Abstract:
A buoyancy compensation device and method for a scuba diver or other underwater object, which decreases buoyancy by actively pumping air from a flexible bladder while the diver or object is in any orientation, said bladder having internally a manifold assembly providing access to pockets of air anywhere within the bladder. In addition, said device and method may be adapted for automatically diving, surfacing, or maintaining a predetermined water depth while the diver or object is in any orientation and while the diver&#39;s or object&#39;s orientation changes, including a sensor for measuring water depth, one or more control inputs for selecting a depth, and a controller unit that determines descent rate, ascent rate, or maintenance of a selected depth based on monitoring the water depth, the setting of the control inputs, and the diver&#39;s or objects previous habits and behavior.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to provisional application 61/458,137 filed on Nov. 18, 2010. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX 
       [0003]    Not applicable. 
       FIELD OF THE INVENTION 
       [0004]    The invention pertains to scuba diving equipment. Specifically, the invention pertains to automatic buoyancy compensation for a scuba diver or underwater device. 
       BACKGROUND OF THE INVENTION 
       [0005]    Scuba divers, deep sea divers, and other submarine applications most easily maintain a fixed depth by anchoring themselves to a submerged fixture or connecting to a tether from the surface. Lacking such an anchor or tether requires continuously adjusting the buoyancy of the diver or object to maintain a specific depth. In particular, scuba divers are required to learn to carefully “balance” atop a parabolic buoyancy equilibrium curve while submerged. Failure to do so risks plummeting deeper at an increasing rate or rising at an ever increasing rate, either of which may result in injury or death. 
         [0006]    By way of explanation, a diver typically attaches lead weights to himself in order to achieve negative buoyancy and wears an inflatable life jacket, also known as a buoyancy compensation device or BCD, containing a bladder which can be inflated with a variable amount of air or diving gases, in order to create positive buoyancy. A diver attempts to inflate the BCD with exactly the right amount of air (gases) so as to create neutral buoyancy. It is understood that, within this document, the words “air” and “gas” may be used interchangeably. This positive buoyancy compensates exactly for any negative buoyancy caused by weights, tanks, dive suit, and the diver&#39;s own body. The BCD, with its variable positive buoyancy, is necessary because the buoyancy of the diver combined with that of his equipment will change during the course of a dive. For example, as the dive progresses, the diver&#39;s compressed air tank becomes depleted, resulting in a lightening of said tank and an increase in buoyancy. As another example, the diver may be wearing a temperature-insulating wetsuit comprising a compressible fabric. The buoyancy of this fabric decreases with increased depth and the accompanying increase in water pressure. 
         [0007]    Once neutral buoyancy is achieved, should the diver venture deeper, his sources of compressible positive buoyancy, such as his lungs, wet suit, dry suit gases, sinuses, inflatable bladder within a buoyancy compensation device, etc., will reduce in volume due to the increased water pressure. This reduced volume reduces the effect of the positive buoyancy which tends to make the diver sink, which decreases the volume of the compressible positive buoyancy further, resulting in the tendency to sink at an ever increasing rate. 
         [0008]    On the other hand, should a diver, having achieved neutral buoyancy, venture to a shallower depth, his sources of compressible buoyancy expand in volume due to decreased water pressure. In turn, the expanded volume provides increased positive buoyancy resulting in the tendency for the diver to rise, which again increases his buoyancy and pushes the diver toward the surface with ever increasing force. 
         [0009]    A diver who begins to sink and fails to check his decent risks any numbers of hazards, such as ear damage, nitrogen narcosis, decompression sickness (“the bends”), asphyxiation and ultimately death. A diver that ascends unchecked risks air embolism, damaged lungs and sinuses, decompression sickness and, again, death. 
         [0010]    Since the use of BCDs began, divers have been required to add air or exhaust air from their BCDs in order to compensate for any ascent or descent. Over a limited depth range, skilled divers can maintain buoyancy equilibrium by adjusting the average amount of air in their lungs. Both this skill and the proper adjustment of BCDs require considerable training and practice. Adding to the difficulty in perfecting such skill is the fact that the diver must compensate for the buoyancy of his body and equipment while in any orientation during the dive. This combined buoyancy includes the intrinsic buoyancy of the human body as well as periodic, sudden, or gradual changes to the buoyancy of the human body and equipment. As examples, intrinsic buoyancy may be due to the body mass index of the diver. Periodic changes in buoyancy might be caused by the diver&#39;s inhalation and exhalation of air. A sudden decrease in buoyancy might be caused by grasping an object less buoyant, such as a piece of mineral or metal. A sudden increase in buoyancy might be caused by grasping or otherwise attaching to something more buoyant, such as an inflated object. Gradual increased buoyancy might occur due to consuming compressed air used for breathing. Depth-related changes in buoyancy might be due to, for example, the compressibility of the diver&#39;s lungs, sinuses, and wet suit or dry suit. The diver&#39;s orientation may change in the process of swimming, for example, horizontally face down, vertically head up, vertically head down, or horizontally face up. 
         [0011]    While adding air to a bladder typically requires actuation of a single valve, removing air requires that the diver be cognizant of his orientation with respect to gravity so as to either actuate one of multiple of air release valves incorporated into his BCD, or to reorient himself, so that the air release valve chosen is in contact with, and thus able to vent, any remaining air within the bladder. 
         [0012]    Buoyancy compensation for underwater vehicles or for devices not under human control is particularly difficult. Although the same tendency to sink or rise occurs with such a device, there is no human present to adjust the amount of buoyancy. 
         [0013]    U.S. Pat. No. 5,482,405 describes an apparatus for counterbalancing divers. The term “counterbalancing” is synonymous with the more common term “buoyancy compensation.” The patent includes descriptions of one or more valves, a depth sensor, an inflatable life jacket, also known as an air bladder, one or more control inputs that can be adjusted by the diver, and a battery-powered electronic control unit that, by monitoring the depth and the diver&#39;s controls and by performing various calculations, is capable of actuating one or more valves to add or remove air from the life jacket. Said monitoring and calculations are intended to aid the diver in maintaining a chosen depth, ascending, or descending to a target depth. 
         [0014]    Of particular note, while U.S. Pat. No. 5,482,405 describes an electronically controlled valve for allowing air to escape from the life jacket, it fails to mention that, in order for the apparatus to work reliably, said valve must be able to vent air from the vest while the vest and diver are in any orientation. For example, if said valve is below (at a greater depth than) a pocket of air trapped in the life jacket, the valve will be useless in venting air out of the life jacket. This is because the secluded air will tend toward the surface while the valve, situated at a greater depth, is incapable of providing a means for the air to escape the life jacket. Thus the invention as disclosed by that patent is unworkable. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    The present invention is directed toward buoyancy compensation for a diver or mobile underwater device. The buoyancy compensation apparatus comprises novel devices and concepts capable of being easily adapted to equipment already in use by scuba divers. In the invention, an inflatable vest, or bladder, typically worn by divers is fitted with an internal manifold for accessing and removing air from any part of the bladder regardless of the orientation of the bladder and diver, or the amount of air remaining in the bladder. The bladder in its typical form, unmodified by the present invention, includes a valve and a hose by which air can be added to the bladder for the purpose of increasing buoyancy. With the addition of the manifold previously described, the same hose previously mentioned may be used to remove air from the bladder. The hose is connected to an evacuation means to remove air from the bladder by way of the manifold for the purpose of decreasing buoyancy. The evacuation means may be a pump or a venturi. In the case of a pump, it may be manually operated by a diver, or may be motor driven, This motor may be powered by electricity, compressed air, or other known means. 
         [0016]    A motor-driven evacuation pump or a valve-controlled venturi may further be actuated by an electronic controller. This controller also controls a valve for adding air to the bladder. Thus, the controller is capable of establishing a desired amount of air in the bladder, and of subsequently increasing or decreasing that amount. The controller is connected to a pressure transducer for the purpose of determining the current water depth. The controller also receives control settings from an arrangement of switches, knobs, joysticks, or other control inputs. The combination of control inputs and depth information allows a predetermined depth to be achieved and maintained by the controller, independent of human interaction. Some of the components described, such as valves, hoses, manifold, and pressure transducer may replace similar components in standard diving equipment, that is, diving equipment unmodified by the present invention. Conversely, the components typical of standard diving equipment may be kept intact for redundancy and thus augmented by the additional capabilities of the present invention. 
         [0017]    The controller is capable of determining both instantaneous water depth and of recording water depth over a period of time. Likewise, the controller can record the history of control settings operated by a human diver and correlate these with the diver&#39;s depth over time. With this information, the controller can change its control algorithm in response to the behavior of a particular diver or situation. In other words, the behavior can adapt over time. Such adaptive behavior may conserve air, reduce the diver&#39;s effort level, and increase safety. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0018]    To better understand the present invention, reference may be had to the following description of exemplary embodiments thereof, considered in conjunction with the accompanying drawings, in which: 
           [0019]      FIG. 1  shows a block diagram of an exemplary embodiment of an automatic buoyancy compensation system that can be worn and controlled by a human diver. 
           [0020]      FIG. 2  shows a view of a bladder containing air or other gases for providing positive buoyancy. A cut away portion of the diagram shows an exemplary manifold used for adding or removing air from the bladder. 
           [0021]      FIG. 3  shows three different exemplary manifolds used for adding and, especially, for removing air from the aforementioned bladder. These manifolds vary in geometry, but serve the same function. In particular, the manifold geometry allows access to and removal of secluded pockets of air in the aforementioned bladder. 
           [0022]      FIG. 4  shows details of the input valve assembly, revealing the routing of air to and from a pneumatic bladder. 
           [0023]      FIG. 5  shows an exemplary combined user control and user display apparatus for use by a human diver to interact with the buoyancy compensation system. 
           [0024]      FIG. 6  shows an exemplary embodiment of the buoyancy compensation system fitted to a human diver. 
           [0025]      FIG. 7  shows a block diagram of an exemplary embodiment of a manual buoyancy compensation system that can be worn and controlled by a human diver. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    The present invention discloses a novel method for automatic buoyancy compensation of any underwater object, including a human diver. The preferred embodiment allows the diver to control the automatic buoyancy compensator via control inputs. In addition, any of a number of means to communicate status back to the diver (visual, auditory, tactile) may be employed to inform the diver of current conditions and thus facilitate the diver&#39;s control of the apparatus. 
         [0027]      FIG. 1  shows a schematic representation of a preferred embodiment of the entire buoyancy compensation system intended to be worn and used by a human diver. Display/input module  1  allows the diver to provide control inputs to control module  3  and to observe status information produced by control module  3 . The flow of control settings and status information are indicated, respectively, by the arrows from display/input module  1  to control module  3  and from control module  3  to display/input module  1 . Control module  3  may be microcomputer-based or based upon other known means. 
         [0028]    Power supply  2  provides electrical power to the entire system and contains a battery or similar power source. Depth sensor  4  conveys instantaneous depth information to control unit  3 , which, in response to control inputs from display/input module  1 , actuates input valve  12  to add air to inflatable bladder  8  from pressurized air connection  11  due to actuating control signal  12 A, or to remove air from inflatable bladder  8  using evacuation means  6  via connection  6 B out of exhaust vent  7  due to actuating control signal  6 A. Although separate accesses from valve assembly  12  and evacuation pump  6  to bladder  8  are feasible, the preferred embodiment utilizes a common access  5 . Bladder  8  thus inflates or deflates due to the actions of controller  3 , thereby providing increased or decreased buoyancy; respectively. Any change of depth resulting from this buoyancy change is communicated to the diver via display/input module  1 . 
         [0029]    The apparatus of  FIG. 1  is adapted to be used with known components of scuba gear, notably bladder  8  and inflator hose assembly  9 . Inflator hose assembly  9  operates by known means and provides the diver with a means of adding or removing air from bladder  8  using push button valves  9 A or  9 B, respectively, or adding air by blowing into mouthpiece  9 C. The present invention maintains this capability thus providing an alternate or backup system by which the diver can adjust his buoyancy. In  FIG. 1 , air connection  10  provides a downstream source of pressurized air, passed from pressurized air connection  11  via input valve assembly  12 , to inflator hose assembly  9 . Pushbutton  9 A admits pressurized air into assembly  9  which is coupled, via coupling  12 D within input valve assembly  12 , to common access  5 , thus providing an alternate means for inflating bladder  8 . Because assembly  9  is thus coupled to common access  5 , it is also possible for the diver to release air from bladder  8  by depressing push button release valve  9 B thus exhausting it through mouthpiece  9 C, all via known means. Alternatively, connection  10  may be an electrical or mechanical means of signaling input valve assembly  12 , in which case pressurized air will be passed, via valve  12 C within input valve assembly  12 , directly from pressurized air connection  11  to common access  5 . Valve  12 C is illustrated in  FIG. 4 . 
         [0030]      FIG. 2  shows details and internal components of inflatable bladder  8 , the depicted shape of which is exemplary. Typically, bladder  8 , of which the interior surface  8 ′ is revealed in cross section, is comprised of flexible material which increases in encompassed volume when inflated by pressurized air, resulting in increased buoyancy for the diver, and deflates as said air is released resulting in decreased buoyancy for the diver. Inflatable bladder  8  is typically covered with protective fabric  24 . Common access  5  is the means by which air is added or removed from bladder  8 . Bladder  8 , fabric  24 , and common access  5  are known components of scuba equipment. However, the present invention contributes manifold  13  which in  FIG. 2  takes the form of a semi-rigid perforated tube; that is, while the tube may be bent as shown in  FIG. 2 , the cross-section of the tube is resistant to collapse. Junction  14  connects common access  5  with manifold  13 . Manifold  13  is fitted so as to contact secluded pockets of air which may form anywhere within bladder  8  as it shrinks when air is removed. The tube&#39;s perforations allow air to be removed from the bladder no matter where located within the bladder, and no matter what the bladder&#39;s orientation. By using evacuation means  6 , the secluded air can be removed regardless of it being at greater, equal, or lesser pressure than the water pressure at exhaust vent  7 . 
         [0031]      FIG. 3  shows three exemplary embodiments of manifold  13  each of which may be suited to contact, and thus evacuate, using evacuation means  6 , secluded pockets of air within bladder  8 . Manifold embodiment  13 A shows a close up portion of the manifold as represented in  FIG. 2  clearly showing holes  15  perforating the walls of the manifold. Manifold version  13 B shows the holes of  13 A replaced by hollow branches  16 , which are open at ends  16 A. Manifold embodiment  13 C shows branches  16  meeting at a common junction  14 . Again, the branches  16  are open at ends  16 A. All three embodiments of manifold  13  provide means to access pockets of air secluded within bladder  8 . 
         [0032]      FIG. 4  shows schematic detail of input valve assembly  12 , shown encompassed by a dashed line. Pressurized air connection  11  passes pressurized air to junction  12 B which couples to air connection  10  leading to inflator hose assembly  9 . Junction  12 B also passes pressurized air to valve  12 C, which is controlled by controller  3  by means of actuating signal  12 A. In response, valve  12 C passes pressurized air to coupling  12 D, which both passes pressurized air to connection  12 H feeding inflator hose assembly  9  and coupling  5 A which feeds common access  5 , by which bladder  8  is inflated. The pressurized air within bladder  8  may be removed through common access  5  and coupling  5 A to connection  6 B leading to evacuation means  6 . 
         [0033]      FIG. 5  shows an exemplary combined display and control module  1  for use by a human diver. Cuff  19  attaches the control and display unit to the wearer&#39;s forearm. Display/Control module  1  comprises display screen  17 , which may display simple numeric symbols as shown or may provide any video display of known means, control buttons  18  as shown, or a variety of alternate control elements of known means, including recognition of voice or other sound-based commands from the diver, illuminated indicators  12 , and additional audible and tactile indicators.  FIG. 4  serves to illustrate that some means of providing control by, and status to, the human diver is required. Display/Control module  1  also contains the intelligent controller, based on a microprocessor or other known means, by which the valves and air evacuation means are actuated, and diver&#39;s status and control are provided. 
         [0034]      FIG. 6  shows an exemplary embodiment of the buoyancy compensation system fitted to a human diver  21  wherein bladder  8  surrounded by protective fabric  24  is behind the diver. Bladder  8  surrounded by fabric  24  may alternatively be partly or entirely in front of the diver as is known in common art.  FIG. 6  shows the user control and display apparatus  1 , as an example, attached to the diver&#39;s left arm as might be preferred by a right handed diver. Electrical connections  22  connect control signals to and status signals from integrated assembly  23 . Integrated assembly  23 , as an exemplary embodiment, comprises input valve assembly  12 , evacuation pump  6 , controller  3 , depth sensor  4 , power supply  2 , and their associated interconnections. Alternatively, power supply  2  and depth sensor  4  can be located within control and display apparatus  1 . It should be noted than any and all other components of integrated assembly  23  could be implemented separately or located within control and display apparatus  1 , as examples. 
         [0035]      FIG. 6  also shows the preferred locations, relative to the human diver, of common access  5  to bladder  8 , exhaust vent  7 , inflator hose assembly  9 , pressurized air connection  11  coming from the diver&#39;s low pressure air supply, and air connection  10 . The preferred embodiment shown in  FIG. 6  shows how the present invention may be adapted to known, commercially available scuba equipment. In particular, the current invention is easily adapted to both the bladder and inflator hose assembly of several commercially available buoyancy compensating vests. 
         [0036]      FIG. 7  shows a view similar to  FIG. 1 , but lacking, display and control module  1 , power supply  2 , controller  3 , and depth sensor  4 . The view of  FIG. 7  shows a manually operated version of the present invention. In this view, bladder  8 , with internal manifold  13 , inflator hose assembly  9 , input valve assembly  12 , pressurized air connection  11 , common access  5 , and associated elements remain unchanged. However, in  FIG. 7 , evacuation means  6  is a manual pump operated by the human diver. This rudimentary form of the invention relies on the human diver to maintain the desired buoyancy, but still allows said buoyancy to be adjusted solely by inflator assembly inflation valve  9 A, for an increase in buoyancy, or by manually operating evacuation means  6 , in this case a pump, for a decrease in buoyancy. Evacuation of the bladder can be accomplished while in any orientation. One exemplary embodiment of the manually operated evacuation pump  6  would be a flexible, semi-rigid hollow canister with, at either end, one-way air valves, venting air out of the bladder, the canister being a size and shape easily grasped by a human hand such that squeezing the canister forces air out of exhaust vent  7  and releasing the canister allows it to return to its previous shape, which draws air from bladder  8  via connection  6 B. It is understood that the components of  FIG. 7  may be fitted to a human diver in a similar fashion to the way the components of  FIG. 1  are shown fitted to the diver in  FIG. 6 . However, the analogous fitting or adaptation would lack components  1 ,  2 ,  3 , and  4 , as previously described. 
         [0037]    By way of providing a detailed description of operation, the following illustration is offered as an example: A diver, before entering the water from a boat or the shore, turns on the device. Upon successfully completing a routine of self diagnostic checks, the control unit recognizes that it is currently at the surface, and inflates the bladder with enough air to ensure the diver will remain at the surface when he enters the water. 
         [0038]    The diver enters the water and, when ready, presses the “down” button. In response the control unit enables the venturi continuously to remove air from the bladder. During this period, the LCD displays the actual depth. Once the descent has begun, the control unit limits the rate of descent to allow the diver to clear the pressure in his ears and otherwise avoid any ill effects of a more rapid descent. 
         [0039]    Once the diver has reached his desired depth, he presses the “Hold” button on the control unit. The control unit attempts to keep the diver at that depth. Should the diver ascend shallower than the preset depth, the controller will decrease buoyancy by venting gas from the BCD so as to place downward force on the diver. Likewise if the diver descends, the controller will increase buoyancy by adding gas to the BCD. However, if the diver&#39;s depth change is oscillatory, such as might arise from the normal cycle of inhaling and exhaling, the controller, after a few such oscillations, will adapt. That is, the controller “senses” that the diver is capable of keeping himself within a range of depth without assistance from the controller. Therefore, the controller will cease compensating for depth changes within the variation of the setpoint established by the diver&#39;s habit. 
         [0040]    The controller adjusts the range over which it will allow the diver to compensate for minor depth changes by the following algorithm: Once a desired depth setpoint has been achieved, the controller retrieves from its memory a stored set of allowed deviations from the programmed setpoint, for example plus three feet and minus five feet. These deviations may be in memory due to values programmed at the time of manufacture of the device, or based on previous behavior of the diver. Should the diver&#39;s excursion from the setpoint exceed the programmed deviation by more than e.g. one foot, the controller will add to or remove air from the bladder so as to return the diver to the intended depth setpoint. However, if the diver, by his own actions such as increasing or decreasing the amount of air in his lungs or swimming upwards or downwards, maintains his depth within the range determine by the controller, the controller will adapt to the capabilities of the diver by increasing the positive or negative deviations allowed. 
         [0041]    Given the exemplary excursion limits just described, should the diver successfully re-establish his desired depth from a depth equal to the setpoint minus five and one half feet, the controller will store a new negative deviation/excursion, of five and one half feet. On the other hand, should the diver fail to control his descent and thus exceed the six foot excursion—that is, the programmed deviation plus one foot buffer—allowed by the controller, the controller will compensate by first adding air to the bladder as previously described and then by reducing the allowed deviation by, for example, one foot. Thus on the next excursion to more than five feet lower than the desired depth, the controller will add air to the bladder, increasing buoyancy so as to move the diver closer to the programmed depth setpoint. A similar example can be made for a positive (upwards) excursion by the diver in excess of the programmed deviation. 
         [0042]    If the diver wishes to change his depth set point beyond the range allowed by the controller, he presses either the “Up” or “Down” button on the control unit. The controller will add or remove gas from the bladder to initiate the change of depth, but then continues to adjust the amount of air in the bladder to control the rate of ascent or descent. During the transition the diver may either swim or remain motionless. In either case, the controller will gently bring him to the desired depth and level off there. Then, the controller will once again allow the diver a degree of vertical movement typically associated with normal breathing. 
         [0043]    As the diver nears the end of the dive, he simultaneously pushes the “Up” and “Hold” buttons. The controller recognizes this as a command to ascend to a depth of 15 feet for a “safety stop,” that is, a typically 3 minute hover at 15 feet for the purpose of safely removing excess nitrogen from the diver&#39;s tissues. The controller adds gas to the BCD bladder to initiate ascent and, once begun, holds the ascent to a safe rate. The controller levels off at 15 feet and maintains equilibrium at that depth for 3 minutes. The controller then signals the completion of the safety stop with an audible and/or visible signal. The diver programs the controller to ascend to zero feet. Again, the controller causes the diver to ascend at a safe rate. Once the surface is reached, gas is added to the bladder to bring the diver&#39;s head fully out of the water. 
         [0044]    The present invention, with the ability to both add and remove air from a bladder under programmed control, is capable of helping a diver prevent or recover from a number of emergency or dangerous situations. As an example, the invention can prevent a diver, during descent, from descending too fast, thus risking ear damage or overshooting his intended depth, the latter instance increasing the risk of nitrogen narcosis, the bends, premature consumption of breathing gases and, ultimately, drowning. 
         [0045]    As a further example, the invention allows a diver to safely ascend to an intended depth in the absence of a tether from a surface which he might grasp to control the rate of his ascent. 
         [0046]    As a further example, the invention assists a diver in maintaining a desired depth while swimming horizontally, especially in the absence of any visual reference points. 
         [0047]    As a further example, the invention helps a diver stay at the desired depth while occupied with a task that diverts attention from maintaining depth equilibrium. For instance, the diver may be examining a portion of a submerged object or the side of a submerged wall, or performing some underwater task. 
         [0048]    As a further example, the invention saves the diver the effort of forcefully swimming lower or higher if he has drifted outside of his ability to regain his set point by inhalation or exhalation. 
         [0049]    As a further example, the invention allows the diver to ascend at a safe rate during an intentional ascent, thereby preventing hazards of uncontrolled ascent such as air embolism or the bends. 
         [0050]    As a further example, the invention enables the diver to surface quickly and safely in an emergency situation. Should the diver wish to surface quickly, he need only press the “Up” button multiple times. The controller, in response and after issuing an audible and/or visible warning, will inflate the bladder so as to carry the diver to the surface rapidly and predictably, slowing just enough to prevent violently propelling the diver through and above the water&#39;s surface.