Advantages of TI's new mmWave radar sensor

Automated parking technologies are evolving as automotive OEMs develop more autonomous vehicles. These parking systems range from park assist (which still requires driver involvement) to automated parking (which can be hands-free).

Most of today's car parking systems use ultrasonic and camera sensors. Ultrasonic sensors work by sending out high-frequency sound waves that are reflected by objects in their path. The sensor measures the distance of nearby objects by measuring the time it takes from transmission to reception. However, ultrasonic and camera technologies do have certain limitations and are constrained by the following factors:

Environmental conditions such as mud and fog

Minimum and maximum detection distance

Narrow horizontal and vertical field of view

cost

Upcoming automated parking systems can benefit from TI's cost-effective millimeter wave (mmWave) radar sensors, which enable effective 360-degree surround view even in harsh environmental conditions. In addition, mmWave radar technology can provide important environmental information, such as the distance, speed and angle of nearby objects.

Radar sensors can be used in various environments

Reliability is a major drawback of other sensing technologies, such as ultrasonic, capacitive, and camera systems. Water, mud, debris, fog, snow, and low or high light levels can affect other sensing technologies, but not mmWave radar. Radar works well in a wide range of environmental conditions. In addition, radar does not require a non-metallic bumper cutout, which protects the radar sensor while maintaining the aesthetics of the car.

Why radar is better than ultrasonic in automatic parking applications

Compared to other sensing technologies, such as ultrasonic sensors, mmWave radar can detect objects at greater distances. Instead of emitting sound waves, radar sensors generate radio waves: radio waves have the longest wavelengths in the electromagnetic spectrum. These waves are reflected by objects in their path, and the change in their frequency is counted to determine the distance of the object. Because radio waves can travel farther, they have a greater detection range. By sensing objects at greater distances, more objects can be detected around the parking lot. TI's AWR1843AOP device can detect objects up to 50m away.

In addition to the maximum range limitation, ultrasonic sensors also have a minimum range limitation of about 10cm to 15cm. TI's mmWave radar can detect objects as close as 4cm, which can help drivers maneuver vehicles in narrow, tight parking spaces and detect edges approaching vehicles. The channel bandwidth of the radar is inversely proportional to the range resolution (i.e., the ability to distinguish between two or more objects). The 4GHz bandwidth of the AWR1843AOP is associated with a range resolution of about 4cm.

One of the advantages of mmWave radar sensors is their wide field of view. Figure 1 shows that ultrasonic sensors have a limited field of view. Even with more ultrasonic sensors placed around the car than radar sensors (typically up to 12), there is still a gap in detection. mmWave radar has a wider field of view, providing 360-degree coverage around the vehicle while using fewer sensors than ultrasonic sensor implementations.

While other sensing technologies, such as time-of-flight and ultrasonic, may not be able to detect objects that are much lower or higher than the sensor height, the AWR1843AOP’s 140-degree vertical field of view enables the detection of low objects such as curbs, bollards, small animals, and road debris. Figure 2 shows the use of the AWR1843AOP evaluation module (EVM) to detect a cinder block used as a low-height curb.

Detecting cinder blocks used as curbs

Due to its wide field of view and high range resolution, it can detect and differentiate multiple static objects simultaneously. Figure 3 shows the radar’s ability to differentiate between objects of several different materials, including wood, metal, and plastic, with very small surfaces.

AOP technology accelerates time to market

As automakers and Tier 1 suppliers turn to 77GHz mmWave sensors to improve the performance of detecting objects when parking, TI's AWR1843AOP mmWave radar sensor integrates the antenna, radar transceiver, digital signal processor, microcontroller, and interface peripherals all on a single chip, as shown in Figure 4. Integrating the package onto the chip eliminates the need for high-frequency substrate materials. Compared with other radar sensors, not using high-frequency substrate materials can greatly reduce cost and manufacturing complexity, while saving about 30% of board space.

Time to market can even be accelerated by eliminating the need to design, simulate and characterize antenna performance. In addition, TI's software can be reused and ported across the company's 60GHz and 77GHz devices, accelerating multi-radar system-level design.

In addition, the AWR1843AOP can be programmed to reconfigure the same sensor for multiple applications. For example, the same sensor can be used for parking and detecting objects when opening a door, or even existing radar sensors used for other functions such as blind spot detection can be reused for parking radar functions, reducing overall system cost.

The advantages of TI mmWave radar sensors include: 360-degree coverage around the vehicle; longer detection range; accurate measurement of distance, speed and angle of objects. In addition, AOP technology makes it easier to create sensors with very small form factors. TI's 77GHz AWR1843AOP radar sensor enables more flexible detection and better performance in parking applications.