Over the past decade, radar sensors have evolved into a mature sensing modality for automotive and industrial applications. Because radar technology enables designs that require long range, environmental resilience and higher sensing resolution, it is well suited for applications in advanced driver assistance systems (ADAS) such as collision detection and fluid level detection.
Radar technology is changing with the introduction of complementary metal oxide semiconductor (CMOS)-based system-on-chip (SoC) radar sensors for applications such as parking assist, kick-to-open (KTO) sensing, door obstacle detection, robotics and e-bikes. Easier to develop and deploy.
To meet the needs of cost- and power-constrained automotive and industrial applications, current 77GHz radar SoC sensors require a new design architecture. Devices such as the TI (Texas Instruments) AWRL1432 and IWRL1432 SoCs feature power management capabilities that quickly switch between different power states and effectively run internal components such as radar front-ends, digital processing cores, or memory when needed. The device also reduces average power consumption from more than 1W typical to less than 5mW (depending on the chirp configuration), giving hardware designers greater flexibility in thermal performance designs and by eliminating heat dissipation. processor and simplify printed circuit board design to reduce costs.
1. Enable new, more flexible installations with software-based radar
An automaker's choice of sensing method often depends on the purpose of the sensor in the vehicle. For example, when the vehicle is parked and locked, the kick-to-open (KTO) sensor should be in standby detection mode. To prevent draining a vehicle's battery while parked, automakers have traditionally opted for low-power sensing methods such as capacitive or ultrasonic. Unfortunately, these types of sensors face certain challenges in terms of error detection, environmental reliability, and performance identification. Low-power 77GHz radars such as the AWRL1432 consume less than 3mW of standby detection power, improving identification accuracy in any environmental condition and helping to simplify installation, thereby reducing overall system deployment costs.
Radar sensors can be configured to dynamically switch to different operating modes based on the need for low power or high performance. Taking KTO sensing as an example, the device can operate in sub-3mW standby detection mode and then switch to high-performance mode after detecting a person for kick gesture recognition and error detection, as shown in Figure 1.
Figure 1: An AWRL1432 radar sensor dynamically switches between low-power and high-performance modes
In the field of ADAS, traditional parking assistance systems using 8 to 12 ultrasonic sensors plus camera sensors are now evolving into more powerful and cost-effective automated systems. While each ultrasonic sensor can be cost-effective, the main disadvantages are the impact of the sensor on the car's aesthetics (due to the need to drill holes), poor performance in harsh environments, and distance detection performance (minimum and maximum measurable distances) Not good.
Instead of adding more ultrasonic sensors, automotive designers can now take advantage of corner radar sensors with park assist capabilities and the cost-effective TI AWRL1432 integrated radar SoC to cover the field of view around the car, as shown in Figure 2. The AWRL1432 ultra-short range radar sensor can detect stationary objects as close as 3cm and as far as 15m, depending on the antenna configuration.
Figure 2: Using radar sensors to achieve 360-degree parking assistance coverage
As shown in Figure 3, you can use the same sensor in the center of the vehicle bumper for park assist and KTO, and a corner sensor for park assist and blind spot detection. To achieve this multi-mode capability, radar sensors must not only be software configurable but also have the architectural flexibility to scale from high performance to low power on demand.
Figure 3: Multi-mode radar sensor for parking assistance and KTO
2. Use low-power radar sensors to operate in harsh industrial environments with ease
Ultrasonic sensors are widely used for object and person proximity sensing in non-automotive applications, such as vehicle access control within parking lot guardrails or collision avoidance for off-highway vehicles such as construction forklifts, agricultural machinery, and e-bikes, as shown in Figure 4. In view of the increasingly higher accuracy requirements, 77GHz radar sensors will gradually replace ultrasonic sensors. The lower cost of the IWRL1432 helps make parking barrier sensors more affordable to implement and deploy in a smaller form factor. The high RF performance of these sensors also makes them suitable for object detection and deployment on e-bikes, scooters and agricultural equipment. These devices need to detect objects and people at distances from 1m to more than 60m.
Figure 4: 77GHz radar sensor that meets sensing challenges in harsh environments
As shown in Figure 5, tank level sensors measure liquid and solid levels in industrial environments by emitting radio waves that reflect off liquid or solid surfaces such as chemicals, oils, or liquids. Measurements even under steam, foam and other challenging conditions. The main requirements for such applications are lower power consumption, high detection accuracy and worker safety. The 77GHz IWRL1432 sensor has a built-in deep sleep mode that consumes less than 10mJ per measurement, complies with Safety Integrity Level 2 standards, and provides millimeter-level measurement accuracy.
Figure 5: 77GHz radar sensor installed on the top of an industrial liquid tank for liquid level measurement
3. Conclusion
Ultrasonic and capacitive sensing sensors for automotive or industrial applications present their own design challenges. Low-cost, low-power devices in radar sensing not only help address these design challenges but also open the door to emerging applications around vehicles or in industrial environments.