Child occupant recognition introduced in Euro NCAP 2020

Sensing technology is rapidly improving safety and convenience features inside cars. On the other hand, it is becoming increasingly important to accurately determine whether people are inside the car. According to a study by San Jose State University in the United States, an average of 37 children die each year from being trapped in a hot car, and “more than half of these are due to parents or guardians forgetting that there is a child inside the car.”

Millimeter wave (mmWave) sensing technology can detect the presence of people even in very bright or dark environments. Unlike other sensing technologies, mmWave can pass through materials such as plastic, drywall, and clothing, so the sensors can be hidden behind or inside any object inside the car and operate non-contactly and non-invasively. For example, ultrasonic sensors cannot distinguish between people and stationary objects, and cameras cannot detect children in very bright or dark conditions.

TI's AWR1642 77-GHz single-chip millimeter wave sensor with on-chip memory and a digital signal processor (DSP) is well suited for these applications because it can accurately identify human presence and detect even subtle movements such as breathing.

TI used the AWR1642 evaluation module to detect occupancy inside a stationary car. For demonstration purposes, the sensor was installed on the sunroof and pointed toward the rear seat, as shown in Figure 1. In real applications, it could be installed behind the seat, in the rearview mirror, or on the roof. This sensor implements the entire processing chain for detection, including an algorithm to remove any static clutter that may be present. In Figure 1, a child is sleeping in a child seat covered with a blanket. The sensor not only detects the child covered with a blanket, but also accurately identifies the location as the right rear seat.

In Figure 2, two people are sitting side by side in the back seat. The two red boxes indicate that the millimeter wave sensor detected the two people. Since millimeter wave sensors can identify and distinguish people sitting farther away, they can also detect people sitting in multiple rows in a car.
Figure 3 detects a person outside the vehicle who may be an intruder. A sensor that detects a person inside the vehicle can also detect a person in the immediate vicinity of the vehicle. It is possible to implement an algorithm that distinguishes between people and moving objects, such as tree branches swaying in the wind.
The Vehicle Occupant Recognition Reference Design using AWR1642 provides a complete system and reference software processing chain for detecting two people inside a vehicle.

The TI Design Guide details the algorithms used here, and you can try out this demo yourself in a lab or real-world environment. You can also easily modify and extend this demo to detect multiple people.

Millimeter wave sensors are used not only in ADAS but also in body, chassis and in-cabin applications. Child occupant detection is scheduled to be introduced from 2020 according to the Euro NCAP (European New Car Assessment Program) roadmap.

Automakers and leading suppliers are looking for sensing technologies that can provide this functionality in a non-contact and non-invasive manner. Another key requirement is cost-effectiveness and solution form factor. Millimeter wave sensors meet these requirements by reducing the bill of materials (BOM) and solution size in a single chip while providing high resolution. It will be exciting to see this sensing technology used in new vehicles coming out in the future.