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D. Chablat - January 2016 2
Simulation activities?
• Simulation of assembly and disassembly – Check if a part or assembly can be assembled / disassembled in its environment. – The trajectory simulation is performed by a design engineer and / or a maintenance
actor. • Maintenance Simulation
– Check if a part or assembly can be mounted / dismounted by an operator or a manufacturing system (tools, robots ...).
– Trajectory, order handling, validation by experts maintenance. • Human Simulation / definition and validation process
– Simulate a part or assembly can be mounted / dismounted by an operator or a manufacturing system.
– Perform simulation of an operator / a manufacturing process defined by a maintenance / manufacturing expert.
D. Chablat - January 2016 3
Simulation activities?
• Study workstations to reduce musculoskeletal disorders (MSDs).
D. Chablat - January 2016 4
Ergonomics and musculoskeletal disease
• Distribution by member
D. Chablat - January 2016 5
Musculoskeletal disorders: definition (INRS)
• "[...] MSDs are multifactorial diseases with professional component. The stresses that are causing MSDs are biomechanical, organizational and psychosocial.
• MSDs affect primarily the muscles, tendons and nerves, that is to say soft tissue. In muscle, the main constraint is force. This stress can lead to muscle fatigue. Tendons, major mechanical stresses are exerted tensile forces developed by the muscle during muscular effort as well as friction and compression against adjacent tissues. This can result in inflammation of the tendon (tendinitis) or tendon and its sheath (tenosynovitis). For nerves, compression is the main mechanical stress. The most common pathology is carpal tunnel syndrome.
• Clinical symptoms of MSDs is poor and the pain is often the only sign. [...] "
D. Chablat - January 2016 6
Cost of the MSD
• In 2009 – 8.3 million workdays – 875 million euros compensation
• Example – Carpal tunnel syndrome: 11,000 euros in direct costs – “stiffen” shoulder 80,000 euros of direct costs – Indirect cost .... 2 to 3 times more!
D. Chablat - January 2016 7
Learning outcomes
• Having notions about anthropometry • Transfer to simulation software • Have notions on dynamic anthropometry • Definition efforts • Definition task • Travel and labor utilization • Ergonomic analysis
D. Chablat - January 2016 8
Human / Anthropometry
• The "Human Machine": – The average man does not exist – Extreme variability of characteristics of an individual to another:
• Shape, dimensions • Resistance tolerance • Functional capacities (perceptual, cognitive, motor ...) => always consider a
target population – Changing characteristics over time (age, aging)
D. Chablat - January 2016 9
Definitions
• Anthropometry : – "Anthropos" man; "Metron" measure. – Study and measurement of the physical dimensions of the human body. – Typically there are:
• static anthropometry • dynamic anthropometry
• Biomechanics: – Approach to the structure and functioning of living beings based on the
laws of mechanics.
D. Chablat - January 2016 10
Definitions
• Standards to define the man behavior: – "Documents prepared by consensus, which provide for common and
repeated use, rules, guidelines or characteristics for activities or their results, aimed at optimal level of order in a given context“
– Designed of all the information provided by anthropometry and biomechanics.
– These standards do not cover all individuals but serve as a reference document.
– They are essentially indicative. – Available from the regional delegation of the AFNOR (French Association
for Standardization).
D. Chablat - January 2016 11
Main goals
• Know the dimensions: – Operators for the design of workstations
• Study of the mutual relations between the measurements of the human body and the dimensions of the workplace, machines and the physical environment.
– Users for product design • Renault (REBIFFE et al.) 1981-1982 • Measurement campaign for the clothing industry in 2006
D. Chablat - January 2016 12
Statistical concepts
• Impossible to generalize to a large number of individuals the measurements made on a single
• Knowledge of the average of insufficient sample: need to know the variation of the dimensions among the population for the design of tools or workstation used by the majority of people
D. Chablat - January 2016 13
Statistical concepts
D. Chablat - January 2016 14
Statistical concepts
• Calibration percentile (or percentiles): cutting the percentage workforce.
• Between the 5th and 95th percentile are considered for the character including 90% of the subjects dealt with.
• These concepts are taken into account by standardization. • Example: EN 614-1:
– When designing a working equipment to be adapted to a population of operators to use percentiles must go at least the 95th percentile on the 5th.
– When health and safety are important factors should be used wider beaches, normally the 99th and / or the 1st percentile.
D. Chablat - January 2016 15
Variability
D. Chablat - January 2016 16
Variability
5% de la population dans
cette zone
5% de la population dans
cette zone
90% de la population dans
cette zone
Variable mesurée
Fréquence
5ème centile 50ème centile 95ème centile
D. Chablat - January 2016 17
Usage of statistical data
• The average and dispersion of the population must be taken into account.
• The increase in the amplitude adjustment enables the increase in population satisfied, but this gain is increasingly expensive to obtain as one moves away from the average.
D. Chablat - January 2016 18
Static anthropometry
• Measurement of body segments of individuals • Goal :
– obtain an anthropometric profile
• Methodology : – Data collection using specific equipment (stool, height gauge, protractor ...)
under standardized measurement conditions. – Interpretation of data (correlation matrix, AFNOR).
D. Chablat - January 2016 19
Measurement of the size
• Height = height = body stature • The more practiced, easier to use • Useful: good correlation with measures such useful length design • Method for height of Martin:
– The vertical distance between the top of the head (vertex) and the ground
– Topic standing straightened up, feet – Position defined by EN ISO 7250
D. Chablat - January 2016 20
Size: mean and dispersion
D. Chablat - January 2016 21
Measurement of the size / weight
• Variability factors: – Posture – Time of Day – Growth / senescence – Sex – Genetics and lifestyle
• Statistics in France (2000) – Man: average 175 cm (10 cm in 1 century) 76 Kg – Women: average 162 cm (7 cm in 1 century) 63 Kg
D. Chablat - January 2016 22
Measurement of the size
D. Chablat - January 2016 23
Measurement of the size
D. Chablat - January 2016 24
Segmental dimensions
• All measures must be carried out with the same method for all measurements
• The measurement conditions are specified by the ISO 7250 standard
• Calculation of inter-articular distances: – Calculated by applying the different measures segmental a corresponding
coefficient. – Example: distance shoulder joint / articulation elbow = 80% of the elbow
shoulder measured distance.
D. Chablat - January 2016 25
Segmental dimensions
D. Chablat - January 2016 26
Segmental dimensions
D. Chablat - January 2016 27
Population and modeling of the human
• How to evaluate a population? – The anthropometry is the technique for the measurement of dimensional characteristics of a man. – It is particularly used in ergonomics.
• For man, it concerns including: – The dimensions
• Stature (commonly known size) • The height of the bust • The length of each member and each member part (arms, forearms)
– The masses • Total weight • Mass of each body part • The centers of gravities
– Circumferences, sometimes called crowns • Pelvis, chest, neck ... • Circumference members
D. Chablat - January 2016 28
Population and modeling of the human
• Which databases? – European populations, American, Japanese – Multiple database standards (ISO 15535 and ISO 7250) – Several model digital mannequin (as H-Anim)
• Problems links between databases and? • Their representation ... number of parameters? • Different (45) • Mainly military databases US? (Not very recent
or representative? Of the population).
D. Chablat - January 2016 29
Population and modeling of the human
• Links between height and weight and its members
Segment LongueurBras 0.186HAvan t bras 0.146HMain 0.108HCuisse 0.245HJambe 0.246HPied 0.039H
Groupe de segment par rapport Segment au % de la masse totale % du poids Tête et cou=8.4% Tête=73.8% Cou=26.2% Torse=50% Thorax=43.8% Lumbaire=29.4% Bassin=26.8% Total bras=5.1% Bras=54.9% avant-bras =33.3% Main=11.8% Total jambe=15.7% Cuisse=63.7% Jambe=27.4% Pied=8.9%
But, these are only averages ...
D. Chablat - January 2016 30
Human modeling
• One of the representations of the virtual human is dictated by robotic techniques for animation.
• The virtual human is assimilated to a tree poly-articulated structure of solids, we call naturally enough skeleton.
• A geometry in relation to the topology of the human body, is attached to the solid or bone.
• Two bones are separated by a joint. • This representation is quite "rigid" and differs somewhat
from the idea that we have of a real human.
D. Chablat - January 2016 31
Human modeling
• The skeleton - a complex mechanism – The human skeleton consists of 206 bones. – The skeleton allows us to keep us right, that's our
frame. Without him we would have to crawl like worms.
– Most bones are interconnected by joints. – In some cases, there is no joint as in the skull which
is composed of 8 flat bones and the face 14 of which only the bone jaw is hinged.
– The longest bone is the femur, the thigh bone. The smallest is one of the small bones of the inner ear.
D. Chablat - January 2016 32
Human modeling
• Examples
D. Chablat - January 2016 33
Human modeling
• (http://ai.stanford.edu/~latombe/cs99k/2000/)
Autonomy
interactivity
User controlled
totally autonomous
Off line Real times
Keyframe animation
systems
Opponents video game
Web Avatars
digital player
Semi-autonomous characters
Urban/ factory Simulation
Virtual tour guides
historical accounts
D. Chablat - January 2016 34
Human modeling in product design
• The main software – DIVISION SW (PTC),
• With the Safework’s mannequin, 148 degrees of freedom, (http://www.safework.com/),
– eMPowers (Tecnomatix/SIEMENS), • With the AnyMan’s mannequin, 60 degrees of freedom, • With the RAMSIS’s mannequin, 104 degrees of freedom
(http://www.human-solutions.com) – Delmia et Catia V5 (Dassault Systèmes)
• With the Safework’s mannequin, 148 degrees of freedom(http://www.safework.com/),
– Jack (EDS), 135 degrees of freedom, (www.ugs.com) – RAMSIS (http://www.human-solutions.com). – VR Com, with the RAMSIS’s mannequin (http://www.vrcom-
online.de), – REAL MAN (http://www.real-man.org/)
D. Chablat - January 2016 35
RAMSIS model
• Virtual human model developed by the German automotive industry
104 degrés de liberté
D. Chablat - January 2016 36
RAMSIS Model
D. Chablat - January 2016 37
Application example with vision
© Delmia
D. Chablat - January 2016 38
Mannequin representation model
• Tree representation • Each body is a tree node • All body markings are local • Two problems to solve
– Direct geometric model • Calculate the posture according to the different joint values. • Good for simulation
– Inverse kinematics • Calculate joint values based on a given position of the hands • Good for control
Root
D. Chablat - January 2016 39
Mannequin implementation in its environment and creating postures
• Features: – Standard library of articulated models. – Posture of creation from a library of
basic postures. – Reachability analysis. – Visual Fields Analysis.
D. Chablat - January 2016 40
Customization mannequin
• Features:
– 104 anthropometric variables – Annotations of these variables – Library management tools
anthropometric – Create a customizable database
operators by population
D. Chablat - January 2016 41
Examine the joint position of posture
• Features: – 148 degrees of freedom – Editor joint limits and comfort limits – Visualization and automatic posture
optimization – Analysis of joint limits and static forces
D. Chablat - January 2016 42
Programmer and then simulate all operations performed by the operator
• Features:
– Walk, – Climb, – Take / drop, – Posture change activity. – Collision checking tool – Using ergonomic tools (anthropometry,
vision damage)
D. Chablat - January 2016 43
Example of path
Reach
Take
Transfert
Drop
Return
D. Chablat - January 2016 44
Example of path
D. Chablat - January 2016 45
Possible uses
• Validation postures – Simulation and static position
evaluation "critical" probable
D. Chablat - January 2016 46
Geometric model
• Forward kinematics – Browse the tree and propagate the kinematic transformations
• Inverse kinematics – Depending on the given position of the end effector,
calculate joint values. – In simple cases, an analytical solution exists. – For a mannequin, there is an infinite number of solutions.
D. Chablat - January 2016 47
Example CATIA
• Use the "Forward kinematics“ • If several link on the joint, use the
context menu
D. Chablat - January 2016 48
Geometric model inverse redundant mechanisms
• A redundant system has infinite solutions – The human skeleton has more than 100 degrees of freedom – It is a hyper redundant system !!! – How to solve a hyper redundant system? – Using the Jacobian pseudo-inverse
• Other methods – Iterative – Taking into account the dynamics
2λ+ −= +T T 1J J (JJ I)
D. Chablat - January 2016 49
Example CATIA
• Use "Inverse Kinematics Worker Frame Mode"
D. Chablat - January 2016 50
Use of standard postures
D. Chablat - January 2016 51
Use of standard postures
D. Chablat - January 2016 52
Use of standard postures
D. Chablat - January 2016 53
Modelling hand
• Kinematic – The hand has 27 bones in the palm of which 8 to 25 joints – For taking object, only part of the joint working
Model "Santos" 25 DOF (http://www.digital-humans.org/hand.htm)
D. Chablat - January 2016 54
Using hand
• Three methods – Manual (Motion Capture) – Automatic (Heuristic) – Semi-automatic
Where grasp an object?
D. Chablat - January 2016 55
Using hand
• Socket object (grasping) – difficult problem – No general algorithm – Examples difficult
• Taking an object by two persons • Object exchange between two people • Indirect manipulation
D. Chablat - January 2016 56
Example CATIA
Page 57
Biomechanical modeling - 3DSSPP
D. Chablat - January 2016
Page 58
Biomechanical modeling - AnyBody
D. Chablat - January 2016
Page 59
Conclusions
anthropométrie
volume accessible
passage des mains
cône de vision
D. Chablat - January 2016
D. Chablat - January 2016 60
Ergonomics
• Definition : – Scientific discipline that aims at understanding the interactions between
people and work, and which finds its application in the design, evaluation and modification of machines and workstations with the aim to adapt them to the physiological and psychological characteristics, capacities and needs of workers.
• Notes: – Ergonomics aims to maximize the efficiency and productivity of workers
and ensure that they operate in a safe work environment and quality. So limit occupational accidents!
– Ergonomics is at the crossroads of several disciplines including psychology, sociology, occupational medicine, physiology and engineering.
D. Chablat - January 2016 61
Dynamic anthropometry
• Working areas of the human – the volume in which it operates – the limits are reached – the gripping areas.
• The dynamic anthropometry can: – the representation of the evolution and maneuvering areas for operators. – determining the preferred location of orders, enter information and warning
signals. – establishing minimum dimensions of passage and work areas.
• Methodology – Graphic construction of an optimal development area of each body segment
materialized by the inter-articular distances taking into account any discomfort angles
– Consideration of angles defining the visual field
D. Chablat - January 2016 62
Angles less discomfort
The comfort of a posture depends on the angles made them the body segments.
• Balance between action of flexor and extensor muscles: the situation is more "comfortable" if the joints are in an intermediate position: no bending or extreme extension.
• Any posture becomes "uncomfortable" if one is not able to change
D. Chablat - January 2016 63
Angles less discomfort
D. Chablat - January 2016 64
Angles less discomfort
D. Chablat - January 2016 65
Angles less discomfort
D. Chablat - January 2016 66
Angles less discomfort
D. Chablat - January 2016 67
Field of view
• Object: – Check the visual accessibility – Monoscopic or stereoscopic vision
D. Chablat - January 2016 68
Recommendations for visual indicators
• Take account of natural sightlines – In the vertical plane, information in an angle of 40 ° below the horizontal
line from the eyes. – In the horizontal plane, important information within an angle of 30 ° in
front of the operator, and accessories within an angle of 60 °. – Ensure that the eye can always control the movements of the hand.
• Facilitate the collection of information – Proper lighting: 300-1000 lux. – Size of the characters. – Good contrast between the object and the background to collect. – Clear identification of areas "normal" and "alert".
D. Chablat - January 2016 69
Limitations of use of the visual field
D. Chablat - January 2016 70
Some limitations of the vertical field
D. Chablat - January 2016 71
Some limitations of the vertical field
D. Chablat - January 2016 72
Extreme reaching areas
• Defined by the spherical portions described by the extended upper limbs (hand catch limit is not exceeded)
• The repeated use of objects at the limit of maximum damage zone requires full extension of the joints and an important local muscle work.
D. Chablat - January 2016 73
Areas affected comfort
• Match the closest areas of the body.
• They are determined by portions of the spheres described by the upper limbs with a forward flexion from 0 ° to 20 °. On a horizontal plane, it is estimated that such areas are limited, in the rotation of the forearm, 40 ° outwards and 60 ° to the body.
• The intersection of the areas left and right comfort determines optimal handling area.
D. Chablat - January 2016 74
Zones of reach of a work plan
D. Chablat - January 2016 75
Zones of reach and passage
• Zones of reach – Favor small (5%): notion of reachability – Consolidate alarms and urgent
intervention in the common areas reached with both hands
• Passage, body stature – focus on large (95%): notion of
accessibility – the set is designed for the largest and
suitable for the smallest.
D. Chablat - January 2016 76
Minimum depth required to work (mm)
D. Chablat - January 2016 77
Measuring muscular forces
• Factors conditioning muscle efficiency: – Position of the joint – Speed of contraction (or movement) – Duration of contraction – Repeatability of movement – Type of effort (static, dynamic) – Considered muscle group – Laterality – Age – Type of population, training, health
• Force (exerted effort): Newton: 1kg # 10N • Energy: force x displacement: Joule: 1N x 1m • Power: power / duration: Watt: 1J / 1s (1 cal = 4.18 J)
D. Chablat - January 2016 78
Measuring muscular forces
• Dynamometer : – Measurement of maximum effort. – Calibrated deformation of a mechanical
device during exercise. – No ability to track the effort over time.
• Extensometer: – Based on the calibrated deformation of
an electrical device during exercise. – Reading by means of a measuring
apparatus and display. – The possibility to monitor the effort
over time.
D. Chablat - January 2016 79
Measuring muscular forces
• Surface Electromyography – Indirect measurement of force by the electrical activity of muscle.
D. Chablat - January 2016 80
Maximum strength of different muscle groups according Tornvall 1963 in Bouisset, S. Maton & B
92 young adults (19-20 years) randomly selected
D. Chablat - January 2016 81
Recommended force limits for the use of machines
• According to the NF EN 1005-3 (2002) (X35-106-3) • Apply to men and women in the general population whose posture
is optimal and circumstances "ideal". • Correspond to the 15th percentile of the total adult population
(men and healthy women from 20 to 65 years).
D. Chablat - January 2016 82
Activité Force (N) Travail avec la main (une main) : Prise pleine main 250
Travail avec le bras (posture assise, un bras) : -Vers le haut -Vers le bas -Vers l’extérieur -Vers l’intérieur -Poussée - sans support du tronc - avec support du tronc -Traction - sans support du tronc - avec support du tronc
50 75 55 75
62 275
55 225
Travail avec tout le corps (posture debout) : Poussée Traction
200 145
Travail du pied (posture assise avec support du tronc) : Action de la cheville Action de la jambe
250 475
D. Chablat - January 2016 83
Correction factors
• Execution speed of movement • Action time and frequency of the movement • The exercise duration value after correction remains a measure of the maximum
possible forces effort. • Account must be taken of factors affecting risk: use of additional weighting for
the calculation of the risk assessment force – Posture. – Precision of movement. – The potential acceleration. – The vibrations produced by the machinery. – The control of the pace of work. – The discomfort caused by personal protective equipment. – The thermal environment
D. Chablat - January 2016 84
Conclusion on muscles
• 15% of maximum strength • Short duration of contraction • Refer to the lowest muscle • Encouraging:
– Supports – Mechanical means – Breaks – Balanced diet and sufficient
D. Chablat - January 2016 85
Ergonomics study for a virtual mannequin
• The mannequin manipulation software tools feature an ergonomic analysis from the joint variables of the model and the mass of the transported object.
• The main methods are – RULA method (Rapid Upper Limb Assessment) – The method OWAS (Ovako Working Posture Analysis System) – The equations of NIOSH (National Institute for Occupational Safety and
Health) – The method BSHA (Burandt Schultetus-Hand-Arm Force) – The equations of Moore and Garg
D. Chablat - January 2016 86
Ergonomics study for a virtual mannequin
• Goals: – Being able to characterize the arduous a task – Preventing disease risk – Assess the feasibility of a task by a man or a woman
Evolution efforts on back
D. Chablat - January 2016 87
Ergonomics study for a virtual mannequin
• RULA method (Rapid Upper Limb Assessment) – It allows to quickly assess the risk of injury or fatigue associated with
posture of the neck, trunk and upper extremities, and muscle function and the stresses incurred by the body.
– A scoring system is used to establish a list indicating the level of interventions which act to reduce the risk of injury resulting from the physical load on the job.
http://www.ergonomics.co.uk/Rula/Ergo/survey_justright.html
D. Chablat - January 2016 88
©http://ergo.human.cornell.edu/ahRULA.html
D. Chablat - January 2016 89
Ergonomics study for a virtual mannequin
• The method OWAS (Ovako Working Posture Analysing System) – It allows to quickly assess the comfort
of a posture and the associated risks, from the back position, arms and legs, and the load supported through rating system.
D. Chablat - January 2016 90
Ergonomics study for a virtual mannequin
• The method OWAS (Ovako Working Posture Analysing System)
D. Chablat - January 2016 91
Ergonomics study for a virtual mannequin
• The equations of NIOSH (National Institute for Occupational Safety and Health) – They provide the mass of an object acceptable or unacceptable for a given
mass or the recommended posture for a two-handed lift a load when standing.
– This is calculated from the maximum mass that 99% of men can stand in a reference posture (standing, back straight, load increased to 2 hands against the body 75 cm from the body), the position of object with respect to the body, the displacement of the object during the lift, as well as the asymmetry of the load.
D. Chablat - January 2016 92
Ergonomics study for a virtual mannequin
• The equations of NIOSH (National Institute for Occupational Safety and Health) – RWL- Recommended Weight Limit – LC - Load Constant – HM- Horizontal Multiplier – VM- Vertical Multiplier – DM - Distance Multiplier – AM- Asymmetric Multiplier – FM- Frequency Multiplier – CM- Coupling Multiplier
D. Chablat - January 2016 93
Ergonomics study for a virtual mannequin
• The maximum weight specified by the standard is 23 Kg. • Achievable by 99% of men and 75% women. • HM parameters VM, FM, DM and AM are defined by graphs
depending on the distance and varies from 0 to 1.
(Ergonomics for beginners, J. Dul
and B. Weerdmeester,
Taylor & Francis)
D. Chablat - January 2016 94
Ergonomics study for a virtual mannequin
• Example: bring a suitcase
D. Chablat - January 2016 95
Ergonomics study for a virtual mannequin
• The method BSAHA (Burandt Scultetus-Hand-Arm Force) – Application for lifting operations. – The BSHA analysis method for analyzing the forces acting on one hand by
detecting the maximum permitted forces the hand-arm system of a human model can tolerate (and without back or legs).
– The analysis is based on intermediate values in accordance with the shape computing analysis.
• Input data – Personal settings, hand posture and direction of the forces, real force
• Results – A theoretical maximum allowable forces
D. Chablat - January 2016 96
Ergonomics study for a virtual mannequin
• BSHA method
D. Chablat - January 2016 97
Methods-Time Measurement (MTM)
• Description (www.mtm.org): – Use: Analysis method most used in industry – Principle: film studies and various industrial worker work – Baseline: Description of manual activities and elementary movements to
assess worker – Sensitivity: Time decomposed into elementary hundredth of an hour
micron (0.00001 hour = 0036 s = TMU = time measurement unit).
D. Chablat - January 2016 98
Methods-Time Measurement (MTM)
• Timebase example
D. Chablat - January 2016 99
Conclusions
• Properties virtual human simulation software – Calculation
• The accessible space • Field of view
– Ergonomic study • NIOSH (National Institute for Occupational Safety and Health) • RULA (Rapid Upper Limb Assessment) • OWAS (Ovako Working Posture Analysing System) • BSHA (Burandt Schultetus-Hand-Arm Strength / Hand-Force Analysis)
– Determination • The joint values • Energy expenditure • Static study
D. Chablat - January 2016 100
Conclusions
anthropometry
accessible volume
passage of hands
vision cone