Engagement and homing sequences for surgical tools with high gear ratios

Abstract

Engagement and homing (E&H) sequences for surgical tools (tools) with high gear ratios are described. Responsive to determining that a tool has been coupled to a robotic arm of a surgical robotic system, an E&H sequence is determined. The sequence is performed, wherein a sub-sequence (for a joint) of the E&H sequence comprises: based on a last known position of the joint, selecting a direction for rotating a drive disk that corresponds to a direction of a closest hard stop of a mechanical assembly (e.g., that includes a gear mesh with a high gear ratio) that halts articulation of the joint. The drive disk is rotated in the direction of the hard stop, and once it has been determined that the hard stop was reached and that a tool disk has engaged with the drive disk, the drive disk is rotated to place the joint in a home position.

Description

ENGAGEMENT AND HOMING SEQUENCES FOR SURGICAL TOOLS WITH HIGH GEAR RATIOSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Patent Provisional Application No. 63 / 720,404 filed on November 14, 2024, which is incorporated by reference herein.TECHNICAL FIELD

[0002] The disclosure relates generally to surgical robotic systems, and more specifically to engagement and homing sequences for surgical tools with high gear ratios.BACKGROUND

[0003] Conventional surgical robotic systems use detachable surgical tools that can be coupled / decoupled to robotic arms of the systems. The robotic arms include actuator driven tool interfaces that mechanically couple to receptacles on the tools. Once a surgical tool is coupled to a robotic arm of a conventional surgical robotic system, the system uses a tool interface of the robotic arm to drive the surgical tool in order to articulate an end effector of the surgical tool. Conventional surgical robotic systems may perform an engagement and homing sequence when coupled to the robotic arm. Delay associated with these sequences can impact outcomes in time critical procedures. Moreover, for a single robotic procedure, a surgical tool may be installed and removed multiple times, thereby compounding the amount time of the medical procedure that is devoted to engagement and homing sequences.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 illustrates an example system architecture of a surgical robotic system, in accordance with one or more embodiments.

[0005] FIG. 2 is an example tool, in accordance with one or more embodiments.

[0006] FIG. 3 is an example view illustrating how a drive interface interfaces with a drive assembly, according to one or more embodiments.

[0007] FIG. 4 is an example of a mechanical assembly that controls a roll joint of an endocutter, according to one or more embodiments.

[0008] FIGs. 5A-5C form an example sequence diagram for selection and performance of an engagement and homing sequence, in accordance with some embodiments.JNJ-050WO / AUR6381WOPCT1 1

[0009] FIG. 6 illustrates some example sub-sequences for engagement and homing of a joint, according to one or more embodiments.

[0010] FIG. 7A is a flowchart for a process for performing an engagement and homing sequence for a tool with a high gear ratio, in accordance with some embodiments.

[0011] FIG. 7B is a flowchart for a process for performing a sub-sequence of an engagement and homing sequence, according to one or more embodiments.DETAILED DESCRIPTION

[0012] The figures and the following description describe certain embodiments by way of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods may be employed without departing from the principles described. Wherever practicable, similar or like reference numbers are used in the figures to indicate similar or like functionality. Where elements share a common numeral followed by a different letter, this indicates the elements are similar or identical. A reference to the numeral alone generally refers to any one or any combination of such elements, unless the context indicates otherwise.

[0013] In accordance with one or more aspects of the disclosure, engagement and homing sequences for surgical tools (tools) with high gear ratios are described. Responsive to determining that a tool has been coupled to a robotic arm of a surgical robotic system, an engagement and homing (E&H) sequence is determined. The E&H sequence includes one or more sub-sequences that are used for engagement and homing of joint(s) of an end effector of the tool. In some embodiments, one or more of the joints may be high friction joints. The surgical robotic system may perform the E&H sequence to engage the tool and place the end effector in a home position. For example, a sub-sequence (for a joint of the tool) of the E&H sequence may comprise: based on a last known position of the joint, selecting a direction for rotating a drive disk that corresponds to a direction of a closest hard stop (of a gear mesh with a high gear ratio) that halts articulation of the joint. The drive disk is rotated in the direction of the hard stop, and once it has been determined that the hard stop was reached and that a tool disk has engaged with the drive disk, the engaged drive disk is rotated to place the joint in a home position.

[0014] FIG. 1 illustrates an example system architecture of a surgical robotic system 100, in accordance with one or more embodiments. As shown in FIG. 1, the surgical robotic system 100 comprises a surgical robot 110, a user console 120, and a control system 130, and that are coupled together via a network 140. Alternative embodiments may include more, fewer, or different components from those illustrated in FIG. 1, and the functionality of each component may be divided between the components differently from the description below. For example, in JNJ-050WO / AUR6381WOPCT1 2some embodiments, some of the functionality of the control system 130 may be performed by the surgical robot 110 and / or some computer system.

[0015] The surgical robot 110 is configured to perform surgical procedures on a patient in accordance with instructions from the user console 120. The surgical robot 110 includes one or more robotic arms (e.g., robotic arm 150) mounted on a surgical platform 160 (e.g., a table or a bed etc.). The robotic arms are shown as table -mounted, but in other configurations, the robotic arms may be mounted in a cart, a ceiling, a sidewall, or other suitable support surfaces.Generally, a user, such as a surgeon or other operator, may be positioned at the user console 120 to remotely manipulate the robotic arms and / or surgical instruments (e.g., teleoperation).

[0016] Some or all of the one or more robotic arms can couple to surgical tools (“tools”) at their distal ends. For example, in FIG. 1 the robotic arm 150 includes a distal end 170 that is coupled to atool 180. The distal end (e.g., the distal end 170) of a robotic arm (e.g., the robotic arm 150) includes a drive assembly that rotates one or more drive disks that are configured to interface with tool disks of a tool (e.g., the tool 180). The drive assembly includes one or more motors that can rotate the drive disks. The drive assembly may also include one or more motor sensors that monitor operating parameters (e.g., torque, current, etc.) of the one or more motors that rotate the one or more drive disks. The motor sensors output motor sensor data describing the operating parameters of the one or more motors. The drive assembly may also include various other sensors (e.g., presence sensor, force sensor, etc.) for monitoring atool (e.g., the tool 180). The drive assembly may be communicatively coupled to the control system 130, and provide data from the sensors to the control system 130. For example, the data may include presence data indicating that the tool has been coupled to one of the one or more robotic arms (e.g., the robotic arm 150), motor sensor data, etc.

[0017] The tool 180 may be manipulated manually, robotically, or both, during the surgery. For example, the tool 180 may be used to enter, view, or manipulate an internal anatomy of the patient. The tool 180 includes an end effector (e.g., endocutter, grasper, scissors, needle driver, monopolar hook, camera, etc.) and a drive interface. An end effector may have one or more joints that can be articulated in one or more degrees of freedom depending on its type (e.g., endocutter v. scissors). And various endocutters may be used to execute a surgical operation such as cutting, grasping, poking, stapling, energy emission, etc. The drive interface includes various mechanical assemblies that are coupled to corresponding tool disks that interface with the drive disks of a drive assembly of the robotic arm 150. Rotation of tool disks (via the drive disks) cause corresponding mechanical assemblies to articulate respective joints of the end effector. The tool disks include features (e.g., receptacles) that couple to features (e.g., protrusions) on the driveJNJ-050WO / AUR6381WOPCT1 3disks, such that rotation of a drive disk causes rotation of the tool disk resulting in articulation of the end effector.

[0018] A mechanical assembly provides a range of motion for a joint over at least one degree of freedom of articulation. Different mechanical assemblies may provide corresponding joints with different ranges of motions over a same or different degrees of freedom. For example, an endocutter may be controlled by a combination of 6 inputs (from a plurality of tool disks) that control a roll position of an end effector that consists of a movable and a fixed jaw, a position of a movable jaw, a knife position, and articulation of the end effector to the left and right. In this embodiment, each joint is controlled using a different mechanical assembly that is driven via one or more corresponding tool disks. In this manner, a joint (e.g., knife position) may be controlled by rotating a tool disk that in turn rotates a mechanical assembly that changes position of the joint. The range of motion of a joint may be based in part on hard stops that halt motion of the joint. A hard stop may be, e.g., a software imposed limit on motion, a physical structure that imposes a limit on motion, or some combination thereof. For example, a mechanical assembly may have a first hard stop and a second hard stop that determine the range of motion the joint. In some cases, a hard stop of one tool disk may be coordinated with motion of a second tool disk. For example, two or more tool disks of a tool 180 may be coupled to share a load for actions such as cutting or clamping by driving both drive disks and the corresponding tool disks in the same direction.

[0019] The drive interface may also include sensors (e.g., one or more position sensors) for monitoring the tool 180. The drive interface includes a tool memory for storing position data (e.g., from the one or more position sensors) of the end effector. The position data is indicative of how some or all of the one or more joints of the end effector are positioned. In this manner, if the tool 180 is decoupled from the robotic arm 150, the tool memory includes a last known position of the end effector prior to the decoupling. The tool memory may also include type data that describes a type of the tool 180. In some embodiments, the tool memory may also include an engagement and homing sequence for the tool 180. The drive interface may be communicatively coupled to the control system 130, and provide position data and / or information in the tool memory to the control system 130.

[0020] Some tools (e.g., the tool 180) may have high gear ratios. A tool with a high gear ratio has an end effector (e.g., endocutter) with a joint whose articulation is controlled in part via at least one a gear mesh that has a gear ratio greater than 1. A gear mesh is part of a mechanical assembly used to articulate a joint. The gear mesh includes an input gear and one or more output gears, where the input gear drives one or more output gears, and a gear ratio describes how many rotations of the input gear cause a single rotation in an output gear. For example, a gear ratio of 8JNJ-050WO / AUR6381WOPCT1 4would have the input gear rotating 8 times to rotate the output gear a single time. A high gear ratio may be used to, e.g., provide the mechanical assembly with more torque to articulate the end effector. Moreover, as the gear ratio increases, a force required to back-drive (i.e., directly adjust a position of the joint) the joint increases. The greater back-driving forces can be beneficial in a surgical context to reduce unintended motion of a joint from external forces while not actively driven by a robotic arm 150 and / or while not coupled to the robotic arm 150.

[0021] In some embodiments, one or more of the joints of a tool may be high friction joints. A high friction joint is a joint with a static friction such that at least 80% of maximum torque of a motor (of the drive assembly) that drives the joint is used to break the static friction of the joint. For example, a motor that drives a joint may output up to 0.5 Nm of torque, and if the motor uses at least 0.4 N-m of torque to break static friction of the joint, the joint may be considered a high friction joint. Due to the high friction, the position of a high friction joint is unlikely to change while the tool is not coupled to a robotic arm. Tools and / or end effectors are further described in detail below with regard to, e.g., FIGs 2-4.

[0022] The user console 120 may be used by a user to control the surgical robot 110. The user console 120 may include, e.g., a seat, pedals, one or more handheld user interface devices (UIDs), and a display configured to display, for example, a view of the surgical site inside a patient. For example, a surgeon may sit in the seat, view the display, manipulate the pedals and / or handheld UIDs to remotely control robotic arms (e.g., the robotic arm 150) and / or tools (e.g., the tool 180) mounted to the distal ends of the robotic arms. The foot pedals may be used to activate various system modes, such as endoscope control and various instrument functions including monopolar and bipolar cautery, without involving surgeon's hands removed from the master UIDs.

[0023] The network 140 provides communication pathways between the user console 120, the control system 130, and the surgical robot 110. The network 140 may refer to direct wired or wireless connections between the robot 110, user console 120, and control system 130, and / or may include one or more local area networks (UANs); one or more wide area networks (WANs); one or more personal area networks (PANs); some other one or more networks that provide communication pathways between the user console 120, the control system 130, and the surgical robot 110; or some combination thereof. The network 140 may include physical media for communicating data from one computing device to another computing device, such as multiprotocol label switching (MPUS) lines, fiber optic cables, cellular connections (e.g., 3G, 4G, or 5G spectra), or satellites. In some embodiments, the network 140 may include Bluetooth or nearfield communication (NFC) technologies or protocols for local communications between computing devices. The network 140 may transmit encrypted or unencrypted data.JNJ-050WO / AUR6381WOPCT1 5

[0024] The control system 130 controls components of the surgical robotic system 100.Communication between the surgical robot 110 and the user console 120 may be through the control system 130, which may translate user input from the user console 120 to robotic control commands and transmit the control commands to the surgical robot 110. The control system 130 may also transmit status and feedback from the surgical robot 110 back to the user console 120. For example, a surgeon seated at the user console 120 can perform surgery using the tools controlled by two master UIDs and foot pedals. The control system 130 translates the surgeon's hand, wrist, and finger movements through the master UIDs into precise real-time movements of the tools. The control system 130 may include one or more input devices and one or more output devices (e.g., displays, speakers, etc.).

[0025] In some embodiments, the control system 130 determines when a tool has been coupled or decoupled to a robotic arm of the surgical robot 110. The control system 130 may use presence data from the robotic arm to determine whether or not a tool is coupled to a robotic arm.

[0026] An engagement and homing (E&H) sequence describes a process to perform to engage tool disks of a tool with corresponding drive disks of a robotic arm and place an end effector of the tool in its home position (i.e., home each joint of the tool). In some embodiments, there are a plurality of different E&H sequences that are each associated with specific types of tools. For example, responsive to determining that a tool (e.g., with a high gear ratio) has been coupled to a robotic arm, the control system 130 can determine an E&H sequence for the tool. In some embodiments, the control system 130 may retrieve (e.g., from the tool memory) the E&H sequence for the tool. In some embodiments, the control system 130 may retrieve from the tool memory of the tool 180 type information for the tool 180 (e.g., identifying the tool as a specific model of endocutter), and use the type information to select an E&H sequence for the tool 180 from an E&H sequence library that includes a plurality of different E&H sequences. The control system 130 may then identify which of the plurality of E&H sequences is for the tool and select it as the E&H sequence. The control system 130 performs the E&H sequence for the tool.

[0027] An E&H sequence includes one or more sub-sequences, where a sub-sequence describes an engagement and homing process for one or more joints of the tool. In some embodiments, a sub-sequence is for a single joint, such that there is a sub-sequence for each joint of the tool. In some embodiments, a sub-sequence may be for multiple joints of the tool. The E&H sequence may specify an order in which the sub-sequences are performed. In some embodiments, some or all of the sub-sequences are performed in series (e.g., if there could be cross talk between the joints if performed at the same time). In other embodiments, some of the sub-sequences can be performed in parallel. Whether particular tool disks are to be driven in series or parallel may be based on, e.g., minimizing a total time to execute the E&H sequence for all of the tool disks,JNJ-050WO / AUR6381WOPCT1 6minimizing potential cross talk between different joints that may occur if the different joints are moved in parallel, or both.

[0028] The surgical robotic system 100 performs an E&H sequence by determining a last known position (e.g., receives the position data from a local memory of the tool) of the end effector of the tool, and then performing each sub-sequence of the E&H sequence. For example, a subsequence (for a joint of the tool) of the E&H sequence may comprise: based on a last known position of the joint, selecting a direction for rotating a drive disk that corresponds to a direction of a closest hard stop that halts articulation of the joint. The drive disk is rotated in the direction of the hard stop, and once it has been determined that the hard stop was reached and that a tool disk has engaged with the drive disk, the drive disk is rotated to place the joint in a home position. Accordingly, by performing the E&H sequence, tool disks are engaged with corresponding drive disks for each of the one or more joints of the tool, and each of the one or more joints are placed in a home position. Some example sub-sequences for engaging and homing a joint are described below with regard to FIG. 6.

[0029] For a joint controlled by a mechanical assembly that includes a gear mesh that has a high gear ratio, performing a sub-sequence drives the tool disk coupled to the gear mesh toward a closest hard stop of the mechanical assembly. In some embodiments, regardless of the gear ratio, performing the sub-sequence drives the tool disk coupled to the gear mesh toward a closest hard stop of the mechanical assembly.

[0030] For a given joint that has a range of motion, the control system 130 may use motor sensor data (e.g., from the drive assembly) to determine whether or not engagement has occurred at a hard stop (e.g., motor current peaks above a threshold amount). This current spike occurs as the motor control feedback mechanism increases the motor torque in response to sensing that disk is not rotating under the current torque. Alternatively, engagement may be detected based on position and / or velocity data indicating that the drive disk has stopping turning. Engagement describes when features on the tool disk and features on the drive disk are fully locked together. For example, at the start of the sequence the drive disk, which is initially not engaged, will begin rotating without rotating the tool disk and / or rotate the tool disk at different speed than the drive disk. Once engaged, the drive disk and the tool disk rotate in synchronization, such that rotating the drive disk some amount causes the tool disk to rotate a same amount. Responsive to detecting engagement at the hard stop (i.e., when the spike in motor current is observed), the control system 130 may instruct the drive assembly to drive the joint to a home position. In some embodiments, the home position may be a position at a middle of the range of motion of the joint. In other embodiments, the home position may be at some other position within the range of motion.JNJ-050WO / AUR6381WOPCT1 7

[0031] In some embodiments, a tool may have been positioned, prior to coupling to a robotic arm, such that the end effector is positioned for some or all of its joints (e.g., any that include gear meshes with high gear ratios) close to corresponding hard stops. In some embodiments, positioning the end effector such that one or more its joints are close to hard stops may be done, e.g., as part of the manufacturing process of a tool and / or prior to decoupling the tool from the robotic arm. For example, responsive to receiving a decoupling instruction (e.g., from a user of the user console 120), the control system 130 may instruct a drive assembly to position some or all of the joints close (e.g., a hard stop can be reached in less than one rotation of the tool disk) to hard stops. The position (i.e., position data) of the tool may then be stored to the tool memory prior to decoupling the tool from the robotic arm. Positioning a joint close to a hard stop can be particularly helpful for a joint that includes a gear mesh with a high gear ratio (which relative to a same joint with a low gear ratio would take longer to engage and home if starting from a same position). Moreover, as the total distance a joint travels for engagement and homing is reduced, it often results in faster engagement and homing than, e.g., arbitrarily always driving to a particular hard stop regardless of last known position.

[0032] In some embodiments, after having positioned a joint of an end effector close to a hard stop and saving that position to the memory of the tool at the end of manufacturing, the position of the end effector is physically restrained with a temporary device (e.g. removable snap feature or breakable tack adhesive) to prevent motion during shipping and handling. This physical restraint can later be removed before a first use of the tool.

[0033] In some embodiments, the E&H sequence may include one or more sub-sequences for high friction joints. In these cases, a sub-sequence may be such that its performance directly moves the high friction joint toward a home position (i.e., without first traveling to a closest hard stop). For example, performance of the sub-sequence may cause the control system 130 to instruct a drive assembly to apply a particular amount of force to a driver disk controlling the high friction joint, where the force is in the direction of a home position. Because of the high friction, a detectable spike in the drive motor current is expected when the disks engage due to the resistance from friction causing the motor to output additional torque even prior to reaching the hard stop. Once engaged, the control system 130 instructs the drive assembly to move the joint to the home position (e.g., from the last known position of the joint).

[0034] The control system 130 may generate a notification indicating that a tool has been coupled or decoupled from a robotic arm. For example, once all of tool disks of the tool are successfully engaged with corresponding drive disks, and an end effector of the tool is in the home position, the control system 130 may generate a notification indicating that the tool isJNJ-050WO / AUR6381WOPCT1 8coupled to the robotic arm and ready for use. The control system 130 may instruct one or more displays and / or the user console 120 to present the notification.

[0035] Note that in some embodiments, some of the functionality of the control system 130 may be performed by other components of the surgical robotic system 100. For example, in some embodiments, a robotic arm (e.g., the robotic arm 150) may include functionality to detect tool presence, determine an E&H sequence for the tool, and perform the E&H sequence. The robotic arm may then notify the control system 130 and / or the user console 120 that the tool is homed and ready for use.

[0036] FIG. 2 is an example tool 200, in accordance with one or more embodiments. The tool 200 is an embodiment of the tools (e.g., the tool 180) described above with FIG. 1. The tool 200 includes an end effector 210, a shaft 220, and a drive interface 230. A distal end of the tool 200 includes the end effector 210, and a proximal end of the tool 200 includes the drive interface 230. Alternative embodiments may include more, fewer, or different components from those illustrated in FIG. 2, and the functionality of each component may be divided between the components differently from the description below.

[0037] The tool 200 is an example of an endocutter. An endocutter may be configured to divide and seal tissue. Put another way, an endocutter may be configured to cut and staple tissue with motion provided by a knife or firing joint. The endocutter may be used to cut and staple tissue in a variety of surgical procedures, including bariatric, thoracic, colorectal, gynecologic, urologic, and general surgery. Common clinical use scenarios include reshaping organs, the removal or repair of organs, tissue fixation, dissection, or the creation of anastomoses (or any combination of these).

[0038] The end effector 210 is a device that a surgical robot (e.g., the surgical robot 110) may use to interact with the environment (e.g., operate on a patient). In FIG. 2, the end effector 210 is part of an endocutter that includes a jaw 240A and a jaw 240B, collectively referred to as “jaws 240.” Mechanical assemblies of the tool 200 control articulation of four joints, that respectively control, roll 250, open / close of the jaws 240 (e.g., the jaw 240B may be controllable and the jaw 240A may be fixed), articulation of the jaws 240, and a knife. The endocutter may be implemented such that as the knife moves forward, forming staples, which the endocutter uses to seal the tissue. Some or all of the positions may be determined relative to a tool axis 260. Some embodiments of an endocutter are further described in U.S. Patent Application Publication No.2024 / 0308076, which is herein incorporated by reference in its entirety. While in FIG. 2, the end effector 210 is part of an endocutter, in other embodiments, the tool 200 may of some other type. For example, the end effector 210 may be some other surgical instrument, such as jaws, a cuttingJNJ-050WO / AUR6381WOPCT1 9tool, an endoscope, spreader, implant tool, stapler, etc. FIG. 2 includes an endocutter having a combination of two or more of these instruments such as a cutting tool, jaws, and stapler.

[0039] The shaft 220 couples the end effector 210 to the drive interface 230. The shaft 220 guides portions of the mechanical assemblies to their corresponding joints at the end effector 210. The shaft 220 may be tubular in shape and include one or more channels. The one or more channels guide the portions of the mechanical assemblies from the drive interface 230 to the end effector 210. The shaft 220 may be formed of plastic, metal, or another durable material.

[0040] The drive interface 230 applies adjustments to the mechanical assemblies in order to articulate joints of the end effector 210. The drive interface 230 includes tool disks (that may be rotated). The tool disks are not visible in FIG. 2 as they are located on the occluded side of the drive interface 230. The tool disks are further described below with regard to FIG. 3. Each tool disk is coupled to a different mechanical assembly which controls articulation of a corresponding joint (or in some cases joints), such that rotation of a tool disk drives a mechanical assembly in order to articulate a corresponding joint. The tool disks may be formed of plastic or another durable material. A mechanical assembly provides a range of motion for its corresponding joint over at least one degree of freedom of articulation. And different mechanical assemblies may provide different ranges of motion over same or different degrees of freedom. A range of motion of a joint is based in part on hard stops that set a lower bound and an upper bound for the range of motion. In FIG. 2, the tool 200 includes at least one mechanical assembly that includes a gear with a high gear ratio. For example, the mechanical assembly that articulates the roll 250 of the end effector 210 may include a gear mesh with a gear ratio of at least 4.

[0041] The drive interface 230 monitors various parameters of the tool 200. The drive interface 230 may include one or more position sensors (e.g., position sensor 270), and a tool memory 280. A position sensor monitors a position of a portion of a mechanical assembly (that articulates a joint) in the drive interface 230, where the monitored position is indicative of a position of the joint at the end effector 210. For example, there may be a position sensor in the drive interface 230 for some or all of the joints, such that each position sensor generates position data indicative of a position of the joint it is configured to monitor. In some embodiments, there may be a position sensor in the drive interface 230 for joints with high gear ratios, and other joints may or may not be monitored with position sensors. A position sensor may be, e.g., an optical encoder, hall effect sensor, or some other sensor for determining position. The position data from each of the one or more position sensors may be stored in the tool memory 280. In some embodiments, a processor (not shown) on in the drive interface 230 periodically stores the position data in the tool memory 280 while the tool 200 is coupled to a robotic arm. The position data is provided to the robotic arm and / or the control system 130. In some embodiments, the robotic arm and / or theJNJ-050WO / AUR6381WOPCT1 10control system 130 store the position data in the tool memory 280. In this manner, if the tool 200 is decoupled from the robotic arm, the memory includes a last known position of some (e.g., a high gear ratio joint) or all of the joints of the end effector. The tool memory 280 may also include type data that describes a type of the tool 200. In some embodiments, the tool memory 280 may also include an E&H sequence for the tool 200. The drive interface 230 may be communicatively coupled to the control system 130, and provide position data and / or information (e.g., type data, E&H sequence.) in the tool memory 280 to the control system 130.

[0042] FIG. 3 is an example view 300 illustrating how a drive interface 310 interfaces with a drive assembly 320, according to one or more embodiments. The drive assembly 320 is an embodiment of the drive interface described above with regard to FIG. 1, and the drive interface 310 is an embodiment of the drive interface described above with regard to FIGs. 1 and 2. For example, the drive interface 310 may be an embodiment of the drive interface 230 of the tool 200. Alternative embodiments may include more, fewer, or different components from those illustrated in FIG. 3, and the functionality of each component may be divided between the components differently from the description below.

[0043] The drive interface 310 applies adjustments to mechanical assemblies in order to articulate joints of an end effector (not shown) of the tool. The mechanical assemblies are adjusted by rotating a corresponding tool disk. In FIG. 3, there are six tool disks (e.g., tool disk 330), and each tool disk is exposed on an outside surface of the drive interface 310. In other embodiments, there may be some other number of tool disks. Each tool disk is coupled to a different mechanical assembly which controls articulation of a corresponding joint (or in some cases multiple joints). In this manner, rotation of one or more tool disks can drive a mechanical assembly in order to articulate a joint. For example, the tool disk 330 may control a roll position of an endocutter, another tool disk may control a position of a jaw (e.g., the jaw 240A) of the endocutter, etc. A tool disk may be rotated in a particular direction (e.g., clockwise or anticlockwise) until a hard stop of the corresponding mechanical assembly is reached.

[0044] The drive assembly 320 is configured to interface with the drive interface 310. The drive assembly 320 includes drive disks (e.g., drive disk 340). Some or all of the drive disks are configured to interface with corresponding tool disks on a tool. In the illustrated example, each drive disk interfaces with a corresponding tool disk. For example, when coupled together, the drive disk 340 interfaces with the tool disk 330.

[0045] Each drive disk is exposed on an outside surface of the drive assembly 320 and is designed to engage (e.g., to securely fasten via snap, friction, or other mating features) a corresponding tool disk of the drive interface 310, to enable direct torque transfer between theJNJ-050WO / AUR6381WOPCT1 11two. For example, some or all of the tool disks may include features (e.g., receptacle) that facilitate coupling to corresponding mating features (protrusion) of drive disks.

[0046] For example, in FIG. 3 the drive disk 340 is designed to engage with the tool disk 330. Note that engagement describes when a tool disk and a drive disk are fully locked together. If the drive disk 340 is not fully engaged with the tool disk 330, for every revolution of the drive disk 340, the tool disk 330 may rotate some other amount or not at all. In contrast, once engaged, the drive disk 340 and the tool disk 330 rotate in sync, such that rotating the drive disk 340 an amount causes the tool disk 330 to rotate an equal amount. As described above with regard to FIG. 1, an E&H sequence may be used to ensure engagement of each of the tool disks to their corresponding drive disk and put the end effector in a home position (i.e., each of the joints are in their respective home position).

[0047] In some cases, a tool may include two or more tool disks that are coupled to share a load, such as for performing a cutting or clamping action. In such situations, a hard stop for one tool disk may be caused by a state of the coupled tool disk rather than a separate physical constraint. For example, if two drive disks are signaled to move in opposing directions, then when a first one of the drive disks engages its corresponding first tool disk, the continued turning of that first tool disk will counter any attempted turning of the other (second) tool disk and thus becomes a physical constraint to the second drive disk. This condition serves to enable or helps the second drive disk to engage with its corresponding second tool disk. In other words, as soon as one of the two or more actuators engages (its drive disk engages a corresponding tool disk), it creates a constraint for the other tool disk.

[0048] FIG. 4 is an example of a mechanical assembly 400 that controls a roll joint of an endocutter, according to one or more embodiments. For example, the mechanical assembly 400 may be an embodiment of the mechanical assembly that controls the roll 250 of the end effector 210. Alternative embodiments may include more, fewer, or different components from those illustrated in FIG. 4, and the functionality of each component may be divided between the components differently from the description below.

[0049] The mechanical assembly 400 includes a roll shaft 410. The roll shaft 410 is coupled to and driven by a tool disk 420. The tool disk 420 is coupled to the roll shaft 410 along with a worm gear 430 in order to drive a roll gear 440. The gear mesh formed between the roll gear 440 and the worm gear 430 has a high gear ratio, such that it takes more than one rotation of the worm gear 430 to rotate the roll gear 440 a single time. For example, in this example, the gear ratio may be 4, 8, or some other number greater than 1. The roll gear 440 provides the motion to the roll joint in either the clockwise or counterclockwise direction depending on the rotation ofJNJ-050WO / AUR6381WOPCT1 12the tool disk 420. The roll joint has a range of motion that is bounded by at least one hard stop (e.g., hard stop 450).

[0050] FIGs. 5A-5C form an example sequence diagram 500 for selection and performance of an E&H sequence, in accordance with some embodiments. The sequence diagram 500 includes the tool 180, the robotic arm 150, the control system 130, and the user console 120. Alternative embodiments may include more, fewer, or different interactions from those illustrated in FIGs.5A-5C, and the steps may be performed in a different order from that illustrated in FIGs. 5A-5C.

[0051] The robotic arm 150 gathers 505 presence data from one or more presence sensors indicating that the tool 180 has coupled to a drive interface of the robotic arm 150. The robotic arm 150 provides 510 the presence data to the control system 130.

[0052] The control system 130 determines 515 that the tool 180 has been coupled to the drive interface using the presence data. Responsive to determining that the tool 180 has been coupled to the robotic arm 150 (specifically the drive interface of the robotic arm 150), the control system 130 determines 520 a last known position of an end effector of the tool 180. The control system 130 retrieves from a tool memory of the tool 180 position data with a most recent time stamp that is indicative of positions of each of the one or more joints of the tool, these positions are collectively referred to as a last known position of the end effector.

[0053] The control system 130 determines 525 an E&H sequence for the tool 180. The E&H sequence describes a process to perform to engage each tool disk of the tool 180 with corresponding drive disks of the robotic arm 150, and place each joint of the end effector in its home position, thereby, placing the end effector in its home position. The E&H sequence includes N sub-sequences, where N is an integer. The E&H sequence includes an order in which the N sub-sequences are to be performed. A particular sub-sequence of the E&H sequence may be referred to as sub-sequencei where “i” is an index value that can range from 1 to N. In some embodiments, a particular sub-sequence is for a single joint of the end effector. In other embodiments, a sub-sequence is for multiple joints of the end effector. In some embodiments, the control system 130 may retrieve from the tool memory of the tool 180 the E&H sequence for the tool 180. In some embodiments, the control system 130 may retrieve from the tool memory type information of the tool 180, and use the type information to select the E&H sequence for the tool 180 from a plurality of different E&H sequences.

[0054] In some cases, the tool memory may provide information about certain characteristics of the tool 180. For example, the control system 130 may use tool memory information to determine whether two (or more) tool disks in the surgical tool 180 act in concert to impart end effector movement (or share their load), whether one or more movements of the end effector are subject to hard stops or physical constraints, what are the ranges of movement of the end effector,JNJ-050WO / AUR6381WOPCT1 13what actuators will be used by the surgical tool 180, and stored positions or calibration values such as a home position of a tool disk or a range of acceptable positions, e.g., 290 degrees + / - 4 degrees.

[0055] The control system 130 determines 530 closest hard stop(s) for joint(s) of a sub-sequencei of the E&H sequence. The control system 130 determines positions of the joint(s) from the last known position of the end effector. The control system 130 selects for each of the joint(s) a corresponding hard stop (of the mechanical assembly that articulates the joint) that is closest to the determined position of the joint. The control system 130 instructs 535 the robotic arm 150 to drive the joint(s) of the of a sub-sequence to the selected corresponding hard stop(s).

[0056] The robotic arm 150 performs 540 the instructions. For example, robotic arm 150 uses motor(s) to drive driver disk(s) (of the driver assembly) in order to rotate corresponding tool disk(s) of the joint(s) in a direction that moves the joint(s) toward the closest hard stop(s). One or more motor sensors of the robotic arm 150 monitor one or more parameters of the motor(s) that are driving the tool disk(s). The robotic arm 150 provides 545 motor sensor data from the one or more motor sensors to the control system 130.

[0057] The control system 130 determines 550 engagement between the tool disk(s) and corresponding drive disk(s) using the motor sensor data. For example, for a given tool disk-drive disk pair the control system 130 may monitor the motor current supplied to the motor driving the drive disk, and once the current peaks above some threshold amount (indicative of hitting a hard stop), the control system 130 considers there to be engagement between the tool disk-drive disk pair.

[0058] In another embodiment, the control system 130 may determine 550 engagement based on the velocity or speed of the motor dropping below one or more threshold values indicative of engagement (because at that point the motor is constrained from further movement in the direction towards the hard stop). For example, when the control system 130 detects the speed of the drive disk (or the speed of its actuator motor) has dropped to (e.g., below) a velocity threshold, the control system 130 can detect that engagement has occurred between that drive disk and its corresponding tool disk.

[0059] Once engaged, the control system 130 provides 555 instructions to the robotic arm 150 to home the joint(s) of the sub-sequencei. The instructions include a home position (e.g., middle of range of motion) for each joint of the sub-sequencei. The robotic arm 150 performs 560 the instructions and homes the joint(s) of the sub-sequencei. Once the joint(s) of the sub-sequencei have been homed, the robotic arm 150 provides 565 a notice of completion to the control system 130. The notice of completion informs the control system 130 that the joints of the sub-sequencei are in their respective home positions.JNJ-050WO / AUR6381WOPCT1 14

[0060] In some cases, the control system 130 may track rotational position and rotate the drive disk at different speeds depending on the expected distance from the home position. For example, when the distance is greater than a predetermined threshold, the control system may rotate the drive disk relatively rapidly, and then in response to the difference becoming smaller than the threshold (implying that the drive disk is nearing the home position) the control system 130 may slow the rotation.

[0061] The control system 130 determines 570 whether all sub-sequences of the E&H sequence have been performed. If not, the control system 130 may increments 575 the sub-sequence such that i= i+1, and steps 530-565 repeat for the next sub-sequence of the E&H sequence. In other embodiments, some other index value is chosen for a sub-sequence that has not been previously performed. Once all of the sub-sequences of the E&H sequence are performed, the control system 130 generates 580 a completion notification. The completion notification indicates that that the end effector is ready for use. The control system 130 provides 585 the completion notification to the user console 120. And the user console 120 may present 590 (e.g., via a display) the completion notification to a user.

[0062] FIG. 6 illustrates some example sub-sequences for engagement and homing of a joint, according to one or more embodiments. FIG. 6 illustrates four different sub-sequences, specifically, sub-sequence 605, sub-sequence 610, sub-sequence 615, and sub-sequence 620. The joint has a range of motion that is bounded by hard stop 625 and a hard stop 630, and the joint has a home position 635 within the range of motion. In FIG.6, the home position 635 is in a middle of the range of motion. In other embodiments, the home position 635 is at some other position within the range of motion. The joint may be a joint that includes a gear mesh having a high gear ratio.

[0063] In the sub-sequence 605, the joint has an initial joint position 640. The initial joint position 640 is a last known position of the joint (e.g., determined from position data on a tool memory of the tool). The initial joint position 640 is closest to the hard stop 625, as such, the sub-sequence 605 drives the joint to the hard stop 625. Once engagement has been determined (e.g., using motor sensor data), the joint is then moved to the home position 635. The subsequence 610 is substantially the same as the sub-sequence 605, except that the starting joint position (joint position 645) is closer to the hard stop 630 than the hard stop 625. As such, the joint is driven toward the closet hard stop, i.e., the hard stop 630, and once engagement has been determined, the joint is moved to the home position 635.

[0064] In this manner, the sub-sequences 605, 610 select a minimum distance to articulate the joint in order engage and home the joint. As such, the time it takes to engage and home the jointJNJ-050WO / AUR6381WOPCT1 15is also minimized. This is particularly useful for joints with high gear ratios which take more than a single revolution of a drive disk to drive the tool disk for the joint a single revolution.

[0065] In the sub-sequence 615 , the j oint has an initial j oint position 650 that is close to one of the hard stops. In this example, it is close to the hard stop 625, but in other embodiments, it may be close to the hard stop 630. In this example, the joint was placed in the initial joint position 650 prior to decoupling the tool from a robotic arm, so that when the tool is later coupled to a robotic arm the initial joint position is close to a hard stop, thereby, further minimizing the distance (and time) it takes to engage and home the joint. In some embodiments, an initial joint position may be “close” to a hard stop if the joint can reach the hard stop in less than one rotation of the tool disk.

[0066] The sub-sequence 620 is for an embodiment of a high friction joint. In a high friction joint there is enough friction in the mechanical assembly that it is very unlikely to move unless it is actively driven by a drive assembly of the robotic arm. As such, a force can be applied to the joint in the direction of the home position 635. As the joint is a high friction joint in this example, the applied force would result in minimal motion of the high friction joint. But once a force threshold is exceeded the tool disk-drive disk pair for the high friction joint engage, and the applied force can be increased to move the high friction joint to the home position 635 without having to drive it toward one of the hard stops. In this manner, for high friction joints, the subsequence 620 further reduces time in the engagement and homing of the high friction joint.

[0067] The sub-sequences 605, 610, 615, and 620 can be used in E&H sequences to reduce time used for engagement homing of a tool. For example, an endocutter is an instrument that typically has multiple removals and reinstallations during a single robotic procedure to replace spent stapler cartridges and therefore undergoes the engaging and homing process repeatedly during a procedure. Long engaging and homing processes (e.g., for joints with high gear ratios) are compounded in such a use case. Using some or all of the sub-sequences 605, 610, 615, and 620 and / or variations thereof, reduces the engagement and homing time for the tool, and would allow a surgeon to use the tool more quickly after being reinstalled on a robot arm.

[0068] FIG. 7A is a flowchart for a process 700 for performing an E&H sequence for a tool with a high gear ratio, in accordance with some embodiments. Alternative embodiments may include more, fewer, or different steps from those illustrated in FIG. 7A, and the steps may be performed in a different order from that illustrated in FIG. 7A. These steps may be performed by a surgical robotic system (e.g., the surgical robotic system 100). In some embodiments, the process 700 may be performed responsive to determining that a tool has been coupled to the robotic arm of the surgical robotic system.JNJ-050WO / AUR6381WOPCT1 16

[0069] The surgical robotic system determines 705 an E&H sequence for an end effector of a tool. The E&H sequence includes N sub-sequences, where N is an integer. The E&H sequence may include an order in which the N sub-sequences are to be performed. A control system (e.g., the control system 130) of the surgical robotic system retrieves from the tool memory position data with a most recent time stamp that is indicative of positions of some or all of the one or more joints of the end effector, these positions are collectively referred to as a last known position of the end effector. The E&H sequence may be retrieved from the tool memory, from an E&H sequence library based on tool type (e.g., type information), or both.

[0070] The surgical robotic system selects 710 a sub-sequence i, of the E&H sequence, associated with one or more joints of the end effector. For example, the surgical robotic system (e.g., via the control system 130) may select a sub-sequence (e.g., i=l) that the E&H sequence indicates is to be performed first.

[0071] The surgical robotic system performs 715 the sub-sequencei to engage and home the one or more joints. Step 715 is described in detail below with regard to FIG. 7B.

[0072] The surgical robotic system determines 720 whether all sub-sequences of the E&H sequence have been performed. If not, the surgical robotic system increments 730 the subsequence such that i= i+1, and the process moves to step 710. Once all of the sub-sequences of the E&H sequence are performed, the surgical robotic system generates a completion notification that indicates that that the end effector is ready for use. The surgical robotic system presents 725 (e.g., via a display of a user console 120) the completion notification to a user.

[0073] FIG. 7B is a flowchart for a process 750 for performing a sub-sequence of an E&H sequence, according to one or more embodiments. For example, the process 750 may be an embodiment of a process performed as part of step 715 in FIG. 7A. Alternative embodiments may include more, fewer, or different steps from those illustrated in FIG. 7B, and the steps may be performed in a different order from that illustrated in FIG. 7B. These steps may be performed by a control system (e.g., the control system 130) of a surgical robotic system (e.g., the surgical robotic system 100).

[0074] The sub-sequence may be for engaging and homing a joint of an end effector of a tool that is coupled to a robotic arm of the surgical robotic system. The tool includes a tool disk associated with the joint, such that rotation of the tool disk rotates a gear mesh to articulate the joint in one or more degrees of freedom. In some embodiments, the gear mesh has a gear ratio that is greater than 1.

[0075] The control system, based on a last known position of the joint, selects 755 from a plurality of possible directions within the one or more degrees of freedom, a direction for rotating a drive disk (of the robotic arm) that corresponds to a direction of a closest hard stop of aJNJ-050WO / AUR6381WOPCT1 17mechanical assembly that halts articulation of the joint. For example, the control system may determine a position of the joint from the last known position of the end effector. The control system may select a hard stop that is closest to the determined position of the joint.

[0076] The control system instructs 760 a drive assembly (of the robotic arm) to rotate the drive disk in the direction of the hard stop. The drive assembly rotates the drive disk, which in turn rotates a tool disk that drives the gear mesh towards the hard stop.

[0077] The control system determines 765 that the mechanical assembly has reached the hard stop and that the tool disk has engaged with the drive disk. For example, the control system may monitor motor sensor data from one or more motor sensors monitoring one or more motors that drive the drive disk. The control system uses the motor sensor data to determine that the tool disk has engaged with the drive disk. For example, once a current supplied to the one or more motors peaks above a threshold amount for at least a threshold amount of time (indicative of hitting a hard stop and being engaged), the control system determines that the tool disk has engaged with the drive disk.

[0078] The control system instructs 770 the drive assembly to rotate at least the drive disk to place the joint in a home position. For example, in embodiments, where the joint is driven solely by the drive disk, the drive disk may be rotated to place the joint in the home position. In contrast, in embodiments, where the joint is controlled by multiple drive disks, all of the multiple drive disks are engaged and then homed (using the process 750), in order to place the joint in the home position. Once the joint has been homed, the drive assembly sends a notification to the control system.

[0079] The control system receives 755 the notification from the drive assembly that the joint is in the home position. Referring back to FIG. 7A, in some embodiments, once the message is received, the control system may proceed to step 720.

[0080] The foregoing description of the embodiments has been presented for illustration; it is not intended to be exhaustive or to limit the patent rights to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible considering the above disclosure.

[0081] Some portions of this description describe the embodiments in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss ofJNJ-050WO / AUR6381WOPCT1 18generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof.

[0082] Any of the steps, operations, or processes described herein may be performed or implemented with one or more hardware or software modules, alone or in combination with other devices. In one embodiment, a software module is implemented with a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all the steps, operations, or processes described.

[0083] Embodiments may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, and / or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a non-transitory, tangible computer readable storage medium, or any type of media suitable for storing electronic instructions, which may be coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability.

[0084] Embodiments may also relate to a product that is produced by a computing process described herein. Such a product may comprise information resulting from a computing process, where the information is stored on a non-transitory, tangible computer readable storage medium and may include any embodiment of a computer program product or other data combination described herein.

[0085] Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the patent rights. It is therefore intended that the scope of the patent rights be limited not by this detailed description, but rather by any claims that issue on an application based hereon.Accordingly, the disclosure of the embodiments is intended to be illustrative, but not limiting, of the scope of the patent rights, which is set forth in the following claims.JNJ-050WO / AUR6381WOPCT1 19What is claimed is:1. A surgical robotic system comprising:a tool that includes a drive interface that is coupled to an end effector, and the drive interface includes a tool disk whose rotation rotates a gear mesh of a mechanical assembly in order to articulate a joint of the end effector in a degree of freedom;a robotic arm for positioning the tool, the robotic arm including a drive assembly that rotates a drive disk that is configured to interface with the tool disk; and a control system including a processor and a non-transitory computer readable storage medium having instructions encoded thereon that, when executed by the processor, cause the control system to perform steps comprising:responsive to determining that the tool has been coupled to the robotic arm, determining an engagement and homing (E&H) sequence for the end effector, and performing the E&H sequence, wherein the E&H sequence includes a sub-sequence that comprises:based on a last known position of the joint, selecting from a plurality of possible directions within the degree of freedom, a direction for rotating the drive disk that corresponds to a direction of a closest hard stop of the mechanical assembly that halts articulation of the joint, instructing the drive assembly to rotate the drive disk in the direction of the hard stop,determining that the mechanical assembly has reached the hard stop and that the tool disk has engaged with the drive disk, andinstructing the drive assembly to rotate one or more drive disks, that include the drive disk, to place the joint in a home position.2. The surgical robotic system of claim 1, wherein the drive interface includes a second tool disk whose rotation rotates a second gear mesh in order to articulate a second joint of the end effector, and the E&H sequence includes a second sub-sequence to home and engage the second joint, and the non-transitory computer readable storage medium further comprises encoded instructions that when executed cause the control system to perform steps comprising: JNJ-050WO / AUR6381WOPCT1 20performing the second sub-sequence in series with the sub-sequence.3. The surgical robotic system of claim 1, wherein the drive interface includes a second tool disk whose rotation rotates a second gear mesh in order to articulate a second joint of the end effector, and the E&H sequence includes a second sub-sequence to home and engage the second joint, and the non-transitory computer readable storage medium further comprises encoded instructions that when executed cause the control system to perform steps comprising:performing the second sub-sequence in parallel with the sub-sequence.4. The surgical robotic system of claim 1, wherein the tool further comprises:one or more position sensors configured to output position data describing a position of the joint; anda memory configured to store the position data;wherein the control system further comprises encoded instructions that when executed cause the control system to perform steps comprising:retrieving position data with a most recent time stamp from the memory, anddetermining from the retrieved position data the last known position of the joint.5. The surgical robotic system of claim 1, wherein the tool further comprises:one or more position sensors configured to output position data describing a position of one or more joints, including the joint, of the end effector;a memory configured to store the position data; anda processor configured to store the position data to the memory.6. The surgical robotic system of claim 1, wherein the gear mesh has a gear ratio that is greater than 1.7. The surgical robotic system of claim 1, wherein the control system further comprises encoded instructions that when executed cause the control system to perform steps comprising:responsive to receiving a decoupling instruction, instructing the drive assembly to position the joint such that the hard stop can be reached in less than one rotation of the tool disk.JNJ-050WO / AUR6381WOPCT1 21

Claims

8. The surgical robotic system of claim 1, wherein the last known position is such that the joint positioned can reach the hard stop in less than one rotation of the tool disk.

9. The surgical robotic system of claim 1, wherein the robotic arm comprises: a sensor configured to monitor operating parameters of a motor, of the drive assembly, that rotates the drive disk,wherein the encoded instructions for determining that the mechanical assembly has reached the hard stop and that the tool disk has engaged with the drive disk further comprises encoded instructions that when executed cause the control system to perform steps comprising:detecting, based on the motor operating parameters, engagement between the tool disk and the drive disk.

10. The surgical robotic system of claim 1, wherein the tool is an endocutter.

11. A method comprising :responsive to determining that a tool has been coupled to a robotic arm, determining an engagement and homing (E&H) sequence for an end effector of the tool, wherein rotation of a tool disk rotates a gear mesh of a mechanical assembly in order to articulate a joint of the end effector in a degree of freedom, wherein the tool disk is rotated by a drive disk of a drive assembly on the robotic arm, and performing the E&H sequence, wherein a sub-sequence of the E&H sequence comprises:based on a last known position of the joint, selecting from a plurality of possible directions within the degree of freedom, a direction for rotating the drive disk that corresponds to a direction of a closest hard stop of the mechanical assembly that halts articulation of the joint, instructing the drive assembly to rotate the drive disk in the direction of the hard stop,determining that the mechanical assembly has reached the hard stop and that the tool disk has engaged with the drive disk, andJNJ-050WO / AUR6381WOPCT1 22instructing the drive assembly to rotate one or more drive disks, that include the drive disk, to place the joint in a home position.

12. The method of claim 11, wherein the tool includes a second tool disk whose rotation rotates a second gear mesh in order to articulate a second joint of the end effector, and the E&H sequence includes a second sub-sequence to home and engage the second joint, and the method further comprises:performing the second sub-sequence in series with the sub-sequence.

13. The method of claim 11, wherein the tool includes a second tool disk whose rotation rotates a second gear mesh in order to articulate a second joint of the end effector, and the E&H sequence includes a second sub-sequence to home and engage the second joint, and the method further comprises:performing the second sub-sequence in parallel with sub-sequence.

14. The method of claim 11, further comprising:retrieving position data with a most recent time stamp from a memory of the tool; and determining from the retrieved position data the last known position of the joint.

15. The method of claim 11, further comprising:responsive to receiving a decoupling instruction, instructing the drive assembly to position the joint such that the hard stop can be reached in less than one rotation of the tool disk.

16. A computer program product comprising a non-transitory computer readable storage medium having instructions encoded thereon that, when executed by a processor of a computer system, cause the computer system to perform steps comprising:responsive to determining that a tool has been coupled to a robotic arm,determining an engagement and homing (E&H) sequence for an end effector of the tool, wherein rotation of a tool disk rotates a gear mesh of a mechanical assembly in order to articulate a joint of the end effector in a degree of freedom, wherein the tool disk is rotated by a drive disk of a drive assembly on the robotic arm, and performing the E&H sequence, wherein a sub-sequence of the E&H sequence comprises:JNJ-050WO / AUR6381WOPCT1 23based on a last known position of the joint, selecting from a plurality of possible directions within the degree of freedom, a direction for rotating the drive disk that corresponds to a direction of a closest hard stop of the mechanical assembly that halts articulation of the joint, instructing the drive assembly to rotate the drive disk in the direction of the hard stop,determining that the mechanical assembly reached the hard stop and that the tool disk has engaged with the drive disk, andinstructing the drive assembly to rotate one or more drive disks, that include the drive disk, to place the joint in a home position.

17. The computer program product of claim 16, wherein the tool includes a second tool disk whose rotation rotates a second gear mesh in order to articulate a second joint of the end effector, and the E&H sequence includes a second sub-sequence to home and engage the second joint, and the computer program product further comprises encoded instructions that when executed cause the computer system to perform steps comprising:performing the second sub-sequence in series with sub-sequence.

18. The computer program product of claim 16, wherein the tool includes a second tool disk whose rotation rotates a second gear mesh in order to articulate a second joint of the end effector in a second degree of freedom, and the E&H sequence includes a second sub-sequence to home and engage the second joint, and the computer program product further comprises encoded instructions that when executed cause the computer system to perform steps comprising:performing the second sub-sequence in parallel with sub-sequence.

19. The computer program product of claim 16, further comprises encoded instructions that when executed cause the computer system to perform steps comprising:retrieving position data with a most recent time stamp from a memory of the tool; and determining from the retrieved position data the last known position of the joint.

20. The computer program product of claim 16, further comprises encoded instructions that when executed cause the computer system to perform steps comprising:JNJ-050WO / AUR6381WOPCT1 24responsive to receiving a decoupling instruction, instructing the drive assembly to position the joint such that the hard stop can be reached in less than one rotation of the tool disk.JNJ-050WO / AUR6381WOPCT1 25

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