Hierarchical solving method for virtual maintenance attitude of aircraft in narrow space

Abstract

The invention discloses a hierarchical solving method for a virtual maintenance attitude of an airplane in a narrow space, and the method comprises the steps: deeply analyzing a plurality of man-machine engineering factors which may affect an operation effect in the maintenance attitude, such as the movable range of each joint of a human body, the balance of the attitude, the comfort, the accessibility and the visibility; a multi-objective optimization model of a virtual maintenance posture is established for the upper body and the lower body for the complex factors. In consideration of special requirements of maintenance tasks in a narrow space, an optimization scheme of an upper body and a lower body is specially designed, so that the optimal operation effect can be achieved with the minimum body burden when maintenance personnel carry out maintenance operation, and secondly, an NSGA-II (non-dominated sorting genetic algorithm II) algorithm for improving a selection strategy is introduced. According to the algorithm, through an improved selection mechanism, an optimal solution can be more quickly converged in a multi-objective optimization process, so that the generation speed and accuracy of the maintenance attitude are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the field of aircraft virtual maintenance posture solution, and in particular, relates to a layered solution method for aircraft narrow space virtual maintenance posture. Background Art

[0002] Aircraft is a highly sophisticated and complex system consisting of many parts and systems, which requires regular maintenance to cope with wear and tear and failures in daily use. Due to the compact design of aircraft structure and narrow maintenance space, maintenance personnel are restricted in their activities when performing tasks, which increases the difficulty of work and safety risks. Therefore, the maintainability of the aircraft should be considered in the design stage, and the maintenance work should be simulated using virtual simulation technology. Maintainability analysis through virtual human models can help identify design defects of aircraft structure and system in advance and improve maintenance efficiency and safety. Quickly determining the appropriate virtual maintenance posture in a confined space is the primary problem to be solved in conducting maintainability virtual simulation, which is crucial to improving the efficiency and accuracy of maintainability analysis.

[0003] At present, most methods focus on virtual human arms or wide environments. For example, Wu Wei created a multi-objective optimization posture simulation model and used a multi-objective genetic algorithm to find the optimal posture of the virtual human arm [1]; Nguyen used a differential evolution algorithm with an improved search space to predict the joint angle values ​​of the arm [2]; Guo Qing used quaternions and inverse kinematics combined with a particle swarm algorithm to study the virtual human posture generation technology in civil aviation maintenance verification in a wide environment [3]. The above methods can generate virtual human postures for certain maintenance tasks. However, the overall posture of maintenance and the posture under the constraints of a small space have not been fully considered, which is still a challenge in the field of aircraft virtual maintenance posture solution technology.

[0004] [1]. Wu Weiwei, Ye Linmei, Shao Xiaodong, et al. Simulation of virtual human working posture based on multi-objective genetic algorithm[J]. Computer Integrated Manufacturing Systems, 2019, 25(01): 155-64.

[0005] [2].Trung Nguyen,Tam Bui,Ha Pham.Using proposed optimization algorithm for solving inverse kinematics of human upper limb applying inrehabilitation robotic[J].Artificial Intelligence Review, 2021,55(679-705.

[0006] [3]. Guo Qing, Ma Xinchen, Fu Yu. Virtual human posture generation technology for civil aviation maintenance work[J]. Computer Integrated Manufacturing Systems, 2023, 29(11): 3582-91.

[0007] In view of this, the present invention is proposed. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a layered solution method for virtual maintenance posture in a narrow space of an aircraft, thereby solving the problems raised in the above-mentioned background technology.

[0009] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0010] A method for solving a virtual maintenance posture hierarchical problem in a narrow space of an aircraft comprises the following steps:

[0011] Step 1: Obtain and analyze the human body structure and movement, and establish a virtual human structure model and a virtual human kinematic model based on the analysis data;

[0012] Step 2: Analyze the impact of ergonomic factors on maintenance posture, formulate maintenance posture constraint criteria, and construct corresponding indicator functions;

[0013] Step 3: Decompose the maintenance posture into upper body and lower body parts and construct maintenance posture multi-objective optimization models respectively;

[0014] Step 4: Solve the multi-objective optimization model established in step 3 in the order of upper body and lower body, so as to quickly obtain a reasonable maintenance posture suitable for a small space.

[0015] Optionally, the specific steps of constructing the virtual human structure model and kinematic model in step 1 are as follows:

[0016] A1: Simplify the human skeleton, joints, and degrees of freedom obtained and simplify the human body into a structure consisting of 14 rigid body segments with uniform mass and 14 joints;

[0017] A2: Based on the structural model, the virtual character is divided into three parts: upper limbs, head, neck and torso, and lower limbs. In order to describe the spatial relationship between these parts, a 4×4 homogeneous transformation matrix is ​​used to represent the spatial relationship between adjacent rigid body segments in the human body structure model. By considering the rotation angle of each joint and using continuous posture transformation, the position and direction of each part of the body are calculated.

[0018] A3: The homogeneous transformation matrix A represents the product of the rotation matrix and the displacement matrix between adjacent rigid body segments, and its expression is: A = R (θ x ,θ y ,θ z )·T(lx ,l y ,l z ), where R(θ x ,θ y ,θ z ) indicates that the rotation angles in the x, y, and z axes are θ respectively. x ,θ y ,θ z The rotation matrix, T(l x ,l y ,l z ) indicates that the displacements in the x, y, and z axes are l x , l y , l z The displacement matrix.

[0019] Optionally, the upper limb part in step A2 is composed of the upper arm, forearm and hand, including the shoulder joint, elbow joint and wrist joint. First, an absolute coordinate system O-xyz is established as the maintenance scene coordinate system, and then local coordinate systems are established in the upper arm, forearm and hand in turn, namely the shoulder joint coordinate system O sh -xyz, elbow joint coordinate system O el -xyz and wrist joint coordinate system O wr -xyz, according to the limitations of the human body structure, the three joints of the arm have a total of 7 degrees of freedom, among which the shoulder joint has 3 degrees of freedom, and the corresponding rotation angles are θ 1 sh ,θ 2 sh ,θ 3 sh ; The elbow joint has 1 degree of freedom, corresponding to the angle θ 1 el ; The wrist joint has three degrees of freedom, and the corresponding rotation angles are θ 1 wr ,θ 2 wr ,θ 3 wr .

[0020] The head, neck and trunk part consists of two parts, the head, neck and trunk, including the neck joint and waist joint. The head, neck and trunk motion model only considers the degrees of freedom perpendicular to the body plane, including two joints with a total of two rotational degrees of freedom. Among them, the neck joint coordinate system is One-xyz, which has one rotational degree of freedom, and the corresponding rotation angle is θ 1 ne ; The waist joint coordinate system is Owa-xyz, which has 1 degree of freedom of rotation, corresponding to the angle θ 1 wa .

[0021] The lower limbs consist of three parts: the thigh, the calf and the sole of the foot, including the hip joint, the knee joint and the ankle joint. When modeling, only the movement of the knee joint and the ankle joint in the plane perpendicular to the body is considered. Therefore, the lower limb motion model of the virtual human includes three joints with a total of four rotational degrees of freedom. Among them, the hip joint coordinate system is Ohi-xyz, which has two rotational degrees of freedom, and the corresponding rotation angle is θ 1 hi ,θ 2 hi ; The knee joint coordinate system is Okn-xyz, which has 1 degree of freedom of rotation, corresponding to the angle θ 1 kn ; The ankle joint coordinate system is Oan-xyz, which has 1 degree of freedom of rotation, corresponding to the angle θ 1 an

[0022] Optionally, the maintenance posture constraint criteria formulated in step 2 include a balance criterion, an accessibility criterion, a visibility criterion, and a joint comfort criterion;

[0023] The balance criterion is based on the relationship between the center of gravity of the human body and the support area. Specifically, the closer the projection point of the center of gravity is to the midpoint of the support area, the better the posture balance. The expression of the human posture balance index function is: in, is the distance between the midpoint of the support area and the projection point of the center of gravity of the human body, is the distance between the center point of the support area and the intersection point of the boundary, and the distance between the midpoint of the support area and the projection point of the center of gravity of the human body By formula Where (XG, YG) is the projection point P of the center of gravity of the human body in the plane of the support area. G The coordinates of (XA, YA) are the midpoint P of the human body support area. A The coordinates of

[0024] The accessibility criterion is evaluated by measuring the maximum reach of the palm end when the arm is extended. Whether the palm can touch the maintenance target point is used as the judgment basis of the accessibility criterion. Specifically, if the maintenance posture meets the accessibility criterion, the palm end should coincide with the maintenance target point. The expression of the human posture accessibility index function is: (x p ,y p ,z p )=(x a ,y a ,z a ), where (xp, yp, zp) represents the coordinates of the end of the palm, and (xa, ya, za) represents the coordinates of the maintenance target point.

[0025] The visibility criterion is that when the maintenance personnel observe the target point, the line of sight is within the best field of view and is not blocked by obstacles. The best field of view of a person is 15° above and below the normal field of view of a person. The expression of the visibility index function of the human body posture is: 0°≤β≤15°, where β represents the angle between the maintenance line of sight of the virtual person and the normal line of sight, and the maintenance line of sight refers to the line between the midpoint of the line connecting the virtual person's eyes and the target point.

[0026] The joint comfort criterion is to quantify the joint comfort through the ratio of joint torque to the maximum allowable joint torque. The expression of the joint comfort calculation function is: Among them, τ is the actual torque on a certain joint rotational degree of freedom, τ max is the maximum allowable torque on a joint's rotational degree of freedom.

[0027] Optionally, the comfort of different joints of the human body has different effects on the overall maintenance posture comfort, so different weights should be given when calculating the comfort of each part of the limb. For the joint comfort criterion in B4, the construction of the joint comfort index function is as follows:

[0028] The expression of the comprehensive comfort index function of the upper limb arm joint is: in, is the shoulder joint comfort calculation function; U el Calculate the function for elbow joint comfort; Function for calculating wrist joint comfort. is the comfort weight of the kth rotational degree of freedom of the shoulder joint; ω el Weight for elbow comfort; is the comfort weight of the mth rotational degree of freedom of the wrist joint (1≤m≤3);

[0029] The expression of the comprehensive comfort index function of the head, neck and trunk joints is: τ T =ω ne (U ne )+ω wa (U wa ), where U ne is the neck joint comfort calculation function, U wa is the waist joint comfort calculation function; ω ne is the comfort weight of the neck joint, ω wa is the waist joint comfort weight of the accessibility objective function;

[0030] The expression of the comprehensive comfort index of the lower limb joints is:

[0031] in, is the hip joint comfort calculation function; U kn is the knee joint comfort calculation function; U an Calculate the function for ankle comfort. is the comfort weight of the nth rotational degree of freedom of the hip joint (1≤n≤2); ω kn is the comfort weight of knee joint; ω an Weighted for ankle comfort.

[0032] Optionally, the specific steps for establishing the maintenance posture multi-objective optimization model in step 3 are as follows:

[0033] C1: Define the coordinate system of the virtual human posture model. Define the head direction of the virtual human when standing upright as the positive z-axis of the absolute coordinate system, the chest direction as the positive x-axis, and the left hand direction as the positive y-axis, so that the O-xy plane coincides with the ground. This coordinate system provides a basic framework for subsequent posture optimization;

[0034] For the upper body maintenance posture optimization model, the following factors are considered in turn:

[0035] C2: The primary task of the upper body posture is to ensure that the palm can reach the maintenance target point. According to the accessibility criterion, the coordinates of the target point should coincide with the coordinates of the palm end. The reachability objective function is established and its expression is: (x p ,y p ,z p )=(x a ,y a ,z a ), where (xp, yp, zp) represents the coordinates of the end of the palm, and (xa, ya, za) represents the coordinates of the maintenance target point;

[0036] C3: In order to ensure good sight during maintenance, it is necessary to ensure that the virtual person's maintenance sight is within the optimal human sight range. Therefore, a visibility objective function is established to ensure that the angle between the maintenance sight and the normal sight is within the range of 0°-15°. The expression is: 0°≤β=|θ 1 ne -15°-β vi |≤15°, where θ 1 ne represents the rotation angle of the neck joint, β represents the angle between the virtual person's maintenance line of sight and the normal line of sight, and β vi represents the angle between the virtual person's maintenance sight line and the horizontal line, and the angle β between the virtual person's maintenance sight line and the horizontal line vi The expression is: Among them, xy and zy represent the coordinate components of the midpoint of the binocular line in the x-axis and y-axis directions, and xa and za represent the coordinate components of the maintenance target point in the x-axis and z-axis directions;

[0037] C4: The range of motion of the human body is limited by its own structure, especially in the case of the upper body, the limit position of the waist joint is constrained. If the palm position remains unchanged, the limit position of the waist joint is constrained as follows:

[0038] ① X-axis direction: When the human body's waist bends forward until the torso is parallel to the horizontal plane and the arms are fully extended, the waist joint is at the farthest position from the target point; when the human body's torso is perpendicular to the horizontal plane and the arms and torso completely overlap, the waist joint is at the closest position to the target point.

[0039] ②y-axis direction: When the waist of the human body bends to the right until the trunk is parallel to the horizontal plane and the arms are fully extended, the waist joint is at the farthest position in the positive direction of the y-axis from the target point; when the waist of the human body bends to the left until the trunk is parallel to the horizontal plane and the arms are fully extended, the waist joint is at the farthest position in the negative direction of the y-axis from the target point;

[0040] ③ z-axis direction: When the human body stands with legs together and perpendicular to the ground, the waist joint is at the farthest position from the ground; when the human body sits on the ground, the waist joint is at the closest position to the ground, which is approximately 0. The expression of the human body structure constraint objective function is: Among them, (xa, ya, za) represents the coordinates of the maintenance target point, (xL, yL, zL) represents the coordinates of the waist joint point, l1, l2, l3 represent the lengths of the virtual person's upper arm, forearm and palm respectively, l4 represents the distance between the neck joint and the waist joint, l5 represents the vertical distance between the virtual person's waist joint and hip joint, l6, l7 represent the lengths of the thigh and calf respectively, and l8 represents the distance between the ankle joint and the heel.

[0041] C5: For the upper body maintenance posture optimization model, according to the joint comfort criterion, through the comprehensive comfort index of the upper limb arm part and the head, neck and trunk part, the expression of the upper body joint comfort objective function is: in, is the shoulder joint comfort calculation function, U el is the elbow joint comfort calculation function, is the wrist joint comfort calculation function, is the comfort weight of the kth rotational freedom of the shoulder joint (1≤k≤3), ω el Weight for elbow comfort, is the comfort weight of the mth rotational degree of freedom of the wrist joint (1≤m≤3), U ne is the calculation function of neck joint comfort; U wa ω is the waist joint comfort calculation function. ne is the comfort weight of the neck joint; ω wa Weight for waist joint comfort;

[0042] C6: Multi-objective optimization model of upper body maintenance posture based on C2-C5, which is expressed as: Among them, (x p ,y p , z p ) is the coordinate of the end of the palm, (x p ,y p , z p ) is the coordinate of the maintenance target point, is the rotation angle of the virtual human neck joint, is the angle between the maintenance sight line and the horizontal line, z a is the coordinate of the maintenance target point on the z-axis, y is the coordinate of the virtual person's head / eye on the z-axis, x a The coordinate of the target point for maintenance by Awei on the x-axis, x y The coordinates of my virtual person's head / eyes on the x-axis, x a ,y a , z a are the coordinates of the maintenance target point on the x, y, and z axes, respectively. 1 , l 2 , l 3 , l 4 are the lengths of the upper arm, forearm, palm, and shoulder joint to waist joint of the virtual person, respectively. 5 , l 6 , l 7 To represent the length of the virtual human's thigh and calf, and the distance between the ankle joint and the heel, and To optimize the objective function, a function used to describe the objectives of the maintenance posture (such as comfort, accessibility, visibility, etc.) is the comfort weight of the kth rotational degree of freedom of the shoulder joint, is the comfort calculation function of the kkkth rotational degree of freedom of the shoulder joint, w el is the comfort weight of the elbow joint, U el is the comfort calculation function of the elbow joint, is the comfort weight of the mth rotational degree of freedom of the wrist joint, is the comfort calculation function of the mth rotational degree of freedom of the wrist joint, w ne is the comfort weight of the neck joint, U ne is the comfort calculation function of the neck joint, ω wa is the comfort weight of the waist joint, U wa Function for calculating the comfort of waist joint.

[0043] Optionally, the steps for optimizing the model for lower body maintenance posture are:

[0044] C7: According to the balance criterion, the closer the projection point of the human body's center of gravity is to the center of the support area, the better the posture balance is. The expression of the balance objective function is: in, is the distance between the center of the support area and the projection point of the center of gravity of the human body, is the distance between the center point of the support area and the boundary intersection point;

[0045] C8: To ensure the safety and stability of maintenance work, assuming that the soles of the maintenance personnel's feet should be completely in contact with the ground, the expression of the spatial position constraint objective function is:

[0046] Among them, l8 and l9 represent the distance between the ankle joint and the heel, and between the heel and the toe, respectively; zn represents the z-axis component of the absolute coordinates of the ankle joint; zf represents the z-axis component of the absolute coordinates of the heel; and zt represents the z-axis component of the absolute coordinates of the toe; the expression for obtaining the z-axis component zn of the absolute coordinates of the ankle joint is: Among them, (xn,yn,zn) represents the absolute coordinates of the ankle joint, (xL,yL,zL) represents the absolute coordinates of the waist joint, is the transformation matrix between the hip joint coordinates and the waist joint coordinates, is the transformation matrix between knee joint coordinates and hip joint coordinates, Transformation matrix between ankle joint coordinates and knee joint coordinates;

[0047] C9: According to the joint comfort criterion, through the comprehensive comfort index of the lower limbs, the expression of the lower limb joint comfort objective function is: in,

[0048] C10: Based on C7-C9, the multi-objective optimization model of lower body maintenance posture is obtained, and its expression is:

[0049] Among them, z f is the z-axis coordinate of the heel, n is the z-axis coordinate of the ankle joint, l 8 To indicate the distance between the ankle joint and the heel, is the rotation angle of the ankle joint, z t is the z-axis coordinate of the toe, l 9 To express the distance between the heel and the toes, f bal To represent the balance objective function, we need to minimize, represents the distance between the midpoint of the support area (PAP_APA) and the projection point of the center of gravity of the human body (PGP_GPG), represents the distance between the midpoint of the support area and the boundary intersection (PBP_BPB), fTL represents the joint comfort objective function of the lower body, which also needs to be minimized. is the comfort weight of the nnnth rotational degree of freedom of the hip joint, is the comfort calculation function representing the nnnth rotational degree of freedom of the hip joint, ω kn is the comfort weight of the knee joint, U kn is the calculation function of the comfort of the knee joint, ω an To represent the comfort weight of the ankle joint, U an Calculate the function to represent the comfort of the ankle joint.

[0050] Optionally, a multi-objective optimization model of lower body maintenance posture is solved, and the specific steps are as follows:

[0051] D1: The individuals in the population are sorted from small to large according to their fitness values, and the selection probability is linearly assigned to each individual. The selection strategy of the NSGA-Ⅱ algorithm is improved by changing the selection probability. Among them, the selection probability P of individual j is j Assignment, the expression is: Where N is the population size, 1≤j≤N, γ + and γ - For x N and x 1 The expected value after the selection operation; and satisfy 0≤γ - ≤1,γ + =2-γ - , by changing γ + and γ - Two values, changing the probability of selection;

[0052] D2: According to the NSGA-Ⅱ algorithm with improved selection strategy in step D1, the maintenance posture multi-objective optimization model established in step 3 C6 and C10 is solved in the order of upper body and lower body, and finally the task of solving the virtual maintenance posture in the narrow space of the aircraft is completed.

[0053] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art. Of course, any product implementing the present invention does not necessarily need to achieve all the advantages described below at the same time:

[0054] The present invention deeply analyzes various ergonomic factors that may affect the operation effect in the maintenance posture, such as the movable range of each joint of the human body, the balance of the posture, comfort, accessibility and visibility, etc., and establishes a multi-objective optimization model of virtual maintenance posture for the upper body and the lower body respectively according to these complex factors. Considering the special needs of maintenance tasks in a small space, the present invention specially designs the optimization scheme of the upper body and the lower body, so that the maintenance personnel can achieve the best operation effect with the minimum physical burden when performing maintenance operations. Secondly, the present invention introduces the NSGA-Ⅱ (non-dominated sorting genetic algorithm II) algorithm with improved selection strategy. The algorithm can converge to the optimal solution more quickly in the multi-objective optimization process through an improved selection mechanism, thereby significantly improving the generation speed and accuracy of the maintenance posture. This efficient solution method is not only suitable for the virtual simulation of maintainability in the aircraft design stage, but also can provide strong support for the later maintenance task planning. The present invention solves the problem that the traditional method is difficult to efficiently generate a reasonable posture in a complex and restricted environment by quickly obtaining the optimal virtual maintenance posture in a small space, and provides a comprehensive and reliable technical guarantee for the design and maintenance of aircraft structures and systems. Through the application of this technology, the efficiency and feasibility of maintainability analysis have been significantly improved, thereby reducing the labor intensity of maintenance personnel and improving overall operational efficiency while ensuring flight safety.

[0055] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The drawings described below are only some embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0057] Figure 1 is a flow chart of the method of the present invention;

[0058] Figure 2 This is a diagram of the structure model of a virtual human according to the present invention;

[0059] Figure 3 This is a diagram of the arm movement model of a virtual human in the present invention;

[0060] Figure 4 This is a diagram of the virtual human head, neck and trunk motion model of the present invention;

[0061] Figure 5 This is a diagram of the lower limb motion model of a virtual human according to the present invention;

[0062] Figure 6 This is a maintenance posture model diagram of a virtual human in the present invention;

[0063] Figure 7 This is a maintenance environment diagram of an embodiment of the present invention;

[0064] Figure 8 This is a maintenance posture diagram of an embodiment of the present invention;

[0065] Fig. 9 This is a maintenance visibility assessment result diagram of an embodiment of the present invention;

[0066] Fig.10 This is a maintenance accessibility evaluation result diagram of an embodiment of the present invention;

[0067] Fig.11 This is a diagram of personnel comfort evaluation results according to an embodiment of the present invention.

[0068] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0069] The present invention will now be described in further detail with reference to the accompanying drawings.

[0070] See also Figure 1-11 As shown, this embodiment takes the cockpit ADM module disassembly task of a certain type of civil aircraft as an example, adopts a layered solution method for virtual maintenance posture in a narrow space of an aircraft proposed in the present invention, obtains the optimal maintenance posture in the maintenance scenario, and performs simulation verification through the MakeReal3D virtual simulation platform. Figure 1-11 As shown, the solution method is as follows:

[0071] Step 1: Obtain and analyze the human body structure and movement. Analyze the human body structure and establish a virtual human structure model by simplifying the human skeleton and joints. Figure 2 The simplified virtual human structure model shown includes 14 rigid body segments of uniform mass and 14 joints;

[0072] Based on the structural model, the DH method is used to establish the motion model of the virtual human. Figure 3 The virtual human arm motion model shown in the figure has 3 joints and 7 rotational degrees of freedom. Figure 4 The head-neck-torso motion model shown has 2 joints and 2 rotational degrees of freedom, as shown in Figure 5 The lower limb motion model shown has 3 joints and 4 rotational degrees of freedom;

[0073] Step 2: Analyze the impact of ergonomic factors on maintenance posture, formulate maintenance posture constraint criteria, and construct corresponding indicator functions;

[0074] The maintenance posture constraint criteria developed in step 2 include balance criteria, accessibility criteria, visibility criteria, and joint comfort criteria;

[0075] The balance criterion is based on the relationship between the center of gravity of the human body and the support area. Specifically, the closer the projection point of the center of gravity is to the midpoint of the support area, the better the posture balance. The expression of the human posture balance index function is: in, is the distance between the midpoint of the support area and the projection point of the center of gravity of the human body, is the distance between the center point of the support area and the intersection point of the boundary, and the distance between the midpoint of the support area and the projection point of the center of gravity of the human body By formula Where (XG, YG) is the projection point P of the center of gravity of the human body in the plane of the support area. G The coordinates of (XA, YA) are the midpoint P of the human body support area. A The coordinates of

[0076] The accessibility criterion is evaluated by measuring the maximum reach of the palm end when the arm is extended. Whether the palm can touch the maintenance target point is used as the judgment basis of the accessibility criterion. Specifically, if the maintenance posture meets the accessibility criterion, the palm end should coincide with the maintenance target point. The expression of the human posture accessibility index function is: (x p ,y p ,z p )=(x a ,y a ,z a ), where (xp, yp, zp) represents the coordinates of the end of the palm, and (xa, ya, za) represents the coordinates of the maintenance target point.

[0077] The visibility criterion is that when the maintenance personnel observe the target point, the line of sight is within the best field of view and is not blocked by obstacles. The best field of view of a person is 15° above and below the normal field of view of a person. The expression of the visibility index function of the human body posture is: 0°≤β≤15°, where β represents the angle between the maintenance line of sight of the virtual person and the normal line of sight, and the maintenance line of sight refers to the line between the midpoint of the line connecting the virtual person's eyes and the target point.

[0078] The joint comfort criterion is to quantify the joint comfort through the ratio of joint torque to the maximum allowable joint torque. The expression of the joint comfort calculation function is: Among them, τ is the actual torque on a certain joint rotational degree of freedom, τ max is the maximum allowable torque on a joint's rotational degree of freedom.

[0079] In this embodiment, the comfort of different joints of the human body has different effects on the overall maintenance posture comfort. Therefore, different weights should be given when calculating the comfort of each part of the limb. For the joint comfort criterion in B4, the construction of the joint comfort index function is as follows:

[0080] The expression of the comprehensive comfort index function of the upper limb arm joint is: in, U is the shoulder joint comfort calculation function; el Calculate the function for elbow joint comfort; Function for calculating wrist joint comfort. is the comfort weight of the kth rotational degree of freedom of the shoulder joint; ω el Weight for elbow comfort; is the comfort weight of the mth rotational degree of freedom of the wrist joint (1≤m≤3);

[0081] The expression of the comprehensive comfort index function of the head, neck and trunk joints is: τ T =ω ne (U ne )+ω wa (U wa ), where U ne is the neck joint comfort calculation function, U wa is the waist joint comfort calculation function; ω ne is the comfort weight of the neck joint, ω wa is the waist joint comfort weight of the accessibility objective function;

[0082] The expression of the comprehensive comfort index of the lower limb joints is:

[0083] in, is the hip joint comfort calculation function; U kn is the knee joint comfort calculation function; U an Calculates the function for ankle joint comfort. is the comfort weight of the nth rotational degree of freedom of the hip joint (1≤n≤2); ω kn is the comfort weight of knee joint; ω an Weighted for ankle comfort.

[0084] Step 3: If Figure 6 As shown in the figure, a maintenance posture model of a virtual human is established in the MakeReal3D simulation platform, and a multi-objective optimization model of the maintenance posture of the upper body and the lower body is constructed in layers with the waist as the dividing point;

[0085] C1: Define the coordinate system of the virtual human posture model. Define the head direction of the virtual human when standing upright as the positive z-axis of the absolute coordinate system, the chest direction as the positive x-axis, and the left hand direction as the positive y-axis, so that the O-xy plane coincides with the ground. This coordinate system provides a basic framework for subsequent posture optimization;

[0086] For the upper body maintenance posture optimization model, the following factors are considered in turn:

[0087] C2: The primary task of the upper body posture is to ensure that the palm can reach the maintenance target point. According to the accessibility criterion, the coordinates of the target point should coincide with the coordinates of the palm end. The reachability objective function is established and its expression is: (x p ,y p ,z p )=(x a ,y a ,z a ), where (xp, yp, zp) represents the coordinates of the end of the palm, and (xa, ya, za) represents the coordinates of the maintenance target point;

[0088] C3: In order to ensure good vision during maintenance, it is necessary to ensure that the virtual person's maintenance vision is within the optimal human vision range. Therefore, a visibility objective function is established to ensure that the angle between the maintenance vision and the normal vision is within the range of 0°-15°. Its expression is: in, represents the rotation angle of the neck joint, β represents the angle between the virtual person's maintenance line of sight and the normal line of sight, and β vi represents the angle between the virtual person's maintenance sight line and the horizontal line, and the angle β between the virtual person's maintenance sight line and the horizontal line vi The expression is: Among them, xy and zy represent the coordinate components of the midpoint of the binocular line in the x-axis and y-axis directions, and xa and za represent the coordinate components of the maintenance target point in the x-axis and z-axis directions;

[0089] C4: The range of motion of the human body is limited by its own structure, especially in the case of the upper body, the limit position of the waist joint is constrained. If the palm position remains unchanged, the limit position of the waist joint is constrained as follows:

[0090] ① X-axis direction: When the human body's waist bends forward until the torso is parallel to the horizontal plane and the arms are fully extended, the waist joint is at the farthest position from the target point; when the human body's torso is perpendicular to the horizontal plane and the arms and torso completely overlap, the waist joint is at the closest position to the target point.

[0091] ②y-axis direction: When the waist of the human body bends to the right until the trunk is parallel to the horizontal plane and the arms are fully extended, the waist joint is at the farthest position in the positive direction of the y-axis from the target point; when the waist of the human body bends to the left until the trunk is parallel to the horizontal plane and the arms are fully extended, the waist joint is at the farthest position in the negative direction of the y-axis from the target point;

[0092] ③ z-axis direction: When the human body stands with legs together and perpendicular to the ground, the waist joint is at the farthest position from the ground; when the human body sits on the ground, the waist joint is at the closest position to the ground, which is approximately 0. The expression of the human body structure constraint objective function is: Among them, (xa, ya, za) represents the coordinates of the maintenance target point, (xL, yL, zL) represents the coordinates of the waist joint point, l1, l2, l3 represent the lengths of the virtual person's upper arm, forearm and palm respectively, l4 represents the distance between the neck joint and the waist joint, l5 represents the vertical distance between the virtual person's waist joint and hip joint, l6, l7 represent the lengths of the thigh and calf respectively, and l8 represents the distance between the ankle joint and the heel.

[0093] C5: For the upper body maintenance posture optimization model, according to the joint comfort criterion, through the comprehensive comfort index of the upper limb arm part and the head, neck and trunk part, the expression of the upper body joint comfort objective function is: in, is the shoulder joint comfort calculation function, U el is the elbow joint comfort calculation function, is the wrist joint comfort calculation function, is the comfort weight of the kth rotational freedom of the shoulder joint (1≤k≤3), ω el Weight for elbow comfort, is the comfort weight of the mth rotational degree of freedom of the wrist joint (1≤m≤3), U ne is the calculation function of neck joint comfort; U wa ω is the waist joint comfort calculation function. ne is the comfort weight of the neck joint; ω wa Weight for waist joint comfort;

[0094] C6: Multi-objective optimization model of upper body maintenance posture based on C2-C5, which is expressed as: Among them, (x p ,y p , z p ) is the coordinate of the end of the palm, (x p ,y p , z p ) is the coordinate of the maintenance target point, is the rotation angle of the virtual human neck joint, is the angle between the maintenance sight line and the horizontal line, z a is the coordinate of the maintenance target point on the z-axis, y is the coordinate of the virtual person's head / eye on the z-axis, x a The coordinate of the target point of Awei's maintenance on the x-axis, x y The coordinates of my virtual person's head / eyes on the x-axis, xa ,y a , z a are the coordinates of the maintenance target point on the x, y, and z axes, respectively. 1 , l 2 , l 3 , l 4 are the lengths of the upper arm, forearm, palm, and shoulder joint to waist joint of the virtual person, respectively. 5 , l 6 , l 7 To represent the length of the virtual human's thigh and calf, and the distance between the ankle joint and the heel, and To optimize the objective function, a function used to describe the objectives of the maintenance posture (such as comfort, accessibility, visibility, etc.) is the comfort weight of the kkkth rotational degree of freedom of the shoulder joint, is the comfort calculation function of the kkkth rotational degree of freedom of the shoulder joint, ω el is the comfort weight of the elbow joint, U el is the comfort calculation function of the elbow joint, is the comfort weight of the mth rotational degree of freedom of the wrist joint, is the comfort calculation function of the mth rotational degree of freedom of the wrist joint, ω ne is the comfort weight of the neck joint, U ne is the comfort calculation function of the neck joint, ω wa is the comfort weight of the waist joint, U wa Function for calculating the comfort of waist joint.

[0095] The steps for optimizing the model for lower body maintenance posture are:

[0096] C7: According to the balance criterion, the closer the projection point of the human body's center of gravity is to the center of the support area, the better the posture balance is. The expression of the balance objective function is: in, is the distance between the center of the support area and the projection point of the center of gravity of the human body, is the distance between the center point of the support area and the boundary intersection point;

[0097] C8: To ensure the safety and stability of maintenance work, assuming that the soles of the maintenance personnel's feet should be completely in contact with the ground, the expression of the spatial position constraint objective function is:

[0098] Among them, l8 and l9 represent the distance between the ankle joint and the heel, and between the heel and the toe, respectively; zn represents the z-axis component of the absolute coordinates of the ankle joint; zf represents the z-axis component of the absolute coordinates of the heel; and zt represents the z-axis component of the absolute coordinates of the toe; the expression for obtaining the z-axis component zn of the absolute coordinates of the ankle joint is: Among them, (xn,yn,zn) represents the absolute coordinates of the ankle joint, (xL,yL,zL) represents the absolute coordinates of the waist joint, is the transformation matrix between the hip joint coordinates and the waist joint coordinates, is the transformation matrix between knee joint coordinates and hip joint coordinates, Transformation matrix between ankle joint coordinates and knee joint coordinates;

[0099] C9: According to the joint comfort criterion, through the comprehensive comfort index of the lower limbs, the expression of the lower limb joint comfort objective function is: in,

[0100] C10: Based on C7-C9, the multi-objective optimization model of lower body maintenance posture is obtained, and its expression is:

[0101] Among them, z f is the z-axis coordinate of the heel, n is the z-axis coordinate of the ankle joint, l 8 To indicate the distance between the ankle joint and the heel, is the rotation angle of the ankle joint, z t is the z-axis coordinate of the toe, l 9 To express the distance between the heel and the toes, f bal To represent the balance objective function, we need to minimize, represents the distance between the midpoint of the support area (PAP_APA) and the projection point of the center of gravity of the human body (PGP_GPG), represents the distance between the midpoint of the support area and the boundary intersection (PBP_BPB), fTL represents the joint comfort objective function of the lower body, which also needs to be minimized. is the comfort weight of the nnnth rotational degree of freedom of the hip joint, is the comfort calculation function representing the nnnth rotational degree of freedom of the hip joint, ω kn is the comfort weight of the knee joint, U kn is the calculation function of the comfort of the knee joint, ω an To represent the comfort weight of the ankle joint, U an Calculate the function to represent the comfort of the ankle joint.

[0102] like Figure 7 As shown, an aircraft cockpit structure model of the embodiment is created in the MakeReal3D simulation platform, wherein the ADM module to be disassembled is located inside the left front side of the captain's panel, and its absolute coordinates are (734.0 mm, 422.0 mm, 772.0 mm).

[0103] In the embodiment, the 50% percentile male of 18-45 years old in my country is taken as an example, and with reference to "Human Dimensions of Chinese Adults" and "Inertia Parameters of Adult Human Body", the specific parameters such as human body dimensions, body segment mass and center of mass position used in the application example are shown in Table 2. With reference to the "Human Engineering Design Manual for Military Equipment and Facilities" and human anatomy and physiology, the maximum and optimal range of motion of the rotational freedom of each joint of the human body within the normal physiological activity range is shown in Table 3.

[0104] Table 1:

[0105] body Measuring ruler quality Centroid measurement Center of mass head 231 5.16 Head Vertex 117.8 Body 1692 27 Cervical Point 293.4 superior 316 1.46 Radial point 163.3 forward 239 0.75 Radial stem 136.6 hand 184 0.38 Middle finger 114.2 big 470 8.5 Shin point 254.5 Small 374 2.2 Medial ankle point 224.1 foot 249 0.89 Sole 38.2

[0106] Table 2:

[0107]

[0108]

[0109] Step 4: Solve the multi-objective optimization model established in step 3 in the order of upper body and lower body, so as to quickly obtain a reasonable maintenance posture suitable for a small space.

[0110] D1: The individuals in the population are sorted from small to large according to their fitness values, and the selection probability is linearly assigned to each individual. The selection strategy of the NSGA-Ⅱ algorithm is improved by changing the selection probability. Among them, the selection probability P of individual j is j Assignment, the expression is: Where N is the population size, 1≤j≤N, γ + and γ - For x N and x 1 The expected value after the selection operation; and satisfy 0≤γ - ≤1,γ + =2-γ - , by changing γ + and γ - Two values, changing the probability of selection;

[0111] D2: According to the NSGA-Ⅱ algorithm with improved selection strategy in step D1, the maintenance posture multi-objective optimization model established in step 3 C6 and C10 is solved in the order of upper body and lower body, and the optimal Pareto solution set can be obtained;

[0112] The above optimal Pareto solution set is not a unique solution, so an optimal solution should be selected from the solution set as the optimal virtual maintenance posture for solving the problem in a narrow space. The selection of the optimal solution refers to the hierarchical analysis method, that is, the scale values ​​between indicators and their weights are determined according to the relative importance of the indicators. Table 1 is a proportional scale table.

[0113] Table 3:

[0114]

[0115]

[0116] In this embodiment, the specific steps of constructing the virtual human structure model and kinematic model in step 1 are as follows:

[0117] A1: Simplify the human skeleton, joints, and degrees of freedom obtained and simplify the human body into a structure consisting of 14 rigid body segments with uniform mass and 14 joints;

[0118] A2: Based on the structural model, the virtual character is divided into three parts: upper limbs, head, neck and torso, and lower limbs. In order to describe the spatial relationship between these parts, a 4×4 homogeneous transformation matrix is ​​used to represent the spatial relationship between adjacent rigid body segments in the human body structure model. By considering the rotation angle of each joint and using continuous posture transformation, the position and direction of each part of the body are calculated.

[0119] A3: The homogeneous transformation matrix A represents the product of the rotation matrix and the displacement matrix between adjacent rigid body segments, and its expression is: A = R (θ x ,θ y ,θ z )·T(l x ,l y ,l z ), where R(θ x ,θ y ,θ z ) indicates that the rotation angles in the x, y, and z axes are θ respectively. x ,θ y ,θ z The rotation matrix, T(l x ,l y ,l z ) indicates that the displacements in the x, y, and z axes are l x , l y , l z The displacement matrix.

[0120] In this embodiment, the upper limb part in step A2 is composed of the upper arm, forearm and hand, including the shoulder joint, elbow joint and wrist joint. First, an absolute coordinate system O-xyz is established as the maintenance scene coordinate system, and then local coordinate systems are established in the upper arm, forearm and hand in turn, namely the shoulder joint coordinate system O sh -xyz, elbow joint coordinate system O el -xyz and wrist joint coordinate system O wr-xyz, according to the limitations of the human body structure, the three joints of the arm have a total of seven degrees of freedom: the shoulder joint has 3 degrees of freedom, and the corresponding angles are The elbow joint has 1 degree of freedom of rotation, and the corresponding rotation angle is The wrist joint has three degrees of freedom, and the corresponding rotation angles are

[0121] The head, neck and trunk part consists of two parts, the head, neck and trunk, including the neck joint and waist joint. The head, neck and trunk motion model only considers the degrees of freedom perpendicular to the body plane, including two joints with a total of two rotational degrees of freedom. The neck joint coordinate system is O ne -xyz, which has 1 degree of freedom of rotation, corresponding to the angle θ 1 ne ; The waist joint coordinate system is O wa -xyz, which has 1 degree of freedom of rotation, corresponding to the angle θ 1 wa .

[0122] The lower limbs consist of three parts: the thigh, the calf and the sole of the foot, including the hip joint, the knee joint and the ankle joint. When modeling, only the movement of the knee joint and the ankle joint in the plane perpendicular to the body is considered. Therefore, the lower limb motion model of the virtual human includes three joints with a total of four rotational degrees of freedom. Among them, the hip joint coordinate system is Ohi-xyz, which has two rotational degrees of freedom, and the corresponding rotation angle is θ 1 hi ,θ 2 hi ; The knee joint coordinate system is Okn-xyz, which has 1 degree of freedom of rotation, corresponding to the angle θ 1 kn ; The ankle joint coordinate system is Oan-xyz, which has 1 degree of freedom of rotation, corresponding to the angle θ 1 an

[0123] In this embodiment, in the algorithm parameter setting, the population size is 100, the maximum number of iterations is 200, the crossover probability is 0.8, and the mutation probability is 0.05. The algorithm is used to solve the upper body posture multi-objective optimization model constructed in S3 to obtain the optimal Pareto solution set of the upper body posture.

[0124] Referring to the analytic hierarchy process, under the premise of ensuring accessibility and visibility, the joint comfort of the trunk is relatively more important than the joint comfort of the arm, and its scale value is 3, so the weights are set to 0.75 and 0.25 respectively. Based on this principle, the optimal solution in the Pareto solution set is selected to obtain the optimal angle values ​​of each joint of the upper body, which are:

[0125] According to the upper body rotation angle and ADM module coordinates obtained above, combined with the virtual human motion model, the absolute coordinates of the waist joint can be obtained: (-366.0mm, 456.7mm, 687.4mm).

[0126] According to the multi-objective optimization model of the lower body constructed in step 3, the improved NSGA-II algorithm is also used to solve the optimal Pareto solution set of the upper body posture. Referring to the hierarchical analysis method, the balance of maintenance personnel is relatively more important than the comfort of the lower limb joints, and its scale value is 3, so the weights are set to 0.75 and 0.25 respectively. Based on this principle, the optimal solution in the Pareto solution set is selected to obtain the optimal angle values ​​of each joint of the lower body, which are:

[0127] like Figure 8 As shown, in the Makereal3D virtual simulation platform, the joint angles and positions of the virtual human are set according to the above results, and the maintenance posture of the virtual human in the maintenance scene can be obtained.

[0128] like Fig. 9 The figure shows the results of the maintenance visibility assessment, where the cone area emitted from the virtual human's eyes represents the optimal field of view, and the binocular vision window is given in the upper left corner. Fig. 9 It can be seen that the ADM module is in a visible state and is within the optimal field of view of both eyes.

[0129] Fig.10 This is the maintenance reachability evaluation result, where the interior of the sphere centered on the virtual human shoulder joint represents the reachable area of ​​the hand. Fig.10 It can be seen that the ADM module is located within the accessible area, allowing barrier-free maintenance operations.

[0130] Fig.11 is the personnel comfort evaluation result, in which the personnel comfort in the maintenance posture is evaluated by the RULA evaluation method. Fig.11 It can be seen that the overall evaluation value of the whole body is 3, which is a relatively comfortable posture. In this posture, the virtual human's arms, cervical spine, lumbar spine and lower limbs are all in a relatively comfortable state.

[0131] The present invention is not limited to the above-mentioned embodiments. Anyone should be aware that any structural changes made under the enlightenment of the present invention, and any technical solutions that are the same or similar to the present invention, fall within the protection scope of the present invention. The technology, shape, and structural parts not described in detail in the present invention are all well-known technologies.

Claims

1. A hierarchical solution method for virtual maintenance posture in a small space of an aircraft. It is characterized in that The following steps are involved: Step 1: Obtain and analyze the human body structure and movement, and establish a virtual human structure model and a virtual human kinematic model based on the analysis data; Step 2: Analyze the impact of ergonomic factors on maintenance posture, formulate maintenance posture constraint criteria, and construct corresponding indicator functions; Step 3: Decompose the maintenance posture into upper body and lower body parts and construct maintenance posture multi-objective optimization models respectively; Step 4: Solve the multi-objective optimization model established in step 3 in the order of upper body and lower body, so as to quickly obtain a reasonable maintenance posture suitable for a small space.

2. According to the method for solving the virtual maintenance posture in a narrow space of an aircraft in a hierarchical manner in claim 1, It is characterized in that The specific steps for constructing the virtual human structure model and kinematic model in step 1 are as follows: A1: Simplify the human skeleton, joints, and degrees of freedom obtained and simplify the human body into a structure consisting of 14 rigid body segments with uniform mass and 14 joints; A2: Based on the structural model, the virtual character is divided into three parts: upper limbs, head, neck and torso, and lower limbs. In order to describe the spatial relationship between these parts, a 4×4 homogeneous transformation matrix is ​​used to represent the spatial relationship between adjacent rigid body segments in the human body structure model. By considering the rotation angle of each joint and using continuous posture transformation, the position and direction of each part of the body are calculated. A3: The homogeneous transformation matrix A represents the product of the rotation matrix and the displacement matrix between adjacent rigid body segments, and its expression is: A = R (θ x ,θ y ,θ z )·T(l x ,l y ,l z ), where R(θ x ,θ y ,θ z ) indicates that the rotation angles in the x, y, and z axes are θ respectively. x ,θ y ,θ z The rotation matrix, T(l x ,l y ,l z ) indicates that the displacements in the x, y, and z axes are l x , l y , l z The displacement matrix.

3. According to claim 2, a method for solving the virtual maintenance posture layering in a narrow space of an aircraft, It is characterized in that The upper limb part in step A2 consists of the upper arm, forearm and hand, including the shoulder joint, elbow joint and wrist joint. First, establish the absolute coordinate system O-xyz as the maintenance scene coordinate system, and then establish the local coordinate system in the upper arm, forearm and hand, that is, the shoulder joint coordinate system O sh -xyz, elbow joint coordinate system O el -xyz and wrist joint coordinate system O wr -xyz, according to the limitations of the human body structure, the three joints of the arm have a total of 7 degrees of freedom, among which the shoulder joint has 3 degrees of freedom, and the corresponding rotation angles are θ 1 sh , The elbow joint has 1 degree of freedom of rotation, and the corresponding rotation angle is The wrist joint has three degrees of freedom, and the corresponding rotation angles are θ 1 wr , The head, neck and trunk are composed of two parts, the head, neck and trunk, including the neck joint and waist joint. The head, neck and trunk motion model only considers the degrees of freedom perpendicular to the body plane, including two joints with a total of two rotational degrees of freedom. Among them, the neck joint coordinate system is One-xyz, which has one rotational degree of freedom, and the corresponding rotation angle is The waist joint coordinate system is Owa-xyz, which has 1 degree of freedom of rotation, and the corresponding angle is The lower limbs consist of three parts: the thigh, the calf and the sole of the foot, including the hip joint, the knee joint and the ankle joint. When modeling, only the movement of the knee joint and the ankle joint in the plane perpendicular to the body is considered. Therefore, the lower limb motion model of the virtual human includes three joints with a total of four rotational degrees of freedom. Among them, the hip joint coordinate system is 0hi-xyz, which has two rotational degrees of freedom, and the corresponding rotation angle is The knee joint coordinate system is Okn-xyz, which has 1 degree of freedom of rotation, and the corresponding angle is The ankle joint coordinate system is Oan-xyz, which has 1 degree of freedom of rotation, and the corresponding angle is 4. According to claim 1, a method for solving the virtual maintenance posture in a narrow space of an aircraft in a hierarchical manner, It is characterized in that The maintenance posture constraint criteria developed in step 2 include balance criteria, accessibility criteria, visibility criteria, and joint comfort criteria; The balance criterion is based on the relationship between the center of gravity of the human body and the support area. Specifically, the closer the projection point of the center of gravity is to the midpoint of the support area, the better the posture balance. The expression of the human posture balance index function is: in, is the distance between the midpoint of the support area and the projection point of the center of gravity of the human body, is the distance between the center point of the support area and the intersection point of the boundary, and the distance between the midpoint of the support area and the projection point of the center of gravity of the human body By formula Where (XG, YG) is the projection point P of the center of gravity of the human body in the plane of the support area. G The coordinates of (XA, YA) are the midpoint P of the human body support area. A The coordinates of The accessibility criterion is evaluated by measuring the maximum reach of the palm end when the arm is extended. Whether the palm can touch the maintenance target point is used as the judgment basis of the accessibility criterion. Specifically, if the maintenance posture meets the accessibility criterion, the palm end should coincide with the maintenance target point. The expression of the human posture accessibility index function is: (x p ,y p ,z p )=(x a ,y a ,z a ), where (xp, yp, zp) represents the coordinates of the end of the palm, and (xa, ya, za) represents the coordinates of the maintenance target point. The visibility criterion is that when the maintenance personnel observe the target point, the line of sight is within the best field of view and is not blocked by obstacles. The best field of view of a person is 15° above and below the normal field of view of a person. The expression of the visibility index function of the human body posture is: 0°≤β≤15°, where β represents the angle between the maintenance line of sight of the virtual person and the normal line of sight, and the maintenance line of sight refers to the line between the midpoint of the line connecting the virtual person's eyes and the target point. The joint comfort criterion is to quantify the joint comfort through the ratio of joint torque to the maximum allowable joint torque. The expression of the joint comfort calculation function is: Among them, τ is the actual torque on a certain joint rotational degree of freedom, τ max is the maximum allowable torque on a joint's rotational degree of freedom.

5. According to claim 4, a method for solving the virtual maintenance posture layering in a narrow space of an aircraft, It is characterized in that The comfort of different joints of the human body has different effects on the overall maintenance posture comfort. Therefore, different weights should be given when calculating the comfort of each part of the limb. According to the joint comfort criterion in B4, the construction of the joint comfort index function is as follows: The expression of the comprehensive comfort index function of the upper limb arm joint is: in, U is the shoulder joint comfort calculation function; el Calculate the function for elbow joint comfort; Function for calculating wrist joint comfort. is the comfort weight of the kth rotational degree of freedom of the shoulder joint; ω el Weight for elbow comfort; is the comfort weight of the mth rotational degree of freedom of the wrist joint (1≤m≤3); The expression of the comprehensive comfort index function of the head, neck and trunk joints is: τ T =ω ne (U ne )+ω wa (U wa ), where U ne is the neck joint comfort calculation function, U wa is the waist joint comfort calculation function; ω ne is the comfort weight of the neck joint, ω wa is the waist joint comfort weight of the accessibility objective function; The expression of the comprehensive comfort index of the lower limb joints is: in, is the hip joint comfort calculation function; U kn is the knee joint comfort calculation function; U an Calculate the function for ankle comfort. is the comfort weight of the nth rotational degree of freedom of the hip joint (1≤n≤2); ω kn is the comfort weight of knee joint; ω an Weighted for ankle comfort.

6. According to claim 1, a method for solving the virtual maintenance posture layering in a narrow space of an aircraft, It is characterized in that The specific steps for establishing the maintenance posture multi-objective optimization model in step 3 are as follows: C1: Define the coordinate system of the virtual human posture model. Define the head direction of the virtual human when standing upright as the positive z-axis of the absolute coordinate system, the chest direction as the positive x-axis, and the left hand direction as the positive y-axis, so that the O-xy plane coincides with the ground. This coordinate system provides a basic framework for subsequent posture optimization; For the upper body maintenance posture optimization model, the following factors are considered in turn: C2: The primary task of the upper body posture is to ensure that the palm can reach the maintenance target point. According to the accessibility criterion, the coordinates of the target point should coincide with the coordinates of the palm end. The reachability objective function is established and its expression is: (x p ,y p ,z p )=(x a ,y a ,z a ), where (xp, yp, zp) represents the coordinates of the end of the palm, and (xa, ya, za) represents the coordinates of the maintenance target point; C3: In order to ensure good sight during maintenance, it is necessary to ensure that the virtual person's maintenance sight is within the optimal human field of vision. Therefore, a visibility objective function is established to ensure that the angle between the maintenance sight and the normal sight is within the range of 0°-15°. Its expression is: in, represents the rotation angle of the neck joint, β represents the angle between the virtual person's maintenance line of sight and the normal line of sight, and β vi represents the angle between the virtual person's maintenance sight line and the horizontal line, and the angle between the virtual person's maintenance sight line and the horizontal line β vi The expression is: Among them, xy and zy represent the coordinate components of the midpoint of the binocular line in the x-axis and y-axis directions, and xa and za represent the coordinate components of the maintenance target point in the x-axis and z-axis directions; C4: The range of motion of the human body is limited by its own structure, especially in the case of the upper body, the limit position of the waist joint is constrained. If the palm position remains unchanged, the limit position of the waist joint is constrained as follows: ① X-axis direction: When the human body's waist bends forward until the torso is parallel to the horizontal plane and the arms are fully extended, the waist joint is at the farthest position from the target point; when the human body's torso is perpendicular to the horizontal plane and the arms and torso completely overlap, the waist joint is at the closest position to the target point. ②y-axis direction: When the waist of the human body bends to the right until the trunk is parallel to the horizontal plane and the arms are fully extended, the waist joint is at the farthest position in the positive direction of the y-axis from the target point; when the waist of the human body bends to the left until the trunk is parallel to the horizontal plane and the arms are fully extended, the waist joint is at the farthest position in the negative direction of the y-axis from the target point; ③ z-axis direction: When the human body stands with legs together and perpendicular to the ground, the waist joint is at the farthest position from the ground; when the human body sits on the ground, the waist joint is at the closest position to the ground, which is approximately 0. The expression of the human body structure constraint objective function is: Among them, (xa, ya, za) represents the coordinates of the maintenance target point, (xL, yL, zL) represents the coordinates of the waist joint point, l1, l2, l3 represent the lengths of the virtual person's upper arm, forearm and palm respectively, l4 represents the distance between the neck joint and the waist joint, l5 represents the vertical distance between the virtual person's waist joint and hip joint, l6, l7 represent the lengths of the thigh and calf respectively, and l8 represents the distance between the ankle joint and the heel. C5: For the upper body maintenance posture optimization model, according to the joint comfort criterion, through the comprehensive comfort index of the upper limb arm part and the head, neck and trunk part, the expression of the upper body joint comfort objective function is: in, is the shoulder joint comfort calculation function, U el is the elbow joint comfort calculation function, is the wrist joint comfort calculation function, is the comfort weight of the kth rotational freedom of the shoulder joint (1≤k≤3), ω el Weight for elbow comfort, is the comfort weight of the mth rotational degree of freedom of the wrist joint (1≤m≤3), U ne is the calculation function of neck joint comfort; U wa ω is the waist joint comfort calculation function. ne is the comfort weight of the neck joint; ω wa Weight for waist joint comfort; C6: Multi-objective optimization model of upper body maintenance posture based on C2-C5, which is expressed as: Among them, (x p ,y p , z p ) is the coordinate of the end of the palm, (x p ,y p , z p ) is the coordinate of the maintenance target point, is the rotation angle of the virtual human neck joint, is the angle between the maintenance sight line and the horizontal line, z a is the coordinate of the maintenance target point on the z-axis, y is the coordinate of the virtual person's head / eye on the z-axis, x a The coordinate of the target point for maintenance by Awei on the x-axis, x y The coordinates of my virtual person's head / eyes on the x-axis, x a ,y a , z a are the coordinates of the maintenance target point on the x, y, and z axes, respectively. 1 , l 2 , l 3 , l 4 are the lengths of the upper arm, forearm, palm, and shoulder joint to waist joint of the virtual person, respectively. 5 , l 6 , l 7 To represent the length of the virtual human's thigh and calf, and the distance between the ankle joint and the heel, and To optimize the objective function, a function used to describe the objectives of the maintenance posture (such as comfort, accessibility, visibility, etc.) is the comfort weight of the kth rotational degree of freedom of the shoulder joint, is the comfort calculation function of the kkkth rotational degree of freedom of the shoulder joint, ω el is the comfort weight of the elbow joint, U el is the comfort calculation function of the elbow joint, is the comfort weight of the mth rotational degree of freedom of the wrist joint, is the comfort calculation function of the mth rotational degree of freedom of the wrist joint, ω ne is the comfort weight of the neck joint, U ne is the comfort calculation function of the neck joint, ω wa is the comfort weight of the waist joint, U wa Function for calculating the comfort of waist joint.

7. The method for solving the virtual maintenance posture in a narrow space of an aircraft according to claim 6, It is characterized in that The steps for optimizing the model for lower body maintenance posture are: C7: According to the balance criterion, the closer the projection point of the human body's center of gravity is to the center of the support area, the better the posture balance is. The expression of the balance objective function is: in, is the distance between the center of the support area and the projection point of the center of gravity of the human body, is the distance between the center point of the support area and the boundary intersection point; C8: To ensure the safety and stability of maintenance work, assuming that the soles of the maintenance personnel's feet should be completely in contact with the ground, the expression of the spatial position constraint objective function is: Among them, l8 and l9 represent the distance between the ankle joint and the heel, and between the heel and the toe, respectively; zn represents the z-axis component of the absolute coordinates of the ankle joint; zf represents the z-axis component of the absolute coordinates of the heel; and zt represents the z-axis component of the absolute coordinates of the toe; the expression for obtaining the z-axis component zn of the absolute coordinates of the ankle joint is: Among them, (xn,yn,zn) represents the absolute coordinates of the ankle joint, (xL,yL,zL) represents the absolute coordinates of the waist joint, is the transformation matrix between the hip joint coordinates and the waist joint coordinates, is the transformation matrix between knee joint coordinates and hip joint coordinates, Transformation matrix between ankle joint coordinates and knee joint coordinates; C9: According to the joint comfort criterion, through the comprehensive comfort index of the lower limbs, the expression of the lower limb joint comfort objective function is: in, C10: Based on C7-C9, the multi-objective optimization model of lower body maintenance posture is obtained, and its expression is: Among them, z f is the z-axis coordinate of the heel, n is the z-axis coordinate of the ankle joint, l 8 To indicate the distance between the ankle joint and the heel, is the rotation angle of the ankle joint, z t is the z-axis coordinate of the toe, l 9 To express the distance between the heel and the toes, f bal To represent the balance objective function, we need to minimize, represents the distance between the midpoint of the support area (PAP_APA) and the projection point of the center of gravity of the human body (PGP_GPG), represents the distance between the midpoint of the support area and the boundary intersection (PBP_BPB), fTL represents the joint comfort objective function of the lower body, which also needs to be minimized. is the comfort weight of the nnnth rotational degree of freedom of the hip joint, is the comfort calculation function representing the nnnth rotational degree of freedom of the hip joint, ω kn is the comfort weight of the knee joint, U kn is the calculation function of the comfort of the knee joint, ω an is the comfort weight of the ankle joint, U an Calculate the function to represent the comfort of the ankle joint.

8. According to claim 1, a method for solving the virtual maintenance posture layering in a narrow space of an aircraft, It is characterized in that The multi-objective optimization model of lower body maintenance posture is solved. The specific steps are as follows: D1: The individuals in the population are sorted from small to large according to their fitness values, and a selection probability is linearly assigned to each individual. The selection strategy of the NSGA-II algorithm is improved by changing the selection probability. The selection probability P of individual j is j Assignment, the expression is: Where N is the population size, 1≤j≤N, γ + and γ - For x N and x 1 The expected value after the selection operation; and satisfy 0≤γ - ≤1,γ + =2-γ - , by changing γ + and γ - Two values, changing the probability of selection; D2: According to the NSGA-II algorithm with improved selection strategy in step D1, the maintenance posture multi-objective optimization model established in step 3 C6 and C10 is solved in the order of upper body and lower body, and finally the task of solving the virtual maintenance posture in the narrow space of the aircraft is completed.

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