A method for judging plume type and delimiting search range of pollution source tracking

Abstract

The present application proposes a method for judging the plume type in advance and defining the tracking range of the pollution source of the unmanned aerial vehicle, which is used for gas leakage source positioning. The accuracy of the judgment is improved by calculating atmospheric stability, calculating plume expansion rate and calculating plume boundary slope. By determining the plume type, the boundary position of the plume is inferred, and the search range of the pollution source tracking is defined based on this, so that the unmanned aerial vehicle can reduce unnecessary space search when tracking, and improve the efficiency of pollution source tracking and positioning. Computer simulation verifies that the method can effectively improve the efficiency of pollution source tracking and positioning.

Description

Technical Field

[0001] This invention relates to the fields of environment and computer science, and in particular to a method for determining plume type and defining the search range for pollution sources. Background Technology

[0002] With my country's rapid economic development, serious air pollution has resulted from illegal industrial emissions, vehicle exhaust, and uncivilized behaviors in agricultural production. Due to their high flexibility and ease of deployment, drones are increasingly used in environmental monitoring, facilitating the proactive tracking and location of gas leaks. Currently, different researchers have proposed various algorithms to quickly and accurately locate pollution sources, but these search methods lack specificity for different plume types.

[0003] Meteorological parameters such as wind, temperature, humidity, and pressure exhibit vertical shear at different altitudes, and the vertical distribution of these parameters determines the shape and profile of the plume emitted by the pollution source. Based on their shape characteristics, plumes are generally classified into five types: flat, ridge-shaped, wavy, smoke-like, and conical.

[0004] Uncertain plume type leads to an unclear search range, causing the drone to perform unnecessary spatial searches during tracking, increasing the drone's power consumption and reducing tracking efficiency. Summary of the Invention

[0005] To address the aforementioned problems, this invention determines the type of smoke plume being tracked by a drone by calculating atmospheric stability and acquiring plume characteristics, and infers the boundary position of the plume, reducing unnecessary spatial searches by the drone during plume tracking and improving the efficiency of pollution source tracking and location. The invention provides the following technical solution: a method for determining plume type and defining the search range for tracking pollution sources, comprising the following steps:

[0006] Step 1: At coordinates (x0, y0), the drone carrying both a temperature sensor and a gas concentration sensor is vertically ascended, and the temperature T is measured every h meters. ih , where i is the temperature obtained at the i-th time. Stop at a height of H meters and record the coordinates (x1, y1).

[0007] Step 2: Calculate the vertical temperature lapse rate γ based on the temperature variation with altitude. Where T is the temperature and Z is the flight altitude of the drone.

[0008] Step 3: Compare γ with the dry adiabatic vertical lapse rate γ d By comparison, plume type I was determined.

[0009] Step 3.1: In step 3, if γ is first greater than 0 and then greater than γ dIf the value is less than 0, then the plume type is smoke type.

[0010] Step 3.2: In step 3, if γ is always greater than 0 and greater than γ d If so, the plume type is wavy.

[0011] Step 3.3: In step 3, if γ is always greater than 0 and less than γ d If so, the plume type is conical.

[0012] Step 3.4: In step 3, if γ is always less than 0, then the plume type is flat.

[0013] Step 3.5: In step 3, if γ is first less than 0 and then greater than 0, then the plume type is ascending.

[0014] Step 4: The UAV performs a planar reciprocating profile measurement, with a horizontal distance of M meters between the reciprocating trips and a gas concentration Q acquired every N meters longitudinally. ij , where i is the i-th column that the drone flies to during the traversal, j is the j-th point sampled by the drone in that column, and a total of n columns are flown.

[0015] Step 5: When the concentration difference between adjacent gases is greater than δ, but one of the concentrations is 0, i.e., |Q ij -Q i(j-1) |≥δ and Q ij ×Q i(j-1) When = 0, let Q be denoted as . ij With Q i(j-1) The point with the larger coordinate value is the boundary point P. i1 (x i1 y i1 ), P i2 (x i2 y i2 ), where the point with the larger y-value is P. i1 (x i1 y i1 Where δ is the preset concentration difference threshold, mass fraction / m 3 .

[0016] Step 6: According to formula D i =|y i1 -y i2 Calculate the vertical width D of the i-th column of the smoke plume. i The plume spread is determined based on the longitudinal width, and the plume type is identified as II.

[0017] Step 6.1: In step 6, if the overall trend of plume width is from small to large but there are occasional alternations in size, then the plume type is wavy.

[0018] Step 6.2: In step 6, if the plume width increases from small to large, the plume type is conical, ascending, or smoke-filled. Calculate P. i1 (x i1 y i1 ), P i2 (x i2 y i2 midpoint Connect the lines and fit a straight line with a slope of k1. Compare k1 with tanθ, where θ is the set angle.

[0019] Step 6.2.1: In step 6.2, if k1 is greater than tanθ, then the plume type is ascending.

[0020] Step 6.2.2: In step 6.2, if k1 is less than -tanθ, then the plume type is smoke type.

[0021] Step 6.2.3: In step 6.2, if k1 is less than tanθ and greater than -tanθ, then the plume type is conical.

[0022] Step 6.3: In step 6, if the plume width does not change significantly, the plume type is flat.

[0023] Step 7: Compare the results of plume I and plume II obtained in the above steps.

[0024] Step 7.1: In step 7, if the two plume types are the same, the shape of the measured plume is obtained, and the measured upper boundary point and lower boundary point are fitted into straight lines respectively. The area between the two straight lines is the pollution source search range of the planar UAV.

[0025] Step 7.2: In step 7, if the two plume types are not consistent, the plume type III is determined by the third plume type evaluation method.

[0026] Step 8: P from step 5 i1 With P i2 The two lines are fitted separately, and their slopes are compared with tanα to determine the shape of the plume. The slope of the upper boundary is k2, the slope of the lower boundary is k3, and α is the set angle.

[0027] Step 8.1: In step 8, if both k2 and k3 are greater than tanα, then the plume type is wavy.

[0028] Step 8.2: In step 8, if k2 is greater than tanα and k3 is greater than 0 and less than tanα, then the plume type is ascending.

[0029] Step 8.3: In step 8, if k2 is greater than 0 and less than tanα, and k3 is less than -tanα, then the plume type is smoke plume.

[0030] Step 8.4: In step 8, if k2 is greater than tanα and k3 is less than -tanα, then the plume type is conical.

[0031] Step 8.5: In step 8, if the absolute values ​​of k2 and k3 are both less than tanα, then the plume type is flat.

[0032] Step 9: Statistically analyze the three types of plume: I, II, and III. The repeated plume types represent the shape of the current plume.

[0033] Step 10: The area between the two straight lines generated in Step 8 is the search range for pollution sources by the planar UAV.

[0034] The beneficial effects of this invention are as follows:

[0035] This invention determines the type of smoke plume being tracked by a drone by calculating atmospheric stability and acquiring smoke plume characteristics, and infers the boundary position of the smoke plume to determine the range for the drone to search for pollution sources. This reduces unnecessary spatial searches by the drone during smoke plume tracking and improves the efficiency of pollution source tracking and location. Figure 4 For a comparison chart showing whether or not this method was used, from... Figure 4 It is evident that using this method significantly improves the speed at which drones reach the vicinity of pollution sources, without affecting the accuracy of locating pollution sources.

[0036] This invention integrates three methods for determining plume type, thereby improving its reliability. By using multiple methods to determine plume type from multiple perspectives, the possibility of misjudgment is reduced. Attached Figure Description

[0037] Figure 1 This is a flowchart of the algorithm of the present invention.

[0038] Figure 2 A schematic diagram of the sampling location of the UAV for determining plume type I.

[0039] Figure 3 A schematic diagram of the UAV sampling locations for determining plume types II and III.

[0040] Figure 4 This is a comparison chart showing whether or not this method was used. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0042] A method for determining plume type and defining the search area for pollution sources, the flowchart of which is as follows: Figure 1 As shown, the specific steps are as follows:

[0043] Step 1: At coordinates (x0, y0), the drone carrying both a temperature sensor and a gas concentration sensor is vertically ascended, and the temperature T is measured every h meters. i·h , where i is the temperature obtained at the i-th time. Stop at a height of H meters and record the coordinates (x1, y1).

[0044] In this embodiment, at the initial coordinates (25, 0), the drone carrying both a temperature sensor and a gas concentration sensor is vertically ascended, and the temperature T is measured every 1m. h T1 = 25.04℃. Stop at 20m and record the coordinates (25, 20).

[0045] Step 2: Calculate the vertical temperature lapse rate γ based on the temperature variation with altitude. Where T is the temperature and Z is the flight altitude of the drone.

[0046] In this embodiment, the vertical temperature lapse rate γ is calculated based on the change in temperature with altitude.

[0047] Step 3: Compare γ with the dry adiabatic vertical lapse rate γ d By comparison, plume type I was determined.

[0048] Step 3.1: In step 3, if γ is first greater than 0 and then greater than γ d If the value is less than 0, then the plume type is smoke type.

[0049] Step 3.2: In step 3, if γ is always greater than 0 and greater than γ d If so, the plume type is wavy.

[0050] Step 3.3: In step 3, if γ is always greater than 0 and less than γ d If so, the plume type is conical.

[0051] Step 3.4: In step 3, if γ is always less than 0, then the plume type is flat.

[0052] Step 3.5: In step 3, if γ is first less than 0 and then greater than 0, then the plume type is ascending.

[0053] In this implementation case, γ = 0.7475℃ / 100m, γ d =0.98℃ / 100m. After comparison, it was found that the plume type I is conical.

[0054] Step 4: The UAV performs a planar reciprocating profile measurement, with a horizontal distance of M meters between the reciprocating trips and a gas concentration Q acquired every N meters longitudinally. ij , where i is the i-th column that the drone flies to during the traversal, j is the j-th point sampled by the drone in that column, and a total of n columns are flown.

[0055] In this implementation case, the UAV performs planar reciprocating profile measurements, with a horizontal reciprocating interval of 0.5m, and acquires the gas concentration Q every 1m longitudinally. ij Q 23 =0.0006 mass fraction / m 3 That is, the gas concentration value in the second column and third row is 0.0006 mass fraction / m³. 3 A total of 10 round trips were made.

[0056] Step 5: When the concentration difference between adjacent gases is greater than δ, but one of the concentrations is 0, i.e., |Q ij -Q i(j-1) |≥δ and Q ij ×Q i(j-1) When = 0, let Q be denoted as . ij With Q i(j-1) The point with the larger coordinate value is the boundary point P. i1 (x i1 y i1 ), P i2 (x i2 y i2 ), where the point with the larger y-value is P. i1 (x i1 y i1 Where δ is the preset concentration difference threshold, mass fraction / m 3 .

[0057] In this implementation example, the concentrations of adjacent gases are Q. 319 =0.0005 mass fraction / m 3 Q 320 =0 mass fraction / m 3 The difference is equal to δ = 0.0005 mass fraction / m 3 The two boundary points in the third column are (24, 4) and (24, 19). Since y = 19 is greater than 3, we denote (24, 19) as P. 31 (24, 4) is P 32 .

[0058] Step 6: According to formula D i =|y i1 -y i2 Calculate the vertical width D of the i-th column of the smoke plume. i The plume spread is determined based on the longitudinal width, and the plume type is identified as II.

[0059] Step 6.1: In step 6, if the overall trend of plume width is from small to large but there are occasional alternations in size, then the plume type is wavy.

[0060] Step 6.2: In step 6, if the plume width increases from small to large, the plume type is conical, ascending, or smoke-filled. Calculate P. i1 (x i1 y i1 ), P i2 (x i2 y i2 midpoint Connect the lines and fit a straight line with a slope of k1. Compare k1 with tanθ, where θ is the set angle.

[0061] Step 6.2.1: In step 6.2, if k1 is greater than tanθ, then the plume type is ascending.

[0062] Step 6.2.2: In step 6.2, if k1 is less than -tanθ, then the plume type is smoke type.

[0063] Step 6.2.3: In step 6.2, if k1 is less than tanθ and greater than -tanθ, then the plume type is conical.

[0064] In this implementation case, D3 = 15 is calculated according to the formula, and the plume width increases from smallest to largest. The midpoint P of column 3... 30 (24, 11.5). Taking θ = 15°, k1 = 0.2068, k1 < tan15°. Based on the results, the plume type is conical.

[0065] Step 7: Compare plume I and plume II obtained from the above steps.

[0066] Step 7.1: In step 7, if the two plume types are the same, the shape of the measured plume is obtained, and the measured upper boundary point and lower boundary point are fitted into straight lines respectively. The area between the two straight lines is the pollution source search range of the planar UAV.

[0067] Step 7.2: In step 7, if the two plume types are not consistent, the plume type III is determined by the third plume type evaluation method.

[0068] In this embodiment, the two plume types are the same, so the measured plume type is conical. According to the fitting, the upper boundary line is y = 7.478 + 0.4060·x, the lower boundary line is y = 3.902 - 0.00752·x, and the area between the two lines is the pollution source search range of the planar UAV.

[0069] Step 8: P from step 5 i1 With Pi2 The two lines are fitted separately, and their slopes are compared with tanα to determine the shape of the plume. The slope of the upper boundary is k2, the slope of the lower boundary is k3, and α is the set angle.

[0070] Step 8.1: In step 8, if both k2 and k3 are greater than tanα, then the plume type is wavy.

[0071] Step 8.2: In step 8, if k2 is greater than tanα and k3 is greater than 0 and less than tanα, then the plume type is ascending.

[0072] Step 8.3: In step 8, if k2 is greater than 0 and less than tanα, and k3 is less than -tanα, then the plume type is smoke plume.

[0073] Step 8.4: In step 8, if k2 is greater than tanα and k3 is less than -tanα, then the plume type is conical.

[0074] Step 8.5: In step 8, if the absolute values ​​of k2 and k3 are both less than tanα, then the plume type is flat.

[0075] Step 9: Statistically analyze the three types of plume: I, II, and III. The repeated plume types represent the shape of the current plume.

[0076] Step 10: The area between the two straight lines generated in Step 8 is the search range for pollution sources by the planar UAV.

Claims

1. A method for determining plume type and defining the search area for pollution sources, characterized in that, Includes the following steps: Step 1: At coordinates (x0, y0), the drone carrying both a temperature sensor and a gas concentration sensor is vertically ascended, and the temperature T is measured every h meters. ih , where i is the i-th temperature acquisition, stopping at a height of H meters, and recording the coordinates (x1, y1); Step 2: Calculate the vertical temperature lapse rate γ based on the temperature variation with altitude. Where T is the temperature and Z is the flight altitude of the drone; Step 3: Compare γ with the dry adiabatic vertical lapse rate γ d By comparison, plume type I was determined; Step 4: The UAV performs a planar reciprocating profile measurement, with a horizontal distance of M meters between the reciprocating trips and a gas concentration Q acquired every N meters longitudinally. ij , where i is the i-th column that the drone flies to during the traversal, j is the j-th point sampled by the drone in that column, and a total of n columns are flown; Step 5: When the concentration difference between adjacent gases is greater than δ, but one of the concentrations is 0, i.e., |Q ij -Q i(j-1) |≥δ and Q ij ×Q i(j-1) When = 0, denote Q as 0. ij With Q i(j-1) The point with the larger coordinate value is the boundary point P. i1 (x i1 y i1 ), P i2 (x i2 y i2 ), where the point with the larger y-value is P. i1 (x i1 y i1 ), where δ is a preset concentration difference threshold, mass fraction / m 3 ; Step 6: According to formula D i =|y i1 -y i2 Calculate the vertical width D of the i-th column of the smoke plume. i The plume spread is determined based on the longitudinal width, and the plume type is identified as II. Step 7: Compare plume I and plume II obtained from the above steps: Step 7.1: In step 7, if the two plume types are the same, the shape of the measured plume is obtained, and the measured upper boundary point and lower boundary point are fitted into straight lines respectively. The area between the two straight lines is the pollution source search range of the planar UAV. Step 7.2: In step 7, if the two plume types are not consistent, the plume type III shall be determined by the third plume type evaluation method; Step 8: P from step 5 i1 With P i2 The two lines are fitted separately and their slopes are compared with tanα to determine the shape of the plume. The slope of the upper boundary is k2, the slope of the lower boundary is k3, and α is the set angle. Step 9: Statistically analyze the three types of plume: I, II, and III. The repeated plume types represent the shape of the current plume. Step 10: The area between the two straight lines generated in Step 8 is the search range for pollution sources by the planar UAV.

2. The method for determining plume type and defining the search range for pollution sources according to claim 1, characterized in that... Step 3 involves comparing the vertical lapse rate of air temperature with the vertical lapse rate of dry adiabatic conditions to determine the plume type. The determination is based on the following criteria: (1) If γ is first greater than 0 and then greater than γ d If the value is less than 0, the plume type is smoke plume. (2) If γ is always greater than 0 and greater than γ d Then the plume type is wavy; (3) If γ is always greater than 0 and less than γ d Then the plume type is conical; (4) If γ is always less than 0, then the plume type is flat; (5) If γ is first less than 0 and then greater than 0, the plume type is climbing type.

3. The method for determining plume type and defining the search range for pollution sources according to claim 1, characterized in that... In step 6, the plume type is determined based on the overall trend of plume width variation and the slope of the fitted line at the midpoint. The determination criteria are as follows: (1) If the overall trend of plume width is from small to large but there are occasional alternations in size, then the plume type is wavy. (2) If the plume width increases from small to large, the plume type is conical, climbing, or smoke-filled. Calculate P. i1 (x i1 y i1 ), P i2 (x i2 y i2 midpoint Connect the lines and fit a straight line with slope k1. Compare k1 with tanθ, where θ is the set angle: (2.1) If k1 is greater than tanθ, then the plume type is ascending type; (2.2) If k1 is less than -tanθ, then the plume type is smoke type; (2.3) If k1 is less than tanθ and greater than -tanθ, then the plume type is conical; (3) If the width of the plume does not change significantly, the plume type is flat.

4. The method for determining plume type and defining the search range for pollution sources according to claim 1, characterized in that... Step 8 involves comparing the slopes of the upper and lower boundaries with tanα to determine the shape of the plume, where the slope of the upper boundary is k2, the slope of the lower boundary is k3, and α is a set angle. The determination is based on the following criteria: (1) If both k2 and k3 are greater than tanα, then the plume type is wavy; (2) If k2 is greater than tanα and k3 is greater than 0 and less than tanα, then the plume type is ascending type; (3) If k2 is greater than 0 and less than tanα, and k3 is less than -tanα, then the plume type is smoke type; (4) If k2 is greater than tanα and k3 is less than -tanα, then the plume type is conical; (5) If the absolute values ​​of k2 and k3 are both less than tanα, then the plume type is flat.

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