Week 1: Basic biomechanimal concepts Flashcards
what are the numerous fields that contribute to biomecs
math, physics, engineering
biologyc, chem, physiology
health sciences, med
where is biomecahncs used
sports, ergonomics and design, medecine and surgery (cardio, neuro, ortho) rehab
fancy definition of kinematics
study of motion without regard to the forces that cause that motion
velocity, accetable, jt angles are associated with kinematics or kinetics
kinematics
torque is associated to kinetics or kinematics
kinetics
in kinematics what are the 2 types of movement possiblr
1) translation
2) rotation
explain translation in terms of kinematics
all points on body move the same distance
explain rotation in terms of kinematics
there is a stationary point (COR) and all points move in an arc around that stationary point
what type of movement is most common in the buman body and explai n
rotation
=rotation occurs at the joints
=there are some translations that occur with the rotation but very small movements
injuries can increase rotational or translational movment
translation
what are the 4 kinematic variables
position
displacement
velocity
acceleration
explain position
where you are
explain displacement
change in position
explain velocity (formula)
change in position/time
displace/time
explain accelration (fromaula)
change in velocity/time
velocity has two components and speed only has one. what are the componenets of velocity
its a vector so it has both magnitude and direction
what are the 3 axis in the coordinate system
anterior/posterior
superior/inferior
medial/lateral
what are the 3 planes of the coordinate system
saggital
frontal/coronal
transverse
sagital splits the body into what
l/r halves
frontal splits the body into what
anterior and psoterior halves
transverse splits the body into what
up and dwon
planes rotate around the axis that are BLANK to it
perpendicular
what are the 2 axis of the sagital plane
super/inferior
anterior/posterior
what are the 2 axis of the frontal plane
super/inf
med/lat
what are the 2 axis of the transverse plane
med/lat
ant/post
explain the axis and plane of shoulder abduction
moves in the coronal plane along the ant/post
explain the axis and plane of shoulder flexion
rotation in sagital plane about med/lat
global coordinate system has how many dimensions
3
what is the difference between global and local coordinate systems
global: fixed to some point in space
local: fixed to a rigid body (ex: femur)
explain local/anatomic coordinate system
seperate coordinate systems per segment and joint angles is how they move relative to each other
two local coordinates (eg: knee and femur) are often compared to determine what
joint angles
in our global coordinate system, how many degrees of freedom do we have
6 degrees of gfreedom
what does it mean to have 6 degrees of freedom of movement
it means there are 6 wways to move in 3 dimensional space
with 6 degrees of freedom you can translate and rotate along what axes
3 axes
true or false: there are 6 DOF in joints of the body
false, there are less than 6 DOG in joints because of contraints (joint surfaces, ligaments, etc)
how can we translate along the 3 axis
forward/bnackwars
right/left
up/down
how can we rotate along the 3 axis
roll
pitch
yaw
what is force
a push or pull acting on a body (F=massx acceelation)
what is the formula for force
F= mass x acceleration
what is the units for force
newtons ( N= kg*m/s2)
name some common forces:
muscles, ligaments, ground reaction, weight (gravity)
what is moment (torque)
force acting at a distance from center of rotation
what is the formula for moment/torque
M = moment arm x force
what is the unit of moment/torque
measured in New*Meters
Nm= kg*m2/s2
what is newtons 1st law
an object remains at rest (or continutes moving at a constant velocity) unless acted upon by an unbalanced extermal force
SigmaF=0. SigmaM=0 (sum of all forces/torques = 0 )
what is the significance of newtons 1st law
will be used to help solve forecs and moments in static bodies
what is newtons 2nd law:
If there is an unbalanced force acting on an object, it produces an acceleration in the direction of the force, directional proportional to the force
what is the formula for newtons 2nd law
F=ma
what is the significace of newtons 2nd law
will be used to help solve forces and moments in accelerating bodies
what is newtons 3rd law:
for every action (force), there is a reaction (opposing force) of equal magnitude but in the opposite direction
what is the significance of the 3rd newton law
will be used to measure external forces acting on the body (ex: GRF)
what is anthropometry
study of the physical measurements of the human body
what do anthropometrics measure
segment length, segment mass, centre of mass location, radius of gyration (resistance to rotation)
what is the centre of mass/center of gravity
point on which any line passing through it divides the bodys segments mass in half
true or false: around the centre of mass, the mass is equally distributed around this point
truw
does center of mass change with movement
yes
are you more stable when your center of mass is in or OUTSIDE your pass of sjupport
in (you are less stable outside your base of support)
what do motion capture systems do for kinematics
measure position (calculate velocity, acceleration ,joint angles)
what are the current motion capture systems we are using
optoelectric
electromagnetics
ultrasound
historically, what was used to capture motion
cameras and movie/television cameras
what is the principle of optoelectric systems
markers emit (active) or reflect (passive) infrared light, cameras identity marker position
what is the principle of electromagnetic systems
receivers (markers) pick up magnetic field emitted by a transmitter
what are the advantages of optoelectric systems
high accuracy
can be wireless
not influenced by materials
what are the disadvantages of optoelectric systems
markers can be occucluded (blocking each other)
post-processing time with some systems
what iare the advantages of electromagnetic systems
clear line of sight not necessary
what are the disadvantages of electromagnetic systems
metal interferance
limited range
wires
what are the 4 motion captures capabilities
1) cameras
2) optoelectric, electromagnetic, ultrasound
3) inertial sensors
4) markerless systems
explain inertial sensors for motion caputuring
combination of accelorometers (acceleration/inclination), gyroscopes (orientation), magnetometers (horizontal position)
explain markerless systems
multiple cameras getting 3D image (use contrast, machine learning = computer can automatically detect and label joints)
what are electrogoniometers used for and how
to measure joint angles during movement
by change in electrical current when device is bent
what is the advanaage of electrogoniometeers
cheap, simple
what are the disadvantages of electrogoniometers
difficult to align, movement can be limited by device
what do acceleratomets measure
acceleration
what can accelorometeres determine
net forec (F=ma), velocity or disaplacement
what is the instrumentation used for kinetics
force transducers and force plates
dynammometers
electromyography
pressure sensors
what do dynamometers measure
strength (force)
ex: isokinetic dynamometers, hand help., grip strenght
what does electromyographt measure
measures muscle activation during different activities
true or false: electromyography measures muscle force
false, it does not
when are pressure sensors usually used in kinetics
often used to measure plantar pressure
