mmWave Radar for Automotive Cabin Monitoring and Child Presence Detection

Date: February 7, 2020

Author: Akshay Srinivasa

Safety is one of the top priorities for new-age buyers. Governing bodies across the world are changing the way they evaluate cars, giving top priority to various safety features the car has to offer along with traditional crumple zones and airbags.

What do the regulatory bodies say in this front?

Euro NCAP and NHTSA (USA) are two of the top governing bodies evaluating new cars for their safety and features. Rising awareness on the issue of fatality of children left behind in a car has forced the regulators to have a look at means of proactive child presence detection or safety monitoring system. With Euro NCAP taking the lead on this, cars equipped with child presence detection or safety system will be awarded a substantial score over the cars that are not equipped.

Euro NCAP guideline states - “Leaving an unattended child in a parked car, even for a few minutes, can cause heat-stroke and death. Child deaths from vehicle-related heat-stroke happen less frequently than those resulting from crashes, but the nature of these entirely avoidable deaths deserves special attention. A child’s inability to exit the vehicle on his/her, own combined with a low tolerance for high temperatures, requires that children never be left unattended in a car. Technological solutions are available that can monitor a child’s presence in the vehicle and alert the car owner or emergency services should the situation become dangerous. Euro NCAP will reward manufacturers that offer such solutions as standard.”

NHTSA states – “Leaving an unattended child in a parked automobile can lead to heatstroke and death, even if only left for a few minutes. Child deaths from automobile-related heatstroke occur with a lower frequency than those that occur in traffic crashes, but the nature of these completely preventable deaths warrants special attention. A young child’s inability to exit the vehicle on his/her own combined with a low tolerance for elevated temperatures requires that children never be left unattended in an automobile. The National Highway Traffic Safety Administration has conducted research and supported public awareness efforts in an attempt to address the problem of children dying of heatstroke after being left unattended in a parked vehicle or by gaining access to a parked vehicle. The largest subset of fatalities is children who have been unintentionally left in the vehicle by the driver or caregiver upon arrival at the destination.”

Needless to say, carmakers are quickly adopting solutions to address this. Just to make it more interesting, here are the points awarded to new cars for incorporating child presence detection and other cabin monitoring features.

NCAP relevance to cabin monitoring

NCAP relevance to cabin monitoring
FeaturesYearPoints awardedDescription
Seat belt reminder20202.0Applicable to all 5 passengers in a car
Child presence detection20221.01.0 Child presence detection and warning if left behind
Child left behind monitoring20224.0Child left behind detection and alarm in case warning is not heeded
Driver state monitoring20201.0Vital signs like heart & breathe rate


Means to develop a child presence detection system

There are various technical approaches that can be followed to develop child presence detection. The two most common approaches would be to use either a camera or a radar as a primary sensor to develop the system. Even though both camera and radar are capable of sensing occupants in the car, a radar-based solution is typically preferred as it has numerous developmental and privacy advantages.

Using radar for child monitoring

Radar, with its versatility, can be used across various applications in the automotive cabin. Some of the applications where radar fits right in are listed below-

  • Left out child and pet detection in a locked vehicle
  • Seat belt reminder
  • Driver health status monitoring including heart and breathing rate

Some might argue that the same features can be achieved with a camera sensor. However, they come with their own disadvantages, some of which are listed below:

  • Camera-based systems are usually associated with privacy-related issues
  • Objects behind the front passenger seats are not monitored completely like in between two rows of a seat which is outside the camera Field of View (FoV)
  • Accuracy of the solution in cases such as when a child is covered with a blanket is low

With numerous advantages under its belt, radar is all set to be the go-to sensor for left out child monitoring/cabin monitoring. Radar range is typically classified as short-range, medium-range and long-range (SRR, MRR & LRR). For cabin applications, SRR is preferred. The field of view is configured for each model of a car based on the cabin dimension and position of the radar sensor. This makes it easier for the system to detect and classify (adult & child) living and non-living beings.

Radar is the way ahead

Very soon, OEMs will be offering child monitoring and cabin sensing features as a standard feature on all of their offerings. Radar, as the sensing technology, fits the application requirements while also curtailing the privacy concerns that other sensing technologies such cameras have.

Some of the leading sensors for cabin monitoring are Texas Instruments’’ xWR1642, xWR1843, xWR1243, xWR68xx, NXP’s TEF810x and more. If you are looking to develop radar-based in-cabin monitoring solutions, do reach out to us! PathPartner offers highly customizable and optimized radar SDK for various radar applications. This radar SDK is also capable of clearly distinguishing/ classifying living things, which is well suited for an application like child monitoring and alert.

Further reading

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