Measurement Method and Measuring Device for Collision Contact Point of Pedestrian Protection Headform Impactor

Abstract

The present application relates to the technical field of vehicle collision safety, and particularly relates to a method and a device for measuring the collision contact point of a pedestrian protection headform impactor. The measurement method includes: placing the headform impactor along its own central axis opposite to the impact target point of the cover plate so that the headform impactor contacts the cover plate; fitting the spherical shell face mask to the arc spherical surface of the headform impactor and rotating it to abut the wedge part between the headform impactor and the cover plate; respectively drawing a first arc segment, a second arc segment and a third arc segment along the position where the arc spherical surface of the headform impactor intersects with the end face of the spherical shell face mask; moving the headform impactor in the reverse direction of the impact direction to extend the first arc segment, the second arc segment and the third arc segment, respectively obtaining a fourth arc segment, a fifth arc segment and a sixth arc segment, and the intersection point of the three is the collision contact point of the headform impactor. Thus, the collision contact point of the headform impactor can be determined, the operation is convenient, the repeatability is good, and it is beneficial to improve the test efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle collision safety, and particularly relates to a method and a device for measuring the collision contact point of a pedestrian protection headform impactor. Background Art

[0002] With the rapid increase in the number of vehicles, the number of collisions between people and vehicles has gradually increased. Various pedestrian protection evaluation rules such as E-NCAP, C-NCAP, C-IASI, etc. require using a headform impactor to collide with a vehicle to simulate the injuries suffered by a pedestrian's head in a traffic accident. Usually, the evaluation rules require the center of the headform impactor to aim at the target point. However, since the headform impactor is approximately half a sphere and has a relatively large impact angle, the target point of the headform impactor is not the first contact point when it collides with the vehicle. According to the requirements of the evaluation rules, the position accuracy of the headform impactor is ±10 mm. It is necessary to apply paint to either the headform impactor or the vehicle fascia, and after the collision test, observe the position of the paint mark on the other and the deviation therefrom. This position deviation is the impact position error.

[0003] Currently, there are two methods for determining the first contact point: One is to apply paint in advance at the position where the headform is likely to first contact the vehicle, move the headform in the impact direction, and the spherical surface of the headform impactor gradually approaches and contacts the vehicle. The paint is applied to the vehicle fascia to produce the first contact point. This method is not only easily affected by the accuracy of the pre-judged position, but also the area of the paint contact is relatively large, making it difficult to determine the center contact point; The second method is to observe and remember the position of the first contact point on the vehicle fascia when the spherical surface of the headform impactor contacts the vehicle fascia to produce the first contact point. After moving the headform impactor away in the reverse direction of the impact direction, stick a circular marking point on the vehicle fascia, and then place another circular marking point (with the adhesive surface facing up) on the reverse side of this circular marking point. Repeat the process of forming the first contact point and paste the second circular marking point on the headform impactor. This method has problems such as difficult observation and large errors in actual operation, and poor repeatability, which affects the test efficiency. Summary of the Invention

[0004] The purpose of the present application is to provide a method and a device for measuring the collision contact point of a pedestrian protection headform impactor, which can accurately determine the collision contact point of the headform impactor, are convenient to operate, have good repeatability, and are conducive to improving the test efficiency.

[0005] To achieve the above object, in a first aspect, the present application provides a method for measuring the collision contact point of a pedestrian protection headform impactor, including: providing a headform impactor, a cover plate, and a spherical shell mask. The headform impactor has an arc-shaped spherical surface, and an impact target point is provided on the cover plate. The spherical shell mask is a hemispherical thin shell structure that can fit and match with the arc-shaped spherical surface of the headform impactor. A wedge portion is provided on the circumferential side of the end surface of the spherical shell mask. The wedge portion is a plane formed by a depression on the circumferential side of the end surface and perpendicular to the diameter direction of the end surface; place the headform impactor along the extension direction of its own center line to align with the impact target point of the cover plate so that the headform impactor contacts the cover plate; fit the spherical shell mask to the arc-shaped spherical surface of the headform impactor and rotate it to abut the wedge portion against the collision contact point between the headform impactor and the cover plate; draw a first arc segment along the intersection position of the arc-shaped spherical surface of the headform impactor and the end surface of the spherical shell mask; with the collision contact point as the center of the sphere, rotate the spherical shell mask at any angle, and draw a second arc segment along the intersection position of the arc-shaped spherical surface of the headform impactor and the end surface of the spherical shell mask; with the collision contact point as the center of the sphere, continue to rotate the spherical shell mask at any angle, and draw a third arc segment along the intersection position of the arc-shaped spherical surface of the headform impactor and the end surface of the spherical shell mask; move the headform impactor in the reverse direction of the impact direction to separate the headform impactor from the cover plate; coincide the end surface of the spherical shell mask with the first arc segment and extend the first arc segment to obtain a fourth arc segment; coincide the end surface of the spherical shell mask with the second arc segment and extend the second arc segment to obtain a fifth arc segment; coincide the end surface of the spherical shell mask with the third arc segment and extend the third arc segment to obtain a sixth arc segment. The intersection point of the fourth arc segment, the fifth arc segment, and the sixth arc segment is the collision contact point of the headform impactor.

[0006] Further, fitting the spherical shell mask to the arc-shaped spherical surface of the headform impactor and rotating it includes: if the friction between the spherical shell mask and the arc-shaped spherical surface of the headform impactor is large, move the spherical shell mask radially outward to form a certain gap between it and the arc-shaped spherical surface of the headform impactor; rotate the spherical shell mask to abut the wedge portion against the collision contact point between the headform impactor and the cover plate.

[0007] Further, a positioning hole opposite to the wedge portion is also provided on the circumferential side of the end surface of the spherical shell mask. After determining the collision contact point, the measurement method further includes: rotating the spherical shell mask to make the center of the positioning hole coincide with the collision contact point of the headform impactor; attaching a circular mark through the positioning hole to the collision contact point.

[0008] Further, if the fourth arc segment, the fifth arc segment, and the sixth arc segment intersect to form three intersection points, and the distance between any two intersection points is greater than the evaluation threshold, it is necessary to re-determine the collision contact point.

[0009] Further, the spherical shell mask is also provided with an operation handle, and the spherical shell mask is rotated through the operation handle.

[0010] In a second aspect, an embodiment of the present application provides a measuring device for the collision contact point of a pedestrian protection headform impactor, including: a headform impactor having an arc-shaped spherical surface; a cover plate provided with an impact target point, the center line of the headform impactor being aligned with the impact target point so that the headform impactor contacts the cover plate; and a spherical shell face mask, which is a hemispherical thin shell structure, and a wedge-shaped portion is provided on the circumferential side of the end face of the spherical shell face mask. The wedge-shaped portion is a plane formed by a depression on the circumferential side of the end face and perpendicular to the diameter direction of the end face. The spherical shell face mask can be fitted and relatively rotated with the arc-shaped spherical surface of the headform impactor to abut the wedge-shaped portion between the headform impactor and the cover plate.

[0011] Further, the plane of the wedge-shaped portion is tangentially provided with the inner wall of the adjacent spherical shell face mask.

[0012] Further, the central angle corresponding to the plane of the wedge-shaped portion is θ, the radius of the spherical shell face mask is R, and the maximum length dimension L of the plane of the wedge-shaped portion along its own radial direction is L = R×sinθ.

[0013] Further, the measuring device further includes a circular marking sticker. A positioning hole opposite to the wedge-shaped portion is also provided on the circumferential side of the end face of the spherical shell face mask. The circular marking sticker is attached to the determined collision contact point of the headform impactor through the positioning hole.

[0014] Further, an operation handle is also provided on the spherical shell face mask to rotate the spherical shell face mask through the operation handle.

[0015] The measuring method and measuring device for the collision contact point of the pedestrian protection headform impactor provided by the embodiments of the present application have the following beneficial effects: By fitting the spherical shell face mask with the arc-shaped spherical surface of the headform impactor and abutting the wedge-shaped portion of the spherical shell face mask against the collision contact point between the headform impactor and the cover plate, and then taking the collision contact point as the center of the sphere and rotating the spherical shell face mask at any angle, the first arc segment, the second arc segment and the third arc segment are respectively drawn along the intersection position of the arc-shaped spherical surface of the headform impactor and the end face of the spherical shell face mask; then the headform impactor is moved in the reverse direction of the impact direction to separate the headform impactor from the cover plate, and the fourth arc segment, the fifth arc segment and the sixth arc segment are drawn on the extension lines of the first arc segment, the second arc segment and the third arc segment respectively drawn on the headform impactor. The intersection point of the three is the collision contact point of the headform impactor. Since the collision contact point between the headform impactor and the cover plate must be on each arc segment, theoretically the intersection point of any two arc segments is the collision contact point to be found, and the intersection point generated by the intersection of the third arc segment and the first two arc segments is used to verify the operation accuracy, which has a self-checking function. Thus, the collision contact point of the headform impactor can be accurately determined, the test accuracy is improved, and the operation is convenient and the repeatability is good, improving the test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1Flow chart showing the method for measuring the collision contact point of a pedestrian protection headform impactor provided by an embodiment of the present application;

[0017] Figure 2 Schematic diagram showing the effect when the headform impactor collides with the cover plate;

[0018] Figure 3 Schematic diagram showing the measuring device for the collision contact point of a pedestrian protection headform impactor provided by an embodiment of the present application;

[0019] Figure 4 Show Figure 3 Schematic diagrams of the spherical shell mask in along various angles;

[0020] Figure 5 Schematic diagram showing the position of the collision contact point on the headform impactor.

[0021] Wherein, 1. Headform impactor; 10. Central axis; 11. Arc spherical surface; S1. First arc segment; S2. Second arc segment; S3. Third arc segment; S4. Fourth arc segment; S5. Fifth arc segment; S6. Sixth arc segment; C. Collision contact point;

[0022] 2. Cover plate; O. Impact target point;

[0023] 3. Spherical shell mask; 31. Wedge part; 32. Positioning hole; 33. Operation handle; 34. End face. Detailed implementation manners

[0024] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for explaining the present invention, rather than for limiting the protection scope of the present invention.

[0025] It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, numbers, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0026] As Figure 1 shown, an embodiment of the present application provides a method for measuring the collision contact point of a pedestrian protection headform impactor, including the following steps S1 to S10. The following will be described in conjunction with the attached Figures 2 to 5Describe in detail the specific steps of the method for measuring the collision contact point of the pedestrian protection headform impactor.

[0027] Step S1: Provide a headform impactor 1, a cover plate 2, and a spherical shell mask 3. The headform impactor 1 has an arc-shaped spherical surface 11. An impact target point O is set on the cover plate 2. The spherical shell mask 3 is a hemispherical thin shell structure that can fit and match with the arc-shaped spherical surface 11 of the headform impactor 1. A wedge portion 31 is provided on the periphery of the end face 34 of the spherical shell mask 3. The wedge portion 31 is a plane formed by recessing from the periphery of the end face 34 and perpendicular to the diameter direction of the end face 34.

[0028] As Figures 2 to 4 shown, the headform impactor 1 collides with the cover plate 2 to simulate the injury suffered by a pedestrian's head in a traffic accident. Among them, the headform impactor 1 is designed in the shape of a large half sphere according to the requirements of relevant pedestrian protection evaluation rules and has a large impact angle. The spherical shell mask 3 is used to assist in determining the position of the collision contact point C on the headform impactor 1.

[0029] Step S2: Place the headform impactor 1 along the extension direction of its own central axis 10 and align it with the impact target point O of the cover plate 2 so that the headform impactor 1 contacts the cover plate 2.

[0030] When conducting a pedestrian protection headform impact test according to evaluation rules such as C-NCAP, the central axis 10 of the headform impactor 1 is the impact direction. When the headform impactor 1 is placed along the extension direction of its own central axis 10 and aligned with the impact target point O of the cover plate 2, the lower left hemisphere part of the headform impactor 1 will first contact the point on the cover plate 2, and this point is the collision contact point C of the cover plate 2. The corresponding collision contact point C of the headform impactor 1 still needs to be determined.

[0031] Step S3: Fit the spherical shell mask 3 to the arc-shaped spherical surface 11 of the headform impactor 1 and rotate it to abut the wedge portion 31 against the collision contact point C between the headform impactor 1 and the cover plate 2.

[0032] As Figure 3 shown, the spherical shell mask 3 is a hemispherical thin shell structure. Its wedge portion 31 is a plane formed by recessing from the periphery of the end face 34 and perpendicular to the diameter direction of the end face 34. One side of the inner wall of this plane is a thinner wedge-shaped structure that can be inserted between the headform impactor 1 and the cover plate 2 until it abuts against the collision contact point C between the two.

[0033] Step S4: Draw a first arc segment S1 on the arc-shaped spherical surface 11 of the headform impactor 1 along the intersection position between it and the end face 34 of the spherical shell mask 3.

[0034] Step S5: With the collision contact point C as the center of the sphere, rotate the spherical shell face mask 3 by any angle, and draw a second arc segment S2 on the arc-shaped spherical surface 11 of the head form impactor 1 along the intersection position of the arc-shaped spherical surface 11 and the end face 34 of the spherical shell face mask 3.

[0035] Step S6: Continue to rotate the spherical shell face mask 3 by any angle, and draw a third arc segment S3 on the arc-shaped spherical surface 11 of the head form impactor 1 along the intersection position of the arc-shaped spherical surface 11 and the end face 34 of the spherical shell face mask 3.

[0036] Step S7: Move the head form impactor 1 in the reverse direction of the impact direction, so that the head form impactor 1 is separated from the cover plate 2.

[0037] Step S8: Coincide the end face 34 of the spherical shell face mask 3 with the first arc segment S1, and extend the first arc segment S1 to obtain a fourth arc segment S4.

[0038] Step S9: Coincide the end face 34 of the spherical shell face mask 3 with the second arc segment S2, and extend the second arc segment S2 to obtain a fifth arc segment S5.

[0039] Step S10: Coincide the end face 34 of the spherical shell face mask 3 with the third arc segment S3, and extend the third arc segment S3 to obtain a sixth arc segment S6. The intersection points of the fourth arc segment S4, the fifth arc segment S5 and the sixth arc segment S6 are the collision contact point C of the head form impactor 1.

[0040] Figure 5 The positions of the first arc segment S1, the second arc segment S2, the third arc segment S3, the fourth arc segment S4, the fifth arc segment S5 and the sixth arc segment S6 on the head form impactor 1 marked with a marker pen are shown. Since the collision contact point C between the head form impactor 1 and the cover plate 2 must be on each arc segment, theoretically the intersection point of any two arc segments is the collision contact point C to be found. The intersection point generated by the third arc segment intersecting with the first two arc segments is used to verify the operation accuracy: If the third arc segment intersects with the first two arc segments at the same point, it means that the positioning is accurate and meets the position accuracy requirements specified in the evaluation rules. As Figure 5 shown, the fourth arc segment S4, the fifth arc segment S5 and the sixth arc segment S6 intersect at the same intersection point, which is the collision contact point C of the head form impactor 1.

[0041] According to the measurement method of the collision contact point of the pedestrian protection headform impactor provided by the embodiments of the present application, the spherical shell mask 3 is fitted to the arc-shaped spherical surface 11 of the headform impactor 1, and the wedge-shaped part 31 of the spherical shell mask 3 is abutted against the collision contact point C between the headform impactor 1 and the cover plate 2. Then, with the collision contact point C as the center of the sphere, the spherical shell mask 3 is rotated at any angle, and the first arc segment S1, the second arc segment S2, and the third arc segment S3 are respectively drawn along the intersection position of the arc-shaped spherical surface 11 of the headform impactor 1 and the end face 34 of the spherical shell mask 3. Then, the headform impactor 1 is moved in the reverse direction of the impact direction to separate the headform impactor 1 from the cover plate 2, and the fourth arc segment S4, the fifth arc segment S5, and the sixth arc segment S6, which are the extension lines of the first arc segment S1, the second arc segment S2, and the third arc segment S3 respectively, are drawn on the headform impactor 1. The intersection point of the three is the collision contact point C of the headform impactor 1. Since the collision contact point C between the headform impactor 1 and the cover plate 2 must be on each arc segment, theoretically, the intersection point of any two arc segments is the collision contact point to be found, and the intersection point generated by the intersection of the third arc segment and the first two arc segments is used to verify the operation accuracy, which has a self-checking function. Thus, the collision contact point C of the headform impactor 1 can be accurately determined, the test accuracy is improved, the operation is convenient, the repeatability is good, and the test efficiency is improved.

[0042] Further, in step S3, fitting the spherical shell mask 3 to the arc-shaped spherical surface 11 of the headform impactor 1 and rotating it includes:

[0043] Step S31: If the friction force between the spherical shell mask 3 and the arc-shaped spherical surface 11 of the headform impactor 1 is large, the spherical shell mask 3 is radially moved outwards to form a certain gap between it and the arc-shaped spherical surface 11 of the headform impactor 1;

[0044] Step S32: Rotate the spherical shell mask 3 to abut the wedge-shaped part 31 against the collision contact point C between the headform impactor 1 and the cover plate 2.

[0045] Further, a positioning hole 32 opposite to the wedge-shaped part 31 is also provided on the periphery of the end face 34 of the spherical shell mask 3. After determining the collision contact point C, the measurement method further includes:

[0046] Step S11: Rotate the spherical shell mask 3 to make the center of the positioning hole 32 coincide with the collision contact point C of the headform impactor 1;

[0047] Step S12: Stick the circular mark through the positioning hole 32 onto the collision contact point C.

[0048] Such as Figure 4As shown, the shape of the positioning hole 32 is semi-circular. The circular label is attached to the collision contact point C through the positioning hole 32. The aperture diameter of the positioning hole 32 is the same as the diameter of the circular label. After determining the position of the collision contact point C, rotate the center of the positioning hole 3 to the collision contact point C, and paste the circular label from the edge of the positioning hole 32. The center point of the circular label is the collision contact point C. The shape of the positioning hole 32 can also be circular, which will not be elaborated here.

[0049] Furthermore, the measurement method further includes:

[0050] Step S13: If the fourth arc segment S4, the fifth arc segment S5, and the sixth arc segment S6 intersect to form three intersection points, and the distance between any two intersection points is greater than the evaluation threshold, then the position accuracy of the collision contact point C does not meet the requirements, and it is necessary to re-determine the collision contact point C.

[0051] According to evaluation rules such as C-NCAP, the position accuracy requirement for the collision contact point C of the head form impactor 1 is ±10 mm, that is, the evaluation threshold is ±10 mm. As mentioned above, the intersection points generated by the third arc segment and the first two arc segments are used to verify the operation accuracy: If the fourth arc segment S4, the fifth arc segment S5, and the sixth arc segment S6 intersect to form three intersection points, and the distance between any two intersection points is greater than the evaluation threshold, then the position accuracy of the collision contact point C does not meet the requirements, and it is necessary to re-determine the collision contact point C until the position accuracy of the collision contact point C meets the requirements.

[0052] Furthermore, the spherical shell mask 3 is also provided with an operation handle 33 to rotate the spherical shell mask 3 through the operation handle 33. As Figures 3 to 5 shown, the spherical shell mask 3 is also provided with an operation handle 33. The shape of the operation handle 33 can be approximately spherical, which is convenient for manual operation to move or rotate the spherical shell mask 3.

[0053] As Figure 3 shown, the embodiment of the present application also provides a measuring device for the collision contact point of a pedestrian protection head form impactor, including: a head form impactor 1, a cover plate 2, and a spherical shell mask 3.

[0054] The head form impactor 1 has an arc-shaped spherical surface 11; the cover plate 2 is provided with an impact target point O, and the central axis 10 of the head form impactor 1 is aligned with the impact target point O so that the head form impactor 1 contacts the cover plate 2.

[0055] The spherical shell face mask 3 is a hemispherical thin shell structure, and the wall thickness can be about 0.5 mm. A wedge portion 31 is provided on the circumferential side of the end face 34 of the spherical shell face mask 3. The wedge portion 31 is a plane formed by the depression of the circumferential side of the end face 34 and perpendicular to the diameter direction of the end face 34. The spherical shell face mask 3 can be fitted and mated with the arc spherical surface 11 of the head form impactor 1 and rotate relative to it, so as to abut the wedge portion 31 against the collision contact point C between the head form impactor 1 and the cover plate 2.

[0056] Further, the plane of the wedge portion 31 is tangent to the inner wall of the adjacent spherical shell face mask 3. One side of the inner wall of the wedge portion 31 is a relatively thin wedge structure, which can be inserted between the head form impactor 1 and the cover plate 2 until it abuts against the collision contact point C between the two.

[0057] Further, as Figure 4 shown, the central angle corresponding to the plane of the wedge portion 31 is θ, the radius of the spherical shell face mask 3 is R, and the maximum length dimension L of the plane of the wedge portion 31 along its own radial direction is L = R×sinθ.

[0058] In the embodiment of the present application, the diameter of the head form impactor 1 is 165 mm, and the inner diameter of the spherical shell face mask 3 is the same as the diameter of the head form impactor 1, so the radius of the spherical shell face mask 3 is R = 82.5 mm. The plane shape of the wedge portion 31 is approximately a large semi-circle. After the central angle θ corresponding to the plane of the wedge portion 31 is determined, the maximum length dimension L of the plane of the wedge portion 31 along its own radial direction can be obtained.

[0059] Further, the measuring device further includes a circular marking sticker (not shown in the figure). A positioning hole 32 opposite to the wedge portion 31 is also provided on the circumferential side of the end face 34 of the spherical shell face mask 3. The circular marking sticker is attached to the determined collision contact point C of the head form impactor 1 through the positioning hole 32.

[0060] The shape of the positioning hole 32 is semi-circular, and the circular marking sticker is attached to the collision contact point C through the positioning hole 32. The aperture of the positioning hole 32 is consistent with the diameter of the circular marking sticker. After the position of the collision contact point C is determined, rotate the center of the position of the positioning hole 3 to the collision contact point C, and paste the circular marking sticker from the edge of the positioning hole 32. The center point of the circular marking sticker is the collision contact point C. The shape of the positioning hole 32 can also be circular, which will not be elaborated here.

[0061] Further, the spherical shell face mask 3 is also provided with an operation handle 33, and the spherical shell face mask 3 is rotated through the operation handle 33. The shape of the operation handle 33 can be approximately spherical, which is convenient for manual operation to move or rotate the spherical shell face mask 3.

[0062] It should be noted that phrases such as "an embodiment", "embodiments", "exemplary embodiments", "some embodiments", etc. mentioned in the specification indicate that the described embodiments may include specific features, structures or characteristics, but not necessarily every embodiment includes such specific features, structures or characteristics. In addition, such phrases do not necessarily refer to the same embodiment. Moreover, when combining specific features, structures or characteristics with an embodiment, implementing such features, structures or characteristics in other embodiments, whether explicitly or implicitly described, is within the knowledge scope of those skilled in the art.

[0063] It should be noted that, in this article, relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0064] Finally, it should be stated that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for measuring the collision contact point of a pedestrian protection headform impactor, characterized in that, Including: Provided are a head form impactor, a cover plate and a spherical shell face mask. The head form impactor has an arc spherical surface. An impact target point is provided on the cover plate. The spherical shell face mask is a hemispherical thin shell structure, which can be fitted and matched with the arc spherical surface of the head form impactor. A wedge part is provided on the circumferential side of the end face of the spherical shell face mask. The wedge part is a plane formed by recessing from the circumferential side of the end face and perpendicular to the diameter direction of the end face; Place the head form impactor along the extension direction of its own center line to align with the impact target point of the cover plate, so that the head form impactor contacts the cover plate; Fit the spherical shell face mask to the arc spherical surface of the head form impactor and rotate it to abut the wedge part against the collision contact point between the head form impactor and the cover plate; Draw a first arc segment along the intersection position of the arc spherical surface of the head form impactor and the end face of the spherical shell face mask; Taking the collision contact point as the center of the sphere, rotate the spherical shell face mask by any angle, and draw a second arc segment along the intersection position of the arc spherical surface of the head form impactor and the end face of the spherical shell face mask; Taking the collision contact point as the center of the sphere, continue to rotate the spherical shell face mask by any angle, and draw a third arc segment along the intersection position of the arc spherical surface of the head form impactor and the end face of the spherical shell face mask; Move the head form impactor in the reverse direction of the impact direction to separate the head form impactor from the cover plate; Coincide the end face of the spherical shell face mask with the first arc segment and extend the first arc segment to obtain a fourth arc segment; Coincide the end face of the spherical shell face mask with the second arc segment and extend the second arc segment to obtain a fifth arc segment; Coincide the end face of the spherical shell face mask with the third arc segment and extend the third arc segment to obtain a sixth arc segment. The intersection point of the fourth arc segment, the fifth arc segment and the sixth arc segment is the collision contact point of the head form impactor.

2. The measuring method according to claim 1, characterized in that, The fitting the spherical shell face mask to the arc spherical surface of the head form impactor and rotating it includes: If the friction force between the spherical shell face mask and the arc spherical surface of the head form impactor is large, move the spherical shell face mask radially outwards to form a certain gap between it and the arc spherical surface of the head form impactor; Rotate the spherical shell face mask to abut the wedge part against the collision contact point between the head form impactor and the cover plate.

3. The measuring method according to claim 2, characterized in that, A positioning hole opposite to the wedge part is further provided on the circumferential side of the end face of the spherical shell face mask. After determining the collision contact point, the measuring method further includes: Rotate the spherical shell face mask to make the center of the positioning hole coincide with the collision contact point of the head form impactor; Attach a circular mark through the positioning hole to the collision contact point.

4. The measurement method according to claim 1, characterized in that, If the fourth arc segment, the fifth arc segment and the sixth arc segment intersect to form three intersection points, and the distance between any two intersection points is greater than the evaluation threshold, re-determine the collision contact point.

5. The measurement method according to claim 1, characterized in that, The spherical shell face mask is further provided with an operation handle, and the spherical shell face mask is rotated through the operation handle.

6. A measuring device for the collision contact point of a pedestrian protection headform impactor, characterized in that, The measurement device is used to implement the measurement method according to any one of claims 1-5, and the measurement device includes: A head impactor having an arc spherical surface; A cover plate provided with an impact target point, and the central axis of the head impactor is aligned with the impact target point so that the head impactor contacts the cover plate; and A spherical shell face mask, which is a hemispherical thin shell structure. A wedge portion is provided on the circumferential side of the end face of the spherical shell face mask. The wedge portion is a plane formed by the depression of the circumferential side of the end face and perpendicular to the diameter direction of the end face. The spherical shell face mask can fit and cooperate with the arc spherical surface of the head impactor and rotate relative to each other, so as to abut the wedge portion between the head impactor and the cover plate.

7. The measuring device according to claim 6, characterized in that, The plane of the wedge portion is tangent to the inner wall of the adjacent spherical shell face mask.

8. The measuring device according to claim 7, characterized in that, The central angle corresponding to the plane of the wedge portion is θ, the radius of the spherical shell face mask is R, and the maximum length dimension L of the plane of the wedge portion along its own radial direction is L = R×sinθ.

9. The measuring device according to claim 6, characterized in that, It further includes a circular marking sticker. A positioning hole opposite to the wedge portion is also provided on the circumferential side of the end face of the spherical shell face mask. The circular marking sticker is attached to the determined collision contact point of the head impactor through the positioning hole.

10. The measuring device according to claim 6, characterized in that, The spherical shell face mask is further provided with an operation handle, and the spherical shell face mask is rotated through the operation handle.

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