Advantages of In-cabin Sensing using Camera and mmWave Radar

Date: July 27, 2020

Author: Anchal Pandey

Though every technology plays an important role in the development of autonomous vehicles, sensors are critical in improving road safety. Out of all of the sensors available, radar sensor using mmWave technology provides higher accuracy and flexibility for various in-cabin sensing features. Generally, sensors are used for the purpose to check static and dynamic objects on the road. But radars can be as useful inside the vehicle as it is on the outside. The combination of radar and camera can give an easy and effective solution for in-cabin sensing. These in-cabin sensors play a very important role in occupant detection and driver monitoring.

Why mmWave radar?

Automotive radar system can be classified based on their range of sensing objects:
  1. Short Range: They can detect up to 30 m of distance from the vehicle. They are primarily placed in the rear corners to perform blind spot detection, read collision warning and cross-traffic alert and parking assistance.
  2. Mid and Long-range: Medium range radar is in 30-80 m range and Long-range radar is for more than 80 m range. These can operate in 76-81 GHz of frequency range. These are used for AEBS (Advanced Emergency Braking System) and ACC (Adaptive Cruise Control) technologies.
millimeter-Wave radar is used in automotive radar technology due to its smaller wavelength, higher resolution, accuracy and ability to distinguish between two objects. It’s very popular among automakers due to its size and high performance.

Child presence detection with mmWave Radar

NSC has reported that on an average 39 children under the age of 15 die each year from heatstroke after being left in a vehicle. As a result, HOT CARS act was created that required the Transportation Department to mandate all new vehicle to have a child presence detection system.

Child detection system

1. Child presence detection system

Euro NCAP has also added child presence detection as their roadmap feature. Although the camera-based driver monitoring system can be used to detect the child’s presence, it might not be able to function properly if it’s not under the camera’s view. Nowadays automakers use a variety of technologies such as weight sensors along with a camera to get the right result, but they too have limitations. The limitations we are talking about is the presence of low or excessive light or if the child is in the child seat is not angled correctly or if the child is covered with a blanket. In such scenarios, radar comes into play. Millimetre-wave technologies can be an effective way for child detection because it can’t be blocked. It can pass through materials such as plastic and clothing or even if they are covered by blankets. Camera-based passenger detection is useful in most of the scenarios but radar works as an add on by providing accuracy and flexibility by giving the correct count of passengers. Its uses don’t end here.

Driver state monitoring system

2. Driver Monitoring System

Along with camera-based driver monitoring system it can create an in-cabin scenario which can provide a better system for seat-belt reminder and airbag deployment. For example, a weight sensor calculates a person’s presence by measuring if the object on the seat weighs more than a certain threshold. The limitation here is that it can be anything that is equal to the size and weight of the person but radar can detect the difference between the two. In the case of airbags, the radar can detect the size of the person and whether it’s an adult or a child and deploy the airbags as per the requirements. After Hot Cars Act and Euro NCAP roadmap came into picture, automakers and Tier One suppliers are trying their best to devise an in-cabin sensor for child presence detection. The solution has to be non-intrusive and that can be easily integrated into the vehicles. mmWave radar can not only change the way the vehicles study their surrounding environment but they can also sense the vehicle’s occupants. Currently, it’s very much possible to use a single mmWave radar sensor to detect and identify the occupants and identify them as adult or a child and show their vital signs. Due to their ability to sense through solid materials, radar can easily detect an unattended child with higher accuracy than ever before. Fortunately, we have already developed such product. Want to know more about it? Leave us a mail at


RADAR-based ADAS integrated with automotive camera-based driver monitoring systems are very helpful in generating information about the vehicle occupants especially unattended children. These integrated systems along with deep learning can help in driver and passenger monitoring and result in safer and smarter driving decisions.

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