Abstract:
The present invention relates to personnel lifts for positioning a subject relative to a work space. Lifts of the invention may include a base, a mechanical positioner, a platform, and a controller. Controllers suitable for use with lifts of the invention are preferably capable of directing continuous, intermittent, periodic, or sporadic adjustment of the subject&#39;s position without requiring the subject to break visual or tactile contact with the work space.

Description:
RELATED APPLICATION  
       [0001]     This application claims priority to U.S. Provisional Patent Application Ser. No. 60/645,320, filed Jan. 19, 2005 and entitled “MULTI-DIRECTIONAL PERSONNEL LIFT,” the contents of which are hereby incorporated in their entirety by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention is related to a device for positioning a person relative to a work space.  
       BACKGROUND OF THE INVENTION  
       [0003]     In certain work situations it is critically important for those performing a task to possess the ability to optimize hand placement and to maintain the best line of sight during a particular step in the process. Work performed over long periods of time, especially during times when delicate, tedious procedures are involved, can require several steps, and the need for several different positions and ergonomic relationships. As one example, an optimal ergonomic relationship between a doctor and his/her patient is particularly critical in situations such as conducting surgical procedures within an abdominal cavity.  
         [0004]     The achievement and maintenance of the optimal ergonomic relationship between one performing work and a work space can reduce the time, energy, effort and cost of performing a work function. It can also reduce the possibility of acute workplace injuries though improvisation, such as using makeshift devices such as stools, ladders, crates, buckets, and could reduce the occurrence of chronic injuries due to improper body, neck, hand, and head placement over extended periods of time.  
         [0005]     In healthcare, the ergonomic relationship a surgeon and a patient can directly affect the difficulty, time, safety, expense, and outcome of a surgical procedure. Where the relationship between the patient and health care worker is less than optimal, patient health may be adversely affected by resulting trauma to tissues, increased time under anesthesia, exposure. The overall quality of repairs to vital organs, nerves and tissues may suffer.  
         [0006]     State of art in the industrial workplace involves adjustable lifts, platforms and hoists for parts, sub-assemblies, and completed components. Examples include hydraulic motorcycle lifts, rotary tables, automotive hoists, hydraulic platforms and tables. State of the art in the healthcare field would include operating and exam tables, hydraulic lifting devices, hoists, cranes, and certain positioning devices. In these cases, it is the work space that is moved, not the subject who performs a task in the work space.  
       SUMMARY OF THE INVENTION  
       [0007]     In accordance with teachings of the present invention, a personnel lift is provided for positioning a worker relative to a work space. A lift of the invention may include a base and a platform and may be configured to accommodate one or more people. In one aspect of the inventions the platform is movable in one, two, or three dimensions and suitable for holding a surgeon or other medical professional during a health-related procedure. For example, in some non-limiting embodiments, the invention provides a lift for positioning and conveying a health care worker in and around a patient or surgical field. More specifically, a lift may be configured to comfortably and ergonomically hold a surgeon in a desired position during a bariatric procedure.  
         [0008]     The weight of subjects on the lift or other loads may be counter-balanced by the mass of the lift itself. In some embodiments, a lift may include counter-balancing weights, which may be positioned in one or more locations in or on the lift. In some embodiments, the lift may be reversibly or permanently anchored to the surface on which it rests (e.g. the floor). Lifts may also be reversibly or permanently anchored to a wall or ceiling. Reversible anchors may include any type of suction devices, bolts, or quick releases. Lifts of the invention may also be reversibly or permanently attached to an operating table. For example, in some embodiments, a lift of the invention includes or is integrated into an operating table. In such embodiments, the subject on the lift (e.g. the surgeon) is moved relative to the work space (e.g. operating field), but the work space is not moved relative to the surroundings (e.g. the operating room).  
         [0009]     Lifts of the invention may include a mechanical positioner capable of moving the platform in one, two, or three dimensions. The mechanical positioner may include a power supply, a motor, a scissor truss, a piston, a threaded member, a jack, a gear, a belt, a clutch, a rail, a track, a spring, a pump, a bladder, a drive wheel, a drive ball, casters, a conveyor belt, and combinations thereof. Lifts of the invention may include a controller operably linked to a mechanical positioner to control the direction and degree of movement of the platform. The controller may be actuated while allowing the subject to maintain visual and/or tactile contact with the work space. This may be particularly useful in the medical aspects of the present invention, where loss of visual or tactile contact with the patient may compromise the efficacy or safety of the procedure. By contrast, hand-operated controls may increase the risk of infection and preclude simultaneously executing a medical procedure and adjusting the lift&#39;s position. In some embodiments, the controls may be actuated by the subject, e.g. the surgeon. In some embodiments, the controls may be actuated by an assistant. In such embodiments, the assistant may or may not be on the lift when actuating the controls.  
         [0010]     Controllers suitable for use in lifts of the invention include any type of mechanical or electrical apparatus capable of receiving instructions from a subject and selectively activating the mechanical positioner such that the subject is moved to the instructed location. Controllers of the invention may be active continuously, intermittently, periodically, or upon demand. In some embodiments, the controller may be retracted or covered to prevent inadvertent activation when not in use. In one non-limiting example, foot-operated or touch-sensitive controls on the surface of a platform may be covered or locked so that further contact does not result in undesired or inadvertent platform movement.  
         [0011]     Platforms of the invention may be of any size or shape. Possible platform shapes include any type of regular or irregular two-or three dimensional shape. For example, platforms may be configured in the shape of any type of regular or irregular polygon (when viewed from above) including, without limitation, a triangle, any type of parallelogram, and any type of curvilinear shape. According to some embodiments of the invention, platforms may be generally rectangular and have a length of from about nineteen inches to about thirty-six inches and a width of from about thirty inches to about forty-eight inches. In some embodiments, the platform preferably has a length of twenty-four inches and a width of about thirty-six inches.  
         [0012]     Lifts of the invention may be configured to raise one or more subjects any desired distance from the surface on which the lift rests or any other reference point. In some non-limiting embodiments, lifts of the invention are capable of raising a subject from about six inches to about ninety-six inches from the surface on which the lift rests. It may be desirable, for certain embodiments, to configure the lift to raise the subject 6″-18″, 19″-36″, 37″ to 60″, or 61″ TO 96″ from the surface on which the lift rests. In addition, lifts of the invention may include one or more platforms, each of which may be independently or coordinately controlled.  
         [0013]     Lifts according to the present invention may also include a tilting platform with any number of desired or required supports, pads, and harnesses to put the subject at ease while performing a task in the work space. For example, each platform of the invention may include chest bolsters, hip bolsters, thigh bolsters, and shin/calf bolsters that may or may not completely encircle the body part supported.  
         [0014]     One of ordinary skill in the art will recognize that lifts of the invention may be useful in other contexts including, automotive repairs, painting, sculpturing, household repairs, and manufacturing. In addition, lifts of the present invention may be used to position a subject relative to a work space such that the work space is above, level with or below the subject&#39;s center of mass.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     A more complete and thorough understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:  
         [0016]      FIG. 1A  is a schematic drawing in elevation showing a lift of the invention in its home position;  
         [0017]      FIG. 1B  is a schematic drawing in elevation showing a lift of the invention in an elevated position;  
         [0018]      FIG. 1C  is a schematic drawing showing a plan view of the platform of the lift shown in  FIGS. 1A and 1B ;  
         [0019]      FIG. 2A  is a schematic drawing in elevation showing a lift of the invention in its home position;  
         [0020]      FIG. 2B  is a schematic drawing in elevation showing a lift of the invention in an elevated position;  
         [0021]      FIG. 2C  is a schematic drawing showing a plan view of the platform of the lift shown in  FIGS. 2A and 2B ;  
         [0022]      FIG. 3A  is a schematic drawing in elevation showing a lift of the invention in its home position;  
         [0023]      FIG. 3B  is a schematic drawing showing an end view of the lift shown in  FIG. 3A ;  
         [0024]      FIG. 3C  is a schematic drawing in elevation showing a lift of the invention in an elevated position;  
         [0025]      FIG. 3D  is a schematic drawing showing a plan view of the platform of the lift shown in  FIGS. 3A, 3B  and  3 C;  
         [0026]      FIG. 4A  is a schematic drawing in elevation showing a lift of the invention in its home position;  
         [0027]      FIG. 4B  is a schematic drawing in elevation showing a lift of the invention in an elevated position;  
         [0028]      FIG. 4C  is a schematic drawing showing a plan view of the platform of the lift shown in  FIGS. 4A and 4B ;  
         [0029]      FIG. 5A  is a schematic drawing in elevation showing a lift of the invention in its home position;  
         [0030]      FIG. 5B  is a schematic drawing in elevation showing a lift of the invention in an elevated position;  
         [0031]      FIG. 5C  is a schematic drawing showing a plan view of the lift shown in  FIGS. 5A and 5B ;  
         [0032]      FIG. 6A  is a schematic drawing of a cross-section of corner of a lift of the invention in its home position;  
         [0033]      FIG. 6B  is a schematic drawing showing an isometric view of a lift of the invention in its home position;  
         [0034]      FIG. 6C  is a schematic drawing showing an isometric view of a lift of the invention in its elevated position;  
         [0035]      FIG. 7A  is a schematic drawing of a cross-section of corner of a lift of the invention in its home position;  
         [0036]      FIG. 7B  is a schematic drawing showing an isometric view of a lift of the invention in its home position;  
         [0037]      FIG. 7C  is a schematic drawing showing an isometric view of a lift of the invention in a partially elevated position;  
         [0038]      FIG. 7D  is a schematic drawing showing an isometric view of a lift of the invention in a partially elevated position;  
         [0039]      FIG. 7E  is a schematic drawing showing an isometric view of a lift of the invention in its fully elevated position;  
         [0040]      FIG. 8A  is a schematic drawing in elevation showing a lift of the invention in its home position;  
         [0041]      FIG. 8B  is a schematic drawing in elevation showing a lift of the invention in an elevated position;  
         [0042]      FIG. 8C  is a schematic drawing showing a plan view of the lift shown in  FIG. 8B ;  
         [0043]      FIG. 8D  is a schematic drawing showing an isometric view of the lift shown in  FIGS. 8B and 8C ;  
         [0044]      FIG. 9  is a schematic drawing showing an isometric view of a lift of the invention in an elevated position;  
         [0045]      FIG. 10A  is a schematic drawing in elevation showing a lift of the invention in its home position;  
         [0046]      FIG. 10B  is a schematic drawing in elevation showing a lift of the invention in an elevated position;  
         [0047]      FIG. 11A  is a schematic drawing showing an isometric view of a lift of the invention in its start position;  
         [0048]      FIG. 11B  is a schematic drawing showing an isometric view of the lift shown in  FIG. 11A  in its elevated position;  
         [0049]      FIG. 11C  is a schematic drawing showing an isometric view of the lift shown in  FIG. 11B  in a laterally-shifted position;  
         [0050]      FIG. 11D  is a schematic drawing showing an isometric view of the lift shown in  FIG. 11C  in a forward-shifted position;  
         [0051]      FIG. 11E  is a schematic drawing showing a plan view of the lift shown in  FIG. 11A  in a laterally-shifted, forward-shifted position;  
         [0052]      FIG. 12A  is a schematic drawing showing an isometric view of a lift of the invention in its start position;  
         [0053]      FIG. 12B  is a schematic drawing showing an isometric view of the lift shown in  FIG. 12A  in its elevated position;  
         [0054]      FIG. 13A  is a schematic drawing showing an isometric view of a lift of the invention in its mobile position;  
         [0055]      FIG. 13B  is a schematic drawing in elevation showing the lift shown in  FIG. 13A  in its mobile position;  
         [0056]      FIG. 13C  is a schematic drawing in elevation showing the lift shown in  FIG. 13B  in its start position;  
         [0057]      FIG. 13D  is a schematic drawing showing a plan view of the base of the lift shown in  FIGS. 13A-13C ;  
         [0058]      FIG. 14  is a schematic drawing in elevation showing a lift of the invention;  
         [0059]      FIG. 15  is a schematic drawing showing an isometric view of a platform of the invention;  
         [0060]      FIG. 16  is a schematic drawing showing an isometric view of a platform of the invention; and  
         [0061]      FIG. 17  is a schematic drawing showing an isometric view of a platform of the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0062]     Preferred embodiments of the invention and its advantages are best understood by reference to  FIGS. 1-8  wherein like number refer to same and like parts. Table 1 lists reference numerals with their associated names and figures in which they appear.  
         [0063]     In some non-limiting embodiments of the invention, a multi-dimensional lift may comprise a means for moving a subject along an x-axis. In some non-limiting embodiments of the invention, a multi-dimensional lift may comprise a means for moving a subject along a y-axis. In some non-limiting embodiments of the invention, a multi-dimensional lift may include a means for moving a subject along a z-axis. The x-axis, y-axis, and z-axis may be perpendicular to each other. The lift may be positioned such that the x-axis and y-axis are parallel to the plane of the surface on which the lift rests.  
         [0064]     In the non-limiting embodiment shown in  FIG. 1 , the means for moving a subject along a z-axis may include scissor truss  12  and screw  13  operably engaged thereto, as shown in  FIGS. 1A and 1B . As screw  13  turns, the distance between joints  14  and  15  is reversibly reduced. This movement results in the elevation of platform  16  above base  11  from the start position shown in  FIG. 1A  to the raised position shown in  FIG. 1B .  
         [0065]     Platform  16  may include foot pads  18  and  19  as shown in  FIG. 1C . Foot pads of the invention may be ergonomically molded for added comfort. Platform  16  may also include low-rise perimeter rail  17 . This rail may serve a variety of functions including, without limitation, giving the worker a tactile indicator of proximity to the platform&#39;s edge and containing fluids, debris, or other materials associated with performance of the task at hand. The rail may also be configured to include touch-sensitive controls. Platform  16 , like other platforms suitable for use with lifts of the invention may be from about thirty inches to about fifty inches long by about nineteen inches to about thirty inches wide.  
         [0066]     Foot pad  18  and foot pad  19  may each be made of a resilient material for comfort. These pads may be any size or shape. Although not expressly show, lift  20  may be combined with other means of positioning a subject in a second or third dimension.  
         [0067]     According to the non-limiting embodiment shown in  FIG. 2 , the means for moving a subject along a z-axis may include truss  22 . Struts  28  and  29  of truss  22  may be movably connected to threaded rod  32  by threaded rings  24  and  25 . Threaded rod  32  is attached to base  21  by mount  30  and mount  31 . Mount  30  and mount  31  may be coupled with threaded rod  32  such that threaded rod  32  it is free to rotate but longitudinally fixed. Mount  30  and mount  31  may be fixed to base  21 . Motor  33  may be operably linked to threaded rod  32  to rotate threaded rod  32  about its longitudinal axis. Such rotation of threaded rod  32  closes the distance between threaded ring  24  and threaded ring  25  and reversibly raises platform  26  above base  21  from the start position shown in  FIG. 2A  to the elevated position shown in  FIG. 2B .  
         [0068]     Platform  26  may include low-rise perimeter ridge  27 . This ridge may serve a variety of functions including, without limitation, giving the worker a tactile indicator of proximity to the platform&#39;s edge and containing fluids, debris, or other materials associated with performance of the task at hand. Ridge  27  may also be configured to include touch-sensitive controls (not expressly shown). The surface of platform  26  may made of or covered with a resilient material for comfort.  
         [0069]     According to the non-limiting embodiment shown in  FIGS. 3A-3D , lift  40  according to the teachings of the invention may include means for moving a subject along both an x-axis and a z-axis. The means for moving a subject along an x-axis may include threaded rod  52  rotatably coupled with mount  50  and mount  51  and fixed to base  41 . The means for moving a subject along an x-axis may further include threaded ring  54  and threaded ring  55 . Threaded rings  54  and  55  may be movably coupled with threaded rod  52 . In addition, struts  48   a  and  48   b  may be fixed to each other at a preset angle at one end and rotatably attached at the opposite ends to threaded rings  54  and  55 . Struts  48   a  may be attached to opposite sides of threaded ring  54  for enhanced strength and/or stability. Although not expressly shown, struts  48   a  may be a single, solid piece that spans the width of threaded ring  54 . Rotation of threaded rod  52  by operably linked motor  53  may move threaded rings along the longitudinal axis of threaded rod  52 .  
         [0070]     The means for moving a subject along a z-axis may include scissor truss  42  and screw  43  operably engaged thereto, as shown in  FIGS. 3A, 3B  and  3 C. As screw  43  is turned by operably linked motor  56 , the distance between joints  44  and  45  is reversibly reduced. This movement results in the elevation of platform  46  above base  41  from the start position shown in  FIG. 3A  to the raised position shown in  FIG. 3C . Platform  46  may include perimeter bulge  47 . The surface of platform  46  may be radially graded such that together with bulge  47  it forms a shallow bowl.  
         [0071]     According to the non-limiting embodiment shown in  FIG. 4 , the means for moving a subject along a z-axis may include base  61 , platform  66 , and hydraulic pistons. Horizontal piston  62   a  and chamber  62   b  may be operably linked to vertical piston  63   a  and chamber  63   b . According this embodiment, motor  64  drives piston  62   a  into chamber  62   b  forcing hydraulic fluid through valve  65  into chamber  63   b . This in turn causes piston  63   a  and, therefore, platform  66  to rise above base  61  from the start position shown in  FIG. 4A  to the elevated position shown in  FIG. 4B . Platform  66  may be lowered by opening valve  65  to allow hydraulic fluid to flow back into chamber  62   b . Platform  66  may include perimeter rail  67  and foot pads  68  and  69  as shown in  FIG. 4C . Although not expressly shown, lift  60  may be configured to include voice-activated or foot actuated controls. Lift  60  may also be combined with other components to move the subject in along an x-axis and/or a y-axis.  
         [0072]     According to the non-limiting embodiment shown in  FIG. 5 , lift  70  according to the teachings of the invention may include a means for moving a subject along an x-axis, a y-axis, and a z-axis. The means for moving a subject along a z-axis may include base  71 , jack  73 , gear  74 , arm  75 , platform  76 , and support  77 . Support  77  may be fixed to arm  75  and platform  76  and arm  75  may be fixed to gear. Gear  74  is attached to the top of jack  73  such that it may rotate about an axis that is parallel to the longitudinal axis of jack  73 . Elevation of jack  73  in turn elevates platform  76  from the start position shown in  FIG. 5A  to the elevated position shown in  FIG. 5B . Lift  70  may also include a means for moving a subject in an x-z plane. The means for moving a subject in an x-z plane may include motor  81 , gear  80 , and gear  74 , wherein motor  81  rotates gear  80  and gear  80  is operably engaged with gear  74 . Rotation of gear  80  by motor  81  in turn rotates gear  74 . This causes platform  76  to rotate about the longitudinal axis of gear  74  in a plane that is parallel to both the x-axis and the y-axis ( FIG. 5C ). Platform  76  may also include foot pads  78  and  79  as shown in  FIG. 5C . Lift  70  may further include weight  72  to counter balance the weight of platform  76  with a subject resting thereon. The size and shape of base  71  may also be modified to counter balance platform  76  and stabilize lift  70 . Although not expressly shown, arm  75  may be a telescoping arm to improve the subject&#39;s access to a work space.  
         [0073]     According to the non-limiting embodiment shown in  FIG. 6 , the means for moving a subject along a z-axis may include a belt-driven elevation system. This system may include bearings  92 , threaded piston  93 , threaded cylinder  94 , and belt  95 . As shown in  FIG. 6A , bearings  92  are movably contained in recessed pockets in base  91 . Threaded piston  93  abuts bearings  92  and is operably connected to belt  95 . Threaded piston  93  is inserted into threaded cylinder  94 . Platform  96  is fixed to threaded cylinder  94  and may include perimeter angled rail  97 . Belt  95  is driven by motor  103 . Rotation of threaded piston  93  by belt  95  reversibly raises threaded cylinder  94  and therefore, platform  96  from its start position shown in  FIG. 6B  to its elevated position shown in  FIG. 6C . The degree of control over positioning along the z-axis may be selected by adjusting the number of threads per inch with high numbers allowing finer control. The speed of elevation may be selected by adjusting the speed of motor  103 , for example where motor  103  is a variable speed motor. Although not expressly shown, threaded piston  93  and cylinder  94  may include an anti-backdown control to prevent unwanted platform movement such as that which may occur in the case of belt slippage or failure. Although not expressly shown, lift  90  may also be configured to afford movement along an x-axis or a y-axis.  
         [0074]     A non-limiting, tiltable variation of the embodiment shown in  FIG. 6  is shown in  FIG. 7 . As shown in  FIG. 7A , lift  110  differs from lift  90  in that each threaded piston  113  has an underlying clutch  128  and motor  124  within base  111 . In addition, threaded piston  113  is rotatably coupled with belt  115  via clutch  118 . Platform  116  is flexibly coupled to threaded cylinder  114  by ball  128  and socket  129 . Although other configurations are possible, as shown in  FIG. 7A , ball  128  is fixed to platform  116  and socket  129  is fixed to threaded cylinder  114 . Threaded cylinder  114  is rotatably fixed to platform  116  by resilient annulus  126 . Platform  96  may include perimeter angled rail  97 .  
         [0075]     When clutch  118  is engaged, threaded piston  113  may be rotated by belt  115 . Clutch  127  may or may not be disengaged while threaded piston  113  is rotated by belt  115 . When clutch  118  is disengaged and clutch  127  is engaged, threaded piston  113  may be rotated by motor  124 , but not belt  115 . Thus, the z-axis position of each piston may be adjusted independently and/or coordinately. As a result, platform  116  may be tilted by partial elevation of one or more pistons.  FIG. 7C  shows the tilt resulting from modest elevation of the left-most piston and partial elevation of front and rear pistons. This tilt angle may be maintained while elevating the entire platform by disengaging clutches  127 , engaging clutches  118 , and rotating belt  115  as shown in  FIG. 7D . Motor  123 , clutches  118 , motors  124 , and clutches  127  may be electrically coupled to each other or to a controller (not expressly shown) to achieve synchronous or asynchronous control. Thus, controller may be configured to adjust the roll, pitch, and yaw of platform  116 . A controller may be configured to obviate the need for motor  123  and clutches  118  by coordinately operating motors  124  and clutches  127 .  
         [0076]     As with other embodiments of this invention, lift  110  may be configured to also include means of moving a subject along an x-axis and/or a y-axis. Lift  110  may also include any type of control mechanisms including means of hands-free control such as voice-activated controls and foot-activated controls. In applications where the subject may be on the lift for an extended period of time with the platform in a tilted position, it may be desirable to include one or more braces, boslters, or pads to support the subject&#39;s weight. Such supports may be fixed to platform  96  or base  91 .  
         [0077]     According to the non-limiting embodiment shown in  FIG. 8 , the means for moving a subject in an x-z plane may comprise piston  134 , platform  136 , threaded gear  140 , and gear rod  141 . As shown in  FIG. 8A , platform  136  may have motor  132  mounted thereon. Motor  132  may be operably connected to gear box  133  through which it may control the degree of the angle formed by the longitudinal axis of piston  134  and surface of platform  136  (“platform angle,”) ( FIG. 8B ). Piston  134  may also be operably linked to gear box  133 . Motor  144  may be operably linked to gear rod  141 , through which it may control the degree of the angle formed by the longitudinal axis of piston  134  and surface of base  131  (“base angle,”) ( FIG. 8B ). Piston  134  may be operably linked to gear rod  141  through threaded gear  140 . Although not expressly shown, motors  132  and  144  may be electronically or mechanically linked to maintain a desired sum of platform angle and base angle. For example, to keep platform  136  level, the sum of these angles would be maintained at 180°. To tip platform  136  toward the work space, the sum of these angles may be reduced below 180°. Alternatively, to tip platform  136  away from the work space, the sum of these angles may be increased above 180°.  
         [0078]     As shown in  FIG. 8B , expansion of piston  134  increases the range of possible movement in the x-z plane. This expansion may be achieved by operably linking piston  134  to motor  132 . In this case, motor  132  may drive a pump (not expressly shown) that reversibly fills piston  134  with hydraulic fluid.  
         [0079]     As shown in  FIG. 8C , lift  130  may be configured to include a means of moving a subject along a y-axis. The means of moving a subject along a y-axis may include threaded gear  140 , threaded rod  142  and motor  143 . It may also include piston  134  and platform  136 . Movement along a y-axis may be achieved where threaded rod  142  is rotated about its longitudinal axis such that threaded gear  140 , the female threads of which are operably engaged with the male threads of threaded rod  142 , moves in a positive or negative direction along the longitudinal axis of threaded rod  142 , which is the y-axis itself or parallel to the y-axis. This results in movement of the subject resting on platform  136  along a y-axis since platform  136 , gear box  133 , and piston  134  are all fixed to threaded gear  140 , at least with respect to the y-axis.  
         [0080]     As shown in  FIG. 8D , gear rod  140  and threaded rod  142  may preferably be parallel to each other. The ends of gear rod  140  and threaded rod  142  may each be rotatably mounted on supports  145  and  146  through hubs  147  and  148 . Supports  145  and  146  may be fixed to base  131 .  
         [0081]     Shin rests  135  may be fixed or adjustably mounted on platform  136  through arms  138  and rail  137 . Other types of ergonomic features may be elaborated on platform  136  or any other platform of the invention including, without limitation, foot pads, knee supports, hip rests, harnesses (e.g. leg harnesses or waist belts), and seats. Platform  136  may also be configured to include additional railings, proximity detectors, hands-free controls, or combinations thereof.  
         [0082]     According to the non-limiting embodiment shown in  FIG. 9 , the means for positioning a subject in three-dimensional space may include base  151 , a plurality of pistons  154 , and chair  156 . Each piston  154  may be operably coupled at each end to ball joints  152  and  153 . Each ball joint  152  may be fixed to base  151 . Each ball joint  153  may be fixed to chair  156  and may include a means to control the range of movement at the joint (a “movement governor,”). Each piston  154  may be connected to pump  155  by valve  158  and hose  159 . Valves  158  may be independently or coordinately opened or closed to insert, hold, or vent hydraulic fluid. In addition, control over movement of pistons  154  relative to ball joints  153  may be exercised independently or coordinately with control of piston expansion. Thus, partly filling the rear pistons while using the movement governor to reversibly lock all ball joints  153  has the effect of tilting chair  156  toward the work space as shown in  FIG. 9 . In addition, this action moves chair  156  and a subject resting thereon toward the work space. Although not expressly shown, partially filling the front pistons  154  and fully filling the rear pistons  154  would elevate chair  156 . By allowing some rotational movement of ball joints  153 , the chair seat could be held in an level, elevated position, biased toward the work space. Other positions relative to the work space may be obtained by adjusting the volume of hydraulic fluid in each piston  154  and the range of motion permitted at each ball joint  153 .  
         [0083]     Chair  156  may be fitted with any type of ergonomic apparatus to increase the comfort and safety of the subject resting thereupon including, without limitation, cushion  157 , arm rests, a waist belt, a shoulder harness, and instrument trays. Chair  156  may also be configured to include a support member that subjects straddle when seated. Although not expressly shown, this support member reduces the slippage and strain that a subject may experience while resting on chair  156  when it is tilted.  
         [0084]     A variation of the non-limiting embodiment shown in  FIG. 9  is shown in  FIG. 10 . Lift  160  differs from lift  150  in that platform  166  takes the place of chair  156  and supports a subject in an upright position as shown in  FIG. 10A . Platform  166  may be configured with rail  167 , which rises above platform  166  to about 75% of the height of the subject. Upon filling rear pistons  164 , the subject is moved toward the work space, here a bariatric patient, in a slightly recumbent position as shown in  FIG. 10B . This position allows some of the subjects weight to be borne by pads  168   a  and  168   b , thereby reducing the subject&#39;s fatigue.  
         [0085]     According to the non-limiting embodiment shown in  FIG. 11 , the means of moving a subject along a z-axis may comprise base  171 , pistons  172 , and layer  173 . Pistons  172 , like any pistons of the invention, may be gas pistons or hydraulic pistons. As shown in  FIG. 11A , the lower end of each piston  172  may be mounted on base  171 . The upper end of each piston  172  may be attached to z-layer  173 . Expansion of pistons  172  is coordinated such that layer  173  is elevated as shown in  FIG. 11B .  
         [0086]     Also as shown in  FIG. 11A , the means for moving a subject along an x-axis may include x-layer  176  and rail  175  operatively engaged in track  174 . Although not expressly shown, rail  175  may be moved along track  174  by a motor either mounted on or in layer  173 , layer  176  or base  171 . For example, if a motor is included in the body of layer  173 , it may be attached to a tire, wheel, or gear that engages rail  175  and moves it relative to track  174 . Alternatively, if a motor is mounted on base  171 , it may move rail  175  relative to track  174  through a systems of cables and pulleys (not expressly shown). In either case, movement along an x-axis is realized as shown in  FIG. 11C .  
         [0087]     Also as shown in  FIG. 11A , the means for moving a subject along a y-axis may include platform  179  (or y-layer  179 ) and rail  178  operatively engaged in track  177 . Although not expressly shown, rail  178  may be moved along track  177  by a motor either mounted on or in layer  176 , platform  179  or base  171 . For example, if a motor is included in the body of layer  176 , it may be attached to a tire, wheel, or gear that engages rail  178  and moves it relative to track  177 . Alternatively, if a motor is mounted on base  171 , it may move rail  178  relative to track  177  through a systems of cables and pulleys (not expressly shown). In either case, movement along a y-axis is realized as shown in  FIG. 11D . Movement of rails in tracks may be facilitated by application of lubricants. In addition, rail/track movement may be facilitated by use of bearings or other such means.  
         [0088]     As shown in  FIG. 11E , layer  173  and layer  176  may each have a center hole, which may be used, for example, to accommodate extending cables or other connections from these layers to a base-mounted motor. In addition, platform  179  may include grate  180 . If lift  170  is used for surgical procedures which may result in the production of substantial waste fluids, platform  179  may be configured to include a drain (e.g. underlying grate  180 ; not expressly shown).  
         [0089]     According to the non-limiting embodiment shown in  FIG. 12 , the means for moving a subject along a z-axis may include base  191 , platform  196 , a plurality of springs  197 , and bladder  198 . As shown in  FIG. 12A , springs  197  are in their resting state and bladder  198  is deflated. Platform  196  may be raised from its start position shown in  FIG. 12A  to its elevated position shown in  FIG. 12B  by inflating bladder  198 . In the elevated position, springs  197  are stretched such that as bladder  198  is deflated, springs  197  pull platform  196  back toward its start position. Although not expressly shown, bladder  198  may be donut-shaped with a pump positioned in the center void. The pump may be operably connected to bladder  198  and used to inflate or deflate bladder  198 . Although not expressly shown, rods may be positioned along the center axis of each spring  197  such that they would not interfere with expansion or contraction of springs  197 , but would block spring compression. This would prevent platform  196  from going so low as to damage bladder  198  and any other components between base  191  and platform  196 .  
         [0090]     Also as shown in  FIG. 12A , the means for moving a subject in an x-y plane may include base  191 , casters  192 , retractable blocks  193 , and drive tire  195  operably linked to a motor (not expressly shown). The orientation of drive tire  195  may be adjusted to direct movement of lift  190 . A tiltable variation of the embodiment shown may be created by eliminating springs  197  and using four smaller bladders  198 , one at each corner of platform  196 . Synchronous and asynchronous movement at each corner may be achieved by operably linking these bladders to a suitable controller.  
         [0091]     Another variation of the non-limiting embodiment shown in  FIG. 12  is shown in  FIG. 13 . Lift  200  differs from lift  190  in that drive ball  205  takes the place of drive tire  195  ( FIG. 13A ).  
         [0092]     As shown in  FIG. 13B , casters  202  in their extended position raise drive ball  205  off the surface of the floor to facilitate transport and storage of lift  200 . Once lift  200  is delivered to the location of intended use, such as an operating room, drive ball  205  may be contacted with the floor by retracting retractable blocks  203  on which casters  202  are fixed ( FIG. 13C ).  
         [0093]     The direction of movement in the x-y plane depends on the direction of rotation of drive ball  205 . This direction is determined by combined action of drive drums  210  and  214 , which each contact drive ball  205 . Thus, lift  200  may also include a controller that coordinates the revolutions per minute and direction of rotation of each drive drum. Motor  208  is operatively linked to drive drum  210 . Likewise, motor  212  is operatively linked to drive drum  214 . This linkage may be direct, as shown, or indirect. Where the linkage is indirect, one or more gears and belts may be used to rotate the drive drum(s). While not expressly shown, the present invention also contemplates other embodiments in which a single motor and a system of gears may determine the direction of rotation of drive ball  205 . Motors  208  and  212  may be operatively linked to separate power sources  209  and  213 , respectively, as shown in  FIG. 13D . Alternatively, motors  208  and  212  may be operatively connected to a single power source (not expressly shown).  
         [0094]     As shown in  FIG. 13D , drive drums  210  and  214  lie within a plane, are oriented at a 90° angle relative to each other, and each contact drive ball  205 . One or more tensioners may be used and each one may or may not be spring-loaded to help maintain contact between drive ball  205  and drive drums  210  and  214 . In a relatively simple embodiment, tensioner  215  includes a drum or rod rotatably coupled to a support and is oriented such that the longitudinal axis of the rod or drum forms a right triangle with the longitudinal axes of drive drums  210  and  214 . Tensioner  215  may or may not be in the same plane as drive drums  210  and  214 . Drive drums  210  and  214  may be cylinder-shaped as shown in  FIG. 13D . Alternatively, drive drums of the invention may have any suitable shape such as, for example, a wheel or tire shape. Drive drums of the invention may include a resilient covering with a high co-efficient of friction to enhance the transfer of movement to the drive ball.  
         [0095]     According to the non-limiting embodiment shown in  FIG. 14 , a lift of the invention may include vertical base  221 , joint  222 , hydraulic arm  222 , joint  224 , and platform  226 . Lift  220  may also include, although not expressly shown, necessary pumps, motors, gears, and controls. According to this embodiment, a subject may be recumbently positioned relative to a work space.  FIG. 14  shows one example where a surgeon is positioned above a particularly large bariatric patient. Platform  226  may be configured to include a head rest, foot-controls, voice-activated controls, instrument tray, conventional power plugs, lights, and proximity detectors (e.g. to avoid inadvertently bumping the patient).  
         [0096]     Indeed, any lift of the invention may include any of the items listed in this description or combinations thereof. For example, lifts of the invention may include, without limitation, foot pads, low-rise rails, ridges, or bulges, safety railings, harnesses, arm rests, chairs, stools, foot-controls, voice-activated controls, instrument trays, standard or appliance power outlets (e.g. 110-120 volt, 15 amp, twin phase 60 Hz North American outlets or 220-240 volt,  30  amp, single phase  50  Hz European outlets), lights, gas pumps, vacuum pumps, suction hoses, fluid reservoirs, proximity detectors and combinations thereof. In addition, any portion of a lift of the invention may be covered with a non-woven material. These materials may be used, for example, to protect portions of the lift that may otherwise come into contact with patient fluids, tissues, or other biohazards. To prepare the lift for subsequent use (e.g. with another patient), the non-woven materials may be simply discarded as appropriate. Such use of non-woven materials may reduce the spread of infectious agents or other biohazards and may reduce the amount of cleaning and sanitizing required between surgeries .  
         [0097]     According to the non-limiting embodiment shown in  FIG. 15 , platform  230  may include circular, touch-sensitive, foot control  231  that is raised above the upper surface of platform  230 . Foot control  231  may have directional arrows molded into its surface for the operator&#39;s convenience. While not expressly shown, foot control  231  may be operably coupled with one or more means for moving a subject along an x-axis and a y-axis. Platform  230  may also include touch-sensitive up button  232  and touch-sensitive down button  233 . These buttons may be operably liked to the means for moving a subject along a z-axis. They may be configured to raise or lower platform  230  at a fixed rate or at a rate determined by the pressure applied. Buttons  232  and  233  may be actuated by the subject&#39;s foot. Although not expressly shown, foot control  231  and buttons  232  and  233  may be recessed below the surface of platform  230  to minimize inadvertent contact.  
         [0098]     According to the non-limiting embodiment shown in  FIG. 16 , platform  235  may include contact-sensitive ridges. Forward ridge  236  and reverse ridge  239  may be operably connected to a means for moving a subject along a y-axis. Left ridge  237  and right ridge  238  may be operably connected to a means for moving a subject along an x-axis. Platform  235  may also include touch-sensitive up button  240  and touch-sensitive down button  241 . These buttons may be operably liked to the means for moving a subject along a z-axis. They may be configured to raise or lower platform  235  at a fixed rate or at a rate determined by the pressure applied. Ridges  236 ,  237 ,  238 , and  239  and buttons  240  and  241  may be actuated by the subject&#39;s foot.  
         [0099]     According to the non-limiting embodiment shown in  FIG. 17 , the means for controlling platform movement includes pressure-sensitive knee pads  249   a  and  249   b respectively mounted on arms  250   a  and  250   b . Knee pads  249   a  and  249   b  may be configured in any ergonomic form to contact the subject&#39;s knees. For example, while not expressly shown, knee pads of the invention may partially or completely surround the subject&#39;s knees. Knee pads  249   a  and  249   b  may each be operably linked to a means for moving a subject along an x-axis according the invention. Thus, lateral pressure applied by the subject to either knee pad will result in positive or negative movement along the x-axis. Knee pads  249   a  and  249   b  may each be operably linked to a means for moving a subject along a y-axis according the invention. Thus, forward or reverse pressure applied by the subject to either knee pad will result in positive or negative movement along the y-axis. Alternatively, forward pressure to knee pad  249   a  may result in forward movement, while forward pressure on knee pad  249   b  may result in reverse movement.  
         [0100]     Enclosed foot pedals  251   a  and  251   b  may be fixed on arms  250   a  and  250   b  as shown in  FIG. 17 . These pedals may be operably coupled to a means for moving a subject along a z-axis such that application of upward pressure by the subject will raise platform  245  and application of downward pressure will lower platform  245 .  
         [0101]     While not expressly shown, platforms of the invention may have any configuration. In some embodiments, for example, platforms are substantially planar. In other embodiments, the platform may be configured to include curves or steps. During a surgical procedure it may be necessary to move along the length (height) of a recumbant patient (e.g. moving from the head to the chest to the pelvis to the feet). On a planar platform in a level position, the bariatric surgeon may have to readjust the platform height each time. One option afforded the surgeon by lifts of the invention would be to simply tilt the platform such that it is higher near the patient&#39;s feet than at the patient&#39;s chest. Another option provided by the invention is a platform that includes a slope or stair-step configuration. In applications where the subject may experience discomfort from standing on a sloped surface, a stair-step or other contour may be preferred.  
         [0102]     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the invention as defined by the following claims.  
                               TABLE 1                                   No.   Feature Name   FIGS.                            10   lift   1A, 1B            11   base   1A, 1B            12   scissor truss   1A, 1B            13   screw   1A, 1B            14   joint   1A, 1B            15   joint   1A, 1B            16   platform   1A, 1B, 1C            17   perimeter angled rail   1A, 1B, 1C            18   foot pad   1C            19   foot pad   1C            20   lift   2A, 2B            21   base   2A, 2B            22   truss   2A, 2B            23   screw            24   threaded ring   2A, 2B            25   threaded ring   2A, 2B            26   platform   2A, 2B, 2C            27   perimeter ridge   2A, 2B, 2C            28   strut   2A, 2B            29   strut   2A, 2B            30   mount   2A, 2B            31   mount   2A, 2B            32   threaded rod   2A, 2B            33   motor   2A, 2B            40   lift   3A, 3B, 3C            41   base   3A, 3B, 3C            42   truss   3A, 3B, 3C            43   screw   3A, 3B, 3C            44   threaded ring   3A, 3B, 3C            45   threaded ring   3A, 3B, 3C            46   platform   3A, 3B, 3C, 3D            47   perimeter bulge   3A, 3B, 3C, 3D            48a   strut   3A, 3B, 3C            48b   strut   3A, 3B, 3C            49a   strut   3A, 3B, 3C            49b   strut   3A, 3B, 3C            50   mount   3A, 3B, 3C            51   mount   3A, 3B, 3C            52   threaded rod   3A, 3B, 3C            53   motor   3A, 3B, 3C            54   threaded ring   3B            55   threaded ring   3A, 3B, 3C            56   motor   3A, 3B, 3C            60   lift   4A, 4B            61   base   4A, 4B            62a   piston   4A, 4B            62b   chamber   4A, 4B            63a   piston   4A, 4B            63b   chamber   4A, 4B            64   motor   4A, 4B            65   valve   4A, 4B            66   platform   4A, 4B, 4C            67   perimeter rail   4A, 4B, 4C            68   foot pad   4C            69   foot pad   4C            70   lift   5A. 5B            71   base   5A, 5B, 5C            72   weight   5A, 5B            73   jack   5A, 5B            74   gear   5A, 5B            75   arm   5A, 5B, 5C            76   platform   5A, 5B, 5C            77   support   5A, 5B            78   foot pad   5C            79   foot pad   5C            80   elongated gear   5A, 5B            83   motor   5A, 5B            90   lift   6B, 6C            91   base   6A, 6B, 6C            92   bearing   6A            93   threaded piston   6A            94   threaded cylinder   6A            95   belt   6A, 6B, 6C            96   platform   6A, 6B, 6C            97   rail   6A, 6B, 6C           103   motor   6B, 6C           110   lift   7B, 7C, 7D, 7E           111   base   7A, 7B, 7C, 7D, 7E           113   threaded piston   7A, 7B, 7C, 7D, 7E           114   threaded sleeve   7A, 7B, 7C, 7D, 7E           115   belt   7A, 7B, 7C, 7D, 7E           116   platform   7A, 7B, 7C, 7D, 7E           117   rail   7B, 7C, 7D, 7E           118   clutch   7A, 7B, 7C, 7D, 7E           123   motor   7B, 7C, 7D, 7E           124   motor   7A           126   resilient annulus   7A           127   clutch   7A           128   ball   7A           129   socket   7A           130   lift   8A, 8B, 8C, 8D           131   base   8A, 8B, 8C, 8D           132   motor   8A, 8B           133   gear box   8A, 8B           134   piston   8A, 8B, 8C, 8D           136   platform   8A, 8B, 8C, 8D           137   rail   8A, 8B, 8C, 8D           138   arm   8A, 8B, 8C, 8D           139   shin rest   8A, 8B, 8C, 8D           140   threaded gear   8A, 8B, 8C, 8D           141   elongated gear rod   8A, 8B, 8C, 8D           142   threaded rod   8A, 8B, 8C, 8D           143   y-motor   8A, 8B, 8C, 8D           144   motor   8A, 8B, 8C, 8D           145   support   8A, 8B, 8C, 8D           146   support   8C, 8D           147   hub   8D           148   hub   8D           150   lift   9           151   base   9           152   ball joint   9           153   ball joint   9           154   piston   9           155   pump   9           156   chair   9           157   cushion   9           158   valve           159   hose           160   lift   10A, 10B           161   base   10A, 10B           162   ball joint   10A, 10B           163   ball joint   10A, 10B           164   piston   10A, 10B           165   pump   10A, 10B           166   platform   10A, 10B           167   rail   10A, 10B           168a   shin pad   10A, 10B           168b   torso pad   10A, 10B           169   hose   10A, 10B           170   lift   11A, 11B, 11C           171   base   11A, 11B, 11C           172   piston   11A, 11B, 11C           173   z-layer   11A, 11B, 11C           174   track   11A, 11B, 11C           175   rail   11A, 11B, 11C           176   x-layer   11A, 11B, 11C           177   track   11A, 11B, 11C           178   rail   11A, 11B, 11C           179   platform   11A, 11B, 11C           180   grate   11A, 11B, 11C           190   lift   12A, 12B           191   base   12A, 12B           192   castor   12A, 12B           193   retractable block   12A, 12B           194   castor well   12A, 12B           195   tire   12A, 12B           196   platform   12A, 12B           197   spring   12A, 12B           198   bladder   12A, 12B           200   lift   13A, 13B, 13C           201   base   13A, 13B, 13C, 13D           202   castor   13A, 13B, 13C, 13D           203   retractable block   13A, 13B, 13C, 13D           204   castor well   13A, 13B, 13C, 13D           205   drive ball   13A, 13B, 13C, 13D           206   platform   13A, 13B, 13C, 13D           207   piston   13A, 13B, 13C           208   motor   13B, 13C, 13D           209   power source   13B, 13C, 13D           210   drive drum   13B, 13C, 13D           211   support   13B, 13D           212   motor   13B, 13C, 13D           213   power source   13B, 13C, 13D           214   drive drum   13B, 13C, 13D           215   tensioner   13D           220   lift   14           221   base   14           222   hydraulic arm   14           225   ball joint   14           226   platform   14           230   platform   15           231   direction switch   15           232   down button   15           233   up button   15           235   platform   16           236   forward ridge   16           237   left ridge   16           238   right ridge   16           239   rear ridge   16           240   down button   16           241   up button   16           245   platform   17           246   rail   17           247   pad   17           248   proximity detectors   17           249   knee pad   17           250   arm   17           251   foot pedal   17