Volvo plans to install laser sensors on all new cars to increase safety. Financial Times (2022).
- Framework Document for Automated/Autonomous Vehicles (UPDATED) | UNECE. https://unece.org/transport/publications/framework-document-automatedautonomous-vehicles-updated.
- UN Regulation No. 157 - Automated Lane Keeping Systems (ALKS) | UNECE. https://unece.org/transport/documents/2021/03/standards/un-regulation-no-157-automated-lane-keeping-systems-alks.
- UN Regulation No. 79 - Rev.4 - Amend.3 | UNECE. https://unece.org/transport/documents/2021/02/standards/un-regulation-no-79-rev4-amend3.
This information has been sourced, reviewed and adapted from materials provided by Sensirion Inc.
For more information on this source, please visit Sensirion AG.