2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
A hole was drilled through the sole of the boot in the heel region. The sole of the boot was
then connected to a fixation plate with a screw through the hole in the sole (Fig. 3). The
bottom of the fixation plate was fixed to a 6 DOF force/torque sensor (JR3 Inc, Woodland,
CA) (Fig. 4).
Figure 3. Fixation plate is Figure 4. Fixation plate is
fixed to the JR3 sensor fixed to the JR3 sensor
In the initial position the tibia of the foot model was perpendicular to the fixation plate. The
robot was programmed to make an ankle rotation of the foot model in the sagittal plane.
The resistance of the boot to the ankle rotation in the sagittal plane results in Ty (torque y) of
the JR3 sensor.
RESULTS
Three candidate army boot models were tested for ankle sagittal stiffness (Fig. 5). Ty and φ
(angle of the rotation) were measured during the rotation of the foot model in the sagittal
plane. The Ty/φ characteristic determines the boot sagital stiffness (Fig 6).
Fig. 5. Three army boot candidates tested for ankle sagittal stiffness.
The Ty/φ characteristics show significant differences in ankle sagittal stiffness of the three
boots tested. Boot 1 had a very low stiffness, which was generated mainly by the tongue.
Boots 2 and boot 3 had higher shafts therefore higher ankle sagittal stiffness was measured for
both models. Similar characteristics of the ankle joint rotation in the sagittal plane were
observed for both models in the range 0° to 5°. From 5° and up boot 3 had higher ankle
sagittal stiffness.
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Foot model
Boot
Robot gripper
3 DOF knee joint
Fixation plate
Robot frame
Fixation plate
JR3 sensor