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The sections below outline our suggestions for collecting high quality experimental data for use in analyzing human and animal motion and generating simulations.

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OTHER TIPS

• • As a general rule, you must place enough markers on your subject to scale and track each body segment you will model. You need at least three non-collinear markers to track the 6 DOF motion (position and orientation) of a body segment.
  • Try to place markers on anatomical locations that will have the least skin and muscle motion.
  • There are several OpenSim model marker sets that you can use and adapt, including:
    
    • Full-body model used for dynamic simulations of running by Hamner et al., 2010: https://simtk.org/project/xml/downloads.xml?group_id=516
  • To read more about markers sets for motion capture, please see the following references:
    
    • Cappozzo, A., Catani, F., Croce, U.D., Leardini, A., 1995. Position and orientation in space of bones during movement: anatomical frame definition and determination. Clinical Biomechanics (Bristol, Avon) 10, 171–178.

    • Davis R, Ounpuu S, Tyburski D, Gage J. A gait analysis data collection and reduction technique. Hum Mov Sci 1991;10:575–87.

    • Kadaba, M.P., Ramakrishnan, H.K., Wootten, M.E., 1990. Measurement of lower extremity kinematics during level walking. J. Orthop. Res. 8 (3), 383–392.

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• To improve scaling of the torso and lower extremities, you can calculate functional joint centers and append the joint centers to your static trial data (see __40__ Associating Data with a Motion).  
• Have your subjects perform movements to calculate functional joint centers at the hip, knee, ankle, and/or shoulders.
  
  • Hips & Shoulders: Have the subject move each arm/leg in a star pattern, raising and lowering their arm/leg 4 or 5 times as they rotate from an anterior position to a posterior position.
  • Knee: Have the subject do a knee squat. Repeat 3 times.
  • Ankle: Have the subject plantarflex their ankle and stand on their tip toes, then lower. Repeat 3 times.
• For more information about functional joint centers, please see the following references:
  

  • Gamage, S.S., Lasenby, J., 2002. New least squares solutions for estimating the average centre of rotation and the axis of rotation. J Biomech 35, 87-93. 

  • Siston, R.A., Delp, S.L. 2006. Evaluation of a new algorithm to determine the hip joint center. J Biomech 39, 125-130.

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