Autonomous vehicles are becoming a common sight in many industries and in consumer the world. From self-driving cars to automated guided vehicles to autonomous robots and machines, this technology is already proving it has tremendous value. However, with so much research and improvement needed for true widescale deployment, the future of this technology is still unclear.
One of the biggest concerns surrounding this technologyis its safety and reliability. Tony Zarola, general manager ofAnalog Devices (ADI) offers insight into what the futureholds for autonomous vehicles and how sensors—specifically inertial measurement units—may play the biggest rolein ensuring self-driving success.
THE ROLE OF AN IMU IN AUTONOMOUS VEHICLES
Several modalities need to work in near-perfect syn-chrony to enable fully functional, fully autonomous machines. Among these modalities, perception technologysuch as radar, lidar, and cameras receive much of the creditfor advancing the autonomous movement. However, theunsung hero, but critical lynchpin to an autonomous operation that these modalities hinge on—both in terms ofimage stabilization and vehicle navigation—is the inertialmeasurement unit or IMU.
IMUs are based on multi-axis combinations of precision
gyroscopes, accelerometers, and in some cases magnetome-
ters. This plug and play technology reliably senses and pro-
cesses multiple degrees of freedom, even in highly complex
applications and under dynamic conditions, providing a con-
sistent signal when other modalities are compromised. IMUs
feature full factory calibration, embedded compensation,
sensor processing, and a simple programmable interface.
Let’s step back from full autonomy for a second and talk
about something more immediate in terms of market pull.
If you consider advancing autopilot, also known as hands-
off driving, you may be surprised to learn that the critical
specification is system latency. While it takes an IMU mere
microseconds to update and
output a relative measure of
location, cameras, lidar, and
radar take milliseconds—a
lifetime when you consider
highway speeds. Combined
with environmental noise
that causes perception blind
spot, as the update rate
continues to get longer, the
fusion engine experiences
information lags and gaps.
It is during these critical
“flying blind” moments
that the machine receives
and relies on the speedier
data supplied by the IMU.
Beyond that, IMUs are the
only sensing mechanism
not affected and potential-
ly rendered useless, by ex-
ternal conditions. Adverse
weather conditions, excess
heat or cold, wavelength restrictions, glare, and many oth-
er external factors can impede the reliability and function-
ing of other sensing modalities, making IMUs essential for
situations when those situations arise.
CHALLENGES IN THE INDUSTRY
Autonomous vehicles are an exciting extension of autonomous machines. However, while we’ve all been enamored bythe concept, potential implications, and benefits of a driverless future, truly autonomous, personally owned cars are notyet technically or financially viable. Autonomous vehicles willimpact the safety and lives of millions of people who use ourroads on any given day, and there are vast, nuanced challenges that need to be overcome before the underlying technologycan be introduced in non-controlled environments.
Although it is common to see vehicles that operate in
a limited speed constrained autopilot mode and/or can
self-park, the challenge ahead of us is to add speed with-
out losing safety to get these semi-autonomous vehicles on
roadways without relying on an alert driver. New technol-
ogies, including high-performance IMUs, will help expand
the speed envelope. There are many other hurdles to over-
come, considering the system will have to account for an
unconstrained environment and mapping the entire world–
including every lamppost, streetlight, and stop sign, not to
mention accounting for pedestrians and unpredictable en-
counters with wildlife–is a gargantuan task.
Original equipment manufacturers are faced with two options. They can advance existing technologies such as automatic emergency braking, valet parking, and autopilot, or invest in future technologies that seek to move the needle fastertoward fully autonomous driving. However, ultimately, theyneed people to buy their vehicles, and considerable investments in technologies that make cars too expensive for the average consumer could result in a diminished or negative ROI.
WHAT THE FUTURE WILL LOOK LIKE FOR IMUS IN
Each sensing modality has its strengths and weaknesses,but by leveraging sensor fusion techniques, the strengths cancomplement one another, and the weaknesses can be supported. Cameras can get dirty and are susceptible to glare.Radar can be unable to pick up smaller objects or project avery clear image. Lidar is expensive and offers only limitedusage in adverse weather conditions. And as noted earlier,all these modalities update more slowly than IMUs, withthe time lag potentially creating a dangerous situation foroccupants of the car and others on the road. These machinesneed trusted sensors and architectures, along with fail-safeback-up systems. In this endeavor, high-performanceIMUs can take on the role of vehicle arbitrator to assist inguiding the vehicle when other sensing modalities fail.
The reason that IMUs work when all other modalities failis their robustness to environmental impact. Beyond beingunaffected by changes in temperature, IMUs, such as thosefrom Analog Devices, feature vibration rejection, enablingthe elimination of noise (such as vibrations generated bydriving on rough roads) from the signal. Without this feature, vibrations from a moving vehicle would come throughas a signal and affect the coordinates and direction, andtherefore the safety of the car. This ability to reject conditions means the output of the sensor is uncompromised.Yes, a drawback of IMUs is the drift that is inherent in allgyroscopes, but with the right IMU that offers a greaterdegree of environment immunity, engineers can predicterror growth, and incorporate that change into the algorithm to maintain the reliability of the IMU.
Ultimately, the future of autonomy comes down to reliability. What modalities will navigate this autonomousvehicle, drone or robot as quickly, safely, and efficientlyas possible? What will be reliable when a split-second decision could be the difference between life and seriousinjury (or even death)?
For more, visit newequipment.com/21129236
By Tony Zarola
An inertial measurement unit is the only sensing mechanism that is not affected or potentially rendered useless by externalconditions, making them an essential technology for autonomous vehicles.
IMUs: The Lynchpin to theFuture of Autonomous Vehicles
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