Abstract:
A control system and method for the seat suspension described herein utilizes a pneumatic cylinder which forms the shock absorber, an air compressor, solenoid valve and a microelectromechanical system (MEMS) based control. In operation, the pneumatic cylinder is filled with a compressible gas and sustained under pressure for the purpose of supporting the static weight of the occupant as well as providing comfort by reducing transmitted vibrations and high acceleration from external disturbances. A control process utilizes vibration data from the MEMS to adjust the gas cylinder pressure accordingly to reduce and damp the undulations of the supported mass.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Application No. 62/026,333, filed Jul. 18, 2014, the disclosure of which is incorporated herein by reference for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    (1) Field of the Invention 
         [0003]    The present invention relates generally to seat suspension systems and more specifically to a pneumatic system with electronic control. 
         [0004]    (2) Description of the Prior Art 
         [0005]    Conventional seat suspension systems use coil springs to absorb transmitted vibration sometimes in conjunction with hydraulic cylinder as dampers. Other suspensions use pneumatic systems that utilize flexible rubber bellows or a rolling diaphragm connected to a separate air reservoir via a flow restriction. In this type of prior art system, the stiffness of the pneumatic spring is determined by the compressed gas pressure and the flow restriction introduces damping. The control system for these devices commonly uses direct pressure measurement of the gas cylinder using conventional pressure gauges or alternatively uses piezoelectric accelerometers which measure g-forces to interpret the vibration experienced by the occupant. Traditional methods of control utilize pressure gauges or piezoelectric accelerometers sensors to infer the vibration data. 
         [0006]    Microelectromechanical system (MEMS) are made up of components generally ranging in size from 20 micrometres to a millimetre. They consist of a central microprocessor unit that processes data and several microsensors components that interact with the surroundings. These microsensors can measure acceleration, yaw, pitch and roll vectors which can be converted into vibration (velocity and displacement) data. 
         [0007]    For safety reasons, the deck of marine crafts are generally kept free from potential tripping hazards. One such hazard often associated with powered boat seats or helm chairs are the exposed power conduits that come out from the pedestal to an electrical outlet. 
         [0008]    Accordingly, a need exists for an improved adaptive pneumatic seat system. Those of skill in the art will appreciate the present invention which addresses the above shortcomings of the prior art. 
       SUMMARY OF THE INVENTION 
       [0009]    Accordingly, it is an object of the present invention to provide an improved seat suspension control system and method for suspending a seat. 
         [0010]    Another object of the invention is to provide a control system and method that permits an electrical connection through the suspension system of the seat. 
         [0011]    Yet another object of the present invention is to provide MEMS to control movement of the seat in addition to a pressure sensor that controls pressure in the cylinder. 
         [0012]    In one possible embodiment, the seat suspension described herein is comprised of a pneumatic cylinder which forms the shock absorber, an air compressor, solenoid valve and a microelectromechanical system (MEMS) based control. In operation, the pneumatic cylinder is filled with a compressible gas and sustained under pressure for the purpose of supporting the static weight of the occupant as well as providing comfort by reducing transmitted vibrations and high acceleration from external disturbances. Pneumatic suspensions inherently have good vibration isolation properties due to the varying spring rate determined by the internal pressure of the gas cylinder. The suspension is activated by charging the cylinder with a compressible gas, preferably air, using an electrically operated on-board compressor. 
         [0013]    In one possible preferred embodiment, the compressed gas inside the cylinder acts as the spring force working against the applied load. When an external disturbance is experienced, the spring force absorbs the transmitted displacement resulting in an increase in internal pressure. The MEMS measure the severity of the disturbance and a control algorithm decides to either allow the cylinder pressure to rise or vent to attenuate the disturbance. A valve relieves just enough pressure inside the cylinder to minimize the impact transmitted to the seat occupant as determined by the control system. 
         [0014]    Accordingly in one embodiment, an adaptive pneumatic seat suspension system may comprise a seat carried by a seat suspension wherein the seat suspension comprises a pneumatic cylinder and a piston reciprocally mounted in the pneumatic cylinder. An air compressor is operatively connected to the pneumatic cylinder. A control is operatively connected to the air compressor to control a pressure in the pneumatic cylinder by adding or releasing pressure. At least one elastic, electrical conductor extends through the piston and cylinder to pass current through the seat suspension. The electrical conductor(s) are coiled to provide the springy elastic property of the coils. In one embodiment, the coiled electrical conductor(s) have a sufficiently high spring constant to apply a significant force urging retraction of the piston in the pneumatic cylinder. 
         [0015]    The system may further comprise a rotatable mounting plate for the seat and an electrical slip ring interconnecting with the elastic electrical conductor(s). The electrical slip ring may comprise conductors in a circular configuration to allow continuous 360 degree rotation of the seat without twisting the elastic electrical conductors. 
         [0016]    The system may further comprise at least one electrically insulated cavity mounted for insulating one or more elastic electrical conductor(s) with respect to each other. 
         [0017]    The system may further comprise microelectromechanical system (MEMS) sensor operatively connected to the control and to the piston to sense changing disturbance conditions based on movement of the piston, such as accelerations, vibrations, and the like. A pressure sensor is operatively connected to the control to sense the pressure in the pneumatic cylinder. The control selects which sensor to weight during operation. 
         [0018]    In one embodiment, the system may further comprise a mounting flange secured to the cylinder. Guide members may be utilized to prevent rotation of the piston with respect to the cylinder. The piston can be connected to a rotary connector for carrying the seat. 
         [0019]    The system may further comprise a piston guide wherein the piston is tubular and encircles the piston guide. The pneumatic cylinder encircles the piston and the piston guide. The piston guide may comprise ball bearings positioned to ride in grooves formed in at least one of the piston or the piston guide. 
         [0020]    In another embodiment, an adaptive pneumatic seat suspension system may comprise a seat suspension comprising a pneumatic cylinder and piston reciprocally mounted in the pneumatic cylinder, a microelectromechanical system (MEMS) sensor operatively connected to the control and to the piston to sense changing disturbance conditions based on movement of the piston; and a pressure sensor operatively connected to the control to sense the pressure in the pneumatic sensor. 
         [0021]    In another embodiment, a method is provided for making an adaptive pneumatic seat suspension system. The method steps may comprise providing a seat carried by a seat suspension, providing that the seat suspension comprises a pneumatic cylinder, providing a piston reciprocally mounted in the pneumatic cylinder, providing an air compressor operatively connected to the pneumatic cylinder, providing a control operatively connected to the pneumatic cylinder to control a pressure in the pneumatic cylinder, providing one or more elastic electrical conductor(s) that extend through the piston and cylinder to pass current through the seat suspension. 
         [0022]    The method may further comprise providing an electrical slip ring interconnecting to the elastic electrical conductor(s) and the seat, and providing that the electrical slip ring comprises conductors in a circular configuration to allow continuous 360 degrees rotation of the seat without twisting cables. 
         [0023]    The method may further comprise providing one or more electrically insulated cavities to form at least a portion of the electrical insulation of the elastic electrical conductor(s). 
         [0024]    The method may further comprise providing a microelectromechanical system (MEMS) sensor operatively connected to the control and to the piston to sense changing disturbance conditions based on movement of the piston, and providing a pressure sensor operatively connected to the control to sense pressure in the pneumatic sensor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention. 
           [0026]      FIG. 1  is a perspective view of a general configuration of a boat seat supported on seat support assembly in accord with a possible embodiment of the invention. 
           [0027]      FIG. 2  is a perspective view of one possible boat seat support assembly accord with a possible embodiment of the invention. 
           [0028]      FIG. 3  is a perspective view, in section, showing a piston and cylinder seat support system with elastic electrical conductors extending therethrough in accord with a possible embodiment of the invention. 
           [0029]      FIG. 4  is a perspective view, in section, showing a pedestal portion of the seat support system with a piston guide in accord with a possible embodiment of the invention. 
           [0030]      FIG. 5  is a perspective view, in partial cross-section, of a piston guide assembly and electrical terminals in accord with a possible embodiment of the invention. 
           [0031]      FIG. 6  is a perspective view, in cross-section, of a piston assembly with elastic electrical conductors hooked to electrical terminals with sufficient force to make electrical contact in accord with a possible embodiment of the invention. 
           [0032]      FIG. 7  is a perspective view, in cross-section, showing indexing grooves to prevent rotation of the piston with respect to the pneumatic cylinder in accord with a possible embodiment of the invention. 
           [0033]      FIG. 8  is a perspective view, in cross-section, showing a rotatable mounting plate and slip ring assembly that allows rotation of the seat without twisting cables in accord with a possible embodiment of the invention. 
           [0034]      FIG. 9  is a schematic diagram of a pneumatic circuit for a boat seat suspension in accord with a possible embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    Detailed descriptions of the preferred embodiment are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or manner. 
         [0036]      FIG. 1  shows a simplified view of a seat  2  attached to the support assembly, shown generally as  1 , of the present invention. 
         [0037]    Referring to  FIG. 1  and  FIG. 2 , the exemplar embodiment presented shows the seat support assembly  1  on which is installed a helm seat  2  of a marine craft. The seat suspension system may also be adopted for other applications where it is desirable to isolate vehicle operators from vibrations transmitted through rigid frame vehicles such as agricultural machinery and earth moving equipment. 
         [0038]    Particularly, seat support assembly  1  illustrates how the suspension assembly is adapted to be inserted into an opening in deck  3  and secured to the deck  3  by the mounting flange  33  operatively attached to pedestal  7  with metal screws  6  or other suitable fasteners. Alternatively, by repositioning of the mounting flange  33  to the base of the bottom cap  5 , the pedestal  7  may be mounted directly on top of the deck. Accordingly, the construction of the pneumatic suspension is generally comprised of a pedestal  7  (see also  FIG. 3 ) preferably anchored to the deck  3  via the mounting flange  33 . 
         [0039]    As best shown in  FIG. 3 , seat support assembly  1  comprises a preferably non-rotating pedestal  7  comprising a reciprocal piston and pneumatic cylinder assembly and an upper rotatable mounting support  9  to which a seat may be attached. 
         [0040]    As shown in  FIG. 3 , reciprocal piston  8  is extended when the chamber  24  is pressurized. The seat  2  of  FIG. 1  is attached to rotatable mounting support  9 . The pneumatic pressure chamber  24  is bounded by the bottom cap  5 , outer sleeve  4 , piston  8  and top cap  21 . Items  16 ,  22  and  23  are seals made from an elastomeric material, O-ring or a mechanical gasket designed to be seated in a groove and compressed to form an effective pressure barrier at their respective interfaces. In one possible embodiment, compressed air enters through port  20  in top cap  21  as described below. An additional air port  27  is provided located in the bottom cap  5  and in one embodiment may be plugged, left open to atmospheric air, filtered air, or other air connector controls. (See  FIGS. 2 and 3 ). However in another embodiment, compressed air may be applied to port  27  to pressurize chamber  24  and port  20  may be left open to atmospheric air, plugged, connected to another air supply, or the like. Other ports may be provided as well. 
         [0041]    In  FIG. 3 , the pedestal  7  is comprised of the mounting flange  33 , collar  18  and outer sleeve  4  which is held together by stud bolts  30  that extend from the collar  18  to the bottom cap  5 . Collar  18  is bolted to flange  33  by cap bolts  17 . Caps  29  may be used to cover the threaded nuts or other fasteners for stud bolts  30 . The piston  8  is arranged concentrically with the annular surface of the outer sleeve  4  and free to translate only in the axial direction. Rotation of the piston  8  is prevented by ball bearings  31  that are nested in machined grooves  39  in piston  8  and keyed with the profiled grooves  58  provided in the piston guide  10  (as shown in  FIG. 7 ). Guide rings  19  for movement along collar  18  and wear rings  15  for movement along outer sleeve  4  allow the piston  8  to glide axially smoothly with minimum friction as well as providing the bearing support to resist lateral and moment loads applied to the seat  2 . Bumper stops  38  made from a shock absorbing material and attached to the bottom of piston  8  cushion piston  8  against a hard impact with the bottom cap  5  when the gas pressure is released. 
         [0042]    In one embodiment, a novel feature presented herein is the method by which electrical power is conveyed from the concealed base of the pedestal to the rotatable end of the extendable cylinder utilizing tension springs. Since all the wires run underneath the deck, the likelihood of slipping, tripping or damaging exposed cords or wires is eliminated. Referring to  FIGS. 4, 5, 6 , wires, cables and piping are generally placed underneath the deck of a marine craft for aesthetic and practical reasons. 
         [0043]    In the embodiment of this seat suspension, the electrical connection is concealed by having the lower electrical terminals  12  protrude out from the bottom end cap  5  of the seat pedestal  7 . Only two terminals are presented in this embodiment representing the positive and negative leads of the direct current power supply. Additional terminals maybe be added as required, as for digital control signals as an example. To prevent a short circuit, these terminals are electrically isolated from each other and from the conductive elements of the pressure cylinder by an insulator  13  as best shown in  FIG. 5 . Seals  14  are functionally configured to maintain the leak tightness of the pressure chamber  24 . An equal number of electrically isolated terminals  35 , aligned concentrically with the terminals on the bottom cap, also penetrate through the top cap  21 . Inside the pressure chamber  24 , an elastically extendible conductive element  11  such as a coiled tension spring is used to make the electrical link between the bottom terminals  12  and concentrically aligned upper terminals  35  on the top cap. Elastically conductive elements  12  are shown connected to upper terminals  35  and extending through piston  8  in  FIG. 6 . 
         [0044]    The elastically conductive elements may hook onto the electrical terminals with hooks  59  to thereby make electrical contact. However, additional screws or the like may be utilized to further induce electrical contact. The extensible nature of the spring  11  allows the piston  8  to be extended and retracted whilst maintaining the electrical continuity between the bottom and top terminals. To prevent an inadvertent electrical short circuit from occurring, the tension springs  11  are inserted in the tubular cavity  56  (See  FIGS. 4 and 5 ) provided in the piston guide  10  (See  FIGS. 3, 4, 5, and 7 ) which is made from a non-conductive material such as plastic. The mechanical energy stored in the spring  11  when extended also aids in retracting the piston  8  when the pressure is removed from the cylinder. It will be understood that electrical conductive, elastomeric plastic elements could be used as well as coiled springs  11 . 
         [0045]    The piston guide  10  illustrated in  FIG. 4  allows the piston  8  to translate axially but prevents rotation by indexing the piston relative to the pedestal. Grooves  58  provided at each corner of the piston guide  10  (See  FIG. 5 ) are engaged with the row of ball bearings  31  (See  FIG. 7 ) fitted into machined groove  39  in piston  8 . This indexes the travelling piston with the pedestal  7  and prevents the conductors  11  from contacting each other. Additional isolation is provided by the tubular cavity  56  which runs the length of the piston guide  10 . As noted, air passageway  32  can be provided for air communication between chamber  24  and port  20 . 
         [0046]    Referring now to  FIG. 8 , from the terminals  35  that penetrate through the top cap  21 , power is delivered to the rotatable seat mounting plate  9  via a rotary electrical connector or stator  25  with slip rings  36  that allow the transmission of power and/or electrical signals from the extendable piston  8  to the rotatable mounting plate  9 . Each conductive ring  36  of stator  25 , which is fixedly attached to the top of piston  8 , is electrically wired to a respective terminal  35 . The rotor  26  is attached to the rotatable mounting plate  9 . It can be seen from  FIG. 8  that as the mounting plate  9  rotates about the axis of the cylinder, electrical contact is maintained by the rotor  26  with the stator  25  via the spring loaded carbon brushes  37  in the rotor. The bearing  28  is a slewing ring or turntable bearing configured to resist the vertical, lateral and moment loads applied at the seat. Support  34  is affixed to piston  8 . Bearing  28  is mounted between fixed position support  34  and rotatable mounting plate  9 . 
         [0047]    Referring to  FIG. 9 , the pneumatic seat suspension control system  50  is comprised of a pneumatic cylinder  24 , an air compressor  43  and control system  49  that monitors the external disturbances and adjusts the cylinder  24  pressure accordingly to minimize the effect of the external disturbances on the occupant. The cylinder  24  may be single acting, as shown in the present embodiment, double acting or telescoping. As discussed above, additional or different air port configurations may be utilized accordingly. In the double acting arrangement. The suspension will have two separate pressure chambers, one for outstroke and the other for instroke. The telescoping or multistage configuration is composed of a series of nested hollow stages wherein each succeeding stage telescopes out as a segmented piston. 
         [0048]    With reference to  FIG. 9 , three way solenoid valve  40  is shown schematically as supplying air to cylinder  24 . In one embodiment, muffler  51  is connected to the exhaust of valve  40  from port  42  as indicated. 
         [0049]    In one embodiment, air from valve  40  can be supplied through port  20  in top cap  21  and travels via a passageway  32  into cylinder  24  (See  FIG. 3 ) In another embodiment, air may be supplied to port  27  or another port (not shown) to be directed into cylinder  24   
         [0050]    The schematic diagram shown in  FIG. 9  illustrates the operation of the suspension system. When the power is turned off, the solenoid valve  40  is inactive, the discharge port  42  is open and the pressure in the cylinder  24  is zero. To activate, the user switches on the power and provides a command input or “ride” setting for the suspension. The ride settings for example may be a designated as “SOFT”, “STANDARD” or “FIRM” mode. A control signal corresponding to the ride mode is sent by the processor to the control circuit which triggers the solenoid to open and power up the air compressor  43 . The pressure rises in the cylinder  24  until the pressure set by the command signal  44  is reached. 
         [0051]    The cylinder pressure is continually monitored by the pressure sensor  41  which sends back an analog signal  45  to the control circuit  49 . The control circuit  49  then compares the feedback signal  45  with the size of the command signal  44  that was provided. If the feedback signal  45  is less than the command signal, current is supplied to the compressor  43  and solenoid valve  40  to raise the pressure in the cylinder  24 . If the feedback signal  45  is greater than the command signal, the compressor  43  is turned off and current is not supplied to the solenoid valve  40  allowing a venting of the pressure in the cylinder  24 . 
         [0052]    In one embodiment, the system is setup for closed loop control. In operation, the piston  8  will oscillate when an external disturbance is applied to the suspension causing the pressure in the cylinder to rise and fall. The control circuit will respond accordingly as previously described, however, the value of the initial command signal  44  is now updated in response to the disturbance. The MEMS sensors  47  attached to the seat measure the accelerations caused by the disturbance and convert it to a digital signal which the processor algorithm evaluates to arrive at an updated command signal  44  for the control circuit  49 . A proportional, integral, derivative (PID) algorithm in the control circuit compares the difference between the command signal  44  with the process signal  45  and decides whether or not to adjust the pressure in the cylinder  24 . Tuning the non-linear system is made by adjusting the PID control parameters (proportional band/gain, integral gain/reset, derivative gain/rate) to the optimum values for the desired control response. 
         [0053]    It will be understood that the invention is not limited to a PID control, or for that matter is not necessarily a closed loop system. Other controllers based on linear control, proportional control; control systems based on fuzzy logic, etc. can be employed. 
         [0054]    It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. 
         [0055]    The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description only. It is not intended to be exhaustive nor to limit the invention to the precise form disclosed; and obviously many modifications and variations are possible in light of the above teaching. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.