Patent Publication Number: US-2023150670-A1

Title: Restraint System Utilizing Co-Axial Actuation

Description:
FIELD 
     The present disclosure is directed to cargo restraint systems and, more particularly, to a cargo restraint system capable of coaxial actuation of restraints. 
     BACKGROUND 
     Many aircraft have at least one cargo bay designed to receive cargo. Such cargo bays include cargo loading systems that include rollers located on a floor of the cargo bay to provide conveyance for moving a unit load device (ULD) or other cargo through the cargo bay. After cargo has been loaded into the cargo bay, it may be desirable to restrain the cargo. Some ULDs, for example, military pallets, have pockets along the sides of the pallets. Restraints may be located in the pockets to provide longitudinal and/or lateral restraint. Such restraint reduces the likelihood of cargo shifting relative to the cargo bay during taxi, takeoff, flight, and landing. Current restraint actuation systems are generally configured to deploy and to stow all the restraints simultaneously. Such actuating scheme tends to limit the number of available cargo load configurations. 
     SUMMARY 
     In various embodiments, a restraint assembly actuation system for use with a cargo restraint system is provided comprising a drive shaft assembly comprising a first outer tube and an inner shaft, wherein the first outer tube and the inner shaft are disposed coaxially about an axis and a first restraint coupled to the first outer tube, wherein the first outer tube is configured to rotate the first restraint about the axis to a raised position to restrain a cargo load. 
     In various embodiments, the first restraint comprises a head configured to engage with the cargo load. 
     In various embodiments, the first restraint comprises a shroud coupled to the outside of the first outer tube, and a plunger rod coupled to the shroud and the head. 
     In various embodiments, the shroud comprises a notch opening configured to receive a notch coupled to the inner shaft and the shroud at a first opening of the first outer tube. 
     In various embodiments, the first restraint further comprises the head defining a plunger channel, a plunger including the plunger rod and a plunger lever, the plunger rod being located, at least, partially in the plunger channel, a plunger torsion spring configured to apply a first biasing load to the plunger lever, and a compression spring configured to bias a first end of the plunger away from an upper surface of the head. In various embodiments, a drive cap located around the first end of the plunger rod. In various embodiments, the shroud defines a plunger opening configured to receive the first end of the plunger rod. In various embodiments, the shroud includes a protrusion extending radially outward from an outer circumferential surface of the shroud. In various embodiments, a second outer tube is coupled to the inner shaft and configured to rotate with the inner shaft. In various embodiments, a second restraint is coupled to the second outer tube, wherein the second outer tube is configured to rotate the second restraint about the axis to a raised position to restrain the cargo load. In various embodiments, the second outer tube is located aft of the first outer tube. 
     In various embodiments, a coaxial actuator assembly is provided comprising a drive shaft assembly comprising a first outer tube and an inner shaft, wherein the first outer tube and the inner shaft are disposed coaxially about an axis, a first outer tube actuator assembly coupled to the drive shaft assembly, a first actuator tube disposed within the first outer tube actuator assembly and coupled to the first outer tube, wherein the first actuator tube comprises a first actuator opening and a second actuator opening, each disposed in the first actuator tube, a first spring loaded plunger configured to be disposed in at least one of the first actuator opening or the second actuator opening, and a first actuator lever coupled to the first spring loaded plunger, the first actuator lever configured to translate the first spring loaded plunger at least one of in and out the first actuator opening and the second actuator opening, and a first geometric gripping surface coupled to the first outer tube actuator assembly configured to drive rotation of the first outer tube. In various embodiments, the first outer tube rotates coaxially about the axis in response to the first geometric gripping surface driving rotation of the first outer tube. In various embodiments, an inner shaft actuator assembly is coupled to the drive shaft assembly, a second actuator tube disposed within the inner shaft actuator assembly and coupled to the inner shaft, wherein the second actuator tube comprises a first actuator opening and a second actuator opening each disposed in the second actuator tube, a second spring loaded plunger configured to be disposed in the first actuator opening or the second actuator opening, and a second actuator lever coupled to the second plunger, configured to translate the second plunger at least one of in and out the first actuator opening and the second actuator opening, and a second geometric gripping surface coupled to the inner shaft actuator assembly and configured to drive rotation of the inner shaft. In various embodiments, the inner shaft rotates in response to the second geometric gripping surface driving rotation of the inner shaft. 
     In various embodiments, a restraint assembly actuation system is provided comprising a drive shaft assembly comprising a first outer tube and an inner shaft, wherein the first outer tube and the inner shaft are disposed coaxially about an axis, a coaxial actuator assembly comprising a first outer tube actuator assembly coupled to the drive shaft assembly, a first actuator tube disposed within the first outer tube actuator assembly and coupled to the first outer tube, wherein the first actuator tube comprises a first actuator opening and a second actuator opening each disposed in the first actuator tube, a first spring loaded plunger configured to be disposed in at least one of the first actuator opening or the second actuator opening, a first actuator lever coupled to the first spring loaded plunger, configured to translate the first spring loaded plunger at least one of in and out the first actuator opening and the second actuator opening, and a first geometric gripping surface coupled to the first outer tube actuator assembly and configured to drive rotation of the first outer tube, a second outer tube coupled to the inner shaft, and a first restraint assembly actuation system comprising a first restraint coupled to the first outer tube, wherein the first outer tube is configured to rotate the first restraint about the axis to a raised position to restrain a cargo load. In various embodiments, a second restraint is coupled to the second outer tube. In various embodiments, the second outer tube is configured to rotate the second restraint about the axis to the raised position to restrain the cargo load. In various embodiments, an inner shaft actuator assembly is coupled to the drive shaft assembly, a second actuator tube disposed within the inner shaft actuator assembly and coupled to the inner shaft, wherein the second actuator tube comprises a first actuator opening and a second actuator opening each disposed in the second actuator tube, a second spring loaded plunger configured to be disposed within at least one of the first actuator opening or the second actuator opening, and a second actuator lever coupled to the second plunger, configured to translate the second plunger at least one of in and out the first actuator opening and the second actuator opening, and a second geometric gripping surface coupled to the inner shaft actuator assembly configured to drive rotation of the inner shaft. In various embodiments, a plurality of forward restraints is coupled to the first outer tube and configured to be actuated by the first outer tube, and a plurality of aft restraints coupled to the second outer tube and configured to rotate coaxially with the second outer tube. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated herein otherwise. These features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosures, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements. 
         FIG.  1    illustrates an aircraft being loaded with cargo, in accordance with various embodiments; 
         FIG.  2    illustrates a portion of an aircraft cargo deck having a cargo restraint system, in accordance with various embodiments; 
         FIG.  3    illustrates a portion of the cargo restraint system of  FIG.  2   , in accordance with various embodiments; 
         FIGS.  4 A and  4 B  illustrate a first restraint of a restraint assembly actuation system for use with the cargo restraint system of  FIG.  2   , in a raised position and a stowed position, respectively, in accordance with various embodiments; 
         FIGS.  5 A and  5 B  illustrate the first restraint of the restraint assembly actuation system for use with the cargo restraint system of  FIG.  2   , in the raised position, in accordance with various embodiments; 
         FIG.  6    illustrates a cross-section view of the first restraint of the restraint assembly actuation system for use with the cargo restraint system of  FIG.  2   , in the raised position, with the cross-section taken along the line  6 - 6  in  FIG.  5 B ; 
         FIGS.  7 A,  7 B,  7 C,  7 D and  7 E  illustrate a cross-section view of the first restraint of the restraint assembly actuation system for use with the cargo restraint system of  FIG.  2   , taken along the line  6 - 6  in  FIG.  5 B  as the first restraint translates from the raised position to the stowed position, in accordance with various embodiments; 
         FIG.  8    illustrates a cross-section view of the second restraint of the restraint assembly actuation system for use with the cargo restraint system of  FIG.  2    taken along the line  6 - 6  in  FIG.  5 B ; 
         FIG.  9    illustrates a coaxial actuator assembly, in accordance with various embodiments; 
         FIG.  10    illustrates a cross-section view of a first outer tube actuator assembly of the coaxial actuator assembly in  FIG.  9   ; 
         FIG.  11    illustrates a cross-section view of an inner shaft actuator assembly of the coaxial actuator assembly in  FIG.  9   ; and 
         FIG.  12    illustrates a restraint assembly actuation system, in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration and their best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the spirit and scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. 
     The present disclosure provides a restraint assembly actuation system for aircraft cargo that, in various embodiments, utilizes a coaxial actuator assembly to actuate (e.g., using any appropriate motion or combination of motions) one or more restraints from a raised (or deployed) position to a stowed position. In accordance with various embodiments, the restraint assembly actuation system includes a drive shaft assembly comprising a first outer tube and an inner shaft disposed coaxially about an axis. In various embodiments, the inner shaft can be another tube and not a solid shaft. Multiple tubes may be disposed in the system coaxially about the axis without a solid inner shaft. In various embodiments, a first restraint or a plurality of first restraints may be coupled to a first outer tube. The cargo restraint system, in various embodiments, also comprises one or more coaxial actuator assemblies. A coaxial actuator assembly, in various embodiments, comprises a first outer tube actuator assembly coupled to the drive shaft assembly. The first outer tube actuator assembly, in various embodiments, controls rotation of the first outer tube located about the axis. Translation of the first restraint or a plurality of first restraints may be controlled by rotation of the first outer tube. 
     In accordance with various embodiments, a coaxial actuation assembly may comprise an inner shaft actuator assembly configured to control rotation of the inner shaft. At or near an aft end of the inner shaft, in various embodiments, an extender tube may be coupled to the inner shaft. A second outer tube may be coupled to the inner shaft at the extender tube, such that rotation of the inner shaft is translated to the second outer tube. Translation of a second restraint or a plurality of second restraints may be controlled by rotation (e.g., actuation) of the second outer tube. Allowing the restraints to be actuated as in at least two groups allows for more flexible control options than a single actuation system that actuates all restraints at once, while increasing the number of available restraining configurations throughout the cargo deck. 
       FIG.  1    illustrates an aircraft  20  with cargo  22  being loadable through a loading door  24  of the aircraft  20 . Cargo  22  may be loaded through loading door  24  and onto a cargo deck  26 .  FIG.  2    illustrates cargo deck  26 . An X-Y-Z axis is shown in various drawings to illustrate various orientations of components. Cargo deck  26  includes a cargo deck floor  30 , which may be formed by one or more panels  32  that are coupled to various structural components of aircraft  20  (e.g., to beams, floors, etc.). 
     In accordance with various embodiments,  FIG.  2    illustrates cargo deck  26  includes a restraint assembly actuation system  50 . Stated differently, restraint assembly actuation system  50  may be installed along cargo deck  26 . Cargo deck  26  may also include a cargo loading system  60  comprising a plurality of freely rotating conveyance rollers and/or powder drive units (PDUs) mounted in the cargo deck  26  to define the conveyance plane. Cargo loaded onto the aircraft cargo deck  26  can be moved throughout the cargo deck  26  using the cargo loading system  60 . 
     Restraint assembly actuation system  50  may be used to restrain cargo (e.g., unit load devices (ULDs)) within/relative to the cargo deck  26 . The restraint assembly actuation system  50  may include a plurality of first restraints  102   a , one or more second restraints  104 , and a plurality of third restraints  106 . In various embodiments, the first restraints  102  may be referred to as X-restraints as they may restrict cargo from translating in the X (or longitudinal) direction. The second restraints  104  may be referred to as Z-restraints as they may restrict cargo from translating in the Z (e.g., vertical) direction. The third restraints  106  may be referred to as YZ-restraints as they may restrict translation of cargo in the Z (e.g., vertical) direction and the Y (e.g., lateral) direction. However, one skilled in the art will realize that the restraints  102 ,  104 ,  106  may be used to restrain cargo in any other directions (e.g., the first restraints  102  may restrain cargo in the Y direction). The restraint assembly actuation system  50  may include a coaxial actuator assembly  110 . A control region  112  of coaxial actuator assembly  110  may be located, for example, proximate loading door  24 , a forward end of the aircraft, and/or at any other location that may be readily accessible to crew responsible for loading cargo into cargo deck  26 . As described in further detail below, various components of coaxial actuator assembly  110  may be located under panels  32 . Coaxial actuator assembly  110  is configured to control the actuation of the first restraints  102 . In this regard, coaxial actuator assembly  110  may be employed to translate first restraints  102  between a raised position and a stowed position. In various embodiments, coaxial actuator assembly  110  may also control actuation of the second restraints  104  and/or the third restraints  106 . 
       FIG.  3    illustrates how the various restraints of restraint assembly actuation system  50  may restrain a ULD  114 . As shown, the first restraint  102  may rest between tabs  116 ,  118  of the ULD  114 , restricting movement of the ULD  114  in the X direction. The second restraint  104  may rest above tabs  107 ,  109  of the ULD  114 , thus restricting movement of the ULD  114  in the Z direction. The third restraint  106  may rest adjacent and above the tab  118  of the ULD  114 , thus restricting movement of the ULD  114  in the Y and Z directions. 
     Referring now to  FIG.  4 A  and  FIG.  4 B , additional details of a first restraint  102  are shown. As shown, first restraint  102  may be actuated between a raised position (as shown in  FIG.  4 A ) and a stowed position (as shown in  FIG.  4 B ). First restraint  102  may include a head  120  (also referred to herein as a restraint body) which may be both raised and stowed. In the raised position, the head  120  may extend above the cargo deck floor  30 . In the stowed position, the head  120  may fit within an orifice  122  formed in the cargo deck floor  30 . For example, panel  32  may define an orifice  122  configured to receive a head  120 . In the stowed position, a first surface  124  of head  120  may be relatively/substantially flush and/or planar with an upper surface  36  the panel  32 . 
     With momentary reference to  FIG.  12   , restraint assembly actuation system  50  is further illustrated. Restraint assembly actuation system  50  comprises first group  360  of restraints  102   a  and second group  362  of restraints  102   b . Restraint assembly actuation system  50  further comprises drive shaft assembly  150 . Drive shaft assembly  150  comprises inner shaft  154  and first outer tube  152 , which are coaxially disposed as described herein along axis A-A′, with A representing the forward terminus of drive shaft assembly  150  and A′ representing the aft terminus of drive shaft assembly  150 . Coaxial actuator assembly  110  is illustrated comprising inner shaft actuator assembly  976  and first outer tube actuator assembly  975 . Inner shaft  154  is coupled to inner shaft actuator assembly  976 , where inner shaft actuator assembly  976  is configured to rotate inner shaft  154  about axis A-A′. First outer tube  152  is coupled to first outer tube actuator assembly  975 , where first outer tube actuator assembly  975  is configured to rotate first outer tube  152  about axis A-A′. 
     First outer tube  152  is configured, as shown and described herein, to actuate restraints  102   a . In that regard, rotation of first outer tube  152  imparted by first outer tube actuator assembly  975  causes actuation of restraints  102   a . Restraints  102   b , however, remain stationary and are thus not activated by rotation of first outer tube  152  imparted by first outer tube actuator assembly  975 . Rotation of inner shaft  154  imparted by inner shaft actuator assembly  976  causes actuation of restraints  102   b . In that manner, first group  360  are separately actuated from second group  362 . Stated another way, restraint assembly actuation system  50  allows one group of restraints to be actuated independently of a second group of restraints. 
     In various embodiments, first outer tube  152  terminates along axis A-A′. Inner shaft  154  may be coupled to second outer tube  352 . Second outer tube  352  may be fixedly attached to inner shaft  154  such that rotation of inner shaft  154  rotates second outer tube  352 . In that regard, in various embodiments, inner shaft  154  rotates an extender tube such that second outer tube  352  rotates one revolution for every one revolution rotated by inner shaft  154 . Second outer tube  352  may be fixedly attached to inner shaft  154  by any suitable means, for example, by press fit, interference fit, fasteners, threaded engagement, radially disposed pins, and/or welding, brazing, or other metallurgical joinery. Second outer tube  352  may be coupled to inner shaft  154  via intermediary components, such as a collar or cylindrical clamp. 
     With reference to  FIG.  5 A  and  FIG.  5 B , first restraint  102  is illustrated in the raised position. In  FIG.  5 B , panel  32  is removed to illustrate components of restraint assembly actuation system  50  that may be located under upper surface  36  of panel  32 . In various embodiments, first restraint  102  may include one or more roller(s). Rollers may protrude from side surfaces  132  of head  120 . Rollers may be spring loaded such that rollers retract into head  120 , against the bias of a spring, in response to a load (represented by arrow L 1 ) being transmitted from ULD  114  into the roller and consequently first restraint  102 . First restraint  102  may be raised into (e.g., located within) a pocket  117  of ULD  114 . Pocket  117  may be defined by a flange  119  located about a perimeter of ULD  114 . In embodiments, load L 1  may be transmitted from ULD  114  into first restraint  102 . The rollers may reduce friction between ULD  114  and first restraint  102  when first restraint  102  translates between the raised position (as shown in  FIG.  4 A  and  FIG.  5 A ) and the stowed position (as shown in  FIG.  4 B ). In this manner, first restraint  102  may allow for lower release forces when moving from the raised position to the stowed position to release ULD  114 . Stated differently, forces reacting between ULD  114  and first restraint  102  are attenuated by the rollers to increase ease of movement of first restraint  102  (relative to ULD  114 ) when moving between the raised position and the stowed position. 
     A mount  140  ( FIG.  5 B ) may be coupled to panel  32  via fasteners  142 . Fasteners  142  can be washers and a bolt head, or any other suitable fastener. In accordance with various embodiments, a drive shaft assembly  150  may be located through, and may extend through, mount  140  and head  120 . Stated differently, mount  140  and head  120  may be located on, and/or mounted on, drive shaft assembly  150 . Mount  140  may be a stationary structure. Head  120  and drive shaft assembly  150  may rotate relative to mount  140 . Drive shaft assembly  150  includes a first outer tube  152  and an inner shaft  154 . First outer tube  152  is located about inner shaft  154  (e.g., first outer tube  152  and inner shaft  154  are coaxially disposed). In accordance with various embodiments, first outer tube  152  and inner shaft  154  may both coaxially rotate about an axis A-A′. However, first outer tube  152  rotates independently of inner shaft  154 . In this regard, rotation of inner shaft  154  may be performed independently from first outer tube  152  (i.e., rotation of inner shaft  154  does not cause or impart rotation/movement of first outer tube  152 ) and rotation of first outer tube  152  may be performed independently from inner shaft  154  (i.e., rotation of first outer tube  152  does not cause or impart rotation/movement of inner shaft  154 ). 
     In various embodiments, a lubricant may be applied to the outside of the inner shaft to reduce friction between the first outer tube and the inner shaft. The lubricant may comprise oil or grease. In various embodiments, the outside of the inner shaft or the inside of the first outer tube may be coated in polytetrafluoroethylene to reduce friction between the first outer tube and the inner shaft. In various embodiments, the inner shaft and/or the first outer tube may comprise a wear coating disposed on one or more surfaces to provide corrosion resistance and/or mitigation of friction or abrasion. 
     First restraint  102  may include one or more head torsion spring(s)  160 . Head torsion spring  160  is configured to bias head  120  toward the raised position or the stowed position. Stated differently, head torsion spring  160  is configured to bias head  120  in a first circumferential direction about axis A-A′. As described in further detail below, first restraint  102  includes a plunger  170  ( FIG.  6   ), which may engage first outer tube  152 , such that rotation of first outer tube  152  is transferred to head  120 . Stated differently, when the plunger  170  is in an engaged state, head  120  rotates with first outer tube  152 . 
     With reference to  FIG.  6   , a cross-section view of first restraint  102 , taken along line  6 - 6  in  FIG.  5 B , is illustrated. In accordance with various embodiments, first restraint  102   a  includes a plunger  170 . In  FIG.  6   , first restraint  102  is in the raised position and plunger  170  is in an engaged state. Plunger  170  includes a plunger rod  172  and a plunger lever  174 . Plunger rod  172  is configured to translate radially (i.e., perpendicular to axis A-A′). In this regard, plunger rod  172  translates toward and away from first outer tube  152 . In various embodiments, plunger rod  172  may located in a plunger channel  176  defined by head  120 . A compression spring  180  may be located about plunger rod  172 . Compression spring  180  may be compressed between a spring interference surface  182  of plunger rod  172  and a bushing  184  located about plunger rod  172 . In various embodiments, bushing  184  may be eliminated and compression spring  180  may be compressed between spring interference surface  182  of plunger rod  172  and a second spring interference formed by head  120 . Compression spring  180  biases a first end  186  of plunger rod in the radially inward direction (i.e., toward first outer tube  152  and axis A-A). 
     A pin  188  may be located through plunger rod  172  and plunger lever  174 . Pin  188  may be located proximate a second end  190  of plunger rod  172 . Second end  190  is opposite first end  186 . Plunger lever  174  may rotate about pin  188 . A plunger torsion spring  192  may be located about pin  188  and may apply a biasing load to plunger lever  174 . Plunger torsion spring  192  may bias plunger lever  174  in the first circumferential direction about pin  188 . 
     In accordance with various embodiments, a shroud  200  may be located about first outer tube  152 . Stated differently, an inner circumferential surface  202  of shroud  200  may define a tube channel configured to receive first outer tube  152 . In accordance with various embodiments, a plunger opening  206  is formed in the outer circumferential surface  208  of shroud  200 . Stated differently, shroud  200  defines plunger opening  206 . Plunger opening  206  is configured to receive first end  186  of plunger rod  172 . Locating plunger rod  172  in plunger opening  206  creates an interference between plunger rod  172  and shroud  200 , such that plunger rod  172  is prevented from translating relative to shroud  200 . In accordance with various embodiments, shroud  200  defines a notch opening (e.g., a bore)  210  configured to receive a notch  212 . First outer tube  152  may define a notch channel  214 . Notch  212  may be located through notch opening  210  and in notch channel  214 , in response to radially aligning notch opening  210  and notch channel  214 . Locating notch  212  in notch opening  210  and notch channel  214  rotationally couples shroud  200  and first outer tube  152 , such that rotation of first outer tube  152  about axis A-A′ causes shroud  200  to rotate about axis A-A′. Inner shaft  154  is shown extending through axis A-A′, axis A-A′ being the common axis for both first outer tube  152  and inner shaft  154 . 
     Shroud  200  includes a protrusion  220 . Protrusion  220  extends radially outward from outer circumferential surface  208  of shroud  200 . A drive cap  222  may be located around first end  186  of plunger rod  172 , and between plunger rod  172  and head  120 . When plunger  170  is an engaged state (i.e., when plunger rod  172  is in plunger opening  206 ), protrusion  220  may be located proximate and/or may abut drive cap  222 . When plunger  170  is the engaged state, rotation of first outer tube  152  about axis A-A′ causes shroud  200  to rotate in the same direction about axis A-A′ as first outer tube  152  due to the contact between notch  212  and first outer tube  152  and the contact between notch  212  and shroud  200 . The rotation of shroud  200  causes head  120  to rotate in the same direction about axis A-A′ as first outer tube  152  due to the contact between protrusion  220  and drive cap  222 . In this regard, a rotational force is transferred from shroud  200  to head  120  via contact between protrusion  220  and drive cap  222 . 
     When plunger rod  172  is radially aligned with plunger opening  206 , compression spring  180  forces first end  186  of plunger rod  172  into plunger opening  206  (i.e., plunger is forced into the engaged state). When plunger rod  172  is located in plunger opening  206 , the location of second end  190  and pin  188  generate an interference between a first lever surface  232  of plunger lever  174  and a first lever interference surface  234  of head  120 . In accordance with various embodiments, plunger torsion spring  192  is configured to bias first lever surface  232  toward first lever interference surface  234 . The interference (e.g., contact) between first lever surface  232  and first lever interference surface  234  blocks, or prevents, further rotation of plunger lever  174  in the first circumferential direction about  188  (i.e., the inference overcomes the biasing load being applied by plunger torsion spring  192 ). In the engaged state, plunger lever  174  may be located radially inward of an upper surface  236  of head  120 . In this regard, a distance plunger lever  174  and axis A-A′ may be less than a distance between upper surface  236  and axis A-A′. Upper surface  236  may be approximately perpendicular to first surface  124  and side surfaces  132  ( FIG.  5 B ). As used in the previous context only, “approximately” means±15° from perpendicular. In accordance with various embodiments, the spring constant of compression spring  180  is great enough to overcome the biasing load applied by plunger torsion spring  192 . 
     With reference to  FIG.  7 A , a cross-section view of first restraint  102 , taken along line  6 - 6  in  FIG.  5 B , is illustrated, with first restraint  102  in the raised position and plunger  170  in a disengaged state. To translate plunger  170  from the engaged state ( FIG.  6   ) to the disengaged state ( FIG.  7 A ), a load L 2  is applied in a second circumferential about pin  188  (e.g., in a direction opposite the biasing force applied by plunger torsion spring  192 ). The load L 2 , along with an interference between a first end  240  of plunger lever  174  and a second lever interference surface  242  of head  120 , force pin  188 , second end  190  of plunger rod  172 , and first lever surface  232  away from first lever interference surface  234  of head  120 . The translation of plunger rod  172  away from axis A-A′ causes first end  186  of plunger rod  172  to translate out of plunger opening  206 . The translation of plunger rod  172  away from axis A-A′ also compresses compression spring  180  between spring interference surface  182  and bushing  184 . 
     With reference to  FIG.  7 B , a cross-section view of first restraint  102 , taken along line  6 - 6  in  FIG.  5 B , is illustrated, with plunger  170  in the disengaged state and first restraint  102  beginning to translate toward the stowed position. In response to first end  186  of plunger rod  172  being located outside of plunger opening  206 , head  120  can rotate about shroud  200 . Stated differently, locating first end  186  of plunger rod  172  radially outward of outer circumferential surface  208  removes the interference between shroud  200  and plunger rod  172 , thereby allowing first end  186  of plunger rod  172  to translate circumferentially about axis A-A′ and along the outer circumferential surface  208  of shroud  200 . Shroud  200  does not rotate due to the contact between notch  212  and first outer tube  152 . With plunger  170  in the disengaged state, head  120  can be rotated in a second circumferential direction about shroud  200 , first outer tube  152 , and axis A-A′ (e.g., toward the stowed position) in response to a load L 3  greater than the biasing force of head torsion spring  160  being applied to head  120 . 
     As head  120  is rotated in the second circumferential direction, outer circumferential surface  208  blocks first end  186  of plunger rod  172  from translating radially inward (i.e., toward axis A-A′), thereby maintaining the distance between pin  188  and first lever interference surface  234  of head  120  and between second end  190  of plunger rod  172  and first lever interference surface  234 . The increased distance from first lever interference surface  234 , along with the biasing force applied by plunger torsion spring  192 , forces plunger lever  174  to rotate in the first circumferential direction about pin  188 . Plunger lever  174  may rotate until first lever surface  232  contacts head  120  (e.g., until plunger lever  174  contacts first lever interference surface  234 ). In the disengaged state, first end  240  of plunger lever  174  may be located above upper surface  236  of head  120 . Stated differently, a distance between first end  240  of plunger lever  174  and axis A-A′ may be greater than the distance between upper surface  236  of head  120  and axis A-A′, when plunger  170  is in the disengaged state. 
     With reference to  FIGS.  7 C and  7 D , as head  120  is rotated toward panel  32 , contact is generated between a vertical surface  260  of panel  32  and plunger lever  174 . Vertical surface  260  may be approximately perpendicular to upper surface  36  of panel  32  ( FIG.  5 B ). As used in the previous context only, “approximately” means±15° from perpendicular. The contact between vertical surface  260  and plunger lever  174  overcomes the biasing force applied by plunger torsion spring  192 , thereby forcing plunger lever  174  to rotate about pin  188  in the second circumferential direction about  188  (i.e., in a direction opposite the direction of the biasing load applied by plunger torsion spring  192 ). Stated differently, the contact between vertical surface  260  and plunger lever  174  translates first end  240  of plunger lever  174  toward second lever interference surface  242 , thereby decreasing the distance between first end  240  of plunger lever  174  and axis A-A′. 
     With reference to  FIG.  7 E , a cross-section view of first restraint  102 , taken along line  6 - 6  in  FIG.  5 B , is illustrated, with plunger  170  in the disengaged state and first restraint  102  in the stowed position. In response to first end  240  of plunger lever  174  translating past the edge of vertical surface  260 , plunger torsion spring  192  forces plunger lever  174  toward rotate in the first circumferential direction about pin  188 , thereby forcing first end  240  to translate past (e.g., above) upper surface  236  of head  120 . Load L 3  ( FIG.  7 D ) may be removed from, and/or no longer applied to, head  120  in response to first end  240  of plunger lever  174  translating past the edge of vertical surface  260 . In response to the load L 3  being removed from head  120 , head torsion spring  192  may bias head  120  in the first circumferential direction about axis A-A′. The biasing force of head torsion spring  160  forces first end  240  of plunger lever  274  toward a lower surface  262  of panel  32 . Lower surface  262  of panel is oriented away from upper surface  36  of panel. The contact between first end  240  of plunger lever  174  and lower surface  262  of panel  32  maintains head  120  in the stowed position. Stated differently, the interference between plunger lever  174  and lower surface  262  prevents first restraint  102  from translating to the raised position. 
     With reference to  FIGS.  8   , a cross-section view of second restraint  102   b , taken along line  6 - 6  in  FIG.  5 B , is illustrated, with the plunger in the disengaged state and prior to second restraint  102   b  being translated from the stowed state toward the raised state. second restraint  102   b  is substantially similar to first restraint  102   a , though second restraint  102   b  is actuated by second outer tube  352 . In accordance with various embodiments, to translate second restraint  102   b  from the stowed position to the raised position, plunger  170  is translated to the engaged position, thereby rotationally coupling head  120  to shroud  200  and first outer tube  152 . In this regard, second outer tube  352  is rotated about axis A-A′, thereby causing shroud  200  to rotate about axis A-A′. The rotation of shroud  200  brings protrusion  220  of shroud  200  into contact with drive cap  222 . Protrusion  220  and drive cap  222  are configured such that plunger opening  206  is radially aligned with the first end  186  of plunger rod  172  when protrusion  220  contacts drive cap  222 , however, the frictional force between lower surface  262  and plunger lever  174  be prevent plunger rod  172  from translating into plunger opening  206 . In this regard, the contact between protrusion  220  and drive cap  222  may force head  120  to rotate in the second circumferential direction about axis A-A′ (i.e., away from the raised position and in the direction opposite the direction of the biasing load applied by head torsion spring  160 ). The rotation of head  120  in the second circumferential direction about axis A-A′ forces first end  240  of plunger lever  174  away from lower surface  262  of panel  32 . 
     With additional reference to  FIG.  12   , inner shaft  154  drives rotation of second outer tube  352 . In that regard, inner shaft actuator assembly  976  may be used to rotate inner shaft  154  to cause actuation of second restrain  102   b.    
     With reference to  FIG.  9   , coaxial actuator assembly  110  is illustrated, in accordance with various embodiments is illustrated. Coaxial actuator assembly  110  may couple with drive shaft assembly  150 , wherein the first outer tube  152  and the inner shaft  154  are disposed coaxially about the A-A′ axis. Coaxial actuator assembly  110  comprises inner shaft actuator assembly  976  and first outer tube actuator assembly  975 . First outer tube actuator assembly  975  includes a first spring loaded plunger lever  906 . Additionally, coaxial actuator assembly  110  includes inner shaft actuator assembly  976  coupled to the drive shaft assembly  150 . Second spring loaded plunger lever  908  may be coupled to the inner shaft actuator assembly  976 . 
     First outer tube actuator assembly  975  further includes a first geometric gripping surface  910 . Inner shaft actuator assembly  976  includes a second geometric gripping surface  912 . A tool may be used to grip on and rotate the first geometric gripping surface  910  or the second geometric gripping surface  912 . The tool may be a wrench, channel lock pliers, pliers or any other suitable tool which can grip on to a geometric surface and impart rotation around the axis. The tool may also be a motorized system, such as an electromechanical actuator and/or electric motor such as a brushless DC motor, which may receive a command to rotate the first geometric gripping surface  910  or second geometric gripping surface  912  in response to a rotational command by a controller. The rotational command may be transmitted by the controller to the motorized system in response to a switch being activated. 
     With reference to  FIG.  9    and  FIG.  10   , a cross-section view of first outer tube actuator assembly  975  of the coaxial actuator assembly  110  in  FIG.  9    is illustrated. The first outer tube actuator assembly  975  may comprise a first actuator tube  914  disposed within the first outer tube actuator assembly  975 . The first actuator tube  914  is coupled to the first outer tube  152  at a first notch  916  and a second notch  918 . The first notch  916  and the second notch  918  may be extensions of the first outer tube  152  which are configured to rotate the first outer tube  152  in response to rotation of the first actuator tube  914 . The first notch  916  and the second notch  918  may be disposed on opposite sides of the first outer tube  152 . Rotation of the first actuator tube  914  about axis A-A′ causes first outer tube  152  to rotate in the same direction about axis A-A′ as first actuator tube  914  due to the contact between first notch  916  and first actuator tube  914  and the contact between second notch  918  and first actuator tube  914 . 
     A first spring loaded plunger  924  is disposed within the first outer tube actuator assembly  975 , and the first spring loaded plunger  924  includes a first spring loaded plunger rod  926  and the first spring loaded plunger lever  906 . First spring loaded plunger rod  926  is configured to translate radially (i.e., perpendicular to axis A-A′). In this regard, first spring loaded plunger rod  926  translates toward and away from first outer tube  152 . In various embodiments, first spring loaded plunger rod  926  may be located in a first spring loaded plunger channel  928 . A compression spring  930  may be located about first spring loaded plunger rod  926 . Compression spring  930  may be compressed between a first spring interference surface  932  and a second spring interference  934  formed by the first spring loaded plunger rod  926 . Compression spring  930  biases a first end of plunger rod in the radially inward direction (i.e., toward first outer tube  152  and axis A-A). Compression spring  930  comprises any suitable spring, such as a coil spring, leaf spring, Belleville spring, or the like 
     A first actuator lever pin  936  may be located through first spring loaded plunger rod  926  and first spring loaded plunger lever  906 . First actuator lever pin  936  may be located proximate a second end of first spring loaded plunger rod  926 . The second end of first spring loaded plunger rod  926  is opposite the first end. First spring loaded plunger lever  906  may rotate about first actuator lever pin  936 . A first plunger torsion spring may be located about first actuator lever pin  936  and may apply a biasing load to first spring loaded plunger lever  906 . First plunger torsion spring may bias first spring loaded plunger lever  906  in the first circumferential direction about first actuator lever pin  936 . 
     The first actuator tube  914  also comprises a first actuator tube opening  920  and a second actuator tube opening  922 . The first spring loaded plunger  924  is configured to fit into the first actuator tube opening  920  and the second actuator tube opening  922 . When the first spring loaded plunger  924  is in the first actuator tube opening  920  or the second actuator tube opening  922 , then the first actuator tube  914  and the first outer tube  152  are prevented from rotating about the A-A′ axis. In response to a force exerted on the first spring loaded plunger lever  906  in the direction towards the drive shaft assembly  150 , the first spring loaded plunger rod  926  translates in the direction opposite the first outer tube  152  and perpendicular to the A-A′ axis. This allows both the first actuator tube  914  and the first outer tube  152  to rotate about the A-A′ axis. The first outer tube  152  and the first actuator tube  914  coaxially rotate about the A-A′ axis in response to the first spring loaded plunger lever  906  translating the first spring loaded plunger  924  out of the first actuator tube opening  920  or the second actuator tube opening  922 , and in response to the first geometric gripping surface  910  driving rotation of the first outer tube  152 . 
     With reference to  FIG.  9    and  FIG.  11   , a cross-section view of the comprises inner shaft actuator assembly  976  of the coaxial actuator assembly  110  in  FIG.  9    is illustrated. The inner shaft actuator assembly  976  comprises a second actuator tube  938 . Second actuator tube  938  is coupled to the inner shaft  154  at a first notch  940  and a second notch  942 . The first notch  940  and the second notch  942  may be extensions of the inner shaft  154  which are configured to rotate the inner shaft  154  in response to rotation of the second actuator tube  938 . The first notch  940  and the second notch  942  may be disposed on opposite sides of the inner shaft  154 . Rotation of the second actuator tube  938  about axis A-A′ causes inner shaft  154  to rotate in the same direction about axis A-A′ second actuator tube  938  due to the contact between first notch  940  and second actuator tube  938  and the contact between second notch  942  and second actuator tube  938 . 
     A first spring loaded plunger  944  is disposed within inner shaft actuator assembly  976 , and the first spring loaded plunger  944  includes a second spring loaded plunger rod  946  and the second spring loaded plunger lever  908 . Second spring loaded plunger rod  946  is configured to translate radially (i.e., perpendicular to axis A-A′). In this regard, second spring loaded plunger rod  946  translates toward and away from inner shaft  154 . In various embodiments, second spring loaded plunger rod  946  may be located in a second spring loaded plunger channel  948 . Compression spring  950  may be located about second spring loaded plunger rod  946 . Compression spring  950  may be compressed between first spring interference surface  952  and a second spring interference  954  formed by the second spring loaded plunger rod  946 . Compression spring  950  biases a first end of second spring loaded plunger rod  946  in the radially inward direction (i.e., toward inner shaft  154  and axis A-A). Compression spring  950  comprises any suitable spring, such as a coil spring, leaf spring, Belleville spring, or the like 
     A first actuator lever pin  956  may be located through second spring loaded plunger rod  946  and second spring loaded plunger lever  908 . First actuator lever pin  956  may be located proximate a second end of second spring loaded plunger rod  946 . The second end of second spring loaded plunger rod  946  is opposite the first end. Second spring loaded plunger lever  908  may rotate about first actuator lever pin  956 . A first plunger torsion spring may be located about first actuator lever pin  956  and may apply a biasing load to second spring loaded plunger lever  908 . First plunger torsion spring may bias first spring loaded plunger lever  906  second spring loaded plunger lever  908  in the first circumferential direction about first actuator lever pin  956 . 
     Second actuator tube  938  also comprises a first actuator tube opening  957  and a second actuator tube opening  958 . The spring loaded plunger  944  is configured to fit into the first actuator tube opening  957  and the second actuator tube opening  958 . When the spring loaded plunger  944  is in the first actuator tube opening  957  or the second actuator tube opening  958 , then the second actuator tube  938  and the inner shaft  154  are prevented from rotating about the A-A′ axis. In response to a force exerted in the direction towards the drive shaft assembly  150  to the second spring loaded plunger lever  908 , then the second spring loaded plunger rod  946  translates in the direction opposite the inner shaft  154  and perpendicular to the A-A′ axis and allows both the first actuator tube  914  and the first outer tube  152  to rotate about the A-A′ axis. The inner shaft  154  and the second actuator tube  938  rotate about the A-A′ axis in response to the second spring loaded plunger lever  908  translating the second spring loaded plunger rod  946  out the first actuator tube opening  957  or the second actuator tube opening  958 , and in response to the second geometric gripping surface  912  driving rotation of the inner shaft  154 . 
     Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials. 
     Systems, methods, and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is intended to invoke 35 U.S.C. 112(f), unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.