Sensors and Feedback Hardware

Sensors

Pressure sensors: A total of four Force-Sensing Resistors (FSR) are embedded in commercially-available insoles. These are used to determine the GRF during both Gait and Training modes. For each insole, one sensor is located at the heel and another is at the toes. FSRs were chosen due to their size, geometry, and material compliancy, which enables ease of integration with the insoles, low cost, and good shock resistance.
Inertial Measurement Units (IMU): Three IMUs are used for evaluation of the gait kinematics. The IMUs are located on the foot, lower, and upper and segments of the affected limb.

Bone-conducting headphones: A pair of bone-conducting headphones is used to provide auditory and vibrotactile feedback to the user. This technology is particularly suitable as, unlike traditional headphones, they do not isolate the user from the surroundings, which may cause additional distress to stroke survivors. Moreover, unlike wearable loudspeakers, their performance would not be affected by potential hearing loss, which is common in the elderly population. Auditory feedback is provided using pre-recorded messages that inform the user when abnormalities are detected in their walking during Gait mode. This can be accompanied by slight vibrations to the mastoid bone. Moreover, auditory feedback is used to notify the user about their progress during Training mode, and to provide them with vocal instructions during both the modalities.

Datasheets can be found here.

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