The subject matter described herein relates to articulable supports, such as hospital beds, and particularly to a support whose articulation depends at least in part on anthropometric considerations.
Health care facilities use articulated beds, i.e. beds with segments connected together at joints so that the angular orientation of the segments and/or the positions of the segments can be changed. These beds, or the jointed segments thereof, are customarily referred to as “articulating” or “articulable”. The term “articulation” is also routinely used to refer to the motion of the segments, for example rotational motion of the segments about the joint axes and translational motion of the segments.
Articulation of the bed can cause the occupant of the bed to migrate toward the foot end of the bed. The need to reposition the migrated occupant adds to the workload of the caregiver staff. Moreover, the physical demands of repositioning the occupant can cause injury to the caregiver. The articulation can also cause chafing and abrasion of the occupant's skin.
It is, therefore, desirable to regulate the articulation in a way that resists the tendency of the occupant to migrate toward the foot of the bed.
An occupant support system for supporting an occupant comprises a frame, an articulable assembly which includes an upper body section, and a motion control system arranged to rotate the upper body section by an amount Au relative to the frame, to translate the upper body section along the frame by an amount ΔCS, and to translate the upper body section by an amount ΔBS in a direction parallel to the upper body section. Both ΔBS and ΔCS are a function of Δα.
The foregoing and other features of the occupant support described herein will become more apparent from the following detailed description and the accompanying drawings.
Referring to
The bed also includes an articulable assembly 52 comprising three principal sections: an upper body section 54, a seat section 56, and a leg section 58. The leg section comprises a thigh section 60 and a calf section 62.
The upper body section 54 includes an upper body frame 70 comprising upper body lateral rails (i.e. left and right rails 72) non-movably connected to an upper beam 74 and a lower beam 76. The lateral rails are also connected to a first carriage C1 at pivot joints that define a first pivot axis P1. The carriage spans laterally between the rails 40 of the upper frame and includes left and right trolleys T1 for translatably connecting the carriage to the rails 40.
Compression links 78 are connected to the upper body rails 72 at pivot joints that define a second pivot axis P2. The other end of each compression link is connected to a second carriage C2 at pivot joints that define a third pivot axis P3. Trolleys T2 translatably connect the second carriage to the upper frame rails 40. Trolleys T3 and T4 translatably connect an upper body deck panel 82 to the upper body rails 72.
The seat section 56 of the bed includes a seat deck panel 84 translatably connected to the upper frame rails 40 by way of connectors 86 and trolleys T5. Trolleys T5, unlike the other trolleys referred to herein, ride along the outboard side of each upper frame rail 40 rather than along the inboard side.
The thigh section 60 includes a thigh section frame 90 comprising lateral beams (i.e. left and right beams 92) and a lower beam 94 extending laterally between the left and right beams. In the illustrated construction, the lateral beams are welded to the lower beam. The upper ends of the lateral beams 92 are connected to a third carriage C3 at pivot joints that define a fourth pivot axis P4. A sixth trolley T6 translatably connects the carriage C3 to the upper frame rails 40. A thigh deck panel 96 is nonmovably connected to the thigh frame 90
The calf section 62 includes a calf section frame 100 comprising lateral beams (i.e. left and right beams 102) an upper beam 104 and a lower beam 106. The upper and lower beams extend laterally between the left and right beams. In the illustrated construction, the lateral beams 102 and lower beam 106 are a single part, and the upper beam is a separate part welded to lateral beams 102 near their upper ends. The upper end of each lateral beam 102 is connected to the lower end of the corresponding thigh beams 92 at a pivot joint. The pivot joints define a fifth pivot axis P5. A link 108 is non-pivotably connected to each beam 102 near the lower end of the beam. The other end of each link 108 is connected to a seventh trolley T7 at a pivot joint, the pivot joints defining a sixth pivot axis P6. A calf deck panel 112 is non-movably secured to the calf frame 100. A mattress retainer 116 spans laterally across the calf deck.
Each section of the illustrated articulable assembly 52 is capable of at least one of several modes of motion. The upper body section 54 is translatable along the upper frame rails 40 in a positive or headward direction (toward the head end of the bed) and a negative or footward direction (toward the foot end of the bed). The upper body frame 70 and deck 82 are also pivotable about axis P1 so that the upper body deck forms a variable angle α with the upper frame rails. Rotation about axis P1 that pivots the upper body section away from upper frame 32 and increases α is positive rotation whereas rotation that pivots the upper body section toward the upper body frame and decreases α is negative rotation. The upper body deck 82 is also slidable relative to the frame 70 in a direction parallel to the existing orientation of the upper body section. This motion is referred to herein as “parallel translation” to distinguish it from translation of the upper body section along the upper frame rails 40. Positive parallel translation is translation toward the head or upper end of the upper body frame whereas negative parallel translation is translation toward the foot or lower end of the upper body frame.
The seat section 56 is capable of headward and footward translation along the upper frame rails 40.
The leg section 58, which comprises the thigh and calf sections 60, 62, is headwardly (positively) and footwardly (negatively) translatable along the rails 40. The thigh and calf sections are also individually pivotable about pivot axes P4 and P6 respectively. Rotations that pivot the thigh and calf sections away from the upper frame and decrease the angle β between the thigh and calf decks are positive rotations. Rotations that pivot the thigh and calf sections toward the upper frame and increase the angle β between the thigh and calf decks are negative rotations.
Collectively, deck panels 82, 84, 96, 112 define a deck 120. As seen schematically in
The bed also includes a suite of actuators. A first actuator A1 extends from upper frame cross member 46 to the second carriage C2. A second actuator A2 extends from the same cross member to the first carriage C1. Equal extension or retraction of actuators A1 and A2 moves carriages C2 and C1 to translate the upper body section 54 headwardly or footwardly respectively. Unequal extension or retraction (including extension of one actuator and retraction of the other) will cause, in addition to translation, rotation of the upper body section about axis P1. The limit case in which the extension or retraction is unequal because one of the actuators A1, A2 is not extended or retracted at all will cause rotation about P1 but no translation.
A third actuator A3 is secured at its lower end to the lower beam 76 of the upper body frame and at its upper end to the upper body deck 82. Extension of the third actuator causes positive parallel translation of the upper body section deck; retraction of actuator A3 causes negative parallel translation.
A fourth actuator A4 is secured at its lower end to the cross member 46 that hosts the lower ends of actuators A1 and A2 and at its upper end to carriage C3. Extension or retraction of actuator A4 moves carriage C3. Trolleys T7 move the same distance as the trolleys T6 to which carriage C3 is attached. As a result the leg section 58 translates headwardly or footwardly with no change in the angular orientation of the thigh and calf frames and decks.
A fifth actuator A5 is secured at its upper end to carriage C3 and at its lower end to a bracket 124 projecting from the thigh section frame. Extension of actuator A5 rotates the thigh frame in the positive direction about axis P4. Because the thigh and calf frames are connected at the pivot joints that define axis P5, the extension of the actuator A5 also rotates the calf frame in a positive direction about axis P6, reducing the angle β (
The various actuators govern the motions of all the sections except for the seat section 56. The seat section translates headwardly and footwardly in response to the longitudinal stretching or relaxation of the mattress that takes place as a consequence of movement of the other sections 54, 60, 62. As the mattress stretches and relaxes, it drags the seat deck panel causing the seat section to translate.
The bed also includes a processor 126 indicated schematically in
Collectively, the control laws processed by the processor 126, and the kinematic linkages including the actuators, comprise a motion control system. The motion control system is configured to control the motion of the articulating assembly 52 based on anthropometric considerations. Of particular interest is an occupant's greater trochanter 130, which is the bony lateral protrusion of the proximal end of the femur as seen in
The motion control system controls the motion of the articulating sections as the sections move between a starting configuration at which the occupant's trochanter is at a starting spatial location relative to the articulable assembly and an end configuration at which the occupant's trochanter is at an ending spatial location. In particular, in order to resist occupant migration toward the foot of the bed, the motion control system controls the motion such that upon return of the bed to the starting configuration the occupant's trochanter point is at a spatial location substantially the same as the starting spatial location. In the limit, the occupant's trochanter remains at substantially the same spatial location during the motion from the starting configuration to the end configuration and back again. Such a result is not achieved with pre-existing beds because of occupant migration that occurs as a result of bed articulation.
A mode of articulation that resists the tendency for the occupant to migrate toward the foot of the bed may be understood by considering the anthropometric dimensions BANTHRO and CANTHRO seen in
The scheduled parallel translation ΔBS is determined from the relationship of
ΔBS=|(BS)1−(BS)2| (1)
The scheduled translation ΔCS of the upper body section is determined from the relationship of
ΔCS=|(CS)1−(CS)2| (2)
To summarize the foregoing, if the upper body section is at an initial orientation α1 and it is desired to change the orientation to α2, the upper body deck panel will be commanded to undergo a positive parallel translation of ΔBS and the upper body section will be commanded to undergo a positive (headward) translation of ΔCS. It may also be desirable to adjust the angle β between the thigh and calf sections to provide appropriate patient comfort including heel pressure relief.
Applicants have determined that dimensions BANTHRO and CANTHRO can be satisfactorily estimated as a function of an occupant's weight to height ratio W/H expressed in pounds per inch as shown in
In general, different occupants will exhibit different values of BANTHRO and CANTHRO and will therefore require different translations ΔCS and parallel translations ΔBS to experience satisfactory anthropometric performance when the upper body section is rotated from α1 to α2. In other words, the anthropometric values BANTHRO and CANTHRO and the anthropometric ratio BANTHRO/CANTHRO are not the same for all occupants, and therefore the values ΔBS and ΔCS are also not the same for all occupants. However the mechanical components required to provide occupant specific customization of ΔBS and ΔCS will be more complex, bulkier, heavier, more expensive and less reliable than those for providing fixed values of ΔBS and ΔCS (and a fixed value of the ratio ΔBS/ΔCS) for any given initial value of a. Good reliability is highly desirable when the motion control system is designed to provide a Cardio-Pulmonary Resuscitation (CPR) feature which places the articulable frame panels in a level and flat configuration in response to a single, simple input, e.g. pressure exerted on a push button or a pedal. Therefore, it may be advisable to arrange the kinematics to provide a constant ΔBS/ΔCS ratio or at least a ΔBS/ΔCS ratio that is fixed for any given initial value of α, thereby achieving the best possible reliability of the CPR feature in return for some sacrifice in anthropometric performance.
Referring to
A simple implementation of the foregoing involves developing a profile of a “standard occupant” using anthropometric statistics, preferably statistics representative of a target population of individuals. The anthropometric characteristics of the standard occupant are used by a designer to design the motion control system so that the system governs the movement of the articulable frame elements (the translation of the upper body section, parallel translation of the upper body deck panel and any compensatory translation of the leg section) in a way that is anthropometrically satisfactory for the standard occupant. The motions thus delivered by the motion control system are neither occupant specific nor “field configurable” by a typical caregiver or occupant. In other words, there is only a single functional relationship between the motion delivered by the motion control system and the anthropometric information used by the designer.
Such a “one size fits all” approach will, of course, be suboptimal for most occupants, but will nevertheless be superior to nonanthropometric designs.
A more sophisticated approach allows a user, typically a caregiver in a health care setting, to manually provide anthropometric inputs to the controller. For example, as seen in
B
ANTHRO-FEMALE=0.8994(W/H)+1.3385
C
ANTHRO-FEMALE=0.6729(W/H)+3.9445
B
ANTHRO-MALE=0.6778(W/H)+1.9347
C
ANTHRO-MALE=0.7433(W/H)+3.2258
Applicants have also observed that the data samples upon which the above equations are based exhibit greater scatter for occupants having a higher W/H ratio and less scatter for occupants having a low W/H ratio. Accordingly, it may be desirable to use two sets of equations, one for occupants whose W/H exceeds 3.5 and another for occupants whose W/H is no greater than 3.5, as set forth below:
B
ANTHRO-FEMALE=0.66(W/H)+1.80 (W/H 3.5)
C
ANTHRO-FEMALE=0.55(W/H)+4.13 (W/H 3.5)
B
ANTHRO-MALE=0.48(W/H)+2.21 (W/H 3.5)
C
ANTHRO-MALE=0.63(W/H)+3.27 (W/H 3.5)
B
ANTHRO-FEMALE=0.80(W/H)+1.88 (W/H>3.5)
C
ANTHRO-FEMALE=0.42(W/H)+5.39 (W/H>3.5)
B
ANTHRO-MALE=0.27(W/H)+4.25 (W/H>3.5)
C
ANTHRO-MALE=0.26(W/H)+5.99 (W/H>3.5)
It is evident that the exact relationships can be chosen based on any data and curve fitting accuracy satisfactory to the designer.
As already noted, the control laws can be written to account for other inter-individual and intra-individual characteristics, and the user interface can be correspondingly designed to accept relevant inputs.
A variant on the immediately preceding approach involves control laws that use more subjective indicia of an occupant's anthropometric characteristics (and an associated user interface (
Local or non-local resources can be used to automatically acquire some or all of the input data used by the control laws. For example, the relevant data might be on record in a non-local database. If so, the data can be conveyed to the bed through a facility communication network. Alternatively, systems on board the bed can be used. For example, patient weight is readily available on beds designed with a built-in scale and an occupant's height can be determined with pressure sensors installed in or on the mattress. Hybrid approaches using combinations of data acquired manually or automatically from local or remote sources are also envisioned.
With the structure and function of the bed having now been described, certain variations can now be better appreciated.
Referring to
Although the disclosed bed includes three principal sections 54, 56 and 58, occupant migration toward the foot of the bed can, in principle, be mitigated without the use of the seat section 56, i.e. with only the upper body section 54 and, if it is desired to provide the above described compensatory translation, the translatable leg section 58. It will be necessary, of course, to ensure that the mattress receives adequate vertical support despite the absence of the illustrated seat section.
As is evident in
The leg section 58 need not be articulable, especially if a motion control system capable of delivering occupant customized amounts of ΔBS and ΔCS is used. However the absence of leg section translatability will introduce anthropometric compromises (in a fixed ΔBS/ΔCS ratio system) and the inability to adjust the angle β will compromise the ability to enhance occupant comfort and provide heel pressure relief.
The calf section 62 could also be constructed with a calf deck panel similar to the upper body deck panel 82 and able to undergo a similar parallel translation.
The reader should also appreciate that many kinematic arrangements other than as described herein may be used and may be more commercially attractive. For example, the illustrated bed includes three actuators A1, A2, A3 for controlling motions of the upper body frame. The multiple actuators are desirable in a prototype or experimental bed to allow maximum flexibility of articulation during testing and development. However it is envisioned that beds produced for commercial sale will include fewer actuators for the upper body section. For example, as seen in
The mattress 122 illustrated in
The mattress may be an inflatable mattress, a non-inflatable mattress or may have both inflatable and non-inflatable components.
The relationship of equation (1) for determining ΔBS presupposes the use of a mattress of known thickness and elasticity. However the use of alternative mattresses having different properties can also be accommodated. For example, a user interface device can include provisions for indicating which of two or more candidate mattresses having known properties is being used (e.g. the user would select between the model 2000, 2200 and 2500 mattresses). The processor's memory would include mattress specific adjustments (e.g. to the relationships of
Although this disclosure refers to specific embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the subject matter set forth in the accompanying claims.
This application claims priority to U.S. patent application Ser. No. 12/618,256 entitled “Anthropometrically Governed Occupant Support” filed on Nov. 13, 2009, which claims priority to Provisional Patent Application 61/115,374, Entitled “Anthropometrically Governed Occupant Support” filed on Nov. 17, 2008, the disclosures of both of which are expressly incorporated by reference herein.
Number | Date | Country | |
---|---|---|---|
61115374 | Nov 2008 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 12618256 | Nov 2009 | US |
Child | 14024858 | US |