Centroid Measurement Method and Centroid Measurement Device

Abstract

This invention provides a method and device for measuring the center of mass. The method eliminates the need to suspend the object under test or apply various forces to it. The center of mass is measured by measuring the pressure exerted by the object on a supporting platform. The method is simple, has almost no requirements regarding the measurement environment or the shape of the object, has a wide range of applications, and provides accurate and reliable results. The device includes a base, measuring units, and a camera unit. Multiple measuring units are arranged along a first horizontal direction on the base, each forming a bearing area. The measuring units acquire the gravity F exerted by the object on the bearing area. The camera unit's lens faces the bearing platform to acquire the object's posture data. The method eliminates the need to suspend the object or apply various forces; the center of mass is measured by measuring the pressure exerted by the object on the bearing platform.

Description

Technical Field

[0001] This invention belongs to the field of centroid measurement technology, specifically relating to a centroid measurement method and a centroid measurement device. Background Technology

[0002] The center of mass, or CSM, is a hypothetical point on a material system where the mass is considered to be concentrated. The location of the CSM is of great significance in engineering. For example, to keep a crane stable, its CSM must meet certain conditions; the motion stability of aircraft, ships, and vehicles is also closely related to the CSM's location; furthermore, if the CSM of a high-speed rotating flywheel is not on its axis of rotation, it will cause severe vibrations, affecting the machine's normal operation and lifespan.

[0003] Currently, the main representative method for measuring the center of mass is the suspension method. The principle of the suspension method is that the perpendicular line through the suspension point of the object being measured must pass through the center of mass. Based on this principle, measurement can be performed using two suspension ropes, a marker plate, and a plumb bob. The specific operation is as follows: a center of mass beam is installed on the object to be measured, and two steel ropes are passed through the two center of mass beams and suspended from a single point, allowing them to hang naturally. The downward projection point of the suspension point must pass through the center of mass of the object being measured. By changing the suspension position multiple times, the spatial position of the center of mass can be determined. The measurement method is relatively simple.

[0004] However, the limitations of the suspension method cannot be ignored. For some irregular or smooth-surfaced objects, the operation of installing a centroid beam and other methods is relatively complicated, and the difficulty of suspending the object to be measured is very high, making the measurement process difficult to achieve. Summary of the Invention

[0005] This invention provides a method and apparatus for measuring the center of mass, aiming to solve the problem of the limitations of using the suspension method to measure the center of mass of an object.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] Firstly, a method for measuring the centroid is provided, comprising the following steps:

[0008] The support platform used to support the object under test is divided into multiple support areas distributed along the first horizontal direction;

[0009] A first attitude group is defined as at least two different attitudes that can be formed when the first side of the object under test contacts the support platform, and a second attitude group is defined as at least two different attitudes that can be formed when the second side of the object under test contacts the support platform.

[0010] Based on the gravity borne by each bearing area, multiple first spatial parallel force systems are formed along the vertical direction and respectively corresponding to multiple postures in the first posture group. For the same vertical reference plane, multiple first cutting planes are formed that are perpendicular to the vertical reference plane and contain the center of mass, corresponding to multiple postures in the first posture group. The first cutting plane is the plane that intersects the center plane of the first spatial parallel force system with the object to be measured. The vertical reference plane is parallel to the first horizontal direction, and the center plane of the first spatial parallel force system is perpendicular to the vertical reference plane.

[0011] The intersection line of multiple first cutting planes corresponding to different first spatial parallel force systems is the first centroid line. The first centroid line is perpendicular to the first side of the object under test and parallel to the vertical reference plane.

[0012] Based on the gravity borne by each bearing area, multiple second spatial parallel force systems are formed along the vertical direction and respectively corresponding to multiple postures in the second posture group. On the same vertical reference plane, multiple second cutting planes are formed that are perpendicular to the vertical reference plane and contain the center of mass, respectively corresponding to multiple postures in the second posture group. The second cutting plane is the plane where the center plane of the corresponding second spatial parallel force system intersects with the object to be measured, wherein the center plane of the second spatial parallel force system is perpendicular to the vertical reference plane.

[0013] The intersection line of multiple second cutting planes corresponding to different second spatial parallel force systems is the second centroid line. The second centroid line is perpendicular to the second side of the object under test and parallel to the vertical reference plane.

[0014] Obtain the intersection point of the first centroid line and the second centroid line; the intersection point is the centroid of the object to be tested.

[0015] In conjunction with the first aspect, in one possible implementation, the vertical reference plane is perpendicular to the platform surface of the support platform.

[0016] The solution described in this application, compared with the prior art, utilizes a support platform to hold the object under test and measures the parallel force system under different postures by dividing the support platform into regions. Based on the principle that the central plane of the parallel force system composed of gravity passes through the center of mass, the center of mass line is obtained by measuring the cross-sections of the parallel force system under different postures and the intersection of the cross-sections. The position of the center of mass can be obtained through the intersection of the center of mass lines. The center of mass measurement method of this application does not require suspending the object under test or applying various forces to it. The center of mass can be measured by measuring the pressure of the object under test on the support platform. The measurement method is simple, has almost no requirements on the measurement environment and the shape of the object under test, has a wide range of applications, and the measurement results are accurate and reliable.

[0017] Secondly, embodiments of the present invention also provide a centroid measuring device for implementing the above-described centroid measuring method, comprising:

[0018] Base;

[0019] Multiple measuring units are disposed on the base along a first horizontal direction, each measuring unit forming the bearing area, the measuring unit being used to acquire the gravity exerted on the bearing area by the object under test: and

[0020] The camera unit has its lens facing the support platform and is used to acquire the attitude data of the object under test.

[0021] In conjunction with the second aspect, in one possible implementation, the centroid measuring device further includes a calibration unit, which includes at least one first calibration light source for emitting a calibration beam that overlaps with the first or second cross-section, and the camera unit is capable of capturing an image of the calibration beam emitted by the first calibration light source.

[0022] In conjunction with the second aspect, in one possible implementation, the measuring unit includes a crossbar arranged along a second horizontal direction, a support frame disposed between the crossbar and the base, and a force sensor disposed on the support frame, wherein the second horizontal direction is perpendicular to the first horizontal direction, and the force sensor is used to sense the vertical pressure on the support frame.

[0023] In conjunction with the second aspect, in one possible implementation,

[0024] The support frame includes a vertically arranged vertical rod and a first diagonal rod and a second diagonal rod arranged at an angle. The vertical rod, the horizontal rod, the first diagonal rod and the second diagonal rod are all parallel to the same vertical plane.

[0025] The bottom end of the vertical rod, the lower end of the second inclined rod, and the base are rotatably connected at the first axis; the top end of the vertical rod, one end of the horizontal rod, and the upper end of the first inclined rod are rotatably connected at the second axis; and the center of the first inclined rod and the center of the second inclined rod are rotatably connected at the third axis, wherein the first axis, the second axis, and the third axis are all parallel to the first horizontal direction.

[0026] The upper end of the second inclined rod slides in contact with the lower side of the crossbar, and the lower end of the first inclined rod slides in contact with the upper surface of the base.

[0027] The force sensor is used to sense the vertical pressure on the vertical rod.

[0028] In conjunction with the second aspect, in one possible implementation, the lower end of the first diagonal bar is on the same horizontal plane as the first axis.

[0029] In conjunction with the second aspect, in one possible implementation, the vertical rod is connected to the base via a hinged seat, and the upper surface of the base is a stepped surface corresponding to the first axis and the bottom surface of the hinged seat, respectively.

[0030] The solution described in this application, compared with the prior art, utilizes a support platform formed by multiple measuring units to support the object under test. It measures the parallel force system under different postures by measuring the gravity borne by different measuring units. Based on the principle that the central plane of the parallel force system composed of gravity passes through the center of mass, the center of mass line is obtained by measuring the cross-sections of the parallel force system under different postures and the intersection of these cross-sections. The position of the center of mass is finally obtained through the intersection of these center of mass lines. The center of mass measuring device of this application does not require suspending the object under test or applying various forces to it. The center of mass can be measured by measuring the pressure exerted by the object on the support platform. The measurement method is simple, has almost no requirements on the measurement environment or the shape of the object under test, has a wide range of applications, and provides accurate and reliable measurement results. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the front view structure of a centroid measuring device provided in an embodiment of the present invention;

[0032] Figure 2 for Figure 1 A top-down view, in which the camera unit located at the top is not shown;

[0033] Figure 3 This is a schematic diagram illustrating the principle of using a centroid measurement method according to an embodiment of the present invention to measure the first cross-section of one of the postures in a first posture group;

[0034] Figure 4 This is a schematic diagram illustrating the principle of obtaining the first centroid line through two different postures in a first posture group using a centroid measurement method according to an embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram of the first cutting surface in one state of the centroid measurement method according to an embodiment of the present invention. The shaded part in the test object is the area where the first cutting surface overlaps with the test object.

[0036] Figure 6 This is a schematic diagram illustrating the principle of obtaining the centroid through a first centroid line and a second centroid line using a centroid measurement method according to an embodiment of the present invention.

[0037] Figure 7 This is a top view of the structure of the object to be measured using an embodiment of the present invention for centroid measurement;

[0038] Figure 8This is a schematic diagram illustrating the principle of calculating the first and second cutting planes using an embodiment of the present invention.

[0039] Figure 9 This is a front view schematic diagram of a centroid measuring device according to another embodiment of the present invention, wherein the camera unit, calibration unit, and centroid line calibration unit are not shown;

[0040] Figure 10 This is a schematic diagram of the distributed load acting on the crossbar.

[0041] Figure 11 A force distribution diagram for a single measurement unit;

[0042] Figure 12 This is the force diagram of the horizontal bar;

[0043] Figure 13 This is the force diagram for the second inclined member;

[0044] Figure 14 This is a force diagram at the intersection of the horizontal bar, vertical bar, and second diagonal bar.

[0045] Explanation of reference numerals in the attached figures:

[0046] 1(1a, 1b), the object to be tested; 110, the orientation marker;

[0047] 2. Supporting platform; 210. Supporting area;

[0048] 3. Vertical reference plane;

[0049] 4(4a, 4b), First spatial parallel force system; 410(410a, 410b), First cutting plane;

[0050] 5. First centroidal line;

[0051] 7. Second centroid line;

[0052] 8. Center of mass;

[0053] 9. Base;

[0054] 10. Measuring unit; 1010. Force sensor; 1020. Vertical rod; 1030. Horizontal rod; 1050. First diagonal rod; 1040. Second diagonal rod; 1060. Hinge seat;

[0055] 11. Camera unit;

[0056] 12. Calibration unit; 1210. Calibration light source;

[0057] 14. Limiting components. Detailed Implementation

[0058] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0059] Please refer to the following: Figures 3 to 6 The centroid measurement method provided by this invention will now be described. The centroid measurement method includes the following steps:

[0060] The support platform 2 used to support the object under test 1 is divided into sections along the first horizontal direction (e.g., Figure 2 Multiple load-bearing areas 210 are distributed in the direction indicated by the straight arrows in the first horizontal direction;

[0061] The first attitude group is defined as at least two different attitudes that can be formed when the first side of the object under test 1 contacts the bearing platform 2, and the second attitude group is defined as at least two different attitudes that can be formed when the second side of the object under test 1 contacts the bearing platform 2.

[0062] Based on the gravity borne by each bearing area 210, multiple first spatial parallel force systems 4 are formed along the vertical direction and correspond to multiple postures in the first posture group respectively. Multiple first cutting surfaces 410 corresponding to multiple postures in the first posture group are formed on the same vertical reference surface 3, which are perpendicular to the vertical reference surface and contain the center of mass. The first cutting surface 410 is the surface where the center plane of the corresponding first spatial parallel force system 4 intersects with the object to be measured 1. The vertical reference surface 3 is parallel to the first horizontal direction, and the center plane of the first spatial parallel force system 4 is perpendicular to the vertical reference surface 3.

[0063] The intersection line of multiple first cutting planes 410 corresponding to different first spatial parallel force systems 4 is the first centroid line 5. The first centroid line 5 is perpendicular to the first side of the object to be measured 1 and parallel to the vertical reference plane 3.

[0064] Based on the gravity borne by each bearing area 210, multiple second spatial parallel force systems are formed along the vertical direction and respectively corresponding to multiple postures in the second posture group. For the same vertical reference plane, multiple second cutting planes are formed that are perpendicular to the vertical reference plane and contain the center of mass, respectively corresponding to multiple postures in the second posture group. The second cutting plane is the plane where the center plane of the corresponding second spatial parallel force system intersects with the object to be measured 1, wherein the center plane of the second spatial parallel force system is perpendicular to the vertical reference plane.

[0065] The intersection line of multiple second cutting planes corresponding to different second spatial parallel force systems is the second centroid line 7. The second centroid line 7 is perpendicular to the second side of the object to be measured 1 and parallel to the vertical reference plane 3.

[0066] Obtain the intersection of the first centroid line 5 and the second centroid line 7. This intersection is the centroid 8 of the object to be measured.

[0067] It should be noted that in this embodiment, the first side and the second side of the object under test 1 refer to two different sides of the object under test 1, which can be adjacent sides, opposite sides, etc. The selection of the first side and the second side is determined according to the actual shape of the object under test 1. Based on this, the object under test 1 contacting the bearing platform 2 with its second side is actually flipped in the vertical plane relative to the way it contacts the bearing platform 2 with its first side, such as... Figure 5 and Figure 6 As shown; simultaneously, with the object under test 1 contacting the support platform 2 on the same side, different posture changes actually represent the object under test 1 rotating within the platform 2, as shown. Figure 4 As shown.

[0068] It should also be noted that, for the convenience of illustrating the spatial parallel force system, this application projects the spatial parallel force system, which should actually be perpendicular to the paper, onto a plane parallel to the paper, such as... Figure 3 , Figure 4 and Figure 8 As shown, but should not be interpreted as the spatial parallel force system actually being distributed on a plane parallel to the paper.

[0069] Furthermore, the term "center plane" in this application refers to a plane containing the center of the parallel force system and parallel to the direction of the lines of action of each force. For a parallel force system consisting of the gravity of an object, the center of the parallel force system is the center of gravity, and any vertical plane containing the center of gravity is the center plane.

[0070] The centroid measurement method provided in this embodiment, compared with the prior art, utilizes a support platform 2 to support the object 1 under test, and measures the parallel force system under different postures by dividing the support platform 2 into regions. Based on the principle that the central plane of the parallel force system composed of gravity passes through the centroid, the corresponding cross-sectional plane can be obtained by measuring the central plane of the parallel force system under different postures. The centroid line is obtained through the intersection of the cross-sectional planes, and the position of the centroid can be finally obtained through the intersection of the centroid lines. The centroid measurement method of this application does not require suspending the object 1 under test, nor does it require applying various different forces to the object 1 under test. The centroid can be measured by measuring the pressure of the object 1 under test on the support platform 2. The measurement method is simple, has almost no requirements on the measurement environment and the shape of the object under test, has a wide range of applications, and the measurement results are accurate and reliable.

[0071] Please refer to the following: Figure 8 The principle behind obtaining parameters such as the cutting surface through a parallel force system in this embodiment is as follows:

[0072] Establish a three-dimensional coordinate system (x, y, z), where the x-axis is perpendicular to the vertical reference plane 3, the y-axis is parallel to the platform surface and the vertical reference plane 3, the z-axis is perpendicular to the platform surface and parallel to the vertical reference plane 3, and the positive direction of the z-axis is the direction of gravity.

[0073] The y-coordinate of either the first cutting plane 410 or the second cutting plane is:

[0074]

[0075] p(x,y) is the contact pressure distribution function, Ω is the domain of the contact pressure function, xmax and xmin are the upper and lower limits of the domain's abscissa, ymax and ymin are the upper and lower limits of the domain's ordinate, and y is the ordinate of the infinitesimal area dA.

[0076]

[0077] With the coordinate system fixed, moving the object 1 parallel to the coordinate system will change the position of the y-axis. c However, it will not change the cutting plane; rotating the test object 1 around its center of mass will not change the position of y. c However, it will change the cutting plane; rotating the position of the object 1 around other points will change the y-axis. c This will also change the cutting plane. Using the above calculation formula, the positional information of each cutting plane can be obtained, and ultimately, the intersection line of multiple cutting planes can be calculated.

[0078] In some embodiments, in order to obtain attitude change information of the object under test 1 when its first side contacts the support platform, an orientation mark 110 can be set on the object under test 1. The orientation mark 110 can be formed using the contour of the object under test 1, which is suitable for situations where the contour of the object under test 1 has special characteristics or asymmetry; alternatively, multiple marking points can be formed on the surface of the object under test 1, such as... Figure 7 As shown; or a directional pattern can be formed on the surface of the object to be tested 1. Specific implementation methods are sufficient to meet the requirements of orientation calibration, and will not be listed individually here.

[0079] Based on the accurate acquisition of attitude change information, the first cutting plane 410 or the second cutting plane corresponding to different attitudes can be accurately positioned in the same coordinate system, which facilitates the calculation of the intersection lines of multiple first cutting planes 410 and multiple second cutting planes.

[0080] To reduce the computational difficulty, the following approach is adopted: Figures 3 to 6 As shown, the vertical reference plane 3 is perpendicular to the surface of the support platform 2.

[0081] Based on the same inventive concept, embodiments of this application also provide a centroid measuring device for implementing the above-described centroid measuring method, see reference. Figures 1 to 6 and Figure 8The centroid measuring device includes a base 9, a measuring unit 10, and a camera unit 11. Multiple measuring units 10 are provided, arranged along a first horizontal direction on the base 9. Each measuring unit 10 forms a bearing area 210, and the multiple bearing areas 210 cooperate to form a bearing platform 2. The measuring unit 10 is used to acquire the gravity F exerted on the object under test 1 on the bearing area 210. The lens of the camera unit 11 faces the bearing platform 2, and the camera unit 11 is used to acquire the attitude data of the object under test 1.

[0082] Compared with the prior art, the center of mass measuring device provided in this embodiment utilizes a support platform 2 formed by multiple measuring units 10 to support the object to be measured. It measures the parallel force system under different postures by measuring the gravity borne by different measuring units 10. Based on the principle that the center line of the parallel force system passes through the center of mass, the corresponding cross-section can be obtained by measuring the center line of the parallel force system under different postures. The center of mass line is obtained through the intersection of the cross-sections, and the position of the center of mass can be finally obtained through the intersection of the center of mass lines. The center of mass measuring device of this application does not require suspending the object to be measured 1, nor does it require applying various different forces to the object to be measured 1. The center of mass can be measured by measuring the pressure of the object to be measured 1 on the support platform 2. The measurement method is simple, has almost no requirements on the measurement environment and the shape of the object to be measured 1, has a wide range of applications, and provides accurate and reliable measurement results.

[0083] In practice, the camera unit 11 takes pictures in a direction perpendicular to the vertical reference plane 3. In this embodiment, the camera unit 11 can be connected to a robot arm, sliding structure or other device so that the camera position can be adjusted according to actual usage requirements.

[0084] In some embodiments, see Figure 1 and Figure 2 The centroid measuring device also includes a calibration unit 12, which includes at least one calibration light source 1210. The calibration light source 1210 is used to emit a calibration beam that overlaps with the first cutting surface 410 or the second cutting surface. The camera unit 11 can capture the image of the calibration beam emitted by the calibration light source 1210, and then directly present the position of different cutting surfaces in the image, which is convenient for operators to directly observe the position of the cutting surfaces.

[0085] The specific configuration of the calibration light source 1210 is illustrated here. The calibration unit 12 can be in the form of a lamp array, including multiple calibration light sources 1210 arranged along the first horizontal direction. Different cross-sections can be calibrated by the calibration light sources 1210 at different positions. Alternatively, the calibration unit 12 can have a single calibration light source 1210, with a sliding structure arranged beside the measurement unit 10. The sliding structure can drive the calibration light source 1210 to move along the first horizontal direction, thereby achieving the calibration of different cross-sections.

[0086] The above embodiment forms images of the first cutting surface 410 and the second center line through the first calibration light source 1210, so that the camera unit 11 can capture the first cutting surface 410 and the second center line into their respective posture images of the object to be measured 1. By superimposing the images in the same coordinate system, the corresponding intersection point position can be quickly obtained, improving the intuitiveness and speed of measurement.

[0087] To achieve force measurement and provide support for the object 1 under test, in some embodiments, the measuring unit 10 includes a second horizontal direction (e.g., Figure 1 The crossbar 1030 (shown by the hollow arrow in the diagram), the support frame between the crossbar 1030 and the base 9, and the force sensor 1010 on the support frame are arranged such that the second horizontal direction is perpendicular to the first horizontal direction. The force sensor 1010 is used to sense the vertical pressure on the support frame and obtain the gravity borne by the measuring unit based on the vertical pressure.

[0088] In some embodiments, see Figure 1 , Figure 5 , Figure 6 and Figure 8 The support frame includes a vertically arranged vertical rod 1020 and a first inclined rod 1050 and a second inclined rod 1040 arranged diagonally. The second horizontal direction is perpendicular to the first horizontal direction. The vertical rod 1020, the horizontal rod 1030, the first inclined rod 1050, and the second inclined rod 1040 are all parallel to the same vertical plane. The bottom end of the vertical rod 1020, the lower end of the second inclined rod 1040, and the base 9 are rotatably connected at the first axis. The top end of the vertical rod 1020, one end of the horizontal rod 1030, and the first inclined rod 1050 are connected. The upper end of the first inclined rod 1050 is rotatably connected to the second axis, and the center of the first inclined rod 1050 and the center of the second inclined rod 1040 are rotatably connected to the third axis. The first axis, the second axis, and the third axis are all parallel to the first horizontal direction. The upper end of the second inclined rod 1040 slides in contact with the lower side of the horizontal rod 1030, and the lower end of the first inclined rod 1050 slides in contact with the upper surface of the base 9. The force sensor 1010 is connected to the vertical rod 1020 and is used to sense the vertical pressure on the vertical rod 1020.

[0089] In this embodiment, the measuring unit 10 adopts a rod-shaped component, which has a smaller size in the first horizontal direction, thereby ensuring the density of the load-bearing area 210 division, so that the same parallel force system can contain more parallel forces, which is beneficial to improving the accuracy of centerline calculation.

[0090] In addition, in the measuring unit 10 of this embodiment, the measuring unit 10 does not deform as a whole after the horizontal bar 1030 is compressed, and the pressure F (i.e. the weight it bears) borne by the horizontal bar 1030 is equal to the vertical pressure F' borne by the vertical bar 1020. It can be seen that the measurement of the pressure F' value is the measurement of the weight it bears. This value is measured by the force sensor 1010 connected to the vertical bar 1020.

[0091] In this embodiment, the force sensor 1010 is exemplarily shown as a strain gauge type sensor, which is mounted on the vertical rod 1020. Of course, the force sensor 1010 can also be positioned between the vertical rod 1020 and the base 9 to directly sense the pressure on the vertical rod 1020. It should be understood that the arrangement of the force sensor 1010 is not limited to the example described above; any arrangement that meets the requirement of measuring the vertical pressure on the vertical rod 1020 is acceptable, and will not be listed in detail here.

[0092] To ensure the accuracy of the vertical pressure measurement of the 1020 vertical rod, please refer to... Figure 1 , Figure 5 , Figure 6 and Figure 8 The lower end of the first diagonal bar 1050 is on the same horizontal plane as the first axis.

[0093] Based on the above embodiment, the vertical rod is connected to the base 9 via a hinge seat 1060. The upper surface of the base 9 is a stepped surface corresponding to the first axis and the bottom surface of the hinge seat 1060, respectively. In this embodiment, the hinge seat 1060 facilitates the installation of the vertical rod 1020, and the stepped surface of the base 9 meets the requirements for measurement accuracy while simplifying the structure of the base 9 and improving ease of use.

[0094] Of course, the specific arrangement of the measuring unit 10 is not limited to the methods listed above. Here, one of the other methods is illustrated as an example: The measuring unit 10 includes a vertically arranged vertical rod and a horizontally arranged support rod. The middle part of the support rod is fixedly connected to the top of the vertical rod. The force sensor between the bottom of the vertical rod and the base 9 is a pressure sensor, which directly senses the gravity it bears. Other embodiments will not be listed here one by one, as long as they meet the measurement requirements.

[0095] The measurement unit 10 in the above embodiment can be simplified as follows: Figure 10 The structure shown is as follows, where AD represents the horizontal bar 1030, AB represents the vertical bar 1020, AE represents the first diagonal bar 1050, and BD represents the second diagonal bar 1040. Based on this structure, the aforementioned formulas (1) and (2) are explained, that is, the vertical pressure q(y) of the vertical bar 1020 measured at point y is equal to the sum of the contact pressure p(x, y) along the x direction at this point, as follows:

[0096] like Figure 10 As shown, rod AD is subjected to a distributed load p(x). Prove that the pressure on rod AB is...

[0097] Taking a single measuring unit 10 as the research object, its force diagram is shown below. Figure 11 Assume that the lengths of AD and BE are both l, and the angle between BE and AE is θ. A small force p(x)dx is applied at a distance x from point A. Bx F By and F Ey These are constraint reactions; the equilibrium equations for the force system are:

[0098]

[0099] Solving for:

[0100]

[0101] The force diagram of rod AD is shown below. Figure 12 F A2x and F A2y The two components of the support constraint reaction force; F D2y It is a supporting force. The equilibrium equations of the force system are:

[0102]

[0103] Solving for:

[0104]

[0105] The force diagram of rod AE is shown below. Figure 13 F A3x and F A3y F represents the two components of the force applied by pin A. Cx and F Cy The two components of the force exerted by BD. The moment equilibrium equations are written with respect to point C:

[0106]

[0107] The force diagram of pin A is shown below. Figure 14 Assume that the pressure on rod AB under the action of a small force p(x)dx is dF1. The equilibrium equations of the force system are:

[0108]

[0109] Solving the combined equations (4), (6), (7), and (8) yields:

[0110] dF1=p(x)dx. (9)

[0111] Therefore, under the action of p(x), the pressure q on rod AB is:

[0112]

[0113] In some embodiments, to achieve positioning of the object 1 in different postures, the following methods can be used: Figure 9 The structure shown includes limiting members 14 (e.g., limiting plates) arranged circumferentially on the supporting platform 2. Each limiting member 14 has a vertically arranged limiting surface and can move horizontally under the drive of the driving structure, thereby achieving limiting by contacting the object under test 1 on one or more sides. It should be noted that, since the limiting surface is a vertical and smooth plane, the limiting member 14 itself does not generate supporting force, pressure, or significant friction on the object under test 1, and will not affect the pressure sensing of the measuring unit 10.

[0114] Based on the above embodiments, the driving structure connected to the limiting member 14 can not only adjust the position of the limiting member 14 in the horizontal direction, but also adjust the height of the limiting member 14 in the vertical direction. In this way, the position of the limiting member 14 can be adjusted according to the different shapes and different placement positions of the object to be tested 1, and unnecessary interference with the object to be tested 1 can also be avoided.

[0115] For example, from the perspective of 9, limiters 14 are set on the left and right sides of the measuring unit 10. Since the outer periphery of the object to be measured 1 is relatively smooth, it is difficult to form a stable support on its own. By limiting the object to be measured 1 on the left and right sides through the limiters 1, the object to be measured 1 can maintain the preset posture and improve the ease of use.

[0116] The specific steps for implementing the centroid measurement method using the centroid measurement device of this application are as follows:

[0117] 1) Select a plane perpendicular to the bearing platform 2 as the vertical reference plane 3. The vertical reference plane 3 should preferably be located on one side of the object to be measured 1 and should not interfere with the object to be measured 1; the camera unit 11 should take pictures downwards (e.g., Figure 1 As shown), at the same time, three point-shaped directional markers 110 distributed in a triangle are set on the object to be tested 1;

[0118] 2) Place the object to be tested 1a against the first side of the support platform 2. At this time, its posture is posture one in the first posture group (e.g., Figure 3 and Figure 5 As shown), after the object to be measured 1 is placed stably, the gravity F borne by each measuring unit 10 in the vertical reference plane 3 is obtained. These gravity forces form the first spatial parallel force system 4a, which is a planar parallel force system.

[0119] 3) Calculate the first cutting surface 410a of the first spatial parallel force system 4a, and generate a red calibration beam (e.g., a red laser beam) through the first calibration light source 1210. This calibration beam represents the first cutting surface 410a. The camera unit 11 located above simultaneously acquires the superimposed image of the object under test and the calibration beam (e.g., ...). Figure 3 (as shown);

[0120] 4) Rotate the object under test 1a parallel to the surface of the support platform 2, so that it rotates to attitude two, which belongs to the first attitude group. Figure 4 For the test object 1b, repeat steps 2) to 3) above, so that the camera unit 11 located above can acquire a superimposed image of the test object and the calibration beam at this time (e.g., Figure 4 (as shown);

[0121] 5) Calculate the intersection line of the first cutting plane 410a and the first cutting plane 410b to obtain the first centroid line 5;

[0122] 6) Rotate the object to be tested 1 in the vertical plane so that its second side is placed against the supporting platform 2, as shown. Figure 6 As shown, the current attitude is attitude three in the second attitude group. Then, repeat steps 2) to 3) above to obtain the superimposed image of the test object and the calibration beam corresponding to attitude three.

[0123] 7) Rotate the test object 1 parallel to the surface of the support platform 2 to rotate it to posture four, which belongs to the second posture group. Repeat steps 2) to 3) above to obtain the superimposed image of the test object and the calibration beam corresponding to posture three.

[0124] 8) Calculate the intersection line of the two second cutting planes corresponding to the two attitudes to obtain the second centroid line 7;

[0125] 9) Calculate the intersection point of the first centroid line 5 and the second centroid line 7 in the same three-dimensional coordinate system, thus obtaining the position data of the centroid 8;

[0126] 10) Generate three-dimensional images of the test object 1 and the centroid 8 through a computer or other terminal.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of centroid measurement, characterized by, The method comprises the following steps: a load platform for supporting the object to be measured is divided into a plurality of load areas distributed along a first horizontal direction; at least two different postures that can be formed when a first side of the object to be measured contacts the load platform are defined as a first posture group, and at least two different postures that can be formed when a second side of the object to be measured contacts the load platform are defined as a second posture group; a plurality of first spatial parallel force systems along a vertical direction and respectively corresponding to a plurality of postures in the first posture group are formed according to the gravity borne by each of the load areas, and for a same vertical reference surface, a plurality of first cross sections perpendicular to the vertical reference surface and containing the center of mass are formed respectively corresponding to a plurality of postures in the first posture group, the first cross sections being the surfaces intersected by the center surface corresponding to the first spatial parallel force system and the object to be measured, wherein the vertical reference surface is parallel to the first horizontal direction, and the center surface of the first spatial parallel force system is perpendicular to the vertical reference surface; the intersection of a plurality of first cross sections corresponding to different first spatial parallel force systems is a first center-of-mass line, the first center-of-mass line is perpendicular to the first side of the object to be measured and parallel to the vertical reference surface; a plurality of second spatial parallel force systems along a vertical direction and respectively corresponding to a plurality of postures in the second posture group are formed according to the gravity borne by each of the load areas, and for a same vertical reference surface, a plurality of second cross sections perpendicular to the vertical reference surface and containing the center of mass are formed respectively corresponding to a plurality of postures in the second posture group, the second cross sections being the surfaces intersected by the center surface corresponding to the second spatial parallel force system and the object to be measured, wherein the center surface of the second spatial parallel force system is perpendicular to the vertical reference surface; the intersection of a plurality of second cross sections corresponding to different second spatial parallel force systems is a second center-of-mass line, the second center-of-mass line is perpendicular to the second side of the object to be measured and parallel to the vertical reference surface; the intersection of the first center-of-mass line and the second center-of-mass line is the center of mass of the object to be measured.

2. The method of center of mass measurement of claim 1, wherein, The vertical reference surface is perpendicular to the table surface of the load platform.

3. A center-of-mass measuring apparatus for implementing the center-of-mass measuring method according to claim 1 or 2, characterized by, The center-of-mass measuring device comprises: a base; a plurality of measurement units arranged on the base along a first horizontal direction, each of the measurement units forming a load area, and the measurement units being used to obtain the gravity borne by the object to be measured on the load area; and a camera unit with a lens facing the load platform, the camera unit being used to obtain posture data of the object to be measured.

4. The center of mass measurement device of claim 3, wherein, The center-of-mass measuring device further comprises a calibration unit, the calibration unit comprising at least one first calibration light source, the first calibration light source being used to emit a calibration light beam overlapping with the first cross section or the second cross section, and the camera unit being able to capture an image of the calibration light beam emitted by the first calibration light source.

5. The center of mass measurement device of claim 3, wherein, The measurement unit comprises a crossbar arranged along a second horizontal direction, a support frame arranged between the crossbar and the base, and a force sensor arranged on the support frame, the second horizontal direction being perpendicular to the first horizontal direction, and the force sensor being used to sense the vertical pressure borne by the support frame.

6. The center-of-mass measuring device according to claim 5, wherein The support frame comprises a vertical pole arranged vertically, and a first inclined pole and a second inclined pole arranged obliquely, the vertical pole, the horizontal pole, the first inclined pole and the second inclined pole are parallel to the same vertical plane; a bottom end of the vertical pole, a lower end of the second inclined pole and the base are rotationally connected at a first axis, a top end of the vertical pole, one end of the horizontal pole and an upper end of the first inclined pole are rotationally connected at a second axis, and a center of the first inclined pole and a center of the second inclined pole are rotationally connected at a third axis, wherein the first axis, the second axis and the third axis are parallel to the first horizontal direction; an upper end of the second inclined pole is in sliding contact with a lower side surface of the horizontal pole, and a lower end of the first inclined pole is in sliding contact with an upper surface of the base; the force sensor is configured to sense a vertical pressure received by the vertical pole.

7. The center of mass measurement device of claim 6, wherein, the lower end of the first inclined pole is in the same horizontal plane as the first axis.

8. The center of mass measurement device of claim 7, wherein, the vertical pole is connected to the base through a hinged seat, and an upper surface of the base is a stepped surface corresponding to the first axis and a bottom surface of the hinged seat, respectively.

Images