Visual3D

Inverse Dynamics and

Joint Power Analysis

Biomechanics Laboratory, School of Human Kinetics

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 (via a pipeline) or manually with Visual3D

• special events used for reports can also be added– e.g., Begin, End, Impact

• events may be checked for

accuracy using GUI

Biomechanics Laboratory, School of Human Kinetics

Signal and Event Processing Screen

• signals and events tab

• edit events

• 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 • load/save scripts

Biomechanics Laboratory, School of Human Kinetics

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