New MEMS Sensors Driving AV Innovation
Image Source:
posteriori/shutterstock.com
By Adam Kimmel for Mouser Electronics
Published March 5, 2020
Introduction
Recent shifts in consumer preference for renewable and sustainable energy has led original equipment
manufacturers (OEMs) back to the design rooms to develop a solution: Commercially viable electric vehicles
(EVs).
Meanwhile, engineers and software developers continue to raise the bar for connected devices. It was this
confluence between vehicular electrification and integrated technology that led automakers to an exciting
conclusion: A fully autonomous vehicle (AV) is possible.
Of course, AVs do not always dictate an electric drivetrain; yet, several synergies create a logical pairing.
Both technologies have the same early-adoption-minded consumer and address environmental concerns. Feature
integration is more straightforward in the simpler electric drivetrain. Finally, passive-control system
optimization during operation addresses one of the most significant limitations of current EVs: range.
Although the case for electric, autonomous vehicles is clear, the state of the art has not yet reached the
tipping point of mass adoption for two reasons:
- The cost of EVs is still too high, even without the autonomous features
- The self-driving performance is not reliable enough for full (level 5) autonomy.
Vehicles need a reliable way to map their surroundings and to transfer large amounts of data to the CPU. The
answer to this challenge is MEMS sensors. These sensors will enable widescale commercialization of AVs now and
will sustain them with new applications in the future. This article describes the principal functions that MEMS
sensors play in autonomous vehicles: LiDar beam steering, battery health monitoring, vehicle reliability, and
passenger connectivity.
LiDAR Beam Steering and Battery Health Monitoring
LiDAR has long been the industry standard for autonomous surrounding-mapping. In prototypes, engineers mount the
LiDAR sensor on the roof of the vehicle, and it continuously scans to create a map of the area surrounding the
car. The central computer uses artificial intelligence (AI) to analyze the data rapidly, and then it feeds
commands to the vehicle systems for how it should react (Figure 1).
The increased market focus around AVs has uncovered fundamental challenges in AVs, however. Like a satellite
dish, adverse weather conditions such as fog and heavy rain inhibit the accuracy of the imaging. Reduced imaging
accuracy increases the risk of an undesired vehicle response. MEMS sensors function in all weather conditions.
Also, they mitigate false responses because of road vibration. As a result, MEMS sensors enable LiDAR Beam
steering, a motionless approach to scanning the area around the vehicle. This approach mitigates many challenges
of the abrasive automotive environment. MEMS-enabled beam-steering provides a high likelihood of success in
image mapping.
Figure 1: AV sensors scan the road, analyze data and command reactions from
the vehicle. (Source: Andrey Suslov/shutterstock.com)
Although industry development is addressing some of the challenges with LiDAR, the technology that achieves level
5 autonomy will likely need to incorporate redundant images maps to address all conditions, such as a
combination of thermal imaging, light, and sound waves. These can be rapidly analyzed against each other to
verify the signal sent to the CPU. As these technologies proliferate through the market, MEMS will be less
crucial to the mapping function.
Another application of MEMS sensors for EV operation is in battery-health monitoring. This function will be
crucial as the industry pushes EVs for 500-plus kilometer range. Analogous to how MEMS sensors process
information on the vehicle's surroundings, they transmit data about the battery’s performance to the CPU. This
information can adjust the vehicle's operation to maximize battery life.
Reliability
The shift from “drivers” of cars to "users" of AVs is not a complete pivot from traditional automotive
technology. The disruptive innovations enabled by the autonomous movement cause consumers to re-think how they
travel. Despite that new mindset, passengers still expect the reliability to which they have become so
accustomed. Many of these features impact the vehicle's sensors.
Cold start is an especially big hurdle for EVs. ICEs convert chemical energy to thermal energy through the
combustion reaction, then convert the thermal energy to electrical. Although the double energy conversion is a
drawback for fuel economy, the intermediate thermal energy step provides an ample supply of high-quality energy
for the engine to warm components. OEMS have tried several solutions to heat EVs. These approaches include
Peltier elements, heat pumps, and electric heaters.
The challenge with a cold start for the engine also impacts sensors. Automotive applications provide aggressive
conditions for sensors, and MEMS are robust enough to overcome them. MEMS aid in cold startup to below -50°C
(below the freezing point of traditional engine coolant), and can also withstand environments up to 125°C.
MEMS sensors also do not exhibit activity dips and offer low radio-frequency (RF) noise. These benefits offer
consistent performance in all conditions, something crucial for AV safety. Safety and technology consistency are
also crucial to consumer acceptance of EVs. MEMS sensors are flexible in programmability, and engineers can
customize the operating range for specific applications. They operate within a frequency range between 1MHz to
725MHz, to serve functions that operate within that range.
Passenger Connectivity
The most significant difference in the user experience of AVs is connectivity. Drivers are less willing to
disconnect for road trips, heightening the anticipation of EV/AV arrival. A critical challenge of AVs is the
instantaneous data processing the vehicle must do. This analysis occurs both within the vehicle (automotive
Ethernet) and with the outside. Although MEMS sensors' consistent performance and low RF noise improve safety
and reliability, they also improve the infotainment experience. The sensors allow the vehicle to simultaneously
process massive amounts of data to assess the driving conditions, monitor the critical vehicle features, and
consistently entertain the passengers (Figure 2).
Figure 2: MEMS sensors are improving not only internal vehicle workings, but
also user experience, processing data, and providing entertainment. (Source: sdecoret/shutterstock.com)
Because sensors are small, they do not add as much to vehicle mass as other sensor types. This spatial efficiency
improves range and frees up space in the vehicle. The rapid processing time that MEMS sensors provide matches up
well with 5G, which requires tight timing to communicate with the environment and conditions external to the
car.
Market Information
The EV/AV market is booming and is showing no signs of slowing. IHS Markit projects EVs will comprise 50 percent
of the automotive market by 2030. Analysts project future applications for MEMS sensors in rapid charge
innovation, passive battery thermal management, and improved spatial sensing. AV presents the opportunity for
groundbreaking innovation within the sensor market. But for AVs to reach level 5 autonomy, engineers, and
developers are still a few major innovations away from mass adoption.
Conclusion
MEMS sensors are critical to AVs. They offer superior performance, reliability, and application utility, and
enable development of the features that will enable the mass commercialization of AVs. Once the sensor
technology integrates with 5G and improves beam steering to unlock level 5 autonomy, AVs can finally take the
users wherever they want to go.
Adam Kimmel has nearly 20 years as a
practicing
engineer, R&D manager, and engineering content writer. He creates white papers, website copy, case studies, and
blog posts in vertical markets including automotive, industrial/manufacturing, technology, and electronics. Adam
has degrees in Chemical and Mechanical Engineering and is the founder and Principal at ASK Consulting Solutions,
LLC, an engineering and technology content writing firm.
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