Transcript Slide 1

Visual3D
Inverse Dynamics and
Joint Power Analysis
Marker and Force Data
• marker data come in a .C3D file created by Vicon, Motion
Analysis, Qualysis or similar motion capture system
• SIMI and APAS may also be used but data must be placed in a
ASCII (.FSV) file by, for example, BioProc2/3
• force data come with the .C3D file but may also be collected and
placed in an ASCII (.FSV) file by BioProc2/3
• data may be streamed directly to Visual3D using newest version
of Visual3D and compatible motion capture system, e.g., Nexus
Biomechanics Laboratory, School of Human Kinetics
Creating the Model
• first a static trial is loaded to create the model (you can use a
movement trial)
• a previous model may be used for a similar marker set
• model is customized for each participant (mass and height etc.)
• ideally markers are located at each joint but these markers do
not have to be included in the movement (dynamic) trials
• should save the model file (.MDH) separately for use with other
trials or experimental conditions of the same person
• new models must be created for each new marker set
• modeling is done using graphical user interface (GUI)
Biomechanics Laboratory, School of Human Kinetics
Model Building Screen
•
create segments
•
create landmarks
•
enter body mass
and height
Biomechanics Laboratory, School of Human Kinetics
Movement Trials
• one or more movement trials may be loaded into same
workspace (.CMO), essential if trials are to be averaged
• model is applied to each trial
• trial may be viewed with bones or geometrical solids for each
segment
• ground reaction forces should be checked
• errors in force platform locations and parameters may be
checked and changed in necessary
Biomechanics Laboratory, School of Human Kinetics
Workspace Screen
•
static trials
•
movement trials
•
tags to identify
experimental
conditions
Biomechanics Laboratory, School of Human Kinetics
Event Labeling
• if events were not created by motion capture software they can
be added automatically or manually with Visual3D
• special events used for reports can also be added
• events may be checked for accuracy using GUI
Biomechanics Laboratory, School of Human Kinetics
Signal and Event Processing Screen
•
event button
•
signal tree
•
body at current
event
•
signal histories
with events
marked
Biomechanics Laboratory, School of Human Kinetics
Data Processing Pipeline
• a pipeline may be applied to process the data for inverse
dynamics, energy or moment power analyses
• a script may be used to perform these operations
• a typical script (.V3S) includes interpolation and data filtering
• special forces may be added such as moving force platforms or
pedal forces
Biomechanics Laboratory, School of Human Kinetics
Pipeline Form
• commands
• pipeline
• options
• import signals
Biomechanics Laboratory, School of Human Kinetics
• load/save scripts
Graphical Reports
• reports including graphs of the various kinematics and kinetics
are created last
• special filters may be used to display only certain types of trials,
e.g., right vs. left leg starts, barefoot vs. shod gait, loaded vs.
unloaded lifts
• these categories are created in the workspace area
• basic reports (.RGT) may be loaded or created and saved for
later repeated use graphs may be exported for presentation
Biomechanics Laboratory, School of Human Kinetics
Reporting Screen
•
contents of pages
•
report pages
•
graphical or
tabular reports
Biomechanics Laboratory, School of Human Kinetics
Export Data to MatLab or BioProc3
• kinematic or kinetic data may be exported in .C3D or ASCII files
• BioProc3 has capability of computing total, internal and external
work, angular impulses and work done by individual bursts of
power
• script is used to create ASCII file for BioProc3
• MatLab can compute foot clearance
Biomechanics Laboratory, School of Human Kinetics
BioProc3: External/Internal/Total Work
• external work
• internal work
• total work
Biomechanics Laboratory, School of Human Kinetics
BioProc3: Work Done in Bursts
• work done
• which moment
of force
• peak power
• peak moment
• mean power
• total work done
Biomechanics Laboratory, School of Human Kinetics