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Title:
METHOD AND SYSTEM FOR DETECTION OF THE USE CONDITION OF ONE OR SEVERAL SEATS
Document Type and Number:
WIPO Patent Application WO/2019/201741
Kind Code:
A1
Abstract:
A method and a system for detecting the state of use of one or several seats (41) in a transport vehicle. Each seat is equipped with at least two sensors (Ca,Cb), one sensor (Ca) being located at the upperside of the seat (41), and the other sensor (Cb) being located at the underside of the seat (41). According to the invention the capacity of the upper sensor (Ca) is measured together with the capacity of the lower sensor (Cb). By means of these associated capacity measurements is it possible to determine the use of the seat (41), e.g. whether a person is sitting on the seat or whether there is only a newspaper on the seat.

Inventors:
OLRIK, Jakob Christian (Kongestien 81, 2830 Virum, 2830, DK)
VAN PRUISSEN, Elisabeth Gabriella (Pascalerf 2, 5014 EV Tilburg, 5014, NL)
Application Number:
EP2019/059281
Publication Date:
October 24, 2019
Filing Date:
April 11, 2019
Export Citation:
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Assignee:
ATTENSYS.IO GMBH (Dircksenstra├če 40, Berlin, 10178, DE)
International Classes:
H03K17/955; B60N2/00; B60N2/70
Foreign References:
US20150168469A12015-06-18
US20150168469A12015-06-18
Other References:
HANBYUL JIN ET AL: "Stretchable Dual-Capacitor Multi-Sensor for Touch-Curvature-Pressure-Strain Sensing", SCIENTIFIC REPORTS, vol. 7, no. 1, 7 September 2017 (2017-09-07), XP055598165, DOI: 10.1038/s41598-017-11217-w
YI-TA WANG ET AL: "The Fringe-Capacitance of Etching Holes for CMOS-MEMS", MICROMACHINES, vol. 6, no. 11, 28 October 2015 (2015-10-28), pages 1617 - 1628, XP055598166, DOI: 10.3390/mi6111445
Attorney, Agent or Firm:
NORDIC PATENT SERVICE A/S (Bredgade 30, Copenhagen K, DK-1260, DK)
Download PDF:
Claims:
CLAIMS

1. A method for detecting the state of use of a seat (41) in e.g. a transport vehicle, wherein the seat is equipped at least two capacitive sensors (Ca,Cb), characterized in that one sensor (Ca) is located at the upper side of the seat and the other sensor (Cb) is located at the underside of the seat (41), and that the capacity of the upper sensor (Ca) is measured together with the capacity of the lower sensor (Cb).

2. A method according to claim 1, characterized in that each capacitive sensor comprises two layers of mutually separated conductive foils (42,43).

3. A method according to claim 2, characterized in that the distance between the foils (42,43) is approximately 0,15 mm.

4. A method according to claim 2 or 3, characterized in that each of the

conductive foils (42,43) has holes (42a, 43a), the holes being arranged in such a way that the holes in one foil (42) are offset in relation to the holes in the holes the other foil (43).

5. A method according to any of the claims 2-4, characterized in that the holes (42a, 43a) are circular and have a diameter of about 46 mm.

6. A method according to claim 5, characterized in that the center distance between the holes (42a, 43a) is approximately 57 mm.

7. A method according to one or several of the preceding claims, characterized in that the capacity of each sensor is measured by means of a Hf signal of 3.3 to 10 MHz.

8. A method according one or several of the preceding claims, characterized in that the capacity of the upper sensor (Ca) together with the capacity of the lower sensor (Cb) by a pattern recognition system is used to indicate the state of use of each seat (41).

9. A system for carrying out the method according to one or more of the

preceding claims.

AMENDED CLAIMS

received by the International Bureau

on 09 August 2019 (09.08.2019)

1. A method for detecting the state of use of a seat (41) in f. inst. a transport vehicle, wherein the seat is equipped with at least two capacitive sensors (Ca,Cb) characterized in that one sensor (Ca) is located at the upper side of the seat and the other sensor (Cb) is located at the underside of the seat (41), and that the capacity of the upper sensor (Ca) is measured together with the capacity of the lower sensor (Cb), wherein each of the capacitive sensors comprises two layers of mutually separated conductive foils (42,43) and each of the conductive foils (42,43) has holes (42a, 43a) arranged in such a way that the holes in one foil (42) are offset in relation to the holes in the other foil (43).

2. A method according to claim 1, characterized in that the distance between the foils (42,43) is

approximately 0,15 mm.

3. A method according to claim 1 or 2, characterized in that the holes (42a, 43a) are circular and have diameter of about 46 mm.

4. A method according to claim 3, characterized in that the center distance between the holes

(42a, 43a) is approximately 57 mm.

5. A method according to any of the preceding claims, characterized in that the capacity of each

sensor is measured by means of a HF signal of 3.3 to 10 MHz.

6. A method according to any of the preceding claims, characterized in that the capacity of the upper sensor (Ca) together with the capacity of the lower sensor (Cb) by means of a pattern recognition system is used to indicate the state of use of each seat (41).

7. A system for carrying out the method according to one or more of the preceding claims.

Description:
Method and system for detection of the use condition of one or several seats

Field of the Invention

The invention is related to a method for detection of the use condition of a seat e.g. in a transport vehicle, where the seat is equipped at least two capacitive sensors.

Background Art

US 2015/0168469 describes a method and an apparatus for detection of the use condition of a seat. The apparatus comprises a reference capacitor with reference to a first reference potential, an electrode integrated in a seat sensor with a capacity in relation to the first potential and a parasitic capacity with reference to another potential. This apparatus makes it possible to detect and distinguish between a person, a handbag or only water on the seat. However, such a detection requires a number of process steps as several contacts in the apparatus have to be activated in a predetermined sequence.

Description of the Invention

The object of the invention is to illustrate how the detection of the use condition of the seat can be simplified, and this object is according to the invention obtained by placing one sensor at the upper side of the seat and another sensor at the underside and by measuring the capacity of the upper sensor together with the capacity of the lower sensor. These associated capacity measurements make it possible to determine the use condition of the seat e.g. if a person is placed on the seat or if only a newspaper is placed on the seat.

Each of the capacitive sensors may according to the invention consist of two layers of conductive foil separated by a distance of about 0,15 mm.

Further may according to the invention each of the conductive foils have holes, the foils being placed in such a way that the holes in one foil are offset in relation to the holes in the second foil. Thereby parasitic capacities are obtained due to the stray fields at the edges of each of the holes (edge effect).

According to the invention the holes may be substantially circular and have a diameter of about 46 mm and the center distance between the holes may be about 57 mm.

The capacity of each sensor may according to the invention be measured by means of a Hf signal with a frequency of about 3,3 to 10 MHz. Finally according to the invention the capacity of the upper sensor together with the capacity of the lover sensor may be used to indicate the use condition of each seat.

Brief description of the Invention

The invention will be explained in more detail in the following with reference to the drawings in which

Fig 1 shows a chair seat equipped with capacitive sensors for exercising the method according to the invention for detecting the use condition of the seat

Fig 2 electrode plates of one of the capacitive sensors,

Fig 3 a block diagram of a portion of the electrical circuit for detecting the use condition of use,

Fig 4 a block diagram of the entire electrical circuit for detecting the condition of use,

Fig 5a, 5b, 6a and 6b illustrate a more detailed view of each block in the block diagram, as Fig 6a shows a SerielRS-485 to UART and Fig 6b shows a microcontroller,

Fig 7a and 7b a flow chart of the associated program,

Fig 8a and 8b illustrate how the relationships between the capacities of the two sensors depend on the specific condition of use and

Fig 9 a sensor reading as a function of the number of ml water on a seat.

Best modes for carrying out the Invention

The seat 41 illustrated in Fig 1 is equipped with a system according to the invention for detecting the condition of use of the seat. The system comprises two capacitive sensors Ca,Cb, one sensor being located at the upper side of the seat 41 and the other sensor Cb being located at or close to the underside of the seat 41. Each of the capacitive sensors consists of two layers of conductive foils 42,43, conf Figs 2a and 2b, in form of metal coated fabric, the distance between the foils being

approximately 0,15 mm. Each of the conductive foils 42,43 covers substantially the whole surface of the seat or only a portion thereof. Each of the conductive foils 42,43 has a great number of holes 42a, 43a, typically circular holes. In a specific embodiment the circular holes have a diameter of approximately 46mm and the center distance between the holes is e.g. 57 mm. However other diameters and other center distances can also be used. The holes in the foils 42,43 are preferably offset from each other. The purpose of these holes is to provide parasitic or stray capacities. During exercise of the invention a Hf signal is applied to each of the capacitive sensors Ca,Cb. The signal frequency is either 3,3 MHz or 10 MHz although other frequencies also can be used. By means of this signal the capacity of the capacitve sensors Ca,Cb can be measured by measuring the ratio between the voltage and the current through each of the sensors. A block diagram of the associated electrical circuit is illustrated in Figs 3 and 4.

The relevant information is the relation between the two capacities as this relation can be used to determine the use condition of the seat 41. Fig 8a and 8b illustrates examples thereof in a specific embodiment of the capacitive sensors. If the upper capacity is 120 pF and the lower capacity is 80 pF, it indicates a person sitting on the seat 41. The reason is that both the parasitic capacities of both the upper and the lower sensor is influenced by the person. If on the other hand there is only a bag on the seat 41 both capacities will be only approximately 15 pF. If there is a lighter object such as a newspaper on the seat the capacities will be less than 15 pF but still measurable.

The electrical circuit for detecting the condition of use of the seat 41 is illustrated in Figs 3 and 4. It consists of a Tl (Texas Instruments) FDC 2114 34 which is a 4 channel capacitive sensor. Fig 3 shows how FDC 2114 34 through a cable, a LC circuit and a noise filter is connected to the capacities Ca and Cb to be measured. FDC 2114 34 is via an i2c bus connected to an Atmel SAMD09 microcontroller 33, conf Fig 4. This microcontroller 33 is connected to an UART/RS485 converting data from serial to balanced form via the communication standard RS 485, said UART being connected to a Host Computer 31. The Host computer 31 retrieves readings from the sensors Ca,Cb and store and processes the said data by using a classification and pattern recognition algorithm classifying the said data and storing them in a data base.

Fig 5a and 5b show a detailed diagram of FDC2114 34 with an EMI protection and a noise filter.

Fig 6a and 6b illustrate the UART converter converting data from serial to balanced serial form. Furthermore the microcontroller 33 connected to FDC2114 34 via bus i2c, is also illustrated.

Fig 7a and 7b illustrate a flow chart of the program for controlling FDC2114 34, Serial RS-485 to UART and the microcontroller 33 and the Host Computer 31.

In block 2 the system is initiated. In block 3 UART converter is configured with interrupt. In block a General Purpose in/out is set up. In block 5 a set-up of serial communication. In block 6 a printout of the set up for FDC2114_1. In block 7 a printout of the set up for FDC2114_2. In block 8 a RC timer is set up. In block 9 an activation of the UART interrupt. In block 10 a reading of FDC2114_1 sensor values (serial communication). In block 11 an update of memory register data of FDC_2 sensor values. In block 13, an update of memory register data and status bit.

The blocks 1-13 thus serves to collect data for measurement values, 1-9 for microcontroller set up and 10-13 for data collection.

At appropriate intervals controlled by the RTC timer the collected data is passed to the Host computer 31 reading the data at 14. At 15 it is examined whether this is the first byte of a packet. If this is the case, the system jumps to block 17, where it is checked whether the input corresponds to a node ID. If this is the case, a Modbus buffer is reset in block 18. Subsequently the Modbus buffer and the timer are updated. When the last byte is read, block 22 asks if CRC in the input packet is OK, in which case the desired hold data is derived from the input packet in block 22, and if the hold register is supported, the hold register is stored in an output buffer (at 25). Subsequently (in 26) CRC is calculated for the output buffer and added to the buffer. Subsequently the Modbus output buffer is sent to the Host computer 31, where by means of a pattern recognition algorithm a determination is performed as to the condition of each seat 41.

A more detailed description of the flow charts is described in the following.

General system initialization is within the frames of the atmel software. Included drivers are "Port- GP1D control driver", "RTC- Rent Time Counter Driver", "RTC-Rent Time Counter Driver", "SERCOM 12C- Master Mode Driver" and "SERCOM USART- Seriel communication driver" as well as two standard drivers "General board support" and "SYSTEM-Core System Driver". These drivers enable an internal 8 MHz clock generator and prepare the various hardware interfaces for starting the operation.

The serial interface SERCOM 1 (3) is configured as an UART to communicate with the Host computer 31 with activated interrupts. The hardware interface is routed to the RXTX terminals as shown in Fig 6b. The implementation follows the flow as described in "Atmel-4218-SAM-Serial-USART-Sercom-USART Driver Application Note AT03256". Interrupt is configured to trigger when a complete data byte is received at the interface- interrupt is activated later when the whole set-up is completed.

GPIOs (4) (general purpose in/out) is a set-up described in "Atmel-42113-SAM-Port- Driver Application Note-AT03248". The system has five GPIOs-2 inputs and 4 outputs. INTB1 and INTB2 are output from the FDC 2114 sensor chip 34, which indicates that new data is available- data from the sensor is retrieved and INTB1 and INTB2 are configured but not used.

FDC_SD (shut down) controls the power supply state of the FDC 2114 sensor chip 34 i.e. shutdown mode vs operating mode. Data is constantly sampled and the sensors are constantly in operation. SWCLK_PTXEN and SWDI0_NRXEN control the direction of transmission of data from UART to RS-485 converter (MAX 13430 EE UB plus), conf Fig 6a. The last GPIO controls an on board LED which will flash in case of an error.

The serial interface SERCOMO (5) located in 33 is configured as an i2c master to communicate with the FDC 2114 chip "Atmel-42117-SAM-i2c-BusDriver-Sercom- i2c_Application Note AT03250". The SDA SCL signals are routed as shown in the diagram.

With the i2c master interface initialized, each FDC 2114 (6,/) sensor chip is set up with all 4 channels active and 50 samples/sec/channel. The register overview appears from the FDC 2114 data sheet thhp://www.ti.com/lit/des/svmlink/fdc2212- gl-pdf.

RTC 8 is set up as a background counter as described in "Atmel-42111-SAM-RTC- Count_Application note_AT03249". A comparator is set to flake after a

predetermined time. This is necessary to be able to follow the transmission outlets for the RS-485 interface and packet delays as required according to the MODBUS RTU protocol.

UART interrupt 9 is activated so as to start triggering each time a byte is received at the UART/RS-485 interface" Atmel-42118-SAM-Serial-USART-Sericom-USART-Driver Application Note_AT03256". SWCLK_PIXEN and SWD10_NRXEN are set so that the RS-485 transceiver is in receive mode.

Main loop (10,11,12,13,29).

The main loop (29) will constantly sample data from the FDC2114 chips. At appearance of an UART interrupt the program will branch out to decode the received UART data. The sensor data from the first FDC chip (IC2) is read via the i2C master interface. FDC1 has the address UX2B as the address pin at the chip is pulled high. All 4 channels (CH0-CH3) are read. The data from the first FDC chip (11) is stored in HOST 31.

The sensor data from the second FDC 2114 chip (IC1) (12) is stored via the i2C master interface. FDC2 has the address OX2A as the address pin at the chip is pulled low. Only the last two channels (CH2-CH3) are read as the two first are interrupted. The data from the second FDC chip (13) is stored in the register 31.

Interrupt of the main loop (29) when interrupt is triggered from UART (14), the main loop 29 is interrupted and a number of operations are performed. The system supports one of the Modbus functions and a number of operations are performed. The system supports one the Modbus functions i. e. read hold records (http://www.modbus.org/docs/Modbus Application Protocol Vllb3.pdf). An input packet for reading the hold register is 8 bit long and has the format according to the said link.

Data requests for packet format (byte by byte)- reads the hold records.

Slave address Function Startrad Hi Startadr Lo Number of registers Hi Number of registers Lo CRC Lo CRC Hi

In the interrupt routine, a counter keeps an eye on the number of bytes received in the packet (15.20). If the received byte is the first in a packet (15), the system checks whether the value of the packet is equal to the address assigned to the node ID (17). If this is the case, the input buffer 19 is reset (18) and the byte is stored in the input buffer (19). An expiration timer running on the RTC is also reset. If the value of the byte is not equal to node ID (17), the system will interrupt the interrupt routine (21) and return to the main loop of the program (29), where it was interrupted between 10,11,12,13.

If the byte is not the first in a packet (15), the system will check whether the time out of the timer has occurred and if this is the case, the byte will be stored in the input buffer for later use and the expiration timer is reset again. If time out has occurred, the system will check if the incoming byte is equal to node ID (17), being the first byte in a packet, and the input buffer will be reset as described above. If both time out has occurred and the value of the byte is not equal to node ID (17), the system will leave the interrupt routine (21) and return to the main loop (29), where it was interrupted between 10,11,12,13.

If the last byte in a packet i.e. byte 8 is received (22), the input packet will be decoded. First the CRC-16 of the input packet is calculated and compared to the received. If the CRC does not match, the input buffer and the timer are reset (28) and the system interrupts (21) the interrupt routine and returns to the program. If the CRC matches, the host registers (22) requested by the host are derived (23) from the input packet. The system controls the derived registers (24,25). If available, an output pack of CRC is prepared (26) according to the MODBUS formats shown in the following (27).

Data response packet format (byte view)

Slave Function Data byte Data Hi Data Lo CRC Lo CRC Hi Address Count n x number of registers (2x number of registers) If the desired hold records are not available (24), the MODBUS buffer and the timer are reset (28), the system leaves the interrupt routine (21) and returns to the main loop (29).

With the valid output packet (27), the system waits a period corresponding to 3.5 characters as defined in the MODBUS protocol and activates the RS-485 transmitter before the output packet via the UART SERCOM1 interface is sent to the Host computer 31. RS-485 is reset in the receive mode after the transmission and the output buffer is reset in the receive mode after the transmission and the input buffer, the output buffer and the timer are reset (28) before the system finally interrupts the interrupt routine (21) and returns to the main loop of the program (29).

An example of an input and an output pack is shown in the following Example of a package request and a response from CCU 31 to Node 33 (Request) 0x01 0x03 0x00 0x02 0x00 0x03 0x4A 0x0 B

The data request packet is an example of a reading of the three hold registers including te sensor data in node 33 i. e.

Slave address 1

Function code 03-read hold registers Start address 40003 (0x0002)

Number of registers 3

Resulting crc 0xB4A

From node 33 to CCU 31 (answer)

0x01 0x03 0x06 OxlC OxFA 0x55 OxDE 0x4D 0x5A

That is, the answers from the node with address 0x01 of the function type 03

Reg 0x0002 data OxlClC

Reg 0x0003 data: OxAFFA

Reg =x0004 data: 0x550E

CRC: 0x5A4D

A pattern recognition algorithm in the computer may from the pattern or the associated values of measured capacities indicate the state of use of the seat 41. The circuit is very sensitive and selective, being able to distinguish between newspapers, bottles, smart phones, labs, bags and human beings. The circuit is even so sensitive that it is able to distinguish between a man and a female. This has been proven in several trials. Furthermore, it has been demonstrated that the sensor reading as a function of the number of ml of water on a seat is substantially linear, conf Fig 9, illustrating an embodiment in which the distance between the two conductive layers 42,43 in the upper sensor Ca is approximately 2 mm.

The method and the circuit according to the invention is particularly suitable for transport vehicles such as trains, busses and aircrafts, being able to from a central position to locate and monitor the number of vacant seats in the vehicle.

Furthermore you can quickly get an overview of forgotten people and you can even see what is left on the seat 41. This saves time for the staff. This is of particular importance in trains and aircrafts where the time factor is crucial. Furthermore a better quality control is made possible.

The method and the circuit according to the invention may be varied in many ways without departing from the idea of the invention.