EDITOR’S CHOICE FEATURE
RADAR, THE CAR’S VIRTUAL EYE
Donal McCarthy, automotive radar product line director at ADI explores the evolution of radar in the automotive industry and the advances in modern perception technology
A
ll assisted driving systems rely in part on multiple forms of perception
technology. In fully autonomous vehicles, optical technologies such as LIDAR (light detection and ranging) and visual cameras will work alongside electromagnetic motion sensors (accelerometers, gyroscopes, and magnetometers) and RF/microwave systems (radar and satellite positioning). Demand for ever higher levels of driver
assistance, supported by the evolution of functions such as AEB and adaptive cruise control (ACC) in new ADAS implementations, are driving suppliers such as Analog Devices to develop new radar systems that offer higher precision, longer range, faster detection, and a more complete picture of the technology for two reasons: safety and comfort. Driver assistance systems such as AEB and ACC save lives and prevent accidents. Cars that feature these systems are rewarded with a higher official NCAP safety score, a mark that lifts the value and consumer appeal of new cars. Both AEB and autonomous emergency
steering systems continue to evolve in scope and complexity to serve the growing market for vehicles in the Level 2 or Level 3 (L2/L3) categories of driver assistance technology. New NCAP specifications, for example, call for better detection of pedestrians - vulnerable road users, in NCAP’s terminology. Developing AEB systems will operate reliably in more complex events than they are typically specified for by controlling the braking function at higher vehicle speeds in both urban and highway settings. The market is also responding to
signals from car buyers who want technology to reduce the effort involved
in driving, particularly on the motorway. Premium cars such as the Mercedes-Benz S-Class already offer limited highway autopilot capabilities, such as adaptive control of distance to the car in front and active steering lane assistance. The move toward higher L4 and L5
autonomy, which isolates the driver entirely from direct control of the vehicle, will require the development of sensing systems that have a 360° view around the car in real time. The control systems for these robotaxis will be incredibly complex and will need redundancy to eliminate the risk of false detection events, combining the inputs from separate sensor types such as radar, cameras, and LIDAR. Visual cameras can be used to assist the
recognition of objects such as human beings, animals, and road signs. LIDAR technology creates rich point clouds, taking an instantaneous measurement of the vehicle’s distance from objects in the outside world and measuring the objects’ sizes to produce a high resolution 3D map of the outside world. Crucially, radar performs 4D sensing,
with a single shot, it can measure the range, velocity, angle, and elevation of an object from which its millimetre wave pulse is reflected. A radar sensor also operates in conditions, such as rain, fog, and snow, which impair or disable the operation of LIDAR sensors and visual cameras.
HIGHER PERFORMANCE, GREATER INTEGRATION Automotive radar systems under development will, in time, make today’s radar technology appear blunt and limited in comparison. Today, a radar sensor mounted in the front bumper does an excellent job of measuring the distance to a single vehicle in front and its speed.
/ ELECTRONICS Figure 1:
Super radar and imaging radar, the eyes of the vehicle
A full highway autopilot system,
however, will need to be able to operate safely on the Autobahn in Germany, where a motorbike, for example - smaller, and so harder to detect than a passenger car - can approach on the outside lane at speeds higher than 180km/h. To provide early and accurate detection of such a hazard, an autopilot’s radar system therefore needs to sense more precisely, faster, and at longer range. At Analog Devices, a new generation of
radar components, including 76GHz to 81GHz monolithic microwave IC (MMIC) transmitters and receivers, are based on a new Drive360 28nm CMOS technology platform. Marking a departure from the industry’s conventional use of SiGe semiconductor technology for radar, the Drive360 platform provides valuable
advantages including: • High output power and low return noise for detection of objects at a longer range
• Low phase noise and high intermediate frequency (IF) bandwidth, giving ultrahigh precision for the detection of small objects such as motorbikes and infant pedestrians
• High performance phase modulation, enabling the radar sensor to discriminate more effectively between multiple objects in a scene
• Ultrafast pulse transmission, giving a faster response to fast moving objects A combination of advanced
semiconductor technology, analogue expertise, and system software capability will enable radar technology to extend the capabilities of ADAS deployed in next generation vehicles.
Analog Devices Inc.
www.analog.com
ELECTRONICS | SEPTEMBER 2020 5
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