Fall detectors and a method of detecting falls
There is provided a fall detector for detecting falls of a user or an object to which the fall detector is attached, characterized in that the fall detector comprises an air flow sensor for providing measurements indicative of vertical velocity and/or changes in altitude of the fall detector.
1. A fall detector for detecting falls of a user or an object to which the fall detector is attached, the fall detector comprising:
an air flow channel;
an air flow sensor disposed adjacent the air flow channel and configured to measure air flow along the air flow channel;
an accelerometer configured to measure accelerations of the fall detector;
a processor configured to:
estimate an orientation of the fall detector from the measurements from the accelerometer,
estimate a vertical velocity from the measurements from the air flow sensor and the estimated orientation,
estimate a change in altitude from the estimated vertical velocity,
determine whether a fall has occurred based on the estimated change in altitude.
2. The fall detector as claimed in claim 1 , wherein the air flow sensor is a thermal air flow sensor.
3. The fall detector as claimed in claim 2 , wherein the thermal air flow sensor senses air flow velocity in the air flow channel based on temperature measurements.
4. The fall detector as claimed in claim 1 , further including:
an alarm configured to be triggered by the processor when the processor determines that a fall has occurred.
5. A fall detector for detecting falls of a user or an object to which the fall detector is attached, the fall detector comprising:
an air flow sensor configured to provide air flow measurements indicative of air flow velocity, the air flow sensor including:
an air flow channel, the air flow measurements being indicative of an air flow velocity in the air flow channel,
an electrically driven thermal element on a front side of the thermal air flow sensor arranged to face the air flow channel, and
a bond pad coupled electrically to the electrically driven thermal element, the bond pad being arranged to face away from the front side to be accessible for contact from a backside of the air flow sensor, the air flow measurements being output via the bond pad,
an accelerometer configured to measure accelerations of the fall detector; and
a processor configured to process the air flow measurements from the bond pad and the thermal element and the acceleration measurements from the accelerometer to determine whether a fall has occurred.
6. The fall detector as claimed in claim 5 , wherein the air flow sensor further includes:
a conductive layer on the front side of the air flow sensor configured for electrical connection between the electrically driven thermal element and the bond pad, and the bond pad comprises a back side of the conductive layer.
7. The fall detector as claimed in claim 6 , wherein the air flow sensor further includes:
an insulating layer configured to electrically insulate the air flow sensor from a fluid in the air flow channel.
8. The fall detector as claimed in claim 7 , wherein the air flow sensor further includes:
a substrate, the substrate being patterned to provide an aperture to expose the bond pad to enable contact with the bond pad through the aperture.
9. The fall detector as claimed in claim 8 , wherein the electrically driven thermal element includes:
a heating element and a temperature sensor element disposed on the front side of the air flow sensor facing the air flow channel.
10. The fall detector as claimed in claim 5 , further including:
an alarm configured to be triggered by the processor when the processor determines that a fall has occurred.
11. A method in a fall detector of detecting falls of a user or an object to which the fall detector is attached, the method comprising:
with a thermal air flow sensor, which is disposed adjacent an air flow channel of the fall detector, measuring air flow along the air flow channel of the fall detector;
measuring accelerations of the fall detector with an accelerometer; and
with a processor,
estimating an orientation of the fall detector from the measurements from the accelerometer, estimating a vertical velocity from the measurements from the air flow sensor and the estimated orientation, estimating a change in altitude from the estimated vertical velocity, and determining whether a fail has occurred based on the estimated change in altitude.
12. The method as claimed in claim 11 , further including:
with the processor, triggering an alarm when the processor determines that the fall has occurred.
13. A fall detector comprising:
an accelerometer configured to measure orientation and accelerations;
an air flow sensor configured to measure air flow through a channel; and
a processor configured to:
with the orientation measurements from the accelerometer, identify air flow measurement components in a vertical direction,
from the air flow measurement components in the vertical direction, generate a vertical velocity profile indicating how the velocity changes over time,
from the accelerations measured by the accelerometer, generating an acceleration profile which indicates timing and magnitude of impacts, and
determining whether a fall has taken place from the vertical velocity profile and the acceleration profile.
14. The fall detector as claimed in claim 13 , further including:
an alarm configured to be triggered by the processor when the processor determines that a fall has occurred.