Activities Based on the Walking Data for Subject Maira
Motion and force data were taken for subject Maira as she walked steadily in a straight
line at the Chapin Gait Analysis Center. The data are in an Excel spreadsheet file,
MairaWalk3AA.xls. A video and two animations of her motion are also available. The
video is on the file MairaWalking3.mpg. A stick figure animation showing recorded
force vectors is on the file MairaWalk.mov. A stick figure animation showing the paths
of various body parts is on the file MairaWalk3_contrails.mpg.
Conceptual Activity:
1. Stand up and walk at a constant velocity for a few steps. Think about how your body
moves during this time. Do you think all your body parts move at constant velocity
during the walk?
2. Observe the animation MairaWalk3_contrails.mpg. Are there any body parts shown
that actually move in a straight line?
3. What is happening in the vertical direction for all of the displayed body parts as
Maira walks horizontally?
4. Observe the animation MairaWalk.mov. As Maira steps on a force plate, the
animation shows the net force vector. Describe what happens to the direction and
magnitude of the force vector as a step is taken.
5. Do the direction changes of the force vector on the foot during the time of a step
make sense to you?
6. Make a graph of the x-coordinate versus time for the Top Head (X1) and the Right
Heel (X18). Does the head move for the entire time period? Does the heel move for the
entire time period?
7. Make a graph of the z-component of force versus time for force plates 2-4. Describe
the shape of this component over the course of a step. How does this shape correlate
with what is happening to the heel and toe during a step?
Analytical Activities:
1. Develop a spreadsheet that can estimate instantaneous velocity from the position
data for any selected body part.
2. Use the velocity spreadsheet to compare velocities of the Top Head, wrist, and heel.
Write an essay describing the comparison. You might address questions such as
whether any of these parts ever stop during a steady walk.
Synthetical Activities:
1. Look carefully at the vertical (z) component of force during a step. How does the
magnitude compare when the heel is in contact with the floor and when the toe is in
contact?
By observing the animation file MairaWalking.mov you can recognize that the force
plate is measuring the force on one foot. By using this knowledge of the force on one
foot, develop an estimate of the total vertical force on Maira as a function of time.
2 Develop an estimate of the total horizontal force on Maira as a function of time.
3. Develop a spreadsheet that can estimate the position of the center of mass of each
body part described in the file HumanAnthropomorphicData.doc.