A different percentile dummy head motion trajectory prediction method

Abstract

The application provides a different percentile dummy head movement trajectory prediction method, which performs collision analysis on N different percentile dummy head movement curves and seat arrangement environments, determines whether the dummy collides with the aircraft structure, selects different percentile dummy head movement trajectory prediction HIC test severe conditions, and performs impact test seat HIC test. Through the application, the cost of purchasing and assembling test benches, aircraft structural components, test dummies and other test pieces is reduced, time is saved, economic cost is reduced, seat development efficiency is improved, and a new idea is provided for airworthiness regulation compliance verification of the aircraft seat.

Description

Technical Field

[0001] This invention belongs to the field of impact strength design and verification technology, and in particular relates to a method for predicting the head motion trajectory of a dummy at different percentiles. Background Technology

[0002] Since head injuries are the primary cause of death in aviation accidents, civil aviation authorities in various countries have clearly defined head injury criteria (HIC) in their regulations to ensure aircraft cabin safety. Generally, testing is used to verify the HIC compliance of aircraft seats. Due to the complex environment inside the aircraft cabin, HIC testing has high requirements and is subject to many unpredictable factors. Therefore, predicting the head movement trajectory of HIC test dummies is essential to protect occupants and reduce head injury from impacts.

[0003] Currently, experimental methods are mainly used to demonstrate compliance, but the varying states of the seats lead to low efficiency and poor economy. Therefore, screening the seat for the most severe conditions using HIC testing before actual testing can improve testing efficiency and shorten the seat design cycle. Traditional dynamic simulation analysis methods lack model accuracy verification, and the characteristics of dummies (multi-degree-of-freedom rigid bodies) and seats (statically indeterminate) make it difficult to guarantee the accuracy of simulation analysis. To improve the efficiency of HIC testing, it is necessary to predict and analyze the head motion trajectories of dummies at different percentiles, thereby improving the overall structural performance and economic benefits of the seat.

[0004] In conclusion, research on the prediction of head movement trajectories of dummy at different percentiles is very important. Summary of the Invention

[0005] This invention provides a method for predicting the head motion trajectory of a dummy at different percentiles, providing experimental basis for seat HIC tests, solving the problem of low accuracy in simulation analysis due to lack of model accuracy verification, improving accuracy, and reducing test costs and cycle time. The technical solution is as follows: A method for predicting the head motion trajectory of a dummy at different percentiles is proposed. Collision analysis is performed on the head motion curves of the dummy at N different percentiles and the seat arrangement environment to determine whether the dummy collides with the aircraft structure. The harsh conditions of the HIC test are predicted by selecting different percentile dummy head motion trajectories, and the HIC test of the impact test seat is carried out. N is greater than or equal to 3.

[0006] The method includes the following steps: Step S1: Install the test dummy and adjust its posture. Conduct a horizontal impact test according to the test procedures of the general aviation aircraft seat performance standards. The test uses a 50th percentile dummy. Step S2: Obtain the 50th percentile dummy head motion data based on the experimental results of Step S1; Step S3: Import the 50th percentile dummy head motion data into the model diagram of the cockpit or cabin seating arrangement environment to obtain the 50th percentile dummy head motion curve. Step S4: Based on the difference between the 50th percentile and 5th percentile human body dimensions in the standard human body dimensions of Chinese male pilots, estimate the head motion curve of the 5th percentile dummy. Step S5: Based on the difference between the 50th and 95th percentile human body dimensions in the standard human body dimensions for Chinese male pilots, estimate the head motion curve of the 95th percentile dummy. Step S6: Perform collision analysis on the obtained head motion curves of the dummy at three different percentiles and the seat arrangement environment to determine whether the dummy collides with the aircraft structure and obtain the HIC severe test conditions under horizontal impact of the seat. Step S7: Conduct the HIC test on the impact test seat based on the severe test conditions obtained in Step S6.

[0007] In step S1, a horizontal impact test is conducted on the aviation seat according to the AC25.562-1B Dynamic Evaluation Method for Transportation Category Aircraft Seat Systems; specifically: Installation of test dummies: The test used a FAA Hybrid III 50th percentile male dummy; Adjust the dummy's posture according to the parameters that affect the impact test collision, including the seat back angle, armrest position, footrest installation position, shoulder strap position, and seat height; Marking points were attached to the dummy's head to measure the head's movement trajectory and speed; The horizontal impact test was conducted in accordance with the standard test procedures for the performance of general aviation aircraft seats.

[0008] In step S2, the results of step S1 are processed to obtain the three-dimensional coordinates of the head marker points, and the longitudinal displacement time curve, lateral displacement time curve, and vertical displacement time curve of the dummy head are obtained, which are the three-dimensional relative motion trajectory data of the dummy head.

[0009] In step S3, the three-dimensional relative motion trajectory data of the dummy's head obtained from the experiment is imported into the model diagram of the cockpit or cockpit seat layout environment to generate the 50th percentile dummy head motion curve C. 50 .

[0010] In step S4, the body size standards for different percentiles of Chinese male pilots are found, including the 50th percentile eye height (H) of pilots in seated posture. 50 And the horizontal distance from the eye position to the seat reference point is L. 50The 5th percentile pilot's seated eye height is H5, and the horizontal distance from the eye position to the seat reference point is L5; when the 5th percentile pilot's eye position coincides with the searched eye position, proportionally... For curve C 50 Scale the image and then translate the starting point to the eye position to obtain the 5th percentile pilot head motion curve C5.

[0011] In step S5, the standard anatomy of Chinese male pilots is found, including the 95th percentile eye height (H) in seated position. 95 And the horizontal distance from the eye position to the seat reference point is L. 95 When the 95th percentile pilot's eye position coincides with the searched eye position, it will be calculated proportionally. For curve C 50 Scale the image, then shift the starting point to the eye location to obtain the 95th percentile pilot head motion curve C. 95 .

[0012] In step S6, based on the obtained curve C 50 Curve C5, Curve C 95 The digital model of the seat layout environment was assembled to determine the distance between the pilot's head and the fuselage structure at different percentiles, thus obtaining curve C for the most dangerous head impact scenario. sev This refers to the head impact curve under the most severe working conditions.

[0013] In step S7, the 50th percentile pilot head impact curve C is first determined. 50 Head impact curve C under the most severe working conditions sev The relative positional relationship, analyze curve C 50 Curve C sev The point P closest to the structure in the seating arrangement environment 50 Point P sev The longitudinal and vertical positional relationship of the seat is determined; then the actual adjustment distances of the seat relative to the seat neutral position reference point forward and downward are calculated; finally, the most stringent conditions of the seat horizontal impact test are simulated according to the actual adjustment distances, and the HIC test is carried out.

[0014] In step S7, point P is recorded. 50 and point P sev The absolute value of the longitudinal position difference is 'a', and the absolute value of the vertical position difference is 'b'; calculate the forward and backward adjustment distances. , In order to make The smallest non-negative integer not less than a; calculate the vertical adjustment distance. , In order to make The smallest non-negative integer not less than b; c is the front and rear adjustment level, and d is the up and down adjustment level.

[0015] The beneficial effects of this invention are as follows: This invention proposes a method for predicting the head motion trajectory of dummies at different percentiles. By obtaining the head motion curves of dummies at different percentiles, it assesses the most severe collision injury to the head of a dummy in an aircraft cabin layout, providing experimental basis for seat HIC (High-Intensity Compatibility) testing. Since HIC testing is a destructive test, this method reduces the cost of purchasing and assembling test benches, aircraft structural components, test dummies, and other test materials, significantly saving time and economic costs, improving the efficiency of seat development, and providing a new approach to verifying the airworthiness compliance of aircraft seats. Attached Figure Description

[0016] Figure 1 Flowchart of the method for predicting head motion trajectories of dummy at different percentiles; Figure 2 A diagram showing the trajectory of the dummy's head movement. Figure 3 This is a schematic diagram showing the longitudinal and vertical positional relationships. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0019] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited from each other.

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] One embodiment of the present invention provides a method for predicting the head motion trajectory of a dummy at different percentiles. The method performs collision analysis on the head motion curves of the dummy at N different percentiles and the seat arrangement environment to determine whether the dummy collides with the aircraft structure. The method predicts the severe conditions of the HIC test by selecting different percentile dummy head motion trajectories and conducts the impact test seat HIC (Head Injury Criterion) test, where N is greater than or equal to 3.

[0022] A method for predicting the head motion trajectory of a dummy at different percentiles may specifically include the following steps: 1. Install the test dummy and adjust the seat and dummy's posture. Conduct a horizontal impact test according to the test procedures of the general aviation aircraft seat performance standards. The test uses a 50th percentile dummy.

[0023] The aircraft seat was subjected to a horizontal impact test according to the AC25.562-1B method for dynamic evaluation of transportation category aircraft seat systems. Based on previous test experience, the dummy's head movement was more severe under the horizontal impact test. Specifically: Installation of test dummies: The test used a FAA Hybrid III 50th percentile male dummy; Based on the parameters that affect the impact test collision, adjust the dummy's posture, including the seat back angle, armrest position, footrest installation position, shoulder strap position, and seat height; Marking points were attached to the head of the dummy, and the head movement trajectory and speed were measured using a high-speed camera photogrammetry system. The horizontal impact test was conducted in accordance with the standard test procedures for the performance of general aviation aircraft seats.

[0024] 2. Obtain head motion data of the 50th percentile dummy; Using specialized experimental data processing software, the results of step 1 were processed to obtain the three-dimensional coordinates of the head markers, resulting in the longitudinal displacement time curve, lateral displacement time curve, and vertical displacement time curve of the dummy head, which are the three-dimensional relative motion trajectory data of the dummy head, and also the 50th percentile dummy head motion data.

[0025] 3. Import the 50th percentile dummy head motion data into the model diagram of the cockpit or cabin seating arrangement environment to obtain the 50th percentile dummy head motion curve. The three-dimensional relative motion trajectory data of the dummy's head obtained from the experiment is imported into the model diagram of the cockpit or cockpit seat layout environment to generate the 50th percentile dummy head motion curve C. 50 .

[0026] 4. Based on the difference between the 50th percentile and 5th percentile anthropometric dimensions of Chinese male pilots, estimate the head motion curve of the 5th percentile dummy. Find the anthropometric standards for different percentiles of male pilots in China, including the 50th percentile eye height (H) in seated position for male pilots. 50 And the horizontal distance from the eye position to the seat reference point is L. 50 The 5th percentile pilot's eye height in seated position is H5, and the horizontal distance from the eye position to the seat reference point is L5. When the 5th percentile pilot's eye position coincides with the searched eye position, the seat needs to be adjusted upwards and forwards relative to the seat neutral position reference point. (Proportional) For curve C 50 Scale the image and then translate the starting point to the eye position to obtain the 5th percentile pilot head motion curve C5.

[0027] This step estimates the 5th percentile dummy head motion curve based on the difference between the 50th and 5th percentile anthropometric dimensions in relevant standards for Chinese male pilots. By identifying the difference between the 50th and 5th percentile anthropometric dimensions in relevant standards for Chinese male pilots, a scaling factor is calculated, and the 50th percentile dummy head motion curve is scaled and translated to obtain the 5th percentile dummy head motion curve.

[0028] 5. Based on the difference between the 50th and 95th percentile human body dimensions in the standard human body dimensions of Chinese male pilots, estimate the head motion curve of the 95th percentile dummy. Find the anatomy standards for Chinese male pilots, including the 95th percentile eye height (H) in seated position. 95 And the horizontal distance from the eye position to the seat reference point is L. 95 When the 95th percentile pilot's eye position coincides with the search eye position, the seat needs to be adjusted downwards and backwards relative to the seat neutral position reference point; proportionally For curve C 50 Scale the image, then shift the starting point to the eye location to obtain the 95th percentile pilot head motion curve C. 95 .

[0029] This step estimates the 95th percentile dummy head motion curve based on the difference between the 50th and 95th percentile anthropometric dimensions in relevant standards for Chinese male pilots. By identifying the difference between the 50th and 95th percentile anthropometric dimensions in relevant standards for Chinese male pilots, a scaling factor is calculated. The 50th percentile dummy head motion curve is then scaled and translated to obtain the 95th percentile dummy head motion curve.

[0030] 6. Collision analysis was performed on the obtained head motion curves of the dummy at three different percentiles and the seat arrangement environment to determine whether the dummy collided with the aircraft structure and to obtain the HIC severe test conditions under horizontal impact of the seat. Based on the obtained curve C 50 Curve C5, Curve C 95 Using software such as CATIA, a digital model of the seat layout environment was assembled to determine the distance between the pilot's head and the fuselage structure at different percentiles, thus obtaining the curve C for the most dangerous head impact scenario. sev This refers to the head impact curve under the most severe operating conditions. See Figure 2 and... Figure 3 .

[0031] The airworthiness regulations require that the HIC value not exceed 1000, and the Head Injury Criterion (HIC) is determined by the following formula:

[0032] in: t1 — Initial integration time (seconds); t2 — Integration termination time (seconds); a(t) — The curve showing the relationship between the total acceleration of the head impact and time (a is expressed as a multiple of g).

[0033] First, determine the spatial distance between the three curves and the aircraft cockpit structure to assess the risk of collision. If none of the three types of 100-man dummies' heads collide with the structure, select the curve with the head closest to the structure, and use the dummy in this posture as the severe test condition. If one of the 100-man dummies has a high risk of colliding with the structure, use the dummy in this posture as the severe test condition. The stiffness of the collision area after a collision directly affects the HIC value. Adjusting the attitude of the test dummy and estimating the collision point to be the point of maximum structural stiffness is the key to meeting the requirements of the HIC test.

[0034] 7. Based on the severe test conditions obtained in step 6, conduct the HIC test on the impact test seat, compare the test results with the analysis of the selected test conditions, and verify the accuracy of the test data.

[0035] First, determine the 50th percentile pilot head impact curve C. 50 Head impact curve C under the most severe working conditions sev The relative positional relationship, analyze curve C 50 C sev The point P closest to the structure in the seating arrangement environment 50 P sev The longitudinal and vertical positional relationship, generally speaking, P 50 P sev The lateral position changes are small and have little impact on the experimental analysis.

[0036] Next, calculate the actual forward and downward adjustment distances of the seat relative to the seat neutral position reference point; Finally, the most stringent HIC test was conducted to simulate the horizontal impact test of the seat based on the actual adjustment distance.

[0037] Specifically: Record point P 50 and P sev The absolute value of the longitudinal position difference is a (in mm), and the absolute value of the vertical position difference is b (in mm).

[0038] When conducting HIC tests using a 50th percentile dummy, the actual forward and downward adjustment distances of the seat relative to the seat neutral position reference point are calculated, and the most stringent conditions of the seat horizontal impact test are simulated according to the actual adjustment distances to conduct HIC tests.

[0039] When conducting HIC tests using a 50th percentile dummy, curve C needs to be adjusted to simulate the most severe working conditions during the test. 50 From P 50 Translate to P sev Given the seat's fore-aft adjustment increments c (in mm) and heel-to-hip adjustment increments d (in mm), where c and d are known, the seat was tested according to curve C. sev The relative position of the seating arrangement with the surrounding structure allows for adjustment of the distance forward and backward as needed. (mm), In order to make The smallest non-negative integer not less than a (depending on the actual situation, if a and a are not less than a) Extremely close, that is You can consider choosing According to curve C sev The relative position of the seating arrangement to the structure in the environment allows for vertical adjustment of the distance as needed. (mm), where, In order to make The smallest non-negative integer not less than b (depending on the actual situation, if b is greater than b) Extremely close, that is You can consider choosing .

[0040] According to the test standards, the seat is adjusted forward and backward (e) (mm) and downward and vertically (f) (mm) to simulate the most severe conditions of the seat horizontal impact test and to conduct the HIC test.

[0041] This step involves adjusting the seat's vertical and forward / backward distances to verify the test results based on the stringent HIC testing conditions.

[0042] The changes in the head motion curves of the dummy at different percentiles obtained in this embodiment can provide experimental basis for the test work during the seat HIC test.

[0043] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Furthermore, any parts of the present invention not described in detail are conventional techniques.

Claims

1. A method for predicting the head motion trajectory of a dummy at different percentiles, characterized in that, Includes the following steps: Step S1: Install the test dummy and adjust its posture. Conduct a horizontal impact test according to the test procedures of the general aviation aircraft seat performance standards. The test uses a 50th percentile dummy. Step S2: Obtain the 50th percentile dummy head motion data based on the experimental results of Step S1; Step S3: Import the 3D relative motion trajectory data of the dummy head obtained from the experiment into the model diagram of the cockpit or cockpit seat layout environment, and generate the 50th percentile dummy head motion curve C. 50 ; Step S4: Find the anthropometric standards for different percentiles of Chinese male pilots' body dimensions, including the 50th percentile eye height (H) in seated posture for pilots. 50 And the horizontal distance from the eye position to the seat reference point is L. 50 The 5th percentile pilot's seated eye height is H5, and the horizontal distance from the eye position to the seat reference point is L5; when the 5th percentile pilot's eye position coincides with the searched eye position, proportionally... For curve C 50 Scale the curve and then translate the starting point to the eye position to obtain the 5th percentile pilot head motion curve C5. Step S5: Find the standard body dimensions for Chinese male pilots, and the 95th percentile eye height (H) of pilots in seated posture. 95 And the horizontal distance from the eye position to the seat reference point is L. 95 When the 95th percentile pilot's eye position coincides with the searched eye position, it will be calculated proportionally. For curve C 50 Scale the image, then shift the starting point to the eye location to obtain the 95th percentile pilot head motion curve C. 95 ; Step S6: Perform collision analysis on the obtained head motion curves of the dummy at three different percentiles and the seat arrangement environment to determine whether the dummy collides with the aircraft structure and obtain the HIC severe test conditions under horizontal impact of the seat. Step S7: Conduct the HIC test on the seat based on the severe test conditions obtained in Step S6.

2. The method according to claim 1, characterized in that, In step S1, a horizontal impact test is conducted on the aviation seat according to the AC25.562-1B method for dynamic evaluation of transport category aircraft seat systems; specifically: Installation of test dummies: The test used a FAA Hybrid III 50th percentile male dummy; Adjust the dummy's posture according to the parameters that affect the impact test collision, including the seat back angle, armrest position, footrest installation position, shoulder strap position, and seat height; Marking points were attached to the dummy's head to measure the head's movement trajectory and speed; The horizontal impact test was conducted in accordance with the standard test procedures for the performance of general aviation aircraft seats.

3. The method according to claim 1, characterized in that, In step S2, the results of step S1 are processed to obtain the three-dimensional coordinates of the head marker points, and the longitudinal displacement time curve, lateral displacement time curve, and vertical displacement time curve of the dummy head are obtained, which are the three-dimensional relative motion trajectory data of the dummy head.

4. The method according to claim 1, characterized in that, In step S6, based on the obtained curve C 50 Curve C5, Curve C 95 The digital model of the seat layout environment was assembled to determine the distance between the pilot's head and the fuselage structure at different percentiles, thus obtaining curve C for the most dangerous head impact scenario. sev This refers to the head impact curve under the most severe working conditions.

5. The method according to claim 4, characterized in that, In step S7, the 50th percentile pilot head impact curve C is first determined. 50 Head impact curve C under the most severe working conditions sev The relative positional relationship, analyze curve C 50 Curve C sev The point P closest to the structure in the seating arrangement environment 50 Point P sev The longitudinal and vertical positional relationship; Next, calculate the actual forward and downward adjustment distances of the seat relative to the seat neutral position reference point; finally, simulate the most stringent conditions of the seat horizontal impact test according to the actual adjustment distances and conduct the HIC test.

6. The method according to claim 5, characterized in that, In step S7, record point P. 50 and point P sev The absolute value of the longitudinal position difference is 'a', and the absolute value of the vertical position difference is 'b'; calculate the forward and backward adjustment distances. , In order to make The smallest non-negative integer not less than a; calculate the vertical adjustment distance. , In order to make The smallest non-negative integer not less than b; c is the front and rear adjustment level, and d is the up and down adjustment level.

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