The SPARK performs both a static and dynamic calibration each time the SPARK
is donned and used.
The static calibration is performed while the user is standing still, after donning
the SPARK. Device torque is measured by the torque sensors in each ankle
actuator, and is tared during the static calibration to eliminate bias in the
measured torque signal that can affect control of the SPARK system.
The dynamic calibration begins after the user starts walking during a trial.
Dynamic calibration quantifies the pressure threshold used to determine the
stance and swing phases by logging the maximum and minimum pressure
sensor signal for each step taken. The dynamic calibration also quantifies the
baseline peak pressure (average peak pressure during the initial steps).
The prescribed torque profile is generated by taking the instantaneous pressure
sensor signal and normalizing it by the baseline peak pressure value. The
resulting normalized signal is bounded by values 0 and 1.5, with the value 1.0
corresponding to the peak torque setting. For example: if a value of 30% or 15 Nm
is entered in the app, the controller will specify a peak prescribed torque of 15 Nm
when the normalized pressure sensor signal is equal to 1.0.
Assistive/resistive torque is not applied until the dynamic calibration is complete
and the pressure sensor baseline is established.
NOTATIONS USED
Warnings & Cautions used throughout this manual:
WARNING:
Describes potential safety hazards, limitations in use as a result of the
potential safety hazard, and steps that should be taken if a safety hazard occurs.
Caution:
Information about any special care to be used for the safe and effective
use of the device. Not following this information could lead to damage of the
device or lead to a poor participant experience.
Note: Information that’s helpful to use the device correctly.
REC-184 Version 0
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