UWB Child Presence Detection System～UWB幼児置き去り検知システム～

BackgroundChildren left in cars or school buses have become a social problem.
The European New Car Assessment Program (Euro NCAP) started the testing of child presence
detection (CPD) in 2023.

Tokai Rika’s CPD product line-up
For school buses
CPD support device

For passenger cars
Millimeter-wave radar CPD device
Product example: Front overhead
Confirmation button

Millimeter-wave sensor
Kokodayo button

The voice guide repeatedly says
“Please check the interior. Afterconfirming that nobody is inside,
press the button at the back.”

On-board speaker

Product example: Stand-alone module
The frequency of the radar signal is high.
⇒ The device boasts high performancebut the parts cost is high.

Conventional
problem

Demand for wide range of CPD products for small cars ≒ Cost reduction

Purpose
Content andOverview

Create a low-cost CPD system with UWB radar sensor for small cars
・The UWB radar sensor installed overhead of a car detects a living body inside.
・When detecting a child at the time the doors are locked, the CPD system gives warnings (hazardlamps, horns, and emails).
・The frequency of the radar signals is relatively low ⇒ Parts cost can be saved

UWB sensor

15:03

StatusConnected

Date and time
Message

A child may
be left in thecar

Strength of
Tokai Rika

Tokai Rika’s UWB communication technology gained through the development of smart and digital key
systems against relay attack support this reliable detection system.

Technology

・The multi-antenna system accurately detects whether a dynamic body is in or out of a car by determining its distanceand angle. → Fewer units can work as a CPD system.
・The multi-antenna technology that ensures the characteristics of antennas in proximity in the UWB bandwidth
detects angle accurately. (Two patents applied)

OutsideDistance + angle

UWB

Distance

The multi antenna
system can detect
distance and angle.

Distance + angle

InsideAngle

The multi-antenna system detects a body in and out of a car

Multi-antenna current distribution

・The original detection algorithm using the stationarity of phase difference between antennas detects body motions
accurately. (Two patents applied）
Received signal(IF signal)

Removal of stationary body

Feature amount by phasedifference between antennas

Detection of body motions

Body motions
detected

No body motions
detectedSpecification

External dimensions

80 x 80 x 23 mm

Incorporated functions

UWB transmitter and receiver circuit, antenna,
clocking device

Conforming standard

IEEE802.15.4z

CPU core

32 bit ARM Cortex M33 CPU

Memory area

768 kB flash and 128 kB SRAM

Power supply voltage

12 V

Operating temperature range-40 to +105℃

Applications

The UWB unit can be easily installed later in a car.

Child presence can be detected by the UWB ranging communication ① and the radar function ②installed in the simple system configuration.

UWB② The UWB radar function detects
body motions on a rear seat

① The UWB ranging communication detects
a car owner (smartphone) getting off the car

15:03

StatusConnected

Date and time
Message③ The presence of a child is informed
the car owner (smartphone)

A child may
be left in thecar