CN113331825A - Real-time RULA evaluation method in virtual reality - Google Patents

Real-time RULA evaluation method in virtual reality Download PDF

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CN113331825A
CN113331825A CN202110600585.0A CN202110600585A CN113331825A CN 113331825 A CN113331825 A CN 113331825A CN 202110600585 A CN202110600585 A CN 202110600585A CN 113331825 A CN113331825 A CN 113331825A
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姚寿文
王瑀
栗丽辉
胡子然
孔若思
兰泽令
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Beijing Institute of Technology BIT
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Abstract

The invention provides a real-time RULA evaluation method in virtual reality, which comprises the steps of collecting action frames, establishing a space coordinate system based on the action frames, extracting joint point coordinates based on the space coordinate system, and acquiring each limb vector based on the joint point coordinates; acquiring a main sagittal plane and a correction sagittal plane based on the joint point coordinates and the coordinate axis in the space coordinate system; acquiring main scores of all limbs and corrected scores of all limbs based on the vectors of all limbs, the main sagittal plane and the corrected sagittal plane; and obtaining total scores of all the limbs based on the main scores of all the limbs and the corrected scores of all the limbs, and obtaining the RULA scores of the human body postures through the RULA worksheet based on the total scores of all the limbs. The RULA evaluation method provided by the invention realizes quick, real-time and accurate evaluation of human-computer work efficiency.

Description

Real-time RULA evaluation method in virtual reality
Technical Field
The invention relates to the technical field of artificial machine effect evaluation, in particular to a real-time RULA evaluation method in virtual reality.
Background
Man-machine ergonomic design has important significance for industrial production, product quality, production cost, worker safety and the like, and human factors need to be considered in industrial product design urgently. The traditional ergonomic method is that engineers use a Digital Human Model (DHM) in CAM software to perform ergonomic evaluation on assembly designs. However, CAM software works less efficiently, is less accurate, and lacks real-time performance. Engineers need to adjust the limbs, the visual field and the like of the DHM, make a large number of key frames, are very complex and cumbersome, and lack realism and immersion. Therefore, improvement of a human-machine work efficiency evaluation method based on DHM is urgently needed, and rapidity, instantaneity and accuracy of evaluation are improved through a virtual reality technology.
The RULA rapid upper limb analysis model in DHM ergonomic assessment methods is currently a common ergonomic assessment method. In the field of mechanical industry, human-computer work efficiency evaluation is mainly realized by subjectively observing or estimating human joint angles in pictures or videos, which requires inviting experts in the field to spend a lot of time on posture analysis, and rapid, real-time and accurate evaluation of human-computer work efficiency of an RULA model cannot be realized.
Disclosure of Invention
In order to solve the problem that the conventional RULA model in the prior art cannot be evaluated quickly, timely and accurately, the invention provides a real-time RULA evaluation method in virtual reality, which comprises the following steps:
acquiring an action frame, establishing a space coordinate system based on the action frame, extracting joint point coordinates based on the space coordinate system, and acquiring each limb vector based on the joint point coordinates;
acquiring a main sagittal plane and a correction sagittal plane based on the joint point coordinates and the coordinate axis in the space coordinate system;
projecting each limb vector to the main sagittal plane to obtain a main projection vector of each limb vector, and obtaining each limb main angle of each limb vector on the main sagittal plane according to the main projection vector; acquiring main scores of all limbs based on the main angles of all limbs;
projecting each limb vector to the correction sagittal plane to obtain the correction projection vector of each limb vector, and obtaining the correction angle of the limb vector on the correction sagittal plane according to the correction projection vector; obtaining correction scores of all limbs based on the correction angles;
and obtaining total scores of all the limbs based on the main scores of all the limbs and the corrected scores of all the limbs, and obtaining the RULA scores of the human body postures through the RULA worksheet based on the total scores of all the limbs.
Preferably, the joint point coordinates include caudal vertebra coordinates, neck coordinates, head coordinates, left shoulder coordinates, right shoulder coordinates, left elbow coordinates, right elbow coordinates, left wrist coordinates, right wrist coordinates, left hand coordinates, right hand coordinates, left hip coordinates, right hip coordinates, and shoulder vertebra coordinates.
Preferably, the limb vectors include a torso vector, a neck vector, a right upper arm vector, a left upper arm vector, a right front arm vector, a left forearm vector, a right wrist vector, and a left wrist vector.
Preferably, the specific step of obtaining the major sagittal plane includes:
and acquiring a main sagittal plane based on a shoulder vertebra coordinate, a left shoulder coordinate and a right shoulder coordinate, wherein the shoulder vertebra coordinate is positioned on the main sagittal plane, and a vector pointing to the right shoulder coordinate from the left shoulder coordinate is a normal vector of the main sagittal plane.
Preferably, the modified sagittal planes include a first modified sagittal plane, a second modified sagittal plane, and a third modified sagittal plane;
the first correction sagittal plane is used for calculating a body torsion correction score and a neck torsion correction score based on each limb vector;
the second correction sagittal plane is used for calculating a lateral bending correction score of the trunk based on each limb vector;
and the third correction sagittal plane is used for calculating a neck lateral bending correction score, an upper arm lateral bending correction score and a forearm lateral bending correction score based on the limb vectors.
Preferably, the specific step of obtaining the first modified sagittal plane includes:
and acquiring the first modified sagittal plane based on an x axis and a y axis in the space coordinate system, wherein the x axis and the y axis in the space coordinate system are positioned on the first modified sagittal plane.
Preferably, the specific step of obtaining the second modified sagittal plane includes:
and acquiring the second correction sagittal plane based on the left hip coordinate, the right hip coordinate and the coordinate axis in the space coordinate system, wherein the left hip coordinate and the right hip coordinate are positioned on the second correction sagittal plane, and the y axis in the space coordinate system is parallel to the second correction sagittal plane.
Preferably, the specific step of obtaining the third modified sagittal plane includes:
and acquiring the third correction sagittal plane based on the trunk vector, the left shoulder coordinate and the right shoulder coordinate, wherein the trunk vector is positioned on the third correction sagittal plane, and a vector pointing to the right shoulder coordinate from the left shoulder coordinate and a vector cross-multiplied by the trunk vector are normal vectors of the third correction sagittal plane.
Preferably, the specific step of obtaining the primary score of each limb includes:
calculating projection vectors of all the limb vectors on a normal vector of the main sagittal plane, calculating main projection vectors of all the limb vectors on the main sagittal plane through the projection vectors, then calculating included angles among the main projection vectors of all the limb vectors to obtain main angles of all the limb vectors, and matching corresponding scores of the main angles in an RULA working table to obtain main scores of all the limbs.
Preferably, the specific steps of obtaining the correction score of each limb based on the correction angle are as follows:
and acquiring the posture factors under the current correction angle based on the correction angle, and obtaining the correction score of each limb by matching the corresponding correction score of the posture factors in the RULA working table.
Compared with the prior art, the invention has the following effects:
according to the method, the main sagittal plane is constructed, the sagittal plane is corrected, the limb vectors are projected to each sagittal plane, then the angle calculation of the projection vectors is carried out, and the score judgment is carried out by combining with the RULA worksheet, so that the RULA score of the test posture can be obtained, manual data manufacturing, acquisition and analysis are not needed, the complication of manual operation is avoided, the time for judging the RULA score of the test posture is greatly reduced, the subjectivity of manual judgment is avoided, the accuracy of RULA score judgment is greatly improved, and the quick, real-time and accurate evaluation of the human-machine work efficiency of the RULA model is carried out.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic flow chart of a method provided by an embodiment of the present invention;
FIG. 2 is a schematic major sagittal plane view provided by an embodiment of the present invention;
FIG. 3 is a schematic view of a first modified sagittal plane according to an embodiment of the present invention;
FIG. 4 is a schematic view of a second modified sagittal plane provided by an embodiment of the present invention;
FIG. 5 is a schematic view of a third modified sagittal plane provided by embodiments of the present invention;
FIG. 6 is a chart of upper arm, forearm and wrist correction score evaluation according to an embodiment of the present invention;
FIG. 7 is a diagram illustrating the evaluation of the modified scores of the neck and torso according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to solve the problems that the rapid, real-time and accurate evaluation of the human-computer work efficiency of the RULA model cannot be realized in the prior art, the invention provides the following scheme:
as shown in fig. 1, the present invention provides a real-time RULA evaluation method in virtual reality, including:
acquiring an action frame, establishing a space coordinate system based on the action frame, extracting joint point coordinates based on the space coordinate system, and acquiring each limb vector based on the joint point coordinates;
the Vive HMD, the Kinect v2 and the Leapmotion are used as human body motion capture equipment, each motion frame is collected in the test process, joint point positions of a test person in the motion frames are collected, a space coordinate system is established for describing position relation and calculating conveniently, and joint point coordinates corresponding to the joint points are collected in the space coordinate system based on the joint point positions.
The joint points comprise caudal vertebra, neck, head, left shoulder, left elbow, left wrist, left hand, right shoulder, right elbow, right wrist, right hand, left hip, right hip and shoulder vertebra, and the corresponding joint point coordinates comprise caudal vertebra j0Neck j2And a head j3Left shoulder j4Left elbow j5And the left wrist j6Left hand j7Right shoulder j8Right elbow j9And a right wrist j10And the right hand j11Left hip j12Right hip j16And the shoulder vertebra j20。
The limb vectors include a torso vector vtruckThe neck vector vneckRight upper arm vector vruaUpper left arm vector vluaRight front arm vector vrlaLeft forearm vector vllaRight wrist vector vrwAnd left wrist vector vlw。
The coordinate relationship between the limb vector and the joint point is shown in the following table 1:
TABLE 1
Figure BDA0003092782500000061
Acquiring a main sagittal plane and a correction sagittal plane based on the joint point coordinates and the coordinate axis in the space coordinate system:
as shown in fig. 2, a main sagittal plane is obtained based on the shoulder, left and right shoulder coordinates, wherein the shoulder coordinate j20Located in the main sagittal plane, from the left shoulder coordinate j4Point to the right shoulder coordinate j8Is shoulder vector vrs-ls，vrs-ls＝j4-j8Shoulder vector vrs-lsIs the normal vector of the major sagittal plane.
3-5, the modified sagittal planes include a first modified sagittal plane, a second modified sagittal plane, and a third modified sagittal plane; the first correction sagittal plane is used for calculating a body torsion correction score and a neck torsion correction score based on each limb vector; the second correction sagittal plane is used for calculating a lateral bending correction score of the trunk based on each limb vector; and the third correction sagittal plane is used for calculating a neck lateral bending correction score, an upper arm lateral bending correction score and a forearm lateral bending correction score based on the limb vectors. Wherein,
and acquiring the first modified sagittal plane based on an x axis and a y axis in the space coordinate system, wherein the x axis and the y axis in the space coordinate system are positioned on the first modified sagittal plane.
And acquiring the second correction sagittal plane based on the left hip coordinate, the right hip coordinate and the coordinate axis in the space coordinate system, wherein the left hip coordinate and the right hip coordinate are positioned on the second correction sagittal plane, and the y axis in the space coordinate system is parallel to the second correction sagittal plane.
And acquiring the third correction sagittal plane based on the trunk vector, the left shoulder coordinate and the right shoulder coordinate, wherein the trunk vector is positioned on the third correction sagittal plane, and a vector pointing to the right shoulder coordinate from the left shoulder coordinate and a vector cross-multiplied by the trunk vector are normal vectors of the third correction sagittal plane.
Then projecting each limb vector to the main sagittal plane to obtain a main projection vector of each limb vector, and obtaining each limb main angle of each limb vector on the main sagittal plane according to the main projection vector; acquiring main scores of all limbs based on the main angles of all limbs;
the specific steps for obtaining the main score of each limb comprise:
calculating projection vectors of all the limb vectors on a normal vector of the main sagittal plane, calculating main projection vectors of all the limb vectors on the main sagittal plane through the projection vectors, then calculating included angles among the main projection vectors of all the limb vectors to obtain main angles of all the limb vectors, and matching corresponding scores of the main angles in an RULA working table to obtain main scores of all the limbs.
Torso vector vtruckUnit normal vector n in sagittal plane SrlProjection vector in direction is vrl-truckWherein v isrl-truck＝nrl·vtruck·nrl
Further, the torso vector vtruckThe projection vector in the sagittal plane S is v'truckWherein v'truck＝vtruck-nrl·vtruck·nrl
The calculation method of the main projection vectors of the other limb vectors on the main sagittal plane is the same as that of the trunk vector, namely the neck vector vneckRight upper arm vector vruaUpper left arm vector vluaRight front arm vector vluaLeft forearm vector vllaA principal projection vector in a principal sagittal plane S is v'truck、v'rua、v'lua、v'rla、v'lla，
Wherein:
v'neck＝vneck-nrl·vneck·nrl v'rua＝vrua-nrl·vrua·nrl v'lua＝vlua-nrl·vlua·nrlv'rla＝vrla-nrl·vrla·nrl v'lla＝vlla-nrl·vlla·nrl。
calculating the principal score of the trunk, the vector v of the trunktruckProjection vector v 'on sagittal plane S'truckWith the y-axis n of the world coordinate systemyThe included angle between the two is the main body angle thetatruckWherein
Figure BDA0003092782500000081
And judging the main angle of the trunk through the RULA worksheet to obtain a main score of the trunk.
Calculating a neck principal score, the curvature of the neck being relative to the torso, so calculating a neck principal projection vector v'neckAnd torso principal projection vector v'truckThe included angle between the two is the main angle theta of the neckneckWherein
Figure BDA0003092782500000082
the neck posture characteristics are divided into forward tilting and backward tilting, so that whether the neck is forward tilting or backward tilting is judged firstly, and the neck main projection vector v'neckVector H vertical on main sagittal plane and with vector direction as orientation of test facezAnd torso vector vtruckThe included angle between is thetaneckjudgeWherein
Figure BDA0003092782500000091
if it is
Figure BDA0003092782500000092
The neck part tilts forward; if it is
Figure BDA0003092782500000093
The neck is tilted backwards.
And judging the main angle of the trunk through the RULA worksheet to obtain the main neck score. If the neck leans backwards, the primary score of the neck is 4; if the neck is inclined forward, the angle theta of the neck is determinedneckTo obtain a corresponding neck primary score S'neck。
Calculating main score S 'of upper arm'upperarmThe anteversion or retroversion of the upper arm is relative to the torso, and therefore, the upper arm vector vupperarmProjection vector v 'in sagittal plane S'upperarmVector v with torsotruckProjection vector v 'in sagittal plane S'truckThe included angle between the two is the front or rear inclination angle theta of the upper armupperarm。
The upper arm is divided into a left upper arm and a right upper arm, and the upper arm main score is the larger value of the left upper arm score and the right upper arm score. Upper left arm vector vluaPrimary projection vector v 'in sagittal plane S'luaAnd vector v'truckThe included angle between the left and the upper arm is the main angle thetaluaWherein
Figure BDA0003092782500000094
the main angle theta of the right upper arm can be obtained in the same wayrua
Figure BDA0003092782500000095
The calculation of the upper arm principal score is discussed in terms of anteversion and retroversion, but when θ is equalluaOr thetaruaAbove 45, the difference in scores will occur between the anteversion and retroversion of the upper arm.
The virtual human body orientation is a vector obtained by cross multiplication of a trunk vector and a shoulder vector. Left shoulder j4To the right shoulder j8Vector v ofls-rsIs v isls-rs＝j8-j4Virtual human body orientation is vbdWherein v isbd＝vtruck×vls-rs
Calculating virtual human body orientation vbdAnd upper arm vector vupperarmVector v with torsotruckSum vuat(vuat＝vupperarm+vtruck) Angle theta therebetweenupperarmjudgeMake a judgment of thetaupperarmjudgeAs shown in the following formula.
Figure BDA0003092782500000101
If it is
Figure BDA0003092782500000102
The upper arm tilts backwards; if it is
Figure BDA0003092782500000103
The upper arm leans forward.
Aiming at main angle theta of upper arm through RULA working tableupperarmJudging to obtain an upper arm primary score S'upperarm。
Main angle theta of left forearmllaAnd right front arm main angle thetarlaAnd forearm primary score S'lowerarmComputing
Anteversion of the forearm is relative to the torso, so the forearm angle θlowerarmFor the forearm vector vlowerarmProjection vector v 'in sagittal plane S'lowerarmVector v with torsotruckProjection vector v 'in sagittal plane S'truckThe included angle therebetween.
The forearm is divided into a left forearm and a right forearm, and the forearm score is the greater of the left forearm principal score and the right forearm principal score.
Left forearm vector vllaProjection vector v 'in sagittal plane S'llaAnd vector v'truckAngle theta therebetweenllaWherein:
Figure BDA0003092782500000104
the main angle theta of the right front arm can be obtained in the same wayrla，
Figure BDA0003092782500000105
Alignment of forearm principal angle theta by RULA worksheetlowerarmJudging to obtain a main forearm score S'lowerarm。
Principal angle of left wrist thetalwAnd a right wrist principal angle thetarwAnd the wrist is dominantScore of S'wristComputing
The wrist is bent relative to the forearm, so the wrist angle θwristAs a vector v of the wristwristVector v with forearmlowerarmThe included angle therebetween.
The wrists are divided into a left wrist and a right wrist, and the dominant wrist score is the larger value of the dominant left wrist score and the dominant right wrist score.
Left wrist vector vlwAnd the left forearm vector vllaThe included angle between is thetaleftwristWherein
Figure BDA0003092782500000111
the main angle theta of the right wrist can be obtained by the same methodrwWherein:
Figure BDA0003092782500000112
main angle theta of wrist by RULA working tablewristJudging to obtain a primary wrist score S'wrist。
Projecting each limb vector to the correction sagittal plane to obtain the correction projection vector of each limb vector, and obtaining the correction angle of the limb vector on the correction sagittal plane according to the correction projection vector; obtaining correction scores of all limbs based on the correction angles;
the specific steps of obtaining the correction angle of the limb vector on the correction sagittal plane comprise: and acquiring the posture factor under the current correction angle based on the correction angle, and obtaining the correction score of each limb by matching the corresponding correction score of the posture factor in the RULA worksheet as shown in FIGS. 6-7.
Torso twist correction score calculation.
According to the RULA worksheet, the torso modification score is determined by two factors, whether the torso is twisted and whether the torso is bent sideways. If the trunk is twisted but not bent sideways, or if the trunk is bent sideways but not twisted, the score S is corrected for the trunk "truckIs 1 minute; if the trunk twists and turns sideways, the score S is corrected for the trunk "truckIs divided into 2 parts; if the trunk is not twistedAlso without lateral bending, trunk correction score S "truckIs 0 min.
Wherein, the sagittal plane SxozProjection sagittal plane calculated for trunk torsion, and normal vector thereof is y-axis n of world coordinate systemy(ii) a Shoulder vector vls-rsIs a left shoulder j4Finger to right shoulder j8Vector of (i), i.e. vls-rs＝j8-j4(ii) a Hip vector vlh-rhIs a left hip j12Point to the right hip j16Vector of (i), i.e. vlh-rh＝j16-j12. If the trunk twists, the shoulder vector vls-rsIn the sagittal plane SxozUpper projection vector v "ls-rsAnd hip vector vlh-rhIn the sagittal plane SxozUpper projection vector v "lh-rhNon-parallel, with an included angle thetatrucktwist(torso twist correction angle).
Shoulder vector vls-rsHip vector vlh-rhIn the first modified sagittal plane SxozThe projection vector on is v "ls-rs、v”lh-rhWherein: v'ls-rs＝vls-rs-ny·vls-rs·ny，v”lh-rh＝vlh-rh-ny·vlh-rh·ny
So that the trunk twist correction angle thetatrucktwist：
Figure BDA0003092782500000121
To thetatrucktwistIf the threshold value is set to 20 DEG, then
Figure BDA0003092782500000122
Trunk torsion is considered; if it is
Figure BDA0003092782500000123
The trunk is considered to be untwisted.
Scoliosis calculation, wherein the second correction plane is sagittal Sh-yProjected sagittal plane calculated for lateral curvature of torso, second modified sagittal plane Sh-yHas a unit normal vector of
Figure BDA0003092782500000124
If the trunk is bent sideways, the trunk vector vtruckIn the second modified sagittal plane Sh-yIs projected vector v "truckWith the y-axis n of the world coordinate systemyBetween them forms an included angle thetatruckbend(torso lateral bending correction angle) is not zero.
Torso vector vtruckIn the sagittal plane Sh-yIs projected vector v "truckAs shown in the following formula:
Figure BDA0003092782500000125
so that the trunk twist correction angle thetatruckbendAs shown in the following formula:
Figure BDA0003092782500000131
to thetatruckbendIf the threshold value is set to 20 DEG, then
Figure BDA0003092782500000132
The torso is considered to be lateral; if it is
Figure BDA0003092782500000133
The torso was considered not to be bent sideways.
Calculation of neck correction score:
according to the RULA worksheet, the neck correction score is determined by two factors, i.e., whether the neck is twisted and whether the neck is bent sideways. If the neck is twisted but not bent sideways, or if the neck is bent sideways but not twisted, the neck correction score S "neckIs 1 minute; if the neck is twisted and the neck is bent sideways, the score S is corrected for the neck "neckIs divided into 2 parts; if the neck is not twisted or bent, the score S is corrected "neckIs 0 min.
Neck torsion determination
Neck torsion calculation: wherein the first modified sagittal plane SxozThe projected sagittal plane is calculated for the cervical torsion. Neck main projection vector v'neckVector H vertical to main sagittal plane and oriented in vector direction of test personzAnd a virtual human body orientation vector vbdRespectively to the first modified sagittal plane SxozProjecting to obtain vector H "zSum vector v "bdIf the neck is twisted, vector H "zSum vector v "bdNon-parallel, with an included angle thetanecktwist(cervical twist correction angle).
Vector HzIn the sagittal plane SxozUpper projection vector H'zWherein: h'z＝Hz-ny·Hz·ny
vbdIn the sagittal plane SxozUpper projection vector v "bd，v”bd＝vbd-ny·vbd·ny
So that the neck portion torsion judging angle thetanecktwistAs shown in the following formula.
Figure BDA0003092782500000134
To thetanecktwistIf the threshold value is set to 20 DEG, then
Figure BDA0003092782500000135
Consider the neck twisted; if it is
Figure BDA0003092782500000136
The neck is considered untwisted.
Neck lateral bending calculation
Wherein the third modified sagittal plane Str-bdIs a projection sagittal plane calculated by the lateral bending of the neck, and the normal vector of the projection sagittal plane is the virtual human body orientation vbd. Neck lateral bending correction angle thetaneckbendIs a neck vector vneckIn the sagittal plane Str-bdUpper projection vector v "neckVector v with torsotruckThe included angle therebetween.
Neck vector vneckIn the sagittal plane Str-bdUpper projection vector v "neckWherein:
Figure BDA0003092782500000141
so that the neck side bend judges the angle thetaneckbendAs shown in the following formula.
Figure BDA0003092782500000142
To thetaneckbendIf the threshold value is set to 20 DEG, then
Figure BDA0003092782500000143
Consider the neck to be bent sideways; if it is
Figure BDA0003092782500000144
The neck was considered not to be bent sideways.
Upper arm correction score
According to the RULA worksheet, the upper arm correction score is determined by two factors, namely whether the shoulder is lifted up and whether the upper arm is abducted. If the shoulder is lifted but the upper arm is not abducted, or the upper arm is abducted but the shoulder is not lifted, the upper arm corrects the score S "upperarmIs 1 minute; if the upper arm abducts and the shoulder is lifted, the upper arm corrects the score S "upperarmIs divided into 2 parts; if the upper arm is not abducted and the shoulder is not lifted, the upper arm corrects the score S "upperarmIs 0 min.
Shoulder lifting calculation
The shoulder lifting is divided into right shoulder lifting and left shoulder lifting. If the right shoulder is lifted upwards, the right shoulder vector vrsIn the third modified sagittal plane Str-bdIs projected vector v "rsVector v with torsotruckAngle theta therebetweenrs-upp(right shoulder up judgment angle) is less than 90 °. Similarly, if the left shoulder is lifted, the left shoulder is in the sagittal plane Str-bdIs projected vector v "lsVector v with torsotruckBetweenAngle of (theta)ls-upp(left shoulder up judgment angle) is less than 90 °. Wherein, the right shoulder vector vrsIs v isrs＝j8-j20(ii) a Left shoulder vector vlsIs v isls＝j4-j20。
Left shoulder vector vlsIn the sagittal plane Str-bdIs projected vector v "lsAs shown in the following formula.
Figure BDA0003092782500000151
So that the left shoulder is lifted up by the judgment angle thetals-uppAs shown in the following formula.
Figure BDA0003092782500000152
The right shoulder lifting judgment angle theta can be obtained by the same methodrs-uppThe following formula is shown below.
Figure BDA0003092782500000153
Setting the threshold value to 20 °, if it occurs
Figure BDA0003092782500000154
Or
Figure BDA0003092782500000155
Adding 1 point to the upper arm correction score, otherwise not correcting the upper arm score.
Upper arm abduction calculation
The upper arm abduction is divided into right upper arm abduction and left upper arm abduction. If the right upper arm abducts, the vector v of the right upper armruaIn the sagittal plane Str-bdIs projected vector v "ruaVector v with torsotruckNon-parallel, with an included angle thetarua-ex(right upper arm abduction judgment angle). Similarly, if the left upper arm is abducted, the left upper arm is in the sagittal plane Str-bdIs projected vector v "luaVector to trunkvtruckNon-parallel, with an included angle thetalua-ex(angle of judgment of abduction of left upper arm).
Upper right arm vector vruaIn the third modified sagittal plane Str-bdIs projected vector v "ruaAs shown in the following formula.
Figure BDA0003092782500000156
The abduction of the right upper arm is judged by the angle thetarua-exAs shown in the following formula.
Figure BDA0003092782500000161
The same reason can be obtained for judging the abduction angle theta of the left upper armlua-exThe following formula is shown below.
Figure BDA0003092782500000162
Setting the threshold value to 20 deg., if it appears
Figure BDA0003092782500000163
Or
Figure BDA0003092782500000164
The upper arm correction score is increased by 1 point.
Forearm correction score
According to the RULA worksheet, the forearm correction score is determined by whether the forearm is placed on the other side of the body midline, or whether the forearm is placed on the outside of the body. If the forearm is placed on the other side of the body midline or on the outside of the body, the forearm is assigned a revised score S "lowerarmIs 1 minute; otherwise forearm correction score S "lowerarmIs 0 min.
Calculation of forearm to outside body
Third modified sagittal plane Str-bdIs the projected sagittal plane calculated with the forearm placed outside the body. The front arm is arranged on the outer side of the body and is divided into a right front armPlaced on the outside of the body and the left forearm on the outside of the body. If the right forearm is placed outside the body, the right forearm vector vrlaIn the third modified sagittal plane Str-bdIs projected vector v "rlaVector v with torsotruckNon-parallel, angle of thetarla-ex(the right forearm is placed outside the body to judge the angle). Similarly, if the left forearm is placed on the outside of the body, the left forearm vector vllaIn the sagittal plane Str-bdIs projected vector v "llaVector v with torsotruckNon-parallel, angle of thetalla-ex(left forearm placed outside body to judge angle).
Vector v of right forearmrlaIn the sagittal plane Str-bdIs projected vector v "rlaAs shown in the following formula.
Figure BDA0003092782500000165
So that the right forearm is placed outside the body to judge the angle thetarla-exAs shown in the following formula.
Figure BDA0003092782500000171
The left forearm placed outside the body can be judged to have the angle theta in the same waylla-exThe following formula is shown below.
Figure BDA0003092782500000172
If the threshold value is set to 20 DEG, then
Figure BDA0003092782500000173
Or
Figure BDA0003092782500000174
The forearm is considered to be placed on the other side of the body, otherwise the forearm is considered to be not placed on the other side of the body.
Calculation of forearm placed on opposite side of body midline
If the left forearm is placed on the other side of the body midline, vector vrs-lwIn the vector vrs-ssUpper projection vector v "rs-lwHas a modular length smaller than the vector vrs-ssDie length of (v) "rs-lwI (left forearm placed on the other side of body midline determines modular length), i.e. | v "rs-lw|＜|vrs-ssL. Wherein v isrs-lwIs a right shoulder j8To the left wrist j6Vector of (i), i.e. vrs-lw＝j6-j8(ii) a Is v isrs-ssRight shoulder j8To shoulder vertebra j20Vector of (i), i.e. vrs-ss＝j20-j8。
So that the left forearm is placed on the other side of the midline of the body to determine the length of the model | v "rs-lwThe formula is shown below.
Figure BDA0003092782500000175
In the same way, the right front arm is placed on the other side of the midline of the body to judge the model length | v "ls-rwAnd is shown in the following formula.
Figure BDA0003092782500000176
Therefore, if | v "rs-lw|＜|vrs-ssI, or i v "ls-rw|＜|vls-ssIf not, the forearm is not placed on the other side of the body midline.
And obtaining total scores of all the limbs based on the main scores of all the limbs and the corrected scores of all the limbs, and performing score matching through an RULA worksheet based on the total scores of all the limbs to obtain the RULA scores of the human postures.
Through the process, the trunk main score S 'is obtained'truckPrimary neck score S'neckAnd main score S 'of upper arm'upperarmMain score of forearm S'lowerarmWrist main score S'wrist(ii) a Obtaining the trunk correction score S by a correction score criterion calculation formula "truckNeck correction partValue S'neckUpper arm correction score S "upperarmForearm correction score S "lowerarm. Wrist score SwristAnd wrist primary score S'wristSame torso score StruckNeck score SneckUpper arm score SupperarmForearm score SlowerarmNeeds to be corrected, which is the sum of the main score of each limb of the human body and the corresponding correction score, as shown in the following formula.
Struck＝S'truck+S”truck
Sneck＝S'neck+S”neck
Supperarm＝S'upperarm+S”upperarm
Slowerarm＝S'lowerarm+S”lowerarm
Through the above calculation, the main score and the corrected score of each limb RULA are determined from fig. 6 and 7, then the total score of each limb RULA is obtained by the above formula calculation, the a table and the B table in the RULA working table are searched, then muscle assessment is carried out, namely, under the condition that the limb RULA is kept still for longer than one minute or the posture is repeated for more than four times within one minute, the total score is added with 1, and force and load assessment is carried out, namely, no resistance or intermittent load less than 2kg or total score of resistance is unchanged, the total score of static load or periodic load of 2-10kg or total score of resistance is added with 1, the total score of static load or periodic load of 2-10kg is added with 2, the total score of static coincidence, repetitive load or impact, and transient load greater than 10kg is added with 3, the C component value and the D component value are obtained based on the above assessment, and finally the C table is searched to obtain the RULA score. The posture was rated in four grades based on the RULA score obtained from table C:
(1)1-2 points of: it is acceptable that the posture is not maintained, or repeated for a long time.
(2)3-4 min: the posture needs to be studied and changed after a long time.
(3)5-6 min: after a period of time, the posture needs to be studied and changed.
(4)7, dividing: the posture needs to be studied and changed immediately.
Wherein, the A table, the B table and the C table are shown in the tables 2, 3 and 4,
TABLE 2
Figure BDA0003092782500000191
TABLE 3
Figure BDA0003092782500000192
Figure BDA0003092782500000201
TABLE 4
Figure BDA0003092782500000202
Compared with the prior art, the invention has the following effects:
according to the method, the main sagittal plane is constructed, the sagittal plane is corrected, the limb vectors are projected to each sagittal plane, then the angle calculation of the projection vectors is carried out, and the score judgment is carried out by combining with the RULA worksheet, so that the RULA score of the test posture can be obtained, the manual analysis is not needed, the complexity of the manual judgment is avoided, the time for judging the RULA score of the test posture is greatly reduced, the subjectivity of the manual judgment is avoided, the accuracy of the RULA score judgment is greatly improved, and the quick, real-time and accurate evaluation of the human-computer work efficiency of the RULA model is carried out.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (10)

1. A real-time RULA evaluation method in virtual reality is characterized by comprising the following steps:
acquiring an action frame, establishing a space coordinate system based on the action frame, extracting joint point coordinates based on the space coordinate system, and acquiring each limb vector based on the joint point coordinates;
acquiring a main sagittal plane and a correction sagittal plane based on the joint point coordinates and the coordinate axis in the space coordinate system;
projecting each limb vector to the main sagittal plane to obtain a main projection vector of each limb vector, and obtaining each limb main angle of each limb vector on the main sagittal plane according to the main projection vector; acquiring main scores of all limbs based on the main angles of all limbs;
projecting each limb vector to the correction sagittal plane to obtain the correction projection vector of each limb vector, and obtaining the correction angle of the limb vector on the correction sagittal plane according to the correction projection vector; obtaining correction scores of all limbs based on the correction angles;
and obtaining total scores of all the limbs based on the main scores of all the limbs and the corrected scores of all the limbs, and obtaining the RULA scores of the human body postures through the RULA worksheet based on the total scores of all the limbs.
2. The real-time RULA evaluation method in virtual reality according to claim 1, wherein:
the joint point coordinates comprise caudal vertebra coordinates, neck coordinates, head coordinates, left shoulder coordinates, right shoulder coordinates, left elbow coordinates, right elbow coordinates, left wrist coordinates, right wrist coordinates, left hand coordinates, right hand coordinates, left hip coordinates, right hip coordinates and shoulder vertebra coordinates.
3. The real-time RULA evaluation method in virtual reality according to claim 2, wherein:
each limb vector comprises a body vector, a neck vector, a right upper arm vector, a left upper arm vector, a right front arm vector, a left front arm vector, a right wrist vector and a left wrist vector.
4. The real-time RULA evaluation method in virtual reality according to claim 2, wherein:
the specific steps for obtaining the main sagittal plane include:
and acquiring a main sagittal plane based on a shoulder vertebra coordinate, a left shoulder coordinate and a right shoulder coordinate, wherein the shoulder vertebra coordinate is positioned on the main sagittal plane, and a vector pointing to the right shoulder coordinate from the left shoulder coordinate is a normal vector of the main sagittal plane.
5. The real-time RULA evaluation method in virtual reality according to claim 3, wherein:
the modified sagittal planes comprise a first modified sagittal plane, a second modified sagittal plane and a third modified sagittal plane;
the first correction sagittal plane is used for calculating a body torsion correction score and a neck torsion correction score based on each limb vector;
the second correction sagittal plane is used for calculating a lateral bending correction score of the trunk based on each limb vector;
and the third correction sagittal plane is used for calculating a neck lateral bending correction score, an upper arm lateral bending correction score and a forearm lateral bending correction score based on the limb vectors.
6. The real-time RULA evaluation method in virtual reality according to claim 5, wherein:
the specific step of obtaining the first modified sagittal plane includes:
and acquiring the first modified sagittal plane based on an x axis and a y axis in the space coordinate system, wherein the x axis and the y axis in the space coordinate system are positioned on the first modified sagittal plane.
7. The real-time RULA evaluation method in virtual reality according to claim 5, wherein:
the specific step of obtaining the second modified sagittal plane includes:
and acquiring the second correction sagittal plane based on the left hip coordinate, the right hip coordinate and the coordinate axis in the space coordinate system, wherein the left hip coordinate and the right hip coordinate are positioned on the second correction sagittal plane, and the y axis in the space coordinate system is parallel to the second correction sagittal plane.
8. The real-time RULA evaluation method in virtual reality according to claim 5, wherein:
the specific step of obtaining the third modified sagittal plane includes:
and acquiring the third correction sagittal plane based on the trunk vector, the left shoulder coordinate and the right shoulder coordinate, wherein the trunk vector is positioned on the third correction sagittal plane, and a vector pointing to the right shoulder coordinate from the left shoulder coordinate and a vector cross-multiplied by the trunk vector are normal vectors of the third correction sagittal plane.
9. The real-time RULA evaluation method in virtual reality according to claim 1, wherein:
the specific steps for obtaining the main score of each limb comprise:
calculating projection vectors of all the limb vectors on a normal vector of the main sagittal plane, calculating main projection vectors of all the limb vectors on the main sagittal plane through the projection vectors, then calculating included angles among the main projection vectors of all the limb vectors to obtain main angles of all the limb vectors, and matching corresponding scores of the main angles in an RULA working table to obtain main scores of all the limbs.
10. The real-time RULA evaluation method in virtual reality according to claim 1, wherein:
the specific steps of obtaining the correction score of each limb based on the correction angle are as follows:
and acquiring the posture factors under the current correction angle based on the correction angle, and obtaining the correction score of each limb by matching the corresponding correction score of the posture factors in the RULA working table.
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