Presence detector and occupant support employing the same
An occupant support 20 augmented with a detection system for assessing the condition of an occupant includes first and second detectors 58, 62 for detecting presence of the occupant, an occupancy detector for determining if the occupant is occupying the occupant support and an analyzer for assessing whether a presence indication from each of the first and second detectors and an occupancy indication from the occupancy detector correspond to a satisfactory condition of the occupant or an unsatisfactory condition of the occupant. A presence detection system for determining the condition of a target comprises a first and second detectors for detecting presence of the target in first and second regions, and an analyzer for assessing whether presence indications established by the presence detectors correspond to a satisfactory condition of the target or an unsatisfactory condition of the target.
1. An occupant support augmented with a detection system for assessing the condition of an occupant comprising:
a first detector for detecting presence of the occupant;
a second detector spaced from the first detector for detecting presence of the occupant;
an occupancy detector for determining if the occupant is occupying the occupant support; and
an analyzer for assessing whether a presence indication from each of the first and second detectors and an occupancy indication from the occupancy detector correspond to a satisfactory condition of the occupant or an unsatisfactory condition of the occupant and, in the event the condition is unsatisfactory, responding to the unsatisfactory condition.
2. The occupant support of claim 1 wherein the first and second detectors are spaced by elevation.
3. The occupant support of claim 1 wherein the first and second detectors are mounted on the occupant support.
4. The occupant support of claim 1 wherein at least one of the first and second detectors is height adjustable.
5. The occupant support of claim 1 wherein occupancy detection is based on whether or not occupant weight is being borne by the occupant support.
6. The occupant support of claim 1 wherein occupancy detection is based on an output of an occupant position monitoring system.
7. The occupant support of claim 1 wherein non-occupancy of the occupant support is declared only if indication thereof persists for at least a minimum time interval.
8. The occupant support of claim 1 wherein at least one of the first and second detectors comprises a detector array.
9. The occupant support of claim 1 wherein the detectors are arranged to detect occupant presence in different planes.
10. The occupant support of claim 1 wherein the detectors detect presence by detecting motion.
11. The occupant support of claim 10 wherein indications of presence and absence are based on characteristics of the motion.
12. The occupant support of claim 1 wherein the presence detectors are motion detectors.
13. The occupant support of claim 12 wherein indications of presence and absence are based on characteristics of motion detected by the motion detectors.
14. The occupant support of claim 1 wherein the response to the unsatisfactory condition is an alarm.
15. The occupant support of claim 1 wherein the first detector is a high detector and the second detector is a low detector located lower than the first detector.
16. The occupant support of claim 15 wherein the high detector is located no higher than a prescribed height and the low detector is located lower than the high detector and at a height no higher than a specified height.
17. The occupant support of claim 16 wherein the prescribed height is the shortest height of 99% of a population sample.
18. The occupant support of claim 16 wherein the specified height is about 25 cm (approximately 10 inches) above floor level.
19. The occupant support of claim 15 wherein the condition assessment is based on rules set forth below in which “P” signifies a state of occupant presence and “A” indicates a state of occupant absence:
Is Occupant
State
State
Occupying the
Indication of
Indication of
Occupant
Condition
High Detector
Low Detector
Support?
Assessment
P
P
YES
Satisfactory
or Null
P
A
YES
Satisfactory
or Null
A
P
YES
Satisfactory
or Null
A
A
YES
Satisfactory
or Null
P
P
NO
Satisfactory
P
A
NO
Satisfactory
or Fault
A
P
NO
Unsatisfactory
A
A
NO
Satisfactory
or Fault or
Unsatisfactory.
20. The occupant support of claim 15 comprising an intermediate detector at an elevation intermediate the high and low detectors and wherein the condition assessment is based on rules set forth below in which “P” indicates a state of occupant presence and “A” indicates a state of occupant absence:
Is
State
State
State
Occupant
Indication
Indication
Indication
Occupying
of
of
of
the
High
Intermediate
Low
Occupant
Condition
Detector
Detector
Detector
Support?
Assessment
P
P
P
YES
Satisfactory
or Null
P
P
A
YES
Satisfactory
or Null
P
A
P
YES
Satisfactory
or Null
P
A
A
YES
Satisfactory
or Null
A
P
P
YES
Satisfactory
or Null
A
P
A
YES
Satisfactory
or Null
A
A
P
YES
Satisfactory
or Null
A
A
A
YES
Satisfactory
or Null
P
P
P
NO
Satisfactory
P
P
A
NO
Satisfactory
or Fault
P
A
P
NO
Satisfactory
or Fault
P
A
A
NO
Satisfactory
or Fault
A
P
P
NO
Unsatisfactory
A
P
A
NO
Satisfactory
or Fault
A
A
P
NO
Unsatisfactory
A
A
A
NO
Satisfactory
or Fault.
21. The occupant support of claim 15 comprising an intermediate detector at an elevation intermediate the low and high detectors and wherein the condition assessment when the occupant is not occupying the occupant support is based on rules set forth below in which “H” indicates that the state of the high detector has changed from present to absent, M indicates that the state of the intermediate detector has changed from present to absent, L indicates that the state of the low detector has changed from present to absent, and t 1 , t 2 and t 3 indicate the temporal order in which the states have changed from present to absent with t 3 being no earlier than t 2 and t 2 being no earlier than t 1 :
Condition
t1
t2
t3
Assessment
Interpretation
H
Unsatisfactory
FALL
M
Satisfactory
Fault
L
Satisfactory
Fault
H
M
Unsatisfactory
FALL
H
L
Satisfactory
Fault
M
H
Unsatisfactory
FALL
M
L
Satisfactory
Fault
L
H
Satisfactory
Fault
L
M
Satisfactory
fault
H
M
L
Unsatisfactory
FALL
H
L
M
Unsatisfactory
FALL
M
H
L
Satisfactory
fault
M
L
H
Satisfactory
fault
L
H
M
Satisfactory
fault
L
M
H
Satisfactory
fault.
22. The occupant support of claim 1 wherein the first and second detectors can each indicate a state of occupant presence or absence, and the condition assessment depends on a temporal relationship between a change in the state indication of the first detector and a change in the state indication of the second detector.
23. The occupant support of claim 22 wherein the unsatisfactory condition corresponds to the state indication of the first detector changing from present to absent prior to or without a change in the state indication of the second detector from present to absent.
24. The occupant support of claim 23 wherein the first detector is a relatively high elevation detector and the second detector is a relatively low elevation detector.
25. A method for assessing and responding to the condition of an occupant associated with an occupant support, comprising:
detecting presence of the occupant in a first region;
detecting presence of the occupant in a second region different from the first region;
determining if the occupant is occupying the occupant support; and
assessing, in response to the presence indications from each of the first and second regions and the occupancy determination, whether the condition of the occupant is satisfactory or unsatisfactory and, in the event the condition is unsatisfactory, responding to the unsatisfactory condition.
26. The method of claim 25 wherein the first and second regions are at different elevations.
27. The method of claim 25 wherein the occupancy determination is based on whether or not occupant weight is being borne by the occupant support.
28. The method of claim 25 wherein the occupancy determination is based on an output of an occupant position monitoring system.
29. The method of claim 25 wherein the determination of occupancy includes a time interval during which indication of non-occupancy is disregarded.
30. The method of claim 25 wherein the first and second regions are substantially planar.
31. The method of claim 25 wherein the steps of detecting presence in the first and second regions are steps of detecting motion in the first and second regions.
32. The method of claim 31 wherein the steps of detecting motion are steps of detecting characteristics of motion.
33. The method of claim 25 wherein the response to the unsatisfactory condition is issuance of an alarm.
34. The method of claim 25 wherein the first region is a high region no higher than a prescribed height and the second region is a low region lower than the high region and no higher than a specified height.
35. The method of claim 34 wherein the prescribed height is the shortest height of 99% of a population sample.
36. The method of claim 34 wherein the specified height is about 25 cm (approximately 10 inches) above floor level.
37. The method of claim 34 wherein the condition assessment is based on rules set forth below in which “p” signifies a state of occupant presence and “A” indicates a state of occupant absence:
Is Occupant
State
State
Occupying the
Indication of
Indication of
Occupant
Condition
High Region
Low Region
Support?
Assessment
P
P
YES
Satisfactory
or Null
P
A
YES
Satisfactory
or Null
A
P
YES
Satisfactory
or Null
A
A
YES
Satisfactory
or Null
P
P
NO
Satisfactory
P
A
NO
Satisfactory
or Fault
A
P
NO
Unsatisfactory
A
A
NO
Satisfactory
or Fault or
Unsatisfactory.
38. The method of claim 34 comprising an intermediate detector at an elevation intermediate the high and low detectors and wherein the condition assessment is based on rules set forth below in which “P” indicates a state of occupant presence and “A” indicates a state of occupant absence:
Is
State
State
Occupant
Indication
Indication
State
Weight
of
of
Indication
on the
High
Intermediate
of
Occupant
Condition
Region
Region
Low Region
Support?
Assessment
P
P
P
YES
Satisfactory
or Null
P
P
A
YES
Satisfactory
or Null
P
A
P
YES
Satisfactory
or Null
P
A
A
YES
Satisfactory
or Null
A
P
P
YES
Satisfactory
or Null
A
P
A
YES
Satisfactory
or Null
A
A
P
YES
Satisfactory
or Null
A
A
A
YES
Satisfactory
or Null
P
P
P
NO
Satisfactory
P
P
A
NO
Satisfactory
or Fault
P
A
P
NO
Satisfactory
or Fault
P
A
A
NO
Satisfactory
or Fault
A
P
P
NO
Unsatisfactory
A
P
A
NO
Satisfactory
or Fault
A
A
P
NO
Unsatisfactory
A
A
A
NO
Satisfactory
or Fault.
39. The method of claim 34 comprising the step of detecting presence of the occupant in an intermediate region at an elevation intermediate the low and high regions and wherein the condition assessment when the occupant is not occupying the occupant support is based on rules set forth below in which “H” indicates that the state of the high detector has changed from present to absent, M indicates that the state of the intermediate detector has changed from present to absent, L indicates that the state of the low detector has changed from present to absent, and t 1 , t 2 and t 3 indicate the temporal order in which the states have changed from present to absent with t 3 being no earlier than t 2 and t 2 being no earlier than t 1 :
Condition
t1
t2
t3
Assessment
Interpretation
H
Unsatisfactory
FALL
M
Satisfactory
Fault
L
Satisfactory
Fault
H
M
Unsatisfactory
FALL
H
L
Satisfactory
Fault
M
H
Unsatisfactory
FALL
M
L
Satisfactory
Fault
L
H
Satisfactory
Fault
L
M
Satisfactory
fault
H
M
L
Unsatisfactory
FALL
H
L
M
Unsatisfactory
FALL
M
H
L
Satisfactory
fault
M
L
H
Satisfactory
fault
L
H
M
Satisfactory
fault
L
M
H
Satisfactory
fault.
40. The method of claim 25 wherein the steps of detecting in the first and second regions each result in detecting presence or absence of the occupant, and the condition assessment depends on a temporal relationship between a change in the result of detecting in the first region and a change in the result of detecting in the second region.
41. The method of claim 40 wherein the unsatisfactory condition corresponds to a change in the result from the first region from present to absent occurring prior to or without a change in the result from the second region from present to absent.
42. The method of claim 41 wherein the first region is a relatively high elevation region and the second detector is a relatively low elevation region.
43. A presence detection system for determining the condition of a target, comprising:
a first detector for detecting presence of the target in a first region;
a second detector for detecting presence of the target in a second region;
an analyzer for assessing whether presence indications established by the presence detectors correspond to a satisfactory condition of the target or an unsatisfactory condition of the target and, in the event the condition is unsatisfactory, responding to the unsatisfactory condition.
44. The presence detection system of claim 43 wherein the regions are substantially planar.
45. The presence detection system of claim 43 wherein the regions are three dimensional.
46. A method of detecting and responding to the condition of a target, comprising:
monitoring for presence of the target in a first region;
monitoring for presence of the target in a second region;
assessing whether presence indications established by the presence monitoring correspond to a satisfactory condition of the target or an unsatisfactory condition of the target and, in the event the condition is unsatisfactory, responding to the unsatisfactory condition.
47. The method of claim 46 wherein the regions are substantially planar.
48. The method of claim 46 wherein the regions are three dimensional.