Refueling tool and refueling tool embedded system

Abstract

The present disclosure relates to a robotically controlled satellite refueling tool and associated robotically controlled support and site preparation tools that facilitate remotely operated on-orbit refueling of fill / drain valves of various designs and sizes on satellites not originally prepared for on-orbit servicing through the installation of quick-connect safety valves using vision-based feedback and feedback from sensors embedded in the refueling tool to operate an adaptable and adjustable mechanism suite. The refueling tool has an open architecture that allows the refueling tool vision system to view the fill / drain valves and sections of the refueling tool engaged with the fill / drain valves. The support tools include a blanket cutter tool, a blanket handler tool, a wire cutter tool, and a gripping tool, and the site preparation tools include a B-nut removal tool and a crush seal removal tool. Each of these tools includes a common base structure interfaced to the end effector of a robotic arm to transmit rotation and torque to the various tools.

Description

[Technical field]

[0001] The present disclosure relates to methods, systems, and tools for safely accessing and opening and closing fill / drain valves of satellites during on-orbit propellant refueling operations. More specifically, the tools are designed for propellant refueling of satellites that are designed for refueling as well as satellites that are not originally prepared for refueling. The present disclosure is specifically designed to facilitate propellant refueling of satellites that are not originally prepared for refueling after an initial refueling due to components left on the satellite during the initial refueling. [Background technology]

[0002] Many currently operational satellites were designed with a finite amount of propellant in mind, not the possibility of propellant being refueled. The design philosophy relied on replacing the satellite after exhausting its on-board propellant supply. Considering the cost of replacing a satellite, the ability to refuel satellites that are either near the end of their life but are otherwise functional, or that have experienced an insertion anomaly or have been maneuvered further than originally intended for planned operation, would be highly advantageous, thereby extending their operational life by several or even many years. It is estimated that as many as half of all GEO communications satellites will end their 10-15 year lifespan with all or most of their subsystems still functional, forcing the retirement of the satellite only by the depletion of a carefully budgeted propellant payload. Using current economic models, the ability to refuel these end-of-life satellites in one mission would extend their respective useful lives by three to five years, thereby delaying the need to expend the very high capital costs of launching replacement satellites. Some satellites suffer a primary propulsion system failure or a failure related to the launch vehicle's upper stage shortly after launch. In these cases, the entire book value must be written off and compensation paid to the operator by the insurer. The satellite becomes the insurer's asset and must eventually be disposed of in a graveyard or re-entry orbit. If one of these assets could be refueled with propellant, allowing it to be moved to an orbital station in geosynchronous orbit, extending its life by 5 to 10 years, most or all of the spacecraft's value could be recovered.

[0003] In addition, new long-endurance satellite concepts have been proposed, where modular satellites consist of a base structure supporting power generation, guidance, control, and payload modules, some or all of which can be replaced or added over a lifespan that may be significantly longer than that of current satellites. These satellites would benefit not only from an initial replenishment of propellant, but also from repeated resupply missions over many years of operation.

[0004] A key technical issue is that these satellites are not designed for robotic servicing, and it is not generally accepted that such a mission is technically possible. Specifically, most satellites are designed with propellant fill and drain valves (or FDVs) that are intended to be filled once prior to launch and never opened or manipulated again. Thus, remotely accessing these FDVs in-orbit would present several major challenges, and would include several tasks, each difficult to accomplish robotically: cutting and removing the protective thermal blanket, removing several lock wires that are hand wrapped around the valve, unscrewing and removing the outer and inner valve caps, coupling the fuel fill line to the valve nipple, mechanically actuating the valve, and replacing the inner valve cap once propellant refueling is complete. In-orbit servicing has been the subject of much research over the past 30 years. The idea of ​​maintaining space assets, rather than discarding and replacing, has attracted a variety of ideas and programs. So far, the concept has only found a home in manned space programs where it has been met with some success in the Solar Max and Hubble Space Telescope repair missions, the Palapa B2 and Westar rescue missions, and the assembly and maintenance of the International Space Station.

[0005] Robotic capture and servicing of an operational geostationary orbit spacecraft has never been demonstrated before. Until recently, no technology had been disclosed that could solve the problem of accessing the propulsion system of an unprepared satellite for the purpose of resupplying the propellant holding station. The majority of artificial satellites in orbit today were not designed with orbital propellant refueling in mind, and access to the propulsion system is designed to be accessed by humans on Earth prior to launch. The technology required to access the propulsion system of a client spacecraft for the purpose of resupplying propellant is still at a very low technology readiness level and is generally considered to be the main obstacle to successful servicing missions.

[0006] Transferring fuel used for spacecraft propulsion systems from one source to another is highly hazardous due to the corrosive and explosive nature of the liquids involved. For example, inadvertent mixing of fuel and oxidizer in a bipropellant system will cause immediate combustion, so liquid transfer systems for bipropellant-based fuels must ensure that accidental mixing does not occur. It would be highly advantageous to provide a system of tools designed to open and close various types / sizes of satellite FDVs during propellant refueling operations on unprepared satellites, including but not limited to removing sealing cap assemblies, connecting / disconnecting propellant hoses to client satellites, and installing new sealing cap assemblies, to name just a few.

[0007] Existing satellite FDVs come in several design forms with different dimensions and concepts of operation. Therefore, to maximize the economic benefits of such a propellant refueling system, the minimum number of tools with the minimum mass should be carried on any given mission to allow refueling of the widest selection of FDV designs using a single tool. Further mass and operational advantages arise if visual means can be used to assess and control various aspects of the refueling tool function, as opposed to relying on a limited host of sensors.

[0008] Further advantages can be realized if the resupply system can better accommodate the largest possible constellation of FDVs on the satellites being resupplied, exemplified by being able to accommodate the smallest possible spacing between FDVs.

[0009] U.S. Patent No. 8,074,935 issued to Greiniewski et al. on December 13, 2011, discloses a system and method for refueling an unprepared satellite from a servicing spacecraft, including a robotic arm, suitable tools that can be attached to the end effector of the robotic arm required to access, open and close the fuel fill valves on the satellite to be serviced, and a storage and retrieval station for the tools and a tool container in which the various fuel fill valve caps are stored. Several unobtrusive sockets are included for the different sized components that make up the fill and drain valves that must be removed before the refueling operation and replaced after refueling. While engaging with the removable mechanism of the fill and drain valve (FDV), the sockets cover the entire part that is removed. In addition, this refueling tool could not accommodate variations in the vertical / longitudinal axis position of the removable or actuable mechanism of the various fill and drain valves to be serviced.

[0010] U.S. Patent No. 9,567,111 issued to Roberts et al. discloses a system and tool for accessing the fill / drain valves during propellant refueling of a client satellite by a servicer satellite. The device uses two to three cam wrenches that fit onto the FDV, one wrench engages the immovable flats and the other engages the rotatable features of the removable valve components. The advantage of this system is that it provides an inherent torque balance through the use of a differential gearbox. The wrenches are also configured to accommodate a wide range of torque mechanism sizes and shapes (reaction flats, hex, round with flats, square) and are designed with a 2x torque margin.

[0011] A drawback of both of the above systems is that the valve and tool are generally hidden, so the tool status or valve status is not sensed. The cam wrenches in the latter system work as two opposing pairs operating at two heights on different sized mechanisms, relying on a complex hinge engagement caused by the rotating contact of the cams as they close against the valve body at the base and the actuating nut at the higher position. The engagement of both pairs of cam wrenches can only occur simultaneously because they are driven in opposite directions via a differential that can only generate torque by one pair of cam wrenches acting against the other. The strengths of this approach are its ability to accommodate a wide range of sizes and shapes, and its inherent torque balance, but it also makes it impossible to determine when exactly the engagement began to occur, or if it has actually begun to occur, so the exact status of the FDV mechanism cannot be determined. New information from one FDV supplier has pointed out that excessive rotation of the actuating nut in the opening direction can lead to failure of the actuating nut retention mechanism, which can subsequently lead to the actuating nut being unintentionally removed, and the generation of uncaptured debris. As a result, new requirements have been made regarding the maximum rotation of the actuating nut to not be exceeded. This translates directly into the need for enhanced valve state sensing. Summary of the Invention

[0012] Disclosed herein are systems and apparatus that facilitate remote on-orbit refueling of FDVs of various designs and sizes for satellites not originally prepared for on-orbit servicing through the installation of quick connect safety valves using vision- and sensor-based feedback to operate a suite of adaptable and adjustable mechanisms.

[0013] 1. A method for transferring a fluid from a servicer spacecraft to a client spacecraft, the client spacecraft including a tank and a fill and drain valve coupled to the tank, the fill and drain valve including a valve actuation nut for opening and closing the fill and drain valve, the fluid being selected from the group consisting of a fuel and an oxidizer; a. removing an access valve cap of the fill and drain valve; b. providing sensory confirmation that the removal operation was successful; and c. establishing a fluid connection between a safety valve of the servicer spacecraft and a source of propellant; d. providing a sensory confirmation that the connection has been established; and e. attaching the safety valve to the fill and drain valve to provide a safety fluid coupling that allows fluid to flow into the fill and drain valve but does not allow fluid to flow out of the fill and drain valve; f. providing sensory confirmation that the relief valve is installed; g. opening the fill and drain valve by actuating the valve actuation nut; h. providing sensory confirmation that the actuation nut has been actuated; i. directing a robotic arm of the servicer spacecraft to transfer fluid through the safety valve and into the tank.

[0014] The steps b), d), f), and h) of providing sensory confirmation may be accomplished using a combination of feedback provided by real-time visual images and feedback from strategically placed sensors to monitor and sense the position of the access valve caps, the safety valves, fluid lines, the fill and drain valves, and the valve actuation nuts.

[0015] 1. A method for refueling a client satellite by accessing one or more fill and drain valves in fluid communication with one or more propellant storage tanks disposed on the client satellite, comprising: a) one or more safety valves; b) a refueling tool having a refueling tool vision system including at least one camera, a rotatable wrench, and an open architecture structure, such that when the refueling tool is engaged with a fill / drain valve, the field of view of the camera encompasses the engaged fill / drain valve, the rotatable wrench of the refueling tool, and a coupling nut of a safety valve installed on the fill / drain valve, and including sensors strategically positioned on selected moving components of the refueling tool to sense the position of the selected moving components during a refueling operation; c) a set of support tools for preparing the client satellite to receive the refueling tool and for assisting in the refueling operation, a) a robotic arm attached at its proximal end to the servicer spacecraft; b) a tether for fixedly connecting the client satellite to the servicer spacecraft; and c) a propellant transfer system for transferring propellant from the servicer spacecraft to the client satellite; and d) the method of refueling is performed using the servicer spacecraft having a propellant coupling attached to an end effector connected to the propellant transfer system for transferring propellant to the client satellite through the propellant coupling; The method of refueling comprises: a) maneuvering a servicer satellite into close proximity with said client satellite and using a tethering device to fixedly tether said client satellite to said servicer satellite; b) directing the robot arm to sequentially capture the tool and the support tool to loosen and remove any objects covering the fill / drain valve, thereby exposing the fill / drain valve, whereupon any objects are removed, retracting the tool and exposing the fill / drain valve; c) directing the robotic arm to capture the refueling tool configured to establish a fluid connection between the safety valve and a propellant tank of the servicer spacecraft after the fill and drain valve is exposed, and once captured, directing the robotic arm to capture a safety valve, thereby connecting the propellant transfer system to the safety valve; d) directing the robotic arm to place the safety valve on a refueling nipple of the fill and drain valve based on real-time visual images obtained by the refueling tool vision system and feedback from one or more sensors; e) transferring the propellant through the tool and a safety valve to the client satellite; f) once the propellant has been transferred, directing the robotic arm to disconnect the refueling tool from the fill / drain valve thereby disconnecting the propellant transfer system; g) detaching the tether from the client satellite.

[0016] The method may include recording an output of the one or more sensors.

[0017] The sensors may be one or more microswitches, one or more potentiometers, or any combination thereof.

[0018] The sensor may be a microswitch and the feedback from one or more microswitches is the state of the microswitch at that particular time during the refueling operation.

[0019] The microswitch may be located within a mechanism tasked with positioning the safety valve on the fill / drain valve to sense the safety valve during capture and to sense a safety valve coupling nut of the safety valve contacting the refueling nipple of the fill / drain valve during a refueling operation.

[0020] The present disclosure provides a system mounted on a servicing spacecraft for transferring a fluid to a client satellite, the client satellite including a tank and a fill and drain valve, the tank coupled to the fill and drain valve, the fill and drain valve having an actuation nut for opening and closing the fill and drain valve, and an access valve cap on the fill and drain valve; a. a fluid transfer means for transferring a fluid from a fluid tank of the servicing spacecraft to the tank of the client satellite, the fluid being selected from the group consisting of fuel and oxidizer; b. tool means for removing and replacing said access valve cap, for connecting and disconnecting fluid lines to and from said fill and drain valve, and for actuating said valve actuation nut to open and close said fluid valve; c. a first sensing means for determining a relative displacement between said tool means and said fill / drain valve; d. second sensing means for determining a state of said fill and drain valve during subsequent steps of accessing and manipulating said fill and drain valve and then connecting and disconnecting said fill and drain valve from a fluid line; e. a safety valve attachable to said fill / drain valve to provide a safe fluid coupling with said safety valve having one or more independent seals against leakage during and after refueling; f. positioning means connectable to said tool means for positioning said tool means relative to said fill / drain valve; g. providing a system comprising: control means in communication with said first and second sensing means, said positioning means, and said tool means for controlling operation of said positioning means and said tool means based on feedback from said first and second sensing means.

[0021] The tool means comprises: a first tool operable to loosen the access valve cap and open and close the valve actuation nut to connect and disconnect fluid lines to and from the fill and drain valve; and a second tool for removing the access valve cap.

[0022] The tool means may include a third tool for removing a crush seal from the fill and drain valve.

[0023] The first sensing means may be a vision system arranged to have a field of view to monitor the relative displacement between the tool means and the fill / drain valve.

[0024] The second sensing means is a vision system positioned to have a field of view that encompasses a working space including the first and second tools engaged with the fill and drain valve; and sensing means embedded in said tool means for sensing and recording the position of a selected moveable component during a fluid transfer operation.

[0025] The present disclosure provides a refueling tool mounted to a servicing spacecraft for opening and closing one or more fill / drain valves of a client satellite being refueled with the one or more fill / drain valves in fluid communication with a fuel tank of the client satellite, the one or more fill / drain valves having rotatable and static mechanisms coaxially aligned along a first axis, the servicer spacecraft including a safety valve and the safety valve that is mounted to and stowed at the fill / drain valve during refueling prior to passing fuel through the fill / drain valve, and further including a refueling system configured to be coupled to the safety valve during a refueling operation; a) a refueling tool structure comprising a mechanism A for aligning and clamping to the fill / drain valve body and torque reaction plane of a target fill / drain valve; 1. A rotatable wrench comprising: A mechanism B1 for opening and closing the rotatable wrench; a mechanism B2 for rotating the wrench, to which the mechanism B1 for opening and closing the wrench is attached in a dependent manner; and a mechanism C for adjusting the height of the rotatable wrench, a rotatable wrench, said mechanism B2 being attached to mechanism C, and optionally said mechanisms A, B1, B2 and C forming a substructure forming a torque reaction loop ensuring that torque induced by rotating said rotatable wrench is reacted in said valve body via said torque reaction plane; b) a mechanism D for connecting the refueling system to a refueling nipple of the engaged target fill and drain valve, the mechanism D being connected to the base structure and to a top plate which is connected to the base structure by a side plate to form an overall refueling tool structure; an end effector interface connected to the top plate and configured to grasp and mate with a robot end effector attached to a robot arm attached to the servicer spacecraft; one or more sensors disposed within mechanism D for sensing the safety valve during capture and sensing a safety valve coupling nut of the safety valve contacting the refueling nipple of the fill / drain valve during a refueling operation; a tool vision system including at least one camera attached to the refueling tool structure, wherein the undercarriage has an open architecture such that when the refueling tool engages a fill / drain valve, a field of view of the at least one camera encompasses the engaged fill / drain valve, the rotatable wrench of the refueling tool, and a coupling nut of the safety valve, as during the refueling operation, and the state of all of the rotatable wrench, the fill / drain valve, and the safety valve can be sensed and / or monitored using a combination of microswitch states and real-time images from the at least one camera.

[0026] The sensor may be a microswitch and the feedback from one or more microswitches is the state of the microswitch at that particular time during the refueling operation.

[0027] The sensor may be one or more microswitches, one or more potentiometers, or any combination thereof.

[0028] The present disclosure provides a system for refueling a client satellite, the system comprising: a) a servicing spacecraft, a robotic arm attached at its proximal end to the servicer spacecraft; and an end effector attached to a distal end of the robotic arm; a tethering system for fixedly tethering the client satellite to the servicer spacecraft; a propellant transfer system; a propellant coupling attached to the end effector coupled to the propellant transfer system for transferring propellant through the propellant coupling to the client satellite; a control system in communication with the robotic arm, the end effector, the propellant transfer system, and the refueling tool to control the refueling operation based on feedback from a sensor system and the at least one camera; a communications system for remotely communicating with the servicer spacecraft; The Servisa spacecraft to which the b) the servicer spacecraft, the refueling tool; one or more safety valves, the one or more safety valves being installed at the fill / drain valve during refueling prior to passing fuel through the safety valve and the fill / drain valve, the propellant coupling being configured to couple to the one or more safety valves, the one or more safety valves being configured to be picked up by and coupled to the end effector; a set of site preparation tools configured to be picked up by and coupled to the end effector, the site preparation tools configured to perform selected tasks to prepare the client satellite to receive the refueling tool; a set of refueling support tools configured to be picked up by and coupled to the end effector, the refueling support tools configured to engage the fill / drain valve to prepare the fill / drain valve to receive the safety valve; the servicing spacecraft housing the A system is provided comprising:

[0029] The present disclosure provides a suite of support tools for preparing a client satellite for refueling, comprising: a set of tools, each having a specific function, each tool having a drive shaft and a tool section configured for that specific function; a common tool base to which each of said set of tool tips is permanently attached, a housing having a gripping interface on one side thereof configured for robotic gripping by an end effector mounted on a distal end of a robotic arm mounted on a servicing satellite, the gripping interface including a grapple fixture, and a housing having a tool mounted on its other side configured to receive the drive shaft of the tool; two tool mechanism drive interfaces used to perform any tool tip function via drive actuator mechanisms located on the end effector of the robot arm, one of the two tool mechanism drive interfaces being used to drive a specific tool tip of each of the support tools and the second one being used to drive a constraint storage mechanism for holding the common base when not being grasped by the robot arm; a tool mechanism gear train disposed within the housing for transmitting rotation and torque from one of the tool mechanism drive input interfaces to the tool drive shaft via a tool mechanism gear train interface for actuation of a tool function; and a common tool base including a constraint mechanism "active half" that is coupled to and driven by the second tool mechanism drive interface for use in holding the common base to the constraint mechanism when not in use and separated from the end effector.

[0030] The restraint mechanism includes a receptacle housing secured to the servicing spacecraft that receives the tool held on the common base and has a passive locking mechanism configured to engage and lock with the restraint mechanism "active half" of the common base.

[0031] The common base and the receptacle housing include visual cues that visually assist the robotic arm in aligning the common base with the receptacle housing during the operation of inserting and locking the common base into the receptacle housing.

[0032] The suite of support tools may include site preparation tools each including a common base and a tool tip attached thereto, each tool tip having a specific apparatus operation, the tool tip common structure including a housing having an interface configured to be bolted to the common base, a female threaded drive shaft having a portion extending from the housing that is inserted into the common base for engaging one of the two mechanism drive interfaces, a forward male threaded rod threadably mounted on a portion of the drive shaft located inside the housing, and a series of input linkages and a series of output linkages located at a distal end of the common structure, wherein rotation of the drive shaft causes linear movement of the forward threaded rod which in turn moves the series of input linkages which in turn pivots a pivotally connected output linkage forming part of the apparatus operation mechanism about a specific point on any tool tip to open or close the apparatus operation mechanism depending on the direction of movement.

[0033] The support tool may be a thermal blanket shear device such that the operating mechanism of the device is a pair of cutting shears integrally formed with a distal end of the output pivot connection output linkage to provide a cutting action.

[0034] The support tool may be a thermal blanket handling device such that the motion mechanism of the device is a pair of blanket paddles integrally formed with the distal end of the output pivot connection output linkage to provide a gripping action for gripping and removing thermal blanket pieces.

[0035] The support tool may be a wire cutter and gripping tool, such that the operating mechanism of the device is a pair of wire cutter shears having a wiring gripping mechanism integrally formed with the distal end of the output pivot connection output linkage to provide a gripping action for gripping and severing wire.

[0036] The support tool suite may include a crash seal removal tool for removing a crashed seal created when a fill / drain valve B nut is removed, the crash seal removal tool including the common base and a crash seal removal tool tip attached thereto, the crash seal removal tool tip including an interface configured to be bolted to the common base, a female-threaded rotatable drive shaft having a portion inserted into the common base to engage one of the two mechanism drive interfaces, and a male-threaded plunger partially received in the female-threaded drive shaft and movable relative thereto, the plunger having a distal plunger face including a pair of flex jaw linkages pivotally connected together with a pivot point, the flex jaw linkages each having a distal flex jaw tip, the flex jaw linkages each having a distal flex jaw tip, and the flex jaw linkages each having a distal flex jaw tip, ... A flex jaw linkage extends through an opening in a cage that is fixedly attached to a tool tip base structure, and as the drive shaft rotates, a plunger moves rearward into the drive shaft, and as the plunger moves, the pivot point of the flex jaw linkage moves with the plunger, closing and retracting the flex jaw tip, contacting a valve stem of the fill / drain valve and retracting along the fill / drain valve stem, the flex jaw tip is preloaded against the fill / drain valve stem, hooks onto the crush seal, and retracts until it is released by a force where it is trapped in the cage between the flex jaw tip and the distal plunger face, and rotation of the drive shaft in the reverse direction opens the flex jaw tip and pushes the plunger face forward, ejecting the crush seal from the tool tip.

[0037] The support tool suite may include a B nut removal tool including a common base and a B nut removal tool tip permanently attached thereto, the B nut removal tool tip including a tool tip base structure permanently attached to the common base, a drive shaft having a portion inserted into the common base for engaging one of the two mechanism drive interfaces, spring wrench fingers coupled to a distal end of the drive shaft, and a collet having a keyed connection to the spring wrench fingers at a proximal end of the spring fingers to allow movement only along an axis of rotation of the drive shaft, the collet having a slot in an outer diameter of the collet and surrounded by a pin carrier housing and including a cam pin attached to the pin carrier housing extending within the slot, the pin carrier housing being engaged at a ratchet disk interface by a preload spring, wherein rotation of the ratchet disk is limited by a keyed mechanism between the ratchet disk and the tip base structure. Due to the delay from rotation by the ratchet disk via preloading against the pin carrier housing, in order for the pin carrier housing to rotate with the drive shaft, the collet must move axially forward whilst driven by the cam pin of the pin slot until the end of the pin slot forces the collet to close the spring fingers on the B nut against the hexagonal feature of the B nut and continued drive shaft rotation causes the pin carrier housing to rotate, the collet encircling the spring fingers and B nut whilst the preload force of the preload spring of the ratchet disk interface is overcome allowing the pin carrier housing surface with the ramp feature to repeatedly slide over the ratchet disk surface with the ramp feature, whereby the collet can be retracted by unscrewing the B nut from the FDV and reversing the rotation of the drive shaft allowing the spring fingers to open so that the B nut is no longer contained and can be discarded. [Brief description of the drawings]

[0038] An embodiment of a mechanism for remote operation of a satellite FDV will now be described, by way of example only, with reference to the following drawings: [Figure 1] A typical arrangement of an FDV 54 on an FDV bracket 52 is shown. [Figure 1A] FIG. 13 is a cross-sectional view through the lower body 56 of the FDV in a region including the torque reaction plane 58, which is the region where alignment of the FDV occurs via feature A12. [Figure 1B] A side view of FDV54 is shown. [Figure 1C] The individual mechanisms of FDV are shown. [Figure 1D] 1 shows the components that cap the valve. [Diagram 2] FIG. 1 is a perspective view of the refueling tool 10 aligned and positioned with the FDV 54 in preparation for refueling. [Figure 2A] FIG. 1 is a perspective view of the refueling tool 10 aligned and positioned with the FDV 54 in preparation for refueling. [Figure 3A] FIG. 12 is a perspective view of mechanism A12. [Figure 3B] 1 is an underside view partially sectioned to show the arrangement of jaws 121, rollers 123 and gripper 125. FIG. [Figure 4A] 1 is a cross-sectional view of mechanism A12, including tension assembly 113 and drive link 116, rocker 117 and connecting link 118. FIG. [Figure 4B] 1 is a cross-sectional view of mechanism A12, including tension assembly 113 and drive link 116, rocker 117 and connecting link 118. FIG. [Figure 4C] 1 is a cross-sectional view of mechanism A12, including tension assembly 113 and drive link 116, rocker 117 and connecting link 118. FIG. [Figure 5A] FIG. 11 is a series of images collectively demonstrating the suitability of Mechanism A12 and illustrating the self-centering motion inherent to Mechanism A, correcting the initial large lateral offset prior to final seating of contact finger 126 on valve body 32 and torque reaction plane 34. [Figure 5B] Collectively, the suitability of mechanism A12 is demonstrated, showing the closed configuration with small valve body 32 in both parallel and vertical orientations. [Figure 5C] Collectively, the suitability of mechanism A12 is demonstrated, showing the closed configuration with small valve body 32 in both parallel and vertical orientations. [Figure 5D] Collectively, they demonstrate the suitability of mechanism A12 and show a closed configuration with a large valve body 32. [Figure 5E] Collectively, they demonstrate the suitability of mechanism A12 and show a closed configuration with a large valve body 32. [Figure 5F] The closed configurations are shown with the larger valve body in both parallel and vertical configurations. [Figure 5G] The closed configurations are shown with the larger valve body in both parallel and vertical configurations. [Figure 6A] FIG. 11 is a perspective view of a mechanism B114. [Figure 6B] FIG. 11 is a perspective view of a mechanism B114. [Figure 6C] FIG. 13 is an exploded view showing details of the B1 actuator mounting arrangement. [Figure 7A] FIG. 13 is an orthogonal projection view of mechanism B114. [Figure 7B] This is a folded cross section that passes through all the centers of rotation. [Figure 8A] FIG. 13 is a cross-sectional view of mechanism B1 showing the spring plunger associated with the automatic wrench closure stop mechanism. [Figure 8B] FIG. 13 is a cross-sectional view of mechanism B1 showing the spring plunger associated with the automatic wrench closure stop mechanism. [Figure 8C] FIG. 13 is a cross-sectional view of mechanism B1 showing the spring plunger associated with the automatic wrench closure stop mechanism. [Figure 8D] The gear train of mechanism B1 is shown. [Figure 9A] FIG. 2 is a perspective view of a compliance mechanism 16. [Figure 9B] FIG. 13 is a perspective view of compliance mechanism 16, including its relationship with mechanism B114. [Figure 10A] FIG. 2 is an orthogonal projection view of the compliance mechanism 16. [Figure 10B] FIG. 2 is an orthogonal projection view of the compliance mechanism 16. [Figure 10C] FIG. 2 is an orthogonal projection view of the compliance mechanism 16. [Figure 11A] FIG. 13 is a perspective view of mechanism B218. [Figure 11B] FIG. 13 is a perspective view of mechanism B218 including its relationship with compliance mechanism 16. [Figure 12A] FIG. 2 is an orthogonal projection view of mechanism B218. [Figure 12B] FIG. 2 is an orthogonal projection view of mechanism B218. [Figure 12C] FIG. 13 is a cross-sectional view of mechanism B218. [Figure 12D] FIG. 13 is a cross-sectional view of mechanism B218. [Figure 13A] Mechanism B218 is shown having compliance mechanism 16 and mechanism B114 at the clockwise and counterclockwise limits of travel. [Figure 13B] Mechanism B218 is shown having compliance mechanism 16 and mechanism B114 at the clockwise and counterclockwise limits of travel. [Figure 14A] FIG. 13 is a perspective view of mechanism C20. [Figure 14B] FIG. 13 is a perspective view of feature C20 including its relationship with feature B218. [Figure 15] 13 shows a different perspective view of mechanism C20 illustrating the area where mechanism A12 is attached to mechanism C20. [Figure 16A] 1 shows a safety valve. [Figure 16B] 1 shows conceptually the internal components of a safety valve. [Figure 17] A perspective view of mechanism D22 is shown. [Figure 18] 13 shows a different perspective view of feature D22 including its relationship to feature C20. [Figure 19] FIG. 13 is an exploded view of mechanism D22. [Figure 20] FIG. 13 is an exploded view of mechanism D22. [Figure 21] FIG. 2 is an exploded view of the transmission 26. [Figure 22] FIG. 22B is a top view of the transmission 26, with FIG. 22B showing a cross section through the input gear stack. [Figure 23A] Each of the four gears in the transmission 26 is shown. [Figure 23B] Each of the four gears in the transmission 26 is shown. [Figure 23C] Each of the four gears in the transmission 26 is shown. [Figure 23D] Each of the four gears in the transmission 26 is shown. [Figure 24] FIG. 4 is a cross-sectional view of the refueling tool 10 below the top plate 479. [Diagram 25] 1 is a top view of refueling tool 10 with a cutaway view revealing transfer gear 508 for first rotary input shaft 502. [Figure 26] 1 is a cross-sectional view of transmission 26 showing input gear 454 and quill shaft 509, with a further cutaway showing transmission lead screw 484. [Figure 27] 1 illustrates the concept of a robot end effector that is appropriately equipped to perform all of the maintenance tasks described herein. [Figure 28] 1A-1C show perspective and cross-sectional views of various independent support tools used by the servicer spacecraft to prepare the client satellite for refueling. [Figure 29] 1A-1C show perspective and cross-sectional views of various independent support tools used by the servicer spacecraft to prepare the client satellite for refueling. [Diagram 30] 1A-1C show perspective and cross-sectional views of various independent support tools used by the servicer spacecraft to prepare the client satellite for refueling. [Diagram 31]1A-1C show perspective and cross-sectional views of various independent support tools used by the servicer spacecraft to prepare the client satellite for refueling. [Diagram 32] 1A-1C show perspective and cross-sectional views of various independent support tools used by the servicer spacecraft to prepare the client satellite for refueling. [Diagram 33] 1A-1C show perspective and cross-sectional views of various independent support tools used by the servicer spacecraft to prepare the client satellite for refueling. [Diagram 34] 1A-1C show perspective and cross-sectional views of various independent support tools used by the servicer spacecraft to prepare the client satellite for refueling. [Diagram 35] 1A-1C show perspective and cross-sectional views of various independent support tools used by the servicer spacecraft to prepare the client satellite for refueling. [Diagram 36] 1A-1C show perspective and cross-sectional views of various independent support tools used by the servicer spacecraft to prepare the client satellite for refueling. [Figure 37] The left panel shows a perspective view and the right panel shows a cross-sectional view of the site preparation tool tip including the blanket cutter tool 650. [Figure 38] The left panel shows a perspective view and the right panel shows a cross-sectional view of the site preparation tool tip including blanket handling tool 652. [Figure 39] The left panel shows a perspective view and the right panel shows a cross-sectional view of the site preparation tool tip including the wire cutter tool 654. [Diagram 40] Shown are perspective views of a B-nut removal tool tip used to remove the B-nut on an FDV prior to refuelling, with the left panel showing the tool fully assembled and the right panel showing the tool partially disassembled to reveal some of the internal components. [Diagram 41]A partial perspective view is shown on the left panel, showing a full cross-section taken from a perspective view of the B nut removal tool tip prior to engagement with the FDV. [Diagram 42] A partial perspective view is shown on the left panel, showing a full cross section taken from a perspective of the B nut removal tool 608 during the stages of movement once it has engaged the B nut on the FDV. [Diagram 43] A partial perspective view is shown on the left panel, showing a full cross section taken from a perspective of the B nut removal tool 608 during the stages of movement once it has engaged the B nut on the FDV. [Diagram 44] A partial perspective view is shown on the left panel, showing a full cross section taken from a perspective of the B nut removal tool 608 during the stages of movement once it has engaged the B nut on the FDV. [Diagram 45] A partial perspective view is shown on the left panel, showing a full cross section taken from a perspective of the B nut removal tool 608 during the stages of movement once it has engaged the B nut on the FDV. [Diagram 46] FIG. 7 is a perspective view of a crush seal removal tool tip 700 for removing a crush seal. [Figure 47] Various elevation views (upper panels) and associated cross-sectional views (lower panels) taken along the section lines of a crush seal removal tool tip 700 are shown. [Figure 48] Various elevation views (upper panels) and associated cross-sectional views (lower panels) taken along the section lines of a crush seal removal tool tip 700 are shown. [Figure 49] Various elevation views (upper panels) and associated cross-sectional views (lower panels) taken along the section lines of a crush seal removal tool tip 700 are shown. [Figure 50] Various elevation views (upper panels) and associated cross-sectional views (lower panels) taken along the section lines of a crush seal removal tool tip 700 are shown. [Figure 51]FIG. 13 is a perspective view of an embodiment of a tool restraint mechanism disposed over an associated tool restraint receptacle. [Figure 52] FIG. 52 is a cross-sectional view from FIG. 51 of the tool restraint mechanism. [Figure 53] FIG. 52 is a cross-sectional view from FIG. 51 of the tool restraint mechanism. [Figure 54] FIG. 1 is a system diagram showing a servicer satellite tethered to a client satellite being refueled, illustrating the various support tools required to access the FDVs sequestered on the servicer satellite. [Figure 55] 1 illustrates a non-limiting illustrative example of a computer control system that may be used to control the operation of a robotic tool. [Figure 56A] 1 is a block flow diagram detailing the steps taken by a servicer spacecraft 80 when engaged with a client satellite 81 during a refueling operation. [Figure 56B] 1 is a block flow diagram detailing the steps taken by a servicer spacecraft 80 when engaged with a client satellite 81 during a refueling operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Various embodiments and aspects of the present disclosure are described with reference to the details discussed below. The following description and drawings are illustrative of the present disclosure and are not to be construed as limiting the present disclosure. The drawings are not necessarily to scale. Numerous specific details are described in order 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 the embodiments of the present disclosure.

[0040] As used herein, the terms "comprises" and "comprising" are to be interpreted as inclusive, open-ended, and not exclusive. Specifically, as used herein, including the claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps, or components are included. These terms are not to be interpreted as excluding the presence of other features, steps, or components.

[0041] 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.

[0042] As used herein, the terms "about" and "approximately," when used in conjunction with dimensional ranges of particles, mixture compositions, or other physical attributes or characteristics, are meant to cover slight variations that may exist at the upper and lower limits of the dimensional range, so as to not exclude embodiments where, on average, most dimensions are met, but statistically the dimensions may fall outside this region. It is not intended to exclude such embodiments from the present disclosure.

[0043] FDV work site, 50 1, 1A, and 1B show a typical geometric arrangement of FDVs 54 with minimum spacing. FIG. 1A shows an arrangement where a first pair of FDVs are vertically aligned and 2.25 inches apart, and a second pair of FDVs are also vertically aligned and 2.25 inches apart. The first and second vertically aligned pairs are spaced horizontally 2 inches apart in a symmetrical staggered pattern. Note that at the base of each FDV valve body 56 and above the level of the mounting screw heads are a pair of torque reaction planes 58, with the mid-plane between the planes aligned with one of the three mounting screws. As shown in FIG. 1A, the close spacing of the fill and drain valves 58 creates a restricted access envelope through which a service robot arm refueling tool can be positioned to access the FDV 58 features. 1C illustrates the relevant features of the FDV 54: the B-nut 64 (also known as the valve access cap), the actuation nut 62, the valve body 56 with torque reaction flat 58, the mounting flange 66, and the welded connection 68 that is completed upon installation. FIG. 1D is an exploded view of the FDV showing the FDV nipple 70 and the components that cap the valve, the B-nut 64, and the crush seal 702.

[0044] Because the mounting hole pattern is evenly spaced, each FDV can be mounted in one of three possible orientations, and the final mounting configuration is not a matter of record. As a result, there are three possible orientations of the torque reaction plane in each example valve. Each of the three possible orientations would be satisfactory to the technician during initial installation, but some may be trickier than others, making them possible, albeit unlikely. A detailed examination of each possible orientation at each of the four locations reveals that the automated system must be able to accommodate a torque reaction plane that is either parallel or perpendicular to the refueling tool's approach direction. Relying on only one of these two relative orientations, rather than either possibility, would result in the system being unable to reliably grasp the torque reaction plane of any valve in any possible installation configuration.

[0045] Also note that there are two separate designs of valves in the arrangement shown, with both the valve body diameter and transverse dimensions differing between the two designs. This is typical of bipropellant systems where the two valve sizes actually differentiate the fuel and oxidizer circuits by employing different sized threaded connections, further reducing the slight risk of accidental mixing during fueling at the launch pad by attaching the fuel line to the oxidizer circuit, or vice versa. This presents an additional challenge to mechanism A12, whose function is to align and clamp to the valve body and reaction planes so that torque applied by the wrench rotation mechanism can be reacted on the valve body and prevented from being transmitted to the FDV mounting bracket or welded tube connection 68.

[0046] Refueling Tool Vision System Based Open Architecture, 40 To be insurable, no single point of failure must prevent the mission from succeeding, so the robotic operator of a refueling payload must be able to verify successful completion of each task or have the ability to continue the mission under degraded conditions.

[0047] Refueling operations can be divided into two scenarios: 1. Initial alignment of the Refueling Tool (RT) 10 to the FDV, e.g. Using an external camera, a remote operator or an automatic control system can help guide the motion of the robot arm holding the RT to the starting condition at the work site, i.e., the RT touching down on the spacecraft deck. 2. Working with tools while on the FDV, for example: · To identify the vertical alignment of the tool reaction mechanism using the B-nut or working nut of the FDV. · To identify when the tool reaction mechanism is engaged with the FDV B-nut or working nut and verify that the FDV mechanism has actually rotated.

[0048] The operator should always have a minimum of two options for perceiving each task, which achieves the following: Gives the operator confidence that what they see in the camera view is supported by secondary sources of information i.e. torque measurements, RPMs, switches, robot arm force moment sensor (FMS) outputs, etc. In out-of-range conditions (lighting, obstacles, camera anomalies, reflections) additional information is immediately available.

[0049] Based on the trade studies performed, it became apparent that the fundamental primary sensing during the alignment operation was the camera, as the only reliable way to confirm alignment to the target FDV is through a visual display. This led to an open architecture solution, where the tool volume around the FDV is left open to allow access for the camera view. When properly implemented with complementary tools, the same refueling tool vision system based solution to ensure initial alignment of the refueling tool to the FDV is ideal for continuously monitoring the status of the FDV.

[0050] The present disclosure is designed around the primary requirements for a refueling tool vision system based sensing as the primary source of operator feedback to demonstrate the various access, alignment, clamping actions of the refueling tool, and the ability to demonstrate the rotational state of the FDV B nut and actuation nut, including, but not limited to, initial coarse alignment and preparation for alignment, successful alignment to the valve body and torque reaction plane, initial wrench alignment to the hex mechanism in both rotation and height, successful rotation of the hex mechanism, confirmation of safety valve capture, initial alignment of the safety valve coupling nut to the FDV, inclusion of contact confirmation, and confirmation of advancement of the safety valve coupling nut in the FDV threaded connection.

[0051] Implementation of a refueling tool visual system based sensing in geosynchronous orbit requires a camera appropriate for the task, environment, and journey to orbit. Video equipment tends to be sensitive to extreme temperature ranges, radiation exposure, and other aspects of the environment, requiring extensive quality assurance testing to demonstrate suitability for this application. Most video equipment is designed for commercial or industrial applications and will require repackaging or rework for additional shielding and / or material substitution to meet the requirements of the geosynchronous environment. This means that the range of qualified video equipment available for design is limited, and the highly miniaturized video equipment commonly present, especially in handheld computers, is unlikely to be suitable for use in geosynchronous orbit, now or in the foreseeable future. Qualified equipment tends to be large compared to their comparable counterparts in the consumer market.

[0052] Managing multiple video streams would also be challenging in that environment, requiring video switching equipment built specifically for the task, resulting in another overhead for any approach involving a large number of cameras.Thus, this design is based on a single working camera view, with the critical characteristic that the single camera view must have a fully redundant backup.

[0053] Designing the camera view behavior leads directly to the device having to operate almost entirely in the background of the image relative to the target FDV, so that the FDV mechanism can always be seen and the view is not obstructed or overly shadowed. For this reason, twisting from the far side of the camera view using an open-end wrench, for example, has advantages over twisting from above using a socket.

[0054] The present disclosure is illustrated in Figures 2 and 2A. The refueling tool 10 is depicted in the process of servicing one of four FDVs 54 arranged in a symmetrical pattern on a typical FDV bracket 52. Note that one of the four FDVs 54 is shown midway through the refueling operation, with the B-nut being removed and the safety valve 350 about to be installed. The cameras 42 under the camera shield 46 are positioned on the camera bracket 44 such that each camera has a full view of the work site and all interactions between the refueling tool and the target FDV. Alternatively, the primary and redundant camera pairs can be implemented with a single lens and beam splitter, thus providing an ideal view for each camera, rather than each camera having a compromised view for the other cameras.

[0055] The camera shown represents a vision system in a broader sense. The entire refueling tool vision system may be as simple as a single camera aimed at a human operator, or may comprise a suite of optical sensors including, but not limited to, cameras, lidars, and laser range finders that are more suited to an automated machine vision based system. In addition, a single camera may be used in conjunction with detailed optical surveys performed by other tools or devices on a robotic arm, such that the camera view relates the tool position to the target FDV in a computer-generated 3D rendering. In this sense, the refueling tool vision system based architecture encompasses any optical system used in conjunction with a human or machine operator to demonstrate the continuous status of the refueling operation.

[0056] Also seen in FIG. 2 are four contact spheres 490, one on each of two touchdown rods 491 and two touchdown arms 492, one of the touchdown rods attached to the camera bracket 44 and the other attached to the touchdown bracket 493, the purpose of the contact spheres being to indicate contact between the refueling tool and the FDV bracket 52 via force / moment sensing and control within the robotic arm 84 or other means. The contact spheres, touchdown rods and arms shown are representative of a means of touchdown sensing, although other technologies may alternatively be employed including, but not limited to, proximity sensing and sensing by mechanical actuation of a switch by either direct or indirect means.

[0057] 2A also shows elements of refueling tool end effector interface 500: gripping fixture 501, first rotary input shaft 502, second rotary input shaft 503, electrical connector 504, and quick connect nipple 505. The refueling tool is essentially a collection of mechanisms, each with a specific function: mechanism A 12 for aligning and clamping to valve body 56 and torque reaction plane 58, mechanism B 114 for opening and closing the wrench, mechanism B 218 for rotating the wrench, mechanism C 20 for adjusting the height of the rotating wrench, and mechanism D 22 for connecting the refueling system to the nipple of the target FDV. Each mechanism requires one independent actuation, with the exception of mechanism D, which requires two.

[0058] Mechanism B1 for opening and closing the wrench is attached dependently to mechanism B2 for rotating the wrench, which in turn is attached to mechanism C for raising the wrench. Mechanism A for aligning and clamping to the valve body is also attached to mechanism C. This substructure forms a torque reaction loop, ensuring that the torque induced by rotating the wrench is reacted on the valve body via a torque reaction plane as required. This substructure is connected to mechanism D, which includes the refueling delivery system and refueling tool top plate 479, and includes an end effector interface by bolt and pin connections to side plate 483, thus forming the entirety or structure of the refueling tool assembly.

[0059] The need for multiple separately controlled actuations, especially when each requires a separate actuator, may be viewed as a disadvantage to this design approach since the drive electronics for the separate actuators would be located on the robot arm and the associated interconnections would pass through separate electrical connectors on the robot arm and the refueling tool end effector.

[0060] The end effector of the robotic arm optimally has two external tool drives, as the majority of the tools used in the total refueling operational concept are passive external drives that require one tool drive input for stowing and unstowing and a second tool drive input for mechanism operation; passive tools (site preparation and refueling support tools described below) include, but are not limited to, those that cut and manipulate thermal blankets, cut and remove lockwires, and remove B-nuts and crush seals.

[0061] To minimize the number of separate actuators, associated drive electronics, and separable electrical interconnects, a transmission 26 movably positioned adjacent the refueling tool end effector interface is used to selectively direct a first end effector rotary drive shaft 502 to one of four separate outputs, one each for mechanism A, mechanism B2, mechanism C, and mechanism D. A second end effector rotary drive shaft 503 is used to actuate the transmission, which actuation selects which mechanism is connected to the first tool drive input. The power transmission may optionally include additional mechanisms for effecting additional actuation within the refueling tool, such as docking and undocking the refueling tool.

[0062] Each of the aforementioned features, as well as other elements of the present disclosure, are further described in the following paragraphs.

[0063] Mechanism A, Alignment and Clamping, 12 3A, 3B, and 4A and 4B, Mechanism A is driven in a closing motion by clockwise rotation of the input shaft 102 supported between a lower thrust ball bearing 103 and an upper thrust needle roller bearing 104, the former being selected due to the high thrust load induced by clamping Mechanism A, and the latter being selected due to the relatively low thrust load involved in driving the mechanism through free space to a fully open position. The clockwise rotation induces an upward movement of the tension assembly 113, which comprises a tension housing 105, a lead nut 106, a piston 107 with a cross pin 108, a spring 109, spacers 110 and 111, an end cap 112, and a linear bearing rail 114. The cross pin 108 passes through slots on both sides of the tension housing 105. A linear bearing block 115 mounted on the Mechanism A frame 128 guides the movement of the tension assembly 113 and maintains alignment with the input shaft 102. A spring 109 located between the end cap 112 and the piston 107 allows continued upward movement of the tension assembly after the rest of the mechanism contacts the valve body and movement stops; such continued movement is used to compress the spring to create a predetermined level of clamp load.

[0064] Vertical movement of the tension assembly induces horizontal movement of a push rod 119 via a drive link 116, a rocker arm 117, and a connecting link 118, with the drive link 116 connected to the cross pin 108. The push rod 119 is guided into a bushing 120 contained within a mechanism A frame 128. The mechanism A frame 128 forms the structural framework for aligning the refueling tool 10 to the FDV axis 60 via a mechanism A mounting interface 129.

[0065] Mechanism A jaws 121 rotate about pivot 122 housed within body 128 and are driven symmetrically closed by rollers 123 contained within roller brackets 124 as the roller brackets are driven forward towards the target FDV by connection to push rods 119. Rollers 123 roll within closure slots within jaws 121 such that the rollers drive the jaws in both closed and open directions, the closure slots being shaped to produce a fast closing motion in a stroke region apportioned to centering and then much slower in a stroke region devoted to clamping, this latter region being designed to accommodate FDV bodies of various sizes and orientations. The slower closing motion in this stroke region devoted to clamping provides a better mechanical advantage to roller brackets 124.

[0066] Jaws 121 each include two gripping portions 125 that are free to rotate through approximately 10 degrees. Each gripping portion has two contact fingers 126, and when the jaws close around the base of FDV 54, one finger of each gripping portion contacts the cylindrical surface and the other contacts the torque reaction plane 58 of valve body 56. This arrangement allows the grippers to close around a range of valve body diameters in two different orientations, with the torque reaction plane parallel to Mechanism A pushrod and the torque reaction plane perpendicular to Mechanism A pushrod, as depicted in Figures 5A, 5B, 5C, 5D, 5E, 5F, and 5G.

[0067] Primary and redundant microswitches 127 mounted on the tension assembly 113 change state from closed to open once the spring 109 reaches the desired compression, and the switch notifies the operator of the latched state.

[0068] Mechanism B1, wrench close / open, 14 6A, 6B, 6C, 7A, 7B, 8A, and 8B, mechanism B1 is a wrench opening / closing device based on twin lead screws 150 with right and left threads on opposite ends in a parallel screw clamp arrangement, with like oriented threads on each side of the assembly, with the right threads on the actuator side. Two wrench jaws 154, each housing two like oriented lead nuts 155, are attached to the threads of a corresponding lead screw on each side of mechanism B1, with the wrench jaws configured such that the location where the wrench jaws intersect the FDV axis 60 is on a line formed by the center of the lead screw. Each lead nut 155 is held by a nut clamp 156, and the lead nuts are free to rotate within the wrench jaws and nut clamp during initialization to establish the parallel arrangement of the wrench jaws. The lead nuts are then locked against rotation by drilling a hole through the nut clamp, lead nut, and wrench jaws and installing a locking pin 157.

[0069] The need for the actuation of B1 to be independent of the motion of the other mechanisms, most notably the rotation of the wrench, combined with the complexity of the motion of the B1 actuation axis provides ample justification for a separate actuator for this mechanism.

[0070] The mechanism B1 housing 152 and B1 cover 153 surround the central gear 151 of each lead screw via bearings 172, one on each housing and cover, and surround the two idler gears 158 via idler shafts 173 and idler bearings 174. The B1 drive input gear 159 is supported via a pair of bearings 172 arranged side-by-side in the cover, so that the shaft of the drive input gear can be exposed through an opening in the B1 housing. Referring to FIG. 7A, the B1 drive input gear has a torque reaction recess 175 on the exposed drive shaft that is precisely manufactured to receive the torque reaction shaft 176 of the B1 drive actuator 160, the torque reaction recess in this embodiment being in the form of a shaft with flat surfaces. The mechanism B1 housing 152 provides a unique mounting arrangement for the B1 drive actuator 160, which is coaxially mounted on a puck-shaped adapter 161 made of a self-lubricating material. The adapter is placed and contained within a corresponding recess 162 in the mechanism B1 housing 152 and is held therein by two retaining clips 163. The adapter is fitted with two pins 164 oriented radially on opposite sides of the adapter such that the pins are coaxial. The B1 housing actuator recess 162 has cutouts to accommodate the radially opposed pins and allow the pins to rotate the actuator adapter by approximately 15 degrees. After installation, two spring plunger assemblies each comprising a plunger guide 165, a compression spring 166, and a plunger 167 with a bifurcated head 168 are positioned tangentially to the B1 housing actuator recess 162 with the bifurcations straddling the radially opposed pins such that both spring plunger assemblies apply a counterclockwise torque to the actuator adapter as viewed from the end of the actuator on the opposite side of the actuator axis.When the wrench jaws are closed on the object or reach the end of travel in the closing direction, the torque forces the radially opposed pins to seat into one end of the B1 actuator recess notch, and the collective engagement and retention of the actuator adapter within the B1 actuator recess, in conjunction with the positioning of the spring plunger assembly, allows the actuator, which is attached to the adapter by the radially opposed pins, to rotate clockwise within the B1 housing actuator recess against the tangentially disposed spring plunger.

[0071] One of the spring plungers with a bifurcated head 168 interacts with a pair of microswitches 169 which close when the spring plunger is fully extended and open when the spring plunger is compressed, with the actuator being commanded to stop when the microswitches change to the open state. This arrangement stops the actuator at a pre-determined torque value regardless of the position in the mechanism stroke, the torque value being determined by the selection of the spring in the spring plunger.

[0072] A shoulder bolt 171 that is attached through the wrench jaws to the B1 housing and B1 cover defines the limit of travel of the wrench jaws in the closing direction.

[0073] Two mounting lugs 170 on the B1 housing 152 provide a means for mounting.

[0074] Compliance mechanism, 16 Any residual misalignment between the refueling tool wrench rotation axis and the FDV axis after clamping to the FDV body can induce side loads on the FDV as the wrench clamps to the FDV and also as the wrench rotates. To minimize side loads, a compliant mechanism provides a narrow range of spring center compliance in both the radial and tangential directions.

[0075] 9A, 9B, 10A, 10B, and 10C, a rectangular coupling platform 204 features a coaxial pair of protruding projections 205 along each of two parallel first edges of the platform's upper side, such that each projection is at the periphery of a corner of the platform. A similar arrangement of coaxial pairs of protruding projections 205 is similarly located on the underside of the platform along two edges perpendicular to the first edges, with the first edges oriented radially to the FDV's work field and the second edges oriented tangentially to the work field. Ball bushings 206 are attached to the protruding projections on either side of the platform, with the bushings secured to the protruding projections by bushing circlips 207 located at either end of the ball bushings, the circlips straddling the protruding projections.

[0076] A first pair of precision shafts 208 are supported in ball bushings on the upper side of the platform, one shaft per coaxial pair of bushings, such that at least 3 mm of the shaft extends beyond the outer ends of the coaxial pair of bushings. A coupling bracket 202 is attached to and straddles the first pair of precision shafts on the upper side of the platform via a pair of downsweep projections 203 symmetrically located on each of the two sides of the coupling bracket, the pair of downsweep projections spaced apart to receive an adjustable length locking shaft collar 210 therebetween, the shaft collars being used to center the coupling bracket on the precision shafts between the pair of ball bushings, adjustment of the adjustable length locking shaft collars being used to eliminate play between the coupling bracket and the first pair of precision shafts. A pair of compression springs 211 disposed on each of the first pair of precision shafts above the platform are disposed between the ball bushing 206 and the downsweep projection 203, each of which is partially compressed upon installation but allows limited spring-centered bilateral movement of the coupling bracket, shaft, and shaft collar relative to the coupling platform parallel to the axes of the first pair of precision shafts.

[0077] The second pair of precision shafts 209 are supported in ball bushings on the underside of the platform, one shaft per coaxial pair of bushings, such that at least 3 mm of the shaft extends beyond the outer ends of the coaxial pair of bushings. Mechanism B1 14 is attached to and straddles the second pair of precision shafts via B1 mounting lugs 170. The mounting lugs are fixed to each of the second pair of precision shafts via two length-adjustable locking shaft collars 210 per shaft, one on either side of each mounting lug, at the center of the shaft; adjustment of the length-adjustable locking shaft collars is used to eliminate play between mechanism B1 and the second pair of precision shafts. A pair of compression springs 211 disposed on each of the second pair of precision shafts beneath the platform are disposed between the ball bushings 206 and the adjustable length locking shaft collars 210, each of which is partially compressed upon installation but allows limited spring center bilateral movement of the mechanism B1, shafts and shaft collars relative to the coupling platform parallel to the axis of the second pair of precision shafts. The torque cell 201 is mounted between the coupling bracket 202 and the torque cell plate 200, which includes a mounting interface 212 for the compliance mechanism to mechanism B2.

[0078] Mechanism B2, wrench rotation, 18 Mechanism B2 is a wrench rotation device designed to rotate the wrench opening / closing mechanism B1 through a 70 degree hard stop limit arc in either a clockwise or counterclockwise direction, thus accomplishing one full rotation of the hexagonal mechanism in six incremental steps by repeatedly opening and closing the B1 mechanism for 60 degrees of back and forth rotation. The extra 10 degrees are a buffer between the commanded motion and the end of travel. The incremental rotation allows the mechanism to occupy primarily one side of the volume surrounding the FDV axis, thus allowing a clear view of the overall operation via a camera located on the opposite side of the volume.

[0079] 11A-11B, 12A-12D, and 13A-13B, a segment gear assembly 256 comprising a segment gear 257, an end of travel pin 260, a segment gear carrier 258, a first pair of track rollers 259, and a tensioner assembly 261 which itself comprises a second pair of track rollers 263, a tensioner yoke 262, a tension screw 264, and a disc spring 265 is constrained to rotate about a wrench rotation axis 270 via contact and preload between precision rolled surfaces 268 of a rotating track plate 250 and the first and second pairs of track rollers, the former contacting the outer precision rolled surfaces and the latter contacting the inner precision rolled surfaces, the precision rolled surfaces being sufficiently arc-shaped to permit ±35 degree rotation of the segment gear assembly about a central position, with the rim thickening formed by the precision rolled surfaces exceeding the arc-forming travel stop, and the wrench rotation axis being defined by the precision rolled surfaces.

[0080] Mechanism B2 drive housing 253 supports lead nut 155 and nut clamp 156, which is locked against rotation within the B2 drive housing and nut clamp by locking pin 157. B2 drive gear 251 with internally splined hub 252 is supported via bearings 254 housed in the B2 drive housing and rotating track plate. The segment gear assembly is constrained along the wrench rotation axis by segment gear bumpers 269 and thrust pads 255, the former attached to the rotating track plate and the latter attached to the B2 drive housing.

[0081] A pair of microswitches 266 separated by microswitch spacers 267 are mounted in a stacked configuration through slots in the rotating track plate near each end of the range of motion of end-of-travel pins mounted in the segment gears which allow adjustment of the stacked pair of microswitches so that they change from a free state to an actuated state to signal the end of rotation prior to the travel limiting thickening of the rim formed by the precision rolled surface. An elevation travel indicator 271 is mounted on the rotating track plate.

[0082] Mechanism C, wrench up, 20 Mechanism C is an elevation stage of wrench rotation mechanism B2 and requires the presence of mechanism B2 in order to function as a mechanism, therefore Figure 14A depicts only a portion of mechanism C, while Figure 14B, from the same perspective, includes mechanism B2 for clarity purposes.

[0083] With reference to these figures, and from another perspective to FIG. 15, a back plate 300 and an intermediate plate 301, which include the interface to mechanism A 129, are fixed together and form the basis of the RT structural frame. A pair of linear bearing rails 303 are fixed to the inward facing side of the back plate, oriented vertically and widely spaced above the back plate. A pair of linear bearing blocks 304 are precisely guided on each linear bearing rail. Right angle brackets 305 are attached to the linear bearing blocks, one per block, and arranged like bookends so that each pair of brackets straddles and supports the rotating track plate 250 of mechanism B 218. A pair of non-metallic bumpers 306 attached to the back plate at each end of each linear bearing rail define the limits of travel.

[0084] A pair of retract microswitches 307 are mounted through slots in the back plate near the top end of travel of the elevation travel indicator 271 of mechanism B 218, the slots allowing adjustment of the retract microswitches to change from a free state to an actuated state prior to contacting the non-metallic bumper, signaling the end of upward movement of mechanism C. A pair of extension microswitches 311 are similarly mounted through slots in the back plate near the bottom end of travel of the elevation travel indicator 271, the slots allowing adjustment of the extension microswitches to similarly signal the end of downward movement of mechanism C prior to contacting the non-metallic bumper. It will be appreciated that the present system and tool employ sensing means that are microswitches, although it will be understood that other types of sensors may be used, non-limiting examples include potentiometers.

[0085] A bearing 308 mounted within intermediate plate 301 supports mechanism B2 splined shaft 309 and mechanism C lead screw 310, which aligns and interfaces with the internally splined hub 252 of B2 drive gear 251, and thus the lead screw aligns and interfaces with the lead nut 155 of mechanism B2 18 to transfer torque to the B2 drive gear and drive mechanism C through its range of motion, regardless of the position of mechanism C.

[0086] Mechanism D, FDV connection, 22 Mechanism D22 is used to connect the refueling system to the FDV nipple 70 via the attachment of a safety valve 350. The safety valve 350 is a non-latching quick-connect device with a secondary check valve, designed to be permanently attached to the FDV in place of the B-nut after the B-nut has been removed. Once attached, it functions as a safe fluid coupling to pass fuel or oxidizer through the FDV to the client spacecraft, and provides two independent seals against leakage past the seat of the FDV's actuation nut, which is itself the primary seal of the line. With reference to Figures 16A and 16B, the safety valve 350 comprises a valve body 351 with an external capture groove 352, a coupling nut 353, and a spring 354, which features a completely independent check valve 356 and a quick-connect nipple 355, which is essentially another check valve that is forced open either by the action of the coupling or by applying pressure via the gas or liquid flowing after the coupling.

[0087] The quick connect couplings and nipples are non-latching. Specifically, unlike the vast majority of quick connect systems in common use, known as latching quick connects, which latch together via detent ball and groove interaction, and the locking action is released by axial movement of a spring-loaded external locking collar, non-latching quick connect couplings and nipples require an externally applied force to maintain connection between the coupling and nipple. Other embodiments may employ a latching quick connect coupling design, but when used with a refueling tool as presented herein, the latching function is redundant.

[0088] The safety valve 355 is designed to be installed on the FDV after the B nut is removed and before fuel or oxidizer is passed. Once fuel or oxidizer has been transferred through the safety valve 355, the safety valve 355 is left on the client valve. The quick connect coupling of the safety valve 355 allows subsequent refueling operations of the client satellite 81 at a later time to be performed faster and safer, with the added advantage that the refueling operation does not require the removal or reinstallation of the B nut or the actuation of the valve actuation nut to open or close, and overboard leakage of the valve actuation nut has been mitigated through the check valve and quick disconnect coupling.

[0089] As shown in Figures 17 to 20, mechanism D22 features two independent coaxial actuations of two carriages, hereafter referred to as D1 actuation and D2 actuation. Mechanism D2 actuation is dedicated to capturing and holding the safety valve, and then the ability to couple and decouple the robot arm's propellant delivery system to the safety valve via actuation of the quick connect coupling 385 to force the coupling and nipple together. Mechanism D1 actuation is dedicated to capturing and manipulating the safety valve along the FDV axis to remove it from storage and attach it to the FDV, the height of the FDV depending on the type of FDV being accessed. D2 actuation results in movement between the coupling / decoupling carriage assembly 380 and the safety valve carriage assembly 367. Actuation of mechanism D1 results in motion between the safety valve carriage assembly and mechanism D base plate 360, which carries all of the components of D2 actuation, and actuation of D1 and D2 is along the FDV axis in both a first direction and a second direction, the first direction being toward the FDV and the second direction being opposite to the first direction.

[0090] This embodiment uses a separate actuator for D2 actuation. Optionally, D2 actuation can be performed by an additional mechanism within the transmission 26.

[0091] 19 and 20, a first set of linear guide rails 362 are mounted to a Mechanism D base plate 360 ​​along with four adjustable end stops 363 and two dual microswitch assemblies 364 which operate to limit the commanded movement of the safety valve carriage assembly. Each dual microswitch assembly includes a forward microswitch 417 and a reverse microswitch 418.

[0092] The safety valve carriage assembly includes a safety valve carriage 368 having two locking arm posts 370 along the edges of the safety valve carriage closest to the FDV and symmetrically spaced about the FDV axis, the posts form a short stroke center of rotation for two symmetrical safety valve locking arms 372 which are mounted in flanged bushings 371, the distal ends of the locking arms are shaped to collectively form a compatible diameter with the external capture grooves of the safety valve body, and the locking arms each include a precisely shaped actuation slot 373 on the side adjacent the coupling / separation carriage assembly. A linear guide block 369, safety valve sensor assembly 374, compliant coupling assembly 375, first actuation actuator 376, microswitch striker 377, and a second set of linear guide rails 378 are all mounted to the safety valve carriage, the linear guide blocks maintaining precise alignment to the mechanism D base plate via the first set of linear guides.

[0093] The coupling / separation carriage 381 forms a platform for the coupling / separation carriage assembly and includes two track rollers 383 spaced symmetrically about the FDV axis along the edge closest to the FDV, the track rollers reside in actuation slots of the locking arms such that relative motion in a first direction between the coupling / separation carriage assembly and the safety valve carriage assembly causes the locking arms to swing towards each other and precisely fit within the external locking grooves of the safety valve, the precision slots being shaped to initially produce a rapid closing movement to a closed position and then maintain the locking arms in the closed position while allowing continued motion of the coupling / separation carriage assembly, with continued motion optionally being performed only when attempting to fully couple the quick connect coupling and nipple.

[0094] Also mounted on the coupling / separation carriage are a linear guide block 382, ​​a lead nut 384, a quick connect coupling 385, a manifold 386 with travel stops 388, and a dual microswitch assembly 387, the linear guide block ensures precise alignment between the coupling / separation carriage assembly and the safety valve carriage assembly via a second set of linear guides, the lead nut completes the connection to the mechanism D2 actuator, and the dual microswitch assembly interacts with the microswitch striker to signal the end of travel in the first direction.

[0095] Relative movement of the coupling / disengaging carriage assembly in a second direction relative to the safety valve carriage assembly correspondingly disengages the quick connect coupling and nipple when coupled, and thereafter fully releases the safety valve.

[0096] The locking arm actuation slot is shaped such that commanded motion of the coupling / separation carriage relative to the safety valve carriage can be completed only when the shaped end of the locking arm coincides with the safety valve's external locking groove, which is shaped with sufficient lead-in to aid alignment. Excessive misalignment will cause the locking arm to close around the safety valve's outer diameter instead of the external locking groove, stalling the D2 actuation and preventing the coupling / separation carriage from completing its commanded motion, which is aborted by current limiting of the D2 actuation.

[0097] To further aid in alignment of the locking arm with the safety valve's external locking groove, D2 actuation is triggered by a safety valve sensor assembly 374 comprising a sensor housing 405 and sensor base 406, both of self-lubricating material, a trigger plate 407, prime and redundant latch ready microswitches 408, a compression spring 409, and a limit pin 410, the compression spring being selected to be mounted with a preload and final load selected taking into account the robot arm's performance, force moment sensing capabilities and / or technology (if any), and FDV load limitations, the limit pin acting within a slot in the housing, the slot being equal in length to the microswitch stroke. The microswitch contacting one side of the trigger plate changes state when contact between the other side of the trigger plate and the top surface of the safety valve results in sufficient movement of the trigger plate for indication.

[0098] A flexible hose 365 is also shown in FIG. 19 and feature D on the opposite side of base plate 360 ​​and includes a right angle fitting which passes through a slot in the base plate to form a connection with manifold 386 .

[0099] D1 actuation between Mechanism D Base Plate 380 and Safety Valve Carriage Assembly 367 is accomplished via rotation of a splined input shaft 390 which drives a safety valve lead screw 394 via gears 392 and bearings 393 housed within a drive bracket 391, which is fixedly attached to the Mechanism D Base Plate. Rotation of the lead screw induces linear motion of a lead nut 395 contained within a guide housing 396, housing support guide pins 397, and connecting pins 398, which form a connection to the compliant coupling assembly 375. The guide pins and connecting pins allow for limited bilateral spring centered compliance between the safety valve carriage and the D1 actuation, the compliance being provided by the action of a shuttle 402 and spring 403 contained within a compliant housing 400 and compliant base 401, both made of a self-lubricating material.

[0100] A compliance microswitch 415 mounted to the guide housing and interacting with a compliance striker 416 attached to the safety valve carriage changes state when movement of the safety valve carriage assembly in a first direction is resisted by contact between the safety valve and the FDV, the change in state signalling the end of forward movement. In this way, the compliance microswitch effectively functions as a touch sensor indicating the safety valve is ready for installation.

[0101] Transmission, 26 The transmission 26 is used to selectively direct the first end effector tool drive input to one of four drive outputs 456, each of which is a rotating gear having an internally splined hub 457 that is compatible in size and relative position with the splined input shafts of mechanisms A, B2, C, and D.

[0102] 21, a transmission housing 450, top cover 451, and bottom cover 452 surround and support transmission gears 453 arranged in four separate layers, each layer designed to transmit torque from an input gear 454 to an output gear 456, with the input gears in each layer arranged on a common shaft 455. Each input gear features an internally splined hub 457 and is supported in bearings 458 in a support housing 459. Input gears and thrust washers 460, each with its own bearing and support housing, are included in the top and bottom covers, arranged in a stack within the transmission housing, such that one of the thrust washers is between the lower gear and the bottom cover in the stack, one of the thrust washers is between each successive gear and its support housing below, and one of the thrust washers is between the support housing of the upper gear and the top cover. The remaining gears, including the output gear, are mounted across two bearings 458, one in the transmission housing and one in one of the top and bottom covers.

[0103] The transmission is movably mounted via a mounting bracket interface 467. A lead nut 468 and nut clamp 469 attached to the transmission housing form the interface through which the transmission operates.

[0104] FIG. 22 includes a cross-sectional view of the stack of input gears, bearings, and support housings, each support housing having the form of a disk with a central hole, a full rim 461 on the inner diameter, and a partial rim 462 on the outer diameter that is an arc of approximately 300 degrees, the full inner rim forming a hollow shaft for the bearing, the partial outer rim forming a cover over the gear teeth of the input gear, except for a missing segment, and the missing segment of the outer rim of the support housing allowing the input gear to mesh with other gears. As can be seen in FIG. 21, the outer diameter of the partial outer rim of the support housing is interrupted by three cylindrical grooves 463. A bore 464 in the transmission housing that precisely positions the support housing through its outer diameter is also parallel to the axis of the transmission housing bore and is interrupted by holes 465 punched through the cylindrical wall of the bore, so that the axis of each groove on the outer diameter of the support housing can be aligned with the axis of the hole in the transmission housing by rotating the support housing in the transmission housing bore. The locating pins 466 that fit into the holes in the transmission housing form a locating feature along the entire length of the bore such that the support housing can only be installed in one of three rotational orientations, each of the three orientations being determined by one of the three cylindrical grooves, thus allowing the outer rim opening of the support housing of the input gear to maintain alignment with the next gear of each layer. In the current embodiment, three grooves are sufficient for four layers of gearing only because two non-adjacent layers share a similar output orientation. In another embodiment, one groove may be required for each layer of gearing. Additionally, the only reason to include all the grooves on all the support housings is one of compatibility. Alternatively, each support housing can be made for a particular layer with a single groove that is correspondingly located.

[0105] Each of Figures 23A through 23D shows a cross-section of the transmission through one of four layers of gearing, each layer including one of the input gears, one or two idler gears, and one of the output gears.

[0106] 24 is a cross-sectional view directly underneath the refueling tool top plate 479 showing the transmission 26 mounted to two linear guide rails 471 via linear guide blocks 472 and a transmission bracket 470. The linear guide rails are attached to a transmission support plate 473, which is located and supported between the top plate 479 and the middle plate 301 with bolt and pin connections.

[0107] 24 also shows linear potentiometer 476, potentiometer bracket 477, and potentiometer rod bracket 476. The body of the linear potentiometer, which is attached to refueling tool mid plate 301 via the potentiometer bracket, remains stationary while the potentiometer rod bracket, which is attached to transmission 26, moves with the transmission and therefore reports the position of the transmission within its range of motion.

[0108] 25 is a top view of refueling tool 10 showing elements of refueling tool end effector interface 500: gripping fixture 501, first rotary drive input 502, second rotary drive input 503, electrical connector 504, and quick connect nipple 505. The quick connect nipple is attached to fuel channel 513, which provides a sealed delivery passage to flexible hose 365 of mechanism D22. The cutaway view of FIG. 25 reveals that first rotary drive input gear 507 transmits the first rotary drive input to quill shaft 509 via transmission gear 508 and quill shaft drive gear 514, which are supported and enclosed within transmission housing 515.

[0109] FIG. 26 is a cross-sectional view of the stack of quill shaft 509, quill shaft drive gear 514, and transmission input gear 454. The quill shaft is positioned and supported at its lower end by bearing 510 and bearing retainer 511 in middle plate 301. The upper end of the quill shaft is supported by quill shaft external splines 512 that engage corresponding internal splines of quill shaft drive gear 514. A second set of external splines 512, approximately midway along the length of the quill shaft, are sized and positioned to engage the lowest transmission input gear 454 in the stack when the transmission is at the top end of the transmission range of motion 485, the range of motion being sufficient to allow the second external splines to engage each of the four transmission input gears. The cutaway view of FIG. 26 reveals the transmission lead screw 484 of the second rotational input 503 and the lead nut 474 attached to the transmission such that the second rotational input can be used to drive the transmission on linear guides throughout the range of motion.

[0110] FIG. 27 conceptually illustrates dexterous dexterous end effector 550 having the components required for a refueling operation, namely, gripping mechanism 551, first rotary drive socket 552, second rotary drive socket 553, robotic control matable power and data signal connector driving electrical connector 554, movable quick connect propellant coupling 555, and camera 556. Propellant coupling 555 is connected upstream to propellant transfer system 960 via a hose. Camera 556 provides a close-up view of gripping fixture 501 on refueling tool 10 prior to gripping by end effector 550, and similarly, grapple fixture 610 prior to gripping by end effector 550 of either a refueling support tool (608, 609) or a site preparation tool (605, 606, 607). In one embodiment of the refueling system, fiducial marks or machine vision targets (not shown) are placed adjacent to gripping fixture 501 on top plate 479. This allows the processor 830 of the computer control system 800 to calculate the position of the gripping fixture 610 based on the video stream image of the target obtained from the camera 556. This position can be used to guide the movement of the robotic arm 84 by the automated control system 830 to the grab-ready position of the grapple or gripping fixture. Alternatively, a video representation of the fiducial mark can be displayed to a human remote operator to guide the movement of the robotic arm 84 to the grab-ready position. The refueling support tools (608, 609) and site preparation tools (605, 606, 607) can be similarly equipped with fiducial marks or targets on the common tool base structure 620 adjacent to the grapple fixture 610. These cameras 556 can also be used to monitor the operation of the tool tips of the blanket cutter tool 605, blanket handling tool 606, wire cutter tool 607, B nut removal tool 608, and crush seal removal tool 609.

[0111] During operation, after servicer spacecraft 80 captures client satellite 81 on tether 950, and after FDV work site 50 has been prepared using robotic arm 84 and support tools in a series of operations to expose FDV 54, robotic arm 84 then moves refueling tool 10 to FDV work site 50, aligns it with a selected FDV 54 axis, and then approaches along the FDV axis to effectively lower refueling tool 10 onto FDV bracket 52. Refueling tool vision system 40 of refueling tool 10 provides the primary means for sensing correct alignment of refueling tool 10 to FDV 54 and monitoring the approach to FDV bracket 52 until contact between touchdown sensing system contact sphere 490 and FDV bracket 52 is sensed by force / moment sensing or other means within the robotic arm 84 or tool.

[0112] Thereafter, actuation of mechanism A12 causes mechanism A12 to close symmetrically about valve body 56 and torque reaction plane 58, bringing refueling tool 10 and FDV 54 into final alignment, thereby clamping valve body 56 and torque reaction plane 58. The operator, primarily using the view from camera 42, first verifies through the view from camera 42 that mechanism B114 is open enough to open and close the wrench, and then uses mechanism C20 to lower wrench jaws 154 to a position near the mid-height of actuation nut 62. Mechanism B218 for wrench rotation is then adjusted so that wrench jaws 154 are parallel to the pair of planes of actuation nut 62 that are closest to the mid-height of the wrench rotation range. Mechanism B114 is then commanded in the closing direction. Once wrench jaws 154 are closed, the operator may pause to further adjust wrench rotation or wrench height into a more precise alignment, using mechanisms B218 and C20, respectively.

[0113] Once the view from camera 42 is satisfied that the alignment between wrench jaws 154 and actuation nut 62 is good, the operator commands wrench jaws 154 to fully close, where the closing action automatically stops when mechanism B 114 reaches a preset level of torque determined by preload microswitch 169 of mechanism B 114. Once actuation nut 62 is within wrench jaws 154, the operator commands a clockwise rotation at a preset level of torque to ensure the actuation nut is closed. These actions ensure that actuation nut 62 is fully closed and ready for refueling before any subsequent operations on FDV 54. After the preset level of torque has been applied, whether or not actuation nut 62 has been rotated, the actuation nut is released and wrench jaws 154 are reconfigured into an alignment similar to B nut 64 on the top of FDV 54 using mechanisms B 114, B 218, and C 20 for wrench open / close, wrench turn, and wrench lift, respectively. After aligning and closing with the B nut 54, using the same methodology as described for the actuation nut 62, the mechanism B 218 is actuated in a counterclockwise direction. Unlike the actuation nut 62, the B nut 64 must be rotated to successfully complete this step. Approximately a quarter turn is required to ensure that the refueling tool 10 has fully loosened the B nut 64, which is accomplished by repeatedly closing, then rotating CCW, then opening, then rotating CW of the wrench jaws 154.

[0114] The refueling tool 10 is then stowed aboard the servicing spacecraft 80 for removal of the B nut 64 and the crush seal 702 from the FDV 54 using the B nut removal tool 608 and the crush seal removal tool 609, respectively. After the B nut 64 and the crush seal 702 have been safely removed and discarded aboard the servicing spacecraft 80 using the B nut removal tool 608 and the crush seal removal tool 609, the robotic arm 84 again retrieves the refueling tool 10 from its stowage location on the servicing spacecraft 80 and uses it to retrieve the safety valve 350, also from its stowage location on the servicing spacecraft 80. Using the same approach methodology at the safety valve stowage location, and also using mechanism A12 to close the perimeter of the base of the safety valve stowage location, the safety valve carriage assembly 367 of mechanism D22 is commanded forward until the trigger plate 407 contacts the safety valve shoulder 357, actuating the latch ready microswitch 408.

[0115] The mating / disconnecting carriage assembly 380 then moves forward causing the locking arms 372 to close around the safety valve assembly 350 and lock into the external locking grooves 352 of the safety valve assembly 350, with confirmation of the closing action coming from the view of the camera 42. The mating / disconnecting carriage assembly 380 further moves forward to fully mating the quick connect 355 of the safety valve assembly 350 with the quick connect coupling 385 of the refueling tool 10, as confirmed by the dual microswitch assembly 387.

[0116] Thereafter, using mechanism B114, mechanism B218, and mechanism C20, the wrench jaws 154 are aligned with the flats of the coupling nut 353 of the safety valve assembly 350, closed on the coupling nut 353, and loosened and rotated the coupling nut 353 a predetermined number of revolutions to release the safety valve assembly 350 from the storage location, where the loosening of the coupling nut 353 is coordinated by the axial movement of the coupling nut 353 provided by the spring 354 of the safety valve assembly 350. The safety valve assembly 350 is then fully retracted into mechanism D22 by retracting the safety valve carriage assembly 367, confirmed by the retraction microswitch 418 of the safety valve carriage assembly 367. After the safety valve assembly 350 is returned to the FDV work site 50, realigned, and re-clamped to the FDV valve body 56 and torque reaction plane 58, the safety valve carriage assembly 367 with the safety valve assembly 350 is commanded toward the FDV 54 until the coupling nut 353 contacts the FDV 54, which is evident in the camera view by the compression of the safety valve spring 354, as well as indicated by the compliance microswitch 415 of mechanism D22.

[0117] Mechanism B114, mechanism B218, and mechanism C20 are then used to manipulate wrench jaws 154 into position on coupling nut 353, close on coupling nut 353, and repeatedly rotate coupling nut 353 in a CW direction while monitoring the view from camera 42 for progress. The same spring resistive action that actuated compliance microswitch 415 to indicate contact between safety valve coupling nut 353 and FDV nipple 70 allows there to always be a small force acting to push the threads of coupling nut 353 and FDV nipple together.

[0118] Once safety valve assembly 350 is attached to FDV 54, mechanism B114, mechanism B218, and mechanism C20 are then used to align wrench jaw 154 with actuation nut 62 and loosen and rotate actuation nut 62 a predetermined number of turns to fully open actuation nut 62 for subsequent fluid transfer. Once fluid transfer is completed from servicer spacecraft 80, through refueling tool 10, through check valve 356 of safety valve assembly 350, to FDV 54, and thus to client spacecraft 81, the operator then verifies that wrench jaw 154 is aligned with actuation nut 62, and, if necessary, then aligns wrench jaw 154 with actuation nut 62 using mechanism B114, mechanism B218, and mechanism C20. Wrench jaw 154 is then commanded to rotate actuation nut 62 a predetermined number of turns to fully close actuation nut 62 after completion of fluid transfer. The coupling / discoupling carriage assembly 380 is then retracted until the quick connect 355 of the safety valve assembly 350 is disengaged from the quick connect coupling 385 of the refueling tool 10 as confirmed by the dual microswitch assembly 387 .

[0119] Mating / separating carriage assembly 380 is then further retracted to fully release locking arm 372 from outer locking groove 352 of safety valve assembly 350 while the opening action is viewed from camera 42. Safety valve assembly 350 is left on client spacecraft 81 after refueling is completed, and refueling tool 10 is subsequently mated to safety valve fixture 83 on servicer spacecraft 80 to purge propellant hose 980 and refueling tool 10 through safety valve fixture 83 prior to stowing refueling tool 10 aboard servicer spacecraft 80.

[0120] Support Tools 28-36, refueling support tools 601 are independent tools used for specific steps of the refueling flow. Each of these tools 601 has a common tool base structure 603 and a specific tool tip designed for the specific task for which the tool is required. The common tool base 603 allows for a single robotic interface to a manipulator system with a specific "end of arm assembly" while allowing for the accomplishment of several tasks. The common base structure 603 is composed of a grapple fixture 610, which is a gripping interface for tools designed for robotic gripping by the "end of arm assembly" located at the end effector 550 of the robot arm 84 attached to the servicer spacecraft 80 (see FIG. 54). The base structure 603 further includes tool mechanism drive interfaces 612 and 613, which are used to perform any tool function via a drive actuator mechanism located on the "end of arm assembly." In the embodiment described herein, there are two tool mechanism drive inputs, one of which is used to drive a specific tool tip of each support tool, and the second is to drive a "constraint" mechanism to hold the tool when not grasped by the manipulator system. The base 603 includes a tool mechanism gear train 614 to transmit rotation and torque from one of the tool mechanism drive input interfaces through a tool mechanism gear train interface 632 to a tool tip drive shaft 634 to actuate that tip. The base 603 includes a constraint mechanism "active half" 618 that is driven by a second tool mechanism drive 613 interface, either directly, or in an alternative embodiment, through another gear train transmission to an alternative constraint mechanism location. The base 603 includes a structure 620 that holds the common base 603 components together.

[0121] The common tool base 603 has an interface to a tool tip 630 that is permanently attached to the common base tool 603 instance at a tool tip to tool base gear train interface 632 and a tool tip bolted interface 638. This interface includes mechanisms that allow for the transfer of rotary mechanical power from the tool mechanism gear train interface 632 to the tool tip drive shaft 634. The tool tip main structure 636 is fixedly connected to the common tool base 603 in this embodiment by using the bolted interface 638.

[0122] The refueling operation has several functions assigned to the support tools. These include site preparation tools including a blanket cutter tool 605, a blanket handling tool 606, and a wire cutter tool 607. The tool tips 630 of all three site preparation tools are similarly designed such that they all require a simple scissor action linkage to perform their functions. The refueling support tools include a B-nut removal tool 608 and a crush seal removal tool 609. Each of these is described below.

[0123] Site Preparation Tool 37-39, in each of the site preparation tool tips, blanket cutter 650, blanket handler 652, and wire cutter 654, a tool tip drive shaft 634 is internally threaded and has a forward threaded rod 640 attached to it. Rotation of the drive shaft 634 causes linear motion of the forward threaded rod 640, which in turn moves a set of short input linkages 642, which in turn cause an output linkage 644 to pivot about a particular point on any tool tip, causing the motion mechanisms of the device to open or close, depending on the direction of motion. These motion mechanisms are the cutting shears 645 of the blanket cutter 650, the tweezer grip paddles 646 of the blanket handler 652, and the gripping mechanism 647 of the wire cutter 654.

[0124] B Nut removal tool tip 40-45, the B nut removal tool tip 660 has two stages of motion. First, the collet 662 is driven forward by the rotation of the drive shaft 664 caused by the cam pin 666 running within the slot 668 of the collet 662 until the spring wrench fingers 670 contact the B nut hex 672 and / or the cam pin 666 reaches the end of the collet slot 668. The drive shaft 664 then continues to rotate, forcing the ratchet disk 674 interface apart and rotating the pin carrier housing 676 with the collet 662 and spring fingers 670, so that the B nut 64, captured by the shape of the closed spring fingers 670, is unscrewed from the FDV 54. To discard the B nut 64, the drive shaft 664 is rotated in the opposite direction to that described above. The ratchet disc 678 limits movement of the pin carrier 676 in this direction, forcing the collet 662 back and allowing the wrench spring fingers 670 to open, thus releasing the B nut 64 .

[0125] The ratchet disk 678 controls the rotational movement of the pin carrier housing 676 by being keyed 682 for rotation relative to the tool tip base structure 680 while being preloaded against the pin carrier housing 676 by a preload spring 684. The ratchet disk surface 686 and the binding surface 688 of the pin carrier housing 676 have a binding ramp mechanism. Movement is possible in one direction where the shallow angle surfaces of the ramps slide against each other only if the input torque is sufficient to slide the ramps against each other while under the preload of the preload screw 684 which presses the ratchet disk 678 against the pin carrier housing 676, which is the rotation of the tool to remove the B nut 64. In the other direction, the steeper sides of the ramps engage and relative movement in that direction is restrained, allowing the collet 662 to move and release the B nut 64. The reaction force of the ratchet disc interface 674 allows axial motion of the collet 662 to occur before rotational motion.

[0126] Crush Seal Removal Tool 46-50, the crash seal 702 may be glued to the FDV valve shaft 716 and must be removed before installing a safety valve 350 with a new crash seal 702. To operate the crash seal removal tool tip 700, the drive shaft 704 is rotated, which translates the plunger 706 rearwardly into the drive shaft 704. The drive shaft 704 has female threads while the plunger 706 has male threads where they interface 708. As the plunger 706 translates, the pivot point 710 of the flex jaw linkage 712 moves with the plunger 706, closing and retracting the flex jaw tip 714 into contact with and retracting along the FDV valve shaft 716. The flex jaw tip 714 is preloaded against the FDV valve shaft 716 and is retracted together until they catch on the crash seal 702 and the crash seal 702 is forced loose. When the flex jaw tip 714 is freed from the FDV valve shaft 716, the crush seal 702 is held within a cage 718 which is connected to a tool tip base structure 719 which in turn is connected to the common base 603. Rotating the drive shaft 704 in the reverse direction opens the flex jaw tip 714 and pushes the crush seal 702 out of the tool tip 700, but pushes the plunger face 720 forward, forcing the crush seal 702 out of the cage 718.

[0127] Tool constraints 51-53, an embodiment of a tool restraint method is to use a ball-lock, quick-disconnect mechanism. This is a restraint that uses input mechanical motion from the end effector to allow for restraint and retention on the spacecraft without the need to have an active mechanism for each tool restraint. If an active restraint mechanism is not feasible for all tools on the servicer deck, this tool restraint method eliminates the need for a second robotic arm to provide actuation to restrain the support tool while it is being held by the first robotic arm 84. In this mechanism, once the robotic arm positions the tool such that the restraint of the tool 730 is fully engaged within the locking interface of the spacecraft 732, the second tool mechanism drive 613 rotates on the tool, guided by appropriate visual cues 734 and arm control software of the tool and servicing spacecraft. This rotation is transferred by actuator splines in the restraint 740 to splines 736 on the lead screw drive shaft 738 in the spacecraft receptacle 732. Rotation of the drive shaft 738 advances the ball-lock sleeve 742, forcing the balls 744 in the spacecraft receptacle 732 into the notches 746 in the constraint 748, thus retaining the constraint 748 and attached tool constraint half 730 in the spacecraft receptacle 732. A visual cue indicator 752 is provided to provide visual confirmation of tool constraint. As the ball-lock sleeve 742 advances, a protrusion on the ball-lock sleeve 750 simultaneously presses against a spring-loaded indicator 752 in the tool, thus exposing more and more of the spring-loaded indicator 752 as the ball-lock sleeve 742 advances. The spring-loaded indicator 752 is clearly marked so that a visual indication is clearly visible when the ball-lock sleeve 742 is fully engaged with the constraint 748. Release of the constraint is accomplished through rotation of the second torque drive 613 in the opposite direction. Alternative embodiments of the constraint are possible, including a breech-lock type.

[0128] Details of working with the Refueling Tool (RT) Figure 54 shows a servicer spacecraft 80 and a client satellite 81 being refueled by the servicer spacecraft 80. Figure 55 shows a non-limiting illustrative example of a computer control system that may be used to control the operation of the refueling tool 10.

[0129] The tool 10 disclosed herein for accessing a fill / drain valve 54 on a client satellite 81 may be mounted on a dedicated refueling or servicer spacecraft 80 launched directly from Earth.

[0130] The system also includes a propellant transfer system 960 for transferring bipropellant or monopropellant from the servicing satellite 80 to the client satellite 81 as described in U.S. Patent No. 8,899,527, issued December 2, 2014 (herein incorporated by reference in its entirety), the purpose of which is to provide a propellant transfer system 960 (FIG. 54) for transferring propellant under a combination of remote operator and computer control. Such a dedicated servicer spacecraft 80 may include a spacecraft docking mechanism as described in U.S. Patent No. 6,969,030, issued November 29, 2005 (herein incorporated by reference in its entirety).

[0131] FIG. 54 shows items associated with refueling a client satellite 81 in addition to the refueling tool 10. These include the servicer spacecraft 80, as well as the client fill / drain valve 54, the robotic arm 84, the end effector 550 connected to the robotic arm 84, the refueling tool 10 releasably graspable by the end effector 550, the propellant transfer system 960, the movable quick connect propellant coupling 555 attached to the end effector 550, the propellant outlet hose 980 extending along the arm 84, and the communications system 930 providing a two-way radio link 934 to Earth 940 (or to a space station or mother ship, whichever is the location of remote control). Stowage points are shown for the refueling tool 10, the safety valve fixture 83, the storage post 82 for the safety valve assembly 350, the blanket cutter tool 605, the blanket handling tool 606, the wire cutter tool 607, the B nut removal tool 608, and the crush seal removal tool 609.

[0132] FIG. 54 shows a tether 950 fixedly attached at its proximal end to the servicing spacecraft 80 and releasably attached at its distal end to the client spacecraft 81. In one embodiment, the tether 950 comprises a manipulator arm of equivalent function and performance to the robot arm 84 and end effector 550 having a grapple fixture 501 (not shown in FIG. 54) attached to the exterior of the client spacecraft 81, compatible with grasping by the tether 950. In a second embodiment, the tether comprises a spacecraft docking mechanism as disclosed in U.S. Pat. No. 6,969,030, the docking interface described in this patent being attached to the exterior of the client spacecraft. The tether must establish a sufficiently rigid, load-bearing structural connection between the servicing spacecraft 80 and the client satellite 81 prior to the start of the refueling operation described in FIGS. 56A and 56B. The robot arm 84 and end effector 550 and servicing tools must be sufficiently rigid so that interaction with surfaces or features of the client spacecraft 81 does not create loads that cause material changes in the relative position and orientation of the client spacecraft 81 with respect to the servicer spacecraft 80.

[0133] Additionally, the servicer spacecraft 80 includes an on-board computer control system 800 (FIG. 55) that may be interfaced with the tool 10 in addition to the propellant flow control system indicated at 862, to drive all components that are opened or closed during a propellant transfer operation in a selected sequence depending on which mode of propellant transfer is selected based on the pressure in the propellant tanks of the client satellite 81. Due to the presence of the computer control system 800 interfacing with the propellant flow control system, the propellant transfer process may be autonomously controlled by a local mission manager or may include some level of supervised autonomy such that in addition to being under pure teleoperation, there may be mixed teleoperation / supervised autonomy.

[0134] An exemplary computer system 800 forming part of the propellant replenishment system is shown (FIG. 55). The system includes a computer control system 825 configured and programmed to control the movement of the robotic arm 84, including the handling and manipulation of the servicing tools (10, 605, 606, 607, 608, and 609) and the safety valve assembly 350, through the servicing sequence of tasks shown in FIG. 56A and FIG. 56B.

[0135] Command and control system 800 is also configured to control the movement of robotic arm 84 and its attached end effector 550 to control the operation of refueling tool 10 and the support tools. This may be the same command and control system as described above interfaced with a flow control system, e.g., a computer attached to servicer spacecraft 80 that is programmed with instructions to perform all of the operations that need to be performed by servicer spacecraft 80 during approach, capture / docking, and refueling operations with client satellite 81, or it may be a separate computer system.

[0136] The satellite refueling system includes a refueling tool vision system 40 for viewing the operation of the refueling tool operations at the fill and discharge valves. It also includes a robot vision system 850 for the purpose of general robot state awareness and monitoring the operation of the tool tips of the blanket cutter tool 605, blanket handling tool 606, wire cutter tool 607, B-nut removal tool 608, and crush seal removal tool 609. It can also be used for work site alignment. In this last function, the robot vision system is used to determine the position of objects in the general work site relative to a command frame of reference on the end effector 550. This position is determined as the position and orientation of the object of interest relative to the frame of reference on the end effector 550. The object of interest includes the position of any of the refueling tool 10, refueling support tools (608, 609), and site preparation tools (605, 606, 607) in their stowed locations on the servicer spacecraft. Other objects of interest include the position of the FDV 54 on the client spacecraft 81.

[0137] Communications system 930 is interfaced with robotic arm 84 and configured to enable remote operation (from Earth 940 or other suitable location) of robotic vision system 850, refueling tool vision system 40, robotic arm 84, and thus, the refueling and support tools. The vision system may include separate markers attached to fluid transfer couplings used to connect the fluid transfer system storage tanks and piping system to the fill / drain valves of the client satellite 81, as well as markings on all tools associated with the fluid transfer operation.

[0138] These cameras may be used within a teleoperated robotic control mode, where an operator controlling maintenance operations on Earth sees a clear view of the work site on a display screen of a command and control console. In an alternative mode, the position of elements such as fill and discharge valves may be determined either by a stereo camera and vision system that extracts 3D points and determines the position and orientation of the fill and discharge valves or other relevant mechanisms of the work site from which the robot arm holding tools (multi-function tools, refueling tools) can be driven to these positions according to the sensed 6 degree of freedom coordinates.

[0139] The stereo camera may also be replaced by a scanning or flash lidar system from which the desired 6 degree of freedom coordinates can be obtained by acquiring a measured 3D point cloud and estimating the pose of the desired object based on a stored CAD model of the desired feature or shape of the refueling work site. For those applications designed to have spacecraft being serviced, simple targets such as those described by Ogilvie et al. (Ogilvie, A., Justin Allport, Michael Hanna, John Reimer, "Autonomous Satellite Servicing Using the Orbital Express Demonstration Manipulator System," Proceedings of the 9th International Symposium on Artificial Intelligence, Robotics, and Automation in Space (i-SAIRAS'08), Los Angeles, CA, February 25-29, 2008) may be used in combination with a monocular camera on the servicing robot to locate an item of interest such as a fill and discharge valve 54. Finally, the robot arm or device 84 used to position the device may include a sensor or sensors capable of measuring reaction forces between the tool and the work site (e.g., the fill and discharge valve 54). These can be displayed to the operator to assist him in remote control, or can be used in an automatic force moment regulation control mode, either to assist the remote operator, or in a supervised autonomous control mode.

[0140] As mentioned above, the computer control system 825 is interfaced with the robot vision system 850, the refueling tool vision system 40, the propellant transfer system flow control system 862, and the robot arm 84. There is provided a communication system 930 as previously described that is interfaced with the robot arm 84 and configured to enable remote operation (from Earth 408 or any other suitable location) of the robot vision system 850 (which may also include a camera 556 in the end effector 550), the refueling tool vision system 40, the robot arm 84, the robot end effector 550, the blanket cutter tool 605, the blanket handling tool 606, the wire cutter tool 607, the B nut removal tool 608, the crush seal removal tool 609, the refueling tool 10, and the flow control system 862 ( FIG. 55 ). This type of system is highly advantageous, particularly for space-based systems where remote control is required.

[0141] The end effector 550 has its own embedded processor (as does the robotic arm 84) and receives commands from the servicing spacecraft's computer. The end effector 550 also passes power and data from the central computer to the refueling tool 10. Since the refueling tool 10 does not have an embedded computer / microcontroller, actuator commands are received from the computer control system 825 upstream through the end effector 550. The end effector 550 embedded processor also receives video signals from the refueling tool camera 40 and telemetry from tool sensors including, but not limited to, linear potentiometer 476 and microswitches (127, 169, 266, 307, 311, 364, 387, 408, 415, 417, and 418). These sensed values ​​can be used in closed loop control system functions within the end effector. They are also passed to the command and control system 800 for overall on-orbit control and can also be displayed to a human remote operator on Earth or in another spacecraft.

[0142] Some aspects of the present disclosure may be embodied, at least in part, in software. That is, the present technology may be implemented in a computer system or other data processing system corresponding to its processor, such as a microprocessor, executing sequences of instructions contained in a memory, such as a ROM, a volatile RAM, a non-volatile memory, a cache, a magnetic and optical disk, or a remote storage device. Furthermore, the instructions may be downloaded to a computing device in a compiled and linked version format over a data network. Alternatively, the logic for performing the above processes may be implemented in a machine-readable medium, such as an additional computer and / or a separate hardware component, such as firmware, such as a large scale integrated circuit (LSI), an application specific integrated circuit (ASIC), or an electrically erasable programmable read-only memory (EEPROM).

[0143] As discussed above, FIG. 55 provides an exemplary, non-limiting implementation of a computer control system 825 forming part of a command and control system that includes one or more processors 830 (e.g., CPU / microprocessor), a bus 802, memory 835 which may include random access memory (RAM) and / or read-only memory (ROM), one or more internal storage devices 840 (e.g., a hard disk drive, compact disk drive, or internal flash memory), a power supply 845, one or more communication interfaces 813, and various input / output devices and / or interfaces 860.

[0144] Although only one of each component is shown in FIG. 55, any number of each component may be included in computer control system 825. For example, a computer typically includes different data storage media. Additionally, while bus 802 is shown as a single connection between all components, it will be understood that bus 802 may represent one or more circuits, devices, or communication channels linking two or more components. For example, in a personal computer, bus 802 often includes or is a motherboard.

[0145] In one embodiment, the computerized control system 800 may be or include a general-purpose computer or any other hardware equivalent configured to operate in space. The computerized control system 800 may also be implemented as one or more physical devices connected to the processor 530 through one of one or more communication channels or interfaces. For example, the computerized control system 800 may be implemented using an application specific integrated circuit (ASIC). Alternatively, the computerized control system 800 may be implemented as a combination of hardware and software, where the software is loaded into the processor from memory or over a network connection.

[0146] The computerized control system 800 may be programmed with a set of instructions that, when executed on a processor, cause the system to perform one or more of the methods described in this disclosure. The computerized control system 800 may include many more or fewer components than those shown.

[0147] While some embodiments have been described in the context of fully functional computers and computer systems, those skilled in the art will appreciate that various embodiments may be distributed as program products in a variety of forms and may be applicable regardless of the particular type of machine or computer readable medium used to actually effect the distribution.

[0148] Computer-readable media can be used to store software and data that, when executed by a data processing system, causes the system to perform various methods. The executable software and data can be stored in various locations, including, for example, ROM, volatile RAM, non-volatile memory, and / or cache. Portions of this software and / or data can be stored in any one of these storage devices. In general, machine-readable media includes any mechanism that provides (i.e., stores and / or transmits) information in a form accessible by a machine (e.g., a computer, a network device, a personal digital assistant, a manufacturing tool, any device having a set of one or more processors, etc.). Examples of computer-readable media include, but are not limited to, recordable and non-recordable types of media, such as volatile and non-volatile memory devices, read-only memory (ROM), random access memory (RAM), flash memory devices, floppies and other removable disks, magnetic disk storage media, optical storage media (e.g., compact disks (CDs)), digital versatile disks (DVDs), among others. The instructions may be embodied in digital and analog communication links for electrical, optical, acoustic or other forms of propagated signals, such as carrier waves, infrared signals, digital signals, and the like.

[0149] Current systems are also configured for fully autonomous operation. A fully autonomous system is one that measures and responds to its external environment, and full autonomy is often pursued for conditions that require highly responsive changes in system state to external conditions or conditions that require rapid decision making to control dangerous conditions. Implementing full autonomy is often costly and often cannot handle unexpected or highly uncertain environments. Supervised autonomy, where a human operator can initiate autonomous states within the system, offers the benefits of a responsive autonomous local controller with the flexibility provided by a human remote operator.

[0150] The block flow chart shown in Figures 56A and 56B details the steps taken by servicer spacecraft 80 when engaging a client satellite 81 during a refueling operation.

[0151] 4.3 Tightening / closing the actuation nut a. Touch down contact ball 490 on FDV bracket 52 and use the view from camera 42 to verify that both refueling tool 10 is lowered and that jaws 121, center and clamps 12 of Mechanism A are fully open. b. Select mechanism A, center and clamp 12 with transmission 26 and verify selection using linear potentiometer 477 readout. c. Clamp the FDV torque reaction plane 58 with mechanism A, center and clamp 12 and use the clamped microswitch 127 to verify that the clamp load is applied to the fill / drain valve, FDV 54. d. Select mechanism C, wrench up 20 in transmission 26 and verify selection using linear potentiometer 477 readout. e. Using the view from camera 42, adjust mechanism C, wrench lift 20 so that wrench jaw 154 is aligned with actuation nut 62. Monitor end of travel microswitch 307 during motion. f. Close wrench jaws 154 on actuation nut 62 using mechanism B1, close / open wrench 14 and verify condition using preload microswitch 169 while monitoring the view from camera 42. g. Select mechanism B2, wrench rotation 18 in transmission 26 and verify selection using linear potentiometer 477 readout. h. Mechanism B2, use wrench rotation 18 to rotate actuation nut 62. Monitor the view from camera 42 during rotation and the readout from CW / CCW microswitch 266 and torque cell 201 at the end of mechanism travel. i. Use mechanism B1, wrench close / open 14 to open wrench jaws 154 from actuation nut 62 and verify condition using preload microswitch 169 while monitoring the view from camera 42.

[0152] 4.4 Loosen the B nut seal of the FDV a. Select Mechanism C, Wrench Up 20 in the transmission 26 and verify selection using the linear potentiometer 477 readout. b. Using the view from camera 42, adjust mechanism C, wrench lift 20 so that wrench jaw 154 is aligned with B nut 64. Monitor end of travel microswitch 307 during motion. c. Close the wrench jaws 154 on the B nut 64 using mechanism B1, close / open wrench 14, and verify the condition using the preload microswitch 169 while monitoring the view from camera 42. d. Select mechanism B2, wrench rotation 18 in transmission 26 and verify selection using linear potentiometer 477 readout. e. Mechanism B2, rotate B nut 64 using wrench rotation 18. Monitor the view from camera 42 during rotation and the readout from CW / CCW microswitch 266 and torque cell 201 at the end of mechanism travel. f. Use mechanism B1, close / open wrench 14 to open wrench jaws 154 from actuation nut 62 and verify condition using preload microswitch 169 while monitoring the view from camera 42. g. Select Feature A, center and clamp 12 with transmission 26 and verify selection using linear potentiometer 477 readout. h. Unclamp mechanism A, center and clamp 12 from FDV torque reaction plane 58 and use clamped microswitch 127 to verify that the clamp load has been removed from the fill / drain valve, FDV 54.

[0153] 7.2 Capturing the Spacecraft (S / C) Safety Valve (SV) - Engaging the Quick Connect (QC) and Release the Fitting Nut a. Touch down contact sphere 490 on servicer spacecraft 80 and use the view from camera 42 to verify that refueling tool 10 is lowered and that jaws 121, center and clamps 12 of mechanism A are fully open. b. Select mechanism A, center and clamp 12 with transmission 26 and verify selection using linear potentiometer 477 readout. c. Mechanism A, center and clamp 12 clamp storage post 82 and use clamped microswitch 127 to verify that the clamp load is applied to storage post 82. d. Mechanism D, select FDV connection 22 at transmission 26 and verify selection using linear potentiometer 477 readout. e. Advance the safety valve carriage assembly 367 until the trigger plate 407 contacts the shoulder 357 of the safety valve body 351, as confirmed by the latch ready microswitch 408. f. Begin actuating the dock / undock carriage assembly 380 to close the locking arms 372 until they are fully closed in the outer locking grooves 352 and use the view from camera 42 to verify that the locking arms 372 have secured the safety valve assembly 350. g. Continue to drive the docking / disconnecting carriage assembly 380 until the quick connect nipple 355 of the safety valve assembly 350 is fully docked into the quick connect coupling 385, as confirmed by the dual microswitch assembly 387. h. Select Mechanism C, Wrench Up 20 in the transmission 26 and verify selection using the readout of the linear potentiometer 477. Using the view from camera 42, adjust mechanism C, wrench lift 20 so that wrench jaw 154 is aligned with coupling nut 353. Monitor end of travel microswitch 307 during motion. j. Use mechanism B1, wrench close / open 14, to close wrench jaws 154 on coupling nut 353 and verify condition using preload microswitch 169 while monitoring the view from camera 42. k. Select mechanism B2, wrench rotation 18 in transmission 26 and verify selection using linear potentiometer 477 readout. l. Mechanism B2, rotate coupling nut 353 with wrench rotation 18. Monitor the view from camera 42 during rotation and the readout from CW / CCW microswitch 266 and torque cell 201 at the end of mechanism travel. m. Use mechanism B1, wrench close / open 14 to open wrench jaws 154 from coupling nut 353 and verify condition using preload microswitch 169 while monitoring the view from camera 42. n. Mechanism B2, select wrench rotation 18 with transmission 26 and verify selection using linear potentiometer 477 readout. o. Using the view from camera 42, rotate mechanism B2, wrench rotation 18, to a new position on coupling nut 353. p. Repeat steps j. through o. until the relief valve assembly 350 is released from the storage post 82. q. Use mechanism B1, wrench close / open 14 to open wrench jaws 154 from coupling nut 353 and verify condition using preload microswitch 169 while monitoring the view from camera 42. r. Select mechanism D, FDV connection 22 at transmission 26 and verify selection using linear potentiometer 477 readout. s. Retract the safety valve carriage assembly 367 so that the safety valve assembly 350 is stored inside the refueling tool 10 for transport to the client satellite 81, and confirm using the retract microswitch 418 on the safety valve carriage assembly 367. t. Select Feature A, center and clamp 12 with transmission 26 and verify selection using linear potentiometer 477 readout. u. Release the clamp of Mechanism A from the storage post 82 and use the clamped microswitch 127 to verify that the clamp load has been removed from the storage post 82.

[0154] 7.4 Attach the SV to the client S / C - Fasten the SV fitting nut to the client FDV a. Touch down contact ball 490 on FDV bracket 52 and use the view from camera 42 to verify that both refueling tool 10 is lowered and that jaws 121, center and clamps 12 of Mechanism A are fully open. b. Select mechanism A, center and clamp 12 with transmission 26 and verify selection using linear potentiometer 477 readout. c. Mechanism A, center and clamp 12 clamps FDV reaction plane 58 and uses clamped microswitch 127 to verify that the clamp load is applied to the fill / drain valve, FDV 54. d. Mechanism D, select FDV connection 22 at transmission 26 and verify selection using linear potentiometer 477 readout. e. Advance the safety valve carriage assembly 367 until the coupling nut 353 contacts the fill / drain valve, FDV 54, as confirmed by the compliance microswitch 415. f. Select Mechanism C, Wrench Up 20 in the transmission 26 and verify selection using the linear potentiometer 477 readout. g. Using the view from camera 42, adjust mechanism C, wrench lift 20 so that wrench jaw 154 is aligned with coupling nut 353. Monitor end of travel microswitch 307 during motion. h. Mechanism B1, close / open wrench 14 is used to close wrench jaws 154 on coupling nut 353 and the preload microswitch 169 is used to verify condition while monitoring the view from camera 42. i. Select mechanism B2, wrench rotation 18 in transmission 26 and verify selection using linear potentiometer 477 readout. j. Mechanism B2, rotate coupling nut 353 with wrench rotation 18. Monitor the view from camera 42 during rotation and the readout from CW / CCW microswitch 266 and torque cell 201 at the end of mechanism travel. k. Use mechanism B1, wrench close / open 14 to open wrench jaws 154 from coupling nut 353 and verify condition using preload microswitch 169 while monitoring the view from camera 42. l. Select mechanism B2, wrench rotation 18 with transmission 26 and verify selection using linear potentiometer 477 readout. m. Using the view from camera 42, rotate mechanism B2, wrench rotation 18, to a new position on coupling nut 353. n. Repeat steps h. through m. until the safety valve assembly 350 is fastened to the fill / drain valve, FDV 54.

[0155] 7.7 Opening the valve actuating nut for fuel transfer a. Select Mechanism C, Wrench Up 20 in the transmission 26 and verify selection using the linear potentiometer 477 readout. b. Using the view from camera 42, adjust mechanism C, wrench lift 20 so that actuation nut 62 is aligned with wrench jaw 154. Monitor end of travel microswitch 307 during motion. c. Mechanism B1, close / open wrench 14 is used to close wrench jaws 154 on actuation nut 62 and the preload microswitch 169 is used to verify condition while monitoring the view from camera 42. d. Select mechanism B2, wrench rotation 18 in transmission 26 and verify selection using linear potentiometer 477 readout. Mechanism B2, use wrench rotation 18 to rotate actuation nut 62 and open for fuel transfer. Monitor the view from camera 42 during rotation and the readout from CW / CCW microswitch 266 and torque cell 201 at the end of mechanism travel.

[0156] 7.9 Close the operating nut after fuel transfer a. Using the view from camera 42, verify that wrench jaw 154 is still aligned with actuation nut 62. b. Mechanism B2, use wrench rotation 18 to rotate actuating nut 62. Monitor the view from camera 42 during rotation and the readout from CW / CCW microswitch 266 and torque cell 201 at the end of mechanism travel. c. Use mechanism B1, close / open wrench 14 to open wrench jaws 154 from actuation nut 62 and verify condition using preload microswitch 169 while monitoring the view from camera 42.

[0157] 8.3 Disconnect the Refueling Tool (RT) quick connect from the SV quick connect and remove the RT from the client valve a. Begin actuating the coupler / disconnect carriage assembly 380 until the quick connect nipple 355 of the safety valve assembly 350 is fully disconnected from the quick connect coupling 385, as confirmed by the dual microswitch assembly 387. b. Continue to drive the dock / undock carriage assembly 380 to open the locking arms 372 from the outer locking grooves 352 and use the view from camera 42 to verify that the locking arms 372 are fully open. c. Mechanism D, select FDV connection 22 at transmission 26 and verify selection using linear potentiometer 477 readout. d. Retract the safety valve carriage assembly 367 until it is fully retracted and confirm using the retract microswitch 418 on the safety valve carriage assembly 367. e. Select Mechanism A, center and clamp 12 with transmission 26 and verify selection using linear potentiometer 477 readout. f. Unclamp mechanism A, center and clamp 12 from FDV torque reaction plane 58 and use clamped microswitch 127 to verify that the clamp load has been removed from the fill / drain valve, FDV 54.

[0158] 9.1 Merge the RT quick connect to the quick connect of the Servicer S / C "Safety Valve Fixture" a. Touch down contact sphere 490 on servicer spacecraft 80 and use the view from camera 42 to verify that refueling tool 10 is lowered and that jaws 121, center and clamps 12 of mechanism A are fully open. b. Select Mechanism A, center and clamp 12 with transmission 26 and use the readout of linear potentiometer 477 to verify selection. c. Clamp safety valve fixture 83 with mechanism A, center and clamp 12 and use clamped microswitch 127 to verify that clamp load is applied to safety valve fixture 83. d. Mechanism D, select FDV connection 22 at transmission 26 and verify selection using linear potentiometer 477 readout. e. Advance the safety valve carriage assembly 367 until the trigger plate 407 contacts the shoulder of the safety valve retainer 83, as confirmed by the latch ready microswitch 408. f. Begin actuating the dock / disconnect carriage assembly 380 to fully close the locking arms 372 until the safety valve fixture 83 is fully closed, using the view from camera 42 to verify that the locking arms 372 have secured the safety valve fixture 83. g. Continue to drive the dock / disconnect carriage assembly 380 until the quick connect nipple on the relief valve fitting 83 is fully docked with the quick connect coupling 385, as confirmed by the dual microswitch assembly 387.

[0159] 9.3 Separating the RT quick connection from the "Safety Valve Fixture" quick connection on the Servicer S / C Continue to drive the coupler / disconnect carriage assembly 380 until the quick connect nipple on the safety valve fitting 83 is fully disengaged from the quick connect coupling 385, as confirmed by the dual microswitch assembly 387. b. Continue to actuate mechanism D2 to open locking arm 372 from safety valve fixture 83 and use the view from camera 42 to verify that locking arm 372 is fully open. c. Mechanism D, select FDV connection 22 at transmission 26 and verify selection using linear potentiometer 477 readout. d. Retract the safety valve carriage assembly 367 until it is fully retracted and confirm using the fully retracted microswitch 418. e. Select Mechanism A, center and clamp 12 with transmission 26 and verify selection using linear potentiometer 477 readout. f. Unclamp mechanism A, center and clamp 12 from safety valve fixture 83 and use clamped microswitch 127 to verify the clamp load has been removed from safety valve fixture 83.

[0160] Detailed Operation of DEE and Maintenance Tools This method can be applied in steps 1.1, 2.1, 3.1, 5.1, 6.1, and 10.1 of the overall operational FFBD for retrieving a maintenance tool. a. Command the robotic arm 84 to hoist high above the grapple fixture 610 of a tool (e.g., B nut removal tool 608, crush seal removal tool 609, blanket cutter tool 605, blanket handling tool 606, or wire cutter tool 607) at the stowage location. b. Command the robot arm 84 to fit within the capture envelope of the tool grabber fixture 610. c. Move the arm forward until the distal end of the grapple fixture 610 is within the capture envelope of the capture mechanism 551 of the fine end effector 550. d. The capture mechanism 551 of the dexterity end effector, DEE 550, firmly grasps the grapple fixture 610. e. With the fine end effector, DEE 550, replace the constraint mechanism active half 618 of the tool. f. Command the arm to move away from the storage area.

[0161] 1.3 Disconnect the blanket on the client S / C a. Switch to client satellite 81. b. Position the blanket cutter tool 605 on the thermal blanket. c. Pierce the blanket with the blanket cutter tool 605. d. Cut the blanket with blanket cutter tool 605. e. Repeat c and d until the blanket is completely cut. f. Command the arm to move away from the Client 81 satellite.

[0162] 3.2~3.5 Cut the B nut and operating nut lock wire on the client S / C a. Switch to client 81 satellite. b. Position the wire cutter tool 607 on the lockwire. c. Cut the lock wire with wire cutter tool 607. d. Repeat b and c until the wire is completely severed. e. Command the arm to move away from the Client 81 satellite.

[0163] 5.2~5.5 Remove the B nut from the client S / C and discard it at the servicer. a. Switch to client 81 satellite. b. Position the B nut removal tool wire 608 on the fill / drain valve, FDV 54. c. Seat the B nut removal tool wire 608 into the B nut 64. d. Capture B nut 64. e. Release the arm from the Fill / Drain Valve, FDV54. f. Transfer to the Servisa 80 spacecraft. g. Locate the tool at the disposal location. h. Command the B nut removal tool wire 608 to push out the B nut 64. i. Move the arm away from the disposal area.

[0164] 6.2~6.5 Remove the crash seal from the client S / C and dispose of it at the servicer. a. Switch to client 81 satellite. b. Position the crush seal removal tool 609 on the fill / drain valve, FDV54. c. Seat the crush seal 702 onto the crush seal removal tool 609 . d. Capture the crush seal 702. e. Release the arm from the Fill / Drain Valve, FDV54. f. Transfer to the Servisa 80 spacecraft. g. Position the crush seal removal tool 609 in the disposal area. h. Command the tool to push out the crush seal 702. i. Move the arm away from the disposal area.

[0165] This method can be applied in steps 1.5, 2.7, 3.6, 5.6, 6.6, and 10.5 of the overall operational FFBD for stowing the maintenance tool. a. Transfer to the Servisa 80 spacecraft. b. Command the arm to hoist high above a tool (eg, B-nut removal tool 608, crush seal removal tool 609, blanket cutter tool 605, blanket handling tool 606, or wire cutter tool 607) at the stowage location. c. Command the arm to the docking location. d. Attach the constraint mechanism active half 618 of the tool to the fine end effector, DEE 550. e. Float the tool's grapple fixture 610 to release it from the fine end effector, DEE 550. f. Command the arm to move away from the storage area.

[0166] 4.1, 7.1 Retrieve refueling tools. a. Command the arm to hoist high above the refueling tool 10 at the stowed location. b. Command the arm to fit into the capture envelope of the refueling tool 10 grapple fixture 610. c. Move the arm forward until the grapple probe is within the jaws of the grapple canister. d. Firmly grip the grapple fixture 610 with the precision end effector, DEE550. e. Providing electrical communication between the dexterity end effector, DEE550, and the refueling tool 10. f. Allows fluid communication between the fine end effector, DEE550, and the refueling tool 10. g. Resetting the tool constraint restraints with the precision end effector, DEE550. h. Command the arm to leave the storage area.

[0167] 4.7, 9.4 Store refueling tools. a. Transfer to the Servisa 80 spacecraft. b. Command the arm to hoist high above the refueling tool 10 at the stowed location. c. Command the arm to the docking location. d. Fasten the tool restraints with the precision end effector, DEE550. e. Disable electrical communication between the dexterity end effector, DEE550, and the tool. f. Disable fluid communication between the fine end effector, DEE550, and the tool. g. Float the tool's grapple fixture 610 to release it from the fine end effector, DEE 550. h. Command the arm to leave the storage area.

[0168] The present disclosure has advantages over previously disclosed systems as outlined below.

[0169] First, the vision system based open architecture enables verification of each successive access, clamp and rotation state of the FDV accomplished by refueling tool 10 in a refueling operation commanded by either a human remote operator or automated control. Verification of successful completion of each successive operational step of the FDV as part of a refueling operation is essential to meeting mission requirements.

[0170] Second, the vision-based architecture supports fine-tuning of individual mechanism motions in real time within a mission plan. Risks associated with unknown aspects of the as-built configuration, such as variations in torque reaction plane orientation or mounting tolerances, are mitigated, and each mechanism is adaptable to the FDV work site so that a variety of different work sites can be serviced with one tool.

[0171] Third, the means for aligning and clamping to the FDV allows one refueling tool to fit a wide range of FDV sizes and all possible orientations. A detailed examination of the FDV work site revealed that this compatibility is essential to ensure mission success.

[0172] Fourth, the wrench mechanisms that comprise these mechanisms for opening, closing, rotating, and height adjustment of the wrench can be adjusted to fit a wide range of FDV sizes and all possible installation configurations, and the wrench actions can be performed without obstructing the vision system, which is critical for verifying that operational steps were successfully accomplished.

[0173] Fifth, the use of a safety valve with a quick connect nipple provides two independent means of sealing the FDV after a refueling operation. The combination of the quick connect nipple and a second, separate check valve in series within the safety valve restores the two levels of sealing that existed before the service.

[0174] Sixth, the use of a safety valve with a quick connect nipple facilitates a significantly simplified sequential refueling operation. More specifically, in its simplest form, in a second refueling operation of a client satellite, the refueling operation would begin at step 7.0 of Figure 56B.

[0175] Seventh, the use of a safety valve with a quick connect nipple provides a means for refueling without the need for any rotational actuation on a threaded connection. This is a direct improvement over the prior disclosure by eliminating the possibility of rotation of not only the actuation nut but the entire safety valve body, as may occur, for example, if the safety valve includes a rotating actuation nut on its threaded connection to the FDV.

[0176] Eighth, installation of the safety valve via the threaded coupling nut occurs only after the refueling tool is successfully aligned and clamped to the target FDV, unlike previously disclosed systems in which the robotic arm with the refueling tool and safety valve approaches the FDV without alignment. Further, installation of the safety valve to the FDV includes both visual and microswitch-based sensing in conjunction with the compliant coupling nut to ensure successful threaded engagement.

[0177] Ninth, with regard to the overall refueling system and method, a comprehensive set of tools provides a means and method for robust verifiability of every step through visual and other sensor means. All tooling operations are robust because they can be adjusted in real time on-orbit to accommodate for variations in job site configuration of mechanism tolerances. At each step of the refueling operation where the blanket, lock wires, and FDVs are manipulated, sensor information allows for confirmation of the information required to perform successful or recovery operations.

[0178] Tenth, the support maintenance tools have a means to be picked up, powered, and stowed through the action of a single robotic arm and end effector. The prior art has shown a means to stow the maintenance tools but has not provided sufficient restraint for launch or transport. [Explanation of symbols]

[0179] An embodiment of the refueling tool, with reference to the drawings, comprises the following components: 10: Refueling tool 12: Mechanism A, center and clamp 14: Mechanism B1, wrench closed / open 16: Compliance Organization 18: Mechanism B2, wrench rotation 20: Mechanism C, wrench up 22: Mechanism D, FDV connection 26: Transmission 40: Refueling Tool Vision System Based Architecture 42: Camera 44: Camera bracket 46: Camera shield 50: FDV work site 52: FDV bracket 54: Fill / Drain Valve, FDV 56: Valve body 58: Torque reaction plane 60:FDV axis 62: FDV operating nut 64: B Nut 66: FDV flange 68: FDV welded joint 70:FDV nipple 80: Servisa spacecraft 81: Client 82: Storage post 83: Safety valve fixing 84: Robot arm 102: Mechanism “A” input shaft 103: Thrust ball bearing 104: Thrust needle roller bearing 105: Tension box 106: Lead Nut 107: Piston 108: Cross pin 109: Spring 110: Spacer 111: Spacer 112: End cap 113: Tension assembly 114: Linear bearing rail 115: Linear bearing block 116: Drive link 117: Rocker arm 118: Connection link 119: Push rod 120: Bushing 121: Jaw 122: Pivot 123: Laura 124: Roller bracket 125: Grip part 126: Contact finger 127: Microswitch 128: Mechanism "A" Frame 129: Mechanism A mounting interface 150:B1 lead screw 151: Lead screw drive gear 152: B1 cabinet 153:B1 cover 154: Wrench jaw 155: Lead Nut 156: Nut clamp 157: Locking pin 158: Idle Gear 159: B1 drive input gear 160: B1 drive actuator 161:B1 actuator adapter 162: B1 housing actuator recess 163: Retaining clip 164: Actuator adapter pin 165: Plunger guide 166: Plunger spring 167: Plunger 168: Plunger branch head 169: Microswitch 170:B1 mounting protrusion 171: Shoulder bolt 172: Bearings 173: Idler shaft 174: Idler bearing 175: Torque reaction recess 176: Torque reaction shaft 200: Torque cell plate 201: Torque cell 202: Coupling bracket 203: Downsweep protrusion 204: Coupling platform 205: Projection 206: Ball bushing 207: Bushing circlip 208: First pair of precision shafts 209: Second pair of precision shafts 210: Adjustable length locking shaft collar 211: Compression spring 212: Compliance mechanism mounting interface 250: Rotating track plate 251: B2 drive gear 252: Internally splined hub 253:B2 drive housing 254: Bearing 255: Thrust pad 256: Segment gear assembly 257: Segment gear 258: Segment gear carrier 259: First pair of track rollers 260: Moving end pin 261: Tensioner assembly 262: Tensioner yoke 263: Second pair of track rollers 264: Tension screw 265:Disc spring 266: Microswitch 267: Microswitch spacer 268: Precision rolled surface 269: Segment gear bumper 270: Wrench shaft 271: Height movement indicator 272: Interface to mechanism A 300: Refueling tool back plate 301: Refueling tool intermediate plate 303: Linear bearing rail 304: Linear bearing block 305: Right angle bracket 306:Non-metallic bumper 307: Reverse micro switch 308: Bearings 309: Mechanism B2 spline shaft 310: Mechanism C lead screw 311: Extension micro switch 350: Safety valve assembly 351: Safety valve body 352: External lock groove 353: Coupling nut 354: Spring 355: Quick connect nipple 356: Check valve 357: Safety valve shoulder 360: Mechanism D base plate 361: Hose bracket 362: First set of linear guide rails 363: Adjustable end stops 364: Dual microswitch assembly 365: Flexible hose 367: Safety valve carriage assembly 368: Safety valve carriage 369: Linear guide block 370: Locking arm post 371: Flanged bushing 372: Rocking Arm 373: Activation slot 374: Safety valve sensor assembly 375:Compliant Coupling Assembly 376: First actuation actuator 377: Microswitch striker 378: Second set of linear guide rails 380: Connect / disconnect carriage assembly 381: Coupling / separating carriage 382: Linear guide block 383: Track roller 384: Lead Nut 385: Quick connect coupling 386: Propellant Manifold 387: Dual microswitch assembly 388: Travel Stop 390: Splined input shaft 391: Drive bracket 392: Gear 393: Bearings 394: Safety valve lead screw 395: Lead Nut 396: Guide housing 397: Guide pin 398: Connection pin 400: Compliance housing 401: Compliance Base 402:Shuttle 403: Spring 405: Sensor housing 406: Sensor base 407: Trigger plate 408: Latch ready microswitch 409: Spring 410: Restriction pin 415: Compliance micro switch 416: Compliance Striker 417: Forward microswitch 418: Reverse microswitch 450: Transmission housing 451: Top cover 452: Lower cover 453: Gear 454: Input gear 455: Input gear common shaft 456: Output gear 457: Internally splined hub 458: Bearings 459: Support case 460: Thrust washer 461: Full rim 462: Partial rim 463: Cylindrical groove 464: Housing bore 465: Positioning pin hole 466: Positioning pin 467: Transmission housing mounting interface 470: Transmission bracket 471: Linear guide rail 472: Linear guide block 473: Transmission support plate 474: Lead Nut 475: Nut clamp 476: Linear potentiometer 477: Potentiometer mounting fixture 478: Potentiometer rod bracket 479: Refueling tool upper plate 480: Transmission lead screw 481: Bearings 482: Bearing retainer 483: Refueling tool side plate 484: Transmission lead screw 485: Transmission range 490: Contact ball 491: Touchdown Rod 492: Touchdown Arm 493: Touchdown bracket 500: Refueling Tool End Effector Interface 501: Gripping fixture 502: 1st rotating input shaft 503: Second rotating input shaft 504: Electrical connectors 505: Quick connect nipple 506: Target 507: 1st rotation input gear 508: Transfer gear 509: Quill Axis 510: Bearings 511: Retainer 512: Quill shaft external spline 513: Fuel Channel 514: Quill shaft drive gear 515: Transmission housing 516: Grapple Fixture Probe 550: Precision End Effector, DEE 551: Capture mechanism 552: 1st rotary input socket 553: 2nd rotary input socket 554: Movable Electrical Connector 555: Movable quick connect propellant coupling 556: End effector camera 601: Maintenance support tools, general purpose 603: General tool base 605: Blanket cutter tool 606: Blanket handling tool 607: Wire cutter tool 608: B nut removal tool 609: Crush seal removal tool 610: Grapple fixing device 612: Tool mechanism drive interface, primary 613: Tool mechanism drive interface, secondary 614: Tool mechanism gear train 618: Restraint mechanism active half 620: General tool base structure 630: Example of a general-purpose tool tip 632: Tool Mechanism Gear Train Interface 634: Tool tip drive shaft 636: General structure of tool tip 638: Tool base to tool tip bolted interface 640: Forward threaded rod 642: Input linkage 644: Output linkage 645: Cutting shears 646: Grip paddle 647: Wire cutter shears and wiring gripping mechanisms 650: Blanket cutter tool tip 652: Blanket handling tool tip 654: Wire cutter tool tip 660: B nut removal tool tip 662: Colette 664: Drive shaft 666: Campin 668: Cam pin slot 670: Spring wrench finger 672: B nut hexagonal nut mechanism 674: Ratchet disc interface 676: Pin carrier housing 678: Ratchet disc 680: Tool tip base structure 682: Key mechanism 684: Preload spring 686: Ratchet disk surface with ramp mechanism 688: Surface of pin carrier housing having ramp mechanism 700: Crush seal removal tool tip 702: Crush seal, part of FDV 704: Drive shaft 706: Plunger 708: Drive shaft to plunger threaded interface 710: Pivot point 712: Flex Jaw Linkage 714: Flex jaw tip 716: FDV valve stem 718: Cage 719: Tool tip base structure 720: Plunger face 730: Tool constraint, tool side 732: Tool restraint, receptacle 734: Visual cues 736: Spline, receptacle 738: Drive shaft 740: Spline, tool side 742: Ball lock sleeve 744: Rock Ball 746: Ball notch 748: Restraint body 750: Ball lock sleeve protrusion 752: Spring-loaded indicator 800: Command and Control Systems 802: Bus 813: Communication interface 825: Computer Control Systems 830: Processor 835: Memory 845: Power supply 850:Robot Vision System 860: I / O Devices and Interfaces 862: Propellant Transfer Flow Control System 930:Communication Systems 934: Two-way radio link 940:Earth 950: Mooring equipment 960: Propellant Transfer System 980: Propellant outlet hose

Claims

1. 1. A method for transferring propellant from a servicer spacecraft to a client spacecraft, comprising: the servicer spacecraft includes a robotic arm and a refueling tool mountable on the robotic arm, the refueling tool having a refueling tool vision system including at least one camera, a rotatable wrench, and an open architecture structure, such that when the refueling tool is engaged with a fill / drain valve, a field of view of the camera encompasses the engaged fill / drain valve, the rotatable wrench of the refueling tool, and a coupling nut of a safety valve mounted to the fill / drain valve; and a sensor strategically positioned on a selected moving component of the refueling tool to sense a position of the selected moving component during a refueling operation; the client spacecraft includes a tank and a fill / drain valve coupled to the tank, the fill / drain valve including a valve actuating nut for opening and closing the fill / drain valve, and the propellant is selected from the group consisting of a fuel and an oxidizer; a. removing an access valve cap of the fill and drain valve; b. providing sensory confirmation that the removal operation was successful; c) establishing a fluid connection between a safety valve of the servicer spacecraft and a source of propellant through a fluid line connected at one end to the source of propellant; d. providing a sensory confirmation that the connection has been established; e. attaching the safety valve to the fill and drain valve to provide a safety fluid coupling that allows one-way fluid flow into the fill and drain valve; f. providing sensory confirmation that the relief valve is installed; g. opening the fill and drain valves by actuating the valve actuation nut; h. providing sensory confirmation that the actuation nut has been actuated; i. transferring the propellant through the safety valve and into the tank; directing the robotic arm to position the refueling tool to perform The step of providing sensing confirmation is accomplished using a combination of feedback provided by real-time visual images from the refueling tool vision system and simultaneous real-time feedback from sensors located on components of the refueling tool to sense the positions of moving components of both the servicer spacecraft and the client spacecraft engaged by the refueling tool during all steps of the refueling operation.

2. The method of claim 1, wherein the movable components include the access valve cap, the safety valve, the fluid line, the fill and drain valve and the valve actuation nut.

3. 1. A method for refueling a client satellite by accessing one or more fill and drain valves in fluid communication with one or more propellant storage tanks disposed on the client satellite, comprising: a) one or more safety valves; b) a refueling tool having a refueling tool vision system including at least one camera, a rotatable wrench, and an open architecture structure, such that when the refueling tool is engaged with a fill / drain valve, the field of view of the camera encompasses the engaged fill / drain valve, the rotatable wrench of the refueling tool, and a coupling nut of a safety valve installed on the fill / drain valve, and including sensors strategically positioned on selected moving components of the refueling tool to sense the position of the selected moving components during a refueling operation; c) a set of support tools for preparing the client satellite to receive the refueling tool and for assisting in the refueling operation, a) a robotic arm attached at a proximal end to the servicer spacecraft; b) a tether for fixedly connecting the client satellite to the servicer spacecraft; and c) a propellant transfer system for transferring propellant from the servicer spacecraft to the client satellite; and d) the method of refueling is performed using the servicer spacecraft having attached thereto a propellant coupling, the propellant coupling being attached to an end effector connected to the propellant transfer system for transferring propellant to the client satellite through the propellant coupling; The method of refueling comprises: i) maneuvering a servicer satellite into close proximity with said client satellite and tethering said client satellite to said servicer satellite using a tethering device; ii) directing the robotic arm to sequentially capture the refueling tool and the support tool and to loosen and remove any objects covering the fill / drain valve, thereby exposing the fill / drain valve, whereupon the removal of any objects retracts the refueling tool and exposes the fill / drain valve; iii) after the fill / drain valve is exposed, directing the robotic arm to capture the refueling tool configured to establish a fluid connection between the safety valve and the one or more propellant storage tanks located on the servicer spacecraft, and once captured, directing the robotic arm to capture a safety valve, thereby connecting the propellant transfer system to the safety valve; iv) directing the robotic arm to place the safety valve on the refueling nipple of the fill and drain valve based on real-time visual images obtained by the refueling tool vision system and feedback from one or more sensors located on components of the refueling tool, and sensing the positions of moving components of both the servicer spacecraft and the client satellite engaged by the refueling tool during a refueling operation; v) transferring the propellant through the refueling tool and through the safety valve to the client satellite; vi) once the propellant has been transferred, directing the robotic arm to disconnect the refueling tool from the fill / drain valve thereby disconnecting the propellant transfer system; vii) releasing the tether from the client satellite and providing sensory confirmation that each operation was successful; and Equipped with A method of refueling, wherein the step of providing sensing confirmation is accomplished using a combination of feedback provided by real-time visual images from the refueling tool vision system and simultaneous real-time feedback from sensors located on components of the refueling tool to sense the positions of moving components of both the servicer spacecraft and the client satellite engaged by the refueling tool during all steps of the refueling operation.

4. The method of claim 3 , further comprising recording an output of the one or more sensors.

5. The method of claim 3 , wherein the sensor is any one or combination of one or more microswitches and one or more potentiometers.

6. The method of claim 5, wherein the feedback from one or more of the microswitches and / or potentiometers is the state of the microswitch at a particular time during the refueling operation.

7. 7. The method of claim 6, wherein the microswitch is located within a mechanism tasked with placing the safety valve on the fill / drain valve so as to sense the safety valve during capture and to sense a safety valve coupling nut of the safety valve contacting the refueling nipple of the fill / drain valve during a refueling operation.

8. 1. A system mounted on a servicing spacecraft for transferring a fluid to a client satellite, the client satellite including a tank and a fill and drain valve, the tank coupled to the fill and drain valve, the fill and drain valve having an actuation nut for opening and closing the fill and drain valve, and an access valve cap on the fill and drain valve; a) a fluid transfer means for transferring a fluid from a fluid tank of the servicing spacecraft to the tank of the client satellite, the fluid being selected from the group consisting of fuel and oxidizer; b) tool means for removing and replacing said access valve cap, for connecting and disconnecting fluid lines to and from said fill and drain valve, and for actuating said valve actuation nut to open and close said fill and drain valve; c) first sensing means for determining relative displacement between said tool means and said fill / drain valve, said first sensing means being positioned to have a field of view to monitor said relative displacement between said tool means and said fill / drain valve throughout a refueling operation; d) second sensing means including one or more sensors embedded in said tool means for sensing and recording the position of selected moveable components during a fluid transfer operation to access and manipulate said fill and drain valve and thereafter determine the state of said fill and drain valve during subsequent steps of connecting and disconnecting said fill and drain valve to and from said fluid line; e) a safety valve attachable to said fill / drain valve to provide a safe fluid coupling with said safety valve having one or more independent seals against leakage during and after the refueling operation; f) positioning means connectable to said tool means for positioning said tool means relative to said fill / drain valve; g) control means in communication with said first and second sensing means, said positioning means, and said tool means for controlling operation of said positioning means and said tool means based on feedback from said first and second sensing means; and h) said tool means having an open architecture configuration, said field of view of said first sensing means remaining clear during a refueling operation and feedback from both said first and second sensing means enabling sensing of the position of moving components of both said servicing spacecraft and said client satellite engaged by said refueling tool during all steps of the refueling operation; A system comprising:

9. The tool means comprises: a first tool operable to loosen the access valve cap and open and close the valve actuation nut to connect and disconnect the fluid lines to and from the fill and drain valve; a second tool for removing the access valve cap; The system of claim 8 , comprising:

10. 10. The system of claim 8 or 9, wherein the tool means includes a third tool for removing a crush seal from the fill and drain valve.

11. 11. The system of claim 8, 9 or 10, wherein the first sensing means is a vision system.

12. The second sensing means is a vision system positioned to have a field of view that encompasses a working space including the first and second tools engaged with the fill and drain valve; said sensing means embedded in said tool means; The system according to any one of claims 8 to 11, wherein

13. 13. The system of claim 12, wherein the sensing means is one or more microswitches, one or more potentiometers, or any combination thereof.

14. The system described in claim 13, wherein the feedback from one or more of the microswitches and / or one or more potentiometers is the state of the microswitch and / or the state of the potentiometer at a particular time during the refueling operation.

15. a refueling tool mounted on a servicing spacecraft for opening and closing one or more fill / drain valves of a client satellite being refueled with the one or more fill / drain valves in fluid communication with a fuel tank of the client satellite, the one or more fill / drain valves having rotatable and static mechanisms coaxially aligned along a first axis, the servicer spacecraft including a safety valve that is installed and stowed in the fill / drain valves during refueling prior to passing fuel through any safety valves and their associated fill / drain valves, and further including a refueling system configured to be coupled to the safety valves during a refueling operation; a) a mechanism A for aligning and clamping to the fill / drain valve body and torque reaction plane of a target fill / drain valve; A rotatable wrench; A mechanism B1 for opening and closing the rotatable wrench; a mechanism B2 for rotation of the rotatable wrench about the first axis, the mechanism B2 having the mechanism B1 attached thereto dependently; a mechanism C for adjusting the height of the rotatable wrench; said mechanism B2 attached to mechanism C, whereby, as required, said mechanisms A, B1, B2 and C form a substructure forming a torque reaction loop ensuring that the torque induced by rotating the rotatable wrench is reacted in the valve body via the torque reaction plane; b) a mechanism D for connecting the refueling system to a refueling nipple of the engaged target fill and drain valve, the mechanism D being connected to the base structure and to a top plate connected to the base structure by side plates to form an overall refueling tool structure; an end effector interface connected to the top plate and configured to grasp and mate with a robot end effector attached to a robot arm attached to the servicer spacecraft; one or more sensors disposed within mechanism D for sensing the safety valve during capture and sensing a safety valve coupling nut of the safety valve contacting the refueling nipple of the fill / drain valve during a refueling operation; a tool vision system including at least one camera mounted on the refueling tool structure, wherein the undercarriage has an open architecture such that when the refueling tool engages a fill / drain valve, a field of view of the at least one camera encompasses the engaged fill / drain valve, the rotatable wrench of the refueling tool, and a coupling nut of the safety valve, as during the refueling operation, and the status of all of the rotatable wrench, the fill / drain valve, and the safety valve can be sensed and / or monitored using a combination of microswitch states and real-time images from the at least one camera; A refueling tool comprising a refueling tool structure including:

16. 16. The tool of claim 15, wherein the one or more sensors are one or more microswitches and the feedback from the one or more microswitches is a state of the microswitch at that particular time during the refueling operation.

17. 17. The tool of claim 16, wherein the one or more sensors are one or more microswitches, one or more potentiometers, or any combination thereof.

18. The set of support tools comprises: a set of tools, each having a specific function, each tool having a drive shaft and a tool section configured for that specific function; a common base to which a tool tip of each tool of the suite is permanently attached, a housing having a gripping interface on one side thereof configured for robotic gripping by an end effector mounted on a distal end of a robotic arm mounted on a servicing satellite, the gripping interface including a grapple fixture, and a housing having a tool mounted on its other side configured to receive the drive shaft of the tool; two tool mechanism drive interfaces used to perform any tool tip function via a drive actuator mechanism located on the end effector of the robot arm, one of the two tool mechanism drive interfaces being used to drive a specific tool tip of each of the support tools and the second one being used to drive a constraint storage mechanism for holding the common base when not being grasped by the robot arm; a tool mechanism gear train disposed within the housing for transmitting rotation and torque from one of the tool mechanism drive input interfaces to the tool drive shaft via a tool mechanism gear train interface for actuation of a tool function; and a common base including a constraint mechanism "active half" that is coupled to and driven by the second tool mechanism drive interface for use in holding the common base to the constraint mechanism when not in use and separated from the end effector.

19. 20. The method of claim 18, wherein the restraint mechanism comprises a receptacle housing secured to the servicing spacecraft having a passive locking mechanism configured to receive the tool held on the common base and engage and lock with the restraint mechanism "active half" of the common base.

20. 20. The method of claim 19, wherein the common base and the receptacle housing include visual cues that visually assist the robotic arm in aligning the common base with the receptacle housing during insertion and locking of the common base into the receptacle housing.

21. 21. The method of claim 18, 19, or 20, wherein the suite of support tools each includes a common base and a tool tip attached thereto, each tool tip including a site preparation tool having a specific device motion mechanism, the tool tip common structure including a housing having an interface configured to be bolted to the common base, a female threaded drive shaft having a portion extending from the housing that is inserted into the common base for engaging one of the two mechanism drive interfaces, a forward male threaded rod threadably mounted on a portion of the drive shaft located inside the housing, and a series of input linkages and a series of output linkages located at a distal end of the common structure, wherein rotation of the drive shaft causes linear movement of the forward threaded rod which in turn moves the series of input linkages which in turn pivotally connects output linkages that form part of the device motion mechanism about a specific point on any tool tip to open or close the device motion mechanism depending on the direction of movement.

22. 22. The method of claim 21, wherein the support tool suite includes a thermal blanket shearing device such that the operating mechanism of the device is a pair of cutting shears integrally formed with a distal end of the output pivot connection output linkage to provide a cutting action.

23. 22. The method of claim 21, wherein the support tool suite includes a thermal blanket handling device such that the motion mechanism of the device is a pair of blanket paddles integrally formed with a distal end of the output pivot connection output linkage to provide a gripping action for gripping and removing thermal blanket pieces.

24. 22. The method of claim 21, wherein the support tool suite includes a wire cutter and a gripping tool such that the motion mechanism of the apparatus is a pair of wire cutter shears having a wiring gripping mechanism integrally formed with a distal end of the output pivot connection output linkage to provide a gripping action for gripping and severing wire.

25. The support tool suite includes a crash seal removal tool for removing a crashed seal created when a fill / drain valve B nut is removed, the crash seal removal tool including the common base and a crash seal removal tool tip attached thereto, the crash seal removal tool tip including an interface configured to be bolted to the common base, a female-threaded rotatable drive shaft having a portion inserted into the common base to engage one of the two mechanism drive interfaces, and a male-threaded plunger partially received in the female-threaded drive shaft and movable relative thereto, the plunger having a distal plunger face including a pair of flex jaw linkages pivotally connected together with a pivot point, the flex jaw linkages each having a distal flex jaw tip ...

21. The method of claim 18, 19, or 20, wherein the drive shaft extends through an opening in a cage fixedly attached to a tool tip base structure, and as the drive shaft rotates, a plunger moves rearwardly into the drive shaft, and as the plunger moves, the pivot point of the flex jaw linkage moves with the plunger, closing and retracting the flex jaw tip, contacting a valve stem of the fill / drain valve and retracting along the fill / drain valve stem, the flex jaw tip being preloaded against the fill / drain valve stem, hooking onto the crush seal and retracting until it is loosened by a force where it is trapped in the cage between the flex jaw tip and the distal plunger face, and rotation of the drive shaft in the reverse direction opens the flex jaw tip and ejects the crush seal from the tool tip by pushing the plunger face forward and out of the cage.

26. The support tool suite includes a B nut removal tool including a common base and a B nut removal tool tip permanently attached thereto, the B nut removal tool tip including a tool tip base structure permanently attached to the common base, a drive shaft having a portion inserted into the common base for engaging one of the two mechanism drive interfaces, a spring wrench finger coupled to a distal end of the drive shaft, and a collet having a keyed connection to the spring wrench finger at a proximal end of the spring finger to allow movement only along an axis of rotation of the drive shaft, the collet having a slot in an outer diameter of the collet and surrounded by a pin carrier housing and including a cam pin attached to the pin carrier housing extending within the slot, the pin carrier housing being engaged to the pin carrier housing at a ratchet disk interface by a preload spring, rotation of the ratchet disk being limited by a keyed mechanism between the ratchet disk and the tip base structure.

21. The method of claim 18, 19 or 20, wherein the collet is delayed from rotation by the ratchet disk via preloading against the B-nut, and in order for the pin carrier housing to rotate with the drive shaft, the collet must move axially forward as driven by the cam pin of the slot until an end of the slot forces the collet to close on the B-nut against the hex feature of the B-nut, and continued drive shaft rotation causes rotation of the pin carrier housing, the collet encircling the spring fingers and B-nut while the preload force of the preload spring of the ratchet disk interface is overcome allowing the pin carrier housing surface having a ramp feature to repeatedly slide over the ratchet disk surface having a ramp feature, whereby the collet can be retracted by unscrewing the B-nut from the FDV and reversing rotation of the drive shaft allowing the spring fingers to open so that the B-nut is no longer contained and can be discarded.

Images