**5.3 Radar**

RADAR is meant to define its full form "Radio Detection And Ranging.". By this sensor, the object is detected with the identification of localization of objects using radio waves with a frequency range from 24 to 77 GHz. It is noteworthy to mention that the higher measurement of accuracy with respect to distance and speed along with precise angular resolution depends on high intensity of radio wave frequency. Generally the frequency over 24 GHz is used for the smaller antenna size with the lower interference problem. The examples of various types of frequency band [12] used for different sensors are as under:

**223**

**Figure 9.**

*three-sensor-types-drive-autonomous-vehicles*

*Driver Assistance Technologies*

• Emergency braking,

• Automatic distance control

Radar configurations can be broadly categorized into three categories namely short-range radar with a maximum distance of about 30 meters, medium range radar with about 60 meters and long- range radar with about 250 meters. It may be mentioned that the use of Short Range Radar is increasingly seen with the detection of blind spot, rear and forward mitigation, parking assist etc. On the other, there are a number of detection system namely forward collision warnings, cross traffic alert, stop & go etc. operated by Medium Range Radar. So far there is no specific distinction made between SRR and MRR by the industry. It is seen now a days that ultrasonic sensors and highly automated driving are gradually replaced by the SRR. We do not have as such specific definitions and distinctions between the SSR and MDR as formulated by the industries. As far as the placement of sensors in the vehicles, the forward looking sensor for long range detection is generally placed in the front of the vehicle. For a 'cocoon' radar system, extra sensors are placed on each side mid-body. Ideally, these radar sensors work on the 79-GHz frequency band with a 4-GHZ bandwidth. It may be mentioned that, global frequency specifications so far allow only 1 GHZ bandwidth at 77 GHz. Now a days a radar MMIC (monolithic microwave integrated circuit) comprises of three transmission channels (TX) and four-receiver channel (RX) to be monolithically integrated. Whether it creates a sense to integrate base band processing in the monolithic microwave integrated circuit (MMIC) or whether it is better to concentrate on a raw data radar sensor, it is a matter of debate. The difference is that the output of the baseband processor provides so called pre-targets. In this case, data is pre-processed such as unverified information on speed, distance, signal strength, horizontal angle, and vertical angle for each detected object. The raw data radar sensor presents unfiltered raw data, to the ECU for processing. **Figure 9** demonstrates the architecture of such a raw data radar sensor. The radar sensor used as partitioned simplifies the data fusion of the video and radar data, and LIDAR data since the same communication interface can be used A prerequisite for the development of MWICs (Millimeter Wave Integrated Circuit)

*Radar architecture for processing of raw data. Source: (https://www.sensorsmag.com/components/*

• Park Assist

• Brake Assist

*DOI: http://dx.doi.org/10.5772/intechopen.94354*

Short-range radio applications include:


*Driver Assistance Technologies DOI: http://dx.doi.org/10.5772/intechopen.94354*

• Park Assist

*Models and Technologies for Smart, Sustainable and Safe Transportation Systems*

technique using Avalanche Photodiodes along with internal amplification measure the light pulses in the nanosecond range across wider bandwidths. Lidar optical system requires the high spatial resolutions. Therefore sensor has the capability to develop APD arrays comprising with multiple sensor elements. The APD arrays from sensor addresses the effect of temperature due to its high voltage. Their highly accurate amplification offers excellent APD signal quality. The modules can be adapted to as per the specific application. Development boards with digital output signal and Low Voltage Differentiating Signal (LVDS) is interfaced. With the help of Lidar and Radar System, the object of the road can easily be identified. But in addition to these, there is a necessity for a camera for classification and detection of an object in a correct way. With the development of point density cloud from the reflections from radar and lidar, the distance and closing speed of the object can easily be measured. It may be mentioned that due to lower resolutions from these sensors as compared to camera, the detection of the objects are not easily made. To optimize the detection at varying ranges with lower resolution, a number of units are installed from a medium-range unit for emergency brake assist to long-range radar for adaptive cruise control although LIDAR & radar, functions in a similar

*Principle of the functioning of LIDAR. Source: https://www.fierceelectronics.com/components/*

RADAR is meant to define its full form "Radio Detection And Ranging.". By this sensor, the object is detected with the identification of localization of objects using radio waves with a frequency range from 24 to 77 GHz. It is noteworthy to mention that the higher measurement of accuracy with respect to distance and speed along with precise angular resolution depends on high intensity of radio wave frequency. Generally the frequency over 24 GHz is used for the smaller antenna size with the lower interference problem. The examples of various types of frequency band [12]

way at longer ranges with lower point-density.

used for different sensors are as under: Short-range radio applications include:

• Blind Spot Detection (Blind Spot Monitoring)

• Rear end radar for collision warning or collision avoidance

• The lane and the lane-change assistant

**222**

**5.3 Radar**

**Figure 8.**

*three-sensor-types-drive-autonomous-vehicles.*


Radar configurations can be broadly categorized into three categories namely short-range radar with a maximum distance of about 30 meters, medium range radar with about 60 meters and long- range radar with about 250 meters. It may be mentioned that the use of Short Range Radar is increasingly seen with the detection of blind spot, rear and forward mitigation, parking assist etc. On the other, there are a number of detection system namely forward collision warnings, cross traffic alert, stop & go etc. operated by Medium Range Radar. So far there is no specific distinction made between SRR and MRR by the industry. It is seen now a days that ultrasonic sensors and highly automated driving are gradually replaced by the SRR. We do not have as such specific definitions and distinctions between the SSR and MDR as formulated by the industries. As far as the placement of sensors in the vehicles, the forward looking sensor for long range detection is generally placed in the front of the vehicle.

For a 'cocoon' radar system, extra sensors are placed on each side mid-body. Ideally, these radar sensors work on the 79-GHz frequency band with a 4-GHZ bandwidth. It may be mentioned that, global frequency specifications so far allow only 1 GHZ bandwidth at 77 GHz. Now a days a radar MMIC (monolithic microwave integrated circuit) comprises of three transmission channels (TX) and four-receiver channel (RX) to be monolithically integrated. Whether it creates a sense to integrate base band processing in the monolithic microwave integrated circuit (MMIC) or whether it is better to concentrate on a raw data radar sensor, it is a matter of debate.

The difference is that the output of the baseband processor provides so called pre-targets. In this case, data is pre-processed such as unverified information on speed, distance, signal strength, horizontal angle, and vertical angle for each detected object. The raw data radar sensor presents unfiltered raw data, to the ECU for processing. **Figure 9** demonstrates the architecture of such a raw data radar sensor. The radar sensor used as partitioned simplifies the data fusion of the video and radar data, and LIDAR data since the same communication interface can be used A prerequisite for the development of MWICs (Millimeter Wave Integrated Circuit)

#### **Figure 9.**

*Radar architecture for processing of raw data. Source: (https://www.sensorsmag.com/components/ three-sensor-types-drive-autonomous-vehicles*

is dedicated high-frequency (HF) technologies to realize the frequencies (24 GHz or 77 GHz) and the corresponding output power. **Table 2** presents *summary table of the properties of a radar sensor in certain ADAS.*

Multiple transmitters and receivers are generally are in-built to determine range, angle, and velocity of objects in their field of view. As various sensors are concerned, it consists of ultra-short-range- radar (USRR), short-range-radar (SRR), mediumrange-radar (MRR), and long-range-radar (LRR) sensors or systems.


#### **Table 2.**

*Summary table of the properties of a radar sensor in certain ADAS, source: Ref. [12].*

**225**

**Figure 10.**

F = 40 kHz Distance range: 0 to 3

+/− 5°

**Table 3.**

meter Distance accuracy: 10 cm Angular range: 120° Angular accuracy:

Response time: 60 ms

*how-smart-sensors-enhance-adas-designs/*

*Driver Assistance Technologies*

**5.4 Ultrasonic sensing system**

*DOI: http://dx.doi.org/10.5772/intechopen.94354*

The primary philosophy of working with the ultrasonic technology is to transmit short bursts of sound waves that return back after hitting objects for which the measurement are to be taken in terms of time required to bounce back with speed of approximately 346 m/s which is the speed of the sound. For detection of short distance range obstacle, Ultrasonic sensors are increasing being used in the automobile industries which is generally characterized by with a sound pressure kHz and detection covering range of one to three meters supported by horizontal beam width of maximum100°and60°vertical. The ultrasonic and radar technology

Ultrasonic sensing is generally meant for short-distance applications at low speeds, such as park assist, self-parking, and blind-spot detection. For maximum coverage, an automotive ultrasonic system typically performs with multiple sensors placed in the wing mirror and front and rear bumpers. Ultrasonic sensing is a more cost-effective approach than cameras, which have poor close- distance detection. Though infrared sensing is cheaper than ultrasonic, it's less accurate and cannot function properly in direct sunlight. Objects closer to the transmitter generate a stronger echo than an object with more distantly located. In order to avoid false

complements each other to determine the higher degree of accuracy,

*This ultrasonic system features a PGA450 analog front end (source: Author/PGA450-Q1 PDF).*

**Property Present in systems Comment**

• Obstacle & Collision Warning

*Summary table of the properties of an ultrasonic sensor in certain ADAS, source: https://www.embedded.com/*

• Pre-Crash Collision and Mitigation System

In adverse weather conditions
