Completely autonomous radar sensor for smart motion sensing

By Bernd Kohler and Arushi Jain, Infineon Technologies AG  for EETIMES -Security systems, automatic doors, smart-lighting control, and other features of a smart building would not be possible without reliable motion sensors. Passive infrared (PIR) sensors are commonly used despite their significant disadvantages. Infineon has developed a compelling and cost-effective replacement to make motion sensing smarter: A one-package radar-sensing solution that enables radar technology for everyone.

Widely used PIR sensors detect the infrared radiation of a person, an animal, or an object at mid-infrared wavelengths. However, with rising temperatures, their reliability decreases dramatically. It is therefore recommended not to install them near heat sources or use them in high ambient temperatures. For more demanding environments, radar sensors are a better solution, as they are less temperature-dependent.

Another advantage of radar sensors is their superior sensitivity. PIR sensors can mainly detect larger movements along the tangential direction with a minimum speed of about 1 m/s. As a consequence, PIR sensors are ineffective for stationary and radial movement detection. In contrast, radar sensors detect the slightest movement of the human body, be it typing, speaking, or even breathing. Furthermore, you can get the direction of motion, velocity, or even exact position of a target, depending on the radar chip configuration.

Beyond that, radar sensing protects privacy, because it does not create any optical image of the sensed environment as time-of-flight or camera sensors do. Hence, radar sensing can be completely anonymous.

Given its unique features and benefits, radar has been used for decades in defense, security, and aerospace, as well as applications like weather monitoring or traffic control. In the industrial area, radar was limited to level/ground probing, maritime navigation, and motion sensors for automatic doors. Yet in the past few years, the technology has advanced significantly and will now create opportunities in factory automation, autonomous navigation, cobots, and commercial drones for industrial inspection. According to Yole,¹ the market for industrial radar applications is expected to exceed 10 million devices within the next five years, with basic motion/presence detection as the predominant use case (Figure 1).

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