A cargo displacement detection method based on capacitive change

Abstract

The present invention discloses a cargo displacement detection method based on capacitance change. In order to overcome the problem that high-precision capacitance displacement detection is not suitable for cargo transportation processes with bumps and jitters; the present invention includes: S1: arranging and setting a number of detection capacitors in the corresponding areas of the carriage wall and the cargo, and for the same detection capacitor, setting a number of capacitor plates at intervals along the horizontal direction on the carriage wall to form a first capacitor plate group; S2: respectively monitoring and recording the capacitance changes between each capacitor plate in the first capacitor plate group and the capacitor plate on the cargo during transportation; S3: judging whether the cargo has been displaced and the direction of the cargo displacement based on the capacitance change, and issuing an alarm. For the same group of detection capacitors, capacitor plate groups are set at intervals on the carriage wall, and the displacement detection along the carriage direction is converted from capacitance value detection calculation to judgment of whether there is capacitance between the capacitor plates. The judgment is more macroscopic, and avoids the influence of capacitance value changes caused by bumps and jitters during transportation.

Description

Technical Field

[0001] The present invention relates to the field of cargo displacement detection, and in particular to a cargo displacement detection method based on capacitive change. Background Art

[0002] At present, the demand for road freight has increased significantly, and therefore the freight volume has also increased significantly. However, during the transportation process, the goods may slide, roll or fall, which has a certain impact on the safety of the goods, personal safety and road safety, and is likely to cause huge economic losses. Therefore, it is necessary to detect the displacement of the goods during transportation.

[0003] Capacitive sensors, as a displacement measurement method, can also be used to detect the displacement of transported goods. It's known that two parallel conductive electrodes form a capacitor. The capacitance of a capacitor is approximately proportional to the dielectric constant of the medium between the parallel electrodes, proportional to the relative (overlapping) area of ​​the two electrodes, and inversely proportional to the gap between them. Therefore, the capacitance varies with the relative area and gap between the two electrodes.

[0004] Based on the above principle, the displacement of the object under test can be determined by detecting changes in capacitance. However, the capacitance of a capacitor is very sensitive to changes in the gap, especially when the gap is very small. In the bumpy and jittery transportation process of goods, such subtle changes can actually cause interference.

[0005] For example, a "detection device for variable-area displacement capacitor" disclosed in Chinese patent literature, with publication number CN109341744A, includes: a variable-area displacement capacitor detection structure, a driving voltage module, and a charge amplifier; the variable-area displacement capacitor detection structure includes: a detection capacitor and a moving block; the driving voltage module generates positive and negative driving carriers for displacement capacitor detection and loads them on the detection capacitor respectively; the charge amplifier includes: a feedback capacitor, a feedback resistor, and an operational amplifier, and the charge amplifier is used to compare the differential capacitance change caused by a small displacement with the feedback capacitance and convert it into a voltage signal; when detecting external displacement, the displacement in the detection direction causes the area facing the detection capacitor to change, thereby changing the size of the detection capacitor, and the purpose of displacement detection is achieved by detecting the capacitance change caused by the area change; the influence of the change in the distance between the moving and fixed plates on the differential capacitance is eliminated, thereby improving the detection accuracy of the displacement capacitor. However, this solution is not suitable for cargo transportation processes with bumps and shakes. Summary of the Invention

[0006] The present invention mainly solves the problem that the high-precision capacitive displacement detection in the existing technology is not suitable for cargo transportation processes with bumps and jitters; it provides a cargo displacement detection method based on capacitive changes, which eliminates the impact of detection caused by bumps and jitters during transportation through the layout of capacitors.

[0007] The above technical problems of the present invention are mainly solved by the following technical solutions:

[0008] A cargo displacement detection method based on capacitive change, comprising:

[0009] S1: Arrange a number of detection capacitors in the corresponding areas of the carriage wall and the cargo. For the same detection capacitor, a number of capacitor plates are arranged horizontally on the carriage wall at intervals to form a first capacitor plate group;

[0010] S2: During transportation, the capacitance changes between each capacitor in the first capacitor group and the capacitor on the cargo are monitored and recorded respectively; S3: Based on the capacitance changes, whether the cargo has been displaced and the direction of the displacement are determined, and an alarm is issued.

[0011] For the same set of detection capacitors, capacitor plate groups are set at intervals on the carriage wall, and the displacement detection along the carriage direction is converted from the detection calculation of the capacitance value to the judgment of whether there is capacitance between the capacitor plates. The judgment is more macroscopic and avoids the influence of capacitance value changes caused by bumps and vibrations during transportation.

[0012] Preferably, a second capacitor plate is provided on the side of the cargo corresponding to the first capacitor plate group, and the first capacitor plate group includes a detection capacitor plate and at least a pair of offset capacitor plates provided on both sides of the detection capacitor plate.

[0013] The change in capacitance between the offset capacitor and the second capacitor can be used to determine whether the cargo has moved, as well as the direction and approximate distance of the displacement.

[0014] Preferably, the second capacitor sheet is directly opposite to the detection capacitor sheet, and margins exist in the facing area at least on both sides of the detection capacitor sheet.

[0015] When the cargo is stable, the second capacitor plate has a smaller area than the detection capacitor plate, so the capacitance between the detection and second capacitor plates is calculated using the area of ​​the second capacitor plate as the facing area. Because a blank margin is left on the detection capacitor plate in the facing area relative to the cargo's displacement, even if the cargo is jolted, the facing area remains within the detection capacitor plate's range, and thus, jolting and shaking will not affect the capacitance between the detection and second capacitor plates.

[0016] Preferably, a third capacitor plate is provided on the compartment wall in an area corresponding to the tray, and a fourth capacitor plate is provided on a side surface corresponding to the tray. The third capacitor plate and the fourth capacitor plate constitute a fixed capacitor.

[0017] The capacitance of the fixed capacitor is used as a reference value to determine whether the cargo is close to the carriage wall and to eliminate the shaking of the cargo toward the carriage wall.

[0018] Preferably, the capacitance obtained by subtracting the capacitance of the detection capacitor in the corresponding area from the capacitance of the fixed capacitor is used as the proximity judgment capacitance; when the change in the proximity judgment capacitance is greater than the proximity threshold, it is determined that the cargo is displaced toward the car wall; otherwise, the process ends.

[0019] During the cargo transportation process, the cargo will also be displaced toward the carriage wall. By subtracting the capacitance value of the fixed capacitor, the vibration in the direction close to the carriage wall is eliminated, making the displacement calculation in the approaching direction more accurate.

[0020] Preferably, the step S3 comprises the following steps:

[0021] S301: Determine whether the capacitance between the detection capacitor plate and the second capacitor plate has changed. If so, proceed to the next step of determination; otherwise, continue the determination of this step;

[0022] S302: Determine whether the capacitance between the offset capacitor plate and the second capacitor plate has changed. If so, proceed to the next step; otherwise, calculate the displacement of the cargo in the direction of approaching the carriage wall.

[0023] S303: Determine the displacement direction of the cargo based on the position of the offset capacitor sheet with changed capacitance relative to the detection capacitor sheet;

[0024] S304: Quantitatively calculating the cargo displacement distance based on the capacitance change between the offset capacitor plate and the second capacitor plate.

[0025] Preferably, the quantitative calculation process is specifically expressed as follows:

[0026]

[0027] Among them, D e is the cargo displacement;

[0028] α is the number of offset capacitors whose facing area covers all the offset capacitors;

[0029] d e is the width of the offset capacitor;

[0030] β is the coefficient of variation of the opposite area and displacement;

[0031] C all To detect the capacity value of the capacitor in real time;

[0032] ΔC is the difference between the real-time proximity judgment capacitance value and the initial proximity judgment capacitance value;

[0033] C s is the standard value of capacitance between the offset capacitor plate and the second capacitor plate at the initial distance and the maximum facing area;

[0034] γ is the coefficient of variation of the capacity value and the facing area at the initial distance.

[0035] Preferably, the expression for the difference ΔC between the real-time proximity judgment capacitance value and the initial proximity judgment capacitance value is:

[0036] ΔC=C t -C0

[0037] C t =C all -C pt

[0038] C0=C c0 -C p0

[0039] Among them, C t To approach the capacity value in real time;

[0040] C0 is the initial proximity judgment capacitance value;

[0041] C pt is the capacity value of the real-time fixed capacitor;

[0042] C c0 is the capacity value of the initial detection capacitor;

[0043] C p0 is the initial fixed capacitor capacity value.

[0044] The beneficial effects of the present invention are:

[0045] For the same set of detection capacitors, capacitor plate groups are set at intervals on the carriage wall, and the displacement detection along the carriage direction is converted from the detection calculation of the capacitance value to the judgment of whether there is capacitance between the capacitor plates. The judgment is more macroscopic and avoids the influence of capacitance value changes caused by bumps and vibrations during transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flow chart of the cargo displacement detection method of the present invention.

[0047] Figure 2 The present invention is a schematic diagram of the installation of a capacitor plate on a carriage wall.

[0048] In the figure, 1. detection capacitor plate, 2. offset capacitor plate, 3. third capacitor plate, 4. facing area. DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0050] Example:

[0051] A cargo displacement detection method based on capacitive change in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0052] S1: Arrange and set a number of detection capacitors in the corresponding areas of the carriage wall and the cargo. For the same detection capacitor, a number of capacitor plates are arranged at intervals along the horizontal direction on the carriage wall to form a first capacitor plate group.

[0053] A second capacitor plate is set on the side of the cargo corresponding to the first capacitor plate group, such as Figure 2 As shown, the first capacitor plate group includes a detection capacitor plate 1 and at least one pair of offset capacitor plates 2 disposed on both sides of the detection capacitor plate 1. In this embodiment, three offset capacitor plates 2 are disposed on the left and right sides of the detection capacitor plate 1, respectively. That is, three pairs of offset capacitor plates 2 are disposed on both sides of the detection capacitor plate 1.

[0054] The change in capacitance between the offset capacitor plate 2 and the second capacitor plate can be used to determine whether the cargo has been displaced, as well as the direction and approximate distance of the displacement.

[0055] The second capacitor piece is directly opposite to the detection capacitor piece 1, such as Figure 2 The shaded portion shown is the facing area 4 ; the facing area has margins at least on two sides within the detection capacitor plate 1 .

[0056] In this embodiment, a certain margin exists in the facing area around the detection capacitor plate 1 .

[0057] When the cargo is stable, the second capacitor plate is smaller than the detection capacitor plate in area, so the capacitance between the detection and second capacitor plates is calculated using the second capacitor plate as the facing area. Because a margin is left on the detection capacitor plate in the facing area relative to the cargo's movement, even if the cargo is jolted, the facing area remains within the detection capacitor plate's range, and thus, the jolting will not affect the capacitance between the detection and second capacitor plates.

[0058] S2: During transportation, the capacitance change between each capacitor in the first capacitor group and the capacitor on the cargo is monitored and recorded.

[0059] The capacitance value between the detection capacitor plate 1 and the second capacitor plate, as well as the capacitance value between each offset capacitor plate 2 and the second capacitor plate, are recorded separately. The change in capacitance between the offset capacitor plate 2 and the second capacitor plate can be used to determine whether the cargo has moved, as well as the direction and approximate distance of the movement.

[0060] For the same set of detection capacitors, capacitor plate groups are set at intervals on the carriage wall, and the displacement detection along the carriage direction is converted from the detection calculation of the capacitance value to the judgment of whether there is capacitance between the capacitor plates. The judgment is more macroscopic and avoids the influence of capacitance value changes caused by bumps and vibrations during transportation.

[0061] S3: Determine whether the cargo has been displaced and the direction of displacement based on the change in capacitance, and issue an alarm.

[0062] S301: Determine whether the capacitance between the detection capacitor plate and the second capacitor plate has changed. If so, proceed to the next step of determination; otherwise, continue the determination of this step.

[0063] If the capacitance between the detection capacitor plate 1 and the second capacitor plate changes, it may be that the cargo has moved toward the car wall or along the length of the car, and further judgment is required. Otherwise, it is judged that there is no cargo displacement.

[0064] S302: Determine whether the capacitance between the offset capacitor plate and the second capacitor plate has changed. If so, proceed to the next step; otherwise, calculate the displacement of the cargo in the direction of approaching the carriage wall.

[0065] like Figure 2 As shown, a third capacitor plate 3 is provided on the compartment wall corresponding to the tray area, and a fourth capacitor plate is provided on the side surface corresponding to the tray. The third capacitor plate 3 and the fourth capacitor plate constitute a fixed capacitor.

[0066] The capacitance of the fixed capacitor is used as a reference value to determine whether the cargo is close to the carriage wall and to eliminate the shaking of the cargo toward the carriage wall.

[0067] The capacitance value obtained by subtracting the capacitance value of the detection capacitor in the corresponding area from the capacitance value of the fixed capacitor is used as the proximity judgment capacitance value; when the change in the proximity judgment capacitance value is greater than the proximity threshold value, it is determined that the cargo is displaced toward the carriage wall; otherwise, the process ends.

[0068] During the cargo transportation process, the cargo will also be displaced toward the carriage wall. By subtracting the capacitance value of the fixed capacitor, the vibration in the direction close to the carriage wall is eliminated, making the displacement calculation in the approaching direction more accurate.

[0069] The distance between the cargo and the carriage wall is calculated by detecting the capacitance value between the first capacitor and the second capacitor.

[0070] S303: Determine the displacement direction of the cargo according to the position of the offset capacitor sheet with changed capacitance relative to the detection capacitor sheet.

[0071] The change in capacitance between the offset capacitor plate 2 and the second capacitor plate can be used to determine whether the cargo has been displaced, as well as the direction and approximate distance of the displacement.

[0072] S304: Quantitatively calculating the cargo displacement distance based on the capacitance change between the offset capacitor plate and the second capacitor plate.

[0073] The quantitative calculation process is specifically expressed as:

[0074]

[0075] Among them, D e is the cargo displacement.

[0076] α is the number of offset capacitors whose facing area covers all the offset capacitors.

[0077] d e is the width of the offset capacitor.

[0078] β is the coefficient of variation of the opposite area and displacement.

[0079] C all To detect the capacitance value of the capacitor in real time.

[0080] ΔC is the difference between the real-time proximity judgment capacitance value and the initial proximity judgment capacitance value.

[0081] C s is the standard value of capacitance between the offset capacitor plate and the second capacitor plate at the initial distance and the maximum facing area;

[0082] γ is the coefficient of variation of the capacity value and the facing area at the initial distance.

[0083] The expression of the difference ΔC between the real-time proximity judgment capacitance value and the initial proximity judgment capacitance value is:

[0084] ΔC=C t -C0

[0085] C t =C all -C pt

[0086] C0=C c0 -C p0

[0087] Among them, C t To judge the capacitance value in real time.

[0088] C0 is the initial proximity judgment capacitance value.

[0089] C pt It is the capacity value of the real-time fixed capacitor.

[0090] C c0 is the capacitance value of the initial detection capacitor.

[0091] C p0is the initial fixed capacitor capacity value.

[0092] When displacement occurs in two directions simultaneously, the displacement along the carriage direction is calculated first, and then the displacement distance of the cargo toward the carriage wall is calculated based on the difference between the actual detected capacitance and the capacitance change caused by the displacement along the carriage direction.

[0093] The solution of this embodiment is to set capacitor plate groups at intervals on the carriage wall for the same group of detection capacitors, and convert the displacement detection along the carriage direction from the detection calculation of the capacitance value to the judgment of whether there is capacitance between the capacitor plates. The judgment is more macroscopic and avoids the influence of capacitance value changes caused by bumps and vibrations during transportation.

[0094] It should be understood that the embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the appended claims of the application.

Claims

1. A cargo displacement detection method based on capacitive change, characterized in that: include: S1: Arrange a number of detection capacitors in the corresponding areas of the carriage wall and the cargo. For the same detection capacitor, a number of capacitor plates are arranged horizontally on the carriage wall at intervals to form a first capacitor plate group; S2: During transportation, the capacitance change between each capacitor in the first capacitor group and the capacitor on the cargo is monitored and recorded; S3: Determine whether the cargo has moved and the direction of the displacement based on the change in capacitance, and issue an alarm; Among them, a second capacitor plate is set on the side of the goods corresponding to the first capacitor plate group. The first capacitor plate group includes a detection capacitor plate and at least a pair of offset capacitor plates arranged on both sides of the detection capacitor plate. The second capacitor plate is directly opposite to the detection capacitor plate, and there is a margin in the facing area on at least both sides of the detection capacitor plate.

2. The cargo displacement detection method based on capacitive change according to claim 1, characterized in that: A third capacitor sheet is provided on the carriage wall in the area corresponding to the tray, and a fourth capacitor sheet is provided on the side surface corresponding to the tray. The third capacitor sheet and the fourth capacitor sheet form a fixed capacitor.

3. The cargo displacement detection method based on capacitive change according to claim 2, characterized in that: The capacitance value obtained by subtracting the capacitance value of the detection capacitor in the corresponding area from the capacitance value of the fixed capacitor is used as the proximity judgment capacitance value; When the change in the proximity judgment capacitance value is greater than the proximity threshold, it is determined that the cargo is displaced toward the carriage wall; otherwise, the process ends.

4. A cargo displacement detection method based on capacitive change according to claim 2 or 3, characterized in that: The step S3 comprises the following steps: S301: Determine whether the capacitance between the detection capacitor plate and the second capacitor plate has changed. If so, proceed to the next step of determination; otherwise, continue the determination of this step; S302: Determine whether the capacitance between the offset capacitor plate and the second capacitor plate has changed. If so, proceed to the next step; otherwise, calculate the displacement of the cargo in the direction of approaching the carriage wall. S303: Determine the displacement direction of the cargo based on the position of the offset capacitor sheet with changed capacitance relative to the detection capacitor sheet; S304: Quantitatively calculating the cargo displacement distance based on the capacitance change between the offset capacitor plate and the second capacitor plate.

5. The cargo displacement detection method based on capacitive change according to claim 4, characterized in that: The quantitative calculation process is specifically expressed as follows: Among them, D e is the cargo displacement; α is the number of offset capacitors whose facing area covers all the offset capacitors; d e is the width of the offset capacitor; β is the coefficient of variation of the opposite area and displacement; C all To detect the capacity value of the capacitor in real time; ΔC is the difference between the real-time proximity judgment capacitance value and the initial proximity judgment capacitance value; C s is the standard value of capacitance between the offset capacitor plate and the second capacitor plate at the initial distance and the maximum facing area; γ is the coefficient of variation of the capacity value and the facing area at the initial distance.

6. The cargo displacement detection method based on capacitive change according to claim 5, characterized in that: The expression for the difference ΔC between the real-time proximity judgment capacitance value and the initial proximity judgment capacitance value is: ΔC=C t -C0 C t =C all =C pt C0=C c0 -c p0 Among them, C t To approach the capacity value in real time; C0 is the initial proximity judgment capacitance value; C pt is the capacity value of the real-time fixed capacitor; C c0 is the capacity value of the initial detection capacitor; C p0 is the initial fixed capacitor capacity value.

7. According to the cargo displacement detection method based on capacitive change in claim 4, when displacement occurs in two directions simultaneously, the displacement along the car body direction is first calculated, and then the displacement distance of the cargo toward the car body wall is calculated based on the difference between the actual detected capacitance and the capacitance change caused by the displacement along the car body direction.

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