Ergo Biomech 2008

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ERGONOMICSERGONOMICS

DR. SITI ZAWIAH MD. DAWALDR. SITI ZAWIAH MD. DAWAL

DEPT. OF ENGINEERING DESIGNDEPT. OF ENGINEERING DESIGN

AND MANUFACTUREAND MANUFACTUREUNIVERSITY OF MALAYAUNIVERSITY OF MALAYA


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ERGONOMICS

and BIOMECHANICS

Copyright @ 2008 by ERGO


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IntroductionIntroduction

Bio- life or way of life in GreekBio- life or way of life in Greek

Mechanics branch of science dealsMechanics branch of science dealswith forces and effect of forces.with forces and effect of forces.


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Three disciplinesThree disciplines

Mechanics of rigid bodyMechanics of rigid body

Mechanics of solid deformable bodiesMechanics of solid deformable bodies

Fluid mechanicsFluid mechanics


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Mechanics- Forces and MotionMechanics- Forces and Motion

Description and analysis of motion -kinematicsDescription and analysis of motion -kinematics

Description and analysis of forces kineticsDescription and analysis of forces kinetics

Description and analysis of forces tend to causeDescription and analysis of forces tend to cause

motion -staticsmotion -statics


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Kinematic concepts forKinematic concepts for

analyzing human motionanalyzing human motion


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The SkeletonThe Skeleton


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General FunctionsGeneral Functions

Gives the body its basic shape andGives the body its basic shape and

provides a strong , protective andprovides a strong , protective and

supporting framework for all other systemssupporting framework for all other systems

of the body.of the body.

With regards to movement the bones ofWith regards to movement the bones of

the skeleton act as a levers operated bythe skeleton act as a levers operated by

the skeletal muscles.the skeletal muscles.


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Mechanical FunctionsMechanical Functions

At birth 270 bonesAt birth 270 bones

Adults 206 bonesAdults 206 bones

4)4)Acts as a supporting framework for theActs as a supporting framework for the

rest of the bodyrest of the body

5)5)Acts as a lever system muscleActs as a lever system muscle6)6)Protect certain organsProtect certain organs


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Anatomical Reference PlanesAnatomical Reference Planes

Median Plane or Sagittal plane verticalMedian Plane or Sagittal plane vertical

plane that divide the body - left and rightplane that divide the body - left and right

portions.portions.

Coronal plane or Frontial plane verticalCoronal plane or Frontial plane vertical

plane perpendicular to median plane.plane perpendicular to median plane.

( anterior and posterior)( anterior and posterior)

Tranverse Plane horizontal planeTranverse Plane horizontal plane

perpendicular to both median and coronalperpendicular to both median and coronal

planes.planes.


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Types of movementsTypes of movements

See handoutsSee handouts


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Newtons 1Newtons 1stst Law of MotionLaw of Motion

A body which is at rest will remain at restA body which is at rest will remain at rest

unless some external force is applied to itunless some external force is applied to it

and a body which is moving at a constantand a body which is moving at a constant

speed in a straight line will continue to dospeed in a straight line will continue to do

so unless some external force is applied toso unless some external force is applied to

it.it.


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Newtons 2Newtons 2ndnd law of Motionlaw of Motion

Force = mass x accelerationForce = mass x acceleration

F =F = mm x ax a

The relationship between force, theThe relationship between force, the

resulting motion of a body and theresulting motion of a body and the

properties of the body itself.properties of the body itself.


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Newtons 3Newtons 3rdrd Law of motionLaw of motion

To every action force there is always opposed anTo every action force there is always opposed anequal reaction force orequal reaction force or

The mutual action forces of two bodies upon eachThe mutual action forces of two bodies upon each

other are always equal and oppositely directed.other are always equal and oppositely directed.


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Moment of ForceMoment of Force

= W x distance X= W x distance X11

Where W is the magnitude of theWhere W is the magnitude of thegravitational force e.g. weight of the bootgravitational force e.g. weight of the boot

and Xand X11 is the perpendicular distanceis the perpendicular distance


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How would you represent the line ofHow would you represent the line of

gravity of the patient in each of thegravity of the patient in each of thediagrams given. (approximate position)diagrams given. (approximate position)

Tutorial

Copyright @ 2008 by ERGOCopyright @ 2008 by ERGO


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Centre of GravityCentre of Gravity

The centre of gravity (C of G) of an objectThe centre of gravity (C of G) of an object

is the point at which all of the weight of theis the point at which all of the weight of the

object may be considered to beobject may be considered to be

concentrated and about which the objectconcentrated and about which the object( in theory) exactly balance.( in theory) exactly balance.


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Machines and mechanismMachines and mechanism

Rehabilitation machines are devices thatRehabilitation machines are devices that

have been developed to provide specifichave been developed to provide specific

movements for limbs or joints or to providemovements for limbs or joints or to provide

specific resistance to muscle actionspecific resistance to muscle action


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MechanismMechanism

Mechanism such as lever used inMechanism such as lever used in

machines to transform motion and /ormachines to transform motion and /or

force into a desired output.force into a desired output.


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LeverLever

A lever is a rigid beam pivoted at a pointA lever is a rigid beam pivoted at a pointknown as the fulcrum.known as the fulcrum.

There are three classes of leverThere are three classes of lever - First order lever- First order lever

- Second order lever- Second order lever - Third order lever- Third order lever


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Inclined PlaneInclined Plane

Inclined plane is a good example of aInclined plane is a good example of a

method used since ancient times to raisemethod used since ancient times to raise

heavy loads with a relatively small effort.heavy loads with a relatively small effort.


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Tutorial 1Tutorial 1

2) Refer to the 12) Refer to the 1stst Q comment on theQ comment on the

stability of the subject in each position.stability of the subject in each position.

3) Refer to figure 2, assume that the3) Refer to figure 2, assume that the

combined weight of a patient and a wheelcombined weight of a patient and a wheel

chair is 800N and the therapist is requiredchair is 800N and the therapist is required

to push the wheelchair up a ramp that hasto push the wheelchair up a ramp that has

a slope of 1 in 10. Calculate the minimuma slope of 1 in 10. Calculate the minimumforce that the therapist must apply to pushforce that the therapist must apply to push

the chairthe chair

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Ergo Biomech 2008