US-20260124011-A1 - SYSTEMS AND METHODS FOR CONTROL OF A SURGICAL SYSTEM

US20260124011A1US 20260124011 A1US20260124011 A1US 20260124011A1US-20260124011-A1

Abstract

Systems and methods are provided for control of a surgical system. Accordingly, a first output signal is received from a force sensor unit in response to a first commanded movement of a distal end portion of a medical instrument within a cannula. A force sensor bias value is determined based on a difference between a portion of the first output signal and a baseline output signal for the force sensor. The validity of the force sensor bias value is determined based on a deviation magnitude between the second output signal, which is modified by the force sensor bias value, and the baseline output signal. On a condition that the force sensor bias value is valid, haptic feedback is provided to the user control unit based on a load indication from the force sensor unit as modified by the force sensor bias value.

Inventors

Clifford N. BARGAR
J. Scot Hart
Ashwinram Suresh
Lawton N. Verner

Assignees

Intuitive Surgical Operations, Inc.

Dates

Publication Date: 20260507
Application Date: 20231011

Claims (20)

1 - 54 . (canceled)
55 . A method of control for a surgical system, the surgical system including a manipulator unit, a controller, a user control unit, and a medical instrument supported by the manipulator unit and operably coupled to be controlled by the user control unit via the controller, the medical instrument including a force sensor unit, the method comprising: receiving, via the controller, a first output signal from the force sensor unit in response to a first commanded movement of a distal end portion of the medical instrument within a cannula; determining, via the controller, a force sensor bias value based on a difference between a portion of the first output signal and a baseline output signal for the force sensor unit; receiving, via the controller, a second output signal from the force sensor unit in response to a second commanded movement, the second output signal being modified by the force sensor bias value; determining, via the controller, whether the force sensor bias value is valid based on a deviation magnitude between the second output signal and the baseline output signal, the force sensor bias value being valid on a condition that the deviation magnitude is within a predefined tolerance range; and on a condition that the force sensor bias value is valid, providing, via a haptic feedback module of the controller, a haptic feedback to the user control unit based on a load indication from the force sensor unit as modified by the force sensor bias value.
56 . The method of claim 55 , wherein: the first commanded movement includes a roll motion of the distal end portion about a longitudinal shaft axis from a first roll limit, through a neutral roll orientation, to a second roll limit, and back to the neutral roll orientation; and the controller maintains the distal end portion of the medical instrument within the cannula throughout the roll motion.
57 . The method of claim 55 , wherein: the manipulator unit includes a plurality of motors and a plurality of drive discs; each individual drive disc of the plurality of drive discs is coupled to a corresponding individual motor of the plurality of motors; the medical instrument includes a plurality of instrument discs configured to receive motion from the plurality of drive discs to move the distal end portion; each individual instrument disc of the plurality of instrument discs is configured to engage a corresponding individual drive disc of the plurality of drive discs; and the method includes: detecting, via the controller, an installation of the medical instrument on the manipulator unit, initiating, via the controller, an engagement process for the medical instrument in response to detecting the installation, and rotating, via the controller, at least one of the plurality of drive discs via the plurality of motors until the drive disc engages the corresponding instrument disc and a stop condition is achieved for the drive disc.
58 . The method of claim 57 , wherein: the plurality of drive discs includes a roll-drive disc configured to generate a roll motion of the distal end portion of the medical instrument about a longitudinal shaft axis; and the method includes: maintaining the roll-drive disc at a first roll limit, rotating at least one non-roll-drive disc of the plurality of drive discs to a neutral position, and executing the first commanded movement by generating the roll motion of the distal end portion through a roll range of motion to a second roll limit.
59 . The method of claim 55 , wherein: the method includes: determining, via the controller, a difference between a magnitude of the force sensor bias value and a defined maximum force sensor bias value, and on a condition in which the magnitude of the force sensor bias value exceeds the maximum force sensor bias value, providing, via the controller, an error signal to an operator of the surgical system.
60 . The method of claim 55 , wherein: the first commanded movement includes establishing the distal end portion of the medical instrument in a first pose, transitioning the distal end portion away from the first pose, and returning the distal end portion to the first pose; and the method includes: determining, via the controller, a variability of the first output signal between each instance of the distal end portion in the first pose, and on a condition in which the variability exceeds a maximum variability value, providing, via the controller, an error signal to an operator of the surgical system.
61 . The method of claim 60 , wherein: the method includes: on a condition in which the variability exceeds the maximum variability value, repeating the first commanded movement of the distal end portion of the medical instrument within the cannula to generate a replacement first output signal, and determining, via the controller, the force sensor bias value based at least in part on the replacement first output signal.
62 . The method of claim 55 , wherein: the medical instrument includes a beam coordinate system having a first axis, a second axis, and a third axis that are orthogonal to one another; the force sensor bias value is a first force sensor bias value that is parallel to the first axis; and the method includes: resolving, via the controller, the first output signal in the beam coordinate system to determine a first axis component, a second axis component, and a third axis component of the first output signal, determining, via the controller, a second force sensor bias value parallel to the second axis based on a difference between a portion of the second axis component and a baseline second axis component, and determining, via the controller, a third force sensor bias value parallel to the third axis based on a difference between a portion of the third axis component and a baseline third axis component.
63 . The method of claim 55 , wherein: the portion of the first output signal is associated with the medical instrument being in a specified sampling pose.
64 . The method of claim 63 , wherein: the specified sampling pose includes a roll orientation of the distal end portion of the medical instrument that corresponds to a defined zero orientation.
65 . The method of claim 55 , wherein: determining the force sensor bias value includes identifying a free-space portion of the first output signal that corresponds to a free-space condition of the distal end portion of the medical instrument; and the force sensor bias value corresponds to the difference between an average magnitude of the free-space portion of the first output signal and the baseline output signal for the force sensor unit.
66 . The method of claim 65 , wherein: the method includes: determining, via the controller, a confidence score for the free-space portion, and implementing, via the controller, a command action based at least in part on the confidence score; and the confidence score is indicative of a correlation between the free-space portion and a condition of the medical instrument in which the first commanded movement of the medical instrument is not affected by contact with another object.
67 . The method of claim 66 , wherein: on a condition in which the confidence score is less than a confidence score threshold, implementing the command action includes: repeating the first commanded movement of the distal end portion of the medical instrument within the cannula to generate a replacement first output signal, identifying a replacement free-space portion of the first output signal, and determining the force sensor bias value based at least in part on the replacement free-space portion.
68 . The method of claim 55 , the method includes: on a condition in which the difference between the second output signal and the baseline output signal falls outside the tolerance range, providing, via the controller, an error signal to an operator of the surgical system; and implementing a command action based at least in part on the error signal, implementing the command action includes: repeating the first commanded movement of the distal end portion of the medical instrument within the cannula to generate a replacement first output signal, determining, via the controller, a replacement force sensor bias value based on a difference between a portion of the replacement first output signal and the baseline output signal for the force sensor unit, and providing, via the controller, the haptic feedback to the user control unit based on the load indication from the force sensor unit as modified by the replacement force sensor bias value.
69 . A surgical system, comprising: a medical instrument including a distal end portion, the medical instrument being supported by a manipulator unit; a force sensor unit coupled to the medical instrument; user control unit operably coupled to the medical instrument and the manipulator unit; and a controller operably coupled to the manipulator unit, the user control unit, and the force sensor unit, the controller comprising at least one processor and a haptic feedback module, controller being configured to perform a plurality of operations, the plurality of operations comprising: receiving a first output signal from the force sensor unit in response to a first commanded movement of the distal end portion of the medical instrument within a cannula, determining a force sensor bias value based on a difference between a portion of the first output signal and a baseline output signal for the force sensor unit, receiving a second output signal from the force sensor unit in response to a second commanded movement, the second output signal being modified by the force sensor bias value, determining whether the force sensor bias value is valid based on a deviation magnitude between the second output signal and the baseline output signal, the force sensor bias value being valid on a condition that the deviation magnitude is within a predefined tolerance range, and on a condition that the force sensor bias value is valid, providing, via the haptic feedback module, a haptic feedback to the user control unit based on a load indication from the force sensor unit as modified by the force sensor bias value.
70 . The system of claim 69 , wherein: the first commanded movement includes a roll motion of the distal end portion about a longitudinal shaft axis from a first roll limit, through a neutral roll orientation, to a second roll limit, and back to the neutral roll orientation; and the controller is configured to maintain the distal end portion of the medical instrument within the cannula throughout the roll motion.
71 . The system of claim 69 , wherein: the first commanded movement includes a linear movement of the distal end portion parallel to a longitudinal shaft axis; and the controller is configured to maintain the distal end portion of the medical instrument within the cannula throughout the linear movement.
72 . The system of claim 69 , wherein: the manipulator unit includes a plurality of motors and a plurality of drive discs; each individual drive disc of the plurality of drive discs is coupled to a corresponding individual motor of the plurality of motors; the medical instrument includes a plurality of instrument discs configured to receive motion from the plurality of drive discs to move the distal end portion; each individual instrument disc of the plurality of instrument discs is configured to engage a corresponding individual drive disc of the plurality of drive discs; and the plurality of operations includes: detecting an installation of the medical instrument on the manipulator unit, initiating an engagement process for the medical instrument in response to detecting the installation, and rotating at least one of the plurality of drive discs via the plurality of motors until the drive disc engages the corresponding instrument disc and a stop condition is achieved for the drive disc.
73 . The system of claim 72 , wherein: the plurality of drive discs includes a roll-drive disc configured to generate a roll motion of the distal end portion of the medical instrument about a longitudinal shaft axis; and the plurality of operations includes: maintaining the roll-drive disc at a first roll limit, rotating at least one non-roll-drive disc of the plurality of drive discs to a neutral position, and executing the first commanded movement by generating the roll motion of the distal end portion through a roll range of motion to a second roll limit.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the filing date benefit of U.S. Provisional Ser. No. 63/415,491 , entitled “Systems and Methods for Control of a Surgical System,” filed Oct. 12, 2022, the disclosure of which is incorporated herein by reference in its entirety. BACKGROUND The embodiments described herein relate to surgical systems, and more specifically to teleoperated surgical systems. More particularly, the embodiments described herein relate to systems and methods for determining a force sensor bias value to be applied to a force sensor output in order to control a surgical system that includes a force feedback that may be provided to a system operator. Known techniques for Minimally Invasive Surgery (MIS) employ instruments to manipulate tissue that can be either manually controlled or controlled via hand-held or mechanically grounded teleoperated medical systems that operate with at least partial computer-assistance (“telesurgical systems”). Many known MIS instruments include a therapeutic or diagnostic end effector (e.g., forceps, a cutting tool, or a cauterizing tool) mounted on an optional wrist mechanism at the distal end of a shaft. During an MIS procedure, the end effector, wrist mechanism, and the distal end of the shaft are typically inserted into a small incision or a natural orifice of a patient via a cannula to position the end effector at a work site within the patient's body. The optional wrist mechanism can be used to change the end effector's position and orientation with reference to the shaft to perform a desired procedure at the work site. In known instruments, motion of the instrument as a whole provides mechanical degrees of freedom (DOFs) for movement of the end effector and the wrist mechanisms generally provide the desired DOFs for movement of the end effector with reference to the shaft of the instrument. For example, for forceps or other grasping tools, known wrist mechanisms are able to change the pitch and yaw of the end effector with reference to the shaft. A wrist may optionally provide a roll DOF for the end effector, or the roll DOF may be implemented by rolling the shaft. An end effector may optionally have additional mechanical DOFs, such as grip or knife blade motion. In some instances, wrist and end effector mechanical DOFs may be combined. For example, U.S. Pat. No. 5,792,135 (filed May 16, 1997) discloses a mechanism in which wrist and end effector grip DOFs are combined. Force sensing surgical instruments are known and together with associated telesurgical systems may deliver haptic feedback during a MIS procedure to a surgeon performing the procedure. The haptic feedback may increase the immersion, realism, and intuitiveness of the procedure. For effective haptics rendering and accuracy, force sensors may be placed on a medical instrument and as close to the anatomical tissue interaction as possible. One approach is to include a force sensor unit having electrical sensor elements (e.g., strain sensors or strain gauges) at a distal end of a medical instrument shaft to measure strain imparted to the medical instrument. The measured strain can be used to determine the force imparted to the medical instrument and as input upon which the desired haptic feedback may be generated. Typically, the force sensor unit is calibrated at time of instrument manufacture. This calibration establishes a zero-offset for the force sensing function of the medical instrument—the force sensor unit output that provides an indication that no force is applied to the instrument. During the lifecycle of the medical instrument, however, the zero-offset can shift so that on a condition in which no force is applied to the instrument, the force sensing unit erroneously indicates that a force is applied. For example, the medical instrument is subjected to reprocessing procedures following use that can include exposing the medical instrument, or portions thereof, to relatively high temperatures. This exposure can affect the force sensor unit, resulting in a shift in the zero-offset for the medical instrument. The shift in the zero-offset may, in turn, affect the accuracy of the measured strain used to determine the force imparted to the medical instrument and as input upon which the desired haptic feedback can be generated. Accordingly, it is desirable to determine a correct zero-offset for the medical instrument immediately prior to the medical instrument being used in a surgical procedure in order to provide accurate haptic feedback based on an accurate measure of the strain imparted to the medical instrument. In view of the aforementioned, the art is continuously seeking new and improved systems and methods for control of a surgical system based on the accurate measurement of the strain imparted to the medical instrument. SUMMARY This summary introduces certain aspects of the embodiments described herein to provide a basic understanding. This summar