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Comprehending the Impact of Radar and Lidar on Autonomous Technologies

As the price of radar and lidar technologies falls, a plethora of new applications emerge. Both automotive and medical technology sectors happen to be quick to reply to the opportunities.

Radar, short for Radio Detection and Ranging, runs using a simple principle. Transmitted pulses of radio waves bounce off objects and return as echoes. Detection is provided by the echo, the range – or distance – is calculated from changes contained in the echo.

Radar systems operate over a huge selection of frequency bands, from about 5 MHz to 300 GHz. The IEEE created a system of classification according to standard letter designations for that various bands. These designations comprise HF, VHF, UHF, L, S, C, X, Ku, K, Ka, V, W and mm. The most recent version of the standard, IEEE 521-2022,

Microwave radar, considered between 300 MHz to 30 GHz, can be used for imaging, non-contact measurement of chest motion to watch breathing, detecting a person's movement in bed for sleep tracking, and heartbeat measurement, amongst other activities. In care homes, seniors may regard radar as less intrusive than cameras, therefore it can be used for fall detection.

Unlike cameras, radar transmitters and receivers might be included in walls, so the systems don't even have to be visible. The power levels of most of these systems have been in the microwatt to milliwatt range.

Autonomous technologies predicted they are driving the biggest growth

The automotive sector is predicted to be the biggest growth sector for radar in the next couple of years as advanced driver assist systems (ADAS) and semi-autonomous and autonomous vehicles drive demand.

Today, automotive radar applications are primarily adaptive cruise control, assisted braking and blind-spot detection, but as driving autonomy develops you will see an excuse for an all-round look at other motor vehicles and a way of determining how they are moving. For instance, are vehicles in the rear-view mirror receding or getting closer, and at what rate?

The foundations of the automotive radar module are the antenna, a radio frequency (RF) front-end, along with a digital processing unit. As always, the semiconductor industry is striving for greater integration to reduce the dimensions and cost of chips and modules while increasing their reliability by minimizing the number of components needed to implement the system.

The typical selection of automotive FMCW radar systems is up to 800 feet or 250 meters. At 77 GHz, RF transmitter power levels are low, around +10 to +13 dBm for automotive systems, and many transmitters and receivers could be built-into just one monolithic microwave integrated circuit (MMIC).

In radar front ends, some exotic and expensive compound semiconductor technologies – silicon-germanium (SiGe) and Gallium arsenide (GaAs) – are now being superseded by complementary metal-oxide-semiconductor (CMOS). Up to now, these front ends haven't been coupled with microcontrollers to create single-chip systems, but that’s prone to happen soon.

For the time being, designers must use chipsets: a monolithic microwave integrated circuit (MMIC) for the transceiver and a complementary microcontroller (MCU) or system-on-chip (SoC) for data processing, as in the basic system shown below.

Automotive radar architecture type

Example of automotive radar architecture

Lidar: greater accuracy, greater speed, different limitations

Radar and lidar systems operate in broadly similar ways but while radar engineers describe their electromagnetic spectrum when it comes to frequency, lidar (optical) engineers usually discuss wavelength. The lidar wavelength range is mainly near the infrared spectrum. It spans 750 nm to simply over 1.5 um. Like radar, pulsed time-of-flight (ToF) or FMCW techniques can be used to detect and map objects in 3D.

The greatest advantage of lidar over radar is its resolution, even compared to high frequency, high-resolution radar.

Now present in smartphones, the principle of lidar isn't too challenging. However, the price of automotive-grade lidar solutions has been a significant factor limiting adoption. But cost is falling rapidly. Systems that cost tens of thousands of dollars just a few years back is now able to designed for 100's of dollars.

A $100 lidar module for automotive applications was announced in 2022, a definite illustration showing progress within the technology.

As costs have fallen, the amount of applications and potential future applications has grown, designed for lidar's 3D imaging capabilities. Applications now include from topographic surveys and soil analysis to pollution monitoring for CO2, SO2 and methane gas.

Lidar is now present in drones, robots and other types of machines. Its use within cars along with other vehicles is perhaps capturing probably the most interest from component manufacturers.

Lidar in automotive applications

As with radar, the automotive sector is viewed as a vital growth chance of lidar. Within this sector, lidar systems operate at 905 nm or 1,550 nm. The main hardware blocks of the lidar system are transmitted, receive, beam steering, optics, readout, and power and system management.

Proponents of lidar point to its ability to quickly generate detailed, accurate maps from the surroundings of the vehicle in 3D. Additionally they point out how well it can detect small objects, because of its relatively high definition compared with radar. A recent advance is really a 4D lidar, delivered from the module that not only establishes the distance to an object and its x, y, and z coordinates but can also plot velocity because the fourth dimension.

Three main factors have so far restricted more predominant adoption of lidar in the automotive world: cost, mechanical complexity (which is both an expense factor along with a maintenance headache), and performance in poor weather conditions.

The mechanical complexity of automotive lidar is a result of the requirement for a beam-steering mechanism for the lidar transmitter (a laser) and it is receiver to supply a 360-degree view around an automobile.

However, even as everything becomes simpler and more affordable, lidar is hamstrung by its performance limitations in poor weather conditions. In rain, snow and fog, it struggles with the same challenges as vision systems – human or otherwise.

Despite these challenges, most self-driving car companies have reportedly shown interest in their planned foray in to the automotive world.

Complementary technologies: vision, ultrasound and infrared

Automakers aren't relying on a couple of sensing technologies for his or her assisted and autonomous vehicles. Ultrasound is really a cheap and proven technology for parking assistants. Infrared cameras work in darkness, as well as in fog and are not affected by solar glare, so that they possess some advantages over lidar. And because the goal is for cars to be able to \”see\” a minimum of in addition to or much better than humans, video cameras complement other technologies in ADAS and autonomous vehicle designs.

Sensors present in connected cars today

Today's connected cars are bristling with sensor and communications technologies.

Most auto makers seem to believe that it’s impractical to make use of video exclusively. Processing multiple moving images at high speed requires enormous compute power that is hard to provide within a vehicle, and it takes too much time to transmit all this data towards the cloud and back.

Most vehicle makers are thus using data fusion algorithms to process a combination of video, radar, lidar and other data to produce systems with optimized capabilities.

However, Tesla continues to be vocal concerning the limitations of lidar, arguing by using the best neural (AI) processing capabilities, only vision cameras are essential. The business's cars used cameras alongside radar, however in May 2022, Tesla started shipping Model 3 and Model Y cars with driver-assist systems that depend on just eight cameras – no radar or lidar.

Technology forecasting is a dangerous business, however, many component makers are betting heavily on radar and lidar systems having a golden period of development in the coming years.

For probably the most part, the analysts go along with that idea. But vision systems and also the processors which go in them produce an exciting opportunity, too.

Courtesy: Avnet