An oil-driven unmanned helicopter-based ground-simulating route planning method

Abstract

The application provides a ground-simulating route planning method based on an oil-driven unmanned helicopter, and comprises the following steps: automatically planning an auxiliary route connecting two adjacent survey routes according to given survey route endpoints and unmanned helicopter flight dynamics constraints; and generating several height-available task route segments by using a comprehensive route smoothing algorithm according to terrain height data under the task route. The comprehensive route smoothing algorithm comprises a slope limiting smoothing algorithm, a curvature smoothing algorithm and a waypoint clipping algorithm. The route planning method is integrated in unmanned helicopter ground control software, improves the intelligent level of the oil-driven unmanned helicopter system, reduces the planning difficulty of the operator, and has high engineering application value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil-powered unmanned helicopter route planning, and particularly relates to a ground-imitating route planning method based on an oil-powered unmanned helicopter. BACKGROUND

[0002] To effectively realize autonomous flight of an unmanned helicopter, automatically complete a flight task, one of the core supports is route planning. Meanwhile, the intelligent level of route planning is also a reflection of the intelligent level of unmanned helicopter control. Traditional route planning can be divided into manual planning based on a task scenario and automatic planning based on an intelligent algorithm. Manual planning has the problems of large planning task amount and complex planning. Automatic planning based on an intelligent algorithm is usually planning for terrain features. In terms of ground-imitating route planning for a terrain detection task using an oil-powered unmanned helicopter, there is currently a lack of effective and referenceable methods for route planning in this task scenario.

[0003] An industrial oil-powered unmanned helicopter has higher requirements for flight safety and flight route accuracy and rationality when performing a task. When planning a flight route, the type of flight task to be performed and the task load carried need to be considered comprehensively. When an oil-powered unmanned helicopter is used for a terrain detection task, the planning of the flight route of the aircraft involves analysis of the flight dynamics characteristics of the unmanned helicopter, acquisition of elevation data in a digital elevation model (DEM) under the flight route, slope smoothing, curvature smoothing, and redundant point pruning. Therefore, the professional requirements for the operator of the oil-powered unmanned helicopter are high. Due to the high professional requirements for the operator, the intelligent level is low, and due to the uncertainty of the human factor, it is difficult to plan a reasonable and efficient flight route. SUMMARY

[0004] The present application aims to improve the accuracy and convenience of route planning by ground operators, and provides a ground-imitating route planning method based on an oil-powered unmanned helicopter, comprising the following steps:

[0005] Step 1, generating a task route: obtaining elevation data in a digital elevation model (DEM) under the survey line, lifting the elevation data in the digital elevation model (DEM) under the survey line as a whole to generate a route with a specified height above ground; obtaining the maximum available slope of the oil-powered unmanned helicopter at the task flight speed, using a slope limiting smoothing algorithm to limit the slope of the route, and limiting the slope of the route within the maximum available slope of the helicopter; obtaining the maximum available normal overload of the oil-powered unmanned helicopter at the task flight speed, and using a curvature smoothing algorithm to smooth the slope-limited route to limit the curvature of the route within the maximum normal overload of the helicopter; the height of the route points after slope and curvature smoothing is still frequently fluctuating, and the distance between the route points is the sampling distance in the digital elevation model (DEM), which does not meet the flight route requirements, so the route points after slope and curvature smoothing need to be trimmed to generate a task route for the unmanned helicopter.

[0006] Step 2, generating an auxiliary route: automatically generating an auxiliary route connecting two adjacent survey lines according to the given survey line endpoints;

[0007] Step 3, judging the minimum height above ground.

[0008] Step 1 includes:

[0009] Step 1-1, executing a slope limiting smoothing algorithm; according to the longitudinal vertical maneuvering capability of the oil-powered unmanned helicopter, the unmanned helicopter has a maximum track climb and dive angle limit, obtaining the maximum track climb and dive angle of the unmanned helicopter at the task flight speed, and limiting the slope of the route, when the slope of the route point exceeds the limited positive or negative slope, the slope limiting smoothing algorithm is used to adjust the route point.

[0010] Step 1-2, executing a curvature smoothing algorithm;

[0011] Step 1-3, point trimming: trimming the redundant route points after slope and curvature smoothing to generate a task route for the oil-powered unmanned helicopter.

[0012] In step 1-1, first calculate the slope value of each point of the route, then limit the slope of the route so that the slope of the route does not exceed the maximum positive slope and the maximum negative slope;

[0013] The terrain elevation along the entire flight route is lifted as a whole to the ground effect flight height to obtain a route sequence, wherein the height of the i-th point is h i , i = 1, 2, 3, …, N, N is the total number of route points, and the slope k i of the i-th route point is:

[0014] k i =(h i -h i-1 ) / dx

[0015] wherein dx is the horizontal distance between the waypoints of the route;

[0016] Let the maximum allowable slope of the route be k max , k max is positive, and k max is defined as:

[0017] k max =tan(γ max )

[0018] wherein γ max is the maximum allowable flight path climb angle of the unmanned helicopter for terrain following, and γ max is positive;

[0019] Let the minimum allowable slope of the route be k min , k min is negative, and k min is defined as:

[0020] k min =tan(γ min )

[0021] wherein γ min is the minimum allowable flight path climb angle of the unmanned helicopter for terrain following, and γ min is negative;

[0022] Adjust the slope of each waypoint, which specifically includes two cases of positive slope smoothing and negative slope smoothing:

[0023] Positive slope smoothing: if k i >k max , the slope of the ith waypoint must be reduced to k max , according to the slope formula and the principle of raising the route waypoint as much as possible, h i-1 needs to be increased at this time, and the amount of increase Δh i-1 is:

[0024] Δh i-1 =h i -h i-1 -k max *dx

[0025] The height of the adjusted (i-1)th waypoint is:

[0026] h i-1 =h i-1 +Δh i-1

[0027] Check if k i-x is less than k max , if not, increase the height of the i-2 waypoint, and recursively increase the height of the waypoints from right to left until the slope of all waypoints is less than the maximum slope allowed value k max .

[0028] Negative slope smoothing: if k i < k min , increase the slope of the i waypoint to k min , according to the slope formula and the principle of trying to raise the height of the waypoints of the route, at this time, increase h i , increase the amount Δh i :

[0029] Δh i = -h i + h i-1 + k min * dx

[0030] The height h i of the i waypoint after adjustment is:

[0031] h i = h i + Δh i

[0032] Check if k i+1 is greater than k min , if not, increase the height of the i+1 waypoint, and recursively increase the height of the waypoints from left to right until the slope of all waypoints is greater than the minimum slope allowed value k min .

[0033] Step 1-2 includes: using Gaussian convolution to smooth the height of the route:

[0034] The one-dimensional Gaussian function f(x) is in the form of:

[0035]

[0036] Where σ is the scale factor; k is the proportion factor, used to adjust the overall height of the route; e is the natural constant; x is the height of the waypoint; μ is the mean of the height of the waypoint.

[0037] Step 1-2 also includes: calculating the Gaussian convolution template from the Gaussian function, convolving the Gaussian convolution template with the route after slope smoothing, and smoothing the height data of the route. After one convolution smoothing, the curvature of each point of the processed route is calculated, and if the curvature value exceeds the normal overload limit of the unmanned helicopter at the task speed, the convolution is continued until the curvature of all points is within the limit.

[0038] The steps 1-3 include: forming a route segment with N consecutive waypoints; forming a second route segment with subsequent N consecutive waypoints, and sequentially dividing the whole route into several route segments;

[0039] For each route segment, the maximum height h of the waypoints is calculated max And the minimum height h min The deviation Ah of the maximum height and the minimum height is calculated err :

[0040] Ah err = h max -h min

[0041] If Ah err is less than the height difference under the required or limited slope of the planned route, the first point and the last point of the route segment are taken as the starting point and the ending point of the route segment, and the remaining waypoints in the middle are removed.

[0042] The step 2 includes: obtaining the turning radius R of the oil-powered unmanned helicopter at the task speed, and the interval L between the adjacent two survey lines.

[0043] If L is greater than or equal to 2R, the two end points 1 and 2 of the survey line are adjusted to be flush, and the turning radius R is extended forward to generate new auxiliary waypoints a and b, and then the auxiliary route segments 1-a, a-b and b-2 are generated.

[0044] If L is less than 2R, the two end points of the survey line are adjusted to be flush, and the auxiliary route is generated along the direction deviated by 135 degrees from the survey line direction, and new auxiliary waypoints a, b, c, d and e are generated, and the route a-b, b-c, c-d and d-e are automatically generated according to the generated rectangular route rule.

[0045] The step 3 includes: performing the route minimum ground height detection on the planned task segment route and the auxiliary segment route, and the route minimum ground height is determined by the oil-powered unmanned helicopter system; if a waypoint is lower than the minimum ground height, the whole route is lifted to the minimum safe height.

[0046] The application also provides an electronic device including a processor and a memory, wherein the memory stores program codes, and when the program codes are executed by the processor, the processor executes the steps of the method.

[0047] The application also provides a storage medium storing computer programs or instructions, and when the computer programs or instructions are run on a computer, the steps of the method are executed.

[0048] Beneficial effects: (1) a route planning method based on the oil-powered unmanned helicopter performing the terrain detection task and the ground effect flight is provided;

[0049] (2) It will effectively improve the accuracy and rationality of route planning and reduce the planning difficulty for operators, thereby improving the intelligence level of unmanned helicopter systems. Attached Figure Description

[0050] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0051] Figure 1 This is a schematic diagram of the method and process for planning the terrain-following flight path for terrain reconnaissance missions using gasoline-powered unmanned helicopters.

[0052] Figure 2 This is a schematic diagram illustrating the principle of the route planning method for terrain reconnaissance missions and terrain-following flight missions of gasoline-powered unmanned helicopters.

[0053] Figure 3 A schematic diagram for generating auxiliary flight paths between adjacent survey lines (L>=2R).

[0054] Figure 4 A schematic diagram for generating auxiliary flight paths between adjacent survey lines (L<2R).

[0055] Figure 5 The following are renderings of the route planning stages in Example 1.

[0056] Figure 6 This is a diagram showing the route planning results of Example 1.

[0057] Figure 7 The following are renderings of the route planning stages in Example 2.

[0058] Figure 8 This is a diagram showing the route planning results of Example 2. Detailed Implementation

[0059] This invention provides a method for terrain-following flight path planning based on a gasoline-powered unmanned helicopter. The overall planning flowchart of this method is as follows: Figure 1 As shown. Input the endpoint positions of two points on each survey line, the distance between adjacent survey lines, and the terrain-following flight altitude. For a single survey line, a comprehensive flight path smoothing planning algorithm is applied to plan the mission segment flight path; for two adjacent survey lines, an auxiliary flight path connecting the two survey lines is automatically generated based on the relationship between the distance between the survey lines and the turning radius of the unmanned helicopter.

[0060] like Figure 2 , Figure 3 , Figure 4 As shown, the method specifically includes:

[0061] Step 1, Integrated route smoothing planning for the task segment;

[0062] (1) Slope-constrained smoothing algorithm;

[0063] According to the longitudinal and vertical maneuvering capability of the oil-driven unmanned helicopter, the unmanned helicopter has a maximum track climb and dive angle limit. The maximum track climb and dive angle of the unmanned helicopter at the task flight speed is obtained to limit the slope of the route. When the slope of the route waypoint exceeds the limited positive or negative slope, the slope limiting smoothing algorithm is used to adjust the route waypoint.

[0064] The basic idea of the slope limiting smoothing algorithm is: first, the slope value of each point of the route is calculated; then the slope of the route is limited so as not to exceed the maximum positive and negative slope. The two slope limiting values are set according to the longitudinal and vertical maneuvering performance of the unmanned helicopter.

[0065] The terrain elevation along the entire flight route is lifted to the terrain following height to obtain a route sequence, the height of the i-th waypoint is h i (i = 1, 2, 3, …, N), N is the total number of route waypoints. The slope corresponding to the i-th point is:

[0066] k i =(h i -h i-1 ) / dx

[0067] Where dx is the horizontal distance between the route waypoints.

[0068] The maximum slope allowed by the route is denoted as h max , k max is positive, and k max is defined as follows:

[0069] k max =tan(γ max )

[0070] Where γ max is the maximum track climb angle allowed by the unmanned helicopter for terrain following, and γ max is positive.

[0071] The minimum slope allowed by the route is denoted as k min , k min is negative, and k min is defined as follows:

[0072] k min =tan(γ min )

[0073] Where γ min is the minimum track climb angle allowed by the unmanned helicopter for terrain following, and γ min is negative.

[0074] Adjust the slope of each waypoint, which is further divided into two cases:

[0075] Positive slope smoothing:

[0076] If k i > k max , the slope of the ith waypoint must be reduced to k max . According to the slope formula and the principle of raising the height of the waypoints of the flight path as much as possible, h i-1 must be increased by an amount Δh i-1 , which is:

[0077] Δh i-1 = h i - h i-1 - k max * dx

[0078] The height of the ith-1 waypoint after adjustment is:

[0079] h i-1 = h i-1 + Δh i-1

[0080] h i-1 is increased and k i is reduced, but k i-1 is also increased. At this time, it is necessary to check whether k i-1 is less than k max . If not, the height of the ith-2 waypoint must be increased, and the process is recursively performed from right to left until the slope of all waypoints is less than the maximum slope allowed value k max .

[0081] Negative slope smoothing:

[0082] If k i < k min , the slope of the ith waypoint must be increased to k min . According to the slope formula and the principle of raising the height of the waypoints of the flight path as much as possible, h i must be increased by an amount Δh i , which is:

[0083] Δh i = -h i + h i-1 + k min * dx

[0084] The height of the ith waypoint after adjustment is:

[0085] h i = h i + Δh i

[0086] h i is increased and k i , but ki+1 But at the same time, it is reduced, at this time need to check k i+1 Whether greater than k min , if not, must increase the height of the i+1 waypoint, from left to right recursively until all the slope of the waypoint is greater than the minimum slope of the allowable value k min .

[0087] After the above slope smoothing, the slope of the waypoint of the route k i Can meet the use requirements, and the height increment of the route is minimum, which can be as close as possible to the original appearance of the terrain.

[0088] Because the positive slope smoothing is first performed from right to left, and then the negative slope smoothing is performed from left to right, when the positive slope smoothing is performed, the height of the left waypoint is adjusted, and when the negative slope smoothing is performed, the height of the right waypoint is adjusted, so the slope of the waypoint after the negative slope smoothing meets the positive slope requirement, and there is no need to perform the positive slope smoothing again.

[0089] (2) curvature smoothing algorithm;

[0090] Because the unmanned helicopter has a maximum normal overload limit, it is necessary to limit the maximum curvature of the route after limiting the slope of the route. The present scheme uses Gaussian convolution to smooth the height of the route.

[0091] The one-dimensional Gaussian function is as follows:

[0092]

[0093] In the formula, σ is a scale factor that can adjust the smoothing degree; k is a proportional factor that can adjust the overall height of the route; e is a natural constant; x is the height of the waypoint; and μ is the mean value of the height of the waypoint.

[0094] The Gaussian convolution template is calculated from the Gaussian function, and the Gaussian convolution template is convolved with the route after the slope smoothing, so as to smooth the height data of the route. After one convolution smoothing, the curvature of each point of the processed route is calculated, and if the curvature value exceeds the normal overload limit of the unmanned helicopter at the task speed, the convolution must be continued until the curvature of all points is within the limit range.

[0095] (3) waypoint pruning;

[0096] The height of the waypoint of the route after the slope and curvature smoothing is still frequently fluctuating, and the distance between the waypoints is still the sampling distance in the digital elevation model DEM, which does not meet the requirements of the flight route, so the redundant waypoint pruning is needed for the waypoint of the route after the slope and curvature smoothing to generate a task route that can be used by the unmanned helicopter.

[0097] First, a line segment is formed by N consecutive waypoints; then a second line segment is formed by the next N consecutive waypoints, and so on to divide the entire route into several line segments.

[0098] For each line segment, the maximum and minimum height deviation of the waypoints is calculated err :

[0099] Δh err = h max -h min

[0100] If Δh err is less than the height difference under the required or limited slope of the planned route, the first point and the last point of the line segment are taken as the starting point and the ending point of the line segment, and the remaining waypoints in between are removed.

[0101] Step 2, generate auxiliary lines between survey lines;

[0102] Get the turning radius R of the oil-powered unmanned helicopter at the task speed, and the distance L between the adjacent two survey lines;

[0103] If L≥2R, as shown in Figure 3 , adjust the two end points of the survey line to be flush, and extend forward by the turning radius R to generate new auxiliary waypoints a and b, then generate the auxiliary line segments 1 to a, a to b, and b to 2.

[0104] If L<2R, as shown in Figure 4 , adjust the two end points of the survey line to be flush, and generate an auxiliary line in the direction deviated by 135° from the survey line direction, to generate new auxiliary waypoints a, b, c, d, and e, and automatically generate the lines a to b, b to c, c to d, and d to e according to the generated rectangular line rule.

[0105] Step 3, determine the minimum ground clearance of the route;

[0106] Detect the minimum ground clearance of the planned task segment route and the auxiliary segment route, which is determined by the oil-powered unmanned helicopter system; if a waypoint is lower than the minimum ground clearance, the entire route is lifted by a corresponding distance.

[0107] In one embodiment of the present application, a survey line of an oil-powered unmanned helicopter in a certain field during a detection task is selected. Figure 5 The planning comparison graphs for each stage of the route planning process include the slope smoothing, curvature smoothing, and redundant waypoint pruning processes, respectively; and the height curve comparison effect with the original digital elevation model DEM in the survey line; Figure 6 The final result graph of the route planning is a comprehensive route smoothing and minimum ground clearance adjustment.

[0108] In another specific embodiment of the present application, different survey lines are selected for route planning illustration. Figure 7 For route planning process stage planning contrast map; Figure 8 For route planning final result map.

[0109] The present application provides a kind of oil-driven unmanned helicopter based on the method for ground route planning, the method and approach for specifically implementing this technical solution are many, the above-mentioned only is the preferred embodiment of the present application, it should be pointed out, for the ordinary skilled person in the art, without departing from the principle of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application. The components not explicitly described in the embodiment can be realized by existing technology.

Claims

1. A method for ground following path planning based on oil-powered unmanned helicopter, characterized in that, The method comprises the following steps: Step 1, generating a task route: obtaining elevation data in a digital elevation model DEM of the terrain below the survey line, lifting the elevation data in the digital elevation model DEM of the terrain below the survey line as a whole to a specified height above the ground to generate a route; obtaining the maximum available slope of the oil-powered unmanned helicopter at the task flight speed, using a slope limiting smoothing algorithm to limit the slope of the route, and limiting the slope of the route within the range of the maximum available slope of the helicopter; obtaining the maximum available normal overload of the oil-powered unmanned helicopter at the task flight speed, and using a curvature smoothing algorithm to smooth the slope-limited route to limit the curvature of the route within the range of the maximum normal overload of the helicopter; and performing redundant point pruning on the route points after slope smoothing and curvature smoothing to generate a task route available for the unmanned helicopter; Step 2, generating an auxiliary route: automatically generating an auxiliary route connecting two adjacent survey lines according to the given survey line endpoints; Step 3, performing a minimum height above ground judgment on the route points.

2. The method of claim 1, wherein, Step 1 comprises: Step 1-1, performing a slope limiting smoothing algorithm; according to the longitudinal vertical maneuvering capability of the oil-powered unmanned helicopter, the unmanned helicopter has a maximum track climb and dive angle limit, the maximum track climb and dive angle of the unmanned helicopter at the task flight speed is obtained to limit the slope of the route, and when the slope of the route point exceeds the limited positive or negative slope, the slope limiting smoothing algorithm is used to adjust the route point; Step 1-2, performing a curvature smoothing algorithm; Step 1-3, point pruning: performing redundant point pruning on the route points after slope smoothing and curvature smoothing to generate a task route for the oil-powered unmanned helicopter.

3. The method of claim 2, wherein, In step 1-1, the slope value of each point of the route is first calculated, and then the slope of the route is limited so that the slope of the route does not exceed the maximum positive slope and the maximum negative slope; The whole terrain elevation along the flight route is lifted to the ground effect flight height as a whole to obtain a route sequence, wherein the height of the ith waypoint is h i , i = 1, 2, 3,..., N, N is the total number of route waypoints, and the slope k i of the ith route waypoint is: k i = (h i - h i-1 ) / dx Wherein, dx is the horizontal distance between the route points; Let the maximum allowable slope of the route be denoted by k max , k max is positive, k max is defined as: k max = tan(γ max ) wherein γ max is the maximum allowed path climb angle for the terrain following by the unmanned helicopter, γ max is a positive value; Let the minimum slope allowed for the route be denoted by k min , k min is negative, k min is defined as: k min = tan(γ min ) wherein γ min is the minimum allowed path climb angle for the terrain following of the unmanned helicopter, γ min is negative; Adjusting the slope of each point, which includes two cases of positive slope smoothing and negative slope smoothing: Positive slope smoothing: if k i >k max Then the slope of the i-th waypoint must be reduced to k. max Based on the gradient formula and the principle of raising the waypoints as much as possible, h needs to be increased in this case. i-1 Increase the amount of Δh i-1 for: Δh i-1 = h i - h i-1 - k max * dx The height of the adjusted i-1th point is: h i-1 = h i-1 + Δh i-1 Check if k i-1 is less than k max If not, increase the height of the i-2 waypoint and recursively decrease the height of the subsequent waypoints until the slope of all waypoints is less than the maximum slope k max ; Negative slope smoothing: if k i < k min , then increase the slope of the ith waypoint to k min , according to the slope formula and the principle of trying to raise the route waypoint, at this time increase h i , increase the amount Δh i : Δh i = -h i + h i-1 + k min * dx adjusted height of the i-th waypoint h i is: h i = h i + Δh i Check if k i+1 is greater than k min If not, increase the height of the i+1 waypoint and recursively do the same from left to right until all the waypoints have a slope greater than the minimum slope allowed value k min .

4. The method of claim 3, wherein, Step 1-2 comprises: using Gaussian convolution to smooth the height of the route: The one-dimensional Gaussian function f(x) is in the form of: Wherein, σ is the scale factor; k is the proportion factor, which is used to adjust the overall height of the route; e is the natural constant; x is the height of the point; μ is the mean value of the height of the point.

5. The method of claim 4, wherein, Step 1-2 further comprises: calculating a Gaussian convolution template from the Gaussian function, convolving the Gaussian convolution template with the route after slope smoothing, and smoothing the height data of the route. After one convolution smoothing, the curvature of each point of the processed route is calculated, and if the curvature value exceeds the normal overload limit of the unmanned helicopter at the task speed, the convolution is continued until the curvature of all points is within the limit range.

6. The method of claim 5, wherein, Step 1-3 comprises: forming a route segment with N consecutive points; forming a second route segment with the next N consecutive points, and sequentially dividing the entire route into route segments; For each route segment, calculate the maximum waypoint altitude h. max and minimum value h min deviation Δh err : Δh err = h max - h min If Δh err If the height difference is less than the required or limited slope under the planned route, the first and last points of the route segment are taken as the starting point and the end point of the route segment, and the remaining intermediate waypoints are removed.

7. The method of claim 6, wherein, Step 2 comprises: obtaining the turning radius R of the oil-powered unmanned helicopter at the task speed, and the distance L between the adjacent two survey lines; If L≥2R, adjust the two end points 1 and 2 of the survey line to be flush, and rotate the forward extension disc by a radius R length to generate new auxiliary waypoints a and b, and then generate auxiliary line segments 1-a, a-b, and b-2. If L<2R, adjust the two end points of the survey line to be flush, and generate auxiliary lines in the direction deviated by 135° from the survey line direction to generate new auxiliary waypoints a, b, c, d, and e, and automatically generate lines a-b, b-c, c-d, and d-e according to the generated rectangular line rule.

8. The method of claim 7, wherein, Step 3 comprises: detecting the lowest ground clearance of the planned task segment line and the auxiliary segment line by the oil dynamic unmanned helicopter system; and if a waypoint is lower than the lowest ground clearance, the entire line is lifted to the lowest safety height.

9. An electronic device, comprising: A processor and a memory are included, and the memory stores program codes, which, when executed by the processor, cause the processor to perform the steps of the method of any one of claims 1 to 8.

10. A storage medium, characterized by A computer program or instructions are stored, which, when running on a computer, perform the steps of the method of any one of claims 1 to 8.

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