Method and system for controlling flexible devices in presence of abnormal sensor signals

Abstract

To provide a computer-assisted medical system.SOLUTION: A computer-assisted medical system includes a flexible catheter configured to articulate, an actuator disposed at a proximal portion of the flexible catheter, an actuator sensor, and an articulation sensor. The actuator is configured to actuate the flexible catheter. The actuator sensor is configured to provide actuator sensor signals representing movement of the actuator. The articulation sensor is configured to provide articulation sensor signals representing articulation of the flexible catheter. The computer-assisted medical system includes a controller coupled to the actuator and configured to, based on detecting an abnormality of a first articulation sensor signal, determine an articulation estimate of the flexible catheter based on a model of the flexible catheter applied to a first actuator sensor signal, and control the actuator based on the articulation estimate.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 62 / 906,713, filed September 26, 2019, which is incorporated herein by reference in its entirety.

[0002] The examples described herein relate to improved robotic-assisted and / or medical devices, systems, and methods. [Background technology]

[0003] Flexible devices may be used to perform tasks at worksites, such as when the worksites are accessible through one or more orifices (e.g., one or more openings in a person, animal, machine, etc.). For example, minimally invasive medical procedures may be performed through the orifices to reduce the amount of tissue damaged during the medical procedure, thereby reducing patient recovery time, discomfort, and adverse side effects. The orifices may be natural orifices or surgical incisions in the patient's anatomy. An operator (e.g., a physician, physician's assistant, surgeon, etc.) may insert minimally invasive medical instruments (including surgical, diagnostic, therapeutic, and / or biopsy instruments) through the orifices to reach target tissue locations. Flexible and / or steerable elongate devices, such as flexible catheters, may be used to reach regions of interest within the patient's anatomy via anatomical passageways. Operator control of such elongate devices may include management of multiple degrees of freedom, including insertion and retraction of the elongate device relative to the patient's anatomy, as well as steering the device. To address these and other challenges, versatile systems and methods for appliance control are needed. Summary of the Invention

[0004] In general, in one aspect, one or more embodiments relate to a computer-aided medical system having: a flexible catheter configured to articulate along degrees of freedom; an actuator disposed in a proximal portion of the flexible catheter, the actuator configured to actuate the flexible catheter along the degrees of freedom; an articulation sensor configured to provide an articulation sensor signal representative of articulation of the flexible catheter; an actuator sensor configured to provide an actuator sensor signal representative of movement of the actuator; and a controller coupled to the actuator, the controller configured to: based on detecting an anomaly in a first articulation sensor signal: determine an articulation estimate of the flexible catheter based on a model of the flexible catheter applied to the first actuator sensor signal; and control the actuator based on the articulation estimate.

[0005] In general, in one aspect, one or more embodiments relate to a non-transitory machine-readable medium including machine-readable instructions that, when executed by one or more processors associated with a medical system, cause the medical system to: acquire an articulation sensor signal from an articulation sensor, the articulation sensor signal representing articulation of a flexible catheter; acquire an actuator sensor signal from an actuator sensor, the actuator sensor signal representing movement of an actuator configured to drive articulation of the flexible catheter; and based on detecting an anomaly in a first articulation sensor signal: determine a articulation estimate based on a model of the flexible catheter applied to the first actuator sensor signal, and control the actuator based on the articulation estimate.

[0006] In general, in one aspect, one or more embodiments relate to a method of operating a medical system, comprising: acquiring an articulation sensor signal from an articulation sensor, the articulation sensor signal representing articulation of a flexible elongate device; acquiring an actuator sensor signal from an actuator sensor, the actuator sensor signal representing movement of an actuator configured to drive articulation of the flexible elongate device; and based on detecting an anomaly in a first articulation sensor signal, switching to an actuator feedback control mode comprising: determining an articulation estimate based on a model of the flexible elongate device applied to the first actuator sensor signal; and controlling the actuator based on the articulation estimate.

[0007] Other examples will become apparent from the following description and appended claims. [Brief explanation of the drawings]

[0008] [Figure 1] 1 illustrates a schematic diagram of a computer-assisted medicine system, according to one or more embodiments.

[0009] [Figure 2] 1 illustrates an example of a computer-assisted medical system, according to one or more embodiments.

[0010] [Figure 3] 1 illustrates an example of a manipulator assembly including an instrument and a manipulator arm that holds the instrument, according to one or more embodiments.

[0011] [Figure 4] 1 illustrates an example of an instrument manipulator including a catheter assembly, according to one or more embodiments.

[0012] [Figure 5A]1 illustrates a schematic diagram of an example computer-assisted medical system including a flexible catheter, according to one or more embodiments.

[0013] [Figure 5B] 1 illustrates a schematic diagram of an example computer-assisted medical system including a flexible catheter, according to one or more embodiments.

[0014] [Figure 6] 1 illustrates a medical scenario in accordance with one or more embodiments.

[0015] [Figure 7] 1 illustrates an exemplary method for controlling a flexible catheter in a computer-assisted medical system, according to one or more embodiments.

[0016] [Figure 8] 1 illustrates an exemplary method for controlling a flexible catheter in a computer-assisted medical system, according to one or more embodiments.

[0017] [Figure 9] 1 illustrates an exemplary method for controlling a flexible catheter in a computer-assisted medical system, according to one or more embodiments.

[0018] [Figure 10] 1 illustrates an exemplary method for performing system identification to obtain a model for controlling a flexible catheter in a computer-assisted medical system, according to one or more embodiments.

[0019] [Figure 11] 1 illustrates an example implementation according to one or more embodiments.

[0020] [Figure 12] 10 illustrates an example of the performance of an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0021] Specific embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings, in which like elements in the various figures are designated with the same reference numerals for consistency.

[0022] In the following detailed description of embodiments of the present disclosure, numerous specific details are set forth. However, it will be apparent to those skilled in the art that some embodiments may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0023] Throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as adjectives of elements (i.e., any noun in the application). The use of ordinal numbers does not imply or create a particular order of elements, nor does it limit an element to only a single element, unless expressly disclosed, such as by the use of "before," "after," "single," and other such terms. Rather, the use of ordinal numbers is to distinguish between elements. As an example, a first element is distinct from a second element, and a first element may include more than one element and may follow (or precede) a second element in the order of elements.

[0024] While some of the examples described herein refer to medical procedures and medical tools, the examples described herein may apply to medical and non-medical procedures and tools. For example, the tools, systems, and methods described herein may be used for non-medical purposes, including industrial applications, general robotic applications, and sensing or manipulating non-tissue workpieces. Other exemplary applications include cosmetic enhancement, imaging of human or animal anatomy, collecting data from human or animal anatomy, assembling or disassembling systems, and training medical or non-medical personnel. Additional exemplary applications include use for procedures on tissue removed from a human or animal anatomy (without returning to the human or animal anatomy), and use for performing procedures on human or animal cadavers. Furthermore, these techniques may also be used for medical therapeutic or diagnostic procedures, with or without a surgical aspect.

[0025] Generally, embodiments of the present disclosure may enable responding to one or more fault conditions in a computer-aided medical system including a flexible catheter. More specifically, a control method may be used to address a temporary fault condition. The fault condition may introduce an error into a feedback signal obtained from an articulation sensor, e.g., a sensor measuring the articulation (e.g., geometry) of the flexible catheter. While the error exists, the feedback signal may be unsuitable or inappropriate for closed-loop control. While the feedback signal may be used to control the position and / or movement of the flexible catheter under regular operating conditions, when a fault condition exists, the control method may rely on an alternative feedback signal. The alternative feedback signal may be based on an actuator sensor signal, e.g., a sensor signal representing the movement of an actuator that drives the articulation. For example, the actuator sensor signal may be processed by a simulation model of the flexible catheter to obtain an estimate of the actual articulation. This estimate may then be used as the alternative feedback signal to control the articulation.

[0026] Fault conditions that may render the feedback signal obtained from the articulation sensor unusable or less useful may include mechanical vibration. The fault condition(s) may be time-limited. For example, mechanical vibration may occur temporarily during insertion or removal of a tool into or from a flexible catheter. Thus, an alternative feedback signal may be temporarily used for control until an appropriate feedback signal obtained from the articulation sensor returns. Thus, disruptions that would otherwise result from deactivating control of articulation may be avoided.

[0027] Referring now to the drawings, wherein like reference numerals represent like parts throughout the several views, FIG. 1 shows a simplified diagram of a computer-aided medical system (100) according to one or more embodiments. The computer-aided medical system (100) may be suitable for use in, for example, surgical, diagnostic, therapeutic, and / or biopsy procedures. While some embodiments are provided herein with respect to such procedures, any reference to medical (e.g., surgical) instruments and methods is non-limiting. The systems, instruments, and methods described herein may be used on animals, human cadavers, animal remains, portions of the human or animal anatomy, non-surgical diagnostics, as well as industrial systems and general robotic or teleoperated systems.

[0028] 1, a computer-assisted medical system (100) generally includes a manipulator assembly (102) for manipulating a medical instrument (104) to perform various procedures on a patient (P) in accordance with one or more embodiments of the present invention. The medical instrument (104) may include a flexible catheter and may be steered as it is extended into an internal site within the body of the patient (P).

[0029] The manipulator assembly (102) and instrument (104) may be teleoperated, non-teleoperated, or a hybrid teleoperated and non-teleoperated assembly having selectable degrees of freedom of movement that may be motorized and / or teleoperated, and selectable degrees of freedom of movement that may be non-motorized and / or non-teleoperated. The manipulator assembly (102) may be mounted to an operating table (T) or a main support (114) (e.g., a cart, stand, secondary table, and / or the like). A master assembly (106) allows an operator O (e.g., a surgeon, clinician, or physician) to view the intervention site and control the manipulator assembly (102), including the instrument (104).

[0030] The master assembly 106 may be located in an operator console that may be located in the same room as the operating table (T), such as to the side of the operating table where the patient (P) is located. However, it should be understood that the operator (O) may be located in a different room from the patient (P) or in a different building entirely. The master assembly 106 may include one or more controllers for controlling the manipulator assembly 102. The controllers may include any number of different input devices, such as joysticks, trackballs, data gloves, trigger guns, hand-operated controllers, voice recognition devices, body movement or presence sensors, etc. To give the operator (O) a strong sense of direct control over the instrument (104), the controllers may have the same degrees of freedom as the associated medical instrument (104). In this way, the controllers give the operator (O) a sense of telepresence or the perception that the controllers are integral with the medical instrument (104).

[0031] In one or more embodiments, the manipulator assembly (102) supports the medical instrument (104), including a flexible catheter, and may include one or more non-servo controlled links (e.g., one or more links that can be manually positioned and locked in place, commonly referred to as a setup structure) and / or one or more servo controlled links (e.g., one or more powered links that can be controlled in response to commands from a control system) and kinematic structure of the manipulator. The manipulator assembly (102) may include multiple actuators (e.g., motors) that drive the medical instrument (104) in response to commands from a control system (e.g., control system (112)).

[0032] The actuator may include a drive system that, when coupled to the medical instrument 104, can advance the medical instrument 104 naturally or through a surgically created anatomical opening. Other drive systems can move the distal end of the medical instrument 104 in one or more degrees of freedom, which may include at least linear insertion / retraction motion and one or more articulation motions for orienting the instrument, as described in detail below. Additionally, the actuator may be used to actuate an articulatable end effector of the medical instrument 104 to grasp tissue within the jaws of a biopsy device, etc. Actuator sensors (e.g., resolvers, encoders, potentiometers, and other mechanisms) can provide sensor data to the medical system 100 describing the position, rotation, and / or orientation of the motor shaft. This actuator sensor data can be used to determine the movement of an object manipulated by the actuator. The actuator sensors may include a proximal sensor located more proximal than other sensors used to measure distal portions of or along the medical instrument.

[0033] The computer-aided medical system 100 may include a sensor system 108 having one or more subsystems for receiving information related to the instruments (including the flexible catheter) of the manipulator assembly 102. Such subsystems may include a position / location sensor system (e.g., an electromagnetic (EM) sensor system); a shape sensor system for determining the position, orientation, speed, velocity, attitude, and / or shape of one or more segments along the distal portion and / or flexible body that may comprise the flexible catheter housing the instrument 104; and / or a visualization system for capturing images from the distal end of the instrument 104. The one or more sensors of the sensor system 108 may include a distal sensor used to make measurements at the distal portion of and / or along the flexible catheter housing the instrument.

[0034] In one or more embodiments, the computer-aided medical system (100) also includes a display system (110) for displaying images or representations of the surgical site and medical instrument (104), including the flexible catheter, generated by the subsystems of the sensor system (108) and recorded pre- or intra-operatively using image data from imaging techniques and / or real-time images, such as computed tomography (CT), magnetic resonance imaging (MRI), fluoroscopy, thermography, ultrasound, optical coherence tomography (OCT), thermal imaging, impedance imaging, laser imaging, nanotube x-ray imaging, endoscopic images, etc. The pre- or intra-operative image data may be presented as two-dimensional, three-dimensional, or four-dimensional (e.g., including time-based or velocity-based information) images and / or as images from models created from the pre- or intra-operative image datasets. The display system (110) and the master assembly (106) may be oriented to allow an operator (O) to control the medical instrument (104) and the master assembly (106) with a telepresence perception.

[0035] Continuing with FIG. 1 , the computer-assisted medical system (100) may also include a control system (112). The control system (112) includes at least one memory and at least one computer processor (not shown) for controlling between the medical instrument (104), the master assembly (106), the sensor system (108), and the display system (110). The control system (112) also includes programmed instructions (e.g., a non-transitory machine-readable medium storing instructions) for implementing some or all of the methods described below, including instructions for operating in the presence of unreliable or unreliable sensor signals, as described with reference to the flowcharts of FIGS. 7, 8, 9, and 10. While the control system (112) is shown as a single block in the simplified schematic diagram of FIG. 1 , the system may include multiple data processing circuits, with one portion of the processing optionally performed on or adjacent to the manipulator assembly (102), another portion of the processing performed in the master assembly (106), etc. Any of a wide variety of centralized or distributed data processing architectures may be utilized. Likewise, the programmed instructions may be implemented as several separate programs or subroutines, or they may be integrated into some other aspect of the systems described herein.

[0036] In one or more embodiments, the control system 112 may receive force and / or torque feedback from the medical instrument 104. In response to the feedback, the control system 112 may send signals to the master assembly 106. In some examples, the control system 112 may send signals to one or more actuators of the manipulator assembly 102 instructing them to move the medical instrument 104 (e.g., move a flexible catheter).

[0037] Any suitable conventional and / or specialized actuators may be used to actuate the links or segments of the manipulator assembly 102 and / or the instrument 104. One or more actuators may be separate from the manipulator assembly 102 or may be integral with the manipulator assembly 102.

[0038] In one or more embodiments, the control system 112 may include a hierarchical control architecture. The hierarchical control architecture may include a supervisory state machine, a mid-level controller, and a servo controller (feedback controller) for each actuator. The supervisory state machine may be event-driven. Based on the event, the supervisory state machine may send behavioral primitives to the mid-level controller. The behavioral primitives may be high-level commands specifying an overall goal, such as a target configuration for the manipulator assembly 102. In response, the mid-level controller may issue servo commands to the servo controller to move the actuator. More specifically, the mid-level controller may perform numerical calculations to configure, initialize, and reset the servo controller based on the behavioral primitives. For example, the mid-level controller may send parameters specifying a position and / or trajectory to the servo controller. The servo controller may then drive the actuator based on the command received from the mid-level controller. The servo controller may report to the supervisory state machine to indicate, for example, whether an operation was successfully executed according to the servo command. Further aspects of the control system (112) are described below with reference to Figures 7, 8, 9, and 10. In one or more embodiments, the supervisory state machine and mid-level controllers are low-latency. For example, a response to an event may be provided within 50 ms. Each of the servo controllers may operate a closed loop using proportional-integral-derivative (PID), proportional-derivative (PD), full-state feedback, sliding mode, and / or various other control schemes. Feedback signals for the servo controllers may be obtained, for example, from encoders or resolvers of the actuators controlled by the servo controllers. Alternatively, as described further below, the servo controllers may also rely on other sensors for feedback.More specifically, the servo controller for controlling the articulation (e.g., bending) of the flexible catheter may use signals from an articulation sensor, e.g., a bend sensor or a shape sensor, to control the articulation or bending of the flexible catheter. A more detailed description of various aspects of the control system (112) is provided below with reference to Figures 7, 8, 9, and 10.

[0039] Continuing with FIG. 1 , the control system 112 can operate in various modes in addition to the servo control mode described above. For example, the control system 112 can control one or more of the joints of the manipulator assembly described below to float. A floating joint can be back-driven by an externally applied force without a control algorithm or by a damping force that counters a sufficient externally applied force. For example, a user can apply a force that meets one or more criteria (e.g., magnitude, direction, duration, frequency, etc.) to the distal link of the floating joint, causing the floating joint to backdrive. A floating joint can be further gravity compensated, especially if it floats in a degree of freedom affected by gravity (e.g., a vertical joint or a non-horizontal direction). Additionally, friction compensation can facilitate backdrive. Additionally or alternatively, a floating joint can be controlled to impose other characteristics, such as a level of damping.

[0040] In one or more embodiments, floating joints can be particularly beneficial during a setup phase, allowing an assistant to manually position and / or orient the manipulator assembly (102) by backdriving the floating joint during the setup phase in preparation for performing a procedure using the instrument (104). Multiple control modes can be combined during operation of the manipulator assembly; for example, some joints can be position controlled to resist or rebound from external articulation motion of those joints, while other joints can be floating to facilitate external articulation motion of those other joints.

[0041] The control system (112) may optionally include a virtual visualization system to provide navigational assistance to the operator (O) when controlling the medical instrument (104) during an image-guided surgical procedure. Virtual navigation using the virtual visualization system may be based on referencing pre- or intra-operatively acquired datasets of the anatomical passageway.

[0042] During a virtual navigation procedure, the sensor system (108) can be used to calculate the approximate position of the medical instrument (104) relative to the patient's (P) anatomy. This position can be used to generate both macro-level (external) tracking images of the patient's (P) anatomy and virtual internal images of the patient's (P) anatomy. The system can include one or more electromagnetic (EM), fiber optic, and / or other sensors to register and display the medical instrument with pre-operatively recorded surgical images, such as those from a virtual visualization system. For example, PCT Publication WO 2016 / 191298 (published December 1, 2016) (disclosing "Systems and Methods of Registration for Image-Guided Surgery"), which is incorporated herein by reference in its entirety, discloses an exemplary system.

[0043] The computer-assisted medical system 100 may further include optional manipulation and support systems (not shown), such as a lighting system, a steering control system, an irrigation system, and / or a suction system. In some embodiments, the computer-assisted medical system 100 may include more than one manipulator assembly and / or more than one master assembly. The exact number of remotely operated manipulator assemblies may depend, among other things, on the surgical procedure and spatial constraints within the operating room.

[0044] In some embodiments, the manipulator assembly (102), control system (112), sensor system (108), and display system (110) may all be supported by or integrated into the support structure (114). Alternatively, one or more components (e.g., the manipulator assembly (102), control system (112), sensor system (108), and / or display system (110)) may be attached to the operating table (T) or integrated into the master assembly (106).

[0045] FIG. 2 illustrates an example of a computer-assisted medical system (200) according to one or more embodiments. The computer-assisted medical system (200) may include a master control unit (220) and a system cart (214) that supports a manipulator assembly (202) and a display system (216). The manipulator assembly (202) may be configured to support and position an elongate device, such as a flexible catheter (222). Various elongate devices are described in PCT / US18 / 43041 (filed July 20, 2018) (disclosing "Flexible elongate device systems and methods"), which is incorporated herein by reference in its entirety. The system cart (214) supports a monitor support arm (210) and a display system (216) including display monitors (216a, 216b).

[0046] The computer-assisted medical system (200) of FIG. 2 also includes a master control (220) according to one or more embodiments, some aspects of which are described above with respect to the master assembly (106). The master control (220) may include various input controls for use by an operator (e.g., operator (O), FIG. 1 ) to interactively control the operation of the manipulator assembly (202), e.g., the functions performed by the instrument manipulator (206). In one or more embodiments, the master control (220) includes a scroll wheel and a trackball on its surface, which allow the operator to control aspects of the computer-assisted medical system (200). In an exemplary implementation, the scroll wheel can be rotated forward or backward to control the advancement / insertion or retraction of a medical instrument (e.g., flexible catheter (222)) relative to a patient's anatomy, and the trackball can be rotated in various directions by the operator to steer the position of the distal end portion and / or distal tip of the flexible catheter (222), e.g., to control bending or articulation. Various systems and methods related to motion control consoles are described in PCT / US18 / 44419 (filed July 30, 2018) (related to "Systems and methods for safe operation of a device") and U.S. patent application Ser. No. 16 / 049,640 (filed July 30, 2018) (disclosing "Systems and methods for steerable elongate device"), which are incorporated herein by reference in their entireties.

[0047] 3 illustrates a manipulator assembly (202) including an instrument manipulator (206) coupled to a support structure (204) in accordance with one or more embodiments of the present invention. The links of the support structure (204) may include one or more non-servo-controlled links (e.g., that may be manually positioned and locked in place) and / or one or more servo-controlled links (e.g., powered links that may be controlled in response to commands from a control system). The support structure (204) provides adjustments to position the instrument manipulator (206) in an optimal position and orientation and / or to position the flexible catheter (222) to optimally position the flexible catheter (222) relative to the patient's anatomy or other medical device. For example, the support structure (204) may provide rotation (E1) about axis (E), extension / retraction (E2) along axis (E), rotation (D1) about axis (D), and rotation (C1) about axis (C), and rotation (B1) about axis (B) to position the instrument manipulator (206) in a desired position relative to the table (T), medical device, and / or patient (P).

[0048] In some embodiments, the optimal position and orientation may include alignment of the instrument manipulator 206 with the patient's anatomy, for example, for optimal positioning of the flexible catheter 222 to minimize friction of the flexible catheter 222 disposed within the patient's anatomy (e.g., an anatomical orifice, the patient's vasculature, the patient's intraluminal passageway, etc.) or within a medical instrument coupled to the patient's anatomy (e.g., a cannula, a trocar, an endotracheal tube (ETT), a laryngoesophageal mask airway (LMA), etc.). In other embodiments, the optimal position and orientation of the instrument manipulator 206 may additionally or alternatively include optimizing operator (O) ergonomics by providing sufficient operator workspace and / or ergonomic access to the flexible catheter when utilizing various medical tools, such as needles, graspers, scalpels, grippers, ablation probes, visualization probes, and / or the like, with the flexible catheter 222.

[0049] The instrument manipulator (206) may further be configured to provide remote, robotic, or other forms of controlled or manual translation A1 along axis A to provide for insertion and retraction of the flexible catheter (222) relative to the patient's anatomy.

[0050] Each adjustment (e.g., A1, B1, C1, D1, E1, and E2) can be actuated either by robotic control or manual intervention by an operator. For example, in one embodiment, each rotational or linear adjustment can be maintained in a fixed configuration using brakes, such that pressing one or more buttons and switches releases one or more corresponding brakes, allowing the operator to manually position the instrument manipulator. Additionally or alternatively, one or more adjustments can be controlled by one or more actuators (e.g., motors), such that the operator can use a button or switch to activate a motor to alter the support structure 204 and / or instrument manipulator 206 to position the manipulator assembly 202 in a desired configuration, typically to provide an optimal position and orientation of the instrument manipulator 206.

[0051] Continuing with FIG. 3 , the manipulator assembly (202) may include various control buttons (324, 326, 328, 330) that may be used for various purposes, such as unlocking the support structure (204) for free movement and adjustment of the coupling links to allow manual translational adjustments C1, D1, E1, and / or E2 and / or linear adjustment A1 by an operator rather than by robotic control for inserting / retracting a medical instrument (e.g., flexible catheter (222)). In one or more embodiments, for safety purposes, the instrument manipulator (206) may be manually movable only in one direction along linear axis A, such as retraction, but not in the direction along linear axis A corresponding to insertion of a medical instrument, to prevent the operator from inadvertently or undesirably advancing the medical instrument into the patient's anatomy, which could cause harm to the patient. In another example, robotic or manual control of rotational movement B1 about axis B may be enabled by pressing a switch. Additionally, one or more buttons may be used to control visual indicators, markers, and / or images shown on the monitors (216a, 216b) and / or touch screens on the master control unit (220).

[0052] FIG. 4 illustrates an example of an instrument manipulator (406), which may be substantially similar to instrument manipulator (206). The instrument manipulator (406) may include a base (404), an insertion stage (402), and an instrument carriage (408) to which a catheter assembly (410) is coupled. In one or more embodiments, the instrument manipulator (406) provides for insertion and retraction of the catheter assembly (410) relative to the patient's anatomy by telescopingly moving the instrument carriage (408) and the insertion stage (402) relative to the base (404) and along a linear axis A, as further shown in FIG. 6 . Thus, the instrument manipulator (406) provides an insertion degree of freedom for insertion and retraction of a flexible catheter (410a) along the linear axis A. In a medical scenario, insertion may advance the flexible catheter (410a) into the patient's anatomy, and retraction may withdraw the flexible catheter (410a) from the patient's anatomy.

[0053] The base 404 includes a shaft portion 404a and a main portion 404b. As described in more detail below, the shaft portion 404a removably couples to a device connector or swivel connector 418 that receives a flexible catheter 410a. The insertion stage 402 is coupled to and translates along the main portion 404b of the base 404. The instrument carriage 408 is coupled to and translates along the insertion stage 402. The catheter assembly 410 may include the flexible catheter 410a and a control assembly 410b. The instrument carriage 408 couples to the control assembly 410b at an instrument interface 414 of the instrument carriage 408. The instrument manipulator 406 also couples to a probe assembly 416, which includes a probe 416b and a probe connector 416a. The probe assembly 416 can be inserted into a working lumen of the flexible catheter 410a through a connector 412 on the control assembly 410b and extend through the flexible catheter 410a. The probe 416b can include, for example, a scope assembly that provides an image of the surgical site. The instrument carriage 408 can include electronic and optical components that provide the probe 416b with endoscopic capabilities. In some embodiments, the probe assembly 416 can be separated from the instrument manipulator 406 and the flexible catheter control assembly 410b and removed from the catheter assembly 410a. Alternative instruments such as biopsy needles, ablation tools, and other flexible instruments may be coupled to instrument manipulator (406) and / or catheter assembly (410) through the working lumen of flexible catheter (410a).

[0054] Continuing with FIG. 4 , the device connector or swivel connector 418 may include a manipulator interface that may be removably coupled to the base 404, a distal end that may be removably coupled to a patient medical device 420, such as an endotracheal tube, and a proximal end that may receive the flexible catheter 410 a. The patient medical device 420 (e.g., an endotracheal tube, laryngeal mask airway, cannula, etc.) may be secured to the patient's anatomy to facilitate insertion of various medical devices into the patient's anatomy. For example, the patient medical device 420 may be an endotracheal tube (P) inserted into the patient's mouth and trachea to provide a conduit for the flexible catheter 410 a that will be navigated within the patient's lungs to facilitate imaging, biopsy, and / or treatment. Various systems and methods related to device connectors are described in PCT / US2018 / 017085 (filed February 6, 2018) (disclosing "Systems and methods for coupling components of a medical system"), which is incorporated herein by reference in its entirety. In some embodiments, the flexible catheter 410a passes through a catheter guide 422, which is a selectively collapsible and extendable device that supports the length of the flexible catheter 410a during movement of the instrument carriage 408. An unguided flexible catheter 410a may buckle in areas without lateral support, for example, in the space between the instrument interface 414 and the device connector 418. To avoid buckling, the catheter guide 422 may act as an anti-buckling guide by providing lateral support to the flexible catheter 410a. Various systems and methods related to catheter guides are described in PCT / US2017 / 041160 (filed July 7, 2017) (disclosing "Guide apparatus for delivery of an elongate device and methods of use"), which is incorporated herein by reference in its entirety.

[0055] FIG. 5A is a simplified diagram of a computer-assisted medical system (500) according to one or more embodiments. While the previous figures primarily illustrated aspects of the computer-assisted medical system (100) and instrument manipulator (206) overall, FIGS. 5A and 5B primarily illustrate aspects related to a flexible catheter (502). The computer-assisted medical system (500) may be similar to the computer-assisted medical system (100) previously introduced with reference to FIG. 1. The computer-assisted medical system (500) may include a flexible catheter (502) (more generally, an elongated, flexible device) on an instrument interface (504). The instrument interface may be a physical interface that allows the flexible catheter to be coupled to other components of the computer-assisted medical system (500). In the example of FIG. 4, the instrument interface may be part of the instrument carriage (408).

[0056] In one or more embodiments, the flexible catheter 502 includes a flexible body 516 having a proximal portion 517 and a distal portion 518 (e.g., a tip portion). The flexible body 516 may have an outer diameter of approximately 3 mm. Other flexible body outer diameters may be larger or smaller.

[0057] The flexible body 516 may include a lumen or channel 521 sized and shaped to receive a medical instrument 526, as shown in FIG. 5B , which is a simplified diagram of the flexible body 516 with an extended medical instrument 526, according to one or more embodiments. The medical instrument 526 may be used for procedures including, but not limited to, surgery, biopsy, ablation, illumination, irrigation, and / or aspiration. For example, the medical instrument 526 may be a flexible bronchial instrument, such as a bronchoscope or bronchial catheter, for use in lung examination, diagnosis, biopsy, or treatment. The medical instrument 526 may also be suitable for navigation and treatment of other tissues through natural or surgically created connecting passageways in any of a variety of anatomical systems, including the colon, intestines, kidneys and calyces, brain, heart, circulatory system, including vasculature, and the like.

[0058] The medical instrument 526 can be deployed through the lumen 521 of the flexible body 516 and used at a target location within the anatomy. The medical instrument 526 can include, for example, an image capture probe, a biopsy instrument, a laser ablation fiber, and / or other surgical, diagnostic, or therapeutic tool. The medical tool can include an end effector having a single working member, such as a scalpel, a blunt blade, an optical fiber, an electrode, etc. Other end effectors can include, for example, forceps, graspers, scissors, clip appliers, and / or the like. Other end effectors can also include electrically activated end effectors, such as electrosurgical electrodes, transducers, sensors, etc. In one or more embodiments, the medical instrument 526 is a biopsy instrument that can be used to remove sample tissue or sample cells from a target anatomical location. The medical instrument 526 can be used with an image capture probe that is also within the flexible body 516.

[0059] Returning to FIG. 5A , the medical instrument (526) may be an image capture probe including a distal portion with a stereoscopic or monoscopic camera at or near the distal portion (518) of the flexible body (516) to capture images that are processed for display by the visualization system (531) and / or provided to the tracking unit (530) to support tracking of one or more of the distal portion (518) and / or segments (524). The image capture probe may include a cable coupled to the camera for transmitting the captured image data. In some examples, the image capture instrument may be a bundle of optical fibers, such as a fiberscope, that couples to the visualization system (531). Alternatively, the medical instrument (526) may itself be the image capture probe. The medical instrument (526) may be advanced from an opening in the lumen (521) to perform a procedure and then retracted back into the lumen when the procedure is completed. The medical instrument (526) may be removed from the proximal portion (517) of the flexible body (516) or from another optional instrument port (not shown) along the flexible body (516).

[0060] In one or more embodiments, one or more actuators (506) may be used to actuate the flexible catheter (502). For example, one actuator may be used to actuate the flexible catheter along its insertion degree of freedom. As described further below, additional actuators may be used to actuate the catheter along one or more articulation degrees of freedom. In one or more embodiments, the flexible body (516) houses pull wires, linkages, or other steering controls (540) extending between the actuators (506) and the distal portion (518) to controllably bend the distal portion (518), as shown, for example, by the dashed line depiction (519) of the distal portion (518). In one or more embodiments, at least four pull wires (540) actuated by at least four actuators (506) are used to provide independent up / down steering to control the pitch of the distal portion (518) and left / right steering to control the yaw of the distal portion (518). Steerable elongate devices are described in detail in U.S. Patent Application No. 13 / 274,208 (filed October 14, 2011) (disclosing "Catheter with Removable Vision Probe"), which is incorporated herein by reference in its entirety. More detailed information regarding control systems for controlling flexible catheters is provided in U.S. Patent Application No. 62 / 671,758 (disclosing "Control Mechanism of a Catheter Control System"), which is incorporated herein by reference in its entirety. In one or more embodiments, actuator (506) can be removably coupled to flexible catheter (502) via instrument interface (504). Actuator (506) can be, for example, a servo motor, a hydraulic and / or pneumatic actuator, or the like. Referring to FIG. 4, actuator (506) can be housed, for example, in control assembly (410b) of instrument carriage (408).

[0061] Continuing with FIG. 5A, when the actuator applies torque, a capstan (not shown) attached to the drive shaft of the actuator may be rotated. This rotation causes further winding or unwinding of the pull wires (540) around the capstan, thereby actuating the pull wires to steer the distal end portion (518) of the flexible catheter (502). Each pull wire (540) may be driven by a separate actuator. Thus, the tension in each of the pull wires (540) may be individually controlled.

[0062] Monitoring the rotational position (e.g., angle) and / or rotational speed of the capstan or actuator can be used to provide an indication of how much the pull wire 540 is released or pulled. Thus, the capstan's rotational angle and / or rotational speed and / or torque applied by the actuator to drive the capstan can provide useful feedback for the steering to be applied to the distal portion 518. The direction in which the distal portion 518 bends can depend on the placement of the pull wire 540 relative to other pull wires that also contribute to steering. Actuator sensors 508, such as resolvers, encoders, potentiometers, and other mechanisms, can be used to track the rotation and / or orientation of the capstan and / or actuator. Additionally, the actuator's motor current can be used to calculate the force and / or torque applied to the pull wire 540.

[0063] When configured to operate as antagonists, pairs of actuators 506 (e.g., one pair of actuators for pitch control of distal portion 518 and one pair of actuators for yaw control of distal portion 518) may be used to articulate distal portion 518 and control the stiffness of flexible body 516. Additionally, by maintaining a minimum level of tension in pull wires 540, slack in the pull wires 540 may be avoided. Releasing or reducing the force on the pull wires 540 of the flexible catheter 502 may result in a corresponding reduced stiffness or stiffness in the flexible catheter 502. Similarly, applying or increasing a pulling force on the pull wires 540 of the flexible body 516 may result in an increase in the stiffness or stiffness of the flexible catheter 502. For example, the material of the flexible body 516 may become stiffer with multiple steering pull wires being pulled simultaneously. The stiffness or stiffness of the flexible catheter 502 may be a closed-loop stiffness or stiffness controlled by a control system. Examples of closed-loop catheter control systems and methods are described, for example, in U.S. Patent Application No. 13 / 274,198, filed October 14, 2011 (disclosing "Catheters with Control Modes for Interchangeable Probes"), which is incorporated herein by reference in its entirety.

[0064] In one or more embodiments, the computer-assisted medical system (500) may include a tracking unit (530) for determining the position, orientation, speed, velocity, pose, and / or shape of the distal portion (518) and / or one or more segments (524) along the flexible body (516) using one or more sensors and / or imaging devices, as described in further detail below. The tracking unit (530) may be implemented as hardware, firmware, software, or a combination thereof. One or more aspects of the tracking unit may be executed by the processor(s) of the control system (112) of FIG. 1 .

[0065] The tracking unit 530 may track one or more of the distal portion 518 and / or the segments 524 using an articulation sensor, such as a shape sensor 522. The shape sensor 522 may include an optical fiber aligned with the flexible body 516 (e.g., disposed within an internal channel (not shown) of the flexible body 516 or attached to the exterior). In one embodiment, the optical fiber has a diameter of approximately 200 μm. The fiber diameter may be larger or smaller without departing from this disclosure. The optical fiber of the shape sensor 522 forms a fiber optic bend sensor for determining the shape of the flexible body 516. An optical fiber including a fiber Bragg grating (FBG) may be used to provide strain measurements in the structure in one or more dimensions. Various systems and methods for monitoring the shape and relative position of optical fibers in three dimensions are described in U.S. patent application Ser. No. 11 / 180,389, filed July 13, 2005 (disclosing "Fiber optic position and shape sensing device and method relating thereto"); U.S. patent application Ser. No. 12 / 047,056, filed July 16, 2004 (disclosing "Fiber-optic shape and relative position sensing"); and U.S. Patent No. 6,389,187, filed June 17, 1998 (disclosing "Optical Fiber Bend Sensor"), all of which are incorporated herein by reference in their entireties. Other suitable strain sensing techniques, such as Rayleigh scattering, Raman scattering, Brillouin scattering, and fluorescence scattering, may be used without departing from this disclosure. Alternatively, the shape of the elongated device may be determined using other techniques. For example, the history of the orientation of the distal end of flexible body 516 may be used to reconstruct the shape of flexible body 516 over a time interval.

[0066] Continuing with FIG. 5A , the tracking unit 530 may receive a raw signal from the shape sensor 522. In one or more embodiments, the tracking unit 530 processes the raw signal to obtain information regarding the shape of the flexible body 516. The obtained information may relate to the shape of the distal portion 518 and / or one or more segments 524 along the flexible body 516. In combination with the shape sensor 522, the tracking unit 530 may provide feedback, for example, regarding the articulation of the flexible catheter 502. The tracking unit may also be configured to detect abnormalities in the shape sensor 522 and / or the tracking unit itself. For example, the tracking unit 530 may detect noise (such as vibrations) in the raw signal. The tracking unit 530 may also detect poor raw signals associated with contaminated or poorly attached fiber optic connectors to the shape sensor 522.

[0067] In some embodiments, the tracking unit (530) may optionally and / or additionally track the distal portion (518) using a position sensor system (520). The position sensor system (520) may use any suitable sensing technology or combination of sensing technologies, such as, for example, electromagnetic technology. An electromagnetic (EM) sensor system may include one or more conductive coils that may be exposed to an externally generated electromagnetic field. Each coil of such an EM sensor system used to implement the position sensor system (520) then generates an induced electrical signal having characteristics that depend on the coil's position and orientation relative to the externally generated electromagnetic field. In some embodiments, the position sensor system (520) may be configured and positioned to measure six degrees of freedom, e.g., three position coordinates X, Y, Z and three direction angles indicative of the pitch, yaw, and roll of a fiducial, or five degrees of freedom, e.g., three position coordinates X, Y, Z and two direction angles indicative of the pitch and yaw of a fiducial. Further description of position sensor systems is provided in U.S. Pat. No. 6,380,732, filed Aug. 11, 1999 (disclosing "Six-Degree of Freedom Tracking System Having a Passive Transponder on the Object Being Tracked"), which is incorporated herein by reference in its entirety. The position sensor system (520) can be used as an articulation sensor. For example, multiple sensors (520), such as EM sensors, can be positioned along the flexible catheter 502 (e.g., in multiple segments 524), and the articulation (e.g., shape) of the flexible catheter 502 can be determined based on the detected positions of the sensors (520).

[0068] Information from the tracking unit 530 may be sent to a navigation system 532, where it may be combined with information from the visualization system 531 and / or preoperatively derived models to provide real-time position information to a physician or other operator. The real-time position information may be displayed on the display system 110 of FIG. 1 for use in controlling the computer-aided medical system 500. In some examples, the control system 112 of FIG. 1 may use the position information as feedback to position the computer-aided medical system 500. Various systems for using fiber optic sensors to register and display surgical instruments with surgical images are provided in U.S. patent application Ser. No. 13 / 107,562, filed May 13, 2011, which discloses "Medical System Providing Dynamic Registration of a Model of an Anatomic Structure for Image-Guided Surgery," the entire contents of which are incorporated herein by reference.

[0069] FIG. 6 diagrammatically illustrates a medical scenario including a side view of patient coordinate space, according to one or more embodiments. The surgical scenario (600) may include a patient (P) positioned on a platform (602). An instrument carriage (606) is attached to an insertion stage (608), as also shown in FIG. 4 . The instrument carriage (606) may be used to control the insertion / retraction (e.g., movement along an insertion axis A) of a flexible catheter (610) into / from the anatomy of the patient (P), thereby establishing an insertion degree of freedom for the flexible catheter (610). The instrument carriage (606) may also be used to control the motion (e.g., articulation) of a distal portion (618) of the flexible catheter in multiple directions, including yaw and pitch. The instrument carriage (606) or the insertion stage (608) may include actuators, such as servo motors (not shown), that control the movement of the instrument carriage (606) along the insertion stage (608). Additionally, the instrument carriage (606) may include an actuator that controls the articulation of the distal portion (618) of the flexible catheter.

[0070] The flexible catheter 610 may be coupled to the instrument interface 612 described above with respect to Figures 4 and 5. The instrument interface 612 may be coupled and fixed to the instrument carriage 606. In one or more embodiments, the fiber optic shape sensor 614 provides information regarding the configuration of the flexible catheter 610, including, for example, the position and / or orientation of the distal portion 618 of the catheter 610. The position measurement device 620 may provide information regarding the position of the instrument interface 612 as it moves on the insertion stage 608 along a retraction and / or insertion axis A (e.g., along the central longitudinal axis of the instrument body), which establishes the insertion degree of freedom of the flexible catheter 610. The position measurement device 620 may include resolvers, encoders, potentiometers, and / or other sensors that determine the rotation and orientation of the drive shaft that controls the movement of the instrument carriage 606 and, therefore, the movement of the instrument interface 612. The insertion stage 608 may be linear, curved, or a combination thereof.

[0071] While Figures 1, 2, 3, 4, 5A, 5B, and 6 depict various configurations of components, other configurations may be used without departing from the scope of the present disclosure. For example, various components may be combined to create a single component. As another example, functions performed by a single component may be performed by two or more components. Furthermore, while the components are described in the context of a medical scenario, embodiments of the present disclosure may be equally applicable to other areas involving robotic manipulation, e.g., non-medical scenarios or systems. Embodiments of the present disclosure may be suitable for use in, for example, surgical, diagnostic, therapeutic, and / or biopsy procedures. While some embodiments are provided herein with respect to such procedures, any reference to medical or surgical instruments and methods is non-limiting. The systems, instruments, and methods described herein may be used with animals, human cadavers, animal cadavers, portions of the human or animal anatomy, non-surgical diagnostics, and industrial systems and general robotic or teleoperated systems. The systems, instruments, and methods may operate on or interact with any type of work site, rather than interacting with the anatomy of a patient or subject.

[0072] Figures 7, 8, 9, and 10 illustrate flowcharts according to one or more embodiments. One or more of the operations in Figures 7, 8, 9, and 10 may be performed by various components of a system as described above with reference to Figures 1, 2, 3, 4, 5A, 5B, and 6. These figures describe a particular manipulator assembly and a particular flexible catheter, and the manipulator assembly and flexible catheter have particular degrees of freedom. However, the methods described below are not limited to any particular configuration of manipulator assembly, flexible catheter, and / or degrees of freedom. Instead, the methods are applicable to any type of flexible catheter supported by a manipulator assembly used in any type of scenario.

[0073] Although the various operations in these flowcharts are presented and described sequentially, those skilled in the art will understand that some or all of the operations may be performed in a different order, combined, or omitted, and that some or all of the operations may be performed in parallel. Additional operations not shown in the flowcharts may also be performed. Furthermore, operations may be performed actively or passively. For example, some operations may be performed using polling or may be interrupt-driven in accordance with one or more embodiments of the present disclosure. As one example, a decision operation may not require a processor to process an instruction unless an interrupt is received to indicate that a condition exists in accordance with one or more embodiments of the present disclosure. As another example, a decision operation may be performed by performing a test, such as checking a data value to see if the value matches a condition tested in accordance with one or more embodiments of the present disclosure. Accordingly, the scope of the present disclosure is not limited to the specific configurations of operations shown in FIGS. 7, 8, 9, and 10.

[0074] The flowcharts in FIGS. 7, 8, 9, and 10 describe a method for addressing an anomaly (e.g., a temporary fault condition) according to one or more embodiments. The fault condition can introduce error into the feedback signal obtained from a sensor measuring the articulation motion of the flexible catheter. For example, the sensor signal of a shape sensor measuring the shape of the flexible catheter may become unavailable in the presence of mechanical vibrations. The mechanical vibrations may be caused, for example, by the insertion or removal of a tool (e.g., a visual probe, tool, needle, forceps, etc.). These tools may be more rigid than the flexible catheter and may excite some vibrations during insertion / retraction. The fault condition may be temporary. For example, the fault condition may disappear after or shortly after the tool insertion or retraction is complete. While an error on the sensor signal exists, the sensor signal may be inappropriate or unsuitable for use as a feedback signal for closed-loop control. Thus, when an anomaly exists, the control method may rely on an alternative feedback signal. In one or more embodiments, the alternative feedback signal is an estimate of the actual articulation motion. An estimate of the actual articulation may be generated by a model of the flexible catheter based on sensor signals representing the movement of the actuators that drive the articulation of the flexible catheter.

[0075] The flowchart of FIG. 7 illustrates an exemplary method (700) for controlling a flexible catheter, according to one or more embodiments. The method may be used to control articulation of a flexible catheter. The articulation may be along one or more degrees of freedom (e.g., pitch and / or yaw). A single segment (e.g., a terminal segment) of the flexible catheter, multiple segments, or the entire flexible catheter may be articulated. For example, the distal portion (518) of the flexible catheter (502) shown in FIG. 5A may be articulated. The method (700) may be executed iteratively to control the flexible catheter over time, for example, based on the cycle time of a control loop implemented to control the articulation of the flexible catheter.

[0076] In operation 702, an articulation sensor signal is obtained from an articulation sensor. The articulation sensor signal may represent articulation (e.g., shape) of at least a portion of the flexible catheter. As described above, the articulation sensor may be any type of sensor suitable for measuring articulation of a catheter. The articulation sensor may sense along single or multiple articulation degrees of freedom. The articulation sensor may sense articulation of one segment of the flexible catheter, multiple segments, or the entire flexible catheter. The sensor may be, for example, a shape sensor as described above. The articulation sensor signal may provide a value for the articulation, which may indicate the angle, position, orientation, speed, velocity, attitude, and / or shape of one or more portions of the flexible catheter. The articulation sensor signal may be accompanied by one or more flags to label the articulation sensor signal. For example, an articulation sensor signal may be labeled as unreliable if the tracking unit (e.g., as described with reference to FIG. 5A) concludes that the raw sensor signal obtained from the articulation sensor is unreliable (e.g., based on a buffer that holds only older raw articulation sensor signal values). If the raw sensor signal is deemed unreliable, the articulation sensor signal may not provide a value.

[0077] In operation 704, an actuator sensor signal is obtained from the actuator sensor. The actuator sensor signal may represent the movement (e.g., position or rotation) of an actuator used to drive articulation of the flexible catheter (e.g., by pulling or releasing tension on a pull wire). As described above, the actuator sensor may be any type of sensor suitable for measuring the movement of an actuator that drives articulation. The actuator sensor may be, for example, an encoder (e.g., an incremental encoder) on a motor shaft of a servo motor. If multiple actuators are used for articulation along one or more degrees of freedom, the articulation sensor signal may include signals obtained from multiple encoders. Configurations for driving articulation using one or more actuators were described with reference to FIG. 5A. The actuator sensor signal may provide one or more values ​​representing the state of the actuator, for example, the angle of the motor shaft. The actuator sensor signal may include position and / or velocity information.

[0078] Those skilled in the articulation sensor signal will appreciate that the actuator sensor signal may include position and / or velocity information. A velocity signal may be derived from a position signal via numerical differentiation. Similarly, a position signal may be derived from a velocity signal via numerical integration.

[0079] In operation 706, a test may be performed to determine whether there is an anomaly in the articulation sensor signal. The anomaly may be any change in the articulation sensor signal that prevents or prevents the articulation sensor signal from being used as a feedback signal to control the articulation of the flexible catheter. For example, the anomaly may be degradation (e.g., noise) in the articulation sensor signal caused by mechanical vibration. As described above, mechanical vibration may occur during insertion or removal of a tool into or from the flexible catheter. The test may be performed by evaluating a flag associated with the articulation sensor signal. If used to indicate mechanical vibration, the flag may be set after analyzing the articulation sensor signal, for example, for frequencies indicative of mechanical vibration. In the example flowchart of FIG. 7, an anomaly in the articulation sensor exists, and the process may proceed to operation 708.

[0080] Operations 708 and 710 may be performed in an actuator feedback control mode, in which the actuator sensor signal may be used as a feedback signal to control the articulation of the flexible catheter.

[0081] In operation 708, an articulation estimate is determined by applying a model of the flexible catheter to the actuator sensor signals. The model may be based on known characteristics (e.g., kinematic and / or dynamic) of the flexible catheter, allowing for the articulation estimate to be determined based on the actuator sensor signals by simulation when actual measurements of articulation by the articulation sensors are not available. The model used in operation 708 may be predetermined, as described below with reference to FIG. 8. An exemplary implementation of the model is described below with reference to FIG. 11.

[0082] In operation 710, the actuator(s) used to articulate the flexible catheter may be controlled based on the articulation motion estimate. A feedback controller used to control the actuator(s) may use the articulation motion estimate as a feedback signal and may also accept a command input. The feedback controller may be configured to minimize an error between the command input and the feedback signal (here, the articulation motion estimate) to drive the actuator(s). When the actuator(s) are driven, the articulation of the flexible catheter (driven by the actuator(s)) may follow the command input.

[0083] Acts 708 and 710 may be performed repeatedly, such as in the presence of anomalies, with each run determining an updated joint motion estimate (when performing act 708).

[0084] The flowchart in Figure 8 illustrates an exemplary method (800) for controlling a flexible catheter, according to one or more embodiments. For example, the method may be used to control articulation of a flexible catheter. The articulation may be along one or more articulation degrees of freedom. A single segment (e.g., a terminal segment), multiple segments, or the entire flexible catheter may be articulated. For example, a distal portion of the flexible catheter may be articulated.

[0085] In operation 802, an articulation sensor signal is obtained from an articulation sensor. The articulation sensor signal may represent articulation (e.g., shape) of at least a portion of the flexible catheter. As described above, the articulation sensor may be any type of sensor suitable for measuring articulation of a catheter. The articulation sensor may sense along single or multiple degrees of articulation freedom. The articulation sensor may sense articulation of one segment of the flexible catheter, multiple segments, or the entire flexible catheter. The sensor may be, for example, a shape sensor as described above. The articulation sensor signal may provide a value for articulation, which may indicate the angle, position, orientation, speed, velocity, attitude, and / or shape of one or more portions of the flexible catheter. In some embodiments, the articulation sensor signal may be low-pass filtered to smooth the articulation sensor signal. The low-pass filter may be a moving average filter. In addition to performing filtering, the moving average filter may also function as a buffer that stores a history of articulation sensor values. If the raw articulation sensor signal value is bad, it may not enter the buffer. Instead, the last known good raw articulation sensor signal value may be retained. Thus, the moving average filter may provide an articulation sensor signal even if one or a few raw articulation sensor signal values ​​are bad. When the buffer no longer holds valid raw articulation sensor signal values, the buffer may be considered depleted, and a flag may be set indicating that the articulation sensor signal is no longer valid. Thus, the articulation sensor signal may be accompanied by one or more flags to label the articulation sensor signal. For example, an articulation sensor signal may be labeled as unreliable if the tracking unit (e.g., as described with reference to FIG. 5A ) concludes that the raw sensor signal obtained from the articulation sensor is unreliable (e.g., based on a buffer holding old raw articulation sensor signal values). If the raw sensor signal is deemed unreliable, the articulation sensor signal may not provide a value.

[0086] In operation 804, an actuator sensor signal is obtained from the actuator sensor. The actuator sensor signal may represent the movement (e.g., position or rotation) of an actuator used to drive articulation of the flexible catheter (e.g., by pulling or releasing tension on a pull wire). As described above, the actuator sensor may be any type of sensor suitable for measuring the movement of an actuator that drives articulation. The actuator sensor may be, for example, an encoder (e.g., an incremental encoder) on the motor shaft of a servo motor. If multiple actuators are used for articulation along one or more degrees of freedom, the articulation sensor signal may include signals obtained from multiple encoders. Configurations for driving articulation using one or more actuators were described with reference to FIG. 5A. The actuator sensor signal may provide one or more values ​​representing the state of the actuator, for example, the angle of the motor shaft. The actuator sensor signal may include position and / or velocity information.

[0087] Those skilled in the articulation sensor signal will appreciate that the actuator sensor signal may include position and / or velocity information. A velocity signal may be derived from a position signal by numerical differentiation. Similarly, a position signal may be derived from a velocity signal by numerical integration.

[0088] In operation 806, a test may be performed to determine whether there is an anomaly in the articulation sensor signal. The anomaly may be any change in the articulation sensor signal that prevents or prevents the articulation sensor signal from being used as a feedback signal to control the articulation of the flexible catheter. For example, the anomaly may be degradation (e.g., noise) of the articulation sensor signal caused by mechanical vibration. As described above, mechanical vibration may occur during insertion or removal of a tool into or from the flexible catheter. The test may be performed by evaluating a flag associated with the articulation sensor signal. If the flag indicates that the articulation sensor signal is normal (e.g., uncompromised), the method may proceed to operation 808. If the flag indicates that the articulation sensor signal is anomalous (e.g., compromised, such as by mechanical vibration), the method may proceed to operation 816.

[0089] In operation 808, a test may be performed to determine whether the system is returning from actuator feedback control mode to articulation feedback control mode. The actuator feedback control mode may be used when the articulation sensor signal is unavailable as a feedback signal for controlling the articulation of the flexible catheter. The articulation feedback control mode may be used when the articulation sensor signal is available as a feedback signal for controlling the articulation of the flexible catheter. According to one or more embodiments, operation 808 may be performed to enable a transition to normal operation of the controlled system when the articulation sensor signal returns. The determination in operation 808 may be made, for example, by examining a flag indicating whether the system was previously operating in actuator feedback control mode. If the flag indicates that the system has returned from actuator feedback control mode (808:Y), one or more of the operations shown in the exemplary method of FIG. 9 may be performed. If the flag indicates that the system has not returned from actuator feedback (e.g., indicates continued operation in articulation feedback control mode), the method may proceed to operation 810.

[0090] Operations 810 and 812 may be performed in an articulation feedback control mode, in which the articulation sensor signal may be used as a feedback signal to control the articulation of the flexible catheter.

[0091] In operation 810, a joint motion estimate may be determined based on a model of the flexible catheter. For example, under normal operating conditions (e.g., when no abnormalities are detected), the joint motion estimate may be calculated at normal time intervals, for example, based on the cycle time of a control loop implemented to control the articulation of the flexible catheter. The joint motion estimate may be generated by a model operating on the actuator sensor signals. The model (e.g., a simulation model) may establish a mathematical relationship between the state of the actuator (e.g., rotational position and / or velocity) and the state of the flexible catheter in one or more joint degrees of freedom (e.g., joint motion that may be expressed as an angle and / or rate of change of joint motion that may be expressed as an angular velocity). Thus, the model may be used to predict the current state of the flexible catheter in one or more joint degrees of freedom based on the current state of the actuator, as represented by the actuator sensor signals. The state processed by the model may include position, velocity, and / or acceleration.

[0092] In operation 812, an error correction for the articulation estimate may be determined and / or the error correction may be applied to the articulation estimate. The error-corrected articulation estimate may correspond to (e.g., match) the actual articulation of the flexible catheter as measured by the articulation sensor. In some scenarios, the articulation estimate determined in operation 810 may be inaccurate because the simulation model does not always accurately reflect the mechanical configuration of the flexible catheter. The error correction may be determined based on a comparison of the articulation estimate and the actual articulation (e.g., shape) of the flexible catheter as represented by the articulation sensor signal. For example, the error correction may be determined by subtracting the articulation estimate from the actual articulation represented by the articulation sensor signal. To compensate for possible inaccuracies in the articulation estimate, the error correction may then be applied to the articulation estimate to achieve a result that more closely approximates the articulation sensor signal. Before applying the error correction to the articulation estimate, the error correction may be low-pass filtered. Low-pass filtering may facilitate smooth transitions between different control modes of the system, as shown in the performance data in Figure 12 below. After error correction, the joint motion estimate (e.g., determined in operation 810) may correspond to (e.g., match) the actual joint motion, as represented by the joint motion sensor signal. Operation 810 may be performed repeatedly in the absence of anomalies, so that the error-corrected joint motion estimate may track the actual joint motion over time.

[0093] An exemplary implementation of the simulation model and error correction is provided below with reference to Figure 11. Further, the construction of the identification and simulation model is described below with reference to Figure 10.

[0094] In operation 814, the actuator(s) used to articulate the flexible catheter may be controlled based on the articulation sensor signals. In one or more embodiments, a feedback controller (e.g., a servo controller) such as that first described with reference to FIG. 1 may be used to control the articulation. The feedback controller may rely on feedback from the articulation sensors and may accept command input. The command input may be provided by a user commanding the articulation and / or by an algorithm responsible for controlling the articulation of the flexible catheter. The command input may include a commanded articulation position and / or a commanded articulation velocity.

[0095] Returning to operation 806, if an anomaly is present in the articulation sensor signal (806:Y), the method may optionally proceed to operation 816. In operation 816, a test may be performed to determine whether additional requirements are met to allow the system to operate in actuator feedback control mode, as described below. The additional requirements may be, for example, that the flexible catheter be in a position-holding mode. In position-holding mode, joint motion may be held constant. User commands during position-holding mode may not articulate the flexible catheter. For example, the system may reject user commands during position-holding mode. The absence of motion in the joint motion degree(s) makes it more likely that the mapping from actuator motion to joint motion will remain constant, thus keeping the simulation model valid. Alternatively, the system may allow movement commands of limited amplitude and / or velocity during position-holding mode. If the additional requirement(s) are met (816:Y), the method may proceed by entering actuator feedback control mode. If the additional requirement(s) are not met (816:N), the method may proceed to operation 824 to switch the system to a limp catheter control mode, as described in more detail below.

[0096] One or more of operations 818, 820, or 822 may be performed in an actuator feedback control mode, in which an articulation sensor signal may not be available as a feedback signal for controlling articulation of the flexible catheter. A joint motion estimate generated based on a model of the flexible catheter may be used instead.

[0097] In operation 818, a joint motion estimate is determined by applying a model of the flexible catheter to the actuator sensor signals. The model used in operation 818 may be a model determined when operating in joint motion feedback control mode, as described above. In some examples, the model may include an error correction. For example, the error correction used in operation 818 may be the most recent error correction determined (e.g., by performing operation 812) before the anomaly appeared. An example of operation 818 is described below with reference to FIG. 11.

[0098] In operation 820, the actuator(s) used to articulate the flexible catheter may be controlled based on the articulation motion estimate. A feedback controller used to control the actuator(s) may use the articulation motion estimate as a feedback signal and may also accept a command input. The feedback controller may be configured to minimize an error between the command input and the feedback signal (here, the articulation motion estimate) to drive the actuator(s). When the actuator(s) are driven, the articulation of the flexible catheter (driven by the actuator(s)) may follow the command input.

[0099] Acts 818 and 820 may be performed repeatedly, such as in the presence of anomalies, with each run determining an updated joint motion estimate (when performing act 818).

[0100] In operation 822, a test is performed to determine whether a time limit has been exceeded. The time limit may govern the amount of time the system operates in the actuator feedback control mode. Over time, if actual feedback from the joint motion sensor is not available to error-correct the joint motion estimate, the joint motion estimate may become increasingly inaccurate. The time limit may be specified so that the system may continue to operate in the actuator feedback control mode for a limited amount of time. The time limit may include a predetermined time limit. The time limit may be set based on the mechanical characteristics of the flexible catheter, the control algorithm being used, etc. These factors may affect how rapidly the flexible catheter diverges from the estimated joint motion. Furthermore, the conditions of use may also influence the selection of the time limit. In a completely stationary environment, the flexible catheter is unlikely to diverge from the estimated joint motion, but in a moving environment, deviations may occur relatively quickly. The time limit may be selected to minimize the possibility of instability and / or undesired motion. For example, the time limit may be set so that errors that may occur during the time limit are deemed acceptable. If the time limit (822:N) has not been exceeded, the method may proceed to operation 802, as described above. If the time limit (822:Y) has been exceeded, the method may proceed to operation 824.

[0101] In operation 824, the system may be switched to operate in a limp catheter control mode. In the limp catheter control mode, the flexible catheter may be relaxed along the articulation degree(s). When entering the limp catheter control mode, the actuator(s) may be controlled to gradually decrease tension on the pull wires used to articulate the catheter along the articulation degree(s). A certain minimum tension may be maintained. In the limp catheter control mode, the flexible catheter may be backdriveable along the articulation degree(s). When the flexible catheter is backdriveable, an external force acting on the flexible catheter may cause articulation. A relatively small force may be sufficient to cause backdrive.

[0102] In method 800, the system may temporarily operate in the actuator feedback control mode, such as when vibrations caused by the insertion of an instrument into the flexible catheter temporarily corrupt the articulation sensor signal. Operation in the actuator feedback control mode may be time-limited, but the available time may be sufficient to bridge the period between when the articulation sensor signal is unavailable and when the articulation sensor signal becomes available. After the articulation sensor signal becomes available (e.g., is no longer corrupted), the system may revert to operating in the articulation feedback control mode. Further aspects of the transition between the articulation feedback control mode and the actuator feedback control mode are described below with reference to the exemplary implementation shown in FIG. 10.

[0103] The flowchart of FIG. 9 illustrates an exemplary method (900) for controlling a flexible catheter, according to one or more embodiments. The method may be used to control articulation of the flexible catheter during a transition from an actuator feedback control mode to an articulation feedback control mode. As previously described, one or more of the operations shown in FIG. 9 may be performed after the system determines to return from the actuator feedback control mode to the articulation feedback control mode (e.g., as determined in operation 808 of FIG. 8 ). The exemplary method (900) may be used for smooth transitions between modes and when the joint motion estimate deviates from the actual joint as reflected by the articulation sensor signal. A hard switch may result in undesired abrupt movements of the flexible catheter, which may be avoided by a smooth transition.

[0104] In operation 902, a gradual transition from an actuator feedback control mode to an articulation feedback control mode is performed. In this hybrid operation mode, both the articulation feedback control mode and the actuator feedback control mode are active. To control the actuator, a step interpolation between controlling the actuator based on the articulation sensor signal (e.g., as described in operation 814) and controlling the actuator based on the articulation estimate (e.g., as described in operation 820) may be performed. Initially, the control may be substantially based on the articulation estimate (e.g., based entirely on the articulation estimate). Over multiple iterations of performing operation 902 resulting from repeated execution of method 900, the control may be increasingly based on the articulation sensor signal, for example, until the control is substantially based on the articulation sensor signal (e.g., based entirely on the articulation sensor signal). The rate at which the transition occurs may be configurable.

[0105] Execution of operation 902 is optional. Even if operation 902 is not executed, the system can perform a gradual transition from the actuator feedback control mode to the joint motion feedback control mode. As described above, the error correction (e.g., as determined in operation 812) is assumed to be low-pass filtered. When updating the joint motion estimate, the joint motion estimate is governed by the time constant of the low-pass filter and gradually approaches the joint motion sensor signal. Thus, the joint motion estimate can be used to control the actuator until the joint motion estimate converges to the joint motion sensor signal. By then, the control can switch to using the joint motion sensor signal directly, achieving a smooth transition.

[0106] When using a transition scheme such as that described in operation 902, additional control over the transition from actuator feedback control mode to joint motion feedback control mode may be available, e.g., the subsequent progression may no longer be governed by the time constant of a low pass filter. As will be explained briefly below, other methods for transitioning between predictive and sensor-based signals may be used, e.g., a Kalman filter.

[0107] In operation 904, a test is performed to determine whether convergence of the joint motion estimate to the joint motion sensor signal is reached. If convergence is not reached, operation 902 may be repeated with the next execution of method (900). If convergence is reached, the method may proceed to operation 906.

[0108] In act 906, after convergence of the joint motion estimate to the articulation sensor signal, an error correction may be set so that the joint motion estimate corresponds to (e.g., matches) the articulation sensor signal. Act 906 may be useful if the transition performed in act 902 proceeds at a rate faster than the time constant of the low pass filter allows. In this case, act 904 may be used to set the error correction rather than waiting for its gradual convergence to ensure that the error correction is accurate and allow for immediate switching back to actuator feedback control mode if necessary.

[0109] The gradual transition may be terminated at operation 908. Thus, upon reaching operation 908, during the next execution of operation 808 of method (800), the system may switch (808:N) to operate in the joint motion feedback control mode.

[0110] The flowchart of Figure 10 illustrates an exemplary method for performing system identification for setting up a simulation model. This method may be performed prior to performing the methods of Figures 7, 8, and 9. This method may be performed as part of initialization, calibration, or recalibration of the system and / or flexible catheter.

[0111] In operation 1002, system identification is performed. System identification may include determining a relationship between movement by the actuator(s) as measured by the actuator sensor(s) and the resulting articulation movement by the flexible catheter as measured by the articulation sensor. System identification may be performed under known operating conditions. For example, a particular pattern of calibration movement may be commanded to the actuator. System identification may be part of a catheter test sequence that may be performed during or after manufacture or assembly of the system and / or flexible catheter, upon system startup, after installation of the flexible catheter on the system, and / or prior to insertion of the flexible catheter into a patient, etc. Examples of catheter calibration and test sequences are provided in PCT Patent Application No. PCT / US2019 / 053928 (published as WO2020 / 072398, which is a priority claim to U.S. Patent Application No. 62 / 741,242, filed October 4, 2018, entitled "Systems and Methods for Device Verification and Sensor Calibration"), the entire contents of which are incorporated herein by reference.

[0112] The simulation model described herein uses matrices (e.g., coupling matrices) that establish the relationship between actuator angles and joint motion angles. The coupling matrix may include a gain (gain matrix). The gains of the coupling matrix may establish how a particular actuator angle affects a particular joint angle. For example, consider a flexible catheter with pitch and yaw joint degrees of freedom. Further, assume that two pairs of antagonistically acting actuators drive the flexible catheter with pitch and yaw joint degrees of freedom. Therefore, the coupling matrix may include a total of eight gains to couple the actuator motion to the joint motion. The magnitude of the gains may depend on the mechanical design of the flexible catheter. For example, the gains for pitch and yaw degrees may be orthogonal. As another example, the gains may be isotropic for the pitch and yaw degrees of freedom. Alternatively, the gains may be anisotropic, such as when the pitch and yaw degrees of freedom are not mechanically symmetric. Furthermore, there may be cross-coupling between the pitch and yaw degrees of freedom. These factors are represented by the coupling matrix as obtained during system identification. The coupling matrix may be static, eg, the gains may be held constant after system identification is completed.

[0113] Other simulation models, which may be more complex, may be used without departing from this disclosure, for example, models that take into account system dynamics including compliance and friction may be used.

[0114] 11 illustrates an example implementation according to one or more embodiments. In this example, the position q of the flexible catheter along the articulation degree of freedom fbs (1102), and the position q of the drive actuator enc (1104) is shown as the input. fbs (1102) may be obtained from a joint motion sensor (e.g., a fiber optic shape sensor) and may be low-pass filtered (e.g., using a moving average filter). enc (1104) can be obtained from a position sensor (e.g., an encoder) of an actuator that drives the flexible catheter along the joint degree of freedom. fbs(1102) and q enc To be able to directly compare (1104), q enc Assume that (1104) is processed by a simulation model (e.g., multiplied by an appropriate gain). fbs (1102) to q enc By subtracting (1104), the error q err (1106) can be obtained. The low pass filter (LPF) operation (1112) is err (1106). If no abnormality is detected (e.g., q fbs (1102) good), the system can be in the joint motion feedback control mode previously described in FIG. 8. If the joint motion estimate (1108) is enc (1104) (which may be low-pass filtered and passed through switch (1114)) q err Furthermore, q fbs (1102) can be used as the output (1110) for feedback control of joint motion. fbs If there is a fault (1102), the system can go into actuator feedback control mode as previously described in Figure 8. The joint motion estimate (1108) is calculated based on the last successfully obtained q err (Switch (1114) is the last successfully acquired q err (in the open position to hold the enc9 , the output (1110) can be obtained by adding (1104) to (1108). (1108) can be used as the output (1110) for feedback control of the joint motion. Switching from the joint motion feedback control mode to the actuator feedback control mode (e.g., when an abnormality in the joint motion sensor is detected) can be instantaneous in some examples. In contrast, switching from the actuator feedback control mode to the joint motion feedback control mode (e.g., after recovery from the abnormality) can be incremental in some examples, as described in FIG. 9 . Therefore, when switching from the actuator feedback control mode to the joint motion feedback control mode, (1110) can be obtained by adding (1108) and q fbs This behavior is shown in Figure 12.

[0115] In the implementation of Figure 11, similar operations can be performed in the velocity domain, which can be performed in addition to operations in the position domain if the control algorithm, e.g., a proportional-derivative (PD) controller for driving the actuator, uses both position and velocity information. TIFF2025137578000002.tif914(1122) and TIFF2025137578000003.tif1014(1124) is q fbs (1102) and q enc It can be obtained from (1104) by numerical differentiation (1140). TIFF2025137578000004.tif913(1126) From TIFF2025137578000005.tif914(1122) The low-pass filter (LPF) operation (1132) can be performed by subtracting TIFF2025137578000006.tif1014 (1124). TIFF2025137578000007.tif913(1126) can be executed if no abnormality is detected (e.g., q fbs (1102) is good), the system can be in the joint motion feedback control mode previously described in FIG. TIFF2025137578000008.tif1013(1128) TIFF2025137578000009.tif1014(1124) TIFF2025137578000010.tif913 (which may be low-pass filtered (1132) and passed through switch (1134)). TIFF2025137578000011.tif914(1122) is the output for feedback control of joint movement. TIFF2025137578000012.tif1019(1130). If an anomaly exists (e.g., TIFF2025137578000013.tif914(1122) is bad), the system can be in the actuator feedback control mode previously described in Figure 8. Joint motion estimates TIFF2025137578000014.tif1013(1128) This can be obtained by setting TIFF2025137578000015.tif1017 to zero (switch 1134 connects to the zero input). TIFF2025137578000016.tif1013(1108) is the output for feedback control of joint movement. It can be used as TIFF2025137578000017.tif1019(1110).

[0116] In the implementation example in Figure 11, q err may be continuously calculated when in joint motion feedback control mode, allowing for smooth transition to / from actuator feedback control mode. For example, q fbs and q encIf the relationship between err , q fbs and q enc Despite the changing relationship between TIFF2025137578000018.tif914 is q fbs For example, if a segment of a flexible catheter proximal to an articulation site changes its shape (e.g., due to catheter bending), q fbs and q enc In this case, the lengths of the pull wires from the various actuators may be changed, thereby changing the relationship between q fbs and q enc Also, changes in catheter stiffness can change the relationship as a result of small changes in catheter length associated with changes in stiffness.

[0117] As an alternative to the implementation shown in Figure 11, a nonlinear state estimator can be used to estimate catheter articulation. For example, a Kalman filter (e.g., an extended Kalman filter) that accounts for the full system dynamics (e.g., including friction, inertia, and / or compliance) and sensor noise characteristics, as well as nonlinearities resulting from quantization and sampling effects, can be used to provide more accurate estimates of articulation state, including individual pullwire tension and actual articulation angle. An extended Kalman filter implementation can replace the embodiment shown in Figure 11, and the Kalman filter gain can adjust for a smooth transition between using the articulation sensor signal and using the articulation estimate without requiring a dedicated switching instance.

[0118] FIG. 12 shows plots 1200, 1250 illustrating the performance of an implementation such as that described in FIG. 11 when a flexible catheter is manipulated under realistic conditions. Plot 1200 in the upper panel illustrates various variables related to catheter movement, while plot 1250 in the lower panel illustrates the number of cycles of invalid articulation sensor signals following a valid articulation sensor signal. Plots 1200, 1250 are aligned in time. Looking at plot 1250 in the lower panel, two long time intervals with invalid articulation sensor signals 1252, 1254 are shown. The two time intervals are shown interrupted by a very brief moment 1256 with valid articulation sensor data. Additional time intervals with valid articulation sensor signals 1258, 1260 are shown before and after time intervals 1252, 1254. The invalid sensor signals may be the result of vibration, as previously discussed. Looking at the plot in the upper panel (1200), the joint motion sensor signal q fbs is plotted using a black dotted line. Points of time where a valid articulation sensor signal was not collected are indicated using an "x" or "o" symbol. A combination of "x" and "o" symbols represents a cycle with an invalid articulation sensor signal, as plotted in the lower panel plot (1250). An invalid articulation sensor signal, plotted using an "x" symbol, is distinguished from an invalid articulation sensor signal, plotted using an "o" symbol. Specifically, although a valid sample was not obtained at the point in time indicated using the "o" symbol, a buffer configured to store a history of articulation sensor signal values ​​may be used to provide the value of the articulation sensor signal. Thus, at any point in time where the "o" symbol indicates a missing sample, the controller may continue to operate normally based on the buffered articulation sensor signal. Once the buffer is depleted (e.g., indicated using an "x" symbol), the controller may switch to operating in actuator feedback control mode.

[0119] In the example shown in the upper panel plot (1200), the command input may be a command position that is always held at 80° (grey dashed line, 1202). The solid line (1204) is the output of the algorithm used for feedback control of the joint motion. TIFF2025137578000019.tif1415. The black dashed line (1206) represents the estimated joint motion. TIFF2025137578000020.tif914. The black dotted line (1208) represents the articulation sensor signal. If the articulation sensor signal is not available (e.g., an "x" symbol), the system may be in actuator feedback control mode. Therefore, the signal used for feedback to the controller TIFF2025137578000021.tif1415 is the joint motion estimate. TIFF2025137578000022.tif914. Additionally, if a joint motion sensor signal is available, the signal may be used for feedback to the controller. TIFF2025137578000023.tif1415 is the joint movement sensor signal q fbs As explained above, the switch from the actuator feedback control mode to the joint motion feedback control mode may occur during a transition period. During the transition period, the signal used for feedback to the controller may be TIFF2025137578000024.tif1415 is a smooth joint movement sensor signal q fbs After convergence is reached, the joint motion estimates TIFF2025137578000025.tif914 is a graph showing the joint motion sensor signal q as described above with reference to FIG. fbs can be set to match (e.g., in one step).

[0120] While the present invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate that other embodiments may be devised without departing from the scope of the invention disclosed herein. Accordingly, the scope of the present invention should be limited only by the claims.

[0121] The following additional note is added: (Supplementary Note 1) A flexible catheter configured to articulate along a degree of freedom; an actuator disposed at a proximal portion of the flexible catheter, the actuator configured to actuate the flexible catheter along the degree of freedom; an articulation sensor configured to provide an articulation sensor signal representative of articulation of the flexible catheter; an actuator sensor configured to provide an actuator sensor signal representative of movement of the actuator; a controller coupled to the actuator, based on detecting an anomaly in the first articulation sensor signal: determining an articulation estimate of the flexible catheter based on a model of the flexible catheter applied to a first actuator sensor signal; controlling the actuator based on the joint motion estimate; a controller configured to: having Computer-assisted medical systems. (Supplementary Note 2) The controller detects no abnormality based on the following: determining a second articulation motion estimate of the flexible catheter based on the model of the flexible catheter applied to a second actuator sensor signal; determining an error correction based on a difference between the second articulation estimate and an actual articulation of the flexible catheter, the actual articulation being based on a second articulation sensor signal; controlling the actuator based on the second articulation sensor signal; further configured as follows: 10. The computer-assisted medical system of claim 1. (Supplementary Note 3) The determining of the second joint motion estimate includes adjusting the second joint motion estimate based on the error correction. 10. The computer-assisted medical system of claim 2. (Supplementary Note 4) The controller is further configured to apply a low-pass filter to the error correction. 10. The computer-assisted medical system of claim 2. (Supplementary Note 5) The controller is further configured to determine whether a requirement is met before determining the joint motion estimate. 10. The computer-assisted medical system of claim 1. (Supplementary Note 6) Determining whether the requirements are met includes determining that the computer-assisted medical system is in a position-keeping mode. 6. The computer-assisted medical system of claim 5. (Supplementary Note 7) The controller is further configured to relax the flexible catheter along the degree of freedom if the requirement is not met. 6. The computer-assisted medical system of claim 5. (Supplementary Note 8) The controller is further configured to control the actuator based on a second articulation sensor signal based on detecting disappearance of the abnormality. 10. The computer-assisted medical system of claim 1. (Supplementary Note 9) The controller: Step interpolation; or Kalman filter; performing a gradual transition from controlling the actuator based on the articulation estimate to controlling the actuator based on the second articulation sensor signal based on one or more of: 9. The computer-assisted medical system of claim 8. (Supplementary Note 10) The controller is configured to: determine, after the gradual transition is completed, a second articulation estimate corresponding to an actual articulation of the flexible catheter based on an error correction used to correct the articulation estimate. 10. The computer-assisted medical system of claim 9. (Supplementary Note 11) The model shows a relationship between a movement of the actuator and the articulation of the flexible catheter caused by the movement of the actuator. 11. A computer-assisted medical system according to any one of claims 1 to 10. (Supplementary Note 12) The relationship includes a gain. 12. The computer-assisted medical system of claim 11. (Supplementary Note 13) The articulation of the flexible catheter includes bending of a distal portion of the flexible catheter. 11. A computer-assisted medical system according to any one of claims 1 to 10. (Supplementary Note 14) The controller: further configured to process the articulation sensor signal in a buffer configured to store a history of articulation sensor signal values; The anomaly is detected when the buffer is exhausted. 11. A computer-assisted medical system according to any one of claims 1 to 10. (Supplementary Note 15) The buffer operates as a moving average filter. 15. The computer-assisted medical system of claim 14. (Supplementary Note 16) The buffer is configured to hold a last known good articulation sensor signal value. 15. The computer-assisted medical system of claim 14. (Supplementary Note 17) The joint motion estimate includes one or more of a position or a velocity. 11. A computer-assisted medical system according to any one of claims 1 to 10. (Supplementary Note 18) The flexible catheter has a lumen configured to receive a tool. 11. A computer-assisted medical system according to any one of claims 1 to 10. (Supplementary Note 19) The abnormality includes a degraded joint motion sensor signal. 11. A computer-assisted medical system according to any one of claims 1 to 10. (Supplementary Note 20) The actuator sensor includes an encoder. 11. A computer-assisted medical system according to any one of claims 1 to 10. (Supplementary Note 21) The articulation motion sensor includes a fiber optic shape sensor. 11. A computer-assisted medical system according to any one of claims 1 to 10. (Supplementary Note 22) The joint motion sensor includes an electromagnetic sensor. 11. A computer-assisted medical system according to any one of claims 1 to 10. (Supplementary Note 23) A non-transitory machine-readable medium containing machine-readable instructions that, when executed by one or more processors associated with a medical system, cause the medical system to: acquiring an articulation sensor signal from an articulation sensor, the articulation sensor signal representing articulation of the flexible catheter; acquiring an actuator sensor signal from an actuator sensor, the actuator sensor signal representing movement of an actuator configured to drive articulation of the flexible catheter; Based on detecting an abnormality in the first articulation sensor signal: determining a joint motion estimate based on a model of the flexible catheter applied to a first actuator sensor signal; controlling the actuator based on the joint motion estimate; Non-transitory machine-readable medium. (Supplementary Note 24) The machine-readable instructions further cause the medical system, based on not detecting an anomaly: determining a second articulation estimate of the flexible catheter based on the model of the flexible catheter applied to a second actuator sensor signal; determining an error correction based on a difference between the second articulation estimate and an actual articulation of the flexible catheter, the actual articulation being based on a second articulation sensor signal; controlling the actuator based on the second articulation sensor signal; 24. The non-transitory machine-readable medium of claim 23. (Supplementary Note 25) The determining of the second joint motion estimate includes adjusting the second joint motion estimate based on the error correction. 25. The non-transitory machine-readable medium of claim 24. (Supplementary Note 26) The machine-readable instructions further cause the medical system to control the actuator based on a second articulation sensor signal upon detecting disappearance of the abnormality. 24. The non-transitory machine-readable medium of claim 23. (Supplementary Note 27) The machine-readable instructions further cause the medical system to: Step interpolation; or Kalman filter; performing a gradual transition from controlling the actuator based on the articulation estimate to controlling the actuator based on the second articulation sensor signal based on one or more of: 27. The non-transitory machine-readable medium of claim 26. (Supplementary Note 28) The machine-readable instructions further cause the medical system to: determine, after the gradual transition is completed, a second articulation estimate corresponding to an actual articulation of the flexible catheter based on an error correction used to correct the articulation estimate. 28. The non-transitory machine-readable medium of claim 27. (Supplementary Note 29) A method of operating a medical system, comprising: acquiring an articulation sensor signal from an articulation sensor, the articulation sensor signal representing articulation of the flexible elongate device; acquiring an actuator sensor signal from an actuator sensor, the actuator sensor signal representing movement of an actuator configured to drive articulation of the flexible elongate device; Based on detecting an anomaly in the first articulation sensor signal: Switching to an actuator feedback control mode, determining a joint motion estimate based on a model of the flexible elongate device applied to a first actuator sensor signal; and controlling the actuator based on the joint motion estimate; including the steps and; method. (Appendix 30) Based on not detecting anomalies: determining a second articulation estimate of the flexible elongate device based on the model of the flexible elongate device applied to a second actuator sensor signal; determining an error correction based on a difference between the second articulation estimate and an actual articulation of the flexible elongate device, the actual articulation being based on a second articulation sensor signal; controlling the actuator based on the second articulation sensor signal; 29. The method described in Appendix 29.

Claims

1. a flexible catheter configured to articulate along a degree of freedom; an actuator disposed in a proximal portion of the flexible catheter, the actuator configured to actuate the flexible catheter along the degree of freedom; an articulation sensor configured to provide an articulation sensor signal representative of articulation of the flexible catheter; an actuator sensor configured to provide an actuator sensor signal representative of movement of the actuator; a controller coupled to the actuator, based on the controller determining that an anomaly exists in the first articulation sensor signal that prevents or prevents the first articulation sensor signal from being used as a feedback signal to control the actuator: using the articulation sensor signal to control the actuator; determining an articulation estimate of the flexible catheter based on a model of the flexible catheter applied to a first actuator sensor signal; and controlling the actuator based on the joint motion estimate; a controller configured to temporarily switch to having Computer-assisted medical systems.

2. Based on the determination that the anomaly does not exist, the controller: determining a second articulation estimate of the flexible catheter based on the model of the flexible catheter applied to a second actuator sensor signal; determining an error correction based on a difference between the second articulation estimate and an actual articulation of the flexible catheter, the actual articulation being based on a second articulation sensor signal; controlling the actuator based on the second articulation sensor signal; further configured as follows: The computer-assisted medical system of claim 1 .

3. Based on the determination that the anomaly does not exist, the controller: correcting the second joint motion estimate using the error correction; further configured as follows: The computer-assisted medical system of claim 2 .

4. the controller is further configured to apply a low pass filter to the error correction. The computer-assisted medical system of claim 2 .

5. The controller is further configured to determine whether a requirement is met before determining the joint motion estimate. The computer-assisted medical system of claim 1 .

6. The controller is further configured to determine that the requirement is met when the computer-assisted medical system is in a position-keeping mode. The computer-assisted medical system of claim 5.

7. the controller is further configured to relax the flexible catheter along the degree of freedom when the computer-assisted medical system is not in the position-holding mode. The computer-assisted medical system of claim 6.

8. the controller is further configured to control the actuator based on a second articulation sensor signal based on detecting disappearance of the abnormality. The computer-assisted medical system of claim 1 .

9. The controller: and performing a gradual transition from controlling the actuator based on the articulation estimate to controlling the actuator based on the second articulation sensor signal based on a step interpolation. The computer-assisted medical system of claim 8.

10. The controller is configured to: determine a second articulation estimate corresponding to an actual articulation of the flexible catheter after completion of the gradual transition; The computer-assisted medical system of claim 9.

11. the model reflects an identified relationship between the movement of the actuator and the articulation of the flexible catheter caused by the movement of the actuator. A computer-assisted medical system according to any one of claims 1 to 10.

12. The relationship includes a gain. The computer-assisted medical system of claim 11.

13. The controller: further configured to process the articulation sensor signal in a buffer configured to store a history of articulation sensor signal values; The anomaly is detected when the buffer is exhausted. A computer-assisted medical system according to any one of claims 1 to 10.

14. the buffer being provided by a moving average filter; The computer-assisted medical system of claim 13.

15. if the articulation sensor signal value received from the articulation sensor is bad, the bad articulation sensor signal value is not entered into the buffer; The computer-assisted medical system of claim 13.

16. 1. A method of operating a medical system having a controller, comprising: the controller obtaining an articulation sensor signal from an articulation sensor, the articulation sensor signal representing articulation of the flexible catheter along a degree of freedom; the controller acquiring an actuator sensor signal from an actuator sensor, the actuator sensor signal representing movement of an actuator disposed in a proximal portion of the flexible catheter and configured to actuate the flexible catheter along the degree of freedom; Based on the controller determining that an anomaly exists in the first articulation sensor signal that prevents or prevents the first articulation sensor signal from being used as a feedback signal to control the actuator: using the articulation sensor signal to control the actuator; determining an articulation estimate of the flexible catheter based on a model of the flexible catheter applied to a first actuator sensor signal; and controlling the actuator based on the joint motion estimate; and temporarily switching to How it works.

17. the controller further processing the articulation sensor signal in a buffer configured to store a history of articulation sensor signal values; The anomaly is detected when the buffer is exhausted.

17. The method of claim 16.

18. the buffer being provided by a moving average filter; 18. The method of claim 17.

19. if the articulation sensor signal value received from the articulation sensor is bad, the bad articulation sensor signal value is not entered into the buffer; 18. The method of claim 17.

20. 1. A non-transitory machine-readable medium containing machine-readable instructions that, when executed by one or more processors of a controller associated with a medical system, cause the medical system to: acquiring an articulation sensor signal from an articulation sensor, the articulation sensor signal representing articulation of the flexible catheter along a degree of freedom; acquiring an actuator sensor signal from an actuator sensor, the actuator sensor signal representing movement of an actuator disposed at a proximal portion of the flexible catheter and configured to actuate the flexible catheter along the degree of freedom; Based on determining that an anomaly exists in the first articulation sensor signal that prevents or prevents the first articulation sensor signal from being used as a feedback signal to control the actuator: using the articulation sensor signal to control the actuator; determining an articulation estimate of the flexible catheter based on a model of the flexible catheter applied to a first actuator sensor signal; and controlling the actuator based on the joint motion estimate; Temporarily switch to Non-transitory machine-readable medium.

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