Pressure sensing cushion for driver fatigue detection and detection method thereof

Abstract

The invention relates to the field of seat cushions, in particular to a pressure sensing seat cushion for driver fatigue detection and a detection method thereof, and the pressure sensing seat cushion for driver fatigue detection comprises a seat cushion body; the eight pressure fabric sensors are arranged on the cushion body, each pressure fabric sensor comprises a pressure-sensitive fabric and two conductive fabrics, the pressure-sensitive fabric is located between the two conductive fabrics, the two conductive fabrics are fixed on the conductive fabrics, and the conductive fabric close to the upper side of the cushion body is fixed on the cushion body; the conductive fabric close to the cushion body is arranged to be connected with one end of a signal line, and the other end of the signal line is connected with the processing unit; and an external terminal. According to the invention, the sitting posture of the user can be monitored and fed back in real time by effectively utilizing the structural configuration of the sitting posture feedback device.

Description

Technical Field

[0001] The present application relates to the field of seat cushions, and more particularly to a pressure-sensing seat cushion for driver fatigue detection and a detection method thereof. Background Art

[0002] Long-time driving can easily lead to states such as fatigue, drowsiness, and distraction of the driver. The detection technologies for driving fatigue mainly include physiological monitoring methods, behavior monitoring methods, and electroencephalogram monitoring methods. The physiological monitoring method determines the fatigue state by monitoring physiological indicators such as the driver's heart rate and breathing rate; the behavior monitoring method evaluates by analyzing the driver's eye movement, facial expression, yawning frequency, driving mode of the vehicle, etc.; the electroencephalogram monitoring method determines the fatigue degree in real time by monitoring the changes in brain waves. These monitoring methods usually require the driver to wear additional sensors during driving, which affects the experience and comfort in the long-time driving environment.

[0003] Posture detection is an effective way for driving fatigue detection. The driver may change their sitting posture due to behaviors such as inattention, using a mobile phone, eating, or dozing off. By monitoring the changes in the driver's sitting posture, the system can detect abnormal postures, such as signs of fatigue or distraction like head drooping, forward leaning, backward leaning, and loose shoulders, and issue a warning in time to remind the driver to concentrate and take a rest, avoiding traffic accidents caused by fatigue driving.

[0004] The existing posture detection technologies mainly rely on basic hardware such as accelerometers, gyroscopes, and cameras to collect posture data. In order to integrate these electronic hardware, posture detection products need to wear additional devices, such as smart belts, smart vests, etc. These devices may affect the comfort and convenience of users, especially during long-term use. In addition, the existing posture monitoring products are usually relatively expensive, making it difficult for most consumers to afford, which seriously affects their popularity. At the same time, most posture detection products can only provide post-event analysis and lack a real-time feedback mechanism. Moreover, the rise of smart textiles makes it possible to integrate technologies such as computing, sensors, and actuators into the textile itself to realize a new generation of monitoring and response devices. This patent proposes to use smart textile technology to achieve real-time monitoring and feedback of the user's sitting posture. Summary of the Invention

[0005] The main purpose of the present application is to provide a pressure-sensing seat cushion for driver fatigue detection. Among them, the pressure-sensing seat cushion for driver fatigue detection can effectively utilize its own structural configuration to achieve portable detection, and compared with traditional posture detection settings, the present invention is more convenient to carry.

[0006] Another object of the present application is to provide a pressure sensing seat cushion for driver fatigue detection. The pressure sensing seat cushion for driver fatigue detection includes a seat cushion body; eight pressure fabric sensors disposed on the seat cushion body, each of the pressure fabric sensors includes a pressure-sensitive fabric and two conductive fabrics, the pressure-sensitive fabric is located between the two conductive fabrics, and the two conductive fabrics are both fixed on the conductive fabric, and the conductive fabric close to the upper side of the seat cushion body is fixed on the seat cushion body; a processing unit, the conductive fabric close to the seat cushion body is arranged to be connected to one end of a signal line, the other end of the signal line is connected to the processing unit, wherein the front side of the seat cushion body has an arc-shaped embedding groove, the processing unit is arranged in the arc-shaped embedding groove, and in addition, the conductive fabric far from the seat cushion body is arranged to be connected to one end of a ground wire, the other end of the ground wire is connected to the processing unit; and an external terminal, the processing unit is connected to the external terminal, wherein the processing unit includes a PCB circuit board, and the PCB circuit board is provided with an embedded single-chip microcomputer for analyzing pressure signals and transmitting data to the external terminal. The advantage of the present invention is that it can be seamlessly integrated with the upper layer fabric of the seat cover, and the driver does not need to wear additional equipment, which greatly improves the comfort and convenience of wearing. The sensing seat cushion is light, replaceable and machine washable, which improves the user's acceptance of the monitoring product. When the driver needs to change the monitoring environment, only the seat cushion needs to be moved, rather than the seat, which is applicable to fatigue driving monitoring in multiple scenarios. In addition, through the sensor array distributed in the fabric, the intelligent seat cover can real-time monitor the pressure distribution between the human body and the seat.

[0007] Another object of the present application is to provide a pressure sensing seat cushion for driver fatigue detection. The pressure sensing seat cushion for driver fatigue detection has a simple structure and convenient operation, does not involve complex manufacturing processes and expensive materials, has high economy, and is easy to promote and use.

[0008] In order to achieve the above at least one invention object, the present application provides a pressure sensing seat cushion for driver fatigue detection, wherein the pressure sensing seat cushion for driver fatigue detection includes:

[0009] a seat cushion body;

[0010] Eight pressure fabric sensors disposed on the seat cushion body, each of the pressure fabric sensors includes a pressure-sensitive fabric and two conductive fabrics, the pressure-sensitive fabric is located between the two conductive fabrics, and the two conductive fabrics are both fixed on the conductive fabric, and the conductive fabric close to the upper side of the seat cushion body is fixed on the seat cushion body;

[0011] A processing unit, the conductive fabric near the seat cushion body is arranged to be connected to one end of a signal line, and the other end of the signal line is connected to the processing unit. Wherein, the front side of the seat cushion body has an arc-shaped embedding groove, and the processing unit is arranged in the arc-shaped embedding groove. In addition, the conductive fabric far from the seat cushion body is arranged to be connected to one end of a ground wire, and the other end of the ground wire is connected to the processing unit; and

[0012] An external terminal, the processing unit is connected to the external terminal. Wherein, the processing unit includes a PCB circuit board, and the PCB circuit board is provided with an embedded single-chip microcomputer for analyzing pressure signals and transmitting data to the external terminal.

[0013] In one or more embodiments of the present application, the pressure-sensitive fabric is nylon fiber infiltrated with polypyrrole, and the conductive fabric is a carbon cloth woven from carbon fiber.

[0014] In one or more embodiments of the present application, the size of the pressure-sensitive fabric can be implemented as 6×4 cm, and the size of the conductive fabric can be implemented as 5×3 cm. The conductive fabric and the pressure-sensitive fabric are sewn with non-conductive cotton threads to form a single pressure sensing electrode.

[0015] To achieve the above at least one invention purpose, the present application provides a detection method for a pressure sensing seat cushion for driver fatigue detection. The detection method includes:

[0016] S1: Set the seat cushion body on the driver's seat. At the same time, the PCB circuit board integrates a wireless module, and a person sits on the seat cushion body to collect the distribution of sitting posture pressure data in advance. By collecting different driving postures of an individual during driving, record and calculate the standard deviation function of the individual, and transmit the data to the external terminal;

[0017] S2: The 8 pressure fabric sensors are classified in pairs of two to form four detection areas A, B, C, and D. At the same time, the PCB circuit board calculates the average pressure values of 4 pairs of electrodes, and calculates the discrete values of each pair of electrodes through the standard deviation function to determine whether there is an incorrect posture.

[0018] In one or more embodiments of the present application, the interval between the A detection area and the B detection area is 26 mm.

[0019] In one or more embodiments of the present application, the A detection area includes an A1 sensor and an A2 sensor, the distance between the A1 sensor and the A2 sensor is implemented as 15 mm, and the B detection area includes a B1 sensor and a B2 sensor, and the distance between the B1 sensor and the B2 sensor is implemented as 15 mm.

[0020] In one or more embodiments of the present application, the C detection area includes a C1 sensor and a C2 sensor, and the D detection area includes a D1 sensor and a D2 sensor. The C1 sensor is located directly below the A1 sensor with a spacing of 41 mm. The C2 sensor is located directly below the A2 sensor, and the spacing between the C2 sensor and the C1 sensor is 37 mm. Similarly, the D1 sensor is located directly below the B1 sensor with a spacing of 41 mm, and the D2 sensor is located directly below the C2 sensor, and the spacing between the D2 sensor and the D1 sensor is 37 mm. Description of the Drawings

[0021] These and / or other aspects and advantages of the present application will become clearer and easier to understand from the following detailed description of the embodiments of the present application in conjunction with the drawings, where:

[0022] Figure 1 The structural schematic diagram of the pressure fabric sensor is illustrated.

[0023] Figure 2 The wiring layout schematic diagram of the pressure fabric sensor is illustrated.

[0024] Figure 3 The structural schematic diagram of a pressure sensing seat cushion for driver fatigue detection is illustrated.

[0025] Figure 4 The schematic diagram of the pressure detection area division of a pressure sensing seat cushion for driver fatigue detection is illustrated Figure 1 。

[0026] Figure 5 The schematic diagram of the pressure detection area division of a pressure sensing seat cushion for driver fatigue detection is illustrated Figure 2 。 Detailed Description of the Embodiments

[0027] The terms and words used in the following description and claims are not limited to the literal meanings, but are used by the inventors only to enable a clear and consistent understanding of the present application. Therefore, it is obvious to those skilled in the art that the following description of the various embodiments of the present application is provided only for the purpose of illustration and not for the purpose of limiting the present application as defined by the appended claims and their equivalents.

[0028] It can be understood that the term "a" should be understood as "at least one" or "one or more". That is, in one embodiment, the number of an element can be one, while in other embodiments, the number of the element can be multiple. The term "a" cannot be understood as a limitation on the number.

[0029] Although ordinal numbers such as "first", "second", etc. will be used to describe various components, those components are not limited herein. The term is only used to distinguish one component from another. For example, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component, without departing from the teachings of the inventive concept. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0030] The terms used herein are for the purpose of describing various embodiments only and are not intended to be limiting. As used herein, the singular forms are also intended to include the plural forms unless the context clearly dictates otherwise. Additionally, it will be understood that the terms "comprises" and / or "has" when used in this specification specify the presence of the stated features, numbers, steps, operations, components, elements, or combinations thereof, without precluding the presence or addition of one or more other features, numbers, steps, operations, components, elements, or groups thereof.

[0031] Reference Figures 1 to 5 , according to a preferred embodiment of the present invention, a pressure-sensing seat cushion for driver fatigue detection, it should be noted that the pressure-sensing seat cushion for driver fatigue detection is used for sitting posture detection, specifically for sitting posture detection during automobile driving, that is, a driver may change his sitting posture due to behaviors such as inattention, using a mobile phone, eating, dozing off, etc. By monitoring the sitting posture change of the driver, the seat cushion can detect abnormal postures, such as fatigue or distraction signs such as head drooping, leaning forward, leaning backward, and shoulder relaxation, which lead to sitting posture changes, so as to issue a warning in time to remind the driver to concentrate and take a rest, and avoid traffic accidents caused by fatigue driving.

[0032] Specifically, the pressure-sensing seat cushion for driver fatigue detection includes a seat cushion body 10 and a plurality of pressure fabric sensors 20 provided on the seat cushion body 10. Specifically, the number of the above-mentioned pressure fabric sensors 20 can be implemented as 8, and according to the pressure distribution of the human body and the seat under normal sitting postures, these pressure fabric sensors 20 are arranged at an interval of 8 cm and symmetrically to ensure that the seat cushion can accurately monitor the sitting posture of the user. In addition, each of the pressure fabric sensors 20 includes a pressure-sensitive fabric and two conductive fabrics, the pressure-sensitive fabric is located between the two conductive fabrics, and both of the conductive fabrics are fixed on the conductive fabric, and the conductive fabric close to the upper side of the seat cushion body 10 is fixed on the seat cushion body 10, and its structural arrangement is specifically as Figure 3As shown. It is worth mentioning that the resistance of the pressure-sensitive fabric changes with the pressure it bears. By applying a fixed voltage on both sides of the fabric, the pressure at both ends can be determined from the current in the circuit. Among them, the top conductive fabric is grounded, and the bottom conductive fabric is respectively connected to the external processing unit 30 through conductive yarns for pressure signal analysis. Specifically, as Figure 2 shown, the conductive fabric on the lower side, that is, the conductive fabric close to the seat cushion body 10, is set to be connected to one end of a signal line, and the other end of the signal line is connected to the processing unit 30. That is, if there are 8 pressure fabric sensors 20, one ends of their 8 signal lines are respectively connected to the 8 conductive fabrics on the lower side, and the other ends are all connected to the processing unit 30. And it should be noted that the arrangement of the above 8 conductive fabrics and 8 signal lines is as Figure 2 shown. In addition, it should be noted that the processing unit 30 is arranged on the front side of the seat cushion body 10, that is, as Figure 3 shown in the structure of the seat cushion body 10, an arc-shaped embedding groove is provided on its front side, and the processing unit 30 is arranged in the arc-shaped embedding groove. And it is worth mentioning that the processing unit 30 can be implemented as a PCB circuit board, and it has at least 8 antennae that cooperate with the above signal lines. In addition, the PCB circuit board is also fixed in the arc-shaped embedding groove, and the PCB circuit board is installed in a shell, and the shell is in the shape of Figure 3 a crescent as shown. Its arc-shaped surface can fit the wall surface of the formed embedding groove. At the same time, the signal line can pass through the above shell and be connected to the PCB circuit board placed in the shell to perform pressure signal analysis.

[0033] Specifically, the pressure-sensitive fabric is nylon fiber infiltrated with polypyrrole, and the conductive fabric is carbon cloth woven from carbon fiber.

[0034] In addition, it should be noted that the conductive fabric far from the seat cushion body 10 is set to be connected to one end of a ground wire, and the other end of the ground wire is connected to the processing unit 30 to achieve grounding. Specifically, as Figure 2 shown in the wiring method. Among them, it should be noted that the above PCB circuit board is equipped with an embedded single-chip microcomputer to analyze the pressure signal to determine several postures. For example, if the human sitting posture is incorrect, such as leaning forward, backward or excessive pressure on one side, a single pressure fabric sensor 20 will transmit a pressure signal in a specific area to the circuit, and through analysis, a reminder will be given at the driver software end. In addition, the pressure fabric sensor 20 will also record the time when the electrode is under pressure to analyze the driver's continuous driving time and give a reminder. Specifically, as Figure 4As shown, eight pressure fabric sensors 20 are divided into four regions, which are hereinafter divided into A, B, C, and D. That is, the pressure signals in the four regions A, B, C, and D are analyzed to determine several postures, such as leaning left or right, forward or backward. It is worth mentioning that the above-mentioned pressure fabric sensor 20 has the advantage that it can be seamlessly integrated with the upper layer fabric of the seat cushion. The driver does not need to wear additional equipment, which greatly improves the comfort and convenience of wearing. The sensing seat cushion is light, replaceable, and machine washable, which improves the user's acceptance of the monitoring product. When the driver needs to change the monitoring environment, only the seat cushion needs to be moved, rather than the seat, which is applicable to fatigue driving monitoring in multiple scenarios. In addition, through the sensor array distributed in the fabric, the intelligent seat cushion cover can real-time monitor the pressure distribution between the human body and the seat. The pressure data is usually transmitted to the embedded single-chip microcomputer for real-time analysis. By analyzing the pressure data in different regions, it can be identified whether the driver is fatigued and whether there is a long-time driving behavior. This information will be timely feedback to the driver to help the driver make adjustments.

[0035] It should be noted that the size of the above-mentioned pressure-sensitive fabric can be implemented as 6×4 cm, and the size of the conductive fabric can be implemented as 5×3 cm, and they are sewn with non-conductive cotton thread to form a single pressure sensing electrode.

[0036] Hereinafter, a detection method for a pressure sensing seat cushion is provided, specifically:

[0037] S1: The seat cushion body 10 is set on the driver's seat. At the same time, the PCB circuit board integrates a wireless module, and a person sits on the seat cushion body 10 to collect the pressure data distribution of the sitting posture in advance. By collecting different driving postures of an individual during driving, the standard deviation function of the individual is recorded and calculated, and the data is transmitted to an external terminal. For example, someone often likes to drive with their legs crossed, and the discrete value of the electrode pair on the front right is relatively large, but someone is not distracted or fatigued while driving. In such a case, as long as the discrete value is not greater than the individual threshold of someone, it will not be judged as fatigued or distracted.

[0038] S2: The eight pressure fabric sensors 20 are classified in pairs of two to form four detection regions A, B, C, and D. At the same time, the PCB circuit board calculates the average pressure value of the four pairs of electrodes, and calculates the discrete value of each pair of electrodes through the standard deviation function, so as to judge whether there is an incorrect posture. Then, by calculating the average value of each pair of pressures, it is judged which sitting posture is incorrect. For example: if the discrete values of the two pairs of electrodes in the front are high and the average value is greater than that of the electrode pairs in the back, then there is a forward leaning posture.

[0039] S21: If the discrete values of the electrodes in regions A and B are high and at the same time satisfy that the average value is greater than that in regions C and D, it is judged as a backward leaning posture;

[0040] S22: If the electrode discrete values in regions C and D are high and, at the same time, the average value is greater than that in regions A and B, it is determined as a forward tilt posture.

[0041] S23: If the electrode discrete values in regions A and C are high and, at the same time, the average value is greater than that in regions B and D, it is determined as a right tilt posture.

[0042] S24: If the electrode discrete values in regions B and D are high and, at the same time, the average value is greater than that in regions A and C, it is determined as a left tilt posture.

[0043] S3: If the duration of the states of S21, S22, S23, and S24 is greater than 3 - 5 seconds, it is determined that the forward tilt posture, backward tilt posture, left tilt posture, or right tilt posture is valid. At the same time, the data is transmitted to an external terminal to feedback to the driver to help the driver adjust the posture.

[0044] S4: After the external transmission terminal feeds back the data to the driver, if the duration of the states of S21, S22, S23, and S24 still remains greater than 3 - 5 seconds, it is determined as fatigue driving. At the same time, the data is transmitted to an external terminal, and the external terminal emits an alarm sound through an alarm unit to remind the driver to adjust the posture.

[0045] It should be noted that the interval between the above - mentioned A detection region and B detection region is implemented as 26 mm, and the A detection region includes two pressure fabric sensors 20, hereinafter referred to as A1 sensor and A2 sensor, and the distance between the A1 sensor and the A2 sensor is implemented as 15 mm. At the same time, the B detection region includes B1 sensor and B2 sensor, and the distance between the B1 sensor and the B2 sensor is implemented as 15 mm. In addition, the C detection region includes C1 sensor and C2 sensor, and the D detection region includes D1 sensor and D2 sensor. The C1 sensor is located directly below the A1 sensor, and the distance is 41 mm. The C2 sensor is located directly below the A2 sensor, and the distance between the C2 sensor and the C1 sensor is 37 mm. Similarly, the D1 sensor is located directly below the B1 sensor, and the distance is 41 mm. The D2 sensor is located directly below the C2 sensor, and the distance between the D2 sensor and the D1 sensor is 37 mm.

[0046] In summary, the pressure - sensing seat cushion for driver fatigue detection according to the embodiments of the present application is clarified, which provides advantages such as convenient detection and convenient carrying for the pressure - sensing seat cushion for driver fatigue detection.

[0047] It is worth mentioning that, in the embodiments of the present application, the pressure sensing seat cushion for driver fatigue detection has a simple structure, does not involve complex manufacturing processes and expensive materials, and has high economy. At the same time, for manufacturers, the pressure sensing seat cushion for driver fatigue detection provided by the present application is easy to produce and has low costs, which is more conducive to controlling production costs and further conducive to the promotion and use of products.

[0048] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The object of the present invention has been fully and effectively achieved. The function and structural principle of the present invention have been shown and described in the embodiments, and without departing from this principle, the embodiments of the present invention can have any deformation or modification.

Claims

1. A pressure sensing seat cushion for driver fatigue detection, characterized in that: The pressure sensing seat cushion for driver fatigue detection comprises: A seat cushion body; Eight pressure fabric sensors are arranged on the cushion body, each of which includes a pressure-sensitive fabric and two conductive fabrics, the pressure-sensitive fabric is located between the two conductive fabrics, and the two conductive fabrics are fixed on the conductive fabrics, and the conductive fabric close to the upper side of the cushion body is fixed on the cushion body; The processing unit, the conductive fabric close to the cushion body is connected to one end of a signal line, and the other end of the signal line is connected to the processing unit, wherein the front side of the cushion body has an arc-shaped embedding groove, and the processing unit is arranged in the arc-shaped embedding groove, and the conductive fabric far from the cushion body is connected to one end of a ground line, and the other end of the ground line is connected to the processing unit; and The external terminal is connected to the processing unit, wherein the processing unit includes a PCB circuit board, and the PCB circuit board is provided with an embedded single-chip microcomputer for analyzing the pressure signal and transmitting the data to the external terminal.

2. The pressure sensing seat cushion for driver fatigue detection according to claim 1, wherein the pressure sensitive fabric is nylon fiber impregnated with polypyrrole, and the conductive fabric is carbon cloth woven from carbon fibers.

3. A pressure sensing seat cushion for driver fatigue detection according to claim 2, wherein the size of the pressure sensitive fabric can be implemented as 6×4 cm, and the size of the conductive fabric can be implemented as 5×3 cm, and the conductive fabric and the pressure sensitive fabric are sewn with non-conductive cotton thread to form a single pressure sensing electrode.

4. A method for detecting a pressure sensing cushion according to claim 3, characterized in that: The detection methods include: S1: The seat cushion body is set on the main driving seat, and the PCB circuit board is integrated with a wireless module, and a person sits on the seat cushion body to collect the sitting posture pressure data distribution in advance, and by collecting different driving sitting postures of the individual during driving, the individual's standard deviation function is recorded and calculated, and the data is transmitted to an external terminal; S2: The eight pressure fabric sensors are classified into pairs of two to form four detection areas A, B, C and D. At the same time, the PCB circuit board calculates the average pressure value of the four pairs of electrodes and calculates the discrete value of each pair of electrodes through the standard deviation function to determine whether an incorrect posture occurs.

5. The detection method according to claim 4, wherein the detection method further comprises: S21: If the discrete values ​​of the electrodes in the A and B regions are high and the average values ​​are greater than those in the C and D regions, it is determined to be a backward tilt posture; S22: If the discrete values ​​of the electrodes in the C and D regions are high and the average values ​​are greater than those in the A and B regions, it is determined to be a forward leaning posture; S23: If the electrode discrete values ​​in areas A and C are high and the average value is greater than that in areas B and D, it is determined to be a right-leaning posture; S24: If the discrete values ​​of the electrodes in the B and D regions are high and the average values ​​are greater than those in the A and C regions, it is determined to be a left-leaning posture.

6. The detection method according to claim 5, wherein the detection method further comprises, S3: if the state duration of S21, S22, S23 and S24 is greater than 3-5 seconds, it is judged that the forward leaning posture, the backward leaning posture, the left leaning posture or the right leaning posture is valid, and the data is transmitted to an external terminal at the same time to be fed back to the driver to help the driver adjust the posture.

7. The detection method according to claim 6, wherein the detection method further includes, S4: after the external terminal feeds back the data to the driver, if the states of S21, S22, S23 and S24 continue for more than 3-5 seconds, it is judged as fatigue driving, and the data is transmitted to the external terminal at the same time, and the external terminal sends an alarm through the alarm unit to remind the driver to adjust his posture.

8. The detection method according to claim 4, wherein the interval between detection area A and detection area B is 26 mm.

9. The detection method according to claim 8, wherein the A detection area includes an A1 sensor and an A2 sensor, the distance between the A1 sensor and the A2 sensor is implemented as 15 mm, and the B detection area includes a B1 sensor and a B2 sensor, and the distance between the B1 sensor and the B2 sensor is implemented as 15 mm.

10. The detection method according to claim 9, wherein the C detection area includes a C1 sensor and a C2 sensor, and the D detection area includes a D1 sensor and a D2 sensor, the C1 sensor is located directly below the A1 sensor, and the spacing is 41 mm, the C2 sensor is located directly below the A2 sensor, and the spacing between the C2 sensor and the C1 sensor is 37 mm, similarly, the D1 sensor is located directly below the B1 sensor, and the spacing is 41 mm, the D2 sensor is located directly below the C2 sensor, and the spacing between the D2 sensor and the D1 sensor is 37 mm.

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