Center of gravity measuring device and method for measuring center of gravity of unmanned aerial vehicle

Abstract

The present application relates to a center of gravity measuring device and a method for measuring the center of gravity of a drone. The center of gravity measuring device includes: a platform scale; a bracket, which is movably arranged on the platform scale, and the bracket includes a bottom plate, a support plate and a top plate, one end of the support plate is connected to the bottom plate, and the other end of the support plate is connected to the top plate; a support block, which is arranged on the upper surface of the top plate; an ejector pin, which is movably arranged on the support block; a plumb bob, which is suspended on the top plate, and when the bracket is in a horizontal state, the bottom end of the plumb bob is aligned with the center of the bottom plate. The center of gravity measuring device of the present application has a simple structure, does not require high flatness of the use site, and can measure accurately.

Description

Technical Field

[0001] The present application relates to the field of drone detection, and in particular to a center of gravity measuring device and a method for measuring the center of gravity of a drone. Background Art

[0002] In the process of UAV flight control design and aircraft performance design, accurate data of the center of gravity of the UAV is required, which plays a critical role in the flight control and safety of the UAV. There are some problems with the current UAV center of gravity measurement device, such as: precise structure, high requirements for the site and environment; large weight and volume, not easy to carry, and long preparation time; most weighing devices are special devices and are not universally applicable; generally only the X-axis and Y-axis center of gravity positions can be measured, and the Z-axis center of gravity position is not easy to measure. Summary of the invention

[0003] Based on the above problems, the present application provides a center of gravity measuring device and a method for measuring the center of gravity of a drone. The center of gravity measuring device has a simple structure and is easy to use.

[0004] An embodiment of the present application provides a center of gravity measuring device, including: a platform scale; a bracket, movably arranged on the platform scale, the bracket including a base plate, a support plate and a top plate, one end of the support plate is connected to the base plate, and the other end of the support plate is connected to the top plate; a support block, arranged on the upper surface of the top plate; a pin, movably arranged on the support block; a plumb bob suspended on the top plate, and when the bracket is in a horizontal state, the bottom end of the plumb bob is aligned with the center of the base plate.

[0005] According to some embodiments of the present application, a level is provided on the top plate of the bracket.

[0006] According to some embodiments of the present application, the upper surface of the bottom plate of the bracket is provided with a plurality of concentric circles with the center of the bottom plate as the center.

[0007] According to some embodiments of the present application, the ejector pin is threadedly connected to the support block.

[0008] According to some embodiments of the present application, the platform scale includes: a platform portion for weighing; and a plurality of height-adjustable legs disposed below the platform portion.

[0009] An embodiment of the present application provides a method for measuring the center of gravity of a drone using the center of gravity measuring device as described above, wherein the drone includes n weight detection points, 3≤n≤6, and the method includes: respectively arranging n platform scales below the weight detection points of the drone; placing the bracket on the platform scale and adjusting the bracket to a horizontal state; placing the drone on the ejector pin and adjusting the ejector pin to make the drone in a horizontal state; establishing a coordinate system and determining the coordinates of the tips of the n ejector pins in the coordinate system; and determining the center of gravity of the drone based on the weight values ​​of the drone measured by the n platform scales and the coordinates of the n ejector pins.

[0010] According to some embodiments of the present application, the establishment of a coordinate system and the determination of the coordinates of the tips of the n ejector pins in the coordinate system include: taking the fuselage coordinate origin when designing the drone as the origin of the coordinate system; determining that the coordinates of the centers of the bottom plates of the n brackets in the X and Y directions are (a1, b1), (a2, b2) ... (an, bn), respectively, the height of the bracket is L, the distances from the centers of the bottom plates of the n brackets to the corresponding ejector pins are d1, d2, ... dn, respectively, the coordinates of the points on the bottom plate corresponding to the n plumbs in the X and Y directions are (e1, f1), (e2, f2), ... (en, fn), respectively, and the height distance between the lowest point of the drone and the top surface of the platform scale is Δz; the coordinates of the tips of the n ejector pins (xi, yi, zi) are:

[0011] xi=(ei-ai) / L×di+ai

[0012] yi=(fi-bi) / L×di+bi

[0013] zi=sin(arccos((ei-ai) / L)°)×di-Δz, where 1≤i≤n.

[0014] According to some embodiments of the present application, determining the center of gravity of the drone according to the weight values ​​of the drone measured by the n platform scales and the coordinates of the n ejectors includes: determining that the weight values ​​of the drone measured by the n platform scales are W1, W2, ... Wn respectively; the coordinates (X, Y, Z) of the center of gravity of the drone are:

[0015] X=(W1×x1+W2×x2+……Wn×xn) / (W1+W2+……Wn)

[0016] Y=(W1×y1+W2×y2+……Wn×yn) / (W1+W2+……Wn)

[0017] Z=(W1×z1+W2×z2+…Wn×zn) / (W1+W2+…Wn).

[0018] According to some embodiments of the present application, when a level is provided on the top plate of the bracket, adjusting the bracket to a horizontal state includes: determining whether the bracket is in a horizontal state by using the level.

[0019] The center of gravity measuring device of the present application has a simple structure, does not require high flatness of the site of use, and can measure accurately; the number of center of gravity measuring devices used can be selected according to demand, and only leveling operation is required before use, and the preparation time is short; it can accurately measure the position of the center of gravity of the drone on the Z axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without exceeding the scope of protection required by the present application.

[0021] Figure 1 is a schematic diagram of a center of gravity measuring device according to an embodiment of the present application;

[0022] Figure 2 is a top view of a gravity center measuring device according to an embodiment of the present application;

[0023] Figure 3 is a schematic diagram of a platform scale according to an embodiment of the present application;

[0024] Figure 4 is a schematic diagram of an ejector pin according to an embodiment of the present application;

[0025] Figure 5 is a schematic diagram of a plumb bob according to an embodiment of the present application;

[0026] Figure 6 is a schematic diagram of a gravity center measurement device supporting a drone according to an embodiment of the present application;

[0027] Figure 7 It is a schematic diagram of measurement data when calculating the center of gravity in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The following is a clear and complete description of the technical solution of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0029] like Figure 1 and Figure 2As shown, this embodiment provides a gravity center measuring device 100 for measuring the gravity center position of a drone. The gravity center measuring device 100 includes a platform scale 1, a bracket 2, a support block 3, a thimble 4 and a plumb bob 5.

[0030] like Figure 3 As shown, the platform scale 1 can use an existing electronic scale, and the platform scale 1 can display the weight of the object on the platform scale in real time. The platform scale 1 includes a platform portion 11 and a plurality of legs 12, and the height of the legs 12 is adjustable. The platform portion 11 is used for weighing. Optionally, the legs 12 use existing legs with adjustable height. In this embodiment, the plurality of legs 12 are respectively arranged at the four corners of the bottom surface of the platform portion to provide stable support for the platform scale 1. The legs 12 can be used to level the platform scale 1.

[0031] The bracket 2 is arranged on the platform scale 1. The bracket 2 and the platform scale 1 are separate structures. When in use, the bracket 2 is placed on the platform scale 1. When not in use, the bracket 2 can be moved away from the platform scale 1.

[0032] The bracket 2 includes a bottom plate 21, a support plate 22 and a top plate 23. One end of the support plate 22 is connected to the bottom plate 21, and the other end of the support plate 22 is connected to the top plate 23, and the support plate 22 supports the top plate 23. The bottom plate 21 and the top plate 23 in this embodiment are both circular, and the bottom plate 21 and the top plate 23 are made of thin plates. When calculating the center of gravity of the drone, the bottom plate 21 and the top plate 23 can be simplified into planes. Taking the bottom plate 21 as an example, after simplifying the bottom plate 21 into a plane, the center of the upper surface of the bottom plate 21 and the center of the lower surface coincide with each other, which serves as the center of the bottom plate 21. The number of the support plates 22 can be multiple, and the multiple support plates 22 are evenly distributed around the axis of the bracket 2.

[0033] The support block 3 is fixedly arranged on the upper surface of the top plate 23. In this embodiment, the axis of the support block 3 is colinear with the axis of the bracket 2. Optionally, the shape of the support block 3 is a truncated cone.

[0034] like Figure 4 As shown, the ejector pin 4 is movably arranged on the support block 3. When in use, the ejector pin 4 is used to provide support to the drone, and the position of the ejector pin 4 can be adjusted up and down, so that the ejector pin 4 can support the drone.

[0035] like Figure 5 As shown, the plumb bob 5 is suspended at the center of the top plate 23 by a suspension rope. When the bracket 2 is in a horizontal state, the bottom end of the plumb bob 52 is aligned with the center of the bottom plate 21.

[0036] like Figure 6 As shown, the drone 200 is provided with multiple weight detection points, and the number of weight detection points is usually more than 3. A center of gravity measuring device 100 is arranged below each weight detection point, and the center of gravity of the drone 200 is measured by the cooperation of multiple center of gravity measuring devices 100.

[0037] According to an optional technical solution of the present application, a level 24 is provided on the upper surface of the top plate 23 of the bracket 2. Optionally, the level 24 is a bubble level. The surveyor can determine whether the bracket 2 is in a horizontal state through the level 24. After the bracket 2 is placed on the platform scale 1, if the bracket 2 is not in a horizontal state, the support legs 12 can be adjusted to make the bracket 2 in a horizontal state. When the bracket 2 is in a horizontal state, the bottom end of the plumb bob 52 is aligned with the center of the bottom plate 21.

[0038] According to an optional technical solution of the present application, the upper surface of the bottom plate 21 of the bracket 2 is provided with a plurality of concentric circles with the center of the bottom plate 21 as the center. A plurality of concentric circles are provided on the upper surface of the bottom plate 22, so that if the bracket tilts, it is convenient for the measurement personnel to know the degree of tilt of the bracket 2.

[0039] According to an optional technical solution of the present application, the ejector pin 4 is threadedly connected to the support block 3. The ejector pin 4 is provided with a screw rod, and the upper surface of the support block 3 is provided with a threaded hole adapted to the screw rod. By rotating the ejector pin 4, the height of the tip of the ejector pin 4 relative to the center of the bottom plate 21 can be adjusted.

[0040] like Figure 7 As shown, Figure 7 The dotted line in the figure represents the drone. The inventor found that the bottom plate 21 of the bracket 2 is circular. When the center of gravity of the drone 200 is measured by the cooperation of multiple center of gravity measuring devices 100, after the drone 200 is placed on the ejector pin 4, the tops of the multiple center of gravity measuring devices 100 will be slightly tilted outward. The tilt of the multiple center of gravity measuring devices 100 is almost impossible to observe with the naked eye, but it will affect the measurement accuracy of the center of gravity of the drone.

[0041] This embodiment provides a method for measuring the center of gravity of a drone 200 using the above center of gravity measuring device 100. The drone 200 includes n weight detection points, 3≤n≤6. The weight detection points are positions preset when designing the drone for detecting the weight of the drone. Figure 6 As shown, the drone includes 4 weight detection points.

[0042] The method for measuring the center of gravity of the drone 200 comprises the steps of:

[0043] S1. Set n platform scales 1 below the weight detection points of the drone respectively.

[0044] A center of gravity measuring device is correspondingly arranged below the weight detection point of each drone, and the platform scale 1 of the center of gravity measuring device needs to be placed below the weight detection point. Optionally, the platform scale 1 is roughly in a horizontal state by adjusting the legs 12.

[0045] S2. Place the bracket on the platform scale and adjust the bracket to a horizontal state.

[0046] Place the bracket 2 on the corresponding platform scale 1, and adjust the legs 12 so that the bracket 2 is in a horizontal state. Adjust the ejector pin 4 on the bracket 2 to the lowest height.

[0047] Optionally, when a level meter 24 is provided on the top plate 23 of the bracket, the level meter 24 is used to determine whether the bracket 2 is in a horizontal state.

[0048] S3, placing the drone 200 on the ejector pin 4, the ejector pin 4 supports the weight detection point of the drone 200, and adjusting the height of the ejector pin 4 to make the drone 200 in a horizontal state. Whether the drone 200 is in a horizontal state can be detected by existing methods.

[0049] S4. Establish a coordinate system and determine the coordinates of the tips of the n ejector pins 4 in the coordinate system.

[0050] Optionally, the fuselage coordinate origin when designing the drone is used as the origin of the coordinate system. Other coordinate systems can also be established as needed.

[0051] S5. Determine the center of gravity of the drone according to the weight values ​​of the drone measured by the n platform scales and the coordinates of the n ejector pins.

[0052] Optionally, step S4 includes:

[0053] S41, the fuselage coordinate origin when designing the drone is used as the origin of the coordinate system, wherein the horizontal direction parallel to the axis of the drone is the X direction, the horizontal direction perpendicular to the axis of the drone is the Y direction, and the vertical direction is the Z direction.

[0054] S42. Determine that the coordinates of the center of the bottom plate of the n brackets in the X and Y directions are (a1, b1), (a2, b2) ... (an, bn), the height of the bracket is L, the distances from the center of the bottom plate of the n brackets to the corresponding ejector pins are d1, d2, ... dn, the coordinates of the points on the bottom plate corresponding to the n plumb bobs in the X and Y directions are (e1, f1), (e2, f2), ... (en, fn), and the height distance between the lowest point of the drone and the top surface of the platform scale is Δz. The above values ​​can all be measured by instruments.

[0055] The bottom plates 21 and 23 of the bracket 2 are simplified into planes. The drone of this embodiment includes four weight detection points. The coordinates of the centers of the bottom plates of the four brackets in the X and Y directions are determined to be (a1, b1), (a2, b2), (a3, b3), and (a4, b4), respectively.

[0056] The height of the bracket is L.

[0057] The distances from the center of the bottom plate of the four brackets to the corresponding ejector pins are d1, d2, d3, and d4 respectively.

[0058] The coordinates of the points on the bottom plate corresponding to the four plumb bobs in the X and Y directions are (e1, f1), (e2, f2), (e3, f3), and (e4, f4).

[0059] The height distance between the lowest point of the drone and the top surface of the platform scale is Δz.

[0060] S3. The coordinates (xi, yi, zi) of the tips of the n ejector pins are:

[0061] xi=(ei-ai) / L×di+ai

[0062] yi=(fi-bi) / L×di+bi

[0063] zi=sin(arccos((ei-ai) / L)°)×di-Δz, where 1≤i≤n.

[0064] In this embodiment, the coordinates (x1, y1, z1) of the tip of the first ejector pin are:

[0065] X1=(e1-a1) / L×d1+a1

[0066] Y1=(f1-b1) / L×d1+b1

[0067] Z1=sin(arccos((ei-ai) / L)°)×d1-Δz,

[0068] Repeat the above calculation to obtain the coordinates of the tips of the remaining three ejector pins (x2, y2, z2), (x3, y3, z3) and (x4, y4, z4).

[0069] Optionally, determining the center of the drone according to the weight values ​​measured by n platform scales and the coordinates of n ejectors includes: determining that the weight values ​​measured by the n platform scales are W1, W2, ... Wn respectively; the coordinates (X, Y, Z) of the center of gravity of the drone are:

[0070] X=(W1×x1+W2×x2+……Wn×xn) / (W1+W2+……Wn)

[0071] Y=(W1×y1+W2×y2+……Wn×yn) / (W1+W2+……Wn)

[0072] Z=(W1×z1+W2×z2+…Wn×zn) / (W1+W2+…Wn).

[0073] In this embodiment, the weight values ​​measured by the four platform scales are determined to be W1, W2, W3, and W4, respectively, and the coordinates (X, Y, Z) of the center of gravity of the drone are:

[0074] X=(W1×x1+W2×x2+W3×x3+W4×x4) / (W1+W2+W3+W4)

[0075] Y=(W1×y1+W2×y2+W3×y3+W4×y4) / (W1+W2+W3+W4)

[0076] Z=(W1×z1+W2×z2+W3×z3+W4×z4) / (W1+W2+W3+W4).

[0077] The center of gravity measuring device of the present application has a simple structure, does not require high flatness of the site of use, and can measure accurately; the platform scale and the bracket are split, and different quantities can be selected for combination according to different needs, which is convenient to carry. Only leveling operation is required before use, and the preparation time is very short; the pin contact method is adopted, and most of the surfaces can be used as support points, which has universal applicability.

[0078] The embodiments of the present application are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and core ideas of the present application. Therefore, changes or deformations made by those skilled in the art based on the ideas of the present application, the specific implementation methods and the scope of application of the present application, all belong to the scope of protection of the present application. In summary, the contents of this specification should not be construed as limiting the present application.

Claims

1. A center of gravity measuring device, characterized in that: include: The platform said; A bracket is movably arranged on the platform scale, the bracket comprising a bottom plate, a support plate and a top plate, one end of the support plate is connected to the bottom plate, and the other end of the support plate is connected to the top plate; a plurality of concentric circles with the center of the bottom plate as the center are arranged on the upper surface of the bottom plate of the bracket; A support block, arranged on the upper surface of the top plate; An ejector pin is movably disposed on the support block; A plumb bob is hung on the top plate. When the bracket is in a horizontal state, the bottom end of the plumb bob is aligned with the center of the bottom plate. The plumb bob is used to indicate whether the bracket is tilted.

2. The center of gravity measuring device according to claim 1, characterized in that: A level is arranged on the top plate of the bracket.

3. The center of gravity measuring device according to claim 1, characterized in that: The ejector pin is threadedly connected to the support block.

4. The center of gravity measuring device according to claim 1, characterized in that: The platform is said to include: The platform part is used for weighing; A plurality of height-adjustable legs are arranged below the platform portion.

5. A method for measuring the center of gravity of a drone using the center of gravity measuring device according to any one of claims 1 to 4, wherein the drone comprises n weight detection points, 3≤n≤6, and wherein: The method comprises: The n platform scales are respectively arranged below the weight detection points of the drone; Placing the bracket on the platform scale and adjusting the bracket to a horizontal state; Placing the drone on the ejector pin, and adjusting the ejector pin to keep the drone in a horizontal state; Establishing a coordinate system, and determining the coordinates of the tips of the n ejector pins in the coordinate system; Determining the center of gravity of the drone according to the weight values ​​of the drone measured by the n platform scales and the coordinates of the n ejectors; The step of establishing a coordinate system and determining the coordinates of the tips of the n ejector pins in the coordinate system includes: The fuselage coordinate origin when designing the UAV is taken as the origin of the coordinate system; Determine that the coordinates of the centers of the bottom plates of the n brackets in the X and Y directions are (a1, b1), (a2, b2) ... (an, bn), the height of the bracket is L, the distances from the centers of the bottom plates of the n brackets to the corresponding ejector pins are d1, d2, ... dn, the coordinates of the points on the bottom plate corresponding to the n plumb bobs in the X and Y directions are (e1, f1), (e2, f2), ... (en, fn), and the height distance between the lowest point of the drone and the top surface of the platform scale is Δz; The coordinates (xi, yi, zi) of the tips of the n ejector pins are: xi=(ei-ai) / L×di+ai yi=(fi-bi) / L×di+bi zi=sin(arccos((ei-ai) / L)°)×di-Δz, where 1≤i≤n.

6. The method according to claim 5, characterized in that The determining the center of gravity of the drone according to the weight values ​​of the drone weighed by the n platform scales and the coordinates of the n ejector pins comprises: Determine the weight values ​​of the drones weighed by the n platform scales as W1, W2, ..., Wn respectively; The coordinates (X, Y, Z) of the center of gravity of the drone are: X=(W1×x1+W2×x2+……Wn×xn) / (W1+W2+……Wn) Y=(W1×y1+W2×y2+……Wn×yn) / (W1+W2+……Wn) Z=(W1×z1+W2×z2+…Wn×zn) / (W1+W2+…Wn).

7. The method according to claim 5, characterized in that When a level is provided on the top plate of the bracket, adjusting the bracket to a horizontal state includes: determining whether the bracket is in a horizontal state by using the level.

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