Abstract:
A head and neck restraint system includes a headpiece, a saddle, and tensioners connecting the headpiece to the saddle. The headpiece resides on top of a crew member&#39;s head and the saddle includes a saddle strap residing under the crew member&#39;s buttocks. The tensioners are pneumatic muscles which contract when a flow of gas is provided by gas generators. The gas generators are triggered by a G-sensor or by the initiation of a predetermined event. Triggering signals pass through a manifold from an ejection seat, aircraft, or vehicle. Contraction of the pneumatic muscles pulls the headpiece toward the saddle, thereby restraining the head, neck, and spine. The system is worn as an undergarment or incorporated into a garment. A manual adjustment provides head support during flight. The system is particularly useful for preventing head and neck injuries during ejection from or crash of an aircraft or vehicle.

Description:
The present application claims the benefit of U.S. Provisional Application Ser. No. 60/684,014, filed May 23, 2005, which application is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to restraint systems which restrain a crew member body in high dynamic environments, such as during ejection from an aircraft or crash of a vehicle, and in particular to an improved system worn under normal gear for restraint of the head, neck, and spinal column. 
   Head and neck restraint systems have wide application to many injury prone environments including aircraft ejection. Because aircraft ejection presents one of the most complex and challenging environments for a restraint system, the background of the present invention will primarily be described in that context. Clearly, other applications fall within the scope of the present invention. Ejection sequences vary by manufacturer as well as by ejection mode. The ejection mode is related to altitude, airspeed, and in some cases, attitude. Generally, there is a Launch Phase, a Sustainer Rocket Phase, and a Recovery Phase. The following description is highly simplified. 
   The Launch Phase first prepares the seat for ejection by positioning (called haulback) of the crew member&#39;s torso with a ballistic-powered inertia reel. Haulback begins almost simultaneously with ejection initiation, as would head and neck restraint actuation. Next, a ballistic catapult guides the ejection seat upward to a point where there is little or no danger of flame impingement while the seat and crew member are still in the cockpit when the sustainer rocket(s) fire. Seat sensors detect the ejection conditions. All Launch Phase events occur within approximately 180 milliseconds and 39 inches of travel. During the Launch Phase, the crew member is exposed to possible spinal compression injury during initial catapult motion, neck injury from the sudden upward movement, head injury from headrest impact, and a whiplash-type injury from entry into a high-speed airstream. 
   The Sustainer Rocket Phase provides the force to propel the ejection seat away from the aircraft, clearing the empennage, to a height sufficient for successful parachute opening. The seat has selected a mode of operation for the Recovery Phase. The seat and crew member are fully presented to the effects of windblast and no longer connected to the aircraft by the catapult. The seat is free to pitch, roll, and yaw to more dangerous attitudes. During the Sustainer Rocket Phase, the crew member is exposed to possible windblast-related neck and limb injuries as well as spinal injury from dynamic overshoot as the spine extends after the initial compression of the launch phase. 
   The Recovery Phase, which includes parachute deployment and opening, is dependent upon altitude and airspeed. At low altitude and airspeed, the parachute will deploy immediately; at low altitude and high airspeed, the seat will delay parachute deployment until the airspeed is reduced by the drogue parachute; and at very high altitude, parachute deployment will be delayed until the seat and crew member drop to approximately 14,000 feet, descending under a drogue parachute to stabilize the seat/crew member mass. At parachute deployment, the crew member is released from the seat, which falls away. At high speed, inflation of the parachute causes an opening shock, transmitted directly to the crew member&#39;s body, which is free of the ejection seat. After full inflation, the crew member swings down under the parachute canopy and a survival kit deploys. During the Recovery Phase, the crew member is exposed to possible neck and/or spinal injury from the full-body whiplash effects of parachute opening shock. 
   The U.S. government and ejection seat manufacturers have historically recognized a need for a restraint system which reduces or eliminates head and neck injuries during and following aircraft ejection. Secondarily, but still significant, is the concern for spinal injuries. Such a system must meet many challenging requirements. Designing a system to perform within the high dynamic environment of aircraft ejections without radical changes to the ejection system is one challenge. Creating a system which can function in the limited human factors footprint of a high technology cockpit is another. Integrating with the multiple platforms of aircraft, electronics, ejection seat, and personal equipment is another. Accommodating the desires and requirements of pilots and maintenance crews is another challenge. 
   Unfortunately, past concepts have encountered substantial problems of varying types, such as dependency on seat stabilization, protection in one axis while load induction in other axes, major changes to seat design structures or configurations, dependence on the tautness of existing harnesses, inability to withstand high velocity windblast, and/or the lack of crew acceptance. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention resolves the above and other needs by providing a restraint system which addresses head and neck protection during high-speed ejection from an aircraft. The crew member is protected from ejection initiation through parachute opening. A unique aspect of the restraint system according to the present invention is that it is crew worn as a garment. Another feature is that it allows the crew member freedom of movement to perform standard tasks, but has the option of manual adjustment to provide support against head-borne mass. Additionally, the restraint system is capable of interfacing with the seat, aircraft, and/or vehicle in multiple ways, depending on user requirements. 
   The restraint system may be initiated (or triggered) by a variety of triggering methods and/or devices. Two examples of initiation (or triggering) methods/devices are G-sensing and providing a seat signal. Initiation by G-sensing at the onset of the ejection sequence includes the utilization of a sensor which may be man-mounted (for example, integrated into the restraint system, or worn separately), seat mounted, or aircraft mounted, and enables the use of a passive system. Initiation by a seat signal may utilize a signal from an ejection system or may be triggered by seat motion associated with ejection. Seat signal triggering may offer greater reliability and is relatively easy to achieve. Such seat signal may be provided by a direct connection and may be more effective than G-sensing, but also may require an active “hook-up” by the crew member during pre-flight preparation, and such hook-up requirement may be objectionable to the crew member. A seat signal provided using wireless technology is an alternative to a hard wire connection and may overcome crew member objections. The restraint system may respond to other initiation approaches and other triggering devices, and a restraint system as described herein which responds to any triggering device is intended to come within the scope of the present invention. 
   Regardless of the initiation method, the restraint system will appropriately preload the crew member&#39;s spine prior to and/or during catapult stroking of the ejection seat, thus significantly reducing the chance of injurious effects caused by dynamic overshoot. Once activated, the system will restrain the crew member&#39;s head from movement in all axes except negative-Z (e.i., down with respect to the seat). When the head attempts to move radically as a result of high dynamics and accelerations, the system transfers the forces through restraint straps and into the lower torso extremity of the crew member. This consequently reduces potentially harmful head and neck loads. 
   The present invention contemplates optional variations of the baseline design which include: 1) Utilizing an alternate pressure source at selected locations of the restraint system to relieve neck tension during extended operations, which will reduce crew member fatigue and improve crew member endurance; 2) Utilize the basic design to protect rotary-wing crew members from crash or hard-landing loads by sensing impact accelerations or predicted impact, and initiating the restraint system; 3) Utilize the basic design to protect ground vehicle occupants from crash loads by sensing impact accelerations or predicting impacts and initiating the restraint system; and 4) Utilize the basic design to incorporate an upper arm restraint by expanding the restraint system design to capture and restrain the crew member&#39;s arm from the elbow to the shoulder. 
   The present invention redistributes forces which would be otherwise applied to the head, and ultimately the neck. The crew member&#39;s head is restrained by a skullcap or cradle structure having low elastic properties and connected to a harness structure residing about the lower torso much like a parachute harness. When head accelerations (such as during aircraft ejection or vehicle crash) pull the skullcap vertically, side to side, and/or fore and aft, and with the restraint system taut, a percentage of loads is transferred to the lower torso of the crew member. Because the crew member&#39;s mobility should not be affected during normal aircraft operation, substantial “slack” within the harness is preferably provided when the harness is not taut to accommodate the crew member&#39;s movement in the performance of normal missions and maneuvers (i.e., Turning to “check six”). However, prior to or during ejection, the slack in the harness is removed, consequently applying compression from the top of the head through the spine to the load bearing flesh area in the lower extremities. 
   The present invention provides “slack” take-up within the load bearing structure using pneumatic muscle and cold gas generator technology. The system may be activated by the accelerations induced during the catapult-stroking phase of the ejection sequence, by a wireless signal from the seat or vehicle, or by a signal provided by a direct connection to the seat or vehicle. Regardless of the source of the signal, a gas generator sized to the requirements is triggered to activate the pneumatic muscles, thus inducing contraction of the pneumatic muscles resulting in “slack” take-up and crew member compression between the head, shoulders, and lower torso. A saddle type harness is preferred to minimize flesh compression and thus minimize the “slack” take-up requirements. Approximately 4.5 inches of harness take-up is required to transition from normal, comfortable operational fitment of the system to an active restraint effectively limiting head movement. When timely activation of the tensioning device is achieved, an additional advantage associated with spinal pre-compression results. Pre-compressing the spine or upper torso minimizes injurious dynamic overshoot upon and after G loading. 
   Activating the restraint system with the G-load provided by the catapult is practical because there is a significant difference between the crew member&#39;s maximum operational G-load tolerance and the minimum G-load during an ejection. Therefore, the restraint system of the present invention may include a high trigger threshold for sensing the acceleration during ejection to activate the system and thereby avoid false activation during flight maneuvers. Sensing G-loads also allows a system design which does not require a special seat or modifications to existing seats. The trigger threshold relies on the catapult capacity and thrust profile. Preferably, the G-sensor will detect motion and then signal the pressure generator to fire and start inflation of the pneumatic muscle(s), before the ejection seat has moved into the airstream. A G-sensor is a good device for use in a helicopter crash scenario or a ground vehicle crash, but methods with less delay may be the optimum method for use with an ejection seat. Preferably, the gas source provides a gas flow to the pneumatic muscles within 15 milliseconds of the event initiation, and the pneumatic muscles will be substantially full within 30 milliseconds, much like an airbag in an automobile. Again, the pressure device could be triggered with a G-sensitive activator making the system a totally passive system. 
   Activating the subject restraint system with a wireless signal from the seat or vehicle is the least invasive of the preferred methods. Various technology options exist for low-power, miniature signal generators and receivers. Such signal generators, included in the ejection seat timing system, would alert the restraint system receiver of ejection initiation without a direct connection. Direct connections are another method, which requires wiring or tubing as well as a direct hookup between the crew member-worn system and the ejection seat or aircraft. 
   The restraint system according to the present invention includes a pneumatic muscle assembly. The pneumatic muscle assembly preferably contains an inflatable structure enclosed by, bonded to, or integral with a braided mesh sheathing or similar shape-controlling structure. Preferably, one end of the pneumatic muscle has a gas inlet port which attaches to the manifold assembly (described below), and the other end has an attachment for the tension cords (described below). Gas pressure from the manifold assembly enters and expands the inflatable structure. Upon inflation, the braided sheathing allows inflation only in a radial direction, causing the pneumatic muscle assembly to contract (i.e., shorten) and apply tension to restrain the wearer. The configuration of the pneumatic muscle assembly may vary depending on the anthropometric needs of the crew member population, for example, a third percentile female may require a shorter pneumatic muscle with less contraction than a ninety-eighth percentile male. 
   The restraint system may also include self-wicking material, except for the load bearing structure, which is designed to regulate the body temperature by removing perspiration from the surface of the skin. The head and neck protection properties combined with temperature regulation properties provides attractive features to further crew member acceptance of the restraint system. Another embodiment incorporates the head and neck protection system into a flight suit or other garment to avoid an additional layer of equipment. 
   The restraint system according to the present invention further includes a manifold assembly. The configuration of the manifold assembly may vary depending on the source of the initiation signal, for example, either a man- or seat-mounted G-sensor, a direct-connected seat or aircraft signal generator, or a wireless signal from the seat or aircraft. The manifold assembly houses an initiator (or gas generator) assembly and related firing mechanisms, such as a signal receiving device, a battery, wiring, gas port(s), and/or connections to other devices. Upon receiving a signal, the gas generator assembly fires, providing a flow of gas which is routed to the pneumatic muscles. The manifold assembly preferably reduces or eliminates high pressures and high gas temperatures generated by the gas generator assembly against the crew member&#39;s body. The pneumatic muscles are preferably routed through channels in a garment portion of the restraint system. 
   The subject restraint system may further include an option for integrating a manually controlled pressure source which pressurizes specific pneumatic muscles to reduce crew member fatigue caused by head-borne mass. The manually controlled pressure source may be a hand pump or a manually controlled system which utilizes pressure from the G-suit or other pressure source. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The above and other aspects, features, and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
       FIG. 1A  is a front view of a restraint system according to the present invention wherein the restraint is enclosed in a garment and a skull cap. 
       FIG. 1B  is a side view of the restraint system. 
       FIG. 2A  is a front view of the restraint system with the garment and skull cap removed to reveal the components housed within the garment and skull cap. 
       FIG. 2B  is a side view of the restraint system with the garment and skull cap removed to reveal the components housed within the garment and skull cap. 
       FIG. 3A  is a front view of a pneumatic muscle assembly portion of the present invention with a cutaway to reveal the inner components. 
       FIG. 3B  is a side view of the pneumatic muscle depicting the contraction achieved by inflation. 
       FIG. 4  is a schematic view of the manifold assembly portion of the present invention wherein the relationships of several and various embodiments are envisioned. 
   

   Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
   The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
   A front view of a restraint system  10  according to the present invention is shown in  FIG. 1A , and a side view of the restraint system  10  is shown in  FIG. 1B . The restraint system  10  includes a skull cap assembly  11 , a garment assembly  24 , and a harness comprising a saddle assembly  29 . The restraint system  10  provides a flexible and lightweight system which may be worn under flight clothing which restrains the head and neck against ejection seat motion and windblast forces encountered upon initiation of the ejection sequence. The restraint system  10  also restrains the spinal column against dynamic overshoot resulting from ejection seat motion. 
   The skull cap assembly  11  includes the skull cap  12 , a head cradle  13  (see  FIGS. 2A and 2B ) under the skull cap, right front tension cord  14   a,  left front tension cord  14   b,  right rear tension cord  14   c,  and left rear tension cord  14   d  attached to the head cradle  13 , and tension limiters  15   a,    15   b,    15   c,  and  15   d  attached to respective tension cords  14   a - 14   d.  The tension cords  14   a - 14   d  are measured and shortened during initial fitting of the restraint system  10  to the crew member. The length of the tension cords  14   a - 14   d  is sufficient to cover the maximum size in the anthropometric range of the crew member population. 
   The tension limiters  15   a - 15   d  may function as stops to reduce travel of the tension cords  14   a - 14   d,  thereby controlling head alignment. During fitting to the crew member, the tension limiters  15   a - 15   d  are crimped, sewn, or tightened to the tension cords  14   a - 14   d  according to individual anthropometric requirements. Upon system initiation, the tension cords  14   a - 14   d  are retracted until the tension limiter  15   a - 15   d  encounters a grommet  27   a - 27   d  in the garment  25 , thereby limiting the travel of the tension cords  14   a - 14   d.  The retraction force is then transferred to the crew member shoulders through a yoke portion  28  of the garment assembly  24 . The yoke portion  28  is a structural panel across the shoulders, preferably residing on the interior of the garment  25 . The purpose of the yoke  28  is to transfer load to the crew member&#39;s shoulders if the tension limiters  15   a - 15   d  bottom out on the grommets  27   a - 27   d.  The tension limiters  15   a - 15   d  may be used to ensure that excessive force is not exerted on the crew member&#39;s head. Pneumatic muscles  18   a - 18   d  and gas generators  22   a  and  22   b  (see  FIGS. 2A and 2B ) provide tension to the tension cords  14   a - 14   d  and are sized to prevent over tensioning, and the tension limiters  15   a - 15   d  may be used as an added limit on tensioning. 
   The garment  25  is preferably made from fabric and houses tensioner subsystems  16   a,    16   b  (see  FIGS. 2A and 2B ) and may include channels or guides for locating the tensioner subsystems  16   a,    16   b  and the saddle assembly  29  properly about the crew member. The channels or guides may be attached, for example, sewn, in the garment  25  to guide the straps  30   a - 30   b  and restrain the pneumatic muscles  18   a - 18   d,  the manifold assemblies  21   a,    21   b,  and tension cords  14   a - 14   d  preventing them from slipping out of position or off the crew member&#39;s body. In alternative embodiments, a flight suit or anti-G suit could be modified to position the tensioner subsystem  16   a - 16   b  and saddle assembly  29 . 
   The garment assembly  24  incorporates a closure  26 , for example, a zipper or zip-lock device or the like, which enables ease of donning. The garment  25  may be manufactured from a number of modern textiles, preferably soft, thin, breathable, and pliable with wicking characteristics for cooling and transmission of perspiration. In alternative embodiments, the restraint system  10  may also be incorporated into other clothing, such as a flight suit or an anti-G suit. Such alternatives are dependent upon the desires of the users. 
   The saddle assembly  29  attaches to the manifold assemblies  21   a  and  21   b  of the tensioner subsystems  16   a  and  16   b  (see  FIGS. 2A and 2B ). The saddle assembly  29  consists of two side straps  30   a  and  30   b,  one saddle strap  31 , two adjustable connectors  32   a  and  32   b,  and two leg straps  33   a  and  33   b.  The side strap  30   a  connects to the manifold assembly  21   a  and the side strap  30   b  connects to the manifold assembly  21   b.  The side straps  30   a  and  30   b  are adjustable to the crew member. During the one-time fitting process, each side strap (which slides through adjustment slots on the manifold assembly) may be adjusted to the anthropometric needs of the wearer, to provide a comfortable and secure fitment. Excess strap length may be trimmed or stowed accordingly. 
   Each side strap  30   a  and  30   b  connects to opposing sides of the saddle strap  31 . The saddle strap  31  is a wide “U” shaped structural strap which is preferably approximately 1.75 inches wide and preferably forms a flexible seating surface beneath the buttocks which transmits head loads to lower torso extremities of the crew member. The leg straps  33   a  and  33   b  are attached to the base and sides of the saddle strap  31  forming loops around the upper thigh and crotch to preferably prevent the saddle strap  31  from moving on the crew member regardless of the crew member&#39;s posture. Adjustable connectors  32   a  and  32   b  attach to the leg straps  33   a  and  33   b  respectively and enable adjustment of the lengths of the leg straps  33   a  and  33   b  by the crew member. 
   A front view of the restraint system  10  with the garment assembly  24  and skull cap  12  removed to reveal the components housed within the garment assembly  24  and skull cap  12  is shown in  FIG. 2A , and a side view of the restraint system  10  with the garment assembly  24  and skull cap  12  removed to reveal the components housed within the garment assembly  24  and skull cap  12  is shown in  FIG. 2B . The restraint system  10  includes the skull cap assembly  11  which includes a skull cap  12  (see  FIGS. 1A and 1B ), the head cradle  13 , the four tension cords  14   a - 14   d,  and the four tension limiters  15   a - 15   d.  The skull cap  12  is formed to reside over the head cradle  13  and minimize pressure points applied to the head by the head cradle  13 . The skull cap  12  may be manufactured from a number of modern textiles and is preferably soft, thin, breathable, and pliable with wicking characteristics for cooling and transmission of perspiration. The skull cap  12  may be attached to the head cradle  13  or be separate. In alternative embodiments, the skull cap  12  may be eliminated if the customer chooses to attach the tension cords to a helmet or to wear the cradle over an existing crew member&#39;s skull cap. The head cradle  13  resides on the upper portion of the crew member&#39;s head, and when tensioned, restricts the head from moving. The tension cords  14   a - 14   d  connect to the tensioner subsystems  16   a,    16   b  via adjustment fittings  17   a - 17   d  respectively. 
   The tension cords  14   a - 14   d  enter the garment assembly  24  through tension limiter grommets  27   a - 27   d  respectively, which grommets  27   a - 27   d  are built into or attached to the garment assembly  24 . The tension limiters  15   a - 15   d,  one for each tension cord  14   a - 14   d  respectively, are positioned according to the anthropometric requirements of the crew member and secured to the tension cords  14   a - 14   d  above the garment assembly  24  entrance, such that upon activation of the tensioner subsystem  16  the load applied to the head and neck is controlled. Further, upon activation of the tensioner subsystems  16   a,    16   b,  the tension limiter grommets  27   a - 27   d  transfer the remaining load applied by the tensioner subsystems  16   a,    16   b  from the head into the torso through the yoke  28  (see  FIGS. 1A and 1B ). The torso load, dictated by the placement of the tension limiters  15   a - 15   d,  is distributed across the shoulders of the crew member by the yoke  28  built into the garment assembly  24 . 
   The restraint system  10  includes a right tensioner subsystem  16   a  and a left tensioner subsystem  16   b.  The tensioner subsystems  16   a  and  16   b  include adjustable fittings  17   a - 17   d,  pneumatic muscle assemblies  18   a - 18   d,  port connectors  20   a - 20   d,  manifold assemblies  21   a  and  21   b,  and gas generators  22   a  and  22   b.  The manifold assemblies  21   a  and  21   b  house or connect to the gas generators  22   a  and  22   b.    
   The manifold assemblies  21   a  and  21   b  receive and route a flow of gas through a filter  42  (see  FIG. 4 ) and to the pneumatic muscle assemblies  18   a - 18   d.  The filter  42  slows the speed of the expanding gas and removes particulates from the gas. Alternate embodiments of the manifold assembly  21  may include provisions for 1) a button-type battery  43  or a connection to an external power source, 2) a G-sensor  44  or a wireless communications receiving device  45 , 3) a connection  47  for manual pressurization/depressurization, 4) a device for relieving gas pressure  47  from the system after parachute opening, and/or other such devices. The outlet port for the flow of gas includes a fitting for connection to the pneumatic muscle(s)  18   a - 18   d.  The manifold assemblies  21   a  and  21   b  also provide for attachment to and/or adjustment  48  of the side straps  30   a  and  30   b  on the saddle assembly  29 . 
   The manifold assemblies  21   a  and  21   b  are a sealed environment to prevent pressurized gas from escaping and coming into contact with the crew member&#39;s body. The gas generators  22   a  and  22   b  are preferably cool gas generators and the burn rate of the gas generators  22   a  and  22   b  will preferably be selected to reduce heat production to an acceptable level. Initial heat produced by the generation of the gas flow will be reduced by the filter and conducted to the manifold mass. The gas generators  22   a  and  22   b  are similar to an automobile airbag gas generator, which generates some heat, but remains cool to the touch. Channels or pockets for retaining the tensioner subsystems  16   a  and  16   b  in the garment portion  24  provide additional protection from heat and by the time the pressure is released from the system, any excessive heat will have been dissipated. 
   The tensioner subsystems  16   a  and  16   b  are attached to the skull cap assembly  11  by the adjustable fittings  17   a - 17   d.  The tensioner subsystem  16   a  includes the two adjustment fittings  17   a  and  17   c  and the tensioner subsystem  16   b  includes the two adjustment fittings  17   b  and  17   d.  The adjustment fittings  17   a - 17   d  connect to the tension cords  14   a - 14   d  respectively. 
   The gas generators  22   a  and  22   b  preferably use a chemical reaction system initiated by a mechanically, ballistically, or electrically initiated gas generator, similar to an automobile airbag gas generator. The preferred chemical reaction produces a cool gas which rapidly expands to fill the available space, which space in the case of the present invention is provided by the pneumatic muscles  18   a - 18   d.  The burn rate of the gas generators  22   a,    22   b  is limited to minimize heat generation. The pneumatic muscles  18   a - 18   d  and the gas generators  22   a,    22   b  are preferably sized to preclude over pressurizing the system, although other means may be exercised to prevent over pressurizing. 
   The right front pneumatic muscle assembly  18   a  connects between the adjustable fittings  17   a  and the port connector  20   a,  the left front pneumatic muscle assembly  18   b  connects between the adjustable fittings  17   b  and the port connector  20   b,  the right rear pneumatic muscle assembly  18   c  connects between the adjustable fittings  17   c  and the port connector  20   c,  and the left rear pneumatic muscle assembly  18   d  connects between the adjustable fittings  17   d  and the port connector  20   d.  The port connectors  20   a  and  20   c  are connected to the right manifold assembly  21   a  and the port connectors  20   b  and  20   d  are connected to the left manifold assembly  21   b.    
   The right gas generator  22   a  is connected to the right manifold assembly  21   a,  and the left gas generator  22   b  is connected to the left manifold assembly  21   b.  The gas generators  22   a  and  22   b  provide a flow of gas which activates the restraint system  10 . The gas generators  22   a  and  22   b  may be triggered by a built-in G-sensor or by an external signal, for example, from the crew member seat or vehicle, in other embodiments. When triggered, the gas generators  22   a  and  22   b  provide a gas flow through the manifold assemblies  21   a  and  21   b,  which directs the flow into a pressure vessel of the front and back pneumatic muscles  18   a - 18   d.  The pneumatic muscles  18   a - 18   d  consequently inflate and contract, thus tensioning and activating the restraint system  10 . A support adjustment source  23  may be connected to the manifold assemblies  21   a  and  21   b  to provide the crew member with an option of inflating selective pneumatic muscles  18   a - 18   d  to improve comfort and/or reduce fatigue on the neck caused by an unbalanced helmet weight over time. The source of gas may be a hand pump/bulb for ambient air, a separate pressurized tank, or a tap onto the anti-G suit or other acceptable source which would tension the pneumatic muscles  18   a - 18   d.  The particular source is dependent on the customer&#39;s needs. 
   A detailed view of the pneumatic muscle  18   a  in a relaxed state is shown in  FIG. 3A , and a detailed view of the pneumatic muscle  18   a  in an inflated state is shown in  FIG. 3B . The pneumatic muscles  18   b - 18   d  are preferably similar to the pneumatic muscle  18   a,  but the pneumatic muscles  18   c  and  18   d  (the rear pneumatic muscles) may be different from the pneumatic muscles  18   a  and  18   b  (the front pneumatic muscles), for example, may have a different length or a different percentage contraction. The pneumatic muscles  18   a - 18   d  preferably comprise four basic components: a braided mesh sheathing  36 ; a bladder  35  located inside the sheathing  36  that is capable of expanding when pressurized; the adjustment fitting  17   a  on one end of the pneumatic muscle  18   a,  and a port connector  20   a  on an opposite end of the pneumatic muscle  18   a.  Upon pressurization, the bladder  35  expands forcing the sheathing  36  to increase in diameter and shorten from a relaxed length L 1  to an inflated length L 2 . The shortening length L 2  may be shortened by as much as approximately 40 percent of the relaxed length L 1  (i.e., L 2  may be as small as approximately 0.60 times L 1 ). The adjustment fitting  17   a  and the port connector  20   a  on the pneumatic muscle  18   a  cause attached items to be drawn together by the retraction, providing a strong tensioning element in a small simple device which will function when twisted or curved. The port connector fitting  20   a  also serves as a passage for the pressurizing gases. 
   A diagram of the manifold assembly  22   a  and a generic seat  60  of the present invention is shown in  FIG. 4 , wherein alternative elements are described. The manifold assembly  21   b  is generally similar to the manifold assembly  21   a.  The manifold assembly  21   a  may be designed to receive electrical or pressure signals  66  via a direct connection port  46  or to receive wireless signals  62  via a receiver  64 , depending on the capabilities of the seat, vehicle, or customer requirements. The seat  60  may produce signals from 1) an electronic sequencer  68  transmitted via a wireless communications device  49 , 2) an electronic sequencer  68  transmitted via direct electrical or pressure signals  66 , 3) a gas pressure or electrical signal device  50  transmitted via direct electrical or pressure signals  66 , and/or 4) an on-seat G-sensor  51  transmitting signals via direct electrical or pressure signals  66 ; and for vehicle crash situations, a signal may be produced by 5) a vehicle-mounted G-sensor  52  transmitted via direct electrical or pressure signals  66 . Clearly, a combination of signal sources may be employed, depending on customer design requirements. Within the manifold assembly  21   a,  a wireless signal  62  would be processed by a signal processor  45  to fire the gas generator  22   a,  with supplemental power from a battery  43  if needed. A signal from a G-sensor  44  within the manifold assembly  21   a  would be processed by a signal processor  45  to fire the gas generator  22   a,  with supplemental power from a battery  43  if needed. An electrical signal  66  received by direct connection  46  would either be processed by the signal processor  45  or would immediately fire the gas generator  22   a,  depending on design requirements. Finally, a gas pressure signal  66  received by direct connection  46  would either be processed by the signal processor  45  or would immediately fire the gas generator  22   a.  An outlet port  41  is provided for connecting to the port connector fittings  20   a - 29   d  (see  FIGS. 2A and 2B ). 
   Continuing with  FIG. 4 , the gas generator  22   a  is shown residing in the manifold assembly  21   a.  The gas generator  22   a  may also be attached to the exterior of the manifold assembly  21   a,  or be connected by tubing to the manifold assembly  21   a.  A filter  42  filters gasses generated by the gas generator  22   a  prior to entry into the pneumatic muscle  18   a  or  19   c.  A pressure relief/support adjustment port  47  allows regulation of the gasses provided by the gas generator  22   a  to the pneumatic muscle  18   a - 18   d.  A G-sensor  44  may be included in the manifold assembly  21   a  to detect the ejection event, and to trigger the gas generator  22   a.    
   In a first alternative embodiment of the restraint system  10 , the support adjustment source  23  provides adjustable inflation pressure from outside source(s) to tension selected pneumatic muscles to support the head against head-borne mass. In a second alternative embodiment of the restraint system  10 , the direct input connector  46  provides direct interface with the aircraft or ejection seat for precise timing of gas generator  22   a  and  22   b  initiation within the ejection sequence. In a third alternative embodiment of the restraint system  10 , portions of the restraint system may be incorporated into other flight gear, such as a flight suit, jump suit, pressure suit, vest assembly, or similar garment. Additionally, a fourth alternative embodiment of the restraint system may include an upper arm restraint which is an optional use of the existing pneumatic muscle retraction of the tension cords. Such supplemental retraction of the upper arm or elbow of a flight suit or other garment may be used to restrain the arms against limb abduction during high-speed windblast, and may be provided dependent upon the desires and needs of the crew members. 
   While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.