Detecting engagement of a surgical tool disk with a tool drive disk in a surgical robotic system

Abstract

After detecting that a surgical tool is attached to a tool drive on a surgical robotic arm, a drive disks is actuated through its respective motor which causes a speed of the drive disk to increase to a non-zero value. During the actuation, the drive disk is determined to be engaged to its respective tool disk in response to detecting the speed of the drive disk or the respective motor has dropped to a threshold without detecting a torque of the respective motor. Other aspects are also described and claimed.

Description

DETECTING ENGAGEMENT OF A SURGICAL TOOL DISK WITH ATOOL DRIVE DISK IN A SURGICAL ROBOTIC SYSTEMThis patent application claims the benefit of the earlier filing date of U.S. provisional application no. 63 / 735,800 filed December 18, 2024.FIELD

[0001] An aspect of the disclosure here relates to surgical robotic systems that detect when a disk of a robotic tool has become engaged with a disk of a tool drive on a surgical robotic arm of the system.BACKGROUND

[0002] Surgical robotic systems give an operator, such as an operating surgeon, the ability to perform certain actions of a surgical procedure using the surgical robotic system. In the surgical robotic system, a surgical tool, such as an endoscope, clamps, cutting tools, spreaders, needles, energy emitters, etc., is mechanically coupled to a robot joint of a surgical robotic arm, so that movement or actuation of the robot joint (which is being controlled by system to follow an operator command) directly causes, for example an expected rotation, pivoting, or linear movement of a part of the tool. Examples include rotation of an endoscope camera, pivoting of a grasper jaw, translation of a needle, closing clamps, adjusting the bend of an endoscope, extending an instrument outside of cannula walls, applying pressure using a clamping tool, as well as other movements and actions.

[0003] Due to the varied nature of surgical procedures, different surgical tools may be selectively attached to the same tool drive on an arm of the surgical robotic system, before and during a surgical procedure. Once a surgical tool has been attached to a tool drive of the arm, in order to avoid equipment malfunctions during an upcoming surgical procedure, it is important that every tool disk of the surgical tool also be successfully “engaged” with its associated drive disk in the tool drive before the surgical tool is used during the surgical procedure. Engagement refers to the interlocking or interaction of a pair of mechanical couplings also referred to as disks, a pair being a mechanical coupling in the surgical tool and an associated one in the tool drive. The engagement of the tool with the tool drive enables the system tocontrol the full range of motion of an active feature accurately and reliably in the tool that is operated by a pair of disks (e.g., opening of a grasper, closing of the grasper, translation of a needle, etc.)SUMMARY

[0004] One aspect of the disclosure here is a method for reporting engagement of a surgical tool with a tool drive of a surgical robotic system. The attachment of a surgical tool to a tool drive on a surgical robotic arm is detected by a processor. The surgical tool comprises one or more tool disks, a transmission, and an end effector. The transmission couples the one or more tool disks to the end effector to transfer motion of the one or more tool disks to motion of the end effector. The tool drive comprises one or more drive disks each being coupled to be actuated by a respective motor. Next, the processor actuates each drive disk through its respective motor which causes a speed of the drive disk or the motor to increase to a non-zero value. During this actuation, the processor determines that the drive disk is engaged to the respective tool disk in response to detecting that the speed of the drive disk or the respective motor has dropped to a speed threshold without detecting a torque of the respective motor. In other words, while the torque could be monitored for other reasons, the monitored torque need not be used for the engagement determination.

[0005] In another aspect, after mechanical engagement of all of the active drive disks has been detected by the processor, the surgical robotic system enters teleoperation mode in which the system allows the various joints of the attached surgical tool to be directly controlled by an operator.

[0006] The above summary does not include an exhaustive list of all aspects of the present disclosure. It is contemplated that the disclosure includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the Claims section. Such combinations may have particular advantages not specifically recited in the above summary.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The various aspects are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to "an" or “one” aspect in this disclosure are not necessarily to the same aspect, and they mean at least one. Also, in the interest of conciseness and reducing the total number of figures, a given figure may be used to illustrate the features of more than one aspect, and not all elements in the figure may be required for a given aspect.

[0008] FIG. 1 is a pictorial view of an example surgical robotic system in an operating arena;

[0009] FIG. 2 is an illustration of a system for detecting engagement of a surgical tool and a tool drive, of a surgical robotic arm;

[0010] FIG. 3 is a block diagram showing a surgical tool, a tool drive, and a control unit;

[0011] FIGs. 4A-4C illustrate different states of a tool disk and a drive disk during an engagement process;

[0012] FIG. 5A is a flow diagram illustrating a process performed by a control unit for engaging a surgical tool with a tool drive;

[0013] FIG. 5B is a flow diagram illustrating another process for a control unit detecting engagement of a tool disk to a drive disk based on one or more operating parameters of an actuator that is driving the drive disk;

[0014] FIG. 5C is a flow diagram illustrating another process for a control unit to detect engagement of a surgical tool with a tool drive of a surgical robotic system; and

[0015] FIG. 6 depicts a block diagram of a feedback loop.DETAILED DESCRIPTION

[0016] In the following description numerous details are set forth to provide a thorough understanding of the various aspects. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

[0017] Referring to FIG. 1, this is a pictorial view of an example surgical robotic system 100 in an operating arena. The surgical robotic system includes a user console 102, a control tower 103, and one or more surgical robotic arms, such as a surgical robotic arm 104, at a surgical platform 105, e.g., a table, a bed, etc. The surgical robotic system 100 can incorporate any number of devices, tools, or accessories used to perform surgery on a patient 106. For example, the surgical robotic system 100 may include one or more surgical tools 107 used to perform surgery. The surgical tool 107 may have an end effector at its distal end (also a distal end of the robotic surgical arm 104 to which the surgical tool 107 is attached), for executing a surgical operation such as cutting, grasping, poking, or energy emission.

[0018] Each surgical tool 107 may be manipulated manually, robotically, or both, during the surgery. For example, the surgical tool 107 may be a tool used to enter, view, or manipulate an internal anatomy of the patient 106. In one aspect, the surgical tool 107 is a grasper that can grasp tissue of the patient. The surgical tool may be controlled manually, directly by a hand of a bedside operator 108; or it may be controlled robotically, via sending electronic commands to actuate movement of the surgical robotic arm 104 to which the surgical tool 107 is attached. The surgical robotic arms 104 are shown as a table-mounted system, but in other configurations the surgical robotic arms may be mounted in a cart, ceiling or sidewall, or in another suitable structural support.

[0019] Generally, a remote operator 109 such as a surgeon may use the user console 102 to remotely manipulate the surgical robotic arms 104 and the attached surgical tools 107, e.g., teleoperation. The user console 102 may be located in the same operating room as the rest of the surgical robotic system 100, as shown in FIG.1. In other environments, however, the user console 102 may be located in anadjacent or nearby room, or it may be at a remote location, e.g., in a different building, city, or country. The user console 102 may comprise a seat 110, foot- operated controls 113, one or more handheld user interface devices, UID 114, and at least one user display 115 that is configured to display, for example, a view of the surgical site inside the patient 106. In the example user console 102, the remote operator 109 is sitting in the seat 110 and viewing the user display 115 while manipulating a foot-operated control 113 and a handheld UID 114 in order to remotely control the surgical robotic arms and the surgical tools 107 (that are mounted on the distal ends of the surgical arms).

[0020] In some variations, the bedside operator 108 may also operate the surgical robotic system 100 in an “over the bed” mode, in which the beside operator 108 (user) is now at a side of the patient 106 and is simultaneously manipulating i) a robotically-driven tool (having an end effector) that is attached to the surgical robotic arm 104, e.g., with a handheld UID 114 held in one hand, and ii) a manual laparoscopic tool. For example, the bedside operator’s left hand may be manipulating the handheld UID to control a surgical robotic component, while the bedside operator’s right hand may be manipulating a manual laparoscopic tool. Thus, in these variations, the bedside operator 108 may perform both robotic-assisted minimally invasive surgery and manual laparoscopic surgery on the patient 106.

[0021] During an example procedure (surgery), the patient 106 is prepped and draped in a sterile fashion to achieve anesthesia. Initial access to the surgical site may be performed manually while the arms of the surgical robotic system 100 are in a stowed configuration or withdrawn configuration (to facilitate access to the surgical site.) Once access is completed, initial positioning or preparation of the surgical robotic system 100 including its surgical robotic arms may be performed. Next, the surgery proceeds with the remote operator 109 at the user console 102 utilizing the foot-operated controls 113 and the UIDs 114 to manipulate the various end effectors and perhaps an imaging system to perform the surgery. Manual assistance may also be provided at the procedure bed or table, by sterile-gowned bedside personnel, e.g., the bedside operator 108 who may perform tasks such as retracting tissues, performing manual repositioning, and tool exchange upon one or more of the surgical robotic arms 104. Non-sterile personnel may also be present to assist the remoteoperator 109 at the user console 102. When the procedure or surgery is completed, the surgical robotic system 100 and the user console 102 may be configured or set in a state to facilitate post-operative procedures such as cleaning or sterilization and healthcare record entry or printout via the user console 102.

[0022] In one aspect, the remote operator 109 holds and moves the UID 114 to provide an input command to move a robot arm actuator 117 in the surgical robotic system 100. The UID 114 may be communicatively coupled to the rest of the surgical robotic system 100, e.g., via a console computer system 116. The UID 114 can generate spatial state signals corresponding to movement of the UID 114, e.g., position and orientation of the handheld housing of the UID, and the spatial state signals may be input signals to control a motion of the robot arm actuator 117. The surgical robotic system 100 may use control signals derived from the spatial state signals, to control proportional motion of the actuator 117. In one aspect, a console processor of the console computer system 116 receives the spatial state signals and generates the corresponding control signals. Based on these control signals, which control how the actuator 117 is energized to move a segment of the surgical robotic arm 104, the movement of a corresponding surgical tool that is attached to the arm may mimic the movement of the UID 114. Similarly, interaction between the remote operator 109 and the UID 114 can generate, for example, a grip control signal that causes a jaw of a grasper of the surgical tool 107 to close and grip the tissue of patient 106.

[0023] Surgical robotic system 100 may include several UIDs 114, where respective control signals are generated for each UID that control the actuators and the surgical tool (end effector) of a respective surgical robotic arm 104. For example, the remote operator 109 may move a first UID 114 to control the motion of an actuator 117 that is in a left robotic arm, where the actuator responds by moving linkages, gears, etc., in that surgical robotic arm 104. Similarly, movement of a second UID 114 by the remote operator 109 controls the motion of another actuator 117, which in turn moves other linkages, gears, etc., of the surgical robotic system 100. The surgical robotic system 100 may include a right surgical robotic arm 104 that is secured to the bed or table to the right side of the patient, and a left surgical robotic arm 104 that is at the left side of the patient. An actuator 117 may include oneor more motors that are controlled so that they drive the rotation of a joint of the surgical robotic arm 104, to for example change, relative to the patient, an orientation of an endoscope or a grasper of the surgical tool 107 that is attached to that arm. Motion of several actuators 117 in the same surgical robotic arm 104 can be controlled by the spatial state signals generated from a particular UID 114. The UIDs 114 can also control motion of respective surgical tool graspers. For example, each UID 114 can generate a respective grip signal to control motion of an actuator, e.g., a linear actuator, which opens or closes jaws of the grasper at a distal end of surgical tool 107 to grip tissue within patient 106.

[0024] In some aspects, the communication between the surgical platform 105 and the user console 102 may be through a control tower 103, which may translate user commands that are received from the user console 102 (and more particularly from the console computer system 116) into robotic control commands that are transmitted to the surgical robotic arms 104 on the surgical platform 105. The control tower 103 may also transmit status and feedback from the surgical platform 105 back to the user console 102. The communication connections between the surgical platform 105, the user console 102, and the control tower 103 may be via wired and / or wireless links, using any suitable ones of a variety of data communication protocols. Any wired connections may be optionally built into the floor and / or walls or ceiling of the operating room. The surgical robotic system 100 may provide video output to one or more displays, including displays within the operating room as well as remote displays that are accessible via the Internet or other networks. The video output or feed may also be encrypted to ensure privacy and all or portions of the video output may be saved to a server or electronic healthcare record system.

[0025] FIG. 2 is an illustration of a subsystem or a part of the surgical robotic system 100, for detecting engagement of a surgical tool 240 to a tool drive 230 of a surgical robotic arm 220. The surgical robotic arm 220 may be one of the surgical robotic arms 104 of surgical robotic system 100 illustrated and discussed with respect to FIG. 1. The control unit 210 may be part of, for example, the control tower. As discussed in more detail herein, control unit may detect the engagement based on one or more motor operating parameters of one or more actuators (e.g., a second actuator 238-j) in the tool drive 230.

[0026] There is a tool drive 230 to which different surgical tools (e.g., surgical tool 240, as well as other detachable surgical tools - not shown) may be selectively attached (one at a time.) This may be done by for example a human user holding the housing of the surgical tool 240 in her hand and moving the latter in the direction of arrow 280 shown until the outside surface of the surgical tool 240 in which there are one or more tool disks (e.g., first tool disk 244-i) comes into contact with the outside surface of the tool drive 230 in which there are one or more drive disks (e.g., first drive disk 234-i). In the example shown, the tool drive 230 is a segment of the surgical robotic arm 220 at a distal end portion of the surgical robotic arm 220. A proximal end portion of the arm 220 is secured to a surgical robotic platform, such as a surgical table that is not shown in Fig. 2 but an example of which may be seen in FIG. 1 described above.

[0027] Control unit 210 is responsible for controlling motion of the various motorized joints in the surgical robotic arm 220 (including the drive disks 234) through which operation of end effector 246 (its position and orientation as well as its surgical function) which mimics that of a user input device is achieved. This is achieved via a mechanical transmission in the surgical tool 240, when the surgical tool 240 has been engaged to transfer force or torque from the tool drive 230. The control unit 210 may be implemented as a programmed processor, for example as part of the control tower 103 of FIG. 1. It may respond to one or more user commands received via a local or remote user input (e.g., joystick, touch control, wearable device, or other user input device communicating via console computer system 116.) Alternatively, the control unit 210 may respond to one or more autonomous commands or controls (e.g., received form a trained surgical machine learning model that is being executed by the control unit 210 or by the console computer system 116), or a combination thereof. The commands dictate the movement of robotic arm 220 and operation of its attached end effector 246.

[0028] The end effector 246 may be any surgical instrument, such as jaws, a cutting tool, an endoscope, spreader, implant tool, etc. Different surgical tools each having different end effectors can be selectively attached (one at a time) to robotic arm 220 for use during a surgical or other medical procedure. The end effector 246 depicted in the example of FIG. 2 is jaws located at a distal end of the surgical tool240 and that may be retracted into, or extend out of, a cannula as shown (e.g., a thin tube that may be inserted into a patient undergoing a surgical procedure).

[0029] The robotic arm 220 includes a tool drive 230, in which there are one or more actuators, such as actuator 238-j . Each actuator may be a linear or rotary actuator that has one or more respective electric motors (e.g., a brushless permanent magnet de motor) whose drive shaft may be coupled to a respective drive disk 234 through a transmission (e.g., a gear train that achieves a given gear reduction ratio - not shown). The tool drive 230 includes one or more drive disks 234 that may be arranged on a planar or flat surface of the tool drive 230, wherein the figure shows several such drive disks that are arranged on the same plane of the flat surface. Each drive disk 234 is exposed on the outside surface of the tool drive 230 and is designed to mechanically engage (e.g., to securely fasten via snap, friction, or other mating features) a mating tool disk 244 of the surgical tool 240, to enable direct torque transfer between the two. This may take place once for example a planar or flat surface of the surgical tool 240 and corresponding or mating planar or flat surface of the tool drive 230 are brought in contact with one another.

[0030] Furthermore, a motor driver circuit (not shown but that may for example be installed in the tool drive 230 or elsewhere in the surgical robotic arm 220) is electrically coupled to the input drive terminals of a constituent motor of one or more of the actuators 238. The motor driver circuit manipulates the electrical power drawn by the motor in order to regulate for example the speed of the motor or its torque, in accordance with a motor driver circuit input, which can be set or controlled by control unit 210, which results in the powered rotation of the associated drive disk 234.

[0031] When the second drive disk 234-j is mechanically engaged to its corresponding second tool disk 244-j, the powered rotation of the second drive disk 234-j causes the second tool disk 244-j to accurately and reliably rotate, e.g., the two disks may rotate as one, thereby imparting motion on, for example, linkages, gears, cables, chains, or other transmission means within the surgical tool 240 for controlling the movement and operation of the end effector 246 which may be mechanically coupled to the transmission means.

[0032] Different surgical tools may have different numbers of tool disks based on the types of movements and the number of degrees of freedom in which the movements are performed by their end effectors, such as rotation, articulation, opening, closing, extension, retraction, applying pressure, etc.

[0033] Furthermore, within the surgical tool 240, more than one tool disk 244 may contribute to a single motion of the end effector 246 to achieve goals such as load sharing by two or more motors that are driving the mating drive disks 234, respectively.

[0034] In another aspect, within the tool drive 230, there may be two or more motors whose drive shafts are coupled (via a transmission) to rotate the same output shaft (or drive disk 234), to share a load.

[0035] In yet another aspect, within the surgical tool 240, there may be a transmission which translates torque from two drive disks, first drive disk 234-i and second drive disk 234-j (via respective tool disks 244) for performing complimentary actions in the same degree of freedom, e.g., the first drive disk 234-i rotates a drum within the housing of the surgical tool to take in one end of a cable, and a second drive disk 234-j rotates another drum within the housing of the surgical tool to take in the other end of the cable. As another example, the extension and the shortening of an end effector along a single axis may be achieved using two tool disks, for example first tool disk 244-i and second tool disk 244-j, one to perform the extension and another to perform the retraction, for example via different cables. This is in contrast to an effector that also moves in one degree of freedom (e.g., extension and shortening longitudinally along a single axis of movement) but that only needs a single tool disk to control its full range of movement. As another example, an effector that moves in multiple degrees of freedom (e.g., such as a wristed movement, movement along multiple axes, activation of an energy emitter in addition to end effector movement, etc.) may necessitate the use of several tool disks (each being engaged to a respective drive disk). In another type of surgical tool 240, a single tool disk 244 is sufficient to perform both extension and retraction motions, via direct input (e.g., gears). As another example, in the case of the end effector 246 being jaws, two or more tool disks 244 may cooperatively control the motion of the jaws, for load sharing, as discussed in greater detail herein.

[0036] In some aspects, when surgical tool 240 is first attached to or installed on tool drive 230 such that the tool disks are brought substantially into coplanar and coaxial alignment with corresponding drive disks (though the tool and drive disks are perhaps not yet successfully engaged), control unit 210 initially detects the attachment, by for example detecting the type of the surgical tool 240. In one aspect, surgical tool 240 has an information storage unit 242, such as a solid state memory, RFID tag, bar code (including two-dimensional or matrix barcodes), etc., that identifies its tool or end effector information, such as one or more of identification of tool or end effector type, unique tool or end effector ID, number of tool disks used, location of those tool disks being used (e.g., from a total of six possible tool disks 244), type of transmission for the tool disks (e.g., direct drive, cable driven, etc.), what motion or actuation a tool disk imparts on the end effector, one or more tool calibration values (e.g., a rotational position of the tool disk as determined during factor testing / assembly of the tool), whether motion of the end effector is constrained by a maximum or minimum movement, as well as other tool attributes. In one aspect, the information storage unit 242 identifies minimal information, such as a tool ID, which control unit 210 may use to perform a lookup of the various tool attributes.

[0037] The tool drive 230 may include a communication interface 232 (e.g., a memory writer, a near field communications, NFC, transceiver, RFID scanner, barcode reader, etc.) to read the information from the information storage unit 242 and pass the information to control unit 210. Furthermore, in some aspects, there may be more than one information storage unit in surgical tool 240, such as one information storage unit associated with each tool disk 244. In this aspect, tool drive 230 may also include a corresponding sensor for each possible information storage unit that would be present in a given tool.

[0038] After surgical tool 240 is attached with tool drive 230, such that tool disks are brought into alignment and are superimposed on corresponding drive disks (although not necessarily mechanically engaged), and after the tool disk information is obtained or read by the control unit 210, the control unit 210 continues with an engagement detection and reporting process. This process detects when one or more of the tool disks (that are expected to be attached to a respective one or more of the drive disks) are mechanically engaged with their respective drive disks. That isbecause ataching the surgical tool 240 to the tool drive 230 does not necessarily ensure the proper mating or interlocking needed for engagement of a tool disk with a corresponding drive disk (e.g., due to misalignment of the mating features).

[0039] The engagement detection process may include actuating each of the one or more drive disks through its respective rotary motor so that a speed or velocity of the drive increases to a non-zero value. Thus, one or more motors of an actuator (e.g., the second actuator 238-j that drives a corresponding second drive disk 234-j) is activated so that the second drive disk 234-j is turning at a non-zero speed or velocity value. Then, based on a monitored, motor operating speed of the second actuator 238-j, while the later is driving the second drive disk 234-j, the mechanical engagement of the second tool disk 244-j with the second drive disk 234-j can be detected, as discussed in greater detail below. This process may be repeated for every drive disk 234 (of the tool drive 230) that is expected to be currently atached to a respective tool disk 244 (e.g., as determined based on the tool disk information obtained for the particular surgical tool 240 that is currently atached.)

[0040] Upon detecting that a particular type of surgical tool 240 has been atached with the tool drive 230, the control unit 210 activates one or more actuators (e.g., rotary motors) of the tool drive 230 that have been previously associated with that type of surgical tool 240. In some aspects, all actuators associated with corresponding drive disks 234 may be activated simultaneously while the detection of engagement may occur at random times for the various drive disks; alternatively, some of the drive disks may be actuated and their mechanical engagement detected sequentially (serially) one drive disk at a time, while others are actuated simultaneously; or any suitable combination of simultaneous and serial activations. If the processor fails to detect engagement of one of the actuated drive disks after a given time limit or rotation limit has been reached, then the control unit generates a notification of tool engagement failure.

[0041] FIG. 3 illustrates an example of the surgical tool 240 that has four tool disks, such as the second tool disk 244-j, arranged in a coplanar fashion on a mating surface of its housing. Each tool disk contributes to at least a portion of the movement or activation of end effector 246. Upon detecting the atachment of surgical tool 240 with tool drive 230 (e.g., joining of mating surfaces of the respectivehousings), control unit 210 (or its processor 312 while executing instructions stored in memory 314 as engagement control 316) performs a process which determines that, for this particular instance of the surgical tool 240, only the corresponding four drive disks, including the second drive disk 234-j, need to be actuated (by activating a corresponding second actuator 238-j - see FIG. 2) to perform the engagement process.

[0042] Returning to FIG. 2, after the detected attachment of surgical tool 240 with tool drive 230, one or more sensors 236, such as sensor 236-j, will measure one or more motor operating parameters of the second actuator 238-j as its motor is signaled to start to move. For example, the control unit 210 may process or interpret an output of a sensor that is sensing a position or velocity or speed of the respective motor in the second actuator 238-j, or the output of a sensor that is sensing a position or velocity or speed of the second drive disk 234-j that is coupled to the actuator 238- j . In one aspect, the actuator 238-j will turn in a direction that causes its attached (though not yet engaged) second tool disk 244-j to wind a cable in the transmission housing of the surgical tool 240, for cable driven surgical tools. As an example, see FIG. 4A in which motion 445 of the tool disk 244 takes up slack in or winds a cable 446. This turning of the tool disk 244 continues until engagement is detected or achieved as explained further below in connection with FIG. 4B and FIG. 4C.

[0043] Returning to FIG. 3, in some aspects, the motor operating parameters monitored by the control unit 210 (via sensors 236) are interpreted to mean successful mechanical engagement of a tool disk with a drive disk. These can include measurements of torque applied by the actuator 238-j as measured by a torque or force sensor, measurements of current supplied to a motor of the actuator 238-j when attempting to drive the actuator to move at a certain velocity (e.g., where the sensor 236-j may include a current sensing resistor in series with a motor input drive terminal), measurements of electrical impedance as seen into the input drive terminals of the motor of the actuator when attempting to drive the motor to move at a certain velocity (e.g., where the sensor 236-j may also include a voltage sensing circuit to measure voltage of the motor input drive terminal), speed of the actuator 238-j (e.g., where the sensor 236-j may include a position encoder on an output shaft of the actuator 238-j or on a drive shaft of the motor), as well as other parameters referred to here as motor operating parameters. While monitoring the one or more motoroperating parameters of a particular actuator, when one or more of these parameters satisfies (e.g., meets or reaches) a predetermined, condition or threshold, the detection of such a situation can be interpreted by control unit 210 as a mechanical engagement event. Note that satisfying the predetermined condition may for example mean that the monitored operating parameter exhibits certain changes, as per the threshold, relative to an operating parameter of another motor that is part of the same actuator 238-j or that is part of another actuator 238-i which is being controlled by the control unit 210 simultaneously during the engagement detection process.

[0044] In some aspects, detecting the motor operating speed of the actuator 238-j dropping to or below a motor speed threshold is the sole factor used by control unit 210 to determine that mechanical engagement of the second tool disk 244-j to the second drive disk 234-j has occurred. The following are some examples of such a process.

[0045] In another aspect, the selected actuator is signaled to turn so as to cause its attached tool disk 244 to rotate so that the end effector 246 that is connected to the tool disk 244 moves towards a physical constraint (e.g. a jaw opens until it stops against a cannula wall, a maximum in a range of motion is achieved when bumping against a hard stop in a fully open position, etc.) In yet another aspect, such as an endoscope where two actuators are sharing a load being the rotation of an endoscope camera and where there may be no hard stops against rotation of the camera, the selected actuator is signaled to rotate its attached first tool disk 244-i in a direction that opposes the motion of another, second tool disk 244-j that is also rotatably coupled to the same output shaft in the transmission housing of the surgical tool 240. In that instance, as soon as one of these tool disks engages, it will act as a physical constraint to the other tool disk. Other predetermined directions of movement may also be used consistent with the discussion herein.

[0046] Furthermore, in some aspects, the actuator’s movement is ramped or increased gradually by the control unit 210 (e.g., the control unit 210 signals or commands the actuator to start to rotate at a slow speed at the beginning of movement and then progressively increase the speed, and then progressively decrease the speed at detection of engagement).

[0047] In one aspect, the calibration values stored in the information storage unit 242 of the surgical tool may be used to expedite tool engagement. For example, the calibration values can include a factory determined position (angle) of a particular tool disk such as the second tool disk 244-j, recorded during product assembly or testing. The engagement process may need to have knowledge of a home position of a corresponding drive disk, in this case the second drive disk 234-j. This knowledge may be obtained by the control unit 210 performing a tool driver calibration routine, in which it determines when a particular drive disk 234 has reached a home position (as the control unit actuates the drive disk 234), such that position of that drive disk 234 is now known by the control unit 210. Note that the control unit 210 may do so while only relying on output from a position sensor that is in the tool drive 230, and the surgical tool 240 itself may be passive in that it has no electronic sensors in it.

[0048] Next, the control unit 210 may activate the corresponding actuator of the drive disk 234 so that the drive disk 234 turns at a high speed until a position variable of the drive disk 234 comes close to the factory determined position. When the drive disk satisfies a threshold distance relative to the factory-determined position (e.g., a home position of the tool disk) which implies that mating features of the tool disk and drive disk are near alignment, the speed may be reduced so as to increase the likelihood that the mating features will engage one another upon their initial encounter. This process may work for both direct transmissions as well as for tool disks that utilize a cable to drive the effector (as in FIG. 4A.) For the latter, the calibration value may include a rotation count (e.g., a number of complete rotations of a motor drive shaft) that can be used to limit the continued turning of the drive disk 234 once engagement has been detected, to ensure that a maximum length of winding of the cable is not exceeded, or an angle of rotation of the engaged pair, a tool disk 244 and its corresponding drive disk 234, is not exceeded.

[0049] FIG. 4A depicts an example of the tool disk 244 as one that uses a cable 446 to control movement of its end effector 246 (see FIG. 2.) The corresponding actuator 238-j (see FIG. 2) that is driving the drive disk 234 will move in the direction that winds the cable, here, the direction of motion 445. The direction of motion 445 will wind the cable 446 around the tool disk, where in this initial condition the cable 446 has some slack as shown that will disappear as the cable 446is being wound in the direction of motion 445. The control unit 210 may have knowledge of this direction of motion 445, based on having previously identified the type of surgical tool 240.

[0050] The tool disk 244 also has a pair of coupling features 447a, 447b on its disk face, which are depicted as hollow circles. Each coupling feature 447a, 447b may be a separate, cylindrical cavity formed in the disk face. Referring now to FIG. 4B, a drive disk 234 is concentrically aligned with the tool disk 244 once the tool is attached to the tool drive. That is, FIG. 4B illustrates drive disk 234 aligned and superimposed over the tool disk 244 such that their respective disk faces are brought into contact with one another. The drive disk 234 has a pair of coupling features 448a, 448b on its disk face, depicted as solid circles. Each coupling feature 448a, 448b may be a separate, cylindrical pin formed on the disk face. In this particular example, each of the coupling features 448 is sized to easily fit into either of the features 447 (once the two complementary features are aligned.) In FIG. 4B, the coupling features 447a, 447b are misaligned relative to the coupling features 448a, 448b even though the faces of their respective tool and drive disks may be in contact with one another. In other words, in FIG. 4B one or more mating or complementary pairs of features, such as the coupling features 447a-448a, or the coupling features 447b-448b, are not yet mechanically engaged with each other. During such a condition, the drive disk 234 continues to be driven by its actuator 238, to move (turn) in the direction of motion 445 past the tool disk 244, until mechanical engagement is reached in the condition depicted in FIG. 4C.

[0051] As illustrated in FIG. 4C, the drive disk 234 while turning has reached the point where both the coupling features 447a-448a have mechanically engaged with each other, and the coupling features 447b-448b have also mechanically engaged each other as shown, so that they all now move as one (as the drive disk 234 continues to turn.) In the example here, each pin-cavity pair is now interlocked as shown in this figure. In addition, at this point the cable 446 is now taught after having been winded and may thus serve to help hold the tool disk 244 in place (prevents its rotation) as drive disk 234 continues to turn in the direction of motion 445. Further turning of the drive disk 234 in the condition of FIG. 4C may increase tension in the cable 446, when the cable 446 pulls on its end effector 246 (see FIG. 2) until a physicalconstraint against further movement in the direction of motion 445 of the now- engaged drive disk 234 is reached. The control unit uses this physical constraint as described here, for detecting engagement of the drive disk with its corresponding tool disk. Examples of the physical constraint include a mechanical limit of a range of motion imposed by a joint of the end effector 246 (e.g., a joint that can only rotate about an axis from -45 to 45 degrees), and a physical barrier to movement such as a hard stop in the surgical tool 240 or a physical barrier outside of the surgical tool 240 such as a cannula wall that impedes further movement of the end effector 246.

[0052] The physical constraint on further turning of the drive disk 234 enables detection of the mechanical engagement by the control unit 210. The control unit 210 takes measurements of motor operating parameters and compares them to one or more thresholds that may have been predetermined to be indicative of engagement. In particular, the velocity or speed of the motor dropping below one or more threshold values indicates engagement, because at that point the motor is constrained from further movement (in the winding direction shown in FIGs 4A-4C), due to the engagement between the drive disk and the corresponding tool disk and due to the tool disk having reached a tool-side physical constraint. More particularly, when the control unit 210 detects the speed of the drive disk 234 (or the speed of its actuator motor) has dropped to (e.g., below) a velocity or speed threshold, the control unit 210 concludes that engagement has occurred between that drive disk and its corresponding tool disk 244. Note that the processor reaches this conclusion not in response to detecting a torque of the drive disk (or that of its operating motor), but solely in response to detecting the velocity or speed dropping to a threshold.

[0053] In some aspects, the physical constraint on the tool disk may be created by coordinating movement of multiple drive disks. For example, consider the case where two or more tool disks (in the same housing of the surgical tool 240) are connected by a transmission in the housing of the surgical tool 240 to share a load (the end effector 246), such as when a cutting or clamping tool may need to apply force beyond that which a single actuator 238 -j could supply. In one such aspect, two or more actuators are activated to turn in the same direction, and as a result their respective drive disks are turning in the same direction., and the two drive disks are driving the same output shaft inside the surgical tool 240 in the same degree offreedom (and so they are sharing the load presented by the end effector), due to the particular configuration of the transmission in the surgical tool 240. Now, if these two actuators are instead signaled to move in opposing directions, then as soon as a first one of the drive disks happens to engage its corresponding first tool disk, then 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), this creates a constraint for the other actuators (by signaling the first engaged actuator to either continue turning as it was or enter a position hold state.) The control unit 210 then detects engagement of the second actuator 238-j.

[0054] In the above scenario where the surgical tool has a transmission that connects two or more of its tool disks to share the same load (in the same degree of freedom), and if the surgical tool has a hard stop, and the control unit 210 expects or knows that this particular surgical tool 240 has a hard stop, then the control unit 210 signals the actuator of an engaged drive disk to continue to drive or turn in the same direction until the hard stop is detected by the control unit 210. The control unit 210 detects that the velocity or speed the engaged drive disk has dropped below the threshold. The other actuator may continue to be commanded to turn in the opposing direction, until the control unit 210 detects engagement of the other actuator (while the already engaged actuator holds its position at the hard stop.)

[0055] Returning to FIG. 2, and as discussed above, the tool identification performed by control unit 210 enables the latter to obtain knowledge of certain characteristics of the end effector 246. For example, the control unit 210 may use that identification process to determine whether two (or more) tool disks in the surgical tool 240 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, what actuators will be used by the surgical tool 240, and factory defined calibration values such as a home position of a tool disk. Note that a calibration value may encompass a range, e.g., 290 degrees + / - 4 degrees. Based on such a calibration value, e.g., a homeposition of the second tool disk 244-j and based on the present position of the corresponding second drive disk 234-j (determined using a position encoder in the tool drive 230), the control unit 210 can track the difference during the engagement process (as the actuator is signaled to turn.) So long as the difference is greater than a predetermined threshold, then the actuator is signaled to turn rapidly (fast rotation), and then in response to the difference becoming smaller than the threshold (implying that the drive disk is nearing the calibration value home position) the actuator is signaled to turn slowly (slow rotation). And that is expected to increase the chances of a reliable engagement being detected.

[0056] In some aspects, after an engagement is detected by control unit 210, the control unit 210 may take one or more additional actions with respect to the end effector 246 to confirm the engagement. For example, control unit 210 may subject the end effector to a predetermined set of one or more motions to test the engagement, such as signaling a drive disk to reverse direction thereby moving end effector in an opposite direction to what it was doing during the engagement process, moving the end effector to achieve an expected maximum degree of movement, etc. Such movements enable control unit 210 to for example reach a hard stop or reach a physical constraint again, which is detected as discussed herein based on one or more motor operating parameters, to confirm mechanical engagement between the tool disks and drive disks.

[0057] Furthermore, in some aspects, control unit 210 may utilize the hard stop or physical constraint to set a reference position of the end effector. For example, knowing that a hard stop is to occur when the end effector reaches 270° of rotation in a certain direction, control unit 210 can set calibration values for a position of the corresponding actuator or drive disk. Then, movement of the actuator or drive disk can be tracked based on number of rotations of the drive disk, motor shaft, gear ratio, drive disk / motor indexing, etc.

[0058] Furthermore, in some aspects, control unit 210 may signal actuation by one or more motors for a specified number of times, a specified number of rotations, or a combination thereof, when attempting to achieve engagement of tool disks with drive disks. When engagement is not achieved within a threshold amount of time, number of rotations, etc. control unit 210 may issue a warning to an operator of thesurgical robotic system (e.g., an operator of system 100 of FIG. 1) to detach and then reattach surgical tool 240 to restart the engagement process.

[0059] FIG. 3 is a block diagram showing an example of the surgical tool 240, tool drive 230, and control unit 210. The surgical tool 240 may be attached with the tool drive 230 by bringing complementary or mating surfaces of their respective housings in contact within one another. The attachment may also include fastening the housings with one another. Furthermore, one or more sensors (not shown) of the tool drive 230 may be used by the control unit 210 to detect the attachment, by reading data from the surgical tool 240 that identifies the surgical tool 240. This data may indicate one or more of the following: which tool disks are to be operated so as to control movements of the end effector 246; a calibration value such as the position or angle of a tool disk at a hard stop; which tool disks contribute to movement of or are connected by a transmission to other tool disks in the surgical tool 240 (for example to share their load.) The data may be transferred to the control unit 210 via a communication link (e.g., a wired or wireless link) established between a communications interface 318 of the control unit 210 and sensor readout circuitry (not shown) in the tool drive 230. The data may then be stored in memory 314 as part of an engagement control program (engagement control 316) and may be associated with that particular surgical tool 240 so long as the latter remains attached to the tool drive 230.

[0060] The control unit 210 including its programmed processor 312 may be integrated into the surgical robotic system 100 (FIG. 1) for example as a shared microprocessor and program memory within the control tower 103. Alternatively, the control unit 210 may be implemented in a remote computer such as in a different room than the operating room, or in a different building than the operating arena shown in Fig. 1. Furthermore, control unit 210 may also include, although not illustrated, user interface hardware (e.g., keyboard, touch-screen, microphones, speakers) that may enable manual control of the robotic arm and its attached surgical tool 240, a power device (e.g., a battery), as well as other components typically associated with electronic devices for controlling surgical robotic systems.

[0061] Memory 314 is coupled to one or more processors 312 (generically referred to here as “a processor” for simplicity) to store instructions for execution bythe processors 312. In some aspects, the memory is non-transitory, and may store one or more program modules, including a tool control 320 and an engagement control 316, whose instructions configure the processor 312 to perform the engagement processes described herein. In other words, the processor 312 may operate under the control of a program, routine, or the execution of instructions stored in the memory 314 as part of the tool control 320 and engagement control 316 to execute methods or processes in accordance with the aspects and features described herein.

[0062] In response to detecting the attachment of the surgical tool 240 with the tool drive 230, engagement control 316 performs (or rather configures the processor 312 to perform) a process for detecting the mechanical engagement of tool disks with corresponding drive disks (which are actuator driven), beginning with detecting engagement of a first tool disk 244-i with a corresponding first drive disk 234-i. The engagement control 316 may signal (through the tool control 320) that one or more of the actuators of tool drive 230 impart motion of their respective drive disks. In some aspects, these instructions or signals include instructions to energize, activate or otherwise provide power to a motor in the tool drive 230 so that the motor can produce or apply a specific amount of torque, cause the drive disk to rotate at a specific speed and direction, by applying a certain voltage command, current command, etc. Furthermore, the motion of each drive disk can be controlled to start rapidly initially during the engagement detection process, and then ramp down slowly once engagement is detected, or proximity to alignment of mating features is detected or a predetermined time limit is reached without detecting engagement. For instance, based on the relative position of a drive disk to a corresponding tool disk (which may be based on a known calibration value), the actuator speed is ramped down to a predetermined speed, e.g., until the drive disk is within a threshold distance of where the mating features become aligned.

[0063] The engagement control 316 monitors a motor operating parameter of a motor of the actuator of the tool drive 230. As discussed herein, the motor operating parameter includes voltage supplied to a motor or motor speed. The monitored parameter is also being compared to a threshold, so that when the threshold is reached then a mechanical engagement event condition is deemed to have occurred (between, for example, the first tool disk 244-i and the first drive disk 234-i.) As discussedherein, mechanical engagement is expected to be detected when corresponding mating features of the tool disk and the drive disk align and fasten with one another so that rotation of the drive disk will cause for example both immediate and proportional rotation of the mechanically engaged tool disk (as one with the drive disk.) Such engagement is expected to be detected when, for instance, the motor speed drops to or below a threshold indicative of a hard stop being reached. The engagement control 316 thus infers or deduces that the tool disk 244 and its corresponding drive disk 234 have mechanically engaged with one another (e.g., fastening of respective disk mating features with one another).

[0064] Engagement control 316, based on having detected engagement of tool disks to drive disks, or based on a countdown timer having expired without detecting engagement, generates a notification for an operator of the surgical robotic system. The notification may either indicate that engagement has occurred so that the surgical tool 240 is ready for use in a teleoperation mode of the system, or that engagement has not occurred and so the surgical tool 240 should be reattached.

[0065] FIG. 5A is a flow diagram illustrating a process 500 for detecting engagement of a tool disk in a surgical tool with a corresponding tool disk in a tool drive, of a surgical robotic system, in accordance with an aspect of the disclosure. The process 500 may be performed by a programmed processor (also referred to here as processing logic), configured according to software stored in memory (e.g., the processor 312 and the memory 314 of FIG. 3, where the processor 312 is configured according to the instructions of the tool control 320 and the engagement control 316.)

[0066] Referring to FIG. 5A, processing logic begins by activating an actuator of the tool drive to rotate a coupled drive disk of the tool drive (processing block 502). For example, processing logic may activate a linear or rotary actuator of the tool drive (e.g., tool drive 230) to turn or rotate a drive disk (e.g., the first drive disk 234-i). Furthermore, as discussed herein, when mechanically engaged, the rotation of the first drive disk 234-i will cause immediate or direct rotation of the corresponding first tool disk 244-i of a surgical tool (e.g., surgical tool 240).

[0067] Processing logic monitors velocity or speed of the actuator that is causing the rotation of the drive disk while activating the motor of that actuator (processing block 504.) The processing logic is also continuously comparing themonitored speed to a threshold, and when the monitored speed has dropped to the threshold, the processing logic at that point detects that the drive disk becomes mechanically engaged with the tool disk (processing block 506). This reduction in speed may be due to the drive disk reaching a physical constraint against further rotation of the tool disk (e.g., reaching a mechanical limit of a range of motion when a physical barrier to the movement is encountered, a maximum degree of movement of the end effector of the tool is reached, opposition with another activated motor actuator occurs, etc.) When mechanical engagement of the drive disk with the tool disk is detected, one or more additional actions, such as generating system or operator notifications, initiating one or more engagement verification operations, storing reference values, etc. may be performed by the processing logic.

[0068] FIG. 5B is a flow chart illustrating a process 550 for detecting engagement of a tool disk with a drive disk based on motor speed of an actuator that is driving the drive disk. The process 550 is performed by processing logic that may comprise any combination of hardwired circuitry and programmed processor, where for example the process 550 may be performed by the processor 312 programmed in accordance with the tool control 320 and engagement control 316 described above. The process may begin by detecting that a detachable surgical tool has been attached to a tool drive of a robotic arm of a surgical robotic system (processing block 552). The attachment may be detected by interpreting the output signals of sensors in the tool drive, indicating the tool drive has come within wireless detection range of a detachable surgical tool, or indicating the tool drive is conductively connected with an information storage unit in the detachable surgical tool. As discussed herein, the information storage unit may store data such as a tool identifier. It may also include additional data or tool attributes such as which of several available tool disks in the tool housing are actually connected by a transmission in the housing to the end effector in the detachable surgical tool, what type of transmission in the tool controls movement of the end effector (e.g., cable driven, direct drive, etc.), what direction of movement or rotation is allowed, if there are any ranges of such movement or rotation, calibration values (e.g., cable lengths, current cable length, maximum winding, rotational position of tool disks or a home position of a tool disk, etc.), as well as other tool attributes discussed herein.

[0069] In processing block 554, at least one motor of the tool drive is then activated causing the at least one motor to rotate a coupled drive disk in the tool drive. The drive disk is associated with a corresponding a tool disk which in turn is connected by a transmission in the surgical tool to control motion of the end effector. In one aspect, activation means that a current is supplied by the tool control 320 to the motor to for example achieve a certain torque or achieve a direction of movement, so that the motor will cause the drive disk to start to rotate to reach a predetermined speed in a predetermined direction. In other words, processing logic causes a signal to be sent to a motor driver circuit, commanding the motor driver circuit to apply power to or energize the motor. In some aspects, the predetermined speed is set based on a determination, at the time of the detected attachment of the tool drive with the detachable surgical tool, of for example, the type of tool, tool drive transmission type (e.g., cable driven, direct drive, etc.), type of restraint that will be encountered (e.g., a hard stop, a physical constraint, opposing motion constraint), or a combination of such factors. The motor speed of the at least one motor of the tool drive is then monitored (processing block 556).

[0070] The processing logic repeatedly checks to see whether or not an engagement condition has been met, e.g., a monitored motor operating parameter has reached a threshold (processing block 558.) If so, then a mechanical engagement event is flagged, signifying that the processing logic has detected that the drive disk has mechanically engaged with its corresponding tool disk (processing block 564). As discussed herein, this threshold is indicative of the mechanical engagement of the drive disk. In some instances, the end effector may be subject to a physical constraint, such as a maximum range of motion of a joint, a hard stop (e.g., as imposed by a cannula wall), an opposing motion of another drive disk, as well as other physical constraints. In those cases, the initial speed and direction of movement of the motor are selected to advance the end effector or tool disk towards the physical constraint. Then, when the physical constraint is reached, the monitored speed will drop to zero. The threshold may refer to a velocity or speed that is lower than a nominal speed of the motor during its initial activation, i.e., when the drive disk is visibly turning, for example at a noise floor signifying zero speed of the respective rotary motor or of thedrive disk, which is when the respective rotary motor or the drive disk has visibly stopped moving.

[0071] In response to the detected engagement of the drive disk with the corresponding tool disk, the processing logic deactivates the actuator which stops turning the drive disk (processing block 566). At that point, when the motion of the drive disk is stopped, one or more reference values associated with the position or state of the end effector at that point may be stored for later reference and use. For example, where a physical constraint was used to detect the engagement, an index value of the motor, a rotation count, a position encoder value, etc. at that moment can be stored, and used later for re-locating the end effector at or near the physical constraint. The physical constraint may be, e.g., maximum cable length, cannula wall, maximum of a range of motion, etc. To prevent excessive tension in a cable in the case of a cable driven tool, the motor is deactivated immediately or simultaneously or nearly simultaneously in response to the detection performed at block 558.

[0072] After processing block 566 has been performed for a given drive disktool disk pair, the processing logic proceeds in processing block 565 to repeat the processing blocks 554-566, beginning with processing block 554, for each additional drive disk in the attached surgical tool. That way, a variable number of drive disks are actuated and evaluated for detecting engagement, and so if any one of the drive disks fails to engage with its respective tool disk, then the processing block 562 generates a notification of failed tool engagement.

[0073] Once engagement of all of the relevant drive disks (those that correspond to in-use tool disks of the particular surgical tool) has been detected in processing block 567 (where the process described above in blocks 554-556-558-564- 566 has been performed for each respective drive disk) then a notification of tool engagement is then generated (processing block 568). The notification may be a visual notification (e.g., a graphical user interface notification), an audible notification (e.g., a tone, sound, etc.), sensory (e.g., a haptic notification), or a combination of such generated by user interface hardware of the surgical robotic system.

[0074] Returning briefly to processing block 558, when the engagement condition is not met (e.g., a monitored motor operating parameter does not satisfy athreshold such that mechanical engagement of a tool disk and a corresponding drive disk has not occurred), a determination of whether a time or rotation limit has been reached is performed (processing block 560). A failure to engage may be due to a broken cable, a tool disk and drive disk not positioned close enough to each other to allow for engagement, etc. The time limit may be a predetermined maximum time interval (countdown timer value) in which a drive disk is allowed to rotate without detecting mechanical engagement with a tool disk. Similarly, the rotation limit may be a number of motor rotations necessary to impart one or more full rotations of its respective drive disk. For example, if the rotation limit is associated with one full rotation of the drive disk, it is assumed that engagement should occur within a single revolution of a drive disk. If the time limit, rotation limit, or some combination of limits are not reached (processing block 560), the monitoring of the one or more motor operating parameter values continues (return to processing block 556.) However, if the time limit or rotation is reached (processing block 560), then a notification, similar to the notification of processing block 568, that an error has occurred and / or tool engagement has failed is generated (processing block 562). In this case, an operator of the surgical system may be instructed to detach the surgical tool from the tool drive, and then re-attach them to restart the engagement process of FIG. 5B.

[0075] Turning now to FIG. 5C, this is a diagram of a process performed by a control unit for engaging a surgical robotic tool with a tool drive, as part of a surgical robotic system. The system includes the surgical tool 240 that is depicted in Fig. 2, having one or more tool disks at a proximal end and an end effector at a distal end thereof as shown. A tool drive (e.g., tool drive 230) is mounted at a distal end of a surgical robotic arm 220 as shown, where the tool drive 230 has one or more drive disks 234 each driven by a rotary motor within a housing of the tool drive. Each drive disk 234 is to be attached to a tool disk 244 of the surgical tool 240 to impart motion to the end effector 246.

[0076] Staying with FIG. 5C, the process for engaging a tool disk with a drive disk is performed by a control unit, and in particular by one or more processors of the control unit that are configured to (or programmed to) do so. Operation may begin with detecting that the surgical tool is attached to the tool drive (block 582); this maybe done by the processor wirelessly or via a wired connection reading an identification or other attributes of the tool, which has been brought into contact with the tool drive such that a tool disk comes into contact with a corresponding or respective drive disk. The control unit may then actuate a drive disk through its rotary motor (block 584), and detect, during the actuation, that the drive disk is engaged to its respective tool disk (block 586); the drive disk is said to be engaged to the tool disk when a pair of coupling features of the drive disk and the tool disk (there may be more than one pair, e.g., two as shown in FIG. 4A-FIG. 4C, or more) become interlocked. To detect the engagement, the control unit needs only rely on recognizing when a sensed speed of the rotary motor drops to or below a predetermined velocity or speed threshold.

[0077] The threshold may be a velocity at which the motor is substantially stopped; for example, the threshold may be just above a noise floor of a sensed velocity or speed variable and signifies zero speed of the respective rotary motor or of the drive disk, which is when the respective rotary motor and the drive disk have visibly stopped moving. This drop in velocity may be caused by at least one of: the end effector reaching a joint limit, an external force on the end effector, a motion constraint due to another motor of the tool drive being activated, and a combination thereof.

[0078] There may be more than one tool disk that is in use for operating the end effector. In that case, the engagement process described above is repeated or performed for an additional tool disk (which has a corresponding drive disk in the tool drive) - as block 589. The process then continues with block 587 where the control unit checks if all relevant tool disks have been detected as engaged to their respective drive disks, in which case it signals (block 588) for example a user interface subsystem of the surgical robotic system to report engagement of the surgical tool, only if all of the tool disks that are expected to be in use for the particular surgery have been detected as engaged with their respective drive disks.

[0079] In the process of Fig. 5C, if engagement of a drive disk is not detected (block 586) when a time limit or rotation limit for the actuation in block 584 is reached (block 583), then the processor stops actuating the drive disk (block 585) and generates a notification that tool engagement has failed (block 590.)

[0080] In one aspect, a feedback loop may be used to monitor the motor speed and detect when the velocity threshold has been reached. FIG. 6 depicts a block diagram of a feedback loop used to control the velocity of a motor of a tool drive using velocity feedback. The feedback loop may be implemented in hardware, firmware, software, or a combination thereof. A velocity command (which may include a direction and a speed) is received by a controller 602. Controller 602 may be, for example, a proportional-integral-derivative controller or any generic non-linear or linear proportional-integral-derivative, PID, controller that is part of a loop / feedback mechanism to provide an appropriate motor current (e.g., the controller output, ctrlr out) to drive motor / actuator 604 at the velocity and in the direction of the velocity command (also referred to as velocity setpoint.) For example, the direction may be in a winding direction of a cable driven second tool disk 244-j . As another example, the direction may be a direction that will oppose the motion of another motor whose attached first tool disk 244-i under normal operating conditions is cooperating with, not fighting against, the second tool disk 244-j to share a load. As yet another example, the direction may be a direction that causes the motor to advance the end effector towards a hard stop, such as a physical barrier or a mechanical limit of range of motion. In one aspect, the controller 602 may use various values, such as desired torque to achieve the velocity, current to achieve the velocity, impedance indicative of a velocity, etc. as a measure for generating the controller’s current output to motor / actuator 604.

[0081] A sensor, such as a velocity sensor, or a combination of sensors, measures the velocity or speed of the motor / actuator. The measured velocity is then provided as feedback back to controller 602 as shown in the figure, which may calculate an error based on a disparity between the measured velocity of the motor and the commanded velocity. The controller 602 responds to the disparity by adjusting its controller output, e.g., a motor current command to the motor / actuator 604, a torque to be achieved by the motor / actuator 604, an impedance value, etc. that will cause the motor / actuator 604 to move towards the velocity command or setpoint. In some aspects, controller 602 may output an estimate of the motor velocity, calculated as a result of executing the feedback loop, and this estimated motor velocity is then used for the engagement detection processes described here.

[0082] In another aspect, the controller 602 can include a saturation block (not shown) which ensures that the controller output CtrlrOut, as a value that is setting the motor current, does not exceed a saturation threshold, so that the actual motor current does not exceed a current threshold or actual motor torque does not exceed a torque threshold beyond which the surgical tool could be damaged. In addition, during the engagement detection process, the CtrlrOut value that sets the motor current should result in motor torque that is higher than instrument friction in the corresponding drive axis of the end effector in the surgical tool; this ensures that the corresponding tool disk is being driven at nominal speed during the engagement detection process without stalling. In another aspect, the saturation block is configured so that its saturation threshold is automatically reduced (to a factory selected value that may be specific to the attached surgical tool, for example), in response to, and for instance as soon as possible after detecting the speed of the drive disk or its respective motor has dropped to the speed threshold. This advantageously avoids the application of excessive force to the now mated features of the drive disk and the tool disk and the transmission in the surgical tool.

[0083] In another aspect, the feedback from the motor / actuator 604 may be used as a motor operating parameter value (motor speed) supplied to the processor for purposes of monitoring during the engagement detection process. Othe variables indicative of motor speed that might be computed in the controller 602 (e.g., adjusted, and non-adjusted) may be used for the monitored motor speed (by the engagement detection process.)

[0084] The above description of illustrated aspects of the disclosure, including what is described below in the Abstract, is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. While specific aspects of, and examples for, the disclosure are described herein for illustrative purposes, various modifications are possible within the scope of the disclosure, as those skilled in the relevant art will recognize. For example, although FIG. 4A-FIG. 4C depict a surgical tool 240 that has a cable-driven transmission connecting the tool disk 244 to the end effectors (not shown), the engagement process described above is also applicable to other types of surgical tools having different transmissions (not necessarily cable-driven.) These modifications can be made in light of the above detailed description. The terms usedin the following claims should not be construed to limit the disclosure to the specific aspects disclosed in the specification. Rather, the scope of the disclosure is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.

Claims

CLAIMSWhat is claimed is:

1. A surgical robotic system for reporting engagement of a surgical tool with a tool drive, the system comprising a control unit having one or more processors configured to: detect that a surgical tool is attached to a tool drive on a surgical robotic arm, wherein the surgical tool comprises one or more tool disks, a transmission, and an end effector, and the transmission couples the one or more tool disks to the end effector so that motion of the one or more tool disks is transferred to motion of the end effector, the tool drive comprises one or more drive disks each being coupled to be actuated by a respective motor, and the respective motor imparts motion to the end effector via the transmission when the respective motor actuates the drive disk and the drive disk is engaged with a respective one of the one or more tool disks; actuate each of the one or more drive disks through the respective motor so that a speed of the drive disk or the respective motor increases to a non-zero value; and during the actuation of each of the one or more drive disks, determine that the drive disk is engaged to the respective one of the one more tool disks in response to detecting the speed of the drive disk or the respective motor has dropped to a speed threshold and without detecting a torque of the respective motor.

2. The surgical robotic system of claim 1 wherein the one or more processors are configured to: report an engagement of the surgical tool with the tool drive, in response to having determined that all of the one or more drive disks are engaged to the one or more tool disks.

3. The system of claim 1 wherein each of the one or more drive disks is engaged to the respective one of the one more tool disks when a pair of coupling features of the drive disk is interlocked with a pair of coupling features of the respective one of the one or more tool disks.

4. The system of claim 1 wherein detecting the speed comprises processing an output of a sensor that is sensing a position or velocity or speed of the respective motor or of the drive disk.

5. The system of claim 4 wherein the speed threshold is above a noise floor but signifies zero speed of the respective motor or of the drive disk, which is when the respective motor and the drive disk have visibly stopped moving.

6. The system of claim 1 wherein the speed drops to the speed threshold due to i) the end effector reaching a hard stop or a tool limit, ii) an external force on the end effector, or iii) a motion constraint due to another motor of the tool drive being activated.

7. The system of claim 1 wherein the one or more drive disks are a plurality of drive disks, and the one or more processors actuate all of the plurality of drive disks, through their respective motors, sequentially and determine that all of the plurality of drive disks are engaged sequentially.

8. The system of claim 1 wherein the one or more drive disks are a plurality of drive disks, and the one or more processors actuate all of the plurality of drive disks, through their respective motors, in any order or all at once to determine that all of the plurality of drive disks are engaged.

9. The system of claim 1 wherein the one or more drive disks are a plurality of drive disks, and the one or more processors actuate all the plurality of drive disks, through their respective motors, simultaneously, when determining that one of the plurality ofdrive disks is engaged.

10. A method for reporting engagement of a surgical tool with a tool drive of a surgical robotic system, the method comprising: detecting that a surgical tool is attached to a tool drive on a surgical robotic arm, wherein the surgical tool comprises one or more tool disks, a transmission, and an end effector, and the transmission couples the one or more tool disks to the end effector to transfer motion of the one or more tool disks to motion of the end effector, and the tool drive comprises one or more drive disks each being coupled to be actuated by a respective motor; actuating each of the one or more drive disks through the respective motor which causes a speed of the drive disk or the respective to increase to a non-zero value; and during the actuation of each of the one or more drive disks, determine that the drive disk is engaged to the respective one of the one more tool disks in response to detecting the speed of the drive disk or the respective motor has dropped to a speed threshold without detecting a torque of the respective motor.

11. The method of claim 10 further comprising: reporting an engagement of the surgical tool with the tool drive, in response to having determined that all of the one or more drive disks are engaged to the one or more tool disks.

12. The method of claim 10 wherein each of the one or more drive disks is engaged to the respective one of the one more tool disks when a pair of coupling features of the drive disk is interlocked with a pair of coupling features of the respective one of the one or more tool disks.

13. The method of claim 10 wherein detecting the speed comprises processing an output of a sensor that is sensing a position or velocity or speed of the respective motor or of the drive disk.

14. The method of claim 13 wherein the speed threshold is above a noise floor but signifies zero speed of the respective motor or of the drive disk, which is when the respective motor and the drive disk have visibly stopped moving.

15. The method of claim 10 wherein the speed drops to the speed threshold due to i) the end effector reaching a hard stop or a tool limit, ii) an external force on the end effector, or iii) a motion constraint due to another motor of the tool drive being activated.

16. The method of claim 10 wherein the one or more drive disks are a plurality of drive disks, and all of the plurality of drive disks are actuated, through their respective motors, sequentially and all of the plurality of drive disks are determined to be engaged sequentially.

17. The method of claim 10 wherein the one or more drive disks are a plurality of drive disks, and all the plurality of drive disks are actuated, through their respective motors, simultaneously, when determining that one of the plurality of drive disks is engaged.

18. The method of claim 10 wherein the one or more drive disks are a plurality of drive disks, and all of the plurality of drive disks are actuated, through their respective motors, in any order to determine that all of the plurality of drive disks are engaged.

Images