measurement exam -red Flashcards
state the two types of 2D Kinematics
- Linear kinematics
2. Angular kinematics
State the Frame (sample) rate calculation.
The sample rate is based upon velocity data for walking and running.
With the use of an onlin vision research tool we identify a suitable frame rate.
Why is the sample frame rate information important?
It helps in the process of research protocol. First we calculate the appropriate frame rates. This then allows us to set up the data collection area (according to those measures). Set up cameras and collect test data.
The sampling frequency or sampling rate, fs, is the average number of samples obtained in one second (samples per second), thus fs = 1/T.
state performance variation
‘repetition without repetition’ (Bernstein, 1967). Implies
that a repeat performances will never be the same
These are the implications of visual identification of image data points.
State the Frame (sample) rate calculation.
The sample rate is based upon velocity data for walking and running.
With the use of an online vision research tool we identify a suitable frame rate.
what does the term coplanar mean
within the same plane
when is 2D a suitable option for data collection.
Two-dimensional filming / analysis is suitable for position estimates of objects on
a plane or movements occurring in a plane.
– Examples: ball-surface impacts, straight line running, etc.
• Predicated on the assumption of coplanarity
state and explain 4 camera based measurement tools
Stereophotogrammetry
• 3D motion capture
• Depth-cameras (show and tell)
• Synchronicity
state, explain and evaluate sensor based measurement
IMUs
explain the different 3D motion capture.
passive, multiple.
what is a gyroscope
A gyroscope is a device that uses Earth’s gravity to help determine orientation.
explain traumatic injuries and human impacts
Blunt force trauma; infrequent, high-force impact
– E.g. Commotio cordis in baseball
– Highlights requirement of personal protective equipment (PPE) in sport
explain chronic/ overuse injuries and human impacts
Chronic, repetitive loading; accumulation of low-force impact (cp. bone tolerance)
– E.g. Medial tibial stress syndrome in running
– Highlights need to understand biomechanics of running
name some human impact measurement devices
Measurement devices capable of directlymeasuring force
• Force platform and load cells (force applied at a point)
• Pressure platform (force applied over an area)
• *Isokinetic dynamometer (joint forces; not used in impact assessment)
– Measurement devices capable of indirectlymeasuring force
• Accelerometer (a = F / m)
How are impacts interpreted?
Vector quantities such as magnitude and direction.
State the mechanical derivatives that can also provide other ways of characterising impacts.
Acceleration- e.g. in tennis by measuring the impact acceleration that the racket endures this can help to identify the rackets sweet spot. This impact will be shown through vibrations. So we can use an accelerometer as an indirect measure of force to understand the impact force produced.
another example is zepp tennis which is a triaxial gyroscope and dual accelerometer.
Acceleration can also be used as a mechanical derivative to characterise head impacts. Such as the head impacts of CTD headform. This impact acceleration can then be used to design/re-design the properties of helmets. e.g. head impact crtierion HIC.
velocity, momentum, impulse
energy, power.
Name a device that uses the mechanical derivative acceleration to characterise equipment impacts.
Accelerometers. (This can be an indirect measure for force as well).
Explain the use of the mechanical derivative acceleration to characterise head impacts.
Head impact (CTD headform)
• Measuring impact acceleration experienced by the head can help assess
protective properties of helmets etc. (e.g. Head Impact Crtierion (HIC))
Define Newtons law of gravitation
‘particles’ are attracted to other ‘particles’
state the properties of attraction or force
- Directly proportional to product of masses
- Inversely proportional to distance between centres
What are the units of pressure
Pressure is typically measured in units of force (N) per unit of surface area (m2^)
• SI unit: Pascal (Pa) which is equal to 1 N/m2 or kg·m-1
·s-2.
how do we quantify variance
Mean and standard deviation of the differences or errors (e.g. systematic and random errors)
– Coefficient of variation: standardised measure of error distribution (e.g. precision)
• Given as: Cv(%) = (standard deviation ÷ mean) × 100
What are the requisites of data captured in sport and exercise?
Accuracy
– Validity
– Precision or reliability
– Objectivity
– Minimal error propagation, i.e. during subsequent calculations
– Comprehensibility
• List selected from Mullineaux et al. (2001) and Mullineaux and Bartlett (1997)
how do you calibrate and verify gas analysis measurements
calibration curves. gold standards
what is the best way to verify a gas.
compare against the gold standard
define cross validation
The same measurements are made on a smaller sample taken from the original population to check whether the prediction is accurate
define precision
“precision” and “trueness” to describe the accuracy of a measurement method.
so precision refers to the closeness of agreement between test results.
define trueness
“precision” and “trueness” to describe the accuracy of a measurement method.
Name two types of team positioning systems
- Vision-based positioning technologies
2. Player-worn technologies (wearables)
what are the pros and cons of GPS and LPS.
GPS sensors are simpler to setup (just require sensor) but do not function indoors
– LPS sensors are more complex to setup (require multiple base stations around pitch) but do function
indoors
– Validity of position measurement for both systems are affected by player movements such as running,
sprinting and changes of direction
what are criterion measures
Criterion validity (or criterion-related validity) measures how well one measure predicts an outcome for another measure. A test has this type of validity if it is useful for predicting performance or behaviour in another situation (past, present, or future).
define sample rate
In audio production, a sample rate (or “sampling rate”) defines how many times per second a sound is sampled. Technically speaking, it is the frequency of samples used in a digital recording.
advanced image measurement
this is the complex use of photography in order to derive measurements via multiple images.
