Robotic systems, methods, and devices for grappling and actuating payloads - Patents.com

Abstract

A robotic system, method, and device for grappling and actuating a payload is provided. The robotic end effector device includes a grapple mechanism for capturing and rigidifying a payload through a grapple fixture. The grapple mechanism grapples a probe of the grapple fixture, retracts the probe, and matingly connects a first coupling element of the grapple fixture with a second coupling element on the grapple mechanism. Each coupling element includes a plurality of radially arranged teeth and notches that are configured to mate with the notches of the other coupling element. The grapple mechanism includes a payload presence sensor for sensing the presence of the probe in the grapple mechanism to initiate grappling, and a calibration sensor for tracking a position of a moving component of the grapple mechanism. Retraction of the moving component is stopped at a target preload position based on the position tracking.

Description

[Technical field]

[0001] The following relates generally to robotic systems and devices, and more specifically to a robotic interface for grappling and actuating a payload via a prepared interface on the payload. [Background technology]

[0002] The development of low-mass active robotic interfaces that operate at the end of manipulators is a key element in advancing robotic servicing, maintenance, and assembly capabilities, especially in space and orbital environments. One objective is to limit the mass and volume of robotic devices while maximizing the load capacity of the design. The development of multi-purpose robotic interfaces will encourage spacecraft integrators to incorporate robotic compatibility into future vehicles and architectures.

[0003] More generally, it is desired to have a robotic interface that enables effective capture of a payload (e.g., a tool or other object) in a variety of applications and environments, including space and orbital applications. Additionally, it is desired to have a robotic interface that can enable actuation of the captured payload, such as through maneuvering the captured payload via a pick-and-place operation, or through transmitting torque across the robotic interface. In other cases, there may also be transfer of data, power, and fuel. Summary of the Invention [Problem to be solved by the invention]

[0004] Thus, a need exists for improved systems, methods, and devices for grappling and actuating payloads that overcome at least some of the shortcomings of existing systems and methods. [Means for solving the problem]

[0005] A robotic end effector device is provided having an arm interface end including a robot arm interface for connecting to a robot arm, and a payload interface end for interfacing with a payload, the payload having a grapple fixture including a first coupling element and a grapple probe mounted on a surface of the payload.

[0006] The device includes a housing for enclosing an internal compartment of the end effector device; a second coupling element connected to the housing at a payload interface end for mating with the first coupling element during rigidification of the end effector to a payload, the second coupling element having an opening therethrough that allows a grapple probe of the grapple fixture to enter the internal compartment when the payload interface end is moved by the robotic arm toward the grapple fixture; and a grapple mechanism disposed within the internal compartment for capturing and rigidifying the payload through the grapple fixture to the end effector device.

[0007] The grapple mechanism includes a jaw assembly including jaws for grappling the grapple probe; a payload presence sensor for sensing that the grapple probe is in a position to be grappled by the jaws (the "grappling position"); and a translation component for translating along a capture axis of the grapple mechanism in a direction opposite the payload interface end (the "retract") to mate and connect the first coupling element and the second coupling element while the jaws are grappling the grapple probe to rigidify the end effector to the payload up to the target preload. The moving component includes a jaw assembly, where retraction of the moving component closes the jaws and grapples the grapple probe, and the grapple mechanism further includes: a translation mechanism for retracting the moving component along the capture axis; a motor for driving the translation mechanism, the motor being triggered to drive the translation mechanism in response to a payload presence sensor sensing the grapple probe in a grappling position; a calibration sensor for sensing retraction of the moving component from a calibration position; and a position monitoring device for monitoring a position of the moving component relative to the calibration position and for generating an output to stop retraction of the moving component when the moving component reaches a target preload position along the capture axis that achieves the target preload.

[0008] Also provided is a robotic end effector device having an arm interface end including a robotic arm interface for connecting to a robotic arm, the device further having a payload interface end for interfacing with a payload having a grapple fixture for grappling and rigidifying the payload and a torque element for receiving torque.

[0009] The device includes a grapple mechanism configured to grapple a grapple probe of the grapple fixture when the payload interface end of the end effector device is moved toward the grapple fixture and configured to retract the grappled probe along a capture axis toward the arm interface end and direct a coupling element and a torque element of the grapple fixture toward the payload interface end; and a socket drive mechanism for passing torque to the payload through the torque element on the payload.

[0010] The socket drive mechanism includes a socket module having a socket for receiving and seating a torque element; a socket rotator for rotating the socket to impart rotational mechanical energy to a torque element seated in the socket; a socket drive motor module for driving rotation of the socket rotator; and an axial compliance mechanism configured to passively axially retract the socket module from a forward position when the socket is misaligned with and in contact with the torque element, and to passively return the socket module to the forward position when the socket is aligned with and seated on the torque element.

[0011] The socket drive motor drives rotation of the socket rotator when the socket is seated on the torque element to impart rotational mechanical energy to the torque element.

[0012] Also provided is a method of robotic capture of a payload, the method including: moving a payload interface end of an end effector via a robotic arm towards a grapple fixture over a payload, such that the grapple fixture is within a capture envelope of the end effector, the payload interface end having a grapple mechanism; and sensing that a probe of the grapple fixture is within a grappling area of ​​the grapple mechanism where the grapple jaws of the grapple mechanism can grapple the probe.

[0013] In response to sensing that the grapple probe is within the grappling area, the method further includes the steps of retracting the grapple mechanism along the capture axis, closing the grapple jaws and grappling the probe; and sensing that the grapple mechanism has retracted from the home position.

[0014] In response to sensing that the grapple mechanism has been retracted from the home position, the method further includes tracking a position of the grapple mechanism along the capture axis via the position monitoring device as the grapple mechanism is retracted; retracting the grapple mechanism further along the capture axis to a target preload position as the grapple mechanism grapples the probe, retracting a first coupling element of the grapple fixture on a surface of the payload into a mated connection with a second coupling element on the payload interface end of the end effector, the first and second coupling elements being adapted to transmit a static load between each other without interface separation up to a maximum rigidified load capacity of the end effector, the target preload position corresponding to a respective rigidified load; generating an output at the position monitoring device when the grapple mechanism has been retracted to the target preload position; and stopping retraction of the grapple mechanism at the target preload position based on the output of the position monitoring device.

[0015] Also provided is a method of robotically transmitting torque to a payload that includes capturing a payload with an end effector by grappling a grapple fixture on the payload with a grapple mechanism of the end effector, retracting the grapple mechanism to a target preload position to rigidify the grapple fixture to the end effector, seating a torque element present on the payload in a socket of a socket drive mechanism of the end effector through relative motion of the payload and the end effector resulting from retraction of the grapple mechanism, and sensing that the torque element is seated in the socket of the socket drive mechanism.

[0016] In response to sensing that the torque element is seated in the socket, the method also includes applying a torque to the torque element by rotating the socket to drive a torque-driven subsystem of a payload connected to the torque element.

[0017] Other aspects and features may become apparent to those of ordinary skill in the art upon review of the following description of several exemplary embodiments.

[0018] The drawings included herein are intended to illustrate various examples of the articles, methods, and apparatus herein. [Brief description of the drawings]

[0019] [Figure 1A] FIG. 1 is a block diagram of a system for robotic capture of and torque transfer to a payload via a provisioned interface on the payload, according to an embodiment. [Figure 1B] FIG. 1B is a block diagram of a machine vision system of the system of FIG. 1A. [Figure 1C] FIG. 1B is a block diagram of a grapple subsystem of the system of FIG. 1A. [Figure 1D] FIG. 1B is a block diagram of a torquer subsystem of the system of FIG. 1A. [Diagram 2] 1 is a flow diagram of a method for interfacing between a multi-purpose end effector and a prepared payload, according to an embodiment. [Figure 3A] 1 is a flow diagram of a method for grappling and rigidifying a payload via a grapple fixture on the payload, according to an embodiment. [Figure 3B] 1 is a flow diagram of a method for grappling and rigidifying a payload via a grapple fixture on the payload, according to an embodiment. [Figure 4]1 is a flow diagram of a method for aligning, seating, and actuating a torque element (or torque or actuating member) on a payload prepared interface, according to an embodiment. [Diagram 5] FIG. 1 illustrates a perspective view of a robot interface system including a prepared interface for use on a payload and a robot end effector for interfacing with the payload via the prepared interface, according to an embodiment. [Figure 6A] FIG. 6 is a front perspective view of the end effector of FIG. 5 in a separated state. [Figure 6B] FIG. 6B is a rear perspective view of the end effector of FIG. 6A. [Figure 7A] FIG. 6B is an exterior side view of the grapple mechanism of the end effector of FIG. 6A in a separated state. [Figure 7B] FIG. 7B is an exterior front view of the grapple mechanism of FIG. 7A. [Figure 8] FIG. 7C is a front perspective view of a front end of the grapple mechanism of FIGS. 7A-7B. [Figure 9] FIG. 6 is a perspective view of the grapple fixture of FIG. 5 in a detached state. [Figure 10A] 10 is a perspective view of the front end of the end effector of FIG. 8 and the grapple fixture of FIG. 9 in a pre-capture configuration as the end effector moves towards the grapple fixture. [Figure 10B] 10 is a perspective view of the end effector front end of FIG. 8 and the grapple fixture of FIG. 9 in a post-capture and rigidified configuration showing the coupling of the respective coupling elements of the end effector and the grapple fixture. [Figure 11] FIG. 7 is a cross-sectional side view of a grapple mechanism of the end effector of FIGS. 6A-B in a separated state, according to an embodiment. [Figure 12A] 12 is a cross-sectional side view of the grapple mechanism of FIG. 11 after contact with the grapple fixture and during mechanism retraction. [Figure 12B] FIG. 12B is a cross-sectional side view of the interface between the grapple mechanism and grapple fixture of FIG. 12A, rigidified through Belleville spring stack compression via relative motion between the split housing and the screw sleeve. [Figure 13A] 12 is a partially transparent perspective side view of the grapple jaws of the grapple mechanism of FIG. 11 illustrating actuation of the grapple jaws between an open configuration and a closed configuration according to an embodiment. [Figure 13B] 12 is a partially transparent perspective side view of the grapple jaws of the grapple mechanism of FIG. 11 illustrating actuation of the grapple jaws between an open configuration and a closed configuration according to an embodiment. [Figure 14A] FIG. 7 is a front perspective view of a socket drive mechanism of the end effector of FIGS. 6A-6B in a separated state. [Figure 14B] FIG. 14B is a side view of the socket drive mechanism of FIG. 14A. [Figure 14C] FIG. 14C is a cross-sectional side view of the socket drive mechanism of FIGS. 14A-14B, according to an embodiment. [Figure 15] FIG. 6 is a perspective view of the torque drive bolt of the prepared interface of FIG. 5 in a separated state. [Figure 16A] FIG. 15 is a front view of a socket profile of the socket head of the socket drive mechanism of FIGS. 14A-14C. [Figure 16B] 16 is a cross-sectional side view illustrating the handling of angular misalignment of the socket drive of the socket drive mechanism of FIGS. 14A-14C relative to the torque drive bolt of FIG. 15. FIG. [Figure 17A] FIG. 15 is a front perspective view of an Oldham coupling of the socket drive mechanism of FIGS. 14A to 14C. [Figure 17B] FIG. 17B is a front perspective exploded view of the Oldham coupling of FIG. 17A. [Figure 18] 17A-17B, illustrating addressing Oldham coupling misalignment, according to an embodiment. [Figure 19] 14A-14B, including a misaligned bolt and a fully seated bolt; [Figure 20] FIG. 20 is a cross-sectional side view of the socket drive mechanism of FIG. 19 illustrating axial compliance. [Figure 21A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-B, illustrating a microswitch sensing element location, according to an embodiment. [Figure 21B] 21B is a graphical representation of exemplary physical and electrical switch states for each of the socket engaged microswitch, payload present microswitch, rigidified load safety microswitch, and calibration microswitch of FIG. 21A; [Figure 22A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-B in a rest state for a powered-off state of the operating sequence. [Figure 22B] 22B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 22A. [Figure 23A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-B in a rest state for a power-on state of the operating sequence. [Figure 23B] 23B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 23A. [Figure 24A]FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B upon power-up while in a "rest state" state of the motion sequence. [Figure 24B] 24B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 24A. [Figure 25A] FIG. 7 is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-B in a calibration position in a motion sequence. [Figure 25B] 25B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 25A. [Figure 26A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-B ready for capture of a motion sequence. [Figure 26B] 26B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 26A. [Figure 27A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in the approach, ready to capture, portion of the operation sequence. [Figure 27B] 27B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 27A. [Figure 28A] 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in a payload-present state of an operating sequence. FIG. [Figure 28B] 28B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 28A. [Figure 29A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in the jaw closed (or "soft capture") state of the operating sequence. [Figure 29B] 29B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 29A. [Figure 30A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in an initial contact state with the socket drive in an operating sequence. [Figure 30B] 30B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 30A. [Figure 31A] 6A-6B are cross-sectional side views of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in a grapple fixture contact, socket misaligned state of the operating sequence. [Figure 31B]31B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 31A. [Figure 32A] 6A-6B in a rigidified, socket-unaligned state of the operation sequence. FIG. [Figure 32B] 32B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 32A. [Figure 33A] 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in a rigidified, socket aligned (ready for operation) state of the operation sequence. FIG. [Figure 33B] 33B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 33A. [Figure 34A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in a payload release state of an operating sequence. [Figure 34B] 34B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 34A. [Figure 35A]FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B at the release of the motion sequence and the beginning of pushing the probe. [Figure 35B] 35B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 35A. [Figure 36A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in a release of motion sequence, with the jaws beginning to open. [Figure 36B] 36B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 36A. [Figure 37A] FIG. 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in a release of motion sequence, with the jaws partially open. [Figure 37B] 37B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 37A. [Figure 38A] 6A-6B in a jaw-open position of an operating sequence. FIG. [Figure 38B] 38B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 38A. [Figure 39A] 6C is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-6B in a payload-released state of an operating sequence. FIG. [Figure 39B] 39B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 39A. [Figure 40A] FIG. 7 is a cross-sectional side view of the grapple mechanism and socket drive mechanism of the end effector of FIGS. 6A-B, returned to a rest state of the motion sequence. [Figure 40B] 40B is a graphical representation of the physical and electrical switch states for each of the socket engagement microswitch, the payload present microswitch, the rigidification safety microswitch, and the calibration microswitch corresponding to the operational states shown in FIG. 40A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Various devices or processes may be described below to provide examples of each claimed embodiment. The embodiments described below are not intended to limit any claimed embodiment, and any claimed embodiment may cover a process or device different from that described below. The claimed embodiments are not limited to a device or process having all of the features of any one device or process described below, or to features common to some or all of the devices described below.

[0021] Additionally, although process steps, method steps, algorithms, or the like may be described (in this disclosure and / or in the claims) in a sequential order, such processes, methods, and algorithms may be configured to work in alternative orders. In other words, any sequence or order of steps that may be described does not necessarily indicate a requirement that the steps be performed in that order. Steps of processes described herein may be performed in any order that is practical. Additionally, some steps may be performed simultaneously.

[0022] It will be readily apparent that when a single device or article is described herein, two or more devices / articles (whether they cooperate or not) can be used in place of the single device / article. Similarly, it will be readily apparent that when two or more devices or articles are described herein (whether they cooperate or not), a single device / article can be used in place of the two or more devices or articles.

[0023] The following relates generally to robotic systems and devices, and more specifically to a robotic interface for grappling and actuating a payload via a provisioned interface on the payload.

[0024] The development of low-mass active robotic interfaces that operate at the end of manipulators is a key element in the evolution of robotic on-orbit servicing, maintenance, and assembly capabilities. One objective is to minimize the mass and volume of a multipurpose end effector while simultaneously maximizing the load capacity of the design. The development of dexterous, multipurpose robotic interfaces can encourage spacecraft integrators to incorporate robot compatibility into future vehicles and architectures. Additionally, the robotics-based systems, methods, and devices described herein can be used in robotic applications outside the context of space-based systems while providing similar functionality and benefits.

[0025] As used herein, the term "end effector" generally refers to a robotic device or element at the end of a robotic arm that performs a function. As used herein, the term "end effector" includes devices that are permanently or inseparably attached to the end of a robotic arm and devices that have a separable interface with the end of the robotic arm. A separable interface can allow the end effector to be picked up, used, and put down (i.e., separated from the robotic arm). An instance of an end effector with a separable interface can also be referred to as a "tool" or an "end of arm tool." In such an instance, a robotic arm can have a first end effector attached to its end that has the functionality of a tool changer that allows the robotic arm to use multiple different tools, and a second end effector with a separable interface, where the second end effector can be engaged by the first end effector and function as a tool. In such an instance, the first "tool changer" end effector and the second "tool" end effector are each considered end effectors. Accordingly, references herein to "end effector" are intended to include all such devices as described in the foregoing unless otherwise specified.

[0026] The robotic capture system of the present disclosure can provide a relatively wide capture envelope for robotic motion and interface mating. Thus, the robotic capture system can advantageously provide forgiving misalignment during interface mating. Also, such forgivingness to interface misalignment can permit the use of a vision system with lower performance requirements for vision system alignment for capture. Thus, in some embodiments, the vision system used for alignment by the robotic capture system can be a vision system with lower performance requirements.

[0027] 1A-1D, a block diagram of a system 100 for robotic capture and manipulation of a payload is shown, according to an embodiment.

[0028] A system level view of system 100 is shown in Figure 1A. Certain components of system 100 are shown in more detail in Figures 1B-1D.

[0029] The system 100 includes a payload 102 and a robotic system 104 for capturing the payload 102 and for manipulating the payload 102 once captured.

[0030] The system 100 also includes a robotic workstation 106 for communicating with the robotic system 104. The robotic workstation 106 includes a human-machine interface for sending commands to the robotic system 104. Communication between the robotic workstation 106 and the robotic system 104 can be achieved via any suitable data transfer technique, such as a network connection (e.g., wireless or wired). The robotic workstation 106 and the robotic system 104 include communication interfaces and software to facilitate communication between the workstation 106 and the robotic system 104.

[0031] The payload 102 can be any object, and the nature of the payload 102 is not particularly limited other than being an object that a user of the robotic system 104 desires to be captured and manipulated (e.g., moved, actuated). For example, the payload 102 can be a tool that can be captured and then used by actuating the tool through the robotic system 104. Examples of payloads 102 in space-based applications of the system 100 include tools for capturing free-flyer objects and refueling tools.

[0032] The payload 102 includes a machine vision target 108 thereon. The machine vision target 108 can be a space vision marker system target in a space-based robotics implementation. The machine vision target 108 is disposed on the payload 102 such that a machine vision system 110 of the robotic system 104 can detect and track the machine vision target 108. The machine vision target 108 can include an encoding of data bits enabling that, when decoded by the machine vision system 110, identifies the payload 102. The machine vision system 110 is configured to assist with alignment for capture. Given that the end effector 116 can provide a relatively forgiving capture envelope, in some embodiments, the components of the machine vision system 110 responsible for alignment can be simplified and / or have lower performance requirements than might otherwise be required for a robotic capture task of a similar nature.

[0033] The machine vision system 110 is shown in more detail in FIG. 1B. The machine vision system 110 includes a camera subsystem 132 for visualizing the machine vision target 108, a processor for generating and processing image data collected by the camera subsystem, a memory for storing the image data, and a communication interface for communicating with other components of the robotic system 104 (e.g., communicating information about the detection and tracking of the machine vision target 108). The processor is configured to execute a recognition module 134. The recognition module 134 uses the image data provided by the camera subsystem 132 to identify the payload 102. The recognition module 134 references a target recognition database 136 stored in the memory to determine whether the processed machine vision target image data matches a given payload. The machine vision system 110 may also include an alignment module (not shown) for performing system alignment for capture. The alignment module (and the camera subsystem 132 used for vision above alignment) can be simplified (e.g., lower performance requirements) than conventional approaches to visual alignment tasks in robotic capture operations of a similar nature, particularly given the relatively wide capture envelope of the robotic system 104.

[0034] The camera subsystem 132 may include one or more cameras. The camera subsystem 132 may be configured to capture images of the machine vision targets 108 for work site registration and payload identification, image target fiducials (for photogrammetry measurements), and perform general inspection of the hardware. In some cases, the camera subsystem 132 may include a camera for machine vision target 108 viewing and a camera for imaging target fiducials for photogrammetry measurements. In some embodiments, the camera subsystem 132 may include a camera focused at a close distance and a camera focused at a mid-range. The close-range camera may be used for target 108 viewing and hardware inspection from a working distance, while the mid-range camera may be used for general inspection of the hardware and to image target fiducials (from a greater distance than the close-range camera). In one embodiment, the close-range camera can be mounted above the grapple subsystem 146 and / or the torquer subsystem 148, and the mid-range camera can be mounted to the side of the grapple subsystem 146 (e.g., substantially at the same height as the grapple subsystem 146). In one embodiment, the close-range camera is a boresight camera and the mid-range camera is a photogrammetry camera. The close-range camera can be configured and / or used to image machine vision targets 108 on the payload 102. The images can be used to extract a six degree-of-freedom (DOF) pose, which can allow for accurate positioning of the robotic system 104 with respect to the work site.

[0035] The robotic system 104 includes a robotic arm controller 112 for controlling the movement of the robotic arm 114. The robotic arm controller 112 includes a processor for processing data, a memory for storing data, and a communication interface for communicating with the machine vision system 110 and the robotic arm 114. For example, the robotic arm controller 112 can receive data from the machine vision system 110 regarding detection and tracking of the machine vision target 108 (and thus the payload 102) and generate arm movement commands based on the received machine vision data. The robotic arm controller 112 can then send the arm movement commands to the robotic arm 114 to control the movement of the robotic arm 114.

[0036] The robotic system 104 further includes a multipurpose end effector ("MEE") 116 connected to the robotic arm.

[0037] The MEE 116 is configured to capture (grapple and rigidify) the payload 102 via a grapple fixture 118 on the payload 102 .

[0038] The MEE 116 is further configured to actuate the payload 102 via a torque element 120 on the payload 102 .

[0039] The torque member or element 120 is connected to a torque drive subsystem 122 of the payload 102. Torque applied to the torque element 120 is transferred through the torque element 120 to the torque drive subsystem 122, driving the torque drive subsystem 122.

[0040] The grapple fixture 118 includes a coupling element 124 and a grapple probe 126 connected to the coupling element 124. The coupling element 124 can be attached to the payload 102 via a mounting surface. The grapple probe 126 extends from a connection end (not shown) that is used to connect the grapple probe 126 to the coupling element 124. The other end of the grapple probe 126 is a probe tip 128. The probe tip 128 can have a rounded outer surface. The probe tip 128 can be hemispherical in shape. The grapple probe 126 can be connected to the coupling element 124 such that the grapple probe 126 is substantially perpendicular to the mounting surface of the coupling element 124 in a rest state. In some cases, the grapple probe 126 may be deflectable (e.g., through attaching the probe 126 to the coupling element 124 via a deflectable joint (e.g., a spring, etc.).

[0041] In one embodiment, coupling element 124 can include a notched periphery for interlocking with a similarly notched component of end effector 116. The notches of the notched periphery are spaced apart from non-notched segments ("teeth" or "lobes") of the periphery.

[0042] Optionally, the payload 102 includes an electrical umbilical 130. The electrical umbilical 130 acts as an interface for the transfer of power and / or data from the end effector 104 to the payload 102. The electrical umbilical 130 can be connected to a power output system of the payload 102 to provide power to components of the payload 102 or to a data processing system of the payload 102 to receive and process data.

[0043] The machine vision target 108, torque member 120, grapple fixture 118, and electrical umbilical 130 comprise a prepared interface 138 of the payload 102. The prepared interface 138, when present on the payload 102, prepares the payload 102 for interfacing with (for capture and manipulation by) the end effector 116.

[0044] The MEE 116 includes an arm interface end 140 for interfacing with the robotic arm 114 and a payload interface end 142 for interfacing with the payload 102 .

[0045] The arm interface end 140 includes a robot arm interface 144 for connecting the end effector 116 to the robot arm 114 to enable manipulation of the end effector 116 by the robot arm 114. The robot arm interface 144 includes connections for transferring power, transferring data, and for actuating components of the end effector 116. The robot arm interface 144 also includes the physical connection of the robot arm 114 to the end effector 116.

[0046] The robotic arm interface 144 interfaces with various components of the payload interface end 142 to enable operation of the subsystems and mechanisms of the payload interface end 142 .

[0047] The payload interface end 142 includes a grapple subsystem 146 and a torquer subsystem 148. Optionally, the payload interface end 142 includes a power / data pass-through mechanism 149. The power / data pass-through mechanism 149 is configured to interface with an electrical umbilical 130 on the payload 102 and pass one or more of power or data to the payload 102. In some embodiments, the power / data pass-through mechanism 149 includes multiple umbilical assemblies. In certain embodiments, at least one umbilical assembly is disposed on each side of the grapple subsystem 146. The power / data pass-through mechanism 149 enables the end effector 116 to grapple a tool that requires a transfer of power and / or data.

[0048] The payload interface end 142 may include a refueling subsystem. The refueling subsystem may include a fuel coupling configured to interface or couple with a refueling receiving component (not shown) on the payload 102. The payload interface end 142 may also include a multi-purpose end effector embodiment with electrical pass-through and fluid pass-through valves that interface with the payload umbilical. The fluid may be a liquid or gas, including a pressurized fluid.

[0049] In some embodiments, the MEE 116 can include a mechanism for load limiting via sensed feedback. In an embodiment, the MEE 116 can include a force torque sensor (FTS). The FTS can be mounted internally. The FTS can be mounted to the main load path of the grapple subsystem 146 or the grapple mechanism (e.g., grapple mechanism 150 of FIG. 1C). The FTS can provide measurements of three axes of force and three axes of moment. In an embodiment, the FTS includes an FTS hardware frame that orients x and y laterally with z being axial. In general, soft capture (as described herein and shown, for example, in FIG. 29A) with low initial load by the MEE 116 places the interface in a state where the rigidification load can be precisely controlled. Soft capture corresponds to the probe tip 128 being captured by the grapple subsystem 146 (i.e., the grapple jaws 164 in FIG. 1C have closed onto and grappled the probe tip 128), but rigidification of the interface (as described herein) has not yet occurred. The FTS can be used to limit loads during grappling, payload handling, or payload attachment or removal from the interface to facilitate robotic motion.

[0050] The grapple subsystem 146 provides a means for grappling and rigidifying the robotic arm 114 to a hardware interface on the payload 102 via the grapple fixture 118. By grappling and rigidifying the interface between the end effector 116 and the payload 102, the grapple subsystem 146 enables subsequent manipulation of the payload by the end effector 116.

[0051] The grapple subsystem 146 is shown in greater detail in FIG. 1C.

[0052] The grapple subsystem 146 includes a grapple mechanism 150 for grappling and rigidifying a payload to the end effector interface, a grapple motor module 152 for driving the grapple mechanism 150, and a grapple mechanism state sensing subsystem 154 for performing state sensing in the grapple mechanism 150.

[0053] The sensing subsystem 154 generates output signals based on sensed state changes in the grapple mechanism 150 that are used to control the output of the grapple motor module 152 or other components.

[0054] The grapple mechanism 150 includes a probe receiving end 156 configured to receive the grapple probe 126 of the grapple fixture 118. The probe receiving end 156 includes a coupling element 158 ​​and a grapple opening 160 in the coupling element 158 ​​for receiving the grapple probe 126 therethrough for entry into the grapple mechanism 150.

[0055] The coupling element 158 ​​can have a concave surface for guiding the grapple probe 126 into the grapple opening 160. For example, the profile of the concave surface, the profile of the probe tip 128 of the grapple probe 126, and the relative motion of the payload 102 and the end effector 116 can work together to guide an off-center (in multiple translational and rotational axes) probe 126 (i.e., a probe 126 that is not precisely aligned with the opening 160) by forcing the probe tip 128 to slide along the concave surface of the coupling element 158 ​​toward and through the opening 160.

[0056] The coupling element 158 ​​is configured to mate with the coupling element 124 of the grapple fixture 118 when the coupling elements 158, 124 contact. The profile of the concave surface of the coupling element 158 ​​can complement the profile (e.g., concave and convex) of the mating surface of the coupling element 124. In embodiments in which the coupling element 124 of the grapple fixture 118 has a notched periphery, the coupling element 158 ​​also has a notched periphery. Generally, when mated, the teeth of the grapple fixture coupling element 158 ​​sit within and contact the notches of the end effector coupling element 158, and the teeth of the end effector coupling element 158 ​​sit within and contact the notches of the grapple fixture coupling element 124. In some cases, the notched periphery can include a curved surface to encourage the misaligned tooth-notch pair to slide into position where the tooth sits in the notch. As such, the coupling elements 124, 258 can promote alignment of the interface and provide improved resistance to torque along the long axis.

[0057] The grapple mechanism 150 further includes a jaw assembly 162. The jaw assembly 162 includes a grapple jaw 164 and a jaw actuator 166. The jaw actuator 166 is connected to the grapple jaw 164 and configured to move the grapple jaw 164 between an open configuration and a closed configuration. The grapple jaw 164 is configured to be actuated between an open configuration and a closed configuration (to allow entry of the grapple probe 126 into the throat of the jaw 164, and to grip and ultimately release the probe, respectively). In one embodiment, the grapple jaw 164 includes two jaw elements that form a jaw.

[0058] The grapple mechanism 150 further includes a jaw assembly translator 168 for translating the jaw assembly 162 in either direction (towards the payload interface end (“forward”) or away from the payload interface end (“reverse”)) along the capture axis of the grapple mechanism 150. The jaw assembly translator 168 is a translation mechanism driven by the grapple motor module 152. In one embodiment, the jaw assembly translator 168 can include a ball screw rotatable via the grapple motor module 152 and a ball nut, where the jaw assembly 162 is connected to the ball nut such that rotation of the ball screw causes the ball nut to translate the jaw assembly 162.

[0059] The jaw actuator 166 can be mechanically connected to a jaw assembly translator 168 such that retraction of the jaw assembly 162 past a particular position along the capture axis can cause the jaw actuator 166 to move the grapple jaws 164 from the open position to the closed position. Similarly, forward translation of the jaw assembly 168 past a particular position along the capture axis can cause the jaw actuator 166 to move the grapple jaws 164 from the closed configuration to the open configuration.

[0060] The grapple mechanism 150 also includes a compressible element 170 for compression to generate a target preload and to rigidify the interface between the grapple fixture 118 and the end effector 116. The compressible element 170 is then released or decompressed to release the preload (i.e., upon release of the grapple fixture). In one embodiment, the compressible element 170 includes one or more Belleville spring stacks or washers. The compressible element 170 is mounted in the main load path of the grapple mechanism 150. The Belleville stack has two seating surfaces. First, the screw sleeve begins to contact / compress the Belleville stack.

[0061] In one embodiment, the compressible element 170 can be mounted or otherwise positioned between a first compression surface of the jaw assembly translator 168 (at an end of the compressible element 170 proximal to the payload interface end) and a second compression surface of the jaw assembly 162 (at an end of the compressible element 170 distal to the payload interface end) such that the compressible element 170 is biased between the first and second compression surfaces. The jaw assembly translator 168 is configured to only retract the jaw assembly 162 to a certain point during capture and rigidification, after which point the jaw assembly translator 168 continues to retract along the capture axis. This continued retraction compresses the compressible element 170 between the first and second compression surfaces because the first surface is retracted and the second surface is stationary. The amount of retraction can be measured (e.g., via state sensing subsystem 154) and the retraction can be stopped when a target preload of compressible element 170 is generated. In some cases, multiple target preloads may be possible through different degrees of retraction and compression of compressible element 170.

[0062] The jaw assembly 162 is part of the "moving component" of the grapple mechanism 150, which translates along the capture axis of the grapple mechanism 150 during retraction and release. The moving component also includes one or more components of a jaw assembly translator 168 that translates along the capture axis during retraction and release, including a first compression surface used to compress the compressible element 170. For example, in one embodiment, the moving component can include the jaw assembly 162 as well as a ball nut and screw sleeve, which are part of the jaw translator mechanism 168. The first compression surface used to compress the compressible element 170 can be a surface that faces the arm interface end of the screw sleeve.

[0063] The grapple mechanism status sensing subsystem 146 includes a probe presence sensor 172 and a translational position tracking sensor 174 for calibration.

[0064] The probe presence sensor 172 is used to detect when the grapple probe 126 enters the grappling area between the grapple jaws 164. The probe presence sensor 172 may be disposed at a distal end of the grappling area such that in order to trigger the payload presence sensor 172, the probe tip 128 of the grapple probe 126 must enter the grappling area and be in position for grappling by the jaws 164.

[0065] Any suitable type of sensor may be used as the payload presence sensor 172. In one embodiment, the payload presence sensor 172 includes a physical contact sensor that registers a change in state when the sensor is contacted by the probe tip 128.

[0066] The state change registered by the payload presence sensor 172 is used as an indicator to actuate the grapple jaws 164 closed using the jaw actuator 166 .

[0067] The translational position tracking sensor 174 is used for calibration to detect when the jaw assembly 162 leaves a calibration or home position during retraction. For example, the sensor 174 can have a first state when the jaw assembly 162 is in the home position and a second state when the jaw assembly 162 is not in the home position. The sensor 174 can include a physical switch that is engaged / disengaged when the jaw assembly 162 is translated from the home position. The sensor 174 registers a state change. The state change is communicated to a position tracking device (e.g., a resolver, etc.), which tracks or calculates the displacement along the capture axis relative to the home position. The position tracking device can be a component of the grapple motor module 152. The position tracking device is configured to generate a signal when a pre-determined displacement (a "target preload position") is achieved and to output the signal to the motor to stop the motor and arrest the translation. In one embodiment, a position tracking device is able to track motor turns and determine when a target position has been reached.

[0068] An exemplary sequence of operation of the grapple subsystem 146 will now be described. As the end effector 116 is moved towards the grapple fixture 118 on the payload 102, the grapple probe enters the grapple mechanism 150 through an opening 160 in the probe receiving end 156. The grapple probe 126 continues to move into the grapple mechanism 150 such that the probe tip 128 enters the grappling area between the open grapple jaws 164. In doing so, the probe tip 128 triggers a state change in the probe presence sensor 172. A signal indicative of the state change is output to the grapple motor module 152. Upon receiving the signal, the grapple motor module 152 drives the jaw assembly translator 168 to retract the jaw assembly 162 along the capture axis. Initial retraction of the jaw assembly 162 causes the jaw actuator 166 to move the grapple jaws 164 to a closed position to grapple the probe tip 128. As the jaw assembly 162 is retracted by the jaw assembly translator 168, the grapple probe 126 is also retracted, drawing the coupling element 128 on the payload 102 towards the coupling element 158 ​​of the end effector 116.

[0069] As the jaw assembly 162 is retracted from the home position, the translation position tracking sensor 174 is triggered by the movement of the jaw assembly 162 and registers a state change. A signal indicative of the state change is output to the position tracking device which begins tracking the position. The position tracking device outputs a stop signal to the grapple motor module 152 when the target preload position is reached. Upon receiving the stop signal, the motor stops driving the jaw assembly translator 168.

[0070] The target preload position is a position where the coupling elements 128, 158 of the grapple fixture 118 and end effector 116, respectively, are in mating contact and the compressible element 170 is compressed, as described above. Thus, the target preload position can include retraction by the jaw assembly translator 168 beyond a point where the jaw assembly 162 is no longer retracted or capable of being retracted to compress the compressible element 170 between a compression surface of the jaw assembly translator 168 and a compression surface of the jaw assembly translator 168.

[0071] Referring again to FIG. 1A, the torquer subsystem 148 is shown in greater detail in FIG. 1D.

[0072] The torquer subsystem 148 includes a torquer mechanism 176 for applying torque to the torque element 120 on the payload 102, a torquer motor module 178 for driving the torquer mechanism 176, and a torquer mechanism state sensing subsystem 180 for sensing state changes in the torquer mechanism 176 and for outputting signals to the torquer motor module 178 to modify the output of the motor module 178.

[0073] The torquer mechanism 176 includes a torquer seating element 182 (e.g., a socket head) for receiving and seating the torque element 120 when the end effector 116 moves closer to the payload 102 (e.g., during capture by the grapple subsystem 146).

[0074] The torquer mechanism 176 further includes a seating element rotator 184 for rotating the seating element to apply torque to the seated torque bolt 120. The seating element rotator 184 can also be used to rotate and properly align the seating element 182 when the seating element 182 is misaligned with the torque element 120. The seating element rotator 184 is driven by the torque motor module 178.

[0075] The torquer mechanism 176 further includes an axial compliance mechanism 186. The axial compliance mechanism 186 is used to passively back off the torquer seating element 182 from the torque element 120 upon misaligned contact between the torque element 120 and the seating element 182. In one embodiment, the axial compliance is achieved through a spring-loaded torquer seating element 182 (wherein the misaligned contact compresses the spring, causing backoff).

[0076] The torquer mechanism status sensing subsystem 180 includes a seating element engaging sensor 188 that is used to sense and register a change in state between when the seating element 182 is properly aligned / seated on the torque element 120 and when the seating element 182 is misaligned / not seated on the torque element 120. For example, the sensor 188 can have a first state when the seating element 182 is in a forward position and a second state when the seating element 182 is retracted from the forward position (i.e., the axial compliance mechanism 186 is engaged). In one embodiment, the sensor 188 can include a switch that is positioned such that the seating element 182 engages the switch when the seating element 182 is forward and disengages the switch when the seating element 182 is retracted (or vice versa).

[0077] Based on the sensed state change indicative of misalignment (via retraction from a forward position), the torquer motor module 178 drives the seating element rotator 184 to rotate the seating element 182 to properly seat on the torquer element 120. The rotation of the seating element 182 can be commanded automatically in the robotic system 104 or can be commanded by the robotic workstation 106 (e.g., an operator commands the rotation of the seating element 182 until properly seated). When the torquer element 120 is properly seated, the seating element 182 returns to the forward position (the axial compliance mechanism 186 is no longer engaged) and the seating element engagement sensor 188 senses and registers the state change. A signal indicative of the state change is output to the torquer motor module 178. In response to the received signal, the torquer motor module 178 drives the seating element rotator 184 to rotate the torquer seating element 182. Rotation of the seating element rotates the seated torque element 120, thereby transmitting torque to the torque element 120, which transmits the applied torque to the payload torque-driven subsystem 122.

[0078] The seating element rotator 184 can be configured to apply a desired amount of torque (eg, through counting rotations).

[0079] Referring now to FIG. 2, a method 200 for robotic capture and manipulation of a payload is shown, according to an embodiment.

[0080] Method 200 can be implemented using system 100 of Figure 1. In describing method 200, explicit reference may be made to components of system 100 of Figure 1 as examples of components that perform particular functions or steps. In other instances, explicit reference may not be made to components of system 100, but it is understood that components of system 100 can be used or configured to perform particular functions or steps, even if not explicitly mentioned.

[0081] At 202, a payload interface end of the end effector is moved via the robotic arm toward a prepared interface on the payload. The prepared interface includes a grapple fixture and a torque element. The end effector is moved by the robotic arm toward the prepared interface such that a grapple probe of the grapple fixture is within the capture envelope of the end effector.

[0082] At 204, the grapple probe is grappled by a grappling mechanism of the end effector.

[0083] At 206, the grappled grapple probe is retracted along the capture axis of the end effector, bringing the coupling element and torque element of the grapple fixture into contact with the payload interface end of the end effector.

[0084] At 208, the coupling element of the grapple fixture is mated with the coupling element at the front end of the grapple mechanism by continued movement of the respective coupling elements toward each other through retraction of the grapple probe which is connected to the coupling element of the grapple fixture.

[0085] At 210, the grapple fixture is rigidified to the end effector by retracting the grapple mechanism to the target preload.

[0086] At 212, a torque element is seated at the payload interface end of the end effector within a seating element of the torquer mechanism of the end effector.

[0087] At 214, torque is applied to the seated torque element by rotating the torquer seating element to transmit the torque to the torque drive subsystem of the payload. The torque element is connected to the torque drive subsystem in the payload such that transmission of torque to the torque element through its rotation by the seating element is transmittable to the torque drive subsystem to drive the torque drive subsystem.

[0088] At 216, the preload created at 110 is released by the grapple mechanism.

[0089] At 218, the grapple mechanism pushes the grapple probe along the capture axis in a direction opposite to the retraction, ejecting the grapple probe from the grapple mechanism.

[0090] The grapple probe is released from the grapple mechanism at 220. Releasing the grapple probe enables the release of the grapple fixture (and thus the payload) from the end effector.

[0091] 3A and 3B, a method 300 of robotic capture of a payload using an end effector is shown, according to an embodiment.

[0092] Method 300 can be implemented using system 100 of Figure 1. In describing method 300, explicit reference may be made to components of system 100 of Figure 1 as examples of components that perform particular functions or steps. In other instances, explicit reference may not be made to components of system 100, but it is understood that components of system 100 can be used or configured to perform particular functions or steps, even if not explicitly mentioned.

[0093] The method 300 can be used to grapple and rigidify a captured payload to an end effector to allow for subsequent manipulation or actuation of the payload.

[0094] In one example, the method 300 may be used in a space-based application, where the payload is a tool (eg, a free flyer capture tool or a refueling tool, etc.).

[0095] At 302, a grapple mechanism of the end effector is moved via the robotic arm towards a grapple fixture above the payload such that a grapple probe of the grapple fixture is within the capture envelope of the end effector.

[0096] Movement commands for the robotic arm are received from a robotic arm controller connected to the robotic arm. The movement commands can be generated at a robotic workstation and communicated to the robotic arm controller. In space-based applications, the robotic workstation can be on the ground or at another remote location.

[0097] At 304, the grapple probe of the payload is guided through continued motion of the end effector into a grappling area toward the payload.

[0098] The grapple area is disposed between the grapple jaws of the grapple mechanism such that when the grapple jaws are actuated to close, the grapple jaws grapple the grapple probe. Guiding the grapple probe into the grapple area can include guiding a probe end of the grapple probe toward and into the grapple area via a probe guide surface ("grapple surface") having a concave profile disposed at the payload interface end of the end effector. The grapple surface can include an opening centrally disposed in the probe guide surface, toward and through which the grapple probe is guided by the concave profile of the surface and the continued motion of the end effector toward the payload. Guiding the grapple probe by the grapple surface through the opening into the grapple area can also constrain the grapple probe in a position generally parallel to a capture axis along which the grapple probe will be retracted during capture.

[0099] At 306, the end effector senses that the grapple probe has entered the grappling area.

[0100] This may include, for example, triggering a sensing element located in or near the grappling area such that the sensing element is triggered by the grapple probe only when the grapple probe is in the grappling area. In an embodiment, this may be accomplished by placing a sensing element at the distal end of the grappling area that is triggerable by physical contact with the probe end of the grapple probe (e.g., depressing the sensing element). The sensing includes generating a state change signal that reflects a state change (payload present, grapple probe in the grappling area). The state change signal may then be communicated to one or more other components of the grapple mechanism to effectuate a subsequent action based on the current state (payload present).

[0101] At 308, translation of the grapple mechanism along the capture axis in a direction away from the payload interface end ("reverse") is initiated in response to sensing the presence of the grapple probe in the grappling area at 206.

[0102] The state change signal generated at 306 is sent to and received by the translation mechanism, which initiates retraction upon receiving the state change signal. In one embodiment, the state change signal can be communicated to a grapple motor module. In response to receiving the state change signal, a motor component of the grapple motor module drives the translation mechanism to retract the grapple mechanism. This can include, for example, driving rotation of a ball screw, causing a ball nut to retract along the ball screw, and moving the grapple mechanism (or a component thereof) through a connection to the ball nut.

[0103] At 310, the grapple jaws are actuated to close (move from an open state to a closed state) through the initial retraction of the grapple mechanism at 208.

[0104] For example, initial retraction of the grapple mechanism can cause a jaw actuation component of the grapple mechanism to mechanically actuate the grapple jaws to close through a mechanical link or connection to the translation mechanism. A spring is connected to the probe presence bar. A pair of springs maintain a payload presence switch activated during mechanism retraction.

[0105] At 312, the grapple mechanism (grappling the grappled probe) is retracted along the capture axis to a target preload position, which may be pre-calibrated.

[0106] At 314, a coupling element of the grapple fixture is mated with a coupling element of a grapple mechanism disposed at the payload interface end of the end effector through retraction of the grapple mechanism.

[0107] The coupling element can be a component of a grapple surface of the end effector, for example, the grapple surface can act as both a probe guide surface and a coupling element.

[0108] Generally, the grapple fixture coupling element is attached to the payload and acts as the base component for the grapple fixture, and the end effector coupling element is at the payload interface end such that retraction of the grapple probe along the capture axis brings the coupling elements together in contact.

[0109] The engagement of the respective coupling elements can be used to drive alignment of the interface between the grapple fixture and the end effector (eg, in the event of positional misalignment of the grapple interface).

[0110] Also, mating coupling elements can improve overall composite load capacity (eg, stiffer interface when picking up a payload).

[0111] The engagement of the coupling elements can limit or eliminate rotational play about the roll axis at the end effector and grapple fixture interface. The engagement of the coupling elements can make the grapple interface stronger with respect to torque about the long axis.

[0112] At 316, a compressible element disposed in the primary load path of the grapple mechanism is compressed to the target preload through retraction of the grapple mechanism to the target preload position.

[0113] The compressible element can be a Belleville spring stack, etc. Compressing the compressible element achieves the target preload and rigidifies the interface between the grapple fixture and the end effector.

[0114] At 318, the end effector senses that the grapple mechanism has reached a target preload position based on the tracked displacement of the grapple mechanism along the capture axis from the calibration position.

[0115] This may include, for example, sensing when the grapple mechanism leaves a calibration position, generating a state change signal in response to leaving the calibration position, communicating the state change signal to a position monitoring component, monitoring displacement of the grapple mechanism along the capture axis from the calibration position via the position monitoring component, and generating a state change signal when the position monitoring component identifies that a target preload position has been reached.

[0116] At 320, retraction of the grapple mechanism along the capture axis is stopped in response to sensing that the target preload position has been reached at 318.

[0117] This may include, for example, the translation mechanism receiving a state change signal generated by sensing at 318 and stopping retraction of the grapple mechanism. In one embodiment, this may include the state change signal being communicated to a motor which, in response to receiving the signal, stops driving rotation of a ball screw used to translate the grapple mechanism.

[0118] At this stage, the payload is rigidified to the end effector through the grapple fixture. The payload can be manipulated by the end effector. Manipulation can include, for example, steering the payload (through commanded movement of a robotic arm to which the end effector is connected), actuating the payload (e.g., transmitting torque through a torque application interface on the payload to actuate a torque-driven subsystem of the payload), or passing power, fuel, and / or data from the end effector to the payload through an electrical umbilical interface.

[0119] The steps that follow relate to the release of the captured and rigidified payload through steps 302-320. Release is initiated via a command from the robotic workstation 106 to the robotic arm controller 112, to the robotic arm 114, to the MEE (which powers the actuators in the direction for release), etc. Some embodiments may include an external means of reversing the grapple mechanism, such as an EVA release by an astronaut or an equivalent external robotic system action.

[0120] At 322, the preload created at 316 is released by releasing (decompressing) the compressible element through forward movement (i.e., translation opposite to the direction of retraction) of the grapple mechanism along the capture axis.

[0121] At 324, the grapple mechanism pushes the grapple probe along the capture axis toward the payload interface end. This is accomplished through continued translation of the grapple mechanism in a forward direction.

[0122] At 326, the grapple jaws are actuated to open through forward movement of the grapple mechanism along the capture axis to allow release of the grapple probe. This can be accomplished through the jaw actuation components described at 310 (operating in the opposite direction, moving from a closed state to an open state).

[0123] At 328, the grapple fixture is released from the grapple mechanism and the payload is released from the end effector.

[0124] Referring now to FIG. 4, a method 400 for robotically actuating a payload via an end effector is illustrated, according to an embodiment.

[0125] The payload can be a tool, and the method 400 can be used to actuate the tool to enable a robotic capability. The method 400 can be implemented using the system 100 of FIG. 1. In describing the method 400, explicit references may be made to components of the system 100 of FIG. 1 as examples of components that perform particular functions or steps. In other instances, explicit references may not be made to components of the system 100, but it is understood that components of the system 100 can be used or configured to perform particular functions or steps, even though not explicitly mentioned.

[0126] At 402, a torque mechanism at the payload interface end of the end effector is moved, via a robotic arm connected to the end effector, towards a torque element on the payload.

[0127] In general, the torque element is configured to have a torque applied to it and to transmit the applied torque to a torque-driven subsystem of the payload. In some cases, the movement at 402 can be part of a payload capture sequence, for example, as illustrated in FIG. 2. For example, the end effector can move toward the payload due, at least in part, to the end effector performing a capture and rigidification process that brings the payload (and the torque element) closer to the payload interface end of the end effector.

[0128] The torque mechanism is brought into contact with the torque element. The torque element on the payload may or may not be properly aligned with the torquer seating element. Proper alignment facilitates seating of the torque element in the torquer seating element. The torquer seating element is configured to mate with the torque element (e.g., complementary profile). The torquer seating element is rotatable by operation of the torquer mechanism to transmit torque to the seated torque element.

[0129] At 404, the torquer mechanism passively retracts axially when the misaligned torque element and torquer seating element come into contact.

[0130] This can occur, for example, via compression of a spring component in the torquer mechanism. For example, the torquer mechanism can include a spring-loaded component (e.g., a socket head) that includes a torquer seating element. Passive axial retraction can prevent the torquer seating element from continuing to move toward the torque element in cases where the torque element is misaligned (as the payload interface end of the end effector continues to move toward the payload).

[0131] At 406, axial retraction of the torquer mechanism is sensed by the end effector.

[0132] This can be achieved, for example, by using a sensing element that is configured to register a state change when the torquer mechanism is displaced from a forward ("home") position.

[0133] For example, axial retraction of the torquer mechanism can cause the torquer mechanism to engage (or disengage) a switch or other sensing element and register a state change. The state change is indicative that the torque element is not properly aligned / seated in the torquer seating element. The sensed state change can then be communicated to allow steps to be taken to properly seat the torque element.

[0134] At 408 , the torquer mechanism is rotated based on the sensed axial retraction of the torquer mechanism from 406 .

[0135] The torquer mechanism is rotated until the torquer seating element is properly seated on the torque element.

[0136] In one embodiment, the rotation of the torquer mechanism can be commanded by a human operator through a human-machine interface configured to generate commands based on input from a user and to send the commands to a robotic system of which the end effector is a component. For example, a command can be sent from a robot workstation (operator) to a robotic arm controller, which commands the robotic arm to cause the end effector to rotate the torquer mechanism.

[0137] In another embodiment, rotation of the torquer mechanism can be performed automatically by the end effector without human user input.

[0138] When the torque element is properly aligned and seated in the torquer seating element, the axial compliance in the torquer mechanism is released, causing the torquer mechanism to move forward to its home position. In embodiments using a spring component, the compression force on the spring is removed and the spring component returns to its uncompressed state, causing the torquer mechanism to move axially forward.

[0139] At 410, the end effector senses that the torquer seating element is properly seated on the torque element.

[0140] This may include, for example, registering a state change in the sensing element described in 406 when the torquer mechanism returns to the forward home position. For example, forward axial movement of the torquer mechanism may cause the torquer mechanism to disengage (or engage) a switch or other sensing element, registering a state change. The state change indicates that the torquer element is properly aligned / seated within the torquer seating element. The sensed state change may then be communicated to initiate an action (i.e., actuation) using the torquer mechanism.

[0141] At 412, the torquer mechanism is rotated to apply torque to the seated torque element in response to sensing that the torquer seating element is properly seated on the torque element at 410.

[0142] This can be achieved, for example, by communicating a state change signal from a sensing element to a torquer motor that is configured to initiate rotation of a torquer mechanism upon receiving the state change signal.

[0143] Rotation of the torque element on the payload by the torquer mechanism transmits torque through the torque element to a torque-driven subsystem of the payload connected to the torque element, which enables actuation of the torque-driven subsystem of the payload to perform one or more functions (e.g., tooling functions).

[0144] At 414, the torque applied to the torque element by the torquer mechanism is measured by the torquer mechanism.

[0145] This may include, for example, monitoring the number of turns of the torquer seating element (e.g., up to a desired or predetermined number) or the amount of torque applied (e.g., via current limiting). The torquer mechanism may include a resolver for rotational position monitoring.

[0146] At 416, the torquer mechanism stops rotation of the torquer seating element when a desired torque is applied to the torque element.

[0147] Reference is now made to Figures 5 through 20, which illustrate an embodiment of a robotics-based system of the present disclosure, which is an example of system 100 of Figure 1 and which may be used to implement any one or more of the methods of Figures 2 through 4. The embodiment is designed for space-based robotics applications (e.g., on-orbit robotic servicing of payloads, etc.), but may also be used (with or without modifications, as appropriate) in non-space-based applications.

[0148] Referring now to FIG. 5, a system 500 for robotic capture and actuation of a payload is shown, according to an embodiment.

[0149] The system 500 includes an end effector (EE) 502 for interfacing with a prepared interface 504. The prepared interface 504 is on a payload 516. The payload 516 can be a spacecraft or other hardware (e.g., a specialized tool (e.g., a free flyer capture tool, a refueling tool), etc.). By interfacing with the payload 516 through the prepared interface 504, the end effector 502 can grapple and actuate the payload 516.

[0150] The EE 502 includes a payload interface end 506 for interfacing with a payload 516 via a provisioned interface 504, and an arm interface end 507 for connecting the EE 502 to a robotic manipulator (e.g., a robotic arm).

[0151] Typically, during interfacing, a robotic manipulator is used to move the payload interface end 506 of the EE 502 towards a prepared interface 504 on the payload 516. In some cases, the arm interface end 507 can be used in a host-EE interface, where the host is the operator of the robotic system and the robot arm and end effector are part of the robotic system, and the payload interface end 506 can be used in an EE-user interface, where the user is the payload 516 owner (or otherwise in control of the payload 516) and wishes to utilize the services of the host / operator in manipulating the payload 516. This can provide a walking arm embodiment, as described below.

[0152] The prepared interface 504 includes a machine vision target 522. The machine vision target 522 is disposed on a first surface 526 of the payload 516. The machine vision target 522 allows for visualization of the payload 516. In some cases, the machine vision target 522 can allow for identification of the payload 516. By identifying the payload 516 as being of a particular class (e.g., a particular type of tool), the EE 502 can be instructed to interface with the payload 516 based on the identity of the payload 516.

[0153] The prepared interface 504 includes a torque element 524. The torque element 524 may also be referred to as a torque bolt or an actuation member. The torque element 524 is disposed on a second surface 528 of the payload 516.

[0154] The torque element 524 in the embodiment of FIG. 5 is a ball end hex bolt (eg, 7 / 16"). In other embodiments, the torque element 524 can have other shapes or configurations.

[0155] Torque element 524 connects to a torque driven subsystem (not shown) of payload 516. Torque element 524 enables actuation of payload 516 through torque element 524. Among other things, torque element 524 enables acceptance and transmission of torque to the torque driven subsystem, thereby driving the torque driven subsystem. By doing so, the torque driven subsystem can be driven through torque generated external to payload 516.

[0156] The prepared interface 504 includes a grapple fixture 508 .

[0157] The grapple fixture 508 is disposed on a second surface 528 of the payload 516. The grapple fixture 508 includes a coupling element 514 and a grapple probe 512 (or probe 512). The coupling element 514 is attached to the second surface 528 of the payload 516. The grapple fixture 508 enables capture of the payload 516. Among other things, the grapple fixture 508 enables grappling and rigidification of the payload 516 via the grapple probe 512 and the coupling element 514.

[0158] The payload 516 to which the prepared interface 504 is attached may be considered a "prepared element" or "prepared asset," where the payload 516 is pre-"prepared" with the prepared interface 504, allowing the EE 502 to interact with the payload 516. In some cases, the prepared interface 504 may be a standardized interface that may be provided on various payloads to simplify implementation of the system 500.

[0159] The vertical layout of the current flight system can improve packaging and volume / mass determination for torquer and camera placement relative to the end effector and can provide improved payload packaging and assembly needs for the mission. Other layouts can be provided to integrate with different system solutions on the payload side.

[0160] The target and grapple fixture can have their normal vectors in the same direction and can be aligned with the camera optical axis and end effector axis, respectively (an offset of about 20° in pitch / yaw can be tolerable but should be avoided). The target and grapple fixture can be in close proximity to minimize calibration complexity and thermal distortion effects.

[0161] The grapple fixture and torque bolt can have their normal vectors in the same direction to minimize initial alignment issues prior to extension of the torque. Embodiments include when the torque is pitched / yawed 90° relative to the grapple fixture axis. The grapple fixture and torque bolt can be in close proximity to minimize alignment issues, load path length, and thermal distortion effects.

[0162] The EE 502 includes a camera subsystem 518 at the payload interface end 506 for visualizing a machine vision target 522 .

[0163] The camera subsystem 518 can generate image data of the machine vision target 522 that can be processed by a processing device (which can be located in the EE 502 or in a robotic arm to which the EE 502 is connected) to identify or determine the position and orientation of the payload 516. The camera subsystem 518 can be used for target viewing or work site inspection. The camera subsystem 518 can provide the system operator with images for pose estimation and situational awareness to support precise robot alignment / positioning control. The EE 502 provides a means for inspecting on-orbit assets via the camera subsystem 518. The system can include another camera application for photogrammetry.

[0164] The EE 502 includes a socket drive mechanism 520 at the payload interface end 506 .

[0165] The socket drive mechanism 520 is configured to interface with a torque element 524 of the prepared interface 504. The socket drive mechanism 520 seats and actuates the torque element 524 and transmits torque thereto, which can be passed to a torque driven subsystem of the payload 516.

[0166] The socket drive mechanism 520 can act as a torque pass-through mechanism to actuate the torque element 524 as well as other tools and / or mechanisms. The socket drive mechanism 520 provides clockwise (CW) and counterclockwise (CCW) rotational capability over a continuous range of motion. Rotational capability can be provided (via current limiting) for a desired number of turns or until a desired torque is achieved. Thus, if the payload 516 is or includes a special purpose tool (e.g., a free flyer capture tool, a refueling tool, etc.), the socket drive mechanism 520 can be used to actuate the special purpose tool.

[0167] The EE includes a grapple mechanism 510 at the payload interface end 506 .

[0168] The grapple mechanism 510 is configured to receive, grapple, and rigidify the grapple fixture 508 via the grapple probe 512 and the coupling element 514. The grapple mechanism 510 of the EE 502 provides a means to grapple, capture, and rigidify a specialized tool (i.e., a payload 516). By doing so, the grapple mechanism 510 enables the EE 502 to perform a pick-and-place operation of a prepared element (i.e., a payload 516 having a prepared interface 504) through grapple, capture, and rigidification.

[0169] The grapple mechanism 510 provides a means for grappling and rigidifying hardware, such as a payload or tool equipped with the grapple fixture 508. When rigidified, both halves of the interface are engaged together and transmit static loads between them without separation of the interface, up to the maximum rigidification load capacity of the EE 502. The grapple mechanism 510 provides a means for grappling and rigidifying a robotic arm (not shown) to a hardware interface using the grapple fixture 508.

[0170] The EE502 can be used to steer both large and small payloads. The EE502 can act as an anchor for the walking arm. The EE502 can be used to manipulate fasteners on the payload 516 or other hardware.

[0171] The system 500 can be controlled from the ground, and automated operations are enabled from the ground, controlled via on-board arm control software.

[0172] In variations, the EE502 may serve as a mechanical, electrical, data, and / or viewing interface between the robotic arm and an attached payload (e.g., payload 516) or base structure (in the case of an end-over-end walking arm). Specific EE502 functions may include grappling the grapple fixture 508, seating and applying torque to the torque element 524, acting as a conduit for power and data via an umbilical mechanism (not shown) (e.g., to facilitate the end-over-end arm walking or interfacing to a tool / payload requiring power and / or data), and viewing functions for various operations (e.g., visual inspection, refueling) via a camera subsystem 518. Note that interface load capacity may be affected by which modular subassemblies are included (e.g., an EE502 that includes umbilical mechanisms may be able to maintain a higher fully engaged preload than an EE502 that does not include them).

[0173] The EE502 can be used to steer payloads via capture and release of fixed payloads / tools. The EE502 can be used to perform capture and release of free-flying (FF) payloads with FF capture / release tools. The EE502 can be used to perform release of FF payloads from FF capture / release tools. The EE502 can further include functionality for reacting loads at the arm base for the case of a walking arm where the EE502 can be used to anchor the robotic arm to a structure.

[0174] In certain embodiments, the EE502 is configured to interface with a capture / release tool equipped with a grapple fixture 508, which is configured to capture and rigidify a free-flying payload. For example, the socket drive mechanism 520 of the EE502 can drive the rigidification mechanism of the tool (including an umbilical between the EE502 and the tool). A motor in the tool can drive a latch on the tool side of the interface. The EE502 can grapple the FF capture tool and mate with an umbilical (not shown). The tool's latch motor can be actuated through the umbilical, and the latch engages on a load reaction feature on the EE502 side.

[0175] 6A and 6B, the end effector 502 of the system 500 of FIG. 5 is shown in isolation.

[0176] The camera subsystem 518 includes first and second boresight cameras 519a, 519b (collectively referred to as boresight cameras 519 and generally referred to as boresight cameras 519).

[0177] The first and second boresight cameras 519a, 519b can function as primary and redundant boresight cameras to provide redundant views (to provide operational fault tolerance). The boresight camera 519 is used to view a machine vision target 522 on the prepared interface 504 during operation for alignment (e.g., using a pose estimation algorithm). The boresight camera 519 supports automation by capturing an image of the machine vision target 522 for work site registration. This can be a key part of automated operation in terms of the ability to view something at the work site that allows the system to become registered with the work site during operation. Six degree of freedom (6DOF) poses can be extracted from the images acquired by the boresight camera 519. The 6DOF poses can enable an operator to command the robotic system to accurately position itself relative to the work site. The 6DOF poses can be extracted from either of the redundant views.

[0178] The boresight camera 519 can be used to inspect the hardware from a working distance, which can range from high hover to low hover.

[0179] In some cases, the boresight camera 519 is capable of providing a black and white image.

[0180] The camera subsystem 518 also includes a photogrammetry camera 521.

[0181] The photogrammetry camera 521 is configured to image target fiducials for photogrammetry measurements. The camera 521 (photogrammetry camera) can also be used for general inspection of hardware. The camera 521 can enable inspection from a distance farther away from the target than that provided by the boresight camera 519. The camera 521 also has a suitable working distance for performing hardware inspection (from a distance farther away than using the boresight camera). The photogrammetry camera 521 can provide black and white images.

[0182] In one embodiment, the boresight camera 519 is focused at a close distance and the photogrammetry camera 521 is focused at a mid-range distance. In one embodiment, all three cameras 519a, 519b, and 521 can be the same, but with lenses focused at different distances and with different f-stops depending on the function.

[0183] Each camera assembly 519, 521 can be paired with a light emitting diode (LED) ring (not shown) for illumination. In one embodiment, the boresight camera 519 is equipped with red LEDs and the photogrammetry camera 521 is equipped with white LEDs (not shown).

[0184] Cameras 519, 521 are mounted on the EE 502 to provide opportunities for inspection and situational awareness, as well as to view targets or other visual markers (fiducials) as required during operation. In some embodiments, the EE 502 can include one or more electrical umbilical assembly mechanisms for passing power or data to a payload. The umbilical assembly mechanisms are configured to interface (e.g., couple or mate) with a receiving component on the payload (e.g., electrical umbilical 130). The umbilical mechanisms can be located on the left or right side of the grapple mechanism 510. In some embodiments, the camera 521 can be replaced with an umbilical assembly (i.e., an umbilical assembly mounted in substantially the same position as the camera 521).

[0185] The grapple mechanism 510 is implemented as a grapple canister 528. The grapple canister houses the various components of the grapple mechanism 510.

[0186] Disposed at the payload interface end 506 of the grapple canister 528 is a front end of a grapple mechanism 510 that includes a coupling element 532. The coupling element 532 of the grapple mechanism 510 is configured to interface and mate with a coupling element 514 of a grapple fixture 508 on a payload 516.

[0187] Coupling element 532 includes a concave surface 530 and a generally circular opening 534 (grapple opening) centrally disposed on concave surface 530. Concave surface 530 is used to guide probe 512 of grapple fixture 508 toward and through opening 534 and into grapple canister 528. Concave surface 530 also has a profile generally complementary to the convex profile of coupling element 514 of grapple fixture 508, which promotes mating of coupling elements 514, 532 during capture.

[0188] The socket drive mechanism 520 of the EE 502 includes a socket drive 536 (or socket head 536). The socket drive 536 includes a socket 538 centrally disposed at the payload interface end 506 of the socket drive 536. The socket 538 is configured to receive and seat the torque element 524 of the prepared interface 504 when the grapple mechanism 510 grapples and rigidifies the payload 516 via the grapple fixture 508. The socket head 536 can contact the second surface 528 when the socket drive mechanism applies torque to the prepared interface 504 via the torque element 524.

[0189] The grapple mechanism 510 and the socket drive mechanism 520 are disposed perpendicular to one another such that, upon capture, the grapple mechanism 510 and the socket drive mechanism 520 are aligned with the grapple fixture 508 and the torque element 524, respectively.

[0190] The EE 502 also includes a main housing 540 that is disposed at the end of the grapple canister 528 proximal to the arm interface end 507 .

[0191] The EE 502 also includes a force torque sensor (FTS) 542 (the housing for the FTS can be seen in FIGS. 6A-6B). The FTS 542 is mounted inside the EE 502. The FTS 542 is configured to simultaneously measure three axes of force and three axes of moment. The FTS 542 is mounted in the primary load path, which passes through the grapple mechanism 510. The FTS 542 is not within the grapple mechanism. The FTS 542 measures the interface load between the robot arm and the EE. In one embodiment, the FTS 542 includes an FTS hardware frame that is oriented in x and y lateral directions with z axial. Upon load limiting via sensed feedback, soft capture with low initial load (as described herein) by the EE 502 places the interface in a state where the rigidification load can be precisely controlled.

[0192] Disposed at the arm interface end 507 of the EE 502 is a bulkhead 548 that includes multiple connectors 550 for mechanically and electrically connecting the EE 502 to the robot arm. The bulkhead acts as a cable termination point within the EE 502 and includes panel-mounted connectors for various components (e.g., motor modules, sensors, microswitches, cameras / LEDs, etc.).

[0193] At arm interface end 507, EE 502 also includes an EE-arm interface adapter that includes a thermal isolator 546 and a manipulator adapter 544. Thermal isolator 546 can be constructed from titanium. Manipulator adapter 544 can be constructed from aluminum. Manipulator adapter 544 fits into thermal isolator 546.

[0194] 7A-7B, the grapple mechanism 510 is shown in further detail.

[0195] The grapple mechanism 510 includes an outer housing 552 disposed toward the payload-facing end 509 that houses the internal components of the grapple mechanism 510 and extends from the main housing 540 to a coupling element 532. The coupling element 532 is attached to the payload interface end of the housing 552.

[0196] The grapple mechanism 510 further includes a grapple motor module 554 for driving the grapple mechanism 510 during grappling and rigidification.

[0197] The front end of grapple mechanism 510 is shown in Figure 7B. Grapple mechanism 510 includes grapple jaws 556a and 556b (collectively referred to as grapple jaws or jaws 556 and generally referred to as grapple jaws or jaws 556), which are disposed within grapple canister 528 near opening 534 in coupling element 532.

[0198] The grapple jaws 556 are configured to move between an open configuration and a closed configuration. When in the open configuration, the jaws 556 are capable of receiving the probe 512 of the grapple fixture 508. When in the closed configuration, the jaws 556 are capable of grappling or grasping the probe 512 such that the probe 512 (and thus the payload 516) is captured.

[0199] Disposed between the grapple jaws 556 is a probe presence sensor bar 557. The probe presence sensor bar 557 is used to sense when the probe 512 of the grapple fixture 508 is between the jaws 556 in a grappling position or area (e.g., the "grappling area 568" as shown in FIG. 8).

[0200] The probe presence sensor bar 557 is triggered when contacted by the tip of the probe 512. Upon sensing the presence of the probe 512 by the probe presence sensor bar 557, the grapple mechanism 510 is configured to close the jaws 556 to capture the probe 512.

[0201] 8, the payload-facing end 509 of the grapple mechanism 510, including the coupling element 532, is shown in greater detail.

[0202] The coupling element 532 is mounted to the payload interface end 509 of the housing 540 of the grapple canister 528 via fasteners 564 that are received through radially distributed mounting holes 562 in the coupling element 532.

[0203] Coupling element 532 includes six teeth 558. In other embodiments, the number of teeth 558 can vary. Teeth 558 are radially disposed around the periphery of coupling element 532.

[0204] The teeth 558 are separated by similarly radially disposed recesses 560 (or notches 560).

[0205] 8, the mounting holes 562 are disposed in the recesses 560 (one hole in each recess). In other embodiments, the mounting holes 562 can be located elsewhere on the coupling element 532.

[0206] 8 may be referred to as a hexahirth coupling element or a hexahirth design (which includes a Hirth-type coupling with six teeth). Thus, coupling element 532 may be configured to act as one half of a Hirth coupling (whether with six teeth or another number of teeth).

[0207] The recesses 560 interface with the teeth (teeth 584 in FIG. 9 ) of the coupling element 514 of the grapple fixture 508 when the grapple fixture 508 contacts the concave surface 530 .

[0208] Each one of the teeth 558 includes a top surface 559d, a first side surface 559a, a second side surface 559b, and a third side surface 559c.

[0209] The upper surface 559d is substantially flat.

[0210] The third side surface 559c has a concave profile that urges the grapple probe 512 to slide along the side surface 559c toward the opening 534 when the grapple probe 512 contacts the side surface 559c of the tooth 558 (e.g., if the grapple probe 512 is misaligned with the opening 534 as it approaches). As such, the side surface 559c of the tooth 558 can be considered to form part of the concave surface 530.

[0211] The side surfaces 559a, 559b of the teeth 558 have a curved profile to encourage the teeth on the coupling element 514 of the grapple fixture 508 to slide into the recesses 560 during capture and rigidification to promote effective mating of the complementary coupling elements 514, 532.

[0212] 9, the grapple fixture 508 of FIG. 5 is shown in more detail. The grapple fixture 508 is shown in isolation. In use, the grapple fixture 508 is attached to a payload 516, as in FIG. 5.

[0213] As previously mentioned, the grapple fixture 508 includes a grapple probe 512 and a coupling element 514 .

[0214] The grapple probe 512 includes a shaft 576 that is attached to the coupling element 514 at a probe mounting end 578. The probe 512 is attached to the coupling element 514 at a generally central location on the coupling element 514.

[0215] The grapple probe 512 includes a probe tip 570 at the end of the shaft 576 opposite the probe mounting end 578. The probe tip 570 has a rounded (convex) first surface 572 and a flat second surface 574. The probe tip 570 design can be thought of as a hemispherical design. The rounded first surface 572 allows the probe tip 570 to contact and slide along the concave surface 530 towards the opening 534 of the coupling element 532. The flat second surface 574 provides a flat surface against which the grapple jaws 556 can close and grapple the probe 512 such that the probe tip 570 is grappled around the second surface 574. For example, once the jaws 556 are closed, the jaws 556 can be retracted and the probe 512 can be pulled further into the grapple canister 528 via contact with the flat second surface 574 of the probe tip 570.

[0216] Coupling element 532 includes a mounting surface 582 and a mating surface 580 that generally face one another.

[0217] The mounting surface 582 is used to mount the coupling element 532 (and thus the grapple fixture 508) to the payload 516. The mounting surface 582 may have a generally flat profile.

[0218] The mating surface 580 of the coupling element 514 has a convex profile that is generally complementary to the concave profile of the coupling element 532 of the EE 502, allowing the two surfaces to come into contact and mate during rigidification of the interface.

[0219] The mating surface 580 includes a number of recesses 588 that include mounting holes for receiving fasteners (not shown) for mounting the coupling element 514 (and grapple fixture 508 ) to the payload 516 .

[0220] Coupling element 514 includes six teeth 584. The number of teeth 584 on coupling element 514 matches the number of recesses 560 in coupling element 532 of EE 502. As with coupling element 532 of EE 502, in other embodiments, the number of teeth 584 can vary and match the number of recesses 560 in coupling element 532.

[0221] The size and profile of the teeth 584 are generally complementary to the recesses 560 of the coupling element 532 such that the teeth 584 fit into the recesses 560. The coupling element 514 can act as one half of a Hirth coupling with the coupling element 532 of the EE 502. The load can be distributed symmetrically around the interface. Therefore, there should be a minimum of two teeth / lobes / keys. FIG. 8 shows how tightly the lobes and fasteners are arranged on the EE side of the i / f. For this diameter of the interface, the number of teeth is adequate for the operational loading of typical assembly and pick and place operations for a 2 or 3 meter arm. For other applications, the contact force can be lowered with more teeth, which can protect the surface finish and improve fracture resistance over the operational life time. The system can include more teeth with a larger diameter interface, which would typically be sized to take a larger load. For example, the latching end effector curvic coupling is designed to withstand the rotational loads encountered when maneuvering the 80,000 kg Space Shuttle.

[0222] The teeth 584 are radially disposed about the periphery of the coupling element 514. The teeth 584 are separated by notches 586. The notches 586 comprise recessed portions of the coupling element 514 at the outer periphery. The notches 586 have a generally complementary size and profile to the teeth 558 of the coupling element 532 such that the notches 586 mate with the teeth 558.

[0223] The cutout 586 includes side surfaces 587a, 587b, 587c, respectively, which contact respective mating side surfaces 559a, 559b, 559c of the teeth 558 of the coupling element 532 during mating. The side surfaces 587a, 587b, 587c each have a curved or rounded profile to facilitate sliding of the teeth 558 of the coupling element 532 of the EE 502 into the cutout 586. Thus, misalignment between the coupling elements 514, 532 when they are brought together during capture can be passively compensated for to facilitate mating.

[0224] 10A and 10B, there is shown the front end of the grapple mechanism 510 and grapple fixture 508 in a pre-capture configuration 1002 and a post-capture rigidified configuration 1004. Although the grapple fixture 508 is shown in isolation, it should be understood that the grapple fixture 508 is attached to a payload 516 in application.

[0225] In FIG. 10A, the front end of the grapple mechanism 510 is moved by a robotic arm (not shown) towards the grapple fixture 508 for capture and rigidification.

[0226] As can be seen, the probe tip 570 of the grapple probe 512 is generally aligned with the opening 534 of the coupling element 532 such that as the EE 502 is moved further towards the grapple fixture 508, the grapple probe 512 will enter the grapple canister and into a grappling position between the jaws 556. If the probe 512 is misaligned with the opening 534, the probe tip 570 can contact the concave surface 530 of the coupling element 532 and continued movement of the EE 502 towards the grapple fixture 508 causes the probe tip 570 to slide along the concave surface 530 towards and through the opening 534. A spring is present in the GF base to allow for probe deflection during misalignment cases.

[0227] In FIG. 10B, tip 570 and then the entire grapple probe 512 has entered grapple opening 534 and is grappled by grapple jaws 556a, 556b (not visible in FIG. 10B).

[0228] The grapple probe 512 is captured and retracted by the grapple mechanism 510 to contact the coupling elements 532, 514.

[0229] Mating of the coupling elements 532, 514 is achieved when the teeth 558 of the coupling element 532 of the grapple mechanism 510 are received into the notches 586 of the grapple fixture 508 and when the teeth 584 of the grapple fixture 508 are received into the notches 560 of the coupling element 532. Mating is driven by the curved surfaces of the teeth 558 and notches 586, as previously described. The mating of the teeth 558, 584 and the recesses / notches 586, 560 brings the mating surface 580 of the grapple fixture 508 into contact with the concave surface 530 of the grapple mechanism 510.

[0230] The resulting post-capture interlocking interface can advantageously minimize or prevent accidental separation of the interface before the grapple mechanism 510 purposefully pushes the probe 512 back against the grapple jaws 556a, 556b for release.

[0231] In Figure 10B, rounded side surfaces 559a, 559b, 559c, 587a, 587b, and 587c encourage teeth 558, 584 to slide into recesses 560, 586, promoting capture. Thus, upon successful capture, rounded side surfaces 559a, 559c, 559c are in contact with rounded side surfaces 587a, 587b, 587c.

[0232] The coupling element 532 of the grapple mechanism 510 serves as the mating and alignment interface of the grapple mechanism. The coupling element 532 is a hexahearth face coupling interface design, which improves the overall composite load capacity. The hexahearth design can use a 60 degree contact angle. The hexahearth coupling element 532 is completely separate from the rest of the hardware in the grapple mechanism 510 and can be bolted onto the main housing via six fasteners with a dwell for alignment. The 60 degree contact angle can advantageously provide the best friction angle at the interface. Rotational play around the roll axis ("tick-tock") at the interface between the end effector 502 and the grapple fixture 514 can be eliminated. The hexahearth design of the coupling element 532 can enable capture of the grapple fixture 514 when the grapple interface positional misalignment is within a worst-case combined envelope of ±20 mm in translation, ±5 degrees in wobble (pitch and yaw combined), and ±1.5 degrees in roll. In other words, the end effector 502 is capable of capturing the grapple fixture 514 at these worst-case misalignments without a vision system in the loop to correct the alignment prior to grappling.

[0233] Dry lubricating the anodized working surfaces of the coupling element 532 allows for a 60 degree face-gear contact angle without risk of wedge locking, allowing for reliable separation of the interface without risk of cold welding or galling. Note, however, that this can create a very high resistivity surface (insulating). Therefore, a secondary charge flow path can be implemented so that contact does not rely solely on the lubricated surface. A set of ground fingers located on the interface grapple fixture 514 can be used to contact the conductive surface on the hexahearse of the coupling element 532 in non-structural and non-functional locations (e.g., the fingers create a bond between the grapple fixture 514 and the end effector 502 after being grappled and rigidified).

[0234] 11, a cross-sectional side view of a grapple mechanism 510 showing internal components is shown, in accordance with an embodiment.

[0235] The grapple mechanism 510 in FIG. 11 is in a fully forward position in which the grapple mechanism 510 is ready for capture and ready to receive the grapple probe 512 of the grapple fixture 508.

[0236] The grapple mechanism 510 includes a capture axis 588, which is the axis along which components of the grapple mechanism 510 (and the captured grapple probe 512) move during capture and release.

[0237] At the front end of the grapple mechanism 510 is a coupling element 532 with an opening 534 therein for receiving the grapple probe 512 in a grappling position 568 between the (open) jaws 556a, 556b.

[0238] The various internal components of the grapple mechanism 510 used to achieve grappling, rigidification, and release will now be described.

[0239] The grapple mechanism 510 uses a grapple motor module 554 and several other internal components to meet the performance requirements of the grapple mechanism 510.

[0240] In one embodiment, the grapple motor module 554 includes a fully redundant (dual-wound) DC brushless motor, a fully redundant (dual-wound) single-friction interface electromechanical power-to-lift brake, primary and redundant resolvers, and a planetary gearbox. The gearbox can have a maximum ratio of 100:1. The power-to-life brake design implies that the brake is applied without power and that an operating voltage (nominal required voltage) is required to disengage the brake on the motor. Thus, the brake can advantageously allow a preload configuration to be maintained without a power draw being required.

[0241] The output of the grapple motor module 554 interfaces with a gear path (e.g., a 3:2:1 gear path) that includes an input gear (not shown), an idler gear 1102, and a grapple drive gear 1104. The grapple mechanism 510 further includes a gear housing 1106. A gearbox cover 1107 protects and isolates the input gear, the idler gear 1102, the grapple drive gear 1104, and the gear housing 1106.

[0242] The motor module output shaft 1108 drives an input gear (keyed from the motor shaft), which in turn drives the idler 1102 and finally rotates the grapple drive gear 1104. The gears are each supported by needle rollers (the gears used in the EE502 design are supported on both sides whenever possible).

[0243] A gear housing 1106 above the gear path positions the motor shaft 1108 and the ball screw shaft 1110 and also holds the gear path together.

[0244] The grapple drive gear 1104 at the output of the gear path rotates the ball screw 1110, which is also a keyed interface. The ball screw 1110 is mounted on angular contact bearings 1112a, 1112b (collectively referred to as angular contact bearings 1112 and commonly referred to as bearings 1112) to both radially locate the ball screw 1110 and to carry all of the thrust loads in the design.

[0245] A ball screw collar 1114 is disposed directly behind the angular contact bearing 1112 and clamps the bearing 1112 in place. All of the thrust load is transferred to the split collar 1114. The configuration of components described above allows for some axial flexibility.

[0246] The grapple mechanism 510 further includes a bearing retainer 1116 about the ball screw collar 1114. All of the axial loads generated during rigidification in the ball screw 1110 are reacted through the passage of the ball screw collar 1114, through the angular contact bearing 1112, and into the main housing 1118 of the grapple mechanism 510.

[0247] The grapple mechanism 510 further includes a ball nut 1120 on the output end of the ball screw 1110. A screw sleeve 1122 interfaces with the ball nut 1120 and moves with the ball nut 1120 relative to split housings 1124a, 1124b (collectively referred to as the split housing 1124) during rigidification. The split housing 1124 includes Belleville washers 1126a, 1126b (collectively referred to as the Belleville stack 1126). The foregoing elements and their relative motion can advantageously provide lower stiffness in the grapple mechanism 510 during capture and rigidification.

[0248] When the probe 512 of the grapple fixture 508 enters the jaws 556 (as indicated by the payload present probe bar 557), retraction is effected through the grapple mechanism 510 by the jaw housing 1128 (which houses the jaws 556) connected to the split housing 1124, the screw sleeve 1122, and the ball nut 1120. These components 1128, 1124, 1122, 1120 move along the axis of the capture 588 along the ball screw 1110 towards the arm interface end 507 until the grapple fixture 508 is captured (i.e., the jaws 556 are fully closed around the grapple probe 512).

[0249] Once the jaws 556 are closed, the grapple mechanism 510 continues to pull the grapple probe 512 along the axis of the capture 588 at the start of the rigidification process, and the components 1120 , 1122 , 1124 , 1128 continue to move along the ball screw 1110 .

[0250] Towards the end of the rigidification process, the screw sleeve 1122 and ball nut 1120 continue to move along (and are pulled by) the ball screw 1110, but now move relative to the split housing 1124. The split housing stops moving along the ball screw because the GF is now seated on the face of the EE. This prevents the GF probe from being retracted any further (the split housing is connected to a jaw that is now seated on the underside / flat side of the probe tip). There may be a spring in the payload present bar, or there may be a set of springs that keep the payload present switch engaged during rigidification. The relative motion between the screw sleeve 1122 and the split housing 1124 compresses the Belleville stack 1126, which creates the necessary preload in the grapple mechanism 510.

[0251] The rigidification through compression of the Belleville stack 1126 is shown in Figures 12A and 12B.

[0252] Figure 12A shows the grapple mechanism 510 having captured and made contact with the coupling element 514 of the grapple fixture 508 (via coupling element 532). At this stage, the Belleville stack 1126 is uncompressed. The jaw housing 1128, split housing 1124, screw sleeve 1122, and ball nut 1120 have retracted along the ball screw 1110 to the position shown in Figure 12A.

[0253] 12B illustrates a grapple mechanism 510 that rigidifies the interface with the grapple fixture 508 by generating a target preload through compression of the Belleville stack 1126. Compression of the Belleville stack 1126 is achieved via relative motion between the split housing 1124 and the screw sleeve 1122.

[0254] Specifically, translation of the split housing 1124 (along with the jaw housing 1128) along the capture axis is stopped, while translation of the screw sleeve 1122 (and ball nut 1120) continues along the capture axis in the direction 1148 away from the payload interface end. As this occurs, the Belleville stack 1126 is compressed between an end-facing surface 1152 (proximal to the arm end) of the split housing 1124 (which is stationary) and an end-facing surface 1154 (proximal to the payload end) of the screw sleeve 1122 (which continues to move in the direction 1148 along the capture axis 588 toward the surface 1152 of the split housing 1124).

[0255] The translation of the ball nut 1120 and screw sleeve 1122 relative to the split housing 1124 is measured and monitored to generate a target preload in the Belleville spring stack 1126 .

[0256] The grapple jaws 556a, 556b are secured to the jaw housing 1128 via jaw pins 1130a, 1130b, respectively (collectively referred to as jaw pins 1130), which allow the jaws 556 to pivot open and close as the jaw housing 1128 and the screw sleeve 1122, split housing 1124, and ball nut 1120 move along the ball screw 1110.

[0257] The jaws 556a, 556b are actuated by cams or tension springs 1131a, 1131b. The jaws 556 are forced open in the fully forward position of the grapple mechanism 510, and the cams or tension springs 1131a, 1131b act to hold the jaws 556a, 556b closed in their extended positions.

[0258] The jaws 556 are forced open in the fully forward position of the grapple mechanism 510 and are actuated closed by cams or tension springs 1131 a, 1131 b when the jaw housing 1128, split housing 1124, and screw sleeve 1122 are retracted for rigidification. Slotted guides 1132 a, 1132 b in the jaw housing 1128 guide movement of the jaws 556 as they pivot about the jaw pins 1130 a, 1130 b via jaw guide pins 1130 a, 1130 b on the jaws 556 themselves from their “open” to their “closed” positions.

[0259] 13, a partially transparent perspective side view of the grapple jaw 556 is shown illustrating actuation of the grapple jaw 556 between an open configuration 1302 and a closed configuration 1304, according to an embodiment.

[0260] The cam 1144 actuates the grapple jaws 556. When the cam 1144 moves in a first direction 1146, the grapple jaws 556 open. When the cam 1144 moves in an opposite second direction 1148, the grapple jaws 556 close.

[0261] The payload present microswitch senses whether a payload is present according to whether the payload present bar 557 is triggered. The payload present microswitch is mounted on a mount 1142 that is disposed below the ramp 1140, all of which is disposed above the slider 1138 between the cams 1144.

[0262] The hard capture preload is supported by a flat surface behind the probe tip to significantly reduce internal loads, including contact stresses, allowing the use of standard materials and processes.

[0263] The inner jaws 556 of the grapple canister 1128 use a flat-bottom design at the point of engagement with the grapple probe 512 and are actuated by the linear motion of the grapple mechanism 510. This profile, in cooperation with the hemispherical probe tip 570 of the grapple fixture 508, can significantly reduce internal mechanism loads.

[0264] Referring again to FIG. 11, the grapple mechanism 510 further includes jaw housing guides 1132a, 1132b for retaining the jaw housing 1128, the screw sleeve 1122, and the split housing 1124 and for preventing them from rotating given movement of the ball nut 1120.

[0265] Operation of the jaw housing guides 1132a, 1132b instead limits motion to linear motion along the axis of the capture 588. The hardware and components described above are enclosed by a main housing 540 of the grapple mechanism 510.

[0266] To help determine unambiguous mechanism states during operation, three sets of primary and redundant microswitches are implemented in the grapple mechanism 510. In a variant, a single microswitch can be used instead of the primary and redundant microswitches.

[0267] The microswitches include a payload present microswitch 1150 (shown in FIG. 13), a calibration microswitch 1134, and a rigidification safety microswitch 1136.

[0268] The calibration microswitch 1134 and the rigidification safety microswitch 1136 are stationary inside the mechanism, in other words, these microswitches 1134, 1136 remain fixed relative to the movement of the mechanism 510 during rigidification, and a feature on the moving mechanism triggers the switches 1134, 1136 at a known, pre-determined position.

[0269] A payload present microswitch 1150 is mounted on the slider 1138, which allows the switch 1150 to move with the mechanism 510 during rigidification, thus maintaining the "payload present" state throughout the rigidification process.

[0270] These switches 1150, 1134, 1136 are described in more detail in the following sections.

[0271] The payload present microswitch 1150 (which in this embodiment includes a primary and a redundant microswitch) senses whether a payload is present, i.e., whether the grapple probe 512 of the grapple fixture 508 is in the jaws 556 of the grapple mechanism 510. The switch state is used by software to detect the presence of a payload as a trigger for the payload capture and rigidification sequence performed by the grapple mechanism 510. As a result, appropriate motions are initiated based on the state to achieve the mechanism motion profile. The software can be implemented on the robot arm controller or on the robot workstation. An embodiment includes the software on the arm control computer (on board the spacecraft) and / or in the robot workstation (operator is either on the ground or on the space station). The software can be processed and acted upon in the "state machine" layer of processing, where sequential tasks are scheduled, executed, monitored, and checked for completion.

[0272] The payload present microswitch 1150 is fastened to a small mount 1142, which is mounted on a ramp 1140 that moves with the slider 1138. These features are shown in FIG. 13. The microswitch slider 1138 contains a central spring in a guide (not visible in FIG. 13) that is compressed by the payload present bar 557 when the bar 557 is pushed down by the tip 570 of the grapple probe 512 that is inserted deep enough inside the jaws 556 to be captured (i.e., inserted into the grappling position 568). It is the movement of the payload present bar 557, via spring compliance, that pushes the microswitches 1150 along the slots on their mounts 1142. At the rear end of the slot, the microswitch 1150 is physically depressed by the payload present ramp 1140, which initially provides the "payload present" indication. A set of spring shafts (spring-loaded plungers, not visible in FIG. 13) passing through the slider 1138 then constantly pushes the slider 1138 forward, keeping the microswitch 1150 engaged while the jaw housing 1128, split housing 1124, and screw sleeve 1122 are retracted during the rigidification process. Thus, the payload present indication remains true (indicating that the payload is still present) throughout the rigidification.

[0273] The payload present signal indicates that the GF probe tip is present. After the signal is received, the mechanism must then retract to close the jaws around the GF probe tip even when the offset of the EE 502 relative to the grapple fixture 508 is up to 20 mm (radial capture misalignment) for successful capture.

[0274] 11, the calibration microswitch 1134 is used to sense whether the grapple mechanism 510 is in a calibration position. The microswitch 1134 is used to establish a calibration position of the grapple mechanism 510 after which the position of the mechanism is calculated by keeping track of the motor turns using a motor resolver (present in the motor module 554).

[0275] A rigidification safety microswitch 1136 is used to indicate when the grapple mechanism 510 is approaching its rear hard stop. The microswitch 1136 is used to stop motion of the grapple mechanism 510 before it retracts too far.

[0276] The calibration microswitch 1134 and the rigidification safety microswitch 1136 are actuated by a lamp (not visible in FIG. 11) on the periphery of the screw sleeve 1122. Thus, the assembly of the screw sleeve 1122, split housing 1124, and jaw housing 1128 moves towards the arm interface end 507 during rigidification. Note that the target preload should be achieved before the rigidification safety microswitch 1136 is reached (and can be determined by counting a pre-determined number of motor turns or by current monitoring). The rigidification safety microswitch 1136 is in place for safety in case the mechanism moves too far during rigidification without a payload.

[0277] Reference is now made to Figures 14-21, which illustrate in further detail the socket drive mechanism 520 of the end effector 502 of Figure 5.

[0278] 14A-14C, the socket drive mechanism 520 of FIG. 5 is shown in isolation in perspective, side and cross-sectional views.

[0279] The socket drive mechanism 520 provides clockwise and counterclockwise rotation capability over a continuous range of motion to rotate a torque bolt 524 (a ball head hex bolt) on a payload 516 (e.g., a tool or other hardware). Note that the torque bolt 524 (and prepared interface 504) are not shown in Figures 14A-14C.

[0280] The socket drive mechanism 520 includes a socket head 536 (also referred to as a socket drive 536 or a drive socket 536 ) for interfacing with the torque bolt 524 of the payload 516 .

[0281] The socket drive 536 transmits torque through the torque bolt 524 to the payload 516 .

[0282] The socket head 536 is a spring-loaded socket head. The spring-loaded socket head 536 can be rotated in either direction for a desired number of turns or until a desired torque is reached (e.g., via current limiting). In one embodiment, the maximum output torque capability can be 17 N·m.

[0283] The socket head 536 includes a socket surface 537 that curves toward a socket 538 of the socket head 536 .

[0284] The socket 538 is configured to receive the torque bolt 524 of the payload 516 .

[0285] The socket 538 is shaped for mating purposes to be complementary to the shape of the end of the torque bolt 524. In the embodiment shown, the socket 538 has a hexagonal profile ("socket hex") that is complementary to the profile of the bolt hex of the torque bolt 524.

[0286] Torque bolt 524 of FIG. 5, which is seated and turned by socket 538, is shown in isolation in FIG.

[0287] The torque bolt 524 includes an attachment end 1402 for attaching or connecting the torque bolt 524 to the payload 516 via the second surface 528 of the prepared interface 504, and a socket interface end 1404 for mating and interfacing with the socket 538 of the socket drive mechanism 520.

[0288] In general, the attachment end 1402 of the torque bolt 524 can be connected to a torque driven subsystem of the payload 516 such that rotation of the torque bolt 524 transmits torque to the torque driven subsystem. The torque driven subsystem can be, for example, a component of a tool.

[0289] The torque bolt 524 includes a flat hexagonal top surface 1406 and a flat hexagonal bottom surface 1408. The top surface 1406 has a smaller diameter than the bottom surface 1408.

[0290] The torque bolt 524 further includes six side surfaces that traverse from the top surface 1406 to the bottom surface 1408. The side surfaces each include a flat portion 1410 proximal to the mounting end 1402, a rounded portion 1414 proximal to the socket interface end 1404, and a concave portion 1412 between the rounded portion 1414 and the flat portion 1410. The concave portion 1412 is narrower than each of the rounded portion 1414 and the flat portion 1410.

[0291] The area of ​​the torque bolt 524 defined by the rounded portion 1414 and the top surface 1406 forms a ball end 1416. In one embodiment, the ball end 1416 is a ball end hex head. The ball end makes it easier to engage a socket with an offset angle (±10° in this design). 30° may be typical for land-based applications. This is advantageous for robotic engagement with the socket. The drawback is that with a ball head, the contact force is higher than with a straight hex head. Also, shear forces may be higher within the ball head itself. The profile (rounded leading edge) of the socket interface end 1404 of the torque bolt 524 allows the torque element 524 to slide under the socket face 537 towards the socket 538 to engage with the socket 538.

[0292] Further details regarding the profile of socket 536 are shown in Figures 16A and 16B.

[0293] The socket drive 536 has a rounded hex profile (eg, a 7 / 16" rounded hex profile complementary to a 7 / 16" hex bolt) to transmit torque to the torque bolt 524.

[0294] The socket profile provides a rotational “dead band” that provides some play while backdriving the socket drive motor (not shown) to eliminate wind up caused when torquing the torque bolt 524.

[0295] The socket profile minimizes corner loading on the hex bolt 524 during high torque applications compared to a straight hex profile.

[0296] Additionally, the ball-end (Bondhus head) bolt profile and complementary socket profile of the torque bolt 524 advantageously provide angular misalignment accommodation (e.g., up to 10°) with respect to the socket. Such misalignment accommodation is illustrated in FIG. 16B.

[0297] 14A-14C, the socket drive mechanism 520 further includes ground wires 1418a, 1418b (collectively referred to as ground wires 1418) for grounding the socket drive mechanism 520.

[0298] The socket drive mechanism 520 also includes an Oldham coupling 1420 .

[0299] The Oldham coupling 1420 provides additional compliance to the socket drive 536 during the torquing operation.

[0300] Also, the Oldham coupling 1420 is used to accommodate misalignment of the bolt 524. The Oldham coupling 1420 can be used to rotate the socket drive mechanism 520 to achieve interfacing with the torque bolt 524. The Oldham coupling 1420 helps the socket drive 536 engage onto the torque bolt 524 when the grapple mechanism 510 is rigidified. Rotation of the socket drive 536 may be required for final alignment of the hex 538 (i.e., for the socket drive to reach an engaged state). The Oldham coupling 1420 provides a larger misalignment capacity between the bolt 524 and the socket axis 1430 to accommodate tolerance and thermal induced changes.

[0301] The Oldham coupling 1420 is shown in more detail in Figures 17A and 17B, which show the socket drive mechanism 520 with the Oldham coupling 1420 in assembled and exploded views, respectively.

[0302] The Oldham coupling 1420 includes a socket head 536, a drive slider 1452, an adapter 1450, a spacer 1424, and a retaining ring 1422. The Oldham coupling 1420 as a whole addresses shaft misalignment. The individual pieces allow for connection or interface to a torque housing and a ball hex head, respectively (e.g., 1408a, 1408b).

[0303] In one embodiment, the Oldham coupling 1420 is sized to provide a maximum radial compliance of 0.075" (1.90 mm). Referring to FIG. 18, the radial compliance provided by the socket drive mechanism 520 through the Oldham coupling 1420 is illustrated in graphs 1426a, 1426b, and 1426c. In one embodiment, a maximum radial compliance of .075" (1.90 mm) is provided. The graphs show examples of three different directions of possible radial misalignment that can be accommodated. The graphs show the offset of the socket head 536 (which is to be engaged over the ball hex head on the payload) relative to the adapter 1450 (which is bolted to the torque drive shaft). The position of 1420 (more specifically, the relative positions of 1452 and 1450) in each view of FIG. 18 is compared to the red arrows in the graphs.

[0304] The additional compliance provided by the Oldham coupling 1420 can advantageously eliminate side loads caused by misalignment of the bolts 524 that might otherwise be transmitted to the splines 1432 (shown in FIG. 14C) and motor module bearings (not shown).

[0305] An additional deadband may be inherent in this design, which may advantageously minimize the risk of backing out the bolt 524 when attempting to unwind the system 500 after torquing.

[0306] The Oldham coupling 1420 features are held axially in place by a retaining ring 1422 and a spacer 1424 .

[0307] 14A-14C, the socket drive mechanism 520 further includes an axially compliant drive 1428 (also referred to as an axial compliance mechanism 1428) for providing axial compliance to the socket drive 536.

[0308] The axial compliance mechanism 1428 provides a passive means for retracting the socket 536 when in contact with the torque bolt 524 during grappling and rigidification.

[0309] Generally, the socket drive 536 retracts via the axial compliance mechanism 1428 when the socket hex 538 is misaligned with the bolt hex of the torque bolt 524 .

[0310] The socket drive 536 can then be rotated (e.g., using the Oldham coupling 1420) for final alignment of the socket hex 538 until it is properly seated on the torque bolt 524.

[0311] Achieving proper alignment and seating of the socket hex 538 enables the socket drive mechanism 520 to reach a socket drive engaged state (including microswitch sensing, as further described herein).

[0312] The axial compliance is engaged in an axial compliance cavity 1429 .

[0313] 19 and 20, the axial compliance mechanism 1428 of the socket drive mechanism 520 is shown in greater detail.

[0314] FIG. 19 illustrates the socket drive mechanism 520 in isolation from the axial compliance mechanism 1428 in a first state 1902, a second state 1904, and a third state 1906.

[0315] In the first (forward) state 1902, the socket drive 536 is moving towards the torque bolt 524 as the end effector 502 rigidifies the interface with the payload 516. The torque bolt 524 in this instance is misaligned with the socket hex 538 of the socket drive mechanism 520. When the misaligned torque bolt 524 contacts the socket 538, the axial compliance mechanism 1428 is engaged.

[0316] In the second (retracted) state 1904, the torque bolt 524 contacts the socket 538 but is misaligned and engages the axial compliance mechanism 1428. The axial compliance mechanism 1428 causes movement of the socket drive 536 (and other components of the socket drive mechanism 520) in the direction 1448a. The engagement of the axial compliance mechanism 1428 causes a state change (sensed by a socket-engaged microswitch, described in more detail herein). The state change is registered and used as an indication to rotate the socket drive 536. For example, the state change can be communicated to an operator, who can then rotate the socket drive 536 using the Oldham coupling 1420. The socket drive 536 is rotated until the socket 538 is properly seated on and aligned with the torque bolt 524.

[0317] In the third (forward) state 1906, the socket 538 of the socket drive mechanism 536 is seated on and aligned with the torque bolt 524. This seating is achieved via rotation of the socket drive 536 as previously described. Once properly seated, the axial compliance mechanism 1428 disengages, causing the socket drive 536 (and additional components of the socket drive mechanism 520) to move in the direction 1448b, returning the socket drive 536 to its forward position as in the first state 1902. As the socket drive 536 moves in the direction 1448b, the axial compliance mechanism 1428 causes a second state change (sensed by the socket-engaged microswitch). The state change is registered and used as an indication that the socket 538 is properly seated on the torque bolt 524 and that a torquing operation may be performed. Thus, the state change can be communicated (e.g., to an operator or to another system component configured to autonomously initiate or perform a torque application operation) to enable a torque application operation to commence.

[0318] FIG. 20 illustrates a cross-sectional view of the socket drive mechanism 520 with the axial compliance mechanism 1428 in the first and second positions 1902, 1904 of FIG.

[0319] The splined shaft 1432 provides axial freedom while transmitting torque from a motor module (motor module 1438, described below). The wave springs 1434a, 1434b (referred to as one or more wave springs 1434) provide forward pressure, allowing the socket drive 536 to extend forward to engage the torque bolt 524 (not shown in FIG. 20) when the socket hex 538 is aligned with the torque bolt 524.

[0320] When the axial compliance mechanism 1428 is in the first (forward) state 1902, the splined shaft 1432 is disposed in the distal end of the axial compliance cavity 1429 (distal to the payload interface end of the socket drive mechanism 520).

[0321] The wave spring 1434 applies a forward pressure to the socket drive 536. A cross-sectional view of the third state 1906 of the axial compliance mechanism will look the same as the first state 1902 of FIG. 20 (because in the third state 1906, the socket drive 536 has returned to its forward position).

[0322] When the axial compliance mechanism 1428 is in the second (retracted) state 1904, contact between the socket drive 536 and the misaligned torque bolt 524 compresses the wave spring 1434, causing retraction of the socket drive 536. The passive retraction of the socket drive 536 via compression of the wave spring 1434 causes the splined shaft 1432 to move further into the axial compliance cavity 1429.

[0323] When the axial compliance mechanism 1428 moves to the third (forward) state 1906 (not shown in FIG. 20 ) with the socket 538 aligned and seated on the torque bolt 524, the wave spring 1432 expands (decompresses), causing passive forward movement of the socket drive 536 to a forward position and causing the splined shaft 1432 to return to the distal end of the axial compliance cavity 1429 (as in the first state 1902).

[0324] Translation (rear and forward movement) of the socket drive 536 occurs along the socket axis 1430 .

[0325] 14A-14C, the socket drive mechanism 520 includes a socket drive motor module 1438 (or motor module 1438).

[0326] The motor module 1438 can be used to drive various components of the socket drive mechanism 520 (including driving the rotation of the socket drive 536 to apply torque to the torque bolt 524).

[0327] In one embodiment, the motor module 1438 can have a baseline gear ratio of 480:1. The motor module 1438 mounts to the assembly via a motor mount 1444. The motor module 1438 includes an output shaft 1462. The output shaft 1462 is pinned to the splined (or polygonal) shaft 1432 via a dowel 1458. The dowel 1458 between the motor module output shaft 1462 and the splined shaft 1432 is fixed in place via a dowel retainer sleeve 1460. The splined shaft 1432 engages an Oldham coupling 1420 of the socket drive mechanism 520. The Oldham coupling 1420 includes three features: a splined shaft adapter 1428 (also shown in FIG. 17A), a drive adapter 1450 and drive slider 1452, and a socket 536.

[0328] In one embodiment, the motor module 1438 includes a fully redundant (dual winding) DC brushless motor, a resolver (which may include a primary and redundant resolver), and a planetary gearbox. The gearbox may have a maximum ratio of 480:1 (baseline).

[0329] The splined shaft 1432 is a separate element from the motor module 1438. This modularity can advantageously provide flexibility in the spline 1432 design, allowing easier integration of potential design modifications. Additionally, motor vendors and the like can advantageously use a standard output shaft 1462 with the addition of a dowel hole (not shown) to hold the dowel 1458, which is for torque transmission and retention of the splined shaft 1432.

[0330] A wave spring 1434 around the splined shaft 1432 allows axial compliance of the socket drive 536 with linear movement. This axial movement allowed by the axial compliance 1428 engages and disengages microswitches 1436a, 1436b (collectively referred to as microswitches 1436) and determines when the socket drive 536 is fully seated on the bolt 524. A retaining ring on the end of the male splined shaft has spacers (1466a / 1466b). The entire compliance assembly 1428 can be held in place by the male splined shaft retaining ring.

[0331] Between the retaining ring and spacer 1422, 1424 on the Oldham coupling 1420 and the splined retainers 1466a, 1466b on the splined shaft 1432 and splined spacer there is a cavity 1429 which is essentially the axial compliance in the socket drive mechanism 520. The cavity 1429 includes four vent holes 1464 around the periphery of the socket drive mechanism 520.

[0332] The socket drive mechanism 520 includes a primary and a redundant microswitch 1436 (socket-engaged microswitch 1436) to indicate when the socket drive 536 is fully seated (or engaged) on the torque bolt 524. In an alternative embodiment, only one microswitch 1436 can be used.

[0333] The primary and redundant socket-engaged microswitches 1436 in the socket drive assembly are mounted on microswitch actuator sliders 1442a, 1442b (collectively referred to as microswitch actuator sliders 1442 and commonly referred to as sliders 1442).

[0334] The slider 1442 interfaces with the socket drive mechanism 520 at slots 1446 a , 1446 b (collectively referred to as slots 1446 ) in the underside of each slider bracket 1442 .

[0335] The socket drive mechanism 520 further includes a microswitch actuator skirt 1440 .

[0336] The microswitch actuator skirt 1440 acts as a trigger for the socket-engaged microswitch 1436. The microswitch actuator skirt 1440 also closes off the view from the environment to protect the internal components from radiation and static electricity.

[0337] The skirt 1440 fits into a slot 1446 in the slider 1442 such that when the socket drive 536 compresses axially via the wave spring 1434 due to the torque bolt 524 pushing back against the socket drive 536, the slider 1442 mechanically actuates the microswitch 1436 given the axial movement of the socket drive 536.

[0338] A slot 1446 in the slider 1442 allows for continuous rotation of the skirt 1440 and thus, the socket drive 536. The microswitch sensing design is capable of tracking only the axial motion of the socket drive 536 to provide an indication of engaged and disengaged socket drive.

[0339] The socket-engaging microswitch 1436 is configured to sense whether the socket head 536 of the socket drive mechanism 520 is fully forward and indicates a state change if the socket head 536 retracts along the socket axis 1430 from the fully forward position. The socket head 536 is on axial compliance 1428 and can be deflected back from the socket-engaging microswitch 1436 if the socket 536 is not aligned on the hex profile of the torque bolt 524. The socket head 536 is nominally fully forward. When grappling the payload 516, if the socket head 536 is not aligned and is deflected back towards the microswitch 1436, the socket head 536 can be turned slightly until the socket head 536 is properly seated and an indication of alignment / proper seating is received (via a change in state of the socket-engaging microswitch 1436). This also establishes a zero position for subsequent rotational movement of the socket drive 536. The zero position can be used when monitoring the torque transmitted to the torque bolt 524 (eg, via the number of turns).

[0340] The socket drive mechanism 520 contains hard stops for its linear movement. The socket drive mechanism 520 may not include rotational hard stops since the mechanism 520 accommodates a continuous range of motion. Operationally, the socket drive mechanism 520 can be driven into a hard stop of an interface fastener (not shown) and baselines that hard stop position as a home position from which it begins counting turns. The socket drive 536 can then be rotated to a known turn count (e.g., while monitoring the current) to determine when the movement is complete.

[0341] 21 through 40, cross-sectional side views of the grapple mechanism 510 and socket drive mechanism 520 of the EE502 are shown in accordance with an embodiment, along with the corresponding physical and electrical switch states for each of the socket engagement microswitch 1436, payload present microswitch 1150, rigidification safety microswitch 1136, and calibration microswitch 1134 throughout the motion sequence performed by the EE502.

[0342] The locations of the socket engagement microswitch 1436, payload present microswitch 1150, rigidification safety microswitch 1136, and calibration microswitch 1134 are shown in FIG. 21A.

[0343] 21B shows an example graphical representation 2402 of the switch states of the microswitches, the format of which will be used to illustrate the switch states throughout an operational sequence. Each of the socket engagement microswitch 1436, the payload presence microswitch 1150, the rigidification safety microswitch 1136, and the calibration microswitch 1134 has a corresponding physical switch state 2402 and an electrical switch state 2404. The physical switch state 2402 can be a depressed state 2406 or an undepressed state 2408. The electrical switch state 2404 can be a high state 2410 or a low state 2412. Generally, when powered on, the depressed physical switch state 2406 corresponds to a low electrical switch state 2412, and the undepressed physical switch state 2408 corresponds to a high electrical switch state 2410.

[0344] Figure 22A shows the end effector 502 in a "rest state" 2302 when the power is off. The corresponding switch states shown in Figure 22B for all switches 1134, 1136, 1150, 1436 are the undepressed and low electrical switch states.

[0345] Figure 23A shows the end effector 502 in a "rest state" 2304 when the power is on. Figure 23B shows the electrical switch state 2404 for each of the switches 1134, 1136, 115, 1436 changed to a high electrical switch state 2410.

[0346] Figure 24A shows the end effector 502 in a powered up state 2306 while at "rest". Figure 24B shows the corresponding switch states 2406 of the switches 1134, 1136, 1150, 1436. The switch states and positions of the mechanisms 510, 520 of the end effector 502 are unchanged from Figures 23A, 23B.

[0347] 25A shows the end effector 502 in the calibration position 2308. The motor module 554 drives the single stage gear path 1102 to rotate the ball screw 1110. As the ball screw 1110 rotates, the ball nut 1120 translates the jaw mechanism (jaw housing 1128, Belleville spring stack 1126, and screw sleeve 1122) forward in the direction 1148. In doing so, the calibration switch 1134 is depressed.

[0348] FIG. 25B shows that the physical switch state 2402 of the calibration switch 1134 has changed to a depressed state 2414 and that the electrical switch state 2404 has changed to a low state 2416.

[0349] 26A shows the end effector 502 in the ready-to-capture state 2310. The motor module 554 further drives the rotation of the ball screw 1110. The ball nut 1120 translates the jaw mechanism to a fully forward position where the jaw housing 1128 bears against the rear face of the coupling element 532. This movement causes the tension spring 1131 to move from an extended state to a free state, actuating the jaws 556 from a closed configuration to an open configuration.

[0350] FIG. 26B shows that the switch states 2402, 2404 for the switches 1134, 1136, 1150, 1436 in the ready for capture state 2310 have not changed from the calibrated positions 2508 of FIGS. 25A, 25B.

[0351] 27A shows the end effector 502 in the approach and capture ready state 2312. The payload interface end of the end effector 502 is moved via a robotic arm (not shown) towards a prepared interface 504 on a payload 516. The prepared interface 504 includes a torque bolt 524 and a grapple fixture 508. A grapple probe 512 of the grapple fixture 508 is within the capture envelope of the end effector 502. The grapple probe 512 is approaching a grapple face of the end effector 502.

[0352] FIG. 27B shows that the switch states 2402, 2404 for the switches 1134, 1136, 1150, 1436 in the approach and ready for capture state have not changed from the ready for capture state 2310 of FIGS. 26A and 26B.

[0353] 28A shows the end effector 502 in a payload present state 2314. Through continued movement of the end effector 502 towards the prepared interface 504 of the payload 516, the grapple probe 512 enters the grapple canister 528 through a grapple opening 534 in the grappling mechanism 510 and into the grappling area 568. The probe tip 570 of the grapple probe 512 contacts the probe present bar 557 at the distal end of the grappling area 568, triggering the probe present microswitch 1150.

[0354] 28B shows that the physical switch state 2402 of the probe presence switch 1150 has changed from not depressed to depressed 2408, and the electrical switch state 2404 has changed from a high state 2410 to a low state 2412 as a result of the probe tip 570 contacting the probe presence bar sensor 557. The end effector 502 now knows that a payload is present (i.e., the grapple probe 512 is in the grappling area 568) and that retraction of the grappling mechanism 510 can begin.

[0355] 29A shows the end effector 502 in a jaw closed state 2315. The jaw closed state 2315 can also be referred to as a "soft capture" state (i.e., the probe head of the grapple fixture has been captured, but rigidification has not yet occurred). Soft capture (with a low initial load) can place the interface in a state where the rigidification load can be precisely controlled. Retraction of the grapple mechanism 510 along the capture axis is initiated, causing the grapple jaws 556 to move from an open configuration to a closed configuration and grapple the grapple probe 512 via the probe tip 570. The motor module 554 drives the single stage gear path 1102, which rotates the ball screw 1110. As the ball screw 1110 rotates, the ball nut 1120 translates the jaw mechanism / assembly 1156 (jaw housing 1128, Belleville spring stack 1126, and screw sleeve 1122) in the direction 1148. As the jaw assembly is retracted along the capture axis, a tension spring 1131 in the jaw assembly 1156 moves from a free state to an extended state, actuating the grapple jaws 556 from an open configuration to a closed configuration. As can be seen, the retracting jaw assembly 1156 approaches the calibration switch 1134.

[0356] FIG. 29B shows that the switch states 2402, 2404 for the switches 1134, 1136, 1150, 1436 in the jaw closed state 2315 have not changed from the payload present state 2312 of FIGS. 29A, 29B, and that the payload present switch 1150 remains engaged.

[0357] 30A shows the end effector 502 in initial socket drive contact state 2316. The grapple mechanism of the end effector 502 further retracts the grapple probe 512 of the payload 516 by translating the jaw assembly 1156 along the capture axis in the direction 1148, bringing the torque bolt 524 of the payload 516 into contact with the socket drive 536 of the socket drive mechanism 520.

[0358] 30A releases the calibration microswitch 1134, effecting a state change that indicates that the grapple mechanism 510 has passed the home or calibration position. In response to the state change in the calibration switch 1134, a resolver (not shown) in the motor module 554 monitors the motor position (e.g., tracks the turn count) as the jaw assembly 1156 continues its translation along the capture axis.

[0359] Figure 30B shows that the physical switch state 2402 of the calibration switch 1134 has changed from a depressed state 2406 to a not depressed state 2408, and the electrical switch state 2404 has changed from a low state 2412 to a high state 2410. As previously mentioned, this change in switch state is caused by the continued retraction of the jaw assembly 1156 to the position shown in Figure 29A. When the socket head 536 is still in its fully forward position (axial compliance 1428 not engaged), the socket engagement switch 1436 is not yet engaged, as reflected by the not depressed physical switch state 2408 and the high electrical switch state 2410.

[0360] FIG. 31A shows the end effector 502 in a state 2318 corresponding to the coupling element 514 of the grapple fixture 508 contacting the coupling element 532 of the grapple mechanism 510 and the socket 538 not being aligned over the torque bolt 524.

[0361] The misaligned torque bolt 524 contacts the socket head 536 and, due to the misalignment (the torque bolt hex is misaligned with the socket hex), the socket drive 536 is passively retracted in the direction 1148 via the axial compliance mechanism 1428 of the socket drive mechanism 520. Among other things, the contact of the misaligned torque bolt 524 causes compression of the wave spring 1434 in the socket drive mechanism 520 and further movement of the splined shaft 1432 into the (axial compliance) cavity 1429.

[0362] The jaw assembly 1156 with the grappled probe 512 is then retracted further along the capture axis, bringing the coupling element 532 of the grapple mechanism 510 into mating contact with the coupling element 514 of the grapple fixture 508. The mating of the respective coupling elements 532, 514 also promotes alignment.

[0363] 31B illustrates the change in switch state 2402, 2404 of the socket engagement switch 1436 as a result of the misaligned socket drive 536 being deflected back from the torque bolt 524 via the axial compliance mechanism 1428. This retraction of the socket drive 536 depresses the socket engagement switch 1436, changing the physical switch state 2402 to a depressed state 2406 and the electrical switch state 2404 to a low state 2412. The triggering of the socket engagement switch 1436 can be communicated to a robotic workstation in communication with the end effector (or robotic system controlling the end effector 502) such that an operator, using a human-machine interface on the robotic workstation, can command the socket drive mechanism 520 to rotate (using the Oldham coupling 1420) to properly seat the socket 538 on the torque bolt 524.

[0364] FIG. 32A shows the end effector 502 in a state 2320 in which the interface between the grapple fixture 508 and the grapple mechanism 510 has been rigidified, rigidifying the end effector 502 to the payload 516, and the socket 538 is not aligned with the torque bolt 524 ("rigidified and socket not aligned").

[0365] 31A, the grapple motor module 554 further drives the gear path 1102 to rotate the ball screw 1110, causing the ball nut 1120 to translate a screw sleeve 1122 interfacing with the ball nut 1120 in the direction 1148 relative to the jaw assembly 1156. Movement of the screw sleeve 1122 relative to the split housing 1124 of the jaw assembly 1156 compresses the Belleville spring stack 1126, generating the target preload. Retraction of the screw sleeve 1122 is controlled to the target preload position through continuous monitoring of the motor position (movement relative to the calibrated position indicated by an engaged calibration switch 1134) by a resolver in the grapple motor module 554 to the target preload position.

[0366] The socket 538 remains misaligned with the torque bolt 524 (and the socket engagement switch 1436 remains engaged).

[0367] FIG. 32B shows that the switch states 2402, 2404 for the switches 1134, 1136, 115, 1436 in the rigidified state 2320 are unchanged from the grapple fixture contact state 2318 of FIGS. 31A, 31B.

[0368] 33A shows the end effector 502 in a state 2322 in which the interface between the grapple fixture 508 and the grapple mechanism 510 remains rigid and the socket 538 is aligned. In this state, the end effector 502 is ready to perform an operation, such as transmitting torque to the torque bolt 524 through rotation of the socket drive mechanism 520.

[0369] 32A , the socket drive mechanism 520 has been rotated to a point where the torque bolt 524 is properly aligned with the socket 538. When the socket 538 is properly seated on the torque bolt 524, the axial compliance 1428 is released as the wave spring 1434 decompresses and as the splined shaft 1432 retracts within the cavity 1429. As the socket drive 536 moves forward in the direction 1146, the socket engagement switch 1436 is disengaged, changing switch states 2402, 2404.

[0370] The socket engagement switch 1436 can send a signal to a socket drive motor module 1438 to drive the socket drive mechanism 520 (eg, up to a desired number of turns, up to a desired torque (current limit)).

[0371] 33B shows that the physical and electrical switch states 2402, 2404 of the socket engagement switch 1436 have changed, respectively, to a not depressed state 2408 and a high electrical state 2410. This change in switch states 2402, 2404 indicates that the socket 538 is properly seated on the torque bolt 524 and is ready for operation.

[0372] The following diagram corresponds to the release of the payload 516 from the end effector 502.

[0373] 34A shows the end effector 502 in a state 2324 in which the preload generated during rigidification (shown in FIG. 34A) is released. To release the preload, the grapple motor module 554 drives the gear path 1102 to rotate the ball screw 1110, causing the ball nut 1120 to translate the screw sleeve 1122 in the direction 1146 (opposite retraction) along the capture axis relative to the split housing 1124, decompressing the Belleville spring stack 1126.

[0374] FIG. 34B shows that the switch states 2402, 2404 for the switches 1134, 1136, 115, 1436 in the released preload state 2324 are unchanged from the rigidified state 2322 of FIGS. 33A, 33B.

[0375] 35A shows the end effector 502 in the payload released state 2326 in which the grapple mechanism 510 begins to push the grapple probe 512 in the direction 1146. In particular, the ball screw 1110 is rotated, causing the ball nut 1120 to translate the jaw assembly 1156 in the direction 1146 to a point where the jaw housing 1128 contacts the rounded surface 572 of the probe tip 570, pushing the probe 512 in the direction 1146 as the jaw assembly 1156 is further translated in the direction 1146.

[0376] FIG. 35B shows that the switch states 2402, 2404 for the switches 1134, 1136, 1150, 1436 in the payload release state 2326 remain unchanged from the released preload state 2324 of FIGS. 36A, 36B.

[0377] 36A shows the end effector 502 in the payload released state 2328 as the grapple jaws 556 begin to move from a closed configuration to an open configuration. The jaw assembly 1156 is further translated via rotation of the ball screw 1110, and the jaw housing 1128 continues to push the probe tip 570 in the direction 1146. At this stage, the tension spring 1131 begins to move from an extended state to a free state, actuating the grapple jaws 556.

[0378] The jaw assembly 1156 is translated back to or past the calibration position (home position) and engages the calibration microswitch 1134 .

[0379] Additionally, the grapple mechanism 510 pushing against the probe 512 causes the coupling element 514 of the grapple fixture 508 to disengage from the coupling element 532 of the grapple mechanism 510, causing the torque bolt 524 to be released from the socket 538.

[0380] 36B shows that the physical switch state 2402 and electrical switch state 2404 of the calibration switch 1436 have changed to a depressed physical state 2406 and a low electrical state 2412, respectively. This change of state is caused by the jaw assembly 1156 moving past and engaging the calibration microswitch 1134.

[0381] FIG. 37A shows the end effector 502 in a payload release state 2330 with the grapple jaws 556 partially open.

[0382] 36A, the jaw assembly 1156 is further translated in the direction 1146 along the ball screw 1110. This movement urges the tension spring 1131 of the jaw assembly 1156 further toward its free state, actuating the grapple jaws 556 to open further.

[0383] FIG. 37B shows that the switch states 2402, 2404 for the switches 1134, 1136, 1150, 1436 in the payload release state 2330 are unchanged from the payload release state 2328 of FIGS. 36A, 36B.

[0384] 38A shows the end effector 502 in the payload release state 2332 with the grapple jaws 556 open. Continued forward translation of the jaw assembly 1156 via rotation of the ball screw 1110 pushes the jaw housing 1128 into contact with the rear side of the coupling element 532. Continued forward translation of the jaw assembly 1156 also causes the tension spring 1131 to return to its free state, which actuates the grapple jaws 556 to fully open (open configuration). This fully open state of the grapple jaws 556 allows for release of the grapple probe 512 from the grapple canister 528.

[0385] FIG. 38B shows that the switch states 2402, 2404 for the switches 1134, 1136, 115, 1436 in the payload release state 2332 are unchanged from the payload release state 2330 of FIGS. 37A, 37B.

[0386] 39A shows the end effector 502 in the payload released state 2334. The grapple probe 512 has been released from the grapple canister 528 (enabled by the open grapple jaws 556) and has released the payload from the end effector 502.

[0387] Releasing the grapple probe 512 causes the payload present microswitch 1150 to disengage (due to the probe end 570 no longer pressing down on the payload present bar 557). Payload present can be activated or removed by movement of the end effector onto or off the grapple probe.

[0388] FIG. 39B shows that the physical switch state 2402 and the electrical switch state 2404 of the payload present switch 1150 have changed to not depressed 2408 and to a high electrical state 2410, respectively.

[0389] Figure 40A illustrates the end effector 502 returning to the "rest state" 2336 previously shown in Figure 35A. Movement from the payload released state 2334 of Figure 39A to the rest state 2336 is accomplished by retraction of the jaw assembly 1156 along the capture axis via rotation of the ball screw 1110. As the jaw assembly 1156 retracts, the tension spring 1131 within the jaw assembly 1156 moves from a free state (jaws open) to an extended state, closing the grapple jaws 556.

[0390] FIG. 40B shows that the physical switch state 2402 of the calibration switch 1134 has changed to a not depressed state 2408 and the corresponding electrical switch state 2404 of the calibration switch 1134 has changed from the states 2402, 2404 of FIG. 39B to a high state 2410.

[0391] Although the above description provides examples of one or more devices, methods, or systems, it can be recognized that other devices, methods, or systems are possible within the scope of the claims, as interpreted by one of ordinary skill in the art. [Explanation of symbols]

[0392] 102 Payload 104 Robot System 106 Robot Workstation 108 Machine Vision Target 110 Machine Vision System 112 Robot Arm Controller 114 Robot Arm 116 Multipurpose End Effector 118 Grapple Fixture 120 Torque member 122 Torque-driven Subsystem 124 Coupling element 126 Grapple Probe 128 Probe tip 130 Electrical Umbilicals 132 Camera Subsystem 134 Recognition Module 136 Target Recognition Database 140 Arm Interface End 142 Payload Interface End 144 Robot Arm Interface 146 Grapple Subsystem 148 Torque Subsystem 149 Power / Data Pass-Through Mechanism 150 Grapple Mechanism 152 Grapple Motor Module 154 Grapple Mechanism State Sensing Subsystem 156 Probe receiving end 158 Coupling element 160 Grapple Opening 162 Jaw Assembly 164 Grapple Jaw 166 Jaw actuator 168 Jaw assembly translator 170 compressible elements 172 Probe Presence Sensor 174 Translational Position Tracking Sensor 176 Torque Mechanism 178 Torque motor module 180 Torque Mechanism State Sensing Subsystem 182 Torquer Seating Element 184 Seating element rotator 186 Axial Compliance Mechanism 188 Seating element engagement sensor 500 Systems 502 End Effector (EE) 504 Prepared Interface 506 Payload Interface End 507 Arm Interface End 508 Grapple Fixture 509 Payload Facing End 510 Grapple Mechanism 512 Grapple Probe 514 Coupling element 516 Payload 518 Camera Subsystem 519 Boresight Camera 519a First boresight camera 519b Secondary Boresight Camera 520 Socket Drive Mechanism 521 Photogrammetry Camera 522 Machine Vision Target 524 Torque Element 526 First Surface 528 Second Surface 530 Concave surface 532 Coupling element 534 Opening 536 Socket Drive 537 Socket surface 538 Sockets 540 Main Housing 542 Force Torque Sensor (FTS) 544 Manipulator Adapter 546 Thermal Isolator 548 Bulkhead 550 Connector 552 Outer Housing 554 Grapple Motor Module 556 Joe, Grapple Joe 556a Grapple Jaw 556b Grapple Jaw 557 Probe Presence Bar Sensor, Payload Presence Bar 558 teeth 559a first side surface 559b second side surface 559c Third side surface 559d Upper surface 560 Recess 562 Mounting hole 564 Fasteners 568 Grappling Position, Grappling Area 570 Probe tip 572 Rounded First Surface 574 Flat Second Surface 576 Shaft 578 Probe Mounting End 580 Mating Surface 582 Mounting Surface 584 teeth 586 Notch 587a Side Surface 587b Side surface 587c Side surface 588 Capture Axis 1002 Pre-capture configuration 1004 Post-capture and Rigid Configuration 1102 Idler gear, single stage gear path 1104 Grapple Drive Gear 1106 Gear Housing 1107 Gearbox Cover 1108 Motor module output shaft 1110 Ball screw, ball screw shaft 1112 Angular contact bearing 1112a Angular Contact Bearing 1112b Angular contact bearing 1114 Ball screw collar 1116 Bearing retainer 1118 Main Housing 1120 Ball nut 1122 Screw sleeve 1124 Split Housing 1124a split housing 1124b split housing 1126 Belleville Washer 1126a Belleville washer 1126b Belleville washer 1128 Jaw Housing 1130 Joepin 1130a Joe Pin 1130b Joepin 1131a Cam or tension spring 1131b Cam or tension spring 1132a Slotted Guide, Jaw Housing Guide 1132b Slotted Guide, Jaw Housing Guide 1134 Calibration Microswitch 1136 Rigid safety micro switch 1138 Slider 1140 Lamp 1142 Mount 1144 Cam 1146 First Direction 1148 Second Direction 1150 Payload Present Microswitch 1152 Surface 1154 Surface 1302 Open configuration 1304 Closed Configuration 1402 Attachment end 1404 Socket Interface End 1406 Upper surface 1408 Bottom surface 1410 Flat area 1412 Concave part 1414 Rounded Part 1416 Ball End 1418 Ground Wire 1418a Ground Wire 1418b Ground Wire 1420 Oldham Coupling 1422 Retaining ring 1424 Spacer Graphs 1426a, 1426b, and 1426c 1428 Axial Compliance Mechanism 1429 Axial Compliance Cavity 1430 Socket axis 1432 Spline shaft 1434 Wave Spring 1434a Wave Spring 1434b Wave Spring 1436 Microswitch 1436a Microswitch 1436b Microswitch 1438 Socket Drive Motor Module, Motor Module 1440 Microswitch Actuator Skirt 1442 Micro Switch Actuator Slider 1442a Microswitch Actuator Slider 1442b Micro Switch Actuator Slider 1444 Motor Mount 1446 Slots 1446a Slot 1446b Slot 1448a direction 1448b direction 1450 Drive Adapter 1452 Drive Slider 1458 Dwell 1460 Dwell Retainer Sleeve 1462 Output shaft 1464 Vent hole 1466a Spline retainer, spacer 1466b Spline retainer, spacer 1902 First State 1904 Second State 1906 The Third State 2302 "Rest state" when power is off 2304 "Rest state" when power is on 2306 Power-up status while in "rest state" 2308 Calibration Position 2310 Capture ready 2312 Approach and capture ready 2314 Payload Present Status 2315 Joe is closed 2316 Socket Drive Initial Contact 2318 Grapple Fixture Contact State 2320 Rigidized state 2322 state, rigidified state 2324 Preload is released 2326 Payload Released State, "Rest State" 2328 Payload Released 2330 Payload Released 2332 Payload Released 2334 Payload Released 2402 Physical Switch State 2404 Electrical Switch Status 2406 Pressed down 2408 Not pressed down 2410 High Electrical Switch State 2412 Low Electrical Switch State

Claims

1. 1. A robot end effector device, the robot end effector device having an arm interface end including a robot arm interface for connecting to a robot arm, and a payload interface end for interfacing with a payload having a grapple fixture including a first coupling element and a grapple probe attached to a surface of the payload, the device comprising: a housing for enclosing an internal compartment of the end effector device; a second coupling element connected to the housing at the payload interface end for mating with the first coupling element during rigidification of the end effector to the payload, the second coupling element having an opening therethrough to allow the grapple probe of the grapple fixture to enter the internal compartment when the payload interface end is moved by the robotic arm towards the grapple fixture; a grapple mechanism disposed within the interior compartment for capturing and rigidifying the payload through the grapple fixture to the end effector device; Including, The grapple mechanism includes: a jaw assembly including a jaw for grappling the grapple probe; a payload presence sensor for sensing that the grapple probe is in a position to be grappled by the jaws (a "grappling position"); a translation component for translating along a capture axis of the grapple mechanism in a direction opposite to the payload interface end ("retract") to mate and connect the first coupling element and the second coupling element while the jaws are grappling the grapple probe to rigidify the end effector to a target preload on the payload, the translation component including the jaw assembly, and retraction of the translation component closing the jaws and grappling the grapple probe; a translation mechanism for retracting the moving component along the capture axis; a motor for driving the translation mechanism, the motor being triggered to drive the translation mechanism in response to the payload presence sensor sensing the grapple probe in the grappling position; and a calibration sensor for sensing when the moving component retracts from a calibration position; a position monitoring device for monitoring a position of the moving component relative to the calibration position and for generating an output to stop retraction of the moving component when the moving component reaches a target preload position along the capture axis that achieves the target preload; A robotic end effector device comprising:

2. 2. The device of claim 1, wherein the first and second coupling elements each include a plurality of radially arranged teeth and notches, and wherein when the first and second coupling elements are brought together during rigidification of the payload to the end effector, the teeth of the second coupling element are configured to mate with the notches of the first coupling element and the teeth of the first coupling element are configured to mate with the notches of the second coupling element.

3. 2. The device of claim 1, wherein the first and second coupling elements are configured to each act as one half of a Haas coupling when the first and second coupling elements are mated during rigidification of the payload to the end effector.

4. 3. The device of claim 2, wherein the first and second coupling elements each include six teeth and six notches such that when mated, the first and second coupling elements have twelve points of contact through their respective teeth and notches.

5. 2. The device of claim 1, wherein when the payload is rigidified to the end effector, the first and second coupling elements are engaged together and transmit a static load therebetween without separation of the interface up to a maximum rigidified load capacity of the end effector.

6. 3. The device of claim 2, wherein the teeth of the second coupling element and the complementary cutouts of the first coupling element each include three curved side surfaces to promote alignment of the teeth of the second coupling element with the cutouts of the first coupling element when the first and second coupling elements are engaged.

7. 2. The device of claim 1, wherein the moving component includes a compressible element biased between a first compression surface of a subcomponent of the moving component and a second compression surface of the jaw assembly, the first compression surface facing the arm interface end and the second compression surface facing the payload interface end, such that during retraction of the moving component, the jaw assembly stops retracting before the target preload position and the subcomponent of the moving component continues retracting to the target preload position, with the compressible element compressed between the first compression surface and the second compression surface to generate the target preload.

8. The device of claim 7 , wherein the compressible element comprises at least one Belleville spring stack.

9. 8. The device of claim 7, wherein the translation mechanism includes a gear path driven by the motor and a ball screw rotated by the gear path, and the moving components of the grapple mechanism include the jaw assembly, a screw sleeve, and a ball nut, and rotation of the ball screw causes the ball nut to translate the jaw assembly and the screw sleeve.

10. The device of claim 7, wherein the subcomponent is the screw sleeve.

11. 2. The device of claim 1, wherein the payload sensor includes a sensing element positioned such that the sensing element is triggered by the grapple probe when the grapple probe is inserted deep enough into the jaws to be grappled by the jaws when the jaws close.

12. 2. The device of claim 1, wherein the payload sensor includes a sensing element disposed at a distal end of the grapple position relative to the payload interface end, the sensing element being depressed by a probe tip of the grapple probe when the grapple probe enters the grapple position and generating an output in response to being depressed, the output being used as a signal to initiate retraction.

13. 13. The device of claim 12, wherein the sensing element is connected to the moving component such that the sensing element moves with the moving component during retraction and maintains a state indicative of the payload being present throughout the rigidification.

14. The device of claim 13 , wherein the sensing element is mounted on a slider, allowing the sensing element to move with the moving component.

15. 10. The device of claim 1, wherein the grapple mechanism further includes a brake to maintain the target preload without a power draw being required.

16. 16. The device of claim 15, wherein the brake is an electromechanical power-to-lift brake in which the brake is applied without power and requires an actuation voltage to disengage the brake on the motor.

17. 13. The device of claim 1, wherein the position monitoring device monitors the position of the moving component using at least one of counting a predetermined number of motor turns and sensing a predetermined amount of motor current.

18. The device of claim 17 , wherein the location monitoring device is a resolver.

19. 2. The device of claim 1, wherein the calibration position is a fixed position in which a sensing element of the calibration sensor is disposed within the internal compartment, and the moving component includes a feature that triggers the sensing element when retracted beyond the calibration position.

20. 13. The device of claim 1, wherein the position monitoring device is configured to perform position monitoring of the moving component to a plurality of different target preload positions such that the grapple mechanism can rigidify the interface between the first coupling element and a second coupling element to a plurality of different target preload positions.

21. 21. The device of claim 20, wherein the position monitoring device is configured to perform position monitoring of the moving component to a plurality of different target preload positions such that the grapple mechanism can rigidify the interface between the first coupling element and the second coupling element to a plurality of different target preload positions, a difference between each one of the plurality of target preload positions corresponding to a different amount of compression applied to the compressible element by relative movement of the first and second surfaces.

22. 10. The device of claim 1, further comprising a force torque sensor mounted in a primary load path of the grapple mechanism to limit loads during grappling.

23. 52. The device of claim 51, wherein the force-torque sensor measures three-axis forces and three-axis moments.

24. 13. The device of claim 1, further comprising a first camera mounted above the grapple mechanism to image machine vision markers on the payload and a second camera mounted beside the grapple mechanism to image target fiducials for photogrammetry measurement, the first and second cameras having lenses focused at different distances and different f-numbers.

25. 1. A robotic end effector device, the robotic end effector device having an arm interface end including a robot arm interface for connecting to a robot arm, and a payload interface end for interfacing with a payload, the payload having a grapple fixture for grappling and rigidifying the payload, and a torque element for receiving a torque, the device comprising: a grapple mechanism configured to grapple a grapple probe of the grapple fixture when the payload interface end of the end effector device is moved towards the grapple fixture and configured to retract the grappled probe along a capture axis towards the arm interface end and to orient a coupling element and a torque element of the grapple fixture towards the payload interface end; a socket drive mechanism for transmitting torque to the payload through the torque element on the payload; Including, The socket drive mechanism includes: a socket module having a socket for receiving and seating the torque element; a socket rotator for rotating the socket to impart rotational mechanical energy to the torque element seated in the socket; a socket drive motor module for driving rotation of the socket rotator; an axial compliance mechanism configured to passively retract the socket module axially from a forward position when the socket is misaligned with and in contact with the torque element, and to passively return the socket module to the forward position when the socket is aligned with and seated on the torque element; Including, The socket drive motor drives rotation of the socket rotator when the socket is seated on the torque element to impart the rotational mechanical energy to the torque element.

26. 26. The device of claim 25, wherein the socket drive mechanism further includes a socket engaging sensor for sensing when the socket module is retracted from the forward position, and in response to the socket engaging sensor sensing when the socket module is retracted from the forward position, the socket drive motor module drives the socket rotator to rotate the socket module until the socket is aligned with the torque element, causing the axial compliance mechanism to return the socket module to the forward position.

27. 27. The device of claim 26, wherein the socket engagement sensor is further configured to sense when the socket module returns to the forward position, and in response to the socket engagement sensor sensing that the socket module returns to the forward position, the socket drive motor module drives the socket rotator to rotate the socket such that rotational mechanical energy is applied to the seated torque element.

28. 28. The device of claim 27, wherein the socket drive mechanism is further configured to measure the rotational mechanical energy applied to the torque element and automatically stop rotation of the socket module when a predetermined amount of rotational mechanical energy is applied to the torque element.

29. 30. The device of claim 28, wherein the socket drive mechanism measures the applied rotational mechanical energy by measuring at least one of a number of turns of the socket module and an applied current.

30. 30. The device of claim 29, wherein the socket drive mechanism includes a resolver for monitoring the number of turns of the socket module.

31. 26. The device of claim 25, wherein the axial compliance mechanism includes a wave spring connected to the socket module, the wave spring being compressed when a misaligned torque element contacts the socket, causing a passive retraction of the socket module, and the wave spring being decompressed when the socket is aligned with the torque element, causing the socket module to return to the forward position.

32. 32. The device of claim 31, wherein the socket rotator includes a splined shaft, the socket drive mechanism includes a compliance cavity within which a payload interface end of the splined shaft is disposed, and wherein the compression of the wave spring causes the splined shaft to move further into the compliance cavity.

33. 26. The device of claim 25, wherein the torque element is a hex bolt and the socket has a hex profile ("socket hex") complementary to a profile of the hex bolt.

34. 34. The device of claim 33, wherein the hex bolt includes rounded ends for interfacing with the socket, the hex profile of the socket being rounded to complement the profile of the hex bolt.

35. 35. The device of claim 34, wherein the socket module includes a concave surface disposed at the payload interface end, the socket being centrally disposed above the concave surface.

36. 26. The device of claim 25, wherein the socket drive mechanism further includes an Oldham coupling for providing compliance during a torquing operation and for accommodating misalignment of the torque element.

37. 30. The device of claim 28, wherein the socket-engaging sensor includes a sensing element that is mechanically triggered by a feature on the socket module when the socket module is retracted from the forward position and when the socket module returns to the forward position, the mechanical triggering causing a change in state of the sensing element that is registered by the socket-engaging sensor.

38. 1. A method of robotic capture of a payload, comprising: moving a payload interface end of an end effector via a robotic arm towards a grapple fixture above the payload, such that the grapple fixture is within a capture envelope of the end effector, the payload interface end having a grapple mechanism; sensing that a probe of the grapple fixture is within a grappling area of ​​the grapple mechanism, where the grapple jaws of the grapple mechanism can grapple the probe; in response to sensing that the grapple probe is within the grappling area, retracting the grapple mechanism along a capture axis to close the grapple jaws and grapple the probe; sensing that the grapple mechanism has retracted from a home position; in response to sensing that the grapple mechanism has been retracted from the home position, tracking a position of the grapple mechanism along the capture axis as the grapple mechanism retracts via a position monitoring device; as the grapple mechanism grapples the probe, further retracting the grapple mechanism along the capture axis to a target preload position to retract a first coupling element of the grapple fixture on the surface of the payload into mated connection with a second coupling element on the payload interface end of the end effector, such that the first and second coupling elements transmit a static load between each other without separation of the interface up to a maximum rigidification load capacity of the end effector, the target preload position corresponding to a respective rigidification load; generating an output at the position monitoring device when the grapple mechanism retracts to the target preload position; stopping retraction of the grapple mechanism at the target preload position based on the output of the position monitoring device. A method comprising:

39. 40. The method of claim 38, wherein the payload is a space-based payload and the target preload location is pre-determined and calibrated on Earth prior to performance of the method in a space-based environment.

40. Prior to retraction by the grapple mechanism: selecting said individual rigidification loads from a plurality of individual rigidification loads achievable by said grapple mechanism; communicating the selected individual rigidified loads to the position monitoring device; 39. The method of claim 38, further comprising:

41. 40. The method of claim 38, further comprising engaging a brake after stopping retraction of the grapple mechanism to maintain a preloaded configuration without a power draw being required.

42. Further retracting the grapple mechanism along the capture axis to the target preload position includes:

40. The method of claim 38, comprising compressing a compressible element in a load path of the grapple mechanism to generate the individual rigidifying loads.

43. The method of claim 42, wherein the compressible element is a Belleville spring stack.

44. the payload interface end of the end effector includes a socket drive mechanism, the payload further includes a torque element on the surface of the payload for receiving torque and for passing the received torque to a torque driven subsystem, the method further comprising: contacting the torque element and a socket of the socket drive mechanism when the grapple fixture is rigidified to the end effector by the grapple mechanism; seating the torque element in a socket of the socket drive mechanism when the grapple fixture is grappled and rigidified; applying a torque to the torque element when the torque element is seated in the socket and when the grapple fixture is rigidified to the end effector by rotating the socket seated on the torque element; 39. The method of claim 38, further comprising:

45. 39. The method of claim 38, wherein the first and second coupling elements each include a plurality of radially arranged teeth and notches, and wherein the teeth of the second coupling element are configured to mate with the notches of the first coupling element and the teeth of the first coupling element are configured to mate with the notches of the second coupling element when the first and second coupling elements are brought together during rigidification of the payload to the end effector.

46. 39. The method of claim 38, wherein the first and second coupling elements are configured to each act as one half of a Hirth coupling when the first and second coupling elements are mated during rigidification of the payload to the end effector.

47. 40. The method of claim 38, further comprising limiting load during grappling using a force torque sensor mounted in a primary load path of the grapple mechanism.

48. 48. The method of claim 47, wherein the force-torque sensor simultaneously measures three axes of force and three axes of moment.

49. 1. A method for robotically transmitting torque to a payload, comprising: capturing the payload with an end effector by grappling a grapple fixture on the payload with a grapple mechanism of the end effector; retracting the grapple mechanism to a target preload position to rigidify the grapple fixture to the end effector; seating a torque element residing on the payload into a socket of a socket drive mechanism of the end effector via relative motion of the payload and the end effector resulting from retraction of the grapple mechanism; sensing that the torque element is seated in the socket of the socket drive mechanism; in response to sensing that the torque element is seated in the socket, applying torque to the torque element by rotating the socket to drive a torque-driven subsystem of the payload connected to the torque element; A method comprising:

50. monitoring an amount of torque applied to the torque element via a torque monitoring device; generating an output at the torque monitoring device when a predetermined target amount of torque is applied; stopping rotation of the socket based on the output of the torque monitoring device.

50. The method of claim 49, further comprising:

51. 51. The method of claim 50, wherein the step of monitoring the amount of torque applied to the torque element includes at least one of counting a number of rotations of the socket and measuring an applied current.

52. The step of seating the torque element present on the payload in the socket comprises: if the socket is misaligned with the torque element, engaging an axial compliance mechanism of the socket drive mechanism, the engaging the axial compliance mechanism comprising passively retracting the socket from a forward position when the socket contacts the misaligned torque element; sensing that the axial compliance mechanism is engaged; in response to sensing that the axial compliance mechanism is engaged, rotating the socket until the socket is aligned with and seated on the torque element; disengaging the axial compliance mechanism when the socket is aligned with the torque element, causing the socket to passively return to the forward position.

50. The method of claim 49, comprising:

53. 53. The method of claim 52, wherein sensing that the axial compliance mechanism is engaged comprises triggering a change in state of a sensing element via passive retraction of the socket from the forward position.

54. 54. The method of claim 53, wherein the sensing element includes a physical switch, and triggering the state change of the sensing element includes causing the state of the physical switch to change from a depressed state to a non-depressed state or from a non-depressed state to a depressed state via a feature on the socket disengaging or engaging, respectively, the physical switch when the socket is retracted from the forward position.

55. 55. The method of claim 54, wherein sensing that the torque element is seated in the socket of the socket drive mechanism includes triggering a second state change of the sensing element when the socket passively returns to the forward position.

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