77Ghz single-chip millimeter wave sensor enables automatic parking

Have you ever spent time looking for a parking spot at a shopping mall or grocery store, wishing you could just get out of the way at the entrance and park yourself, especially if it’s raining or extremely hot? How much time would you save if you didn’t have to look around for a parking spot? (Or how much would you save if you didn’t have to pay for valet parking?) Self-parking will soon be a reality, and automakers are using millimeter wave (mmWave) radar sensors to make it happen.

You might be wondering: do surround cameras and ultrasonic sensors already enable parking? Today’s sensors provide parking assistance, which means the driver still has to make a judgement call based on the feedback from the sensors. So the car is still not fully autonomous.

　　Autonomous parking needs to first identify an empty parking space or "free space" at a distance of about 40 meters. This is its "search mode". Once an open space is identified, the car needs to maneuver into it and park, which is called "parking mode".

　　To enable automated parking, sensors should be able to detect objects ranging from 3 cm to over 40 m across a wide field of view, including other vehicles, curbs, and pedestrians, in all environmental conditions. mmWave sensors help achieve this by accurately detecting smaller objects at distances less than 25 cm (such as metal bars protruding from the ground), which may not be effectively sensed by other sensing modes. mmWave sensors can also continue to operate in a variety of weather and lighting conditions.

　　Sensor Installation

　　Installing sensors in cars is a major challenge today. Since mmWave sensors can be easily installed behind the bumper, car owners do not need to drill holes in the body or chassis. The ability of mmWave to pass through solid materials such as plastics and bumpers without hindrance allows for standardized installation regardless of car manufacturer or car model. The number of sensors required to achieve 360-degree sensing capabilities around the car is also much smaller than other sensing modalities. Only eight sensors are required around the car to achieve 360-degree sensing, as shown in Figure 1.

　　Figure 1: mmWave sensors can provide 360-degree sensing around the car to enable automated parking applications

　　Multi-mode sensor

　　Automatic parking is achieved by repurposing existing front and rear corner radars (multi-mode). When the car is in driving mode, these sensors can be used as blind spot detection sensors or lane change assist sensors, which can support detection of cars in other lanes within a distance of 80 meters. When the car is in search or parking mode, the configuration of the sensors changes dynamically to enable sensing of close objects, ranging from 40 meters to less than 10 cm to match the range of parking applications. Multi-mode obstacle detection sensors for the doors can also be used for parking applications. Based on these features, mmWave sensors are becoming increasingly attractive to top automakers. Table 1 lists the advantages of using mmWave sensors for automatic parking applications.

　　Table 1: System-level benefits of using mmWave sensors for automated parking applications

The AWR1843　　from Texas Instruments (TI) is a 77 GHz single-chip mmWave sensor that integrates digital signal processing, memory, and a radar acceleration unit to enable automated parking applications, as shown in Figure 2.

　　Figure 2: Components of the AWR1843 parking chip

　　Table 2 shows the application advantages of AWR1843 :

　　Table 2: AWR1843 device features and application advantages

　　Automakers and top OEMs are increasingly adopting mmWave sensors to provide various driver assistance and automatic parking features. This is mainly due to the features and advantages offered by mmWave - higher integration, (meaning smaller size). It can help autonomous driving.