Patent Application
20170036541
The present invention relates to a seat occupation sensor and decision making device comprising mm-wave radar with planar high-gain antenna systems, utilizing information extracted from processing of both human heartbeat and breathing dynamics.
There is a strong motivation to deploy the smart seat occupation sensor in the following applications:
The primary motivation to address those problems is related to improving safety aspects by providing new features. Additionally, economic benefits will be introduced, e.g. by avoiding unnecessary air bag activation. Proposed technology offers an alternative to currently commonly used systems integrated in car seats with more features and with lower or same cost.
There is a need to enable differentiation between an object placed on a seat and the human being seating. Seat occupation is currently commonly detected by the pressure sensors integrated in the seat. Current solutions generally cannot easily differentiate between the child, adult, or object placed on a seat. This information may be used for safety belt alarm or air bag activation. Namely, airbag system may be switched on or off depending on whether there is a human or object on a seat. Furthermore, the airbag explosion could be adjusted depending on whether there is a child or an adult present. A child in a rear facing child seat, which is placed on the right front passenger seat, is in danger of being seriously injured if the passenger airbag deploys.
The health or even a life of a child or a disabled person left alone in the vehicle, either intentionally or inadvertently, can be endangered in case the temperature in the vehicle rises. The baby or child could suffocate due to the lack of oxygen in the cabin. On a typical summer day, the temperature inside a parked car can be up to 30° C. higher than the outside temperature. 75% of the temperature rise occurs within 5 minutes of closing the car and leaving it, 90% of the temperature rise occurs within 15 minutes. Dark colored vehicles reach slightly higher temperatures than lighter colored vehicles. The greater the area of glass in a car, the faster is the rise in temperature. Larger cars heat up just as fast as smaller cars. As the temperature rises, children begin to develop heat stress and also to dehydrate. Young children are more sensitive to heat than older children or adults and are at greater risk of heatstroke. There are the mortal cases on infants reported in real world. From 1998 to 2012 in USA, 559 child heatstroke deaths in vehicles, 288 (52 percent) happened after caretakers simply forgot they were there in car.
The state-of-the-art pressure sensors incorporated in the seat require a wired connection to the vehicle infrastructure. Hence, additional system integration efforts are required during manufacturing, in addition to the actual sensor cost. If the seats are not present in a vehicle, e.g. in case second or third row of seats was removed, there is no information about the presence of humans or animals. Ideally the information on human or animal presence should be available regardless of the seat infrastructure.
It was published in different scientific articles that microwave radar sensor, in the frequency range 3-30 GHz, may be used to detect the vital signs. Especially 2.4, 3-10, 24 and 60 GHz vital sign demonstrators have been publicly reported.
The following patents and patent applications published in last several years show the relevance of the topic and the state-of-the-art.
US 20120242492 A1, “Seat occupancy detection and display system”, treats seat occupation by weight detection from sensors integrated in the seat, and further analysis by signal processing.
U.S. Pat. No. 8,115,648 B2, “Seat occupancy sensor”, of IEE and BMW, proposes pressure sensing systems integrated in vehicle seats.
U.S. Pat. No. 6,026,340 A, “Automotive occupant sensor system and method of operation by sensor fusion”, of Robert Bosch GmbH, proposes combined ultrasonic and infrared sensors for seat occupation detection.
WO 2013007540 A1, “Seat heater and capacitive occupancy sensor combination”, of IEE, proposes the combination of seat heating system with capacitive sensors.
EP 2631113 A1, “Seat device and method for disposing seat occupancy sensor used therein”, of Fijukura Ltd, treats specific pressure sensor arrangements.
DE 102011056522 A1, “Industrial truck i.e. forklift, has occupancy sensor and seat belt buckle sensor connected with control unit, where control unit is separate controller for monitoring correct usage of safety belt and separated from vehicle control system”, of Linde Material Handling Gmbh, proposes sensor in safety belts as a means for seat occupancy detection.
WO 2011033360 A1, “Vehicle seat occupancy sensor”, of Toyota, considers pressure sensor arrangements.
WO 2013092946 A1, “Occupancy sensor for occupiable item e.g. seat or bed”, of IEE, introduces thermistor for heat based sensing.
DE 10131080 A1, “Optical seat occupancy sensor networks”, of Daimler Chrysler Ag, introduces optical network for seat occupancy detection.
U.S. Pat. No. 8,013,727 B2, “Device for detecting vehicle seat occupancy”, introduces electrical capacity sensors for seat occupancy.
U.S. Pat. No. 6,445,988 B1, “System for determining the occupancy state of a seat in a vehicle and controlling a component based thereon” relates to utilization of neural networks and different transducers.
U.S. Pat. No. 6,736,231 B2, “Vehicular occupant motion detection system using radar” introduces ultrasonic radar approach for determining seat occupancy by detecting the vital signs information. Its “radar” based system has two physically separated receivers of reflected ultrasound signals, and two units for further processing.
U.S. Pat. No. 6,104,293 A, “Warning system for detecting presence of a child in an infant seat” is based on warning to be issued by stopping the ignition of the car and intelligence in the infant seats.
DE 60125353 T2, “Seat occupancy recognition system” is utilizing safety belts as an occupancy sensor.
This invention proposed apparatus 100 and method of operation for seat occupancy detection, and initialization of the related actions, improving safety.
The key system relevant components of the proposed apparatus 100 are:
Millimeter-wave front end preferably operates in 60 GHz ISM Band. The usage of the 77-79 GHz mm-wave frequency bands or higher mm-wave ISM bands is also proposed. The Rx and Tx antennas preferably have 4×4 elements, to explore the tradeoff between the size of the antenna, having impacts on the system cost and its integration in the vehicle environment, and obtaining the narrow antenna beam. The narrow antenna beam, associated with explicit high-gain antenna approach is essential part of the system, providing limited possibility that the biometric data, i.e. heartbeats or respirations, from the persons in the vicinity, but not on the seat. This is one of the essential innovative approaches, because it dramatically decreases the complexity of the digital processing, providing simple and low-cost apparatus. This is also an essential system-related factor, which imposes the use of mm-wave signals for seat occupation detection applications, as opposed to the state-of-the-art wireless technologies utilizing ultrasound system, such as U.S. Pat. No. 6,736,231.
Using mm-wave frequency band, preferably the 60 GHz ISM band, allows several important system related advantages compared to ultrasound approach proposed in U.S. Pat. No. 6,736,231:
It would be very difficult for the system proposed in U.S. Pat. No. 6,736,231 to operate in the realistic scenario, with each of the seats monitored with a separate TX and a pair of RX parts. The TX part of one seat would interact with RX parts of other seats. Thus, they could work only if they are coordinated, meaning that central vehicle system activates seat detection for one seat at a time, which increases the system handling dramatically. Otherwise, the signal processing would be even more complex and would require much more resources. Proposed innovative system may work independently and simultaneously, with frequency reuse for all sensors due to the high directivity of the RX and TX antenna.
Due to the propagation of the ultrasound, it is very likely that the system proposed in U.S. Pat. No. 6,736,231 would “pick-up” vital signals from persons from neighboring seats. To overcome this problem, huge processing efforts are needed. Our proposed system can be easily used due to the narrow beam radiation pattern “looking” only at a single seat.
The proposed approach of U.S. Pat. No. 6,736,231 has a system drawback of difficult deployment in the aftermarket mode, requiring a lot of installation efforts, especially for integrating hardware in the vehicle cabin environment, in contrast to proposed approach where a compact module of 4×2×1 cm may be utilized, potentially without any connection to the vehicle infrastructure. Due to relaxed processing requirements, only small digital hardware is required, providing low-power operation and low dissipation.
Unlike the ultrasound, mm-wave frequency band signals do not penetrate the human skin.
Present invention has innovative approach of integrating complete RF functionalities of the mm-wave radar (30-300 GHz) within a system-on-chip, including complete mm-wave frequency synthesis, fabricated in standard silicon process. Digital signal processing is using single digital processing HW for simultaneous processing of both heartbeat and respiratory signals.
The proposed system analyses both heartbeat and breathing simultaneously, thereby dramatically increasing the accuracy of seat occupation detection and decreasing the probability of the false alarm. Only the heartbeat analysis may be considered as sufficient for some seat occupation detection applications in order to reduce the system complexity.
The proposed apparatus has significant advantages compared to the state-of-the-art, in at least of one of the following features:
The proposed system may function with several meters distance between the human and the apparatus, depending on the antenna arrangement, transmit power, and receiver sensitivity. The transmit power is, however, reduced to the minimum needed, for the reasons of having minimum power consumption, minimal thermal dissipation, and minimum reflection clutters, which will further simplify digital processing algorithms and further reduce the power consumption and thermal dissipation. The digital part typically includes CAN and/or LIN interface allowing easy connection to the vehicle infrastructure. The means of short range wireless connection to the vehicle system 63 is optional and suited for the aftermarket usage. In aftermarket mode the proposed apparatus may have integrated audio and/or visual indicators.
Apparatus 100 could be also realized with one high gain planar antenna and isolator functionality. This may reduce the size of the system but in the same time increase the technical requirements on isolator functionality, which is difficult to release in the low cost and miniature manner.
Instead of the down conversion mixer in the integrated mm-wave chip functionality 10, the IQ demodulator may be integrated, providing some extra features in the digital signal processing.
Apparatus 100 is preferably integrated in the vehicle, having Line-of-Sight (LOS), i.e. no obstacles, between the system and the human body, as shown in the
The crucial block of the proposed apparatus 100 is the Integrated mm-wave front end, -System on Chip- 10. It contains the complete RF functionality, and includes power amplifier functionality attached to the antenna system 22, low noise amplifier attached to antenna system 21, integrated PLL, used both for up-conversion in transmit and down-conversion in receive, one analog pre filtered an amplified signal or providing two analog pre-filtered and amplified signals as IQ outputs to A/D conversion functionality 30. The entity 10 has test functionality, voltage regulation, and digital interface to the Controlling functionality 41, which is a part of the Digital Processing functionality 40. More detailed structure of the integrated front end 10 is given in
Digital processing functionality 40 may be realized by the plurality of technologies, such as: advanced CPUs, FPGAs, advanced μC, DSP, or ASIC, or their combinations, where the digital processing may be performed by “soft” approach or by hard-wired approach or by their combination. Preferably functionalities 60 and 40 are integrated on a simple ASIC, having CPU on one digital SOC. Digital processing functionality 40 includes functionalities 41, 421-429 and 70-71 as described in
Comparison thresholds may be predefined or statistically calculated based on the stored data.
Time information entity 717 is providing optional additional information to entity 720 including:
Optional entity 719 is providing information form the external cabin gas sensor to entity 720, preferably including CO2 concentration. Optional entity 718 provides information of the vehicle cabin temperature to entity 720. This information may be provided from external sensors embedded in vehicle provided to apparatus 100 through entity 60.
Seat occupation event calculation entity 720 calculates seat occupation score based on a weighted sum of the following information set, with possible zero weights in case corresponding optional blocks are not present:
The weighting factors are predefined or determined based on the information set, predefined values and behavior statistics. If the score is above the threshold, the different seat occupation events are detected. Based on the score value, the seat occupation events are determined. This information is communicated to the entity 71. Based on this information, the entity 71 is initiating predefined actions using entity 60 and/or entity 50 where optional audio and optional visual indication/alerting capabilities are included.
Predefined seat occupation events are:
If the apparatus detects the abrupt stop of the heartbeat confirmed with the cease of respiratory activity, alerts to the driver are initiated. In case the driver does not respond, emergency condition is confirmed and emergency actions are initiated. Emergency actions may include appropriate engine and brake systems control, and/or emergency calls.
In
Supporting circuitry 50 as a part of the apparatus 100 may include loudspeaker and/or light source functionality having plurality of possible realizations. This feature would allow apparatus 100 to be independent of the vehicle infrastructure by initializing appropriate audio and/or visual warnings and/or indications. These options are useful for all types of the aftermarket applications, where the apparatus 100 is assembled in vehicles after production.
Alternatively instead of using two high gain antennas one for Tx 22 and one for Rx 21, the proposed system may be realized by one high gain antenna for both Rx and Tx functionality, 24 like in
The usage of the IQ demodulator instead of signal mixer in entity 10, would provide the two analog baseband down converted quadrature signals to the entity 30. Having two signals in the signal processing path additional information about phase changes between two signal may be used. This may increase the accuracy in the digital signal processing and some redundancy, by the expense of the more chip size of entity 10 and more processing efforts of the entity 40. The method of operation may use the straight forward information obtained from the one down conversion chain from I or from Q chain, and do not process the information from other chain, as long there is no need in more accurate information extraction. The existence of the both chains, with 90 degrees moved zero crossings, may have practical advantages. By evaluating the phase changes of the IQ signals, with the typical accuracy of 1-2 degrees resolution, micro movements of the objects may be evaluated with more accuracy, within one wave length typically in μm region. This may increase the capability of the frequency extraction.
| Number | Date | Country | Kind |
|---|---|---|---|
| P-2014/0182 | Apr 2014 | RS | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/RS2015/000009 | 4/15/2015 | WO | 00 |
