of the hip, knee and θthigh
ankle vs. time was
digitalized, and the
angle of the foot
above the ground
during any period of θ = Resulting Angle of
time was calculated Foot Above Ground
from this data. θankle
Digital Data Results
It was determined from the digital data that during footslap the
angular velocity of the foot of a healthy male runner was…..
V = -14.15 [rad/s].
The graph shows the angular displacement and velocity versus
DIGITALIZED DATA - Angular Displacement and Angular Velocity vs.
Displacement [rad] and Velocity/wn
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Angular Displacement Angular Velocity Poly. (Angular Displacement) Poly. (Angular Velocity)
The purpose of the model was to
simulate the position and velocity of
the foot from the heelstrike to
footslap period of the Gait cycle. Weight
The simulation results would then
be compared to the results of the
digital data to obtain an accurate
magnitude of ankle stiffness in a
healthy male runner.
θF = angle of the foot measured LT Ka,Ca
from the ground to the bottom of the
LH = length of foot from heel to
Ka and Ca = spring stiffness and
The simulation was run with a zero stiffness in
order to find the angular velocity of footslap that
Jason would experience without the brace.
Angular Velocity (k=0) = -25.3 [rad/s]
This is significantly more then the footslap
velocity calculated from the digital data (V =-
The correct stiffness value was determined by
varying the value of stiffness until the simulation
results matched the digital data results.
Simulation to Find Stiffness
Itwas found that will a spring stiffness of
k=117 [Nm/rad] the footslap velocity of the
simulation would be equal to that of the
digitalized data (V=-14.15 [rad/s]).
The following graph illustrates the
Displacement and Velocity of the foot for
the digital data and the footslap.
Dgital vs. Simulation Data for Displacement and Velocity
Displacement (rad) and Velocity (rad/s)
0 0.05 0.1 0.15 0.2 0.25
Digital Displacement Digital Velocity Simulation Displacement
Simulation Velocity Poly. (Digital Displacement) Poly. (Digital Velocity)