Child Presence Detection Systems Save Lives

In 2022, at least 33 children died of hyperthermia or heatstroke in the U.S., either because they were left unattended in a vehicle or because they independently gained access to an unoccupied vehicle. In the last 25 years, 942 children have died in the U.S. due to heatstroke, and several thousand children have suffered adverse health effects (Figure 1). To prevent these tragic outcomes, the U.S. Federal Communications Commission (FCC) and New Car Assessment Program (NCAP) have drafted regulations requiring OEMs to install child presence detection (CPD) systems in new cars.

From 2025 onward, classification will be mandatory to achieve the highest safety star rating. A child or baby alone in a car must be detected within 10 seconds based on FCC regulations. A warning must then be issued to remind the vehicle user of the child and the associated health risk, or even make outsiders aware of the child. Car manufacturers will be able to make their cars safer and achieve a five-star NCAP rating by utilizing a CPD system.

This matches the trend in in-cabin monitoring system (ICMS) applications. Yole Group expects unit sales to continue to grow in the coming years, with a CAGR of more than 50% (Figure 2). This market development is driven by NCAP regulations (such as the adoption of CPD systems by 2025), government initiatives to reduce fatalities and OEMs’ voluntary commitments to improve occupant safety.

The needed technology

The most promising technology for ICMS in general and for child presence detection in particular is radar, allowing the detection of target objects in the car. By detecting movements caused by breathing and heartbeats, the radar can distinguish between lifeless objects and living beings. Moreover, the classification is easy for adults and children. The sophisticated sensor technology works without direct line-of-sight and through materials, so the design of the interior is not disrupted by visible lens covers or similar gear. Radar sensors are cheaper and smaller than cameras, consume less power and require less processing overhead. Privacy is also protected with radar sensors, as no images are captured.

Infineon 60-GHz radar solutions enable OEMs to deploy such child presence detection systems with very high accuracy (over 99%), combining ease of use with very low system cost. Just one radar sensor in the overhead compartment can cover a whole five-seater car, including corner-case areas like the footwells (Figure 3). The fully Infineon-based system concept includes not only Infineon radar sensors but Infineon AURIX™ microcontrollers with the necessary processing power to run the highly efficient detection algorithms. It detects a child alone in the car within seven seconds—faster than the speed required by the regulations. If a left-behind child is detected, OEMs or Tier 1s can trigger an alert/warning to the user based on the CPD information.

Infineon’s CPD system was extensively tested, and the machine-learning algorithms were trained with real adults and children. Corner cases like footwells and non-living objects like water bottles were also tested. This very reliable system avoids false alarms, which would be a nuisance for the car user. Currently, Infineon is working with its partner NOVELIC (see below “A strong partner for advanced CPD systems”) on algorithms that can also distinguish between children and pets.

Additional applications with just one sensor

The very high thermal efficiency of radar sensors enables a size- and cost-optimized solution. And beyond that, radar technology allows additional applications with only one sensor (Figure 4). This diversity streamlines the bill of materials and further optimizes cost efficiency.

Infineon’s CPD solution can be used simultaneously as a seat occupancy detection system. A single antenna-in-package (AIP) sensor reliably detects and localizes all five passengers in a car. Occupant localization combined with classification can be used by OEMs and Tier 1s to optimize seatbelt reminder systems. This eliminates the need for the traditionally used weight sensors in the seats and the associated wiring harnesses, saving costs in the range of €1.50 to €8.00 per seat. The distinction between adults and children enables the optimization of airbag deployment systems on the passenger seat.

The Infineon system enables even more benefits: Intrusion and proximity alerts can be implemented with the same sensor to increase the safety and security of the car. Tier 1s and OEMs can develop an alarm/alert system that notifies the user about unauthorized access within 300 ms—for instance, if a hand enters through a window, the sunroof or the trunk. To react even faster, the car’s immediate surroundings can also be continuously monitored. If someone jiggles the car or tries to break in, an alarm system can be triggered that flashes the headlights or honks the horn to ward off potential intruders.

Automotive AIP sensors

Infineon has been a recognized leader in automotive radar for many years. Its market leadership, with over 70% market share for 77-GHz radar and with over 100 million units of 24-GHz BSD radar sensors sold, proves the company’s know-how and experience. Infineon is also very successful in the consumer sector with 60-GHz radar, which is used in market-leading smart TVs, smartphones and more.

The two automotive AEC-Q100 Grade 2–qualified sensors BGT60ATR24AIP and BGT60ATR24C, which are used in the child presence detection solution, also come from this family of consumer radar sensors. The modular approach creates the most flexible solution on the market.

Furthermore, Infineon already has long-standing know-how regarding AIP technology, which the company was the first to introduce to the market with a consumer product. Now, with the BGT60ATR24AIP, the technology is also coming to automotive applications. Tier 1s and OEMs benefit, as they do not have to design any antennas on the PCB. This reduces time to market and R&D efforts on the customer side.

Despite the integrated antenna, the AIP sensor is very compact, at just 8 × 8 mm². Due to its excellent thermal management, the sensor remains cool in operation even without a heatsink, consuming only 50 mW. Together with the AURIX™ TC3xx microcontroller, a single sensor is sufficient to monitor even the footwells.

Conclusion

Every year, children who have been left alone in a hot car lose their lives. That’s why the FCC and NCAP have drafted regulations that require cars to have child presence detection systems in the future. Infineon considers 60-GHz radar to be the best technology for this purpose. Thanks to its many years of experience in automotive radar, the company has been able to develop a system that can monitor a five-seater car, including the footwells, with a single sensor.

A strong partner for advanced CPD systems

Infineon’s child presence detection system was developed in cooperation with Preferred Partner NOVELIC. NOVELIC is a high-tech company with a strong team of experts in system design, analog and digital integrated microelectronics, signal processing, mechanical engineering and embedded microcontroller-/FPGA-/ASIC-based design. The company develops automotive radar monitoring systems based on state-of-the-art Infineon radar MMICs and MCU solutions.

NOVELIC’s unique development approach includes full custom design or customization of antenna systems, including signal processing and sensor-in-package modules. Its core competencies lie in the areas of software and algorithms, antenna design and verification, EuNCAP-based system testing and verification, and on-site support for system demonstration and optimization.

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