Patent Publication Number: US-11660760-B2

Title: Low-profile manipulator interface system

Description:
FIELD 
     The present disclosure relates to a low mass system for releasably securing one end of a robotic arm (or any other selected object) to a purpose-built attach point on a spacecraft, permitting the robotic arm (or selected object) to be moved from one purpose-built attach point location on the spacecraft and to allow the free end of the robotic arm (selected object) to be secured to any payload also similarly equipped such that this payload may be manipulated by the robotic arm or connected to the selected object. 
     BACKGROUND 
     The use of robotics within the context of space operations is well known. Also well known is that one of the overriding constraints of space operations is low mass to reduce the costs to launch objects into space. Efforts to introduce commonality into space system interfaces enhance interoperability and also reduce overall spacecraft mass and complexity, thus reducing the costs to develop and operate these space systems in both the short and long term. 
     The benefit of any robotic system is greatly enhanced if its mounting point or base can be moved from place to place so that it may act wherever needed with as few limitations as possible. A robotic system or arm that can move itself from location to location within its environment creates a further benefit. This benefit has been realized before in systems such as the Space Station Remote Manipulator System (SSRMS) currently operating on the International Space Station (ISS). The SSRMS&#39; purpose-built attach points are Power Data Grapple Fixtures (PDGF&#39;s) which are located at various locations around the ISS, providing a mechanical attach point, as well as power, data and video connections to the manipulator via its Latching End Effectors (LEE) which are located at either end of the seven (7) jointed SSRMS. 
     One of the special conditions of activities in space is the microgravity environment. Of special interest with respect to robotic arms is that within a microgravity environment a robotic arm need no longer account for the effects of Earth gravity which can result in the two ends of a robotic arm being designed with identical structural capacities without excessive mass penalties. This would not be the case under Earth gravity where the base of an arm, analogous to a human shoulder, must be significantly stronger, and therefore heavier, than the wrist or hand of an arm. The ability to make the two ends of an arm similar in terms of structural capability permits the concept of an arm that may self-move, end over end-wise, or “walk”, from one prepared location to another on the spacecraft. In such a case, because of the number of these prepared locations, reducing their mass and complexity reaps significant benefits to the entire spacecraft system. 
     In addition, the benefits of any robotic system can be enhanced by increasing the number of objects the robotic system can interface with or grasp and subsequently manoeuvre. This can be achieved, to a degree, by creating an interface system where that portion of the interface that is to be replicated most often is also of the lowest possible mass and of the least size and complexity, thereby reducing the overall mass and cost burden on the complement of objects to be handled by the robotic system and encouraging more objects to be compatible with the robotic system. 
     If the interface at the base of a robotic arm can be the same as the interface between the robotic arm and any object being handled or acquired and then manoeuvred, the benefits are multiplied yet again. 
     The Low-Profile Manipulator Interface System disclosed herein consists of two primary subassemblies; a relatively complex and heavier “active”, subassembly that is permanently attached to both ends of the robotic system or arm, and a low-mass, simple, “passive” subassembly that is attached to objects the robotic system will be based upon or to objects will manipulate. This passive subassembly is both capable of providing the full structural and electrical support needed to act as the base that enables the robotic arm&#39;s complete range of capability and of sufficiently low cost and mass to be added to any payloads that require robotic manipulation. 
     In order to control such complex electromechanical systems effectively, sensors can be used to create an artificial sense of touch or feel allowing the control system to precisely align and control movements of the end of the manipulator when in contact with other components, such as the passive portion of the interface, substantially easing such activities. To date, one problem that has at times limited these grasping operations of the attach point is that this force-moment sensing apparatus has been part of the primary manipulator load path and has had to possess a sufficient dynamic force sensing range to measure both the very small forces generated when attempting to delicately mate an arm to a payload and the much larger forces generated while moving these payloads, or the entire manipulator, from place to place. 
     SUMMARY 
     Disclosed herein is low mass system for releasably securing one end of a robotic manipulator (or robotic arm, or any other selected object) to a purpose-built attach point on a spacecraft, permitting the robotic arm to be move from one purpose-built attach point location on the spacecraft and to allow the free end of the robotic arm to be secured to any payload also similarly equipped such that this payload may be manipulated by the robotic arm. 
     This system and mechanism that releasably and structurally permits a robotic arm to be mounted to a spacecraft or attach a payload to the free end of the manipulator facilitates both the movement of the robotic arm from one place to another via a network of passive interface locations on the spacecraft and provides for the low cost and low mass releasable attachment of various payloads to the robotic arm while separating the force-moment sensing during the mating/demating of the interface from that required to manipulate payloads once the interface has been mounted to the payload or spacecraft. 
     An embodiment disclosed herein provides a mechanism for releasably mounting a robotic arm to a spacecraft and to payloads that the arm might acquire, manoeuvre and insert or remove from mounting locations on the spacecraft. The method of mounting the arm to the spacecraft is especially designed to permit the arm to be moved, under its own power, from mounting point to mounting point around the spacecraft in order to provide robotic services at various locations around the spacecraft. To that end, all of the active or driven components of the system are contained within that portion of the system that is permanently attached to the robotic arm, termed the “active interface assembly”. The portions of the system attached to the host spacecraft or any payloads contain no mechanisms that are independently driven, and are termed the “passive interface assembly” and need not contain any electrical connections unless used as a mounting base for the arm or unless the payload itself requires power and/or data connections to keep it heated or to provide data via the arm to the other computer systems on the spacecraft. 
     The active portion of the interface contains the latching mechanisms that hold the active and passive portions of the interface together thus providing the structural load carrying capacity necessary for the robotic arm to perform useful tasks. In one embodiment, it also contains force and/or moment sensors mounted on alignment features on the passive interface that are by the control system of the manipulator to align the mating interfaces during the mating process. These sensors are so located that they are not in the structural load path of the robotic system once mated. By positioning these sensors in such a way, the dynamic range of the sensor can be reduced, easing the manufacture and test of such sensors and increasing reliability and robustness by eliminating several sources of potential errors in the control system which is limiting and controlling the forces and moments which occur during the mating process. 
     An embodiment of the interface coupling system for releasably securing a selected object to a spacecraft and securing various payloads to the selected object and to each other comprises 
     a) an active interface assembly including
         a first coupling located at its proximal end for structurally attaching it to the selected object,   electrical connections for electrically connecting it to said selected object,   a second coupling located at its distal end,   an active interface assembly latch mechanism;   an active interface assembly alignment mechanism;   a computer control system connected to said active interface assembly latch mechanism;       

     b) a passive interface assembly including
         a first coupling located at its proximal end complementary to said second coupling on the active interface assembly for structurally attaching said passive interface assembly to said second coupling,   a second coupling located at its distal end for affixing said passive interface assembly to a desired object,   a passive interface assembly alignment mechanism complementary to said active interface assembly alignment mechanism;   passive latch features complementary to, and engageable with, said active interface assembly latch mechanism; and       

     c) a sensor mechanism mounted and configured for sensing the forces and moments that occur during a sequence of aligning the active and passive interface assemblies together, said sensor mechanism being connected to said computer control system; and 
     d) said computer control system being programmed with instructions to use the sensed forces and moments output from said sensor mechanism to control the alignment of said active and passive interface assemblies until they are sufficiently aligned to initiate a latching sequence to releasably and rigidly lock said active and passive interface assemblies together. 
     The sensor mechanism may be mounted in the active interface assembly, and wherein the sensor mechanism does not run through a primary structural load path of the passive and active interfaces or selected object. 
     The sensing mechanism may be a force moment sensor operably coupled to the active interface assembly alignment mechanism and configured to sense forces and moments on the active interface assembly alignment mechanism during alignment and engagement of the active interface assembly alignment mechanism to the passive interface assembly alignment mechanism. 
     The sensor mechanism may be mounted in said passive interface assembly, and wherein said passive interface assembly includes electrical connections configured to connect said sensor mechanism to said computer control system. 
     The sensor mechanism may be mounted in the selected object. 
     The selected object may be a robotic manipulator. 
     The interface coupling system may further comprise a sensor system mounted on one or both of the active and passive interface assemblies for enabling remote operator control of all activities associated with aligning and latching the active and passive interface assemblies together based on feedback from the sensor system. 
     The sensor system may comprise any one or combination of a camera based vision system, radar and LIDAR. 
     The second coupling on the active interface assembly and the first coupling on the passive interface assembly may be matched halves of a Hirth coupling. 
     The passive interface assembly mechanism may include one or more elongate alignment pins, and the active interface assembly alignment mechanism may comprise one or more elongate alignment sockets having a size and shape to accept the one or more elongate alignment pins. 
     The latch mechanism may include an actuator connected to the computer control system and latch arms wherein once the active and passive interface assemblies have come into sufficient contact, based on feedback from the sensor mechanism, the computer control system instructs the actuator to advance thereby forcing the latches outwards and into engagement with said passive latch features within the passive interface assembly to lock the active and passive interface assemblies together. 
     A further understanding of the functional and advantageous aspects of the disclosure can be realized by reference to the following detailed description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the mechanism for releasably securing a robotic system or arm to a spacecraft or payload will now be described, by way of example only, with reference to the drawings, in which: 
         FIG.  1    shows an overall view of the entire system showing how the various principle elements relate to each other. 
         FIG.  2    is an overall isometric view of the active and passive parts of the interface system looking towards the Passive Interface Assembly (PIA). 
         FIG.  3    is an overall isometric view of the active and passive parts of the interface system looking towards the Active Interface Assembly (AIA). 
         FIG.  4    is an end view of the AIA showing the various section planes used in other figures. 
         FIG.  5    is an end view of the PIA showing the various section planes used in other figures. 
         FIG.  6    is an isometric view of the AIA identifying the main externally visible features. 
         FIG.  7    is an isometric sectional view of the AIA taken along line A-A of  FIG.  4   . 
         FIG.  8    is a sectional view of the AIA taken along line A-A of  FIG.  4   . 
         FIG.  9    is an isometric sectional view of the AIA taken along line B-B of  FIG.  4   . 
         FIG.  10    is a sectional view of the AIA taken along line B-B of  FIG.  4   . 
         FIG.  11    is an isometric sectional view of the AIA taken along line C-C of  FIG.  4   . 
         FIG.  12    is a sectional view of the AIA taken along line C-C of  FIG.  4   . 
         FIG.  13    is an isometric sectional view of the AIA taken along line D-D of  FIG.  4   . 
         FIG.  14    is a sectional view of the AIA taken along line D-D of  FIG.  4   . 
         FIG.  15    is an interior end view of the AIA showing the general arrangement of the actuator and gear train. 
         FIG.  16    is a repeat  FIG.  14    with the gear train housing and rear housing removed for clarity showing the arrangement of the gear train. 
         FIG.  17    is a repeat of  FIG.  16    except at as an isometric view. 
         FIG.  18    is an isometric view of the PIA identifying the main features. 
         FIG.  19    is an isometric sectional view of the PIA taken along line E-E of  FIG.  4   . 
         FIG.  20    is a sectional view of the PIA taken along line E-E of  FIG.  4   . 
         FIG.  21    is an isometric sectional view of the PIA taken along line F-F of  FIG.  4   . 
         FIG.  22    is a sectional view of the PIA taken along line F-F of  FIG.  4   . 
         FIG.  23 A to  23 E  shows series of figures illustrating the alignment and contact of the AIA onto the PIA in which: 
         FIG.  23 A  shows the approach; 
         FIG.  23 B  shows contact (at the maximum lateral offset of the active half of the AIA with respect to the PIA); 
         FIG.  23 C  shows lateral alignment and advance of the AIA with respect to the PIA; 
         FIG.  23 D  shows full coarse alignment of the AIA to the PIA; and 
         FIG.  23 E  shows the AIA nearly in full alignment and contact with the PIA. 
         FIG.  24 A to  24 E  show a series of Figures illustrating the operation of the AIA latching mechanism as it achieves the structural and electrical connection between the AIA and the PIA in which: 
         FIG.  24 A  shows the latch sequence at approximately the same point in the sequence as illustrated in  FIG.  23 E , with coarse alignment achieved and coupling halves in light contact; 
         FIG.  24 B  shows the actuator advancing and forcing the latches outwards, 
         FIG.  24 C  shows the latches further deployed to the point where the AIA may no longer completely separate from the PIA; 
         FIG.  24 D  shows the latches fully engages with the ramps on the PIA, ensuring the AIA is fully structurally mated to the PIA but the electrical connection has yet to be completed; and 
         FIG.  24 E  shows the latch mechanism with the actuator fully extended, the latches fully engaged on the ramps and the electrical connectors fully mated. 
         FIG.  25    is a system block diagram illustrating the principle functional blocks and connections when the manipulator is mated to the spacecraft but has not yet mated to a payload. 
         FIG.  26    is a system block diagram which like  FIG.  25    shows the mating interface between the arm and spacecraft but also shows the connections between the other end of the robotic arm which is terminated with a second AIA that mates to the PIA on a payload. 
         FIG.  27    is a system block diagram illustrating the principle functional blocks and connections when the manipulator is mated to the spacecraft at two locations, an essential state in the process of “walking” the manipulator from one PIA to another on the same spacecraft. 
         FIG.  28 A to  28 C  show a series of Figures illustrating an alternate embodiment showing how a payload  130  may be releasably berthed to a spacecraft  120  via the use of an AIA  400  fixed to the spacecraft  120  and a PIA  200  fixed to a payload  130 . 
         FIG.  28 A  shows the manipulator  100  manoeuvering attached payload  130  fitted with a PIA  200  towards an AIA  400  fixed to the spacecraft  120 . 
         FIG.  28 B  shows the payload  130  releasably mated to both the manipulator  100  and the spacecraft  120 . 
         FIG.  28 C  shows the payload  130  now releasably mated to the spacecraft  120  with the manipulator  100  free to perform other tasks. 
         FIG.  29 A to  29 D  are a series of Figures illustrating an alternate embodiment showing a series of payloads  130  releasably mated to each other using a plurality of AIAs  400  and PIAs  200  fixed to each payload  130  and to a spacecraft  120 . 
         FIG.  29 A  shows the PIA  200  on a first payload  130  being moved towards an AIA  400  about to be berthed to the spacecraft  120 . 
         FIG.  29 B  shows a payload  130  now releasably mated to the spacecraft  120  and an additional payload  130  being manoeuvered in anticipation of being mated the payload  130  currently releasably mated to the spacecraft  130 . 
         FIG.  29 C  shows an additional payload  130  having been mated to the previous two creating a larger assemblage, 
         FIG.  29 D  shows the larger assemblage of payloads  130  with the manipulator  100  attached to a PIA  200  on the assemblage, and having been released by the spacecraft-mounted AIA  400 , being moved away from the spacecraft  130 . 
         FIG.  30    is a repeat of  FIG.  2    with the addition of a camera system mounted to the AIA  400  that via viewing angle  170  can see a target  180  located in a known position relative to the PIA  200 . 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments and aspects of the disclosure will be described with reference to details discussed below. The following description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. The drawings are not necessarily to scale. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure. 
     As used herein, the terms, “comprises” and “comprising” are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in this specification including claims, the terms, “comprises” and “comprising” and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components. 
     As used herein, the term “exemplary” means “serving as an example, instance, or illustration,” and should not be construed as preferred or advantageous over other configurations disclosed herein. 
     As used herein, the terms “about” and “approximately”, when used in conjunction with ranges of dimensions of particles, compositions of mixtures or other physical properties or characteristics, are meant to cover slight variations that may exist in the upper and lower limits of the ranges of dimensions so as to not exclude embodiments where on average most of the dimensions are satisfied but where statistically dimensions may exist outside this region. It is not the intention to exclude embodiments such as these from the present disclosure. 
     The following is a description of the preferred embodiment of the low-profile manipulator interface system. Additional embodiments will also be described. 
     The preferred embodiment consists of the following components in reference to the Figures. 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 100 
                 Manipulator 
               
               
                   
                 110 
                 Arm Subassembly 
               
               
                   
                 120 
                 Spacecraft 
               
               
                   
                 130 
                 Payload 
               
               
                   
                 140 
                 Ground Station 
               
               
                   
                 150 
                 Radio Communications 
               
               
                   
                 160 
                 Camera system 
               
               
                   
                 170 
                 Field of View 
               
               
                   
                 180 
                 Target 
               
               
                   
                 200 
                 Passive Interface Ass&#39;y 
               
               
                   
                 210 
                 1 st  half of Hirth Coupling 
               
               
                   
                 220 
                 Connector Frame 
               
               
                   
                 230 
                 Latch Ramp 
               
               
                   
                 240 
                 Alignment Pin 
               
               
                   
                 250 
                 Passive Housing 
               
               
                   
                 260 
                 Ramp Doubler 
               
               
                   
                 270 
                 Housing Fastener 
               
               
                   
                 280 
                 Connector 
               
               
                   
                 290 
                 Connector Bracket 
               
               
                   
                 300 
                 Computer Control System 
               
               
                   
                 350 
                 Latch Cam Surface 
               
               
                   
                 400 
                 Active Interface Assembly 
               
               
                   
                 410 
                 Forward Housing 
               
               
                   
                 420 
                 Aft Housing 
               
               
                   
                 430 
                 2 nd  half of Hirth Coupling 
               
               
                   
                 440 
                 Microswitch 
               
               
                   
                 450 
                 Pillar Support 
               
               
                   
                 460 
                 Tapered Gib 
               
               
                   
                 470 
                 Linear Bearing Rail 
               
               
                   
                 480 
                 Linear Bearing Platform 
               
               
                   
                 500 
                 Latch Assembly 
               
               
                   
                 510 
                 Latch Arm 
               
               
                   
                 520 
                 Latch Roller 
               
               
                   
                 530 
                 Roller bushing 
               
               
                   
                 540 
                 Midplane Plate 
               
               
                   
                 550 
                 Latch Pillar 
               
               
                   
                 560 
                 Pillar Bushing 
               
               
                   
                 570 
                 Load Sensor Washer 
               
               
                   
                 580 
                 Load Sensor 
               
               
                   
                 590 
                 Spring Washer 
               
               
                   
                 600 
                 Bellville Springs 
               
               
                   
                 610 
                 Spring Housing 
               
               
                   
                 620 
                 Jam Nut 
               
               
                   
                 630 
                 Connector Plate 
               
               
                   
                 640 
                 Actuator Roller 
               
               
                   
                 650 
                 Connector 
               
               
                   
                 660 
                 Actuator Frame 
               
               
                   
                 670 
                 Cable Guide 
               
               
                   
                 680 
                 Ball Screw 
               
               
                   
                 690 
                 Latch Bearing 
               
               
                   
                 700 
                 Keyed bushing 
               
               
                   
                 710 
                 Actuator Needle Bearing 
               
               
                   
                 720 
                 Latch Needle Bearing 
               
               
                   
                 730 
                 Latch Axle 
               
               
                   
                 740 
                 Actuator Axle 
               
               
                   
                 750 
                 Pillar Axle 
               
               
                   
                 760 
                 Microswitch 
               
               
                   
                 770 
                 Microswitch Tree 
               
               
                   
                 780 
                 Bushing 
               
               
                   
                 790 
                 Microswitch Actuation Surface  
               
               
                   
                 800 
                 Alignment Socket 
               
               
                   
                 810 
                 Force Moment Sensor (FMS) 
               
               
                   
                 820 
                 FMS Plate 
               
               
                   
                 830 
                 Spring Bushing 
               
               
                   
                 840 
                 Reaction Washer 
               
               
                   
                 850 
                 Spring 
               
               
                   
                 860 
                 Stiffener Plate 
               
               
                   
                 900 
                 Geartrain Housing 
               
               
                   
                 910 
                 Motor 
               
               
                   
                 920 
                 Idler Gear 
               
               
                   
                 930 
                 Latch Drive Gear 
               
               
                   
                 940 
                 Motor Output Gear 
               
               
                   
                 950 
                 Motor Bearing 
               
               
                   
                 960 
                 Motor Mount Plate 
               
               
                   
                 970 
                 Motor Bearing plate 
               
               
                   
                 980 
                 Idler Bearing Plate 
               
               
                   
                 990 
                 Idler Bearing 
               
               
                   
                   
               
            
           
         
       
     
     In an embodiment there is provided an interface coupling system for releasably securing a selected object to a spacecraft and securing various payloads to the selected object and to each other. The coupling system is comprised of an active interface assembly including 1) a first coupling located at its proximal end for structurally attaching it to the selected object, 2) electrical connections for electrically connecting it to the selected object, 3) a second coupling located at its distal end, 4) an active interface assembly latch mechanism, 5) an active interface assembly alignment mechanism, and 6) a computer control system connected to the active interface assembly latch mechanism. This embodiment also includes a passive interface assembly including 1) a first coupling located at its proximal end complementary to the second coupling on the active interface assembly for structurally attaching the passive interface assembly to said second coupling, 2) a second coupling located at its distal end for affixing the passive interface assembly to a desired object, 3) a passive interface assembly alignment mechanism complementary to said active interface assembly alignment mechanism, 4) a passive latch features complementary to, and engageable with, the active interface assembly latch mechanism. This embodiment further includes a sensor mechanism mounted and configured for sensing the forces and moments that occur during a sequence of aligning the active and passive interface assemblies together and the sensor mechanism is connected to the computer control system. The computer control system being programmed with instructions to use the sensed forces and moments output from the sensor mechanism to control the alignment of the active and passive interface assemblies until they are sufficiently aligned to initiate a latching sequence to releasably and rigidly lock the active and passive interface assemblies together. 
     In an embodiment the sensor mechanism is mounted in the active interface assembly, and wherein the sensor mechanism does not run through a primary structural load path of the passive and active interfaces or selected object. In this embodiment the sensing mechanism is a force moment sensor operably coupled to the active interface assembly alignment mechanism and configured to sense forces and moments on the active interface assembly alignment mechanism during alignment and engagement of the active interface assembly alignment mechanism to the passive interface assembly alignment mechanism. 
     In an embodiment the sensor mechanism is mounted in the passive interface assembly, and the passive interface assembly includes electrical connections configured to connect the sensor mechanism to the computer control system. 
     In an embodiment the sensor mechanism is mounted in the selected object. 
     In the above mentioned embodiments the selected object is a robotic manipulator. 
     In the above mentioned embodiments further comprising a sensor system mounted on one or both of the active and passive interface assemblies for enabling remote operator control of all activities associated with aligning and latching the active and passive interface assemblies together based on feedback from the sensor system. This sensor system comprises any one or combination of a camera based vision system, radar and LIDAR. 
     In all the embodiments mentioned above the second coupling on the active interface assembly and the first coupling on the passive interface assembly are matched halves of a Hirth coupling. 
     In all the embodiments mentioned above the passive interface assembly mechanism includes one or more elongate alignment pins, and the active interface assembly alignment mechanism comprises one or more elongate alignment sockets having a size and shape to accept the one or more elongate alignment pins. 
     In all the embodiments mentioned above the latch mechanism includes an actuator connected to the computer control system and latch arms wherein once the active and passive interface assemblies have come into sufficient contact, based on feedback from the sensor mechanism, said computer control system instructs the actuator to advance thereby forcing the latches outwards and into engagement with the passive latch features within the passive interface assembly to lock the active and passive interface assemblies together. 
     Further structural and operational details of the interface coupling system will be described in detail with respect to the Figures hereinafter. 
     As shown in  FIG.  1   , the Low-Profile Manipulator Interface System consists of two primary components, the passive interface assembly PIA  200  and the active interface assembly AIA  400 . The AIA  400  is attached to an arm subassembly  110  forming part of manipulator  100  with numerous degrees of motional freedom sufficient to perform its design tasks. As illustrated in  FIG.  1   , the arm subassembly  110  has seven degrees of freedom, but this is not a requirement. In terms of this disclosure, the arm subassembly  110  shown acts to manoeuver the AIA  400  into proximity of the PIA  200  and then to accomplish, in the manner described below, the coarse positioning of the AIA  400  relative to the PIA  200  such that a final structural and electrical mating of the two subassemblies may be accomplished by mechanisms within the AIA  400 . In this embodiment, the PIA  200  is attached to the host spacecraft  120  and to the payload  130  using housing fasteners  270  ( FIG.  3   ). A payload  130  or a spacecraft  120  may have numerous PIA  200  subassemblies attached to it as required by mission parameters. Each PIA  200  may serve as a structural connection and, if sufficient electrical connection capability is installed, as an electrical connection to the arm subassembly  110 . 
       FIG.  2    shows the principle components of the low-profile manipulator interface system when viewed from the outside while looking towards the PIA  200 . The PIA  200  consists of first half of the Hirth coupling pair  210 , connector frame  220 , latch ramp  230 , alignment pins  240 , passive housing  250 , ramp doubler  260 , housing fasteners  270 , connectors  280 , and connector bracket  290 . 
     On the AIA  400  can be seen the forward housing  410 , aft housing  420 , the second half of the Hirth coupling pair  430 , microswitch  440 , midplane plate  540 , latch pillar  550 , load sensor  580 , spring housing  610 , jam nuts  620 , alignment socket  800 , geartrain housing  900 , motor  910 , and motor mount plate  960 . 
       FIG.  3    is similar to  FIG.  2    except looking in the opposite direction down the long axis. On the PIA  200  is shown Hirth coupling  210 , passive housing  250 , ramp doubler  260  and the housing fasteners  270 . 
     On the AIA  400  it shows the forward housing  410 , aft housing  420 , Hirth coupling  430 , midplane plate  540  (see  FIG.  2   ), latch assemblies  500 , and the alignment sockets  800 . 
       FIG.  4    is an end view of the AIA  400  showing the locations of the four section lines, A-A, B-B, C-C and D-D used in other Figures as described below. 
       FIG.  5    is an end view of the PIA  200  showing the locations of the two section lines, E-E and F-F used in other Figures as described below. 
       FIG.  6    is an exterior isometric view of the AIA  400  showing the forward housing  410 , aft housing  420 , Hirth coupling  430 , microswitch  440 , midplane plate  540 , latch assembly  500 , and the alignment sockets  800 . 
       FIG.  7    is an isometric section view through section line A-A of  FIG.  4    which runs through the centreline of one of the at least one latch assemblies  500 . The latch rollers  520  rotate on the roller bushings  530  around the latch axle  730 . The latch axles  730  are located in each of the two latch arms  510  that rotate about the pillar axles  750  secured to the two latch pillars  550  that are part of each latch assembly  500 . 
     The latch pillars  550  are secured to the midplane plate  540  such that they may translate longitudinally via the pillar bushings  560  but are secured against motion in other axes. Longitudinal latch pillar  550  motion is resisted by a series of Belleville springs  600  that are contained in a spring housing  610  and retained on the shaft of the latch pillar  550  by two jam nuts  620  that may be adjusted in position to provide an initial preload in the Belleville springs  600  that ensures the latch assembly  500  does not excessively move during operation or launch from Earth. The Belleville springs  600  contact the spring washer  590  which translates the ring contact of the Belleville springs  600  to a more even surface contact force on the face of the load sensor  580  which then bears on the midplane plate  540  via a load sensor washer  570 . 
     The midplane plate  540  is sandwiched between the rear housing  420  and the forward housing  410  to which the 2 nd  half of the Hirth coupling  430  is attached. Affixed to the forward housing  410  are the pillar supports  450  which restrict the outward bending of the latch pillar  550  under interface rigidization loads. 
     Actuating the latching mechanism are the drive train components. The motion of the latch arms  510  is driven by actuator rollers  640  being moved longitudinally along the latch cam surfaces  350  on the latch arms  510 . The latch cam surfaces  350  (see  FIG.  8   ) act as cams and the actuator rollers  640  act as cam followers. The connector plate  630  serves to support the actuator rollers  640  and hold one half of an electrical connector pair  650 . The actuator rollers  640  rotate against actuator needle bearings  710 . The connector plate  630  is connected, via the actuator frame  660  and the keyed bushing  700  to the shaft of the ball screw  680 . The bearing portion of the ball screw  680  is connected to the latch drive gear  930  which is supported by two latch bearings  690 , one in the midplane plate  540  and the second in the geartrain housing  900 . 
     The actuator frame  660  is attached to the linear bearing platform  480  (see  FIG.  8   ) which, running along the linear bearing rail  470 , guides and structurally supports the motion of the actuator frame  660  during mechanism operation. The linear bearing rail  470  is accurately positioned within the forward housing  410  by the use of a tapered gib  460 . 
     Cable guides  670  are affixed to the actuator frame  660  and translate with the actuator components. The cable guides  670  provide a method for protecting and guiding wires that come from the arm subassembly  110  and connect to the electrical connector  650  ensuring they do not snag on other items within the mechanism. Cables or wires are not shown in the figures for clarity. 
       FIG.  8    is a true section view through section line A-A of  FIG.  4   . It shows latch rollers  520 , roller bushings  530 , latch axles  730 , latch arms  510 , pillar axles  750 , latch pillars  550 , midplane plate  540 , latch cam surfaces  350 , pillar bushings  560 , Belleville springs  600 , spring housing  610 , jam nuts  620 , spring washer  590 , load sensor  580 , load sensor washer  570 , rear housing  420 , forward housing  410 , Hirth coupling  430 , pillar supports  450 , connector plate  630 , actuator rollers  640 , connector  650 , actuator frame  660 , keyed bushing  700 , ball screw  680 , latch drive gear  930 , latch bearings  690 , tapered gib  460 , linear bearing rail  470 , linear bearing platform  480 , and cable guides  670 . 
       FIG.  9    is an isometric section view through section line B-B of  FIG.  4    showing the entirety of one of the at least one latch assemblies  500  ( FIGS.  3 ,  6   ). It shows latch rollers  520 , latch needle bearings  720 , latch axles  730 , latch arms  510 , pillar axles  750 , latch pillars  550 , midplane plate  540 , spring housing  610 , jam nuts  620 , rear housing  420 , forward housing  410 , Hirth coupling  430 , pillar supports  450 , connector plate  630 , actuator rollers  640 , actuator needle bearing  710 , electrical connector  650 , actuator frame  660 , ball screw  680 , latch drive gear  930 , latch bearings  690 , tapered gib  460 , linear bearing rail  470 , and cable guides  670 . 
       FIG.  10    is a true section view through Section line B-B of  FIG.  4   . It shows latch rollers  520 , latch axles  730 , latch arms  510 , pillar axles  750 , latch pillars  550 , midplane plate  540 , spring housing  610 , jam nuts  620 , spring washer  590 , load sensor  580 , load sensor washer  570 , rear housing  420 , forward housing  410 , Hirth coupling  430 , pillar supports  450 , connector plate  630 , actuator rollers  640 , actuator axle  740 , electrical connector  650 , actuator frame  660 , ball screw  680 , latch drive gear  930 , latch bearings  690 , tapered gib  460 , linear bearing rail  470 , microswitch actuation surfaces  790 , and cable guides  670 . 
       FIG.  11    is an isometric section view through Section line C-C of  FIG.  4    which is through the centerline of the two alignment sockets  800 . It shows latch rollers  520 , latch axles  730 , latch arms  510 , latch pillars  550 , midplane plate  540 , spring housing  610 , jam nuts  620 , rear housing  420 , forward housing  410 , Hirth coupling  430 , connector plate  630 , actuator rollers  640 , electrical connector  650 , actuator frame  660 , ball screw  680 , and cable guides  670 . 
       FIG.  11    also shows motor  910  fastened to the motor mount plate  960  which is fastened to the geartrain housing  900  and connects to the motor output gear  940  which is supported by a motor bearing  950 . The motor bearing  950  is retained by the motor bearing plate  970 . The motor output gear  940  is in contact with, and drives, the idler gear  920  which is supported by the idler bearing  990  which is retained by the idler bearing plate  980 . 
     The microswitch tree  770  is fastened to the midplane plate  540  and supports several microswitches  760  which are used to sense the various positions of the actuator frame  660  by contacting specifically shaped microswitch actuation surfaces  790  on the actuator frame  660 . 
     The stiffener plate  860  is fastened securely to the forward housing  410  and the force moment sensor (FMS)  810  is secured to the stiffener plate  860 . The alignment sockets  800  are attached to the FMS plate  820  which is fastened to the FMS  810 . Within the alignment socket  800  are the spring bushing  830  which guides the spring  850  upon which rides the reaction washer  840 . 
       FIG.  12    is a true section view through section line C-C of  FIG.  4   . It shows latch rollers  520 , latch axles  730 , latch arms  510 , latch pillars  550 , midplane plate  540 , spring housing  610 , jam nuts  620 , spring washer  590 , load sensor  580 , load sensor washer  570 , rear housing  420 , forward housing  410 , Hirth coupling  430 , pillar supports  450 , connector plate  630 , actuator rollers  640 , actuator axle  740 , electrical connector  650 , actuator frame  660 , ball screw  680 , tapered gib  460 , linear bearing rail  470 , cable guides  670 , motor  910 , motor mount plate,  960  geartrain housing  900 , motor output gear  940 , motor bearing  950 , motor bearing plate  970 , idler gear  920 , idler bearing  990 , idler bearing plate  980 , microswitch tree  770 , microswitches  760 , stiffener plate  860 , FMS  810 , FMS plate  820 , spring bushing  830 , spring  850  and reaction washer  840 . 
       FIG.  13    is an isometric section view through section line D-D of  FIG.  4    primarily showing the linear translation elements of the at least one latch assembly  500 .  FIG.  13    also shows rear housing  420 , forward housing  410 , Hirth coupling  430 , midplane plate  540 , and the cable guide  670  which slides in the bushing  780 . The actuator frame  660  (see  FIG.  9   ) is fastened to the linear bearing platform  480  which slides on the linear bearing rail  470  which is secured to and aligned to the forward housing  410  by the tapered gib  460 . 
       FIG.  14    is a true section view through section line D-D of  FIG.  4   . It shows rear housing  420 , forward housing  410 , Hirth coupling  430 , midplane plate  540 , cable guide  670 , bushing  780 , geartrain housing  900 , linear bearing platform  480 , linear bearing rail  470 , and tapered gib  460 . 
       FIG.  15    is an end view on the active interface assembly  400  showing the general arrangement of the gear train and visible latch components. It shows the rear housing  420 , midplane plate  540 , motor  910 , motor mounting plate  960 , geartrain housing  900  and the two ball screws  680 . Arrayed symmetrically around each ball screw  680  are two cable guides  670 , each with a bushing  780 , and two latch pillars  550 , each with a sensor washer  570 , load sensor  580 , spring housing  610 , and a pair of jam nuts  620 . 
       FIG.  16    is a repeat of  FIG.  15    with the geartrain housing  900  and rear housing  420  removed to allow the gears to be visible. Shown are the motor  910 , motor mounting plate  960 , idler bearing plate  980 , idler bearing  990 , idler  920  that meshes with and drives the two latch drive gears  930  which are attached to the ball screw  680  and are supported by the latch bearings  690 . 
       FIG.  17    is a repeat of  FIG.  16    except at an isometric viewing angle and with the motor  910  and motor mounting plate  960  also removed for clarity. It shows the forward housing  410 , midplane plate  540 , idler bearing plate  980 , idler bearing  990 , idler  920 , latch drive gears  930 , ball screws  680 , latch bearings  690 , ball screws  680 , cable guides  670 , bushing  780 , latch pillars  550 , load sensor washers  570 , load sensors  580 , spring housing  610 , and jam nuts  620 . 
       FIG.  18    is an isometric view on the PIA  200  showing the passive housing  250 , 1 st  half of the Hirth coupling  210 , connector  280  fastened to the connector frame  220  which is attached to the connector bracket  290  which provides sufficient room for wiring (not shown), to exit behind the connector  280 . The latch ramps  230  and alignment pins  240  are fastened to the passive housing  250 . The passive housing is attached to the payload  130  (not shown) or spacecraft  120  (not shown) by housing fasteners  270 . 
       FIG.  19    is an isometric section view through line E-E of  FIG.  5    and shows passive housing  250 , Hirth coupling  210 , second half of the electrical connector pair  280 , connector frame  220 , connector bracket  290 , latch ramps  230 , alignment pins  240 , and housing fasteners  270 . 
       FIG.  20    is a true section view through line E-E of  FIG.  5    and shows passive housing  250 , Hirth coupling  210 , second half of the electrical connector pair  280 , connector frame  220 , connector bracket  290 , latch ramps  230 , alignment pins  240 , and housing fasteners  270 . 
       FIG.  21    is an isometric section view through line F-F of  FIG.  5    and shows passive housing  250 , Hirth coupling  210 , second half of the electrical connector  280 , connector frame  220 , connector bracket  290 , latch ramps  230 , and housing fasteners  270 . The ramp doublers  260  serve to reinforce the attachment of the latch ramp  230  to the passive housing  250 . 
       FIG.  22    is a true section view through line F-F of  FIG.  5    and shows passive housing  250 , Hirth coupling  210 , connector  280 , connector frame  220 , connector bracket  290 , latch ramps  230 , latch doublers  260 , and housing fasteners  270 . 
       FIGS.  23 A to  23 E  illustrate the sequence of events by which the AIA  400  aligns to the PIA  200  from the point at which the AIA  400  is manoeuvered into the capture envelope to the point immediately before the latch sequence is initiated.  FIG.  23 A  shows the AIA  400  in the approach mode at the lateral limit of the capture envelope. Ideally the AIA  400  will be more accurately aligned to the PIA  200  at this point, but the maximum lateral misalignment is shown to better illustrate the alignment functions of the low-profile manipulator interface system.  FIG.  23 B  shows the initial contact of the alignment pins  240  against the alignment sockets  800 .  FIG.  23 C  shows the AIA  400  moving towards the PIA  200  with the alignment pins  240  running against the conical surface of the alignment sockets  800  and becoming more aligned with the bore of the alignment sockets  800 .  FIG.  23 D  shows the alignment pins  240  positioned well within the bore of the alignment sockets  800  providing both lateral and angular alignment of the AIA  400  to the PIA  200 . The two Hirth couplings  210  and  430  have not yet come into engagement.  FIG.  23 E  shows the alignment pins  240  even further down the bore of the alignment socket  800  and the Hirth couplings  210  and  430  almost completely engaged. The latch assemblies  500  are nearly in a position to be engaged at this point. 
       FIGS.  24 A to  24 E  illustrate the sequence of events by which the latch mechanism structurally secures the AIA  400  to the PIA  200  and completes the electrical connections between the two sides of the interface.  FIG.  24 A  shows the mechanism in the unlatched condition and in approximately the same condition as shown in  FIG.  23 E  with the exception that the AIA  400  has come into full contact with the PIA  200 . The connector plate  630  and associated actuator rollers  640  are in the fully retracted position holding the latch arms  510  and associated latch rollers  520  also in their fully retracted position.  FIG.  24 B  shows the latch sequence starting with the connector plate  630  being extended (moving toward the PIA  200  in the Figure) and the actuator rollers  640  pushing the latch arms  510  outwards. At this point the latch rollers  520 , while not in contact with the latch ramps  230  do extend outwards to a point where the PIA  200  could no longer be withdrawn past them. In this condition the AIA  400  is considered to be “soft docked” to the PIA  200 . The connection is not sufficient to withstand significant structural loads or to make the electrical connections, but is sufficient to prevent the AIA  400  and PIA  200  from drifting apart should there be an event that stops the latching sequence. 
       FIG.  24 C  shows the latch sequence further advanced with the connector plate  630  moving toward the PIA  200  and the latch arms  510  further extended. It can be seen that the latch rollers  520  will soon contact the latch ramp  230 . 
       FIG.  24 D  shows the AIA  400  fully structurally latched to the PIA  200 . The actuator rollers  640  have forced the latch arms  510  to their most outward position forcing the latch rollers  520  not only into contact with the latch ramp  230 , but up the inclined surface of the latch ramp  230  such that the position of the latch arm  510  and latch pillar  550  are moved towards PIA  200 . This action compresses the Belleville springs  600  ( FIG.  8   ) exerting a force on the load sensor  580  ( FIG.  8   ) that verifies that the desired structural preload between the two assemblies has been achieved. The electrical connection has not yet been made. If no electrical connection is to be made to the PIA  200 , the latch sequence may halt here with the two assemblies structurally connected. 
     Where mating of the two halves of the electrical connector  650  and  280  is required, the connector plate  630  is further extended.  FIG.  24 E  shows the connector plate  630  positioned further towards PIA  200 . The actuator rollers  640  remain in full contact with the latch arms  510  but do not push them further apart, thus the preload does not change. The movement of the connector plate  630  towards PIA  200  forces the first half of the electrical connector  650  attached to the connector plate  630  into engagement with the second half of the electrical connector  280  attached to the connector frame  220  thus completing the electrical connection of the AIA  400  to the PIA  200  and also completing the latch sequence. 
       FIG.  25    is a block diagram illustrating the avionics interfaces within the system when the manipulator  100  is fully latched to the spacecraft  120  and not yet connected to the PIA  200  attached to a payload  130 . It also shows the avionics interfaces at that point while the manipulator  100  is transitioning from one PIA  200  on a Spacecraft  120  to a different PIA  200  on the same Spacecraft  120 . 
       FIG.  26    is a block diagram illustrating the avionics interfaces within the system when the manipulator  100  is fully latched to the spacecraft  120  and also fully latched to the PIA  200  attached to a Payload  130 . 
       FIG.  27    is a block diagram illustrating the avionics interfaces within the system while the manipulator  100  is transitioning from one PIA  200  on a spacecraft  120  to a different PIA  200  on the same spacecraft  120  where the manipulator  100  is fully latched to one PIA  200  on the spacecraft  120  and also fully latched to a different PIA  200  attached to the same spacecraft  120 . 
       FIGS.  28 A to  28 C  illustrate this alternate embodiment.  FIG.  28 A  shows the manipulator  100  manoeuvering an attached payload  130  fitted with a PIA  200  towards an AIA  400  fixed to the spacecraft  120 .  FIG.  28 B  shows the payload  130  releasably mated to both the manipulator  100  and the spacecraft  120 .  FIG.  28 C  shows the payload  130  now releasably mated to the spacecraft  120  with the manipulator  100  free to perform other tasks. 
       FIGS.  28 A to  28 C  illustrate an alternate embodiment where a payload  130  may be releasably attached to a spacecraft  120  using an AIA  400  attached directly to the spacecraft  120  mating to an additional PIA  200  attached to the payload  130 . 
       FIGS.  29 A to  29 D  show an additional embodiment where an assemblage of multiple payloads may be created using additional PIAs  200  and AIA&#39;s  400  attached to any number of payloads  130  and the spacecraft  130 . 
       FIG.  30    illustrates an embodiment where a sensor system, in this case a camera-based machine vision system, can be used to guide the PIA  200  into the capture envelope of the AIA  400 . 
     Method of Operation 
       FIG.  1    shows the spacecraft  120  with permanently fastened passive interface assembly PIA  200 , and containing a computer control system  300  which may communicate  150  with a ground station on earth  150  if required. The PIA  200  is releasably mated to a manipulator  100  that consists of an arm subassembly  110  and two active interface assemblies AIA  400 . The unmated AIA  400  at the distal end of the arm subassembly  110  is depicted approaching a payload  130  which is attached to some other object, not shown, which may be the spacecraft  120  or some other fixed location in space. The payload  130  also has at least one PIA  200  permanently fastened to it. 
     Both the spacecraft  120  and the payload  130  may have more than one PIA  200  fastened to them (see  FIGS.  28  and  29   ). In the case of a spacecraft  120  (which contains the computer control system  300  capable of controlling the entire manipulator  100 , including the attached AIAs  400 ) with more than one PIA  200 , the manipulator  100  may be commanded to sequentially mate to a different PIA  200  within reach on the spacecraft  120 , unmate the AIA  400  at the base of the manipulator  100  from its PIA  200  and then move the arm subassembly  110  so as to mate what was the base AIA  400  to yet another PIA  200  (not shown) located on the spacecraft  120  thus moving the manipulator  100  around the spacecraft  120  from one PIA  200  to a different PIA  200  permitting the reach of the manipulator  100  to be significantly extended. 
     In detail, to mate any AIA  400  to any PIA  200 , the computer control system  300  commands the arm subassembly  110  to move the unmated AIA  400  into proximity to the PIA  200 . Positioning the AIA  400  with sufficient accuracy to permit mating it to the PIA  200  may be accomplished in several ways, which include, but are not limited to autonomous control by the computer control system  300  or human-in-the-loop command from a remote location, possibly using communication  150  with a ground station  140 , using various sensors that may include cameras (illustrated in  FIG.  30   ), radar, LIDAR, etc. or the payload  130  may manoeuver the PIA  200  under the control of the payload  130  to within the capture envelope of the AIA  400 . For the purposes of explanation, further description will assume that the manipulator  100  is moving the AIA  400  to complete the mating function, however, it is possible for the PIA  200  on the payload  130  to be the portion of the interface that actually moves into contact with the AIA  400 . 
     The volume of space and the relative positions of the PIA  200  and the AIA  400  wherein a successful mating of the two halves of the interface may be achieved is termed the capture envelope. This capture envelope includes the relative positions, attitudes and motions of the AIA  400  and PIA  200  as well as several environmental factors such as temperature, and static electrical charge. If all elements of the defined capture envelope are met, a successful mating of the AIA  400  to the PIA  200  can be accomplished. It is a beneficial feature of the low-profile manipulator interface system that the means for mating of the AIA  400  to the PIA  200  are contained in the AIA  400  and controlled via the AIA  400  to PIA  200  connection at the base or shoulder of the manipulator  100 . This means that the payload  130  can be completely passive during the mating sequence, thus reducing the complexity of both the PIA  200  and the payload  130  it is fastened to, to the cost and mass benefit of both. 
       FIG.  30    illustrates one possible method by which the PIA  200  may be positioned within the capture envelope of the AIA  400 . The camera system  160  is electronically connected to machine vision software that forms part of the computer control system  300  (see  FIG.  25   ) and is used in conjunction with a target  180  that is configured to convey information about the relative positions of the camera system  160  and the target  180  when within the field of view  170  of the camera  160 . The machine vision software within the computer control system  300  uses the relative positions of the camera system  160  and the target  180  to compute the commands necessary to manoeuver the PIA  200  into the capture envelope of the AIA  400 . 
     The mating of the AIA  400  to the PIA  200  takes place in two main phases once the PIA  200  has entered the capture envelope of the AIA  400 . The first is the coarse alignment and contact, the second is fine alignment and latching. 
     Coarse Alignment and Contact 
     Referring to  FIG.  23 A , the AIA  400  is shown located within the capture envelope in the approach mode at the lateral limit of the capture envelope. There will also be some maximum angular misalignment permitted. Ideally the AIA  400  will be more accurately aligned to the PIA  200  at this point, but the maximum lateral misalignment is shown to better illustrate the alignment functions of the low-profile manipulator interface system. The alignment process to position the AIA  400  within the capture envelope is achieved through position control of the robotic arm  100 . 
     In one embodiment, the positioning of the AIA on the end of the robotic arm  110  is achieved through teleoperation control, whereby a remote operator, in the spacecraft  120  or controlling the arm from a remote ground control station  140  via radio communications  150  on earth specifies incremental position or rate commands via a motion input device such as a hand controller, based on visual feedback from a camera system  160  ( FIG.  30   ) showing views of a target  180  ( FIG.  30   ) located in a known position relative to the PIA  200 . Relative misalignment of the target with respect to a reticle shown on the centre of a remote control station TV screen is an indication of the translational or angular misalignment of the AIA alignment sockets  800  and the PIA alignment pins  240 . 
     In an alternate embodiment, a machine vision system can be used to guide the motion of the robotic arm  110 . Images of the target  180  from the camera system  160  are fed into computer vision software resident on the computer control system  300 . The relative pose (translational position and angular orientation) of the target  180  to the AIA  400  are computed using techniques such as photogrammetry or object recognition. This relative pose, which equates to the misalignment error, is used by the control system controlling the position of the distal end of the manipulator  100  to null the error and position the AIA  400  within the capture envelope. 
     Final assessment that the PIA  200  is within the capture envelope of the AIA  400  can be established by several means that include, but are not limited to computed knowledge of where the AIA  400  is relative to the PIA  200 , based upon sensors  122  in various parts of the arm subassembly  110  and measurements made during manufacture or calibrated once in service, mechanical touch probes attached to either the AIA  400  or PIA  200 , cameras and precisely aligned targets either attached to the AIA  400  and PIA  200  or cameras  126  based on the spacecraft  120  with sufficient resolution to establish positions. 
     With the PIA  200  within the capture envelope of the AIA  400 , the computer control system (CCS)  300  commands the arm subassembly  110  to move the AIA  400  attached to the free end of the arm subassembly  110  closer to the PIA  200 . Because it is within the capture envelope, the motion commanded by the CCS  300  is in a direction parallel with the longitudinal axis of the alignment sockets  800 . As shown in  FIG.  23 B , initial contact of the alignment pins  240  is against the conical opening of the alignment sockets  800 . The forces that result from this contact are sensed by the force moment sensor (FMS)  810  at the base of each alignment socket  800  and fed back to the CCS  300  which modifies the motion command of the robotic arm and AIA  400  so as to minimise moments about axes orthogonal to the insertion axis and forces lateral to the alignment socket  800  while continuing to push the alignment sockets  800  progressively on to the base of the alignment pins  200 . 
     One such method for controlling forces and moments during this type of insertion process is described in Results of Human-in-the-Loop Testing of the Force/Moment Accommodation Feature Using the Special Purpose Dexterous Manipulator Ground Test Bed, Lymer, J.; Mukherji, R., 30th International Conference on Environmental Systems, 2000. Iteratively manoeuvering the AIA  400  to minimise the forces has the effect of moving the AIA  400  into successively better alignment with the PIA  200  as the distance between the two assemblies diminishes.  FIG.  23 C  shows the AIA  400  moving towards the PIP  200  with the alignment pins  240  running against the conical surface of the alignment sockets  800  and becoming more aligned with the bore of the alignment sockets  800 . Once the alignment pins  240  are centred within the long bore of the alignment sockets  800  the coarse alignment of the AIA  400  to the PIA  200  is complete. 
     The  FIG.  23 D  does show an idealised state. In reality perturbations and imprecisions in the motion of the arm subassembly  110  will mean that the alignment pins  240  will continue to contact the sides of the bore of the alignment socket  800  throughout this phase of the mating sequence. The CCS  300  will act to actively minimise these contacts while also being programmed to not cause excessive motion in the arm subassembly  110  in attempts to find an optimal solution. 
     As described thus far, the alignment socket  800  imposes predominantly moment loads upon the FMS  810  which it then transmits to the CCS  300 . These loads are transmitted mechanically through the FMS plate  820  which connects the alignment socket  800  to the FMS  810 . Once the alignment pin  240  is at nearly the full depth of the bore of the alignment pin  240  a means is needed to sense and control the final contact between the AIA  400  and the PIA  200 . As shown in  FIGS.  12  and  23   , just before the point of final contact of the two Hirth couplings  210  and  430  the tip of the alignment pin  240  will contact the reaction washer  840  which then compresses the spring  850  which runs within the spring bushing  830 . This contact produces a longitudinal force upon the FMA plate  820  that is transmitted to the FMS  810 . This allows the FMS  810  to sense both the moments generated along the bore of the alignment socket  800  and the longitudinal forces generated when the reaction washer  840  is contacted by the alignment pin  240 . The stiffener plate  860  provides a sufficiently stiff connection between the alignment socket  800  and the forward housing  410  so that the FMS  810  may generate correct readings. 
     It should be noted that in an alternate embodiment of the AIA, a full force-moment sensor  850  will not be incorporated. Instead the force and moment sensing required to perform the coarse alignment described in  FIGS.  23 B to  23 D  will be performed by an independent force and moment sensor located in between each end of the arm sub-assembly  110  and the AIAs  400 . In this application, the FMS  810  in the AIA can be replaced with a simpler contact sensor indicating that the tip of alignment pins  240  have reached a sufficient travel down the alignment sockets  800 . The force control system for the robot arm sub-assembly will use this alternative force-moment sensor to control contact forces which result during the coarse alignment of the AIA  400  and the PIA  280 , noting its different position within the overall robot manipulator system  100  topology. With the alignment pins  240  in contact with the reaction washers  840 , the arm subassembly  110  continues to move the AIA  400  closer to the PIA  200  until the two Hirth couplings  210  and  430  come into contact. This contact is sensed by the series of microswitches  440  placed peripherally about the circumference of the forward housing  410 . These microswitches  440  indicate contact between the two halves of the interface. Their position around the periphery of the contact surfaces provides sensing that the contact is uniform around the circumference and that the contact is suitable to initiate the latch sequence. At this point the coarse alignment and contact phase is complete. 
     Fine Alignment and Latching 
     Once the coarse alignment and contact phase is complete, the AIA  400  performs the fine alignment and latching sequence to complete the process of mating to the PIA  200 . Referring to  FIGS.  24 A,  7 ,  8 , and  20   ,  FIG.  24 A  shows the mechanism in the unlatched condition and is approximately the same condition as shown in  FIG.  23 E  with the exception that the AIA  400  has come into sufficient contact with the PIA  200 . The two Hirth couplings  240  and  430  are in sufficient and even contact as sensed by the alignment pin  240  having depressed reaction washer  840  sufficiently to generate the correct contact force on the FMS  810  and the four microswitches  440  having been activated to indicate all-round contact. At this point there may still remain some small gap and rotational misalignment between the Hirth couplings  240  and  430 . The connector plate  630  and associated actuator rollers  640  are in the fully retracted position holding the latch arms  510  and associated latch rollers  520  also in their fully retracted position. 
     At this point the CCS  300  commands the motor  900  to turn thereby driving the motor output gear  940  (shown in  FIGS.  11  and  12   ) which thereby turns the idler gear  920  which, in turn, simultaneously drives the two latch drive gears  930  which are attached to the two ball screws  680 . With the latch drive gears  930  longitudinally fixed in the AIA  400  by the two idler bearings  990 , rotating the latch drive gears  930  has the effect of forcing the shaft of the ball screw  680  to move forwards or backwards along the long axis of the ball screw  680 . The shaft of the ball screw  680  is connected to the base of the actuator frame  660  and rotationally fixed to the actuator frame  600  by the use of the keyed bushing  700  which, because the actuator frame  660  is rotationally fixed to the linear bearing platform  480  and linear bearing rail  470  prevents the shaft of the ball screw  680  from rotating. Therefore, the rotation of the base of the ball screw  680  forces the shaft of the ball screw  680  to move longitudinally. When the shaft of the ball screw  680  moves towards the pia  200 , it forces the connected actuator frame  660  and connector plate  630  to move forward as well. 
     In order for the CCS  300  and any human controllers to understand the positions of the various components during the latch sequence, sensors are used to establish the position of the actuator frame  660 . A plurality of microswitches  760  are supported on the microswitch tree  770  and each generates a signal as the microswitch  760  is tripped by engaging the various microswitch actuation surfaces  790  that are formed into the surface of the actuator frame  660  (see  FIG.  11   ). While microswitches  760  are used in this embodiment, other linear sensors such as potentiometers and resolvers can be used instead to provide similar sensing of the position of the actuator frame  660  and thereby knowledge of the state of the latch assembly  500 . 
     Attached to the connector plate  630  are the actuator rollers  640  which rotate around the actuator axles  740  and are supported by actuator needle bearings  710  to permit free rotation. The actuator rollers  640  are in constant and close contact with the latch arms  510  on the latch cam surfaces  350  which are shaped specifically to impart the desired motion in the latch arms  510 . As the actuator rollers  640  are pushed further towards the PIA  200  by the extending shaft of the ball screw  680 , the actuation rollers  640  push the latch arms  510  outwards. 
     The latch arms  510  are secured to the latch pillars  550  by the latch axles  730  and rotate about the latch axles  730 . The latch pillars  550  are free to move longitudinally and are supported in the midplane plate  540  by the pillar bushings  560 . Restricting the longitudinal motion of the latch pillars in the midplane plate  540  are the Belleville springs  600 , protected by the spring housing  610  and retained by the jam nuts  620 . The Belleville springs  600  bear upon the spring washer  590 , which serves to even out the concentrated load from the Belleville springs  600 , which then bears upon the load sensor  580  which is calibrated to sense the forces moving the latch pillar  550  through of the midplane plate  540 . The load sensor  580  sits upon the load sensor washer  570  which evens out the load distribution seen by the load sensor  580 . The load sensor  580  is connected to the CCS  300  which uses the forces sensed to control the latching sequence. 
     At the point shown in  FIG.  24 B  the latch arms  510  have started to move and the latch rollers  520 , while not in contact with the latch ramps  230  do extend outwards to a point where the PIA  200  can no longer be withdrawn past them. The connection is not sufficient to withstand significant structural loads or to make the electrical connections, but is sufficient to prevent the AIA  400  and PIA  200  from drifting apart should there be an event that stops the latching sequence at that point. 
       FIG.  24 C  shows the latch sequence further advanced with the connector plate  630  moved towards the PIA  200  in the Figure) and the latch arms  510  further extended. It can be seen that the latch rollers  520  will soon contact the latch ramp  230 . 
     Once the latch arms  510  have been extended to the point where the latch rollers  520  contact the latch ramp  230  the connector plate  630  continues to extend towards the PIA  200  pushing the latch rollers  520  further outwards. This additional outwards movement of the latch rollers  520  forces the latch rollers  520  up the inclined plane of the latch ramp  230 . The inclined surface of the latch ramp  230  is shaped such that as the latch rollers  520  move outwards along them the PIA  200  is forced towards the AIA  400  thus forcing the two Hirth couplings  240  and  430  together completing the fine alignment of the AIA  400  to the PIA  200  and creating the desired preload that acts to prevent the two halves of the interface from separating under operating loads. The preload force is reacted through the latch arms  510 , to the latch pillar  550  which via the jam nuts  620  and spring housing  610  compresses the Bellville springs  600  allowing the latch pillar  550  and latch arms  510  to move a small distance towards the PIA  200  compared to the unlatched position, in which the base of the latch pillar  550  is in contact with the midplane plate  540 . The compression of the Belleville Springs  600  exerts a force on the load sensor  580  in direct relation to the amount of movement of the latch pillar  550  and latch arms  510  caused by the latch rollers  520  moving up the inclined plane of the latch ramp  240 . When the Belleville Spring  600  forces on the load sensor  580  achieve a pre-established level, the desired preload between the two halves of the interface have been achieved. 
       FIG.  24 D  shows the AIA  400  fully structurally latched to the PIA  200 . The actuator rollers  640  have forced the latch arms  510  to their most outwards position forcing the latch rollers  520  not only into contact with the latch ramp  230 , but up the inclined surface of that latch ramp  230  such that the position of the latch arm  510  and latch pillar  550  have been moved towards the PIA  200 . 
     As of this point the latch sequence is structurally complete but the electrical connection has not yet been made therefore the latch is considered to be partially “hard docked”. If no electrical connection is to be made to the PIA  200 , the latch sequence may halt here with the two assemblies structurally connected. In fact, if electrical connections are not required, the PIA  200  in this case may not contain electrical connectors  280 , connector frames  220  or connector brackets  290 . 
     If making electrical connections between the AIA  400  and PIA  200  is desired then the connector plate  630  is further advanced towards the PIA  200 . The shape of the latch cam surface  350  is such that this continued advancement of the connector plate  630  does not push the latch rollers  520  further outwards and thus the preload forcing the AIA  400  and PIA  200  together does not change. The connector plate  630  continues to be advanced until the connector  650  contacts the mating connector  280  and engages, making the electrical connection. 
       FIG.  24 E  shows the connector plate  630  having advanced further towards the PIA  200  and having completed mating of the electrical connection. The actuator rollers  640  remain in full contact with the latch arms  510  but do not push them further apart, thus the preload has not changed. The movement of the connector plate  630  towards the PIA  200  forces the connector  650  attached to the connector plate  630  into engagement with the connector  280  attached to the connector frame  220  thus completing the electrical connection of the AIA  400  to the PIA  200 . 
     Once the latch sequence is complete no further power is required to maintain the structural and electrical connection between the AIA  400  and PIA  200  because the shape of the latch cam surface  350  is such that at that point the forces generated by the preload mechanism are in equilibrium and do not act to cause the connector plate  630  to retract or reduce the preload. 
     To disconnect or demate the PIA  200  from the AIA  400 , the above sequences are run in reverse. The motor  910  is commanded to rotate the opposite direction as before, the shaft of the ball screw  680  retracts away from the PIA  200  bringing with it the connector plate  630  and actuation rollers  640 . This causes the connectors  280  and  650  to separate, and then the latch arms  510  to withdraw towards each other first allowing the latch rollers  520  to move down the inclined plane of the latch ramp  230 , thus removing the preload, and then move away from the latch ramps  230  entirely, eventually moving sufficiently that the lip of the latch ramps  230  is no longer obstructed by the latch rollers  520  and the AIA  400  may be freely withdrawn from the PIA  200  by the CCS  300  commanding the motion of the arm subassembly  110 . 
     Additional Embodiments 
     The foregoing description of the preferred embodiments of the disclosure has been presented to illustrate the principles of the disclosure and not to limit the disclosure to the particular embodiment illustrated. It is intended that the scope of the disclosure be defined by all of the embodiments encompassed within the following claims and their equivalents. 
     The preferred embodiment disclosed uses two Latch Assemblies  500 , however only one is necessary for the invention disclosed to operate correctly. In this embodiment two have been used to leave room between them for additional tools or sensors to be affixed to the AIA  400  to perform additional tasks. 
     Additionally, greater force and moment loads or greater economies of scale may be achieved by using more than two latch assemblies  500 . 
     The current embodiment also uses the Hirth style coupling to react rotational loads and moments at the interface between the AIA  400  and the PIA  200 . Other styles of couplings, such as curvic couplings or “dogs and slots”, may be used if advantageous. 
     It will be understood that the definition of “spacecraft” and “payload” in this disclosure is based upon which of the objects being attached to the manipulator  100  contains the CCS  300  that is actually controlling the manipulator  100 . Another embodiment would have a CCS  300  in each of two spacecraft and that control of the manipulator  100  and attached AIAs  400  passes from one CSS  300  to another as operations demand, the role of payload  130  and spacecraft  120  exchanging depending upon which CCS  300  is actually controlling the manipulator  100  at the time. In such a manner a manipulator  100  may transfer from one spacecraft to another as well as from location to location about a single spacecraft. 
     While it maximises the utility of the manipulator  100  to have it releasably mounted on a PIA  200  affixed to the spacecraft  120 , the low-profile manipulator interface system works equally well if it is part of a manipulator  100  that is permanently attached to a spacecraft. 
     Similarly, the actual presence of a manipulator  100  or arm subassembly  110  is not necessary for the low-profile manipulator interface system to function as long as there exists a means to perform the “coarse alignment” of the AIA  400  into sufficiently close proximity of the PIA  200  such that the latch assembly  500  can engage the features on the PIA  200  and create the proper preload between the AIA  400  and PIA  200 . With a suitably compliant mounting system, the low-profile manipulator interface system could be used to berth payloads  130  to one or more storage locations on the spacecraft  120 , each fitted with a permanently attached AIA  400 . In this embodiment, an AIA  400  is mounted directly to the surface of the spacecraft without an attached arm subassembly  110  and a payload  130  is manipulated such that the payload manipulation means performs the movement needed to achieve the coarse alignment and contact sequences at which time the AIA  400  mounted to the spacecraft  120  performs the fine alignment and latching sequences to secure the payload  130  to the spacecraft  120 . The payload  130  manipulation means may include, but is not limited to, another manipulator  100  mounted to the spacecraft  120  or to a different spacecraft. 
       FIGS.  28 A to  28 C  illustrate this alternate embodiment.  FIG.  28 A  shows the manipulator  100  manoeuvering an attached payload  130  fitted with a PIA  200  towards an AIA  400  fixed to the spacecraft  120  via coupling interface  602 .  FIG.  28 B  shows the payload  130  releasably mated to both the manipulator  100  and the spacecraft  120 .  FIG.  28 C  shows the payload  130  now releasably mated to the spacecraft  120  with the manipulator  100  free to perform other tasks. Given a notional payload  130  with a PIA  200  on one side and an AIA  400  on another side and electrical connections between the PIA  200  and AIA  400 , it would be possible to stack payloads  130 , one after another, in a string, from a single AIA  400  mounted on a manipulator  100  or spacecraft  120 , thus forming, in effect, a train of payloads  130  which would act rigidly and could be used as building blocks for a larger assembly. Once created, this string or train or assemblage of payloads  130  may be disengaged from the AIA  400  connecting it to the CCS  300 , the said assemblage then being free to be used for any other purpose. In such a way, assemblages may be made in space that serve as entirely new spacecraft, as storage facilities, as structural components in other larger structures in space or on a surface, the low-profile manipulator interface system essentially being the fasteners that hold the various pieces together. 
       FIG.  29 A to  29 D  illustrate this alternate embodiment showing a series of payloads  130  releasably mated to each other using a plurality of AIAs  400  and PIAs  200  fixed to each payload  130  and to a spacecraft  120 .  FIG.  29 A  shows the PIA  200  on a first payload  130  being moved towards an AIA  400  about to be berthed to the spacecraft  120 .  FIG.  29 B  shows a payload  130  now releasably mated to the spacecraft  120  and an additional payload  130  being manoeuvered in anticipation of being mated the payload  130  currently releasably mated to the spacecraft  130 .  FIG.  29 C  shows an additional payload  130  having been mated to the previous two creating a larger assemblage,  FIG.  29 D  shows the larger assemblage of payloads  130  with the manipulator  100  attached to a PIA  200  on the assemblage, and having been released by the spacecraft-mounted AIA  400 , being moved away from the spacecraft  130 . While the illustrations depict a linear assemblage of payloads  130 , it may be appreciated that by positioning the various PIAs  200  on various surfaces of the various payloads  130 , that the resulting assemblage may be of virtually any shape or size. 
     It is also possible to create a latch mechanism that provides more than one preload between the AIA  400  and PIA  200 . By varying the angle of inclined plane of the latch ramp  230 , the extension stroke of the latch arm  510  and varying the shape of the latch cam surface  350 , the latch assembly  500  can be made to apply different preloads when mated to different PIAs  200 . This would permit PIAs  200  to be created with preloads better tailored to the needs of the connection being created so that connections seeing lighter loadings can have lighter and cheaper PIAs  200  than connections that see more severe loads. A single AIA  400  would be able to engage these more and less strong PIAs  200  by varying the stroke of the ball screw  680  connected to the connector plate  630 . 
     In an alternate embodiment (not shown in  FIG.  30   ), the target  180  can be mounted inside the PIA  200  on the same mounting surface as the alignment pins  240  with the camera system mounted inside the ring formed by the hirth coupling  430  on the AIA  400 , such that the viewing centre line of the camera is coincident with the centre of the target. 
     Finally, while the apparatus, system and method associated with the PIA  200  and AIA  400  have been taught for spacecraft assembly and servicing operations as described above, the design could be used in non-space applications where robot based relocation or the picking up of robot payloads such as factory automation or nuclear inspection and maintenance. Any PIAs  200  being used as additional base locations of the manipulator would need to be supplied with power and data connections to some central computing function much like the spacecraft CCS  300 .