D2.1 Requirements and Specification - CORBYS

D2.1 Requirements and Specification
10.2.3 Mechanical sensors
10.2.3.1 Pressure/Force sensors
Force and force distribution (pressure) sensors are widely used in biomechanics and gait analysis in
particular. There are several flexible thin force and pressure sensors on the market, e.g. from
Tekscan 11 . Pressure sensors are comprised of numerous individual sensing elements and a
corresponding sensor map and complex software are necessary to decode the signal. Tekscan have
e.g. systems for in shoe, as shown in Figure 22. The complex pressure sensors might be difficult in
real time evaluation and feedback in CORBYS gait rehabilitation system. Force sensors can detect
and measure a relative change in force or applied load to a surface, detect and measure the rate of
change in force, identify force thresholds and trigger appropriate action and detect contact and/or
touch. Tekscan standard force sensors are shown in the far right image in Figure 22.
Figure 22. Tekscan F-Scan® System ,
an in-shoe plantar pressure analysis (left and middle-left), and FlexForce A201 sensors, standard lengths from 19.7 cm to 5.1
cm, with sensing area diameter of 0.95 cm (middle-right ) and FlexForce A401 sensor with sensing area diameter of 1 cm.
10.2.3.2 Joint angular sensing
Goniometers are devices capable of transforming an angular position into a proportional electrical signal.
Commercial sensors for biomechanics applications are available, like the Plux 12 goniometer angelPlus, and the
twin or single goniometers from Biometrics Ltd 13 (Figure 23). A torsiometer will detect the torque on a shaft
by measuring the twist of a given length of the shaft. Single axis torsiometers are designed for measurement
of rotations in one plane, e.g. forearm pronation/supination or neck axial rotation. Torsiometers are available
from e.g. Biometrics Ltd (Figure 23). All these sensors must be attached to the skin using glue.
11 http://www.tekscan.com/
12 www.plux.info/angle
13 www.biometricsltd.com/
Figure 23: Goniometers from Plux (left) and Biometrics Ltd
(twin axis in middle left, single axis in middle right, single axis torsiometers to the right).
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