Optoelectronics & Modelling Flashcards
What are the applications of motion analysis optoelectronics?
Technique analysis
Gait analysis
Injury risk factors
Movement variability
What are five variables motion analysis-optoelectronics is able to measure?
Joint angles
Velocities
Acceleration
Muscle moments
Internal forces
What are optoelectronics?
Special high-speed cameras (infra-red light or visible light emission cameras).
What are active markers?
Markers mounted on the subject which emit or reflect infra-red light.
What are passive markers?
Hemispherical, made by retro-reflective paper.
What are the four advatages of optoelectronics?
Rapid analysis = Automatic digitising
High resolution = Accurate results
Field-based
Useful for finer movements
What are the disadvatages of optoelectronics?
Number/location of cameras
Marker dropout
Gap filling
Visual 3D software required (some systems)
No visible image of the movement is obtained
Sensitive to sunlight
Limited marker detector distance
What is modelling?
The process of defining a representative, alternative system.
What is simulation?
The application of this defined ‘model’ to run many virtual experiments
What is Inverse dynamics modelling?
Determines internal forces based on resulting motion.
Calculates:
– Joint moments
– Joint reaction forces
What is Forward dynamics modelling?
Determines segment motion based on internal forces.
These types of models can be driven by:
– Angles
– Forces
How does Optoelectronics work?
Usually based on 6-12 cameras around a measurement volume (but can be any number).
Markers placed on anatomical landmarks / joint centers.
Each camera has light emitting diodes which flash and its position is recorded by each camera.
Each camera’s data is taken and the computer “reconstructs” the data to provide coordinates for each marker.
How is Optoelectronics calibrated?
Each manufacturer has their own calibration procedure.
Common method is to place an object on the floor in the movement volume (static calibration - sets origin of lab space).
Wand of known dimensions is moved through the entire movement volume (dynamic calibration).
