POWER ELECTRONICS
LIDAR highway perception T
he advent of autonomous travel will have far-reaching effects on nearly all aspects of modern transport. From
cars to trucks, planes to boats, both long established OEMs and new start- ups are competing to create the perfect autonomous solution. This push has given rise to a range of technologies created to facilitate driving autonomy, with OEMs experimenting with different combinations to move up the five levels of autonomous driving.
THE PATH TO FULL AUTONOMY In an effort to categorise developments in autonomous driving, the Society of Automotive Engineers developed a five-level scale outlining driver input. Level zero is no automation, with the driver in complete control of the vehicle. Level one features basic driver assistance such as cruise control. Level two is occasional self driving, with the vehicle able to change speed and lane in certain environments such as motorways. Level three is occasional self driving where the vehicle is in full control monitoring both road and traffic. Level four is full self driving,
with the vehicle in control on an entire trip. And finally, the holy grail, level five is where there is no driver in the vehicle at all. To date, the best autonomous
vehicles are at the level two mark, with some OEMs touching into level three, such as Tesla with its Autopilot feature. Predictions as to when we’ll see true level four and five autonomy vary wildly. Ford’s former CEO Mark Fields predicted in 2017 it would have level four cars on the road by 2021; BMW and Daimler claim it’ll be 2024. Regardless of when it happens, the OEMs are all using various combinations of the same technology to get them there.
MATURING TECHNOLOGY Autonomous vehicles depend on one or more of a myriad of technologies to visualise the world around them: light detection and ranging (LIDAR), radar, GPS, ultrasonic sensors and cameras are all leveraged to one degree or another by competing companies to achieve autonomy. LIDAR is frequently the go-to for early autonomous start- ups, and is maturing quickly. Based
around a narrow infrared laser shooting short pulses at an extreme rate, LIDAR measures the return speed of each pulse to give the vehicle a sense of depth when determining what objects are in it’s view. Laser stability is achieved not by turning itself off and on, but instead by using a Mach-Zehnder modulator to interrupt one of two channels of light, effectively cancelling out the amplitude of the optical wave to create the pulses cast forward. Anyone familiar with early autonomous vehicle prototypes will know how to identify them by the small dome LIDAR units mounted on the vehicle’s roof. These domes host a spinning LIDAR array measuring and drawing the environment around them. Next-generation LIDAR systems are now doing away with roof mounted domes, instead opting for groups of integrated photonic lasers reduced in size and mounted in the vehicle’s headlights. These arrays will allow steerable beams, further increasing the resolution of the imaging platform. Many of the largest OEMs are
pushing LIDAR, such as Volvo partnering with US tech company Luminar; Audi with Bosch and Ford developing its own in-house system.
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