60 GHz Radar Sensor for Seat Occupancy Detection
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Solution Overview
Problem
Current seat occupation detection systems, primarily using pressure sensors, struggle to differentiate between humans and objects, leading to safety concerns such as unnecessary airbag activation and the risk of heat-related injuries or fatalities, especially for children left in vehicles, and require complex integration with vehicle infrastructure, limiting aftermarket deployment.
Innovation Solution
A mm-wave radar system with high-gain planar antennas operating in the 60 GHz ISM band, utilizing System on Chip technology for analog processing and digital signal processing, allows for accurate detection of heartbeat and breathing dynamics without physical contact, providing a compact, low-cost solution that can function independently and simultaneously across multiple seats without the need for complex infrastructure integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are used for seat occupation detection, then seat occupation can be detected, but the system cannot differentiate between humans and objects
Solution Approach 1:
The system transitions from static weight measurement to dynamic vital sign detection by monitoring heartbeat and breathing patterns. The radar sensor detects micro-movements caused by cardiac and respiratory activities, enabling differentiation between living humans and inanimate objects based on physiological dynamics rather than static weight alone.
Solution Approach 2:
The patent replaces mechanical pressure sensors with electromagnetic radar sensing. Instead of using physical contact-based pressure detection, the system employs mm-wave radar to detect vital signs through non-contact means, substituting mechanical measurement with electromagnetic field-based detection to gain additional information about human presence.
2Reliability
If pressure sensors are integrated in seats, then seat occupation can be detected, but complex integration with vehicle infrastructure is required
Solution Approach 1:
The radar sensor system serves multiple functions beyond seat occupation detection, including vital sign monitoring, human identification, and potential applications for child safety and driver monitoring. This multi-functionality reduces the need for separate specialized sensors and simplifies overall system integration across different vehicle configurations.
Solution Approach 2:
The system extracts the essential detection function from the seat structure itself by using radar sensors that can be positioned independently in the vehicle cabin. Rather than requiring integration into every seat's mechanical structure, the radar system can detect occupants in seatless configurations, extracting the detection capability from the seat infrastructure.
3Object-affected harmful factors
If airbag system is activated based on pressure sensor detection, then safety response is provided, but unnecessary activation may occur when objects are detected
Solution Approach 1:
The system uses dynamic vital sign patterns (heartbeat frequency, breathing rate, and their variations) to distinguish living humans from inanimate objects. By analyzing the temporal dynamics of physiological signals rather than static weight information, the system can accurately determine whether an occupant is alive and human, preventing false airbag activation while ensuring safety when needed.
4Speed
If microwave radar sensor operates at lower frequency (3-10 GHz), then detection range is extended, but measurement precision for vital signs decreases
Solution Approach 1:
The system changes the operating frequency parameter from lower bands (3-10 GHz) to the higher 60 GHz band, optimizing for vital sign detection precision rather than maximum range. The 60 GHz frequency provides better resolution for detecting micro-movements associated with heartbeat and breathing, while the high-gain planar antenna compensates for reduced propagation distance through increased signal directionality and gain.
5Measurement precision
If high-gain planar antenna system is used at 60 GHz, then measurement precision for vital signs is improved, but antenna size increases
Solution Approach 1:
The patent transitions from conventional omnidirectional or broad-beam antennas to high-gain planar antenna arrays that focus energy in specific directions. By introducing spatial dimensionality control through planar geometry and element arrangement, the system achieves high gain and directional precision without proportionally increasing overall system area, as the enhanced directionality compensates for the physical size.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enhances safety by accurately distinguishing between adults, children, and objects, reducing false alarms and heat-related risks, while enabling easy aftermarket installation and reducing assembly costs through its compact and low-power design.
Implementation Method 1
Millimetre-wave radar with integrated front end on silicon, providing analog processing of the mm-wave signal
Implementation Method 2
microwave radar sensor... may be used to detect the vital signs
Data Source
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AI summary
The present invention discloses a mm-wave radar sensor to be deployed in the vehicles for seat occupation detection applications. The key system relevant components are utilization of mm-wave integrated radar, specific planar high-gain antenna radiation pattern, and analyzing of the heartbeat and optionally also respiratory dynamics. The method of operation calculates probability of the seat occupation event regarding: detection of the passenger on the seat, detection of a baby or a child on the seat, detection of the presence of a baby or a child in the vehicle after the driver has left the vehicle, detection of the human or animal presence of intrusion in specific vehicle environment. In case that probability is above a predefined threshold, typically the interaction with vehicle control system is initiated using arbitrary automotive interfaces. Corresponding predefined actions are taken in that case. The predefined actions could be one or combination of the following: audio signal alerts to driver, inside cabin light condition change, engine operation condition change, opening of the windows or corresponding communication using arbitrary wireless means to outside vehicle environment. Optionally, the system is utilizing additional parameters like vehicle cabin temperature and/or timing information about engine stop and driver leaving the car. Preferably, the system is using 60 GHz or 77-79 GHz integrated radar front end working in Doppler operation mode, with 4 x 4 Tx and Rx planar radiation elements, with physical size typically in the range 4 x 2 x 1 cm, or smaller.