A Physical-Based Method, System and Device for Constructing Human-Induced Loads

Abstract

The present invention discloses a method, system and device for constructing human-induced loads based on physics. By synchronously testing the sole force and centroid acceleration of rhythmic movements, the parameters required in the human-induced load model are obtained, and the human-induced load is characterized from the perspective of physical movements, enabling this model to be directly applied in practice. On the one hand, the present invention only needs to obtain individual geometric parameters to reconstruct the human-induced load, taking into account the influence of factors such as height and body shape on dynamic effects, and realizing the differential description of different individuals. On the other hand, by deconstructing the movement process of the human-induced load, the present invention integrates all movement forms and makes a unified characterization.

Description

Technical Field

[0001] The present invention belongs to the technical field of human kinetics, and relates to a method, system and device for constructing human-induced loads based on physics, in particular to a method, system and device for constructing human-induced loads based on physics applicable to building structures. Background Art

[0002] More and more public buildings such as stadiums and music stands adopt large-span structures, which are characterized by light weight, low frequency and small damping. Such structures are sensitive to human-induced loads. Human-induced loads refer to the dynamic actions exerted on the supporting structure by the users of the building when performing actions such as walking, jumping, running, dancing, bouncing, sudden standing up / sitting down, going up and down stairs, etc. Such dynamic actions are likely to cause vibrations of large-span and lightweight engineering structures such as building floors, pedestrian bridges, long cantilever structures, stadium stands, and flexible stairs. In severe cases, they may lead to comfort and even safety problems of the structure. The human-induced load test method is a method for testing the dynamic actions exerted on the structure by the users during movement. A reliable human-induced load test method is a prerequisite for ensuring the accuracy of the vibration response analysis of human-induced loads on large-span structures.

[0003] Traditional human-induced load test methods are mostly deterministic test methods. Generally, the continuous walking (or jumping, bouncing) of pedestrians is regarded as a periodically repeated process, that is, it is assumed that each step (jump) is exactly the same, and then it is approximately expressed by Fourier series. Taking the walking load as an example, the dynamic action can be expressed as formula (1).

[0004]

[0005] In the formula: G is the static body weight of the human body, N is the order, a v0 is the mean value of the load time history, a vi is the coefficient of the i-th order Fourier series, generally called the dynamic load factor DLF, f p is the walking frequency, is the i-th order phase angle. Different motion forms will have different dynamic action f v (t) expressions. Such test methods characterize human-induced loads based on measured forces, which are pure mathematical methods. Therefore, they ignore the physical movement process of the human body and cannot reflect the influence brought by factors such as height and body shape. In addition, such methods cannot uniformly characterize all motion forms. Summary of the Invention

[0006] To solve the above technical problems, based on Newton's second law of motion, the present invention provides a physics-based method, system, and device for constructing human-induced loads. By establishing a physical model of human-induced loads, the dynamic effects of human-induced loads are characterized from the perspective of physical motion. On the one hand, the present invention only needs to obtain individual geometric parameters to reconstruct human-induced loads, taking into account the influence of factors such as height and body shape on dynamic effects, and realizing differential descriptions of different individuals. On the other hand, by deconstructing the motion process of human-induced loads, the present invention integrates all motion forms and makes a unified characterization.

[0007] The technical solution adopted by the method of the present invention is as follows: A physics-based method for constructing human-induced loads, comprising the following steps:

[0008] Step 1: Establish a human-induced load model based on physical motion;

[0009]

[0010] In the formula: f(t) is the dynamic effect of human-induced loads, G is the static body weight of the human body, α ∈ {0, 1} is a logical function, taking 1 for vertical loads and 0 for horizontal loads; m is the mass of the human body. In the static state of the human body, the mass and body weight satisfy the relationship G = mg; is the centroid acceleration during human motion. The value of R is related to the human motion mode and frequency. That is, for the same motion mode and frequency, the value of R is fixed;

[0011] Step 2: Without considering individual differences, use wearable sensing devices to obtain the mass participation coefficient R;

[0012] Step 3: Considering factors such as height and body shape, use wearable sensing devices to obtain the centroid acceleration

[0013] Step 4: Based on the above steps, complete the calibration of relevant parameters in the load model expression so that it can be directly applied in practice.

[0014] The technical solution adopted by the system of the present invention is as follows: A physics-based system for constructing human-induced loads, comprising the following modules:

[0015] Module 1, for establishing a human-induced load model based on physical motion;

[0016]

[0017] In the formula: f(t) is the dynamic effect of human-induced loads, G is the static body weight of the human body, α ∈ {0, 1} is a logical function, taking 1 for vertical loads and 0 for horizontal loads; m is the mass of the human body. In the static state of the human body, the mass and body weight satisfy the relationship G = mg; The acceleration of the center of mass during human movement, and R is the mass participation coefficient; for different movement modes and frequencies, the value of R will be different, but for the same movement mode and the same frequency, the value of R is fixed;

[0018] Module 2, for obtaining the mass participation coefficient R using a wearable sensing device without considering individual differences;

[0019] Module 3, for obtaining the acceleration of the center of mass using a wearable sensing device considering factors such as height and body shape

[0020] Module 4, for calibrating the relevant parameters in the load model expression based on the above modules so that it can be directly applied in practice.

[0021] The technical solution adopted by the device of the present invention is: a physics-based human-induced load construction device, including:

[0022] One or more processors;

[0023] A storage device for storing one or more programs, which when executed by the one or more processors cause the one or more processors to implement the above-mentioned physics-based human-induced load construction method.

[0024] Different from the traditional method of approximately characterizing human-induced loads in the form of Fourier series, the present invention is based on physical motion and obtains human-induced loads by acquiring the acceleration of the center of mass. It has the following advantages:

[0025] (1) During the actual movement of different individuals, affected by factors such as height and body shape, even when the masses are equal, the accelerations of the center of mass are not the same, and the load effects will also be different. Therefore, obtaining the dynamic effect of the load by acquiring the acceleration of the center of mass of the mover can reflect the influence of individual difference factors such as height and body shape.

[0026] (2) Integrating different movement forms (walking, jumping, running, dancing, bouncing, sudden standing up / sitting down, going up and down stairs, etc.), that is, applying the physical model of human-induced loads can represent all movement forms and obtain the dynamic effect of human-induced loads.

[0027] (3) Different from the traditional mathematical model of human-induced loads, the method of this patent only requires individual geometric parameters to reconstruct the plantar force. Description of the Drawings

[0028] Figure 1 It is a flowchart of the method according to an embodiment of the present invention;

[0029] Figure 2Schematic diagram of the bouncing motion according to an embodiment of the present invention;

[0030] Figure 3 Graph showing the relationship between R and frequency for the bouncing motion according to an embodiment of the present invention;

[0031] Figure 4 Schematic diagram of the bouncing motion parameters according to an embodiment of the present invention;

[0032] Figure 5 Graph showing the variation of θ1 and θ2 with frequency according to an embodiment of the present invention;

[0033] Figure 6 Schematic diagram of the comparison between the measured and fitted centroid displacements according to an embodiment of the present invention. Detailed implementation manners

[0034] To facilitate the understanding and implementation of the present invention by those of ordinary skill in the art, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0035] Please refer to Figure 1 , a method for constructing a human-induced load based on physics provided by the present invention includes the following steps:

[0036] Step 1: Establish a human-induced load model based on physical motion;

[0037] According to Newton's second law of motion, the inertial effect of the effective participating mass during human motion is the main source of dynamic load. The human-induced load model based on physical motion of the present invention can be represented by the unified formula (2).

[0038]

[0039] In the formula: f(t) is the dynamic action of the human-induced load, G is the static body weight of the human body, α ∈ {0, 1} is a logical function, taking 1 for vertical load and 0 for horizontal load; m is the mass of the human body. When the human body is in a static state, the mass and body weight satisfy the relationship G = mg; is the centroid acceleration during human motion, and R is the mass participation coefficient; for different motion modes and frequencies, the value of R will be different, but for the same motion mode and the same frequency, the value of R is fixed, that is, the individual differences are ignored. Thus, in the experiment, the value of R can be obtained by measuring the centroid acceleration and the dynamic action f(t) of the test subject under different motion forms.

[0040] Furthermore, according to the motion characteristics of the human body, when a person is in motion, the centroid displacement can be expressed by the following formula (3).

[0041]

[0042] Among them

[0043] In this way, the acceleration formula of the centroid can be expressed as Formula (4).

[0044]

[0045] where u1 and u2 respectively refer to the amplitudes of each order of Fourier series, ω0 refers to the circular frequency of the bouncing motion refers to the phase difference between the second-order Fourier series and the first-order. The above parameters can all be measured through experiments. Combining Formula (2) and Formula (4), the dynamic action expression of the human-induced load is as shown in Formula (5).

[0046]

[0047] where G and m are both measurable. In this way, after obtaining the correlation coefficients R, v i , ω0, the dynamic action of the human-induced load can be obtained. When obtaining the correlation coefficients v i , ω0, factors such as height and body shape are considered. Therefore, this model is also a physical model of the human-induced load.

[0048] Step 2: Taking the bouncing motion as an example, without considering individual differences, use wearable sensing devices to obtain the mass participation coefficient R;

[0049] Taking the bouncing motion as an example, see Figure 2 , the wearable sensing devices used in the present invention are force-measuring insoles (white dots in the figure) and acceleration sensors (black dots in the figure). Among them, the force-measuring insoles record the plantar force, that is, the dynamic action f(t) of the human-induced load, and the acceleration sensor measures the centroid acceleration during the human movement

[0050] Taking into account the sample representativeness (subjects' age, gender, height, weight, etc.) and sample size, several healthy adult individuals are selected to participate in the experiment. Fix the acceleration sensor at the position of the posterior lumbar spine of the subject (approximately considered as the human centroid), and the subject wears the force-measuring insoles. After the experiment starts, let the subject perform bouncing motions at different frequencies. The force-measuring insoles measure the plantar force of the subject, and the acceleration sensor synchronously measures the centroid acceleration data of the subject during the experiment. In this way, the centroid acceleration during the human movement and the dynamic action f(t) of the human-induced load can be obtained. Since both the plantar force and the centroid acceleration are continuous time history curves, the mass participation coefficient R is calculated using Formula (6).

[0051]

[0052] Where: F i is n1 representative values selected from the measured plantar force, i.e., the dynamic action f(t) of the human-induced load, a j is n2 representative values selected from the measured centroid acceleration , are the mean values of the selected plantar force and centroid acceleration respectively.

[0053] Different frequencies will correspond to different mass participation coefficients R obtained in the experiment. The specific relationship is as follows Figure 3 .

[0054] Step 3: Taking the bouncing motion as an example, considering factors such as height and body shape, obtain the centroid acceleration

[0055] After experimental attempts, only the first-order Fourier series is now used for fitting, and relatively accurate accuracy can also be obtained. At this time

[0056] u(t) = u1 sin(2πω0t) (7)

[0057] u1 = (1 - sinθ1)l1 + (1 - sinθ2)l2 (8)

[0058] Where: l1 and l2 respectively represent the lengths of the thigh and the calf, θ1 represents the maximum angle between the thigh and the counterclockwise rotation in the forward horizontal direction of the ground during the bouncing motion, and θ2 represents the minimum angle between the calf and the counterclockwise rotation in the forward horizontal direction of the ground during the bouncing motion.

[0059] After a large number of experiments, it is found that when the bouncing frequency is the same, for different subjects, the values of θ1 and θ2 are similar, as follows Figure 5 shown. Therefore, according to the fitting curve, when the bouncing frequency is given, the values of θ1 and θ2 can be directly obtained. The specific analytical formula after fitting is as follows

[0060] θ1 = -5ω0 + 122.9 (9)

[0061] θ2 = 13ω0 + 34.5 (10)

[0062] After actually measuring the lengths l1 and l2 of the thigh and the calf, the values of θ1 and θ2 can be obtained from formulas (9) and (10) according to the frequency ω0 of the motion load, so that the centroid displacement expression can be obtained according to formulas (7) and (8), and then the second derivative can be further obtained to get the centroid acceleration expression.

[0063] Next, using the previously completed experiment on capturing the displacement of the center of mass of human bouncing motion, a comparison graph of the displacement of the center of mass of the human body using the motion capture device and the established model is given. The following Figure 6 Schematic diagrams are given respectively with slower (2.2 Hz) and faster (3.0 Hz) as examples. Obviously, good accuracy can be obtained only by reconstructing with the first-order Fourier series.

[0064] The dynamic action expression of the human-induced load is obtained as:

[0065] f(t) = αG + Rm[v1 sin(2πω0t)] (11)

[0066] where G, m, R, v i can all be measured. For a given bouncing frequency ω0, the dynamic action of the human-induced load can be obtained through this formula.

[0067] Step 4: Based on the above steps, complete the calibration of the relevant parameters in the load model expression so that it can be directly applied in practice.

[0068] It should be understood that the above description of the preferred embodiment is relatively detailed, and it should not be considered as a limitation to the protection scope of the present invention patent. Under the inspiration of the present invention, those of ordinary skill in the art can also make substitutions or deformations without departing from the protection scope defined by the claims of the present invention, and all fall within the protection scope of the present invention. The scope of protection claimed by the present invention shall be subject to the appended claims.

Claims

1. A physics-based method for constructing human-induced loads, characterized in that, Including the following steps: Step 1: Establish a human-induced load model based on physical motion; ； In the formula: is the dynamic action of human-induced load, is the static body weight of the human body, is a logical function, taking 1 for vertical load and 0 for horizontal load; is the human body mass. In the state of human body rest, the mass and the body weight satisfy the relationship ; is the centroid acceleration during human movement, is the mass participation coefficient; The value of is related to the human movement mode and frequency. That is, for the same movement mode and frequency, the value of is fixed; Step 2: Without considering individual differences, obtain the quality participation coefficient using a wearable sensing device ; Step 3: Considering factors such as height and body type, obtain the centroid acceleration using wearable sensing devices ; Step 4: Based on the above steps, complete the calibration of relevant parameters in the load model expression so that it can be directly applied in practice.

2. The method for constructing a human-induced load based on physics according to claim 1, wherein The quality participation coefficient described in Step 2 is as follows: ； Wherein: is the measured plantar force, i.e., the dynamic action of the human-induced load selected as representative values, is the measured center-of-mass acceleration selected as representative values, and are the mean values of the selected plantar force and center-of-mass acceleration, respectively.

3. The method for constructing a human-induced load based on physics according to claim 1, characterized in that: In step 3, according to the movement characteristics of the human body, the displacement of the center of mass during human movement is as follows: ； Among them, is the amplitude of the first-order Fourier series, is the fundamental frequency of the bouncing motion; during the bouncing motion is: ； Wherein, and respectively represent the lengths of the thigh and the calf, represents the maximum angle between the counterclockwise rotation in the horizontal forward direction of the ground and the thigh during the bouncing motion, represents the minimum angle between the counterclockwise rotation in the horizontal forward direction of the ground and the calf during the bouncing motion; The acceleration of the centroid obtained thereby is: ； Among them , it is obtained by taking the second derivative based on the centroid displacement .

4. A physics-based human-induced load construction system, characterized in that, Including the following modules: Module 1, for establishing a human-induced load model based on physical motion; ； Wherein: is the dynamic action of the human-induced load, is the static body weight of the human body, is a logical function, taking 1 under vertical load and 0 under lateral load; is the human body mass. Under the static state of the human body, the mass and the body weight satisfy the relationship ; is the centroid acceleration during human movement, The value of is related to the human movement mode and frequency. That is, for the same movement mode and frequency, the value of is fixed; Module 2, for obtaining a quality participation coefficient using a wearable sensing device without considering individual differences ; Module 3, which is used to consider factors such as height and body type and obtain the centroid acceleration using a wearable sensing device ; Module 4, for completing the calibration of relevant parameters in the load model expression based on the above modules so that it can be directly applied in practice.

5. A physics-based human-induced load construction device, characterized in that, Including: One or more processors; A storage device for storing one or more programs, which when executed by the one or more processors, cause the one or more processors to implement the physics-based human-induced load construction method according to any one of claims 1 to 3.

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