Method and device for fall prevention and detection
First Claim
1. A method of monitoring an object with respect to a potential fall condition, comprising:
- observing a detection area with an optical detector;
determining, based on at least one image of the detection area, that the object is in an upright condition in the detection area;
bydetermining an angle between the object and a vertical direction and that the angle is below 20 degrees;
bytransforming foot image coordinates (uf, vf) of a foot portion of the object into foot room coordinates (Xf, Yf=0, Zf);
adding a length Δ
Y to a vertical coordinate of the foot room coordinates;
transforming at least the vertical coordinate to form top image coordinates (uh, Vh), whereby the vertical direction is given by a vector, between the foot image coordinates (uf, Vt) and the top image coordinates (uh, vh); and
determining an angle between said vector and the object;
waiting for a predetermined time period; and
emitting an alarm after said predetermined time period.
3 Assignments
0 Petitions
Accused Products
Abstract
Method and device for fall prevention and detection, specially for the elderly care based on digital image analysis using an intelligent optical sensor. The fall detection is divided into two main steps; finding the person on the floor, and examining the way in which the person ended up on the floor. The first step is further divided into algorithms investigating the percentage share of the body on the floor, the inclination of the body and the apparent length of the person. The second step includes algorithms examining the velocity and acceleration of the person. When the first step indicates that the person is on the floor, data for a time period of a few seconds before and after the indication is analysed in the second step. If this indicates fall, a countdown state is initiated in order to reduce the risk of false alarms, before sending an alarm. The fall prevention is also divided into two main steps; identifying a person entering a bed, and identifying the person leaving the bed to end up standing beside it. The second step is again further divided into algorithms investigating the surface area of on or more objects in an image, the inclination and the apparent length of these objects. When the second step indicates that a person is in an upright condition, a countdown state is initiated in order to allow for the person to return to the bed.
25 Citations
38 Claims
-
1. A method of monitoring an object with respect to a potential fall condition, comprising:
-
observing a detection area with an optical detector; determining, based on at least one image of the detection area, that the object is in an upright condition in the detection area;
bydetermining an angle between the object and a vertical direction and that the angle is below 20 degrees;
bytransforming foot image coordinates (uf, vf) of a foot portion of the object into foot room coordinates (Xf, Yf=0, Zf); adding a length Δ
Y to a vertical coordinate of the foot room coordinates;transforming at least the vertical coordinate to form top image coordinates (uh, Vh), whereby the vertical direction is given by a vector, between the foot image coordinates (uf, Vt) and the top image coordinates (uh, vh); and determining an angle between said vector and the object; waiting for a predetermined time period; and emitting an alarm after said predetermined time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. The method of monitoring an object with respect to a potential fall condition, comprising:
-
observing a detection area with an optical detector; defining a room height limit in room coordinates; transforming said room height limit into an image height limit in image coordinates; forming a foreground image by calculating a difference between a current image and a background image; deriving a number of foreground elements from the foreground image, said number representing the foreground elements that are located below the image height limit in the foreground image; determining based on at least one image of the detection area, that the object is in an upright condition in the detection area;
bydetermining that said number exceeds a predetermined value, waiting for a predetermined time period; and
emitting an alarm after said predetermined time period.
-
-
10. A device for monitoring an object with regard to a potential fall condition, comprising:
-
a detector for observing a detection area; a determination device for determining, based on at least one image from the detector, that the object is in an upright condition in the detection area;
comprisinga height limit calculation device for defining a room height limit in room coordinates;
transforming said room height limit into an image height limit in image coordinates;
forming a foreground image by calculating a difference between a current image and a background image;
deriving a number of foreground elements from the foreground image, said number representing the foreground elements that are located below the image height limit in the foreground image;
wherein determining that the object is in the upright condition comprises determining that said number exceeds a predetermined value, andan alarm device for emitting an alarm a predetermined time period after a determination of an upright condition by the determination device. - View Dependent Claims (11, 12, 13, 14)
-
-
15. A method of monitoring an object with regard to a fall condition, comprising:
-
observing a detection area with an optical detector; determining, based on at least one image of the detection area, that the object is lying on a floor in the detection area;
bycalculating a foreground image, which is the difference between a current image and a predetermined background image, calculating the ratio of the foreground image that is present on the floor of the detection area, and determining that the ratio exceeds a predetermined threshold ratio; waiting for a predetermined time period; and emitting an alarm after said predetermined time period. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
-
-
23. A method of monitoring an object with regard a fall condition, comprising
observing a detection area with an optical detector; -
determining, based on at least one image of the detection area, that the object is lying on a floor in the detection area;
byderiving an image sequence for at least a time period preceding the determination that the object is lying on the floor; and analysing the derived image sequence for high velocities and/or negative accelerations; wherein a subsequent step for identifying the fall condition comprises determining that the velocity is above a predetermined value and/or the acceleration is below a negative value; and emitting an alarm after a predetermined time period. - View Dependent Claims (24, 25, 26, 27)
-
-
28. A method of monitoring an object with regard a fall condition, comprising
observing a detection area with an optical detector; -
determining, based on at least one image of the detection area, that the object is lying on a floor in the detection area;
byforming a foreground image by calculating a difference between a current image and a previous image; and deriving a number of foreground elements from the foreground image;
wherein a subsequent step for identifying the fall condition comprises determining that the number of foreground elements exceeds a foreground number value; andemitting an alarm after a predetermined time period. - View Dependent Claims (29, 30, 31)
-
-
32. A device for monitoring an object with regard to a fall condition, comprising:
-
a detector for observing a detection area; a determination device for determining, based on at least one image from the detector, that the object is lying on a floor in the detection area;
said determination device further comprisesa foreground calculation device for calculating a foreground image, which is the difference between a current image and a predetermined background image; and
calculating the ratio of the foreground image that is present on the floor of the detection area and the total foreground image;
wherein determining that the object is lying on the floor comprises determining that the ratio exceeds a predetermined threshold ratio, andan alarm device for emitting an alarm a predetermined time period after a determination that the object is lying on the floor by the determination device. - View Dependent Claims (33, 34, 35, 36, 37, 38)
-
Specification