All Labs 1-5 Flashcards
what is anthropometry
anthropometry is the study of human body measurment
factors that anthropometry looks at
weight, size, dimensions, working capacity, strenght adn the difference between individuals
percentiles are specific to..
the population they describe
the dimensions they describe
population distrobution misuse
- people think 50% will accomodate majority of the population
- summating dimensions does not add to the percentile
Standard deviation
the degreee of variability in the population
coefficient of variation
another index for the degree of variability
where is the shortage of anthropometric data
canadian adults have a shortage of data
leptokurtic
tall skinny
platykurtic
flat broad
bimodal
ussaully the addition of two means to make two peaks from differetn data
positive skew
peak at the left
negative skew
peak at the right
when plotting in relation to increased cost we should
plot p agianst z - z being at the bottom ( cumulative) form
why do we plot p agaisnt z
becuase it will allow us to add more constraints as we increase the amount of users,
limiting user
adds the most sever design constraint
as we adjust the design by increasing the cost, we increase the limit of people it may accomodate
4 anthropemetric contraints
clearance - one way
reach - one way
posture - two way
strength - sometimes two and one way
Fitting Trial
a mock up wokrstation to get the dimensions of a person just right
psychophysical experiment
sunjective and psychological adjustments
standard anthropometric measures are made in which two ways
standard standing posture
standard sitting posture
clothing error
10mm indoor clothing
40mm outdoor clothing
shoe error
25mm - 45mm
interrater reliability
difference in measures betwen two people meausring (between)
intrarater reliability
difffernece in measures against ones self (within)
why uise interrater and intrarater reliability
to ensure standardization
what is the anthropometric inch
25mm of error between two measurments - if greater than we take a third measurment and averge the closest measurments
large anthropometer
0-60cm in 0.1cm increments
small anthropometer
0-30cm in 0.1cm increments
chest depth caliper
0-24 inches 1/2 inch increments
why use circuit order
increase standardization
reduce error
increase intrater reliability
what is gait
gait is the word to describe how locmotion occurs
types of gait
running and walking
defining difference between running and walking
running has a point of airborne time in which both feet are off the ground, walking always has one foot on the ground
phases of gait
swing and support
phases of support
double and single support
what is the most basic analysis of gait
linear kinematic analysis
why is linear kinematic analysis the the most basic type
because it looks only at the descripiton of velocitties and postions and acccelerations and not the cause of the postions and velocities and accelerations
estimated time of a gait cycle
1 second
how do we obtain kinematic data
high speed cameras, digitization and markers
stride phases and their %
swing and support
swing is 40% and support is 60% of the gait cycle
weight transfer between wlaking and running
runnning - weight transfers from limb to limb
walking - COM passes ofver the foot in anticipation for the transfer to the next limb
running velocity =
stride lenght x stride rate
how do we increase running velocity
increase stride lenght or stride rate
what runningn velocitiies consititue running vs walking
initial icrease in velocity up to around 7m/ s then no longer walking fast at around 2m/s
what is an angular kinematic analyis
angular kinematic analysis is a description of changes in joint angles during walking and running as a fucntion of time
angles of joints in ambulation
as we walk to make contact we see every joint flex and the ankle joint extend
as we push off we see joints extend and ankle joint flexwhr
were does the greatest range of motion occur
the saggital plane
increasing speed and jopint angles
increasing speedd we see an increase in felxion of joints except a decrease in plantar flexion of the anklejoint
toe off vs ground contact angels of hip knee and ankle
gorund contact we see highest in hip then knee then ankle in toe off we see low to high in hip knee then medium in ankle
active markers
emit a signal and activeate via signal
passive markers
relfective ciruclar markers on anatomical locations
rigid body dynamics
when two points are fixed with a third point moving to create traingle, the lones betwen them dontchange lenght
motion anlaysis system
measures the markers and gives coordinates
linear kinetics looks at
GRF
double support spike to 120 BW (accelerating the COM) then single 80 then double again increases
angular kinetics looks at
the forces that produce motion
muscle actions calculated via
muscular power of eccentric and concentric actions
muscular power =
net joint moment x joint velocity (angular) (Force of the joint x speed of the joint )
positive power
concetric contraction
negatie power
eccentric contraction( opposite direction of poisitive power)
pressure
force per unit of area N/m2
COP
the wieghted average of all of the downwards acting forces
what system did we use for gait lab
GAitRite
gaitrite looked at two parameters
temporal and spatial data
GAITRITE (looing at gait) can help with
refining orthotics and prosthetics
measuring post operation ambulation
selecting assitive devices (crutches)
velocity
distance / ambulation time
mean normalized velo
leg lenght / sec
gati lab obj
to examine linear kinematics manually by having students measure stride lenght and step lenght
difference between kinetics and kinematics
kinetics is the action of forces seen with motion
kinematics is the descriptions of the motions (time space variables)`
three laws of motion
F=ma
Objects in motion stay in motion
equal and opposite forces
force platform used to
measure GRf and COM
GRF data is recorded as …
BW instead of Newtons
GRFs are a function of
time
shear componenets are
Fx and Fy
Vertical component is greater than shear?
YES
Walking Vs Running VErtical GRF typical data
1-1.2 in walking and 2-5 in running
active vs passive peak
passive peak in bimodal is when the full load of the body is weighing down on the force platform (body is lowered force is greater than BW)
active peak is when the force of pushing off the toe is applied to the force platform
active is greater than passive -
active is the portion under muscular activity to accelerate body control
Passive is not any musular activity
Negative breaking Force
occurs during the Fy function and is when the force of the foot breaks throught the shear force of friction horizontally - occurs during the first half of support when touching the ground
psoitive propulsive force
muscles pushing back agianst the ground middistnace in Fy
Torque Mo is what
the force causeing rotation about an axis at a perpendicular distance away
Torque equation
Mo= Fr
calculating COP lets us
see the movement of the COP across the stance phase
AMTI Force Platform Directions usses what type of direction system and whats the directions
counterclockwise is postive and clockwise is negative
XYZ system orthogonal
Zo
the point from flat platform to middle of the connector
true origin
right hand rule
can calculate the direction of the vector using outstretched them when turning in the direction of rotation
Walking Gait Time Constant
200Hz x 2 sec
2/200Hz = 0.05
Running Gait Time Constant
200Hz x 1 sec
1 sec/200Hz = 0.005
COP Time Constant
10 secs 200 HZ
what is digitization
cobverting parts of an image to numerical position data
optoelectric motion capture
gets rid of the use of digitization as cmaeras sense markers located on anatomical positions of the body and feed the information inot the computer as it senses the signals IREDS or reflective passive markers
gold standard for a marker
anatomical 3 non - colllinear markers inside the bone at anatomocal locations
XSens MOtion capture lab uses what referecne system
2D/ 3d cartesian plane
2d 3d reference system alos know as
rectangular reference system
local refereence system
2D x and y that moves as the segment moves
horizontal x axis aka -
abscissa
vertical y axis aka
ordinate
what describes planar motion
2D reference system (vert and horizontal movement)
3D referernce system referes ot
x y and z orthongonal
y is up and down z is mediolaterl
statics
when the resulting acceleration is 0 or constant
dyanamics
when the resulting acceleration is non zero
forward dynamics
using Forces and moments to get acceleatio F=ma
inverse dynamics
using acceleration to get forces and moments a= F/m
to get Rx and Ry or Fx and Fy
the sum of of forces will equal masss x acceleration so if we have the acceleration adn mass we multiply them together adn notforget about the current forces acting and either add or subtract them from the obtained force of m x a
name multiple motion captrue softwares
JACK
3Dmatch /GOBER
XSens
VIcon
3DMatch
waterloo
uses 3d rigid links with a joint model to caluclaute peak loads and moments on l4/5
VICON
uses 53 motion caputre reflective passive markers
XSENS our main motion capture software
17 active markers
COnsiderations when designing a model
5
G - gold standard
- direct or valididty against another system
M - methods used to validate
MP - model purpose
MA - model assumptions
- rigid body
- fixed inertial properties
- complexity
P - problems with invaled models
- usefulness
- clinical applications
inverse dynamics assumes
each link has a fixed mass
each link has a centre of mass at a fixed point
the moment of inertia at any axis is constatnt
the body is made of frictionless pin points
the body is a rigid link segment
Work
Nothing much force x lenght displacement
velocity and speed
displacement and distance over time
