Understanding Radar for automotive (ADAS) solutions.- Mechdor

 Understanding Radar for automotive (ADAS) solutions.

Introduction of Radar:-

Ever since radio waves were discovered and their ability to reflect on objects was understood, engineers have been finding newer applications based on their detection & ranging properties. The technique, called Radar (Radio Detection and Ranging), works on the principle of a source transmitting the radio wave, being reflected by a surface, and received and processed by a receiver system. 

                                                                         Once such applications, where RADAR is seeing an unprecedented uptake, are the automotive application and more specifically ADAS solutions that deliver enhanced safety and comfort.

So, what does a Radar system consist of?

Most simplistically, a radar system typically consists of the following sub-systems:-

• Transmitter:- Powered by amplifier signals are generated here using a waveform generator.

• Waveguides:- As the name suggests, they facilitated the transmission of radar signals.

• Antenna:- Transfers the transmitter energy to the signal space.

• Receiver:- Used for the detection and capture of signals.

• Processing unit:- Users captured signals and their properties to derive detection, ranging, and other useful information.

Automotive radar typically works on 77GHz and falls into three categories:-

• Short-range radar (SRR)- 0.5 to 20 meters

• Medium range radar (MRR)- 1 to 60 meters.

• Long-range radar (LRR)- 10 to 250 meters.

Applications of Radar in automotive:-

With autonomous driving gaining traction and regulatory bodies across countries mandating the inclusion of certain security features, the adoption of advanced driver assistance systems is on the rise. Several different sensing technologies are being used currently, including radar, LIDAR (Light Detection and Ranging), infrared (IR), ultrasonic, and camera-based. Each of these technologies has advantages and disadvantages,s and most of the ADAS systems today rely on multiple technologies to provide reliable solutions to the market.

One of the key applications of Radar in ADAS  is blind-spot monitoring, object detection and collision warning and mitigation. Both blind-spot monitoring and object detection work on the radar technology systems that use the data from the radar-based system and take preventive measures like counter-steering and braking to avoid any accidents.

• Object detection systems currently in use utilise vehicle parking assist cameras to detect objects when the vehicle is relatively at a lower speed. However, at highway speeds, these systems do not work as intended. As a result, radar-based systems are used for object detection at highway speeds. To understand more about radar-based detection applications. 

           Customer, an Asian ADAS equipment manufacturer, had developed a custom radar hardware based on TI’S AWR12xx. But it was facing issues related to latency in object detection for the forwarding collision mitigation application.

• Blind-spot monitoring systems currently in use are based on other technologies. The drawbacks of these systems are that they are best suited for metallic objects alone, do not typically work well for curved objects, and their operation is affected by temperature and humidity. These systems also have a limited operating range.

Advantages of having radar-based driver assist systems over other sensors:-

It is known that radar works on the principle of transmitting and receiving radio waves after reflection, while other sensors, such as cameras, LiDAR, and ultrasonic systems are prevalent, radar-based systems have some inherent advantages, such as:- 

• Radar is touted to be an all-weather solution. Real-world working conditions,s such as temperature, humidity, etc., do not affect the functioning of radar-based systems. One of the key advantages of radar is that it works seamlessly under varying lighting conditions- night or day.

• Long-range radar systems can see really far- LRR can comfortably handle between 3 and 250 meters range.

• Materials that are generally considered insulators, such as rubber, do not affect radar-based systems.

• It is relatively easier to accurately measure the velocity, distance, and exact position of the object using radio waves.

• Radar can easily differentiate between stationary and moving objects, which is one of the major shortcomings of proximity sensor-based systems.

• When used in conjunction with existing camera-based systems, a 3D image can be created by the use of radar, using angle detection of the object and sensor fusion with existing camera-based data.

Shortcomings of the radar-based ADAS system:-

Even though radar-based systems have an upper hand over proximity-based systems, there are quite a few shortcomings of these systems.

• Detecting small objects with Radar is relatively difficult for shorter wavelengths.

• Static object detection whose relative velocity is exactly that of the moving object, obtaining the necessary reading is quite difficult and requires proprietary algorithms to address this issue.

• Existing radar-based ADAS systems do not work well in closed environments such as tunnels and usually go into standby mode.

• Radar-based systems have their limitations when it comes to recognising and classifying objects.

• Interference from other radar systems, which causes accuracy problems.

• Time is taken in actual detection, and a warning sign to the driver is on the higher side; this requires serious intervention in reducing processing time so that the warning and other precautionary measures are taken as quickly as possible.

Conclusion:-

Radar is not only economical compared to other technologies but also provides a wider range of applications. It is a proven technology and, with advances in customised software algorithms, is fast becoming one of the most visible options for car manufacturers and OEMs who foresee ADAS and autonomous driving as the future of mobility.