Struggling motion recognition and detection of flexible elongate devices

Abstract

A medical system includes a manipulator assembly and a control system. The manipulator assembly includes an actuator that controls an engaged state of the flexible elongate device by varying a tension applied to a pull wire of the flexible elongate device. The control system controls the actuator to change the engagement state of the flexible elongate device using a control scheme that defines an upper limit tension applied to each of the pull wires. The control system also determines that a commanded engaged state of the flexible elongate device cannot be achieved by controlling the first actuator if the first actuator does not apply more than an upper limit tension to the first pull wire. The control system also controls the second actuator to vary the amount of tension applied to the second pull wire if the first actuator does not apply more than an upper limit tension to the first pull wire to achieve a commanded engaged state.

Description

Technical Field

[0001] The disclosed embodiments relate to improved robotic and / or medical (including surgical) devices, systems, and methods. Background Technology

[0002] Minimally invasive medical techniques aim to reduce the amount of tissue damaged during medical procedures, thereby reducing patient recovery time, discomfort, and harmful side effects. Such techniques can be performed through natural openings in the patient's anatomy or through one or more surgical incisions. Through these natural openings or incisions, physicians can insert minimally invasive medical instruments (including surgical, diagnostic, therapeutic, and / or biopsy instruments) to reach target tissue locations. One such technique utilizes flexible and / or steerable elongated devices (such as flexible catheters or bronchoscopes) that can be inserted into the anatomical passage and navigated toward regions of interest within the patient's anatomy.

[0003] However, various elongation devices may encounter difficulties when reaching the desired region of interest. For example, the articulation of flexible elongation devices may be hindered by friction. When the friction becomes too severe, the desired articulation may become impossible for the elongation device. Summary of the Invention

[0004] The following is a brief overview of the various examples described herein and is not intended to identify key or important elements or to depict the scope of the claims.

[0005] In some examples, embodiments of this disclosure relate to a medical system comprising: a manipulator assembly including a plurality of actuators configured to control an engagement state of a flexible elongation device based on changing a plurality of tensions applied to a plurality of pullwires of the flexible elongation device; and a control system coupled to the manipulator assembly, the control system being configured to: control the plurality of actuators using a control scheme to change the engagement state of the flexible elongation device, the control scheme defining an upper limit tension applied to each of the plurality of pullwires; determine that a commanded engagement state of the flexible elongation device cannot be achieved by controlling a first actuator if the first actuator does not apply an upper limit tension to the first pullwire of the plurality of pullwires; and control a second actuator among the plurality of actuators to change the amount of tension applied to the second pullwire of the plurality of pullwires, thereby achieving a commanded engagement state, if the first actuator does not apply an upper limit tension to the first pullwire.

[0006] In some examples, embodiments of this disclosure relate to a non-transitory machine-readable medium comprising a plurality of machine-readable instructions executed by one or more processors associated with a medical system, the medical system including a manipulator assembly comprising a plurality of actuators configured to control an engagement state of a flexible elongation device based on changing a plurality of tensions applied to a plurality of traction lines of the flexible elongation device, the plurality of machine-readable instructions causing one or more processors to perform a method comprising: controlling the plurality of actuators to change the engagement state of the flexible elongation device using a control scheme defining an upper limit tension applied to each of the plurality of traction lines; determining that a commanded engagement state of the flexible elongation device cannot be achieved by controlling a first actuator if the first actuator does not apply an upper limit tension to the first traction line of the plurality of traction lines; and controlling a second actuator of the plurality of actuators to change the amount of tension applied to the second traction line of the plurality of traction lines, thereby achieving the commanded engagement state, if the first actuator does not apply an upper limit tension to the first traction line.

[0007] In some examples, embodiments of this disclosure relate to a method for operating a medical system including a manipulator assembly comprising a plurality of actuators configured to control an engagement state of a flexible elongation device based on changing a plurality of tensions applied to a plurality of traction lines of the flexible elongation device. The method includes: controlling the plurality of actuators using a control scheme to change the engagement state of the flexible elongation device, the control scheme defining an upper limit tension applied to each of the plurality of traction lines; determining that a commanded engagement state of the flexible elongation device cannot be achieved by controlling a first actuator if the first actuator does not apply an upper limit tension to the first traction line of the plurality of traction lines; and controlling a second actuator among the plurality of actuators to change the amount of tension applied to the second traction line of the plurality of traction lines, thereby achieving the commanded engagement state, if the first actuator does not apply an upper limit tension to the first traction line.

[0008] It should be understood that both the foregoing general description and the following detailed description are exemplary and illustrative in nature and are intended to provide an understanding of this disclosure without limiting its scope. In this regard, additional aspects, features, and advantages of this disclosure will be apparent to those skilled in the art from the following detailed description. Attached Figure Description

[0009] Figure 1 This is a simplified diagram of a medical system based on some implementation methods.

[0010] Figure 2AThis is a simplified diagram of a medical device system according to some implementation methods.

[0011] Figure 2B This is a simplified diagram of a medical device including a medical tool within an elongation device, according to some embodiments.

[0012] Figure 3A and Figure 3B This is a simplified side view of a medical device mounted on an insertion assembly in patient coordinate space, according to some embodiments.

[0013] Figure 4 This is a flowchart of a method according to some implementation methods.

[0014] Figure 5A This is an illustration of a scenario where the actual engagement state of the flexible elongation device differs from the commanded engagement state.

[0015] Figure 5B This is a diagram illustrating the actual engagement state and the commanded engagement state of the flexible elongation device according to some embodiments.

[0016] Figure 5C and Figure 5D It is a diagram of direct and indirect engagement trajectories based on detected friction, according to some implementation methods.

[0017] Figure 5E and Figure 5F It is a diagram of direct and indirect engagement trajectories based on detected friction, according to some implementation methods.

[0018] Figure 5G This is a diagram illustrating the torque or force limitation of an actuator according to some implementation methods.

[0019] The embodiments and advantages of this disclosure can be better understood by referring to the following detailed description. It should be understood that the same reference numerals are used to identify the same elements shown in one or more of the accompanying drawings, which are shown for illustrative purposes only and not for limiting the embodiments of this disclosure. Detailed Implementation

[0020] In the following description, specific details of some embodiments consistent with this disclosure are set forth. Numerous specific details are set forth to provide a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that some embodiments may be practiced without some or all of these specific details. The specific embodiments disclosed herein are intended to be exemplary and not restrictive. Other elements within the scope and spirit of this disclosure can be implemented by those skilled in the art, although not specifically described herein. Furthermore, to avoid unnecessary repetition, one or more features shown and described in association with one embodiment may be incorporated into other embodiments unless otherwise specifically described or if one or more features would render the embodiment inoperable. In some cases, well-known methods, processes, components, and circuits have not been described in detail to avoid unnecessarily obscuring aspects of the embodiments.

[0021] This disclosure describes various instruments and parts thereof based on their state in three-dimensional space. As used herein, the term “position” refers to the location of an object or part of an object in three-dimensional space (e.g., three translational degrees of freedom along Cartesian x, y, and z coordinates). As used herein, the term “orientation” refers to the rotational placement of an object or part of an object (e.g., one or more rotational degrees of freedom, such as roll, pitch, and yaw). As used herein, the term “pose” refers to the position of an object or part of an object in at least one translational degree of freedom and the orientation of the object or part of an object in at least one rotational degree of freedom (e.g., up to six total degrees of freedom). As used herein, the term “shape” refers to a set of poses, positions, and / or orientations measured along an object. As used herein, the term “distal” refers to a location closer to the surgical site, and the term “proximal” refers to a location further away from the surgical site. Thus, when an instrument is designed to perform surgery, the distal portion or distal end of the instrument is closer to the surgical site than the proximal portion or proximal end of the instrument.

[0022] Embodiments of this disclosure include medical systems and methods for operating such medical systems. Medical systems (e.g., medical systems using flexible elongation devices (e.g., catheters or endoscopes)) may include medical instruments that can be driven along one or more engagement degrees of freedom.

[0023] Driven along the engagement degree of freedom, this can involve engagement of the engageable body portion of the flexible elongation device (e.g., the distal portion of the flexible elongation device). In one example, the engagement degree of freedom includes engagement across the pitch and yaw axes. Driven along the engagement degree of freedom, this can be performed to navigate the distal end of the flexible elongation device toward target tissue and / or orient the end effector toward target tissue, thereby performing medical procedures such as biopsy, ablation, electroporation, etc. Engagement of the engageable body portion can be driven from the proximal portion of the elongation device, for example, using an actuator-driven traction cable. The traction cable can be actively placed under mechanical tension by the actuator to induce engagement.

[0024] The tension on the traction line may be limited. For example, the tension may be limited to an upper limit tension (also known as maximum tension), which is set based on one or more factors, such as the strength of the traction line, the strength of other structures bearing the generated forces and / or torques, the maximum output (force or torque) of the actuator, software-specified limits, the effect of the tension on the structural integrity or lifespan of the traction line, etc.

[0025] The traction cable may also encounter friction, which reduces the amount of force available to engage the engageable body parts. For example, the presence of friction may be uneven when a particular section of the traction cable is more worn than other sections, or when the traction cable is more curved due to the curvature of the flexible elongator. Friction may increase when a worn and / or highly curved section contacts the guide element (e.g., coil) surrounding the traction cable, compared to when an unworn or straight section contacts the guide element.

[0026] As described, friction and movement relative to tissue can cause struggling motion in flexible elongating devices. Examples of such struggling motion include incomplete execution of a commanded or desired engagement of a component that can engage the main body. Incomplete execution of a command can involve a portion of the commanded engagement being completed, but the entire command not yet being completed. Incomplete execution can also involve the command being completely unexecuted. This can result in the flexible elongating device bending less than the user commanded or desired.

[0027] In some implementations, the struggling movements of the flexible elongation device are detected and resolved. For example, incomplete execution of the command engagement is detected, and actions are taken to enable the command engagement to be completed.

[0028] The following provides a more detailed discussion, with reference to the accompanying drawings, of methods for operating medical systems and medical devices, and for resolving incomplete execution of desired command movements (e.g., engagement), including the benefits obtained.

[0029] See attached image. Figure 1This is a simplified diagram of a medical system 100 according to some embodiments. The medical system 100 can be applied to procedures such as surgery, diagnosis (e.g., biopsy), or treatment (e.g., ablation, electroporation, etc.). While some embodiments of these procedures are provided herein, any references to medical or surgical instruments and methods are non-limiting. The systems, instruments, and methods described herein can be used with animal or human cadavers, animal carcasses, parts of human or animal anatomy, for non-surgical diagnostics, and for industrial systems, general-purpose or special-purpose robotic systems, general-purpose or special-purpose remote operating systems, or robotic medical systems.

[0030] like Figure 1 As shown, the medical system 100 may include a manipulator assembly 102 that controls the operation of a medical device 104 during various surgical procedures performed on a patient P. The medical device 104 may extend into an internal part of the patient P through an opening within the patient P. The manipulator assembly 102 may be a remotely operated, non-remotely operated, or hybrid remotely and non-remotely operated assembly, having one or more degrees of freedom that can be electrically operated and / or one or more degrees of freedom that can be non-electrically operated (e.g., manually operated). The manipulator assembly 102 may be mounted to and / or positioned near the patient table T. A master assembly 106 enables an operator O (e.g., a surgeon, clinician, internist, or other user) to control the manipulator assembly 102. In some examples, the master assembly 106 enables the operator O to view the surgical site or other graphical or information displays. In some examples, the manipulator assembly 102 may be excluded from the medical system 100, and the device 104 may be directly controlled by the operator O. In some examples, the manipulator assembly 102 can be manually controlled by an operator O. Direct operator control may include various handles and operator interfaces for handheld operation of the instrument 104.

[0031] The main component 106 may be located at a surgeon's console near the patient table T where the patient P is located (e.g., in the same room as the patient table T), such as on the side of the patient table T. In some examples, the main component 106 is located away from the patient table T, such as in a different room or a different building. The main component 106 may include one or more control devices for controlling the manipulator component 102. The control devices may include any number of various input devices, such as joysticks, trackballs, rollers, steering pads, buttons, data gloves, trigger guns, manual controllers, voice recognition devices, motion or presence sensors, etc.

[0032] Manipulator assembly 102 supports medical device 104 and may include a kinematic structure of links providing a setting structure. Links may include one or more non-servo-controlled links (e.g., one or more links that can be manually positioned and locked in place) and / or one or more servo-controlled links (e.g., one or more links that can be controlled in response to commands, for example, from control system 112). Manipulator assembly 102 may include a plurality of actuators (e.g., motors) that drive inputs on medical device 104 in response to commands, for example, from control system 112. Actuators may include a drive system that moves medical device 104 in various ways when coupled to it. For example, one or more actuators may advance medical device 104 into a natural or surgically created anatomical opening. Actuators may control engagement of medical device 104, for example, by moving the distal end (or any other part) of medical device 104 in multiple degrees of freedom. These degrees of freedom may include three degrees of linear motion (e.g., linear motion along the X, Y, Z Cartesian axes) and three degrees of rotational motion (e.g., rotation about the X, Y, Z Cartesian axes). One or more actuators may control the rotation of the medical device about its longitudinal axis. Actuators may also be used to move the engageable end effector of the medical device 104 (e.g., to grasp tissue in the jaws of a biopsy device, etc.), or may be used to move or otherwise control tools inserted within the medical device 104 (e.g., imaging tools, ablation tools, biopsy tools, electroporation tools, etc.).

[0033] The medical system 100 may include a sensor system 108 having one or more subsystems for receiving information about the manipulator assembly 102 and / or the medical device 104. Such subsystems may include: a position sensor system (e.g., using an electromagnetic (EM) sensor or other type of sensor for detecting position or orientation); a shape sensor system for determining position, orientation, velocity, rate, pose, and / or shape along one or more segments and / or distal ends of the flexible body of the medical device 104; a visualization system (e.g., using a color imaging device, infrared imaging device, ultrasound imaging device, X-ray imaging device, fluorescence imaging device, computed tomography (CT) imaging device, magnetic resonance imaging (MRI) imaging device, or some other type of imaging device) for capturing images, for example, from the distal end of the medical device 104 or from some other location; and / or an actuator position sensor (e.g., a resolver, encoder, potentiometer, etc.) describing the rotation and / or orientation of the actuator controlling the medical device 104.

[0034] The medical system 100 may include a display system 110 for displaying images or representations of the surgical site and the medical device 104. The display system 110 and the main component 106 may be oriented so that a physician O can use telepresent perception to control the medical device 104 and the main component 106.

[0035] In some embodiments, medical device 104 may include a visualization system that includes an image capture component that records simultaneous or real-time images of the surgical site and provides the images to an operator O via one or more displays of display system 110. The image capture component may include various types of imaging devices. The simultaneous images may be, for example, two-dimensional or three-dimensional images captured by an endoscope positioned within the anatomical surgical site. In some examples, the visualization system may include an endoscope component that may be integrally or detachably coupled to medical device 104. Additionally or alternatively, a separate endoscope attached to a separate manipulator assembly may be used with medical device 104 to image the surgical site. The visualization system may be implemented as hardware, firmware, software, or a combination thereof that interacts with or is otherwise executed by one or more computer processors, such as control system 112.

[0036] Display system 110 can also display images of the surgical site and medical instruments, which can be captured by a visualization system. In some examples, medical system 100 provides operator O with a telepresented perception. For example, an image captured by an imaging device at the distal portion of medical instrument 104 can be presented by display system 110 to provide operator O with a perception of the distal portion of medical instrument 104. Inputs provided by operator O to master component 106 can move the distal portion of medical instrument 104 in a manner corresponding to the nature of the input (e.g., the distal end turns to the right when the trackball rolls to the right), and cause a corresponding change in the viewing angle of the image captured by the imaging device at the distal portion of medical instrument 104. Thus, operator O's telepresent perception is maintained when medical instrument 104 is moved using master component 106. Operator O can manipulate the hand controls of master component 106 and medical instrument 104 as if observing a workspace in a substantially realistic situation, simulating the experience of physically manipulating medical instrument 104 from within the patient's anatomy.

[0037] In some examples, the display system 110 may present a virtual image of the surgical site created using image data recorded preoperatively (e.g., before surgery performed by the medical device system 200) or intraoperatively (e.g., simultaneously with surgery performed by the medical device system 200), such as image data created using computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), fluoroscopy, thermal imaging, ultrasound, optical coherence tomography (OCT), thermal imaging, impedance imaging, laser imaging, nanotube X-ray imaging, etc. The virtual image may include two-dimensional, three-dimensional, or higher-dimensional images (e.g., including information based on time or rate). In some examples, one or more models are created based on the preoperative or intraoperative image dataset, and the virtual image is generated using one or more models.

[0038] In some examples, for the purpose of image-guided medical procedures, the display system 110 can display a virtual image generated based on the position of the tracking medical device 104. For example, the tracking position of the medical device 104 can be registered with a model generated using preoperative or intraoperative images (e.g., a dynamic reference), where different portions of the model correspond to different locations of the patient's anatomy. As the medical device 104 moves through the patient's anatomy, the registration is used to determine the portions of the model corresponding to the position and / or viewpoint of the medical device 104, and a virtual image is generated using the determined portions of the model. This allows a virtual image of the internal surgical site corresponding to the tracking position of the medical device 104 to be presented to the operator O from the viewpoint of the medical device 104.

[0039] The medical system 100 may further include a control system 112, which may include processing circuitry to implement some or all of the methods or functions discussed herein. The control system 112 may include at least one memory and at least one processor for controlling the operation of the manipulator assembly 102, medical device 104, main assembly 106, sensor system 108, and / or display system 110. The control system 112 may include instructions (e.g., a non-transitory machine-readable medium storing instructions) that, when executed by at least one processor, configure one or more processors to implement some or all of the methods or functions discussed herein. Although the control system 112... Figure 1 While shown as a single block, control system 112 may include two or more separate data processing circuits, with some processing performed at manipulator component 102, others at main component 106, and so on. In some examples, control system 112 may include other types of processing circuitry systems, such as application-specific integrated circuits (ASICs) and / or field-programmable gate arrays (FPGAs). Control system 112 may be implemented using hardware, firmware, software, or a combination thereof.

[0040] In some examples, the control system 112 may receive feedback from the medical device 104, such as force and / or torque feedback. In response to this feedback, the control system 112 may transmit a signal to the main component 106. In some examples, the control system 112 may transmit a signal instructing one or more actuators of the manipulator component 102 to move the medical device 104. In some examples, the control system 112 may transmit information about the feedback to the display system 110 for presentation or to perform other types of actions based on the feedback.

[0041] Control system 112 may include a virtual visualization system to provide navigational assistance to operator O when controlling medical device 104 during image-guided medical procedures. Virtual navigation using the virtual visualization system may be based on a preoperative or intraoperative dataset of the acquired anatomical pathways of patient P. Control system 112 or a separate computing device may, alone or in combination with operator input, use programmed instructions to transform recorded images into a model of the patient's anatomy. This model may include a segmented two-dimensional or three-dimensional synthetic representation of parts or entire anatomical organs or regions. The image dataset may be associated with the synthetic representation. The virtual visualization system may obtain sensor data from sensor system 108 for calculating the (e.g., approximate) position of medical device 104 relative to the anatomical structures of patient P. Sensor system 108 may be used to register and display medical device 104 and images recorded preoperatively or intraoperatively. For example, PCT disclosure WO 2016 / 191298 (published December 1, 2016, entitled "Systems and Methods of Registration for Image Guided Surgery") discloses an example system, which is incorporated herein by reference in its entirety.

[0042] During the virtual navigation process, sensor system 108 can be used to calculate the (e.g., approximate) position of medical device 104 relative to the anatomical structure of patient P. This position can be used to generate both a macroscopic (e.g., external) tracking image of the anatomical structure of patient P and a virtual internal image of the anatomical structure of patient P. The system may include one or more electromagnetic (EM) sensors, fiber optic sensors, and / or other sensors to register and display the medical device and preoperatively recorded medical images. For example, U.S. Patent No. 8,900,131 (filed May 13, 2011, entitled “Medical System Providing Dynamic Registration of a Model of an Anatomic Structure for Image-Guided Surgery”) discloses an example system, which is incorporated herein by reference in its entirety.

[0043] The medical system 100 may also include operating and support systems (not shown), such as lighting systems, steering and maneuvering control systems, flushing systems, and / or suction systems. In some embodiments, the medical system 100 may include more than one manipulator assembly and / or more than one main assembly. The exact number of manipulator assemblies may depend on factors such as the medical procedure and space constraints within the operating room. Multiple main assemblies may be located in the same location or may be positioned in separate locations. Multiple main assemblies allow more than one operator to control one or more manipulator assemblies in various combinations.

[0044] Figure 2A This is a simplified diagram of a medical device system 200 according to some embodiments. The medical device system 200 includes a flexible elongation device 202 (also referred to as elongation device 202), a drive unit 204, and a medical tool 226, which together serve as an example of the medical device 104 of the medical system 100. The medical system 100 can be a remote operating system, a non-remote operating system, or a hybrid of remote and non-remote operating systems, as shown in reference... Figure 1 As described above, the visualization system 231, tracking system 230, and navigation system 232 are also included. Figure 2A The diagram shows an example component of the control system 112 of the medical system 100. In some examples, the medical device system 200 can be used in non-remotely operated exploration procedures or in procedures involving routine manual operation of medical devices (e.g., endoscopy). The medical device system 200 can be used to collect (e.g., measure) a set of data points corresponding to a position within the anatomical passage of a patient (e.g., patient P).

[0045] The elongation device 202 is coupled to the drive unit 204. The elongation device 202 includes a channel 221 through which a medical instrument 226 can be inserted. The elongation device 202 navigates within the patient's anatomy to deliver the medical instrument 226 to the surgical site. The elongation device 202 includes a flexible body 216 having a proximal end 217 and a distal end 218. In some examples, the flexible body 216 may have an outer diameter of approximately 3 mm. Other flexible bodies may have larger or smaller outer diameters.

[0046] Medical device system 200 may include a tracking system 230 for determining the position, orientation, velocity, rate, pose, and / or shape of a flexible body 216 at its distal end 218 and / or along one or more segments 224 of the flexible body 216, as will be described in further detail below. Tracking system 230 may include one or more sensors and / or imaging devices. The flexible body 216 (e.g., the length between the distal end 218 and the proximal end 217) may include multiple segments 224. Tracking system 230 may be implemented using hardware, firmware, software, or a combination thereof. In some examples, tracking system 230 is... Figure 1 Part of the control system 112 shown.

[0047] The tracking system 230 can use a shape sensor 222 to track the distal end 218 and / or one or more segments 224 of the flexible body 216. The shape sensor 222 may include an optical fiber aligned with the flexible body 216 (e.g., disposed within an internal channel of the flexible body 216 or mounted externally along the flexible body 216). In some examples, the optical fiber may have a diameter of approximately 200 μm. In other examples, the diameter may be larger or smaller. The optical fiber of the shape sensor 222 can form an optical fiber bending sensor for determining the shape of the flexible body 216. Optical fibers including fiber Bragg gratings (FBGs) can be used to provide strain measurements of the structure in one or more dimensions. Various systems and methods for monitoring the shape and relative position of optical fibers in three dimensions, applicable to some embodiments, are described in U.S. Patent Application Publication No. 2006 / 0013523 (filed July 13, 2005, entitled "Fiber optic position and shape sensing device and method relating thereto"), U.S. Patent No. 7,772,541 (filed March 12, 2008, entitled "Fiber Optic Position and / or Shape Sensing Based on Rayleigh Scatter"), and U.S. Patent No. 8,773,650 (filed September 2, 2010, entitled "Optical Position and / or Shape Sensing"), all of which are incorporated herein by reference in their entirety. In some embodiments, the sensor may employ other suitable strain sensing techniques, such as Rayleigh scattering, Raman scattering, Brillouin scattering, and fluorescence scattering.

[0048] In some examples, other techniques may be used to determine the shape of the flexible body 216. For example, the history of the position and / or pose of the distal end 218 of the flexible body 216 may be used to reconstruct the shape of the flexible body 216 over time intervals (e.g., as the flexible body 216 advances or retracts within a patient's anatomy). In some examples, the tracking system 230 may alternatively and / or additionally use a position sensor system 220 to track the distal end 218 of the flexible body 216. The position sensor system 220 may be a component of an EM sensor system, wherein the position sensor system 220 includes one or more position sensors. Although the position sensor system 220 is shown proximity to the distal end 218 of the flexible body 216 to track the distal end 218, the number and position of the position sensors in the position sensor system 220 may vary to track different regions along the flexible body 216. In one example, the position sensors include conductive coils that can withstand externally generated electromagnetic fields. Each coil of the position sensor system 220 may generate an induced electrical signal having characteristics that depend on the position and orientation of the coil relative to the externally generated electromagnetic field. Position sensor system 220 can measure one or more position coordinates and / or one or more orientation angles associated with one or more portions of flexible body 216. In some examples, position sensor system 220 can be configured and positioned to measure six degrees of freedom, such as three position coordinates X, Y, Z and three orientation angles indicating pitch, yaw, and roll of a reference point. In some examples, position sensor system 220 can be configured and positioned to measure five degrees of freedom, such as three position coordinates X, Y, Z and two orientation angles indicating pitch and yaw of a reference point. Further description of the position sensor system applicable to some embodiments is provided in U.S. Patent No. 6,380,732 (filed August 11, 1999, entitled "Six-Degree of Freedom Tracking System Having a Passive Transponder on the Object Being Tracked"), which is incorporated herein by reference in its entirety.

[0049] In some implementations, the tracking system 230 may alternatively and / or additionally rely on a set of pose, position, and / or orientation data stored at points on the elongation device 202 and / or medical instrument 226, captured during one or more cycles of alternating movement (e.g., breathing). This stored data can be used to develop shape information about the flexible body 216. In some examples, a series of position sensors (not shown)—such as EM sensors like those in position sensor 220 or some other type of position sensor—can be positioned along the flexible body 216 and used for shape sensing. In some examples, a history of data acquired during surgery from one or more of these position sensors can be used to represent the shape of the elongation device 202, particularly where the anatomical passage is typically static.

[0050] Figure 2B This is a simplified diagram of a medical tool 226 within an elongation device 202 according to some embodiments. The flexible body 216 of the elongation device 202 may include a channel 221 sized and shaped to receive the medical tool 226. In some embodiments, the medical tool 226 may be used for procedures such as diagnostics, imaging, surgery, biopsy, ablation, illumination, irrigation, aspiration, electroporation, etc. The medical tool 226 can be deployed through the channel 221 of the flexible body 216 and operate at a surgical site within an anatomical structure. The medical tool 226 may be, for example, an image capture probe, a biopsy tool (e.g., a needle, gripper, brush, etc.), an ablation tool (e.g., a laser ablation tool, a radiofrequency (RF) ablation tool, a cryoablation tool, a thermal ablation tool, a heated liquid ablation tool, etc.), an electroporation tool, and / or another surgical, diagnostic, or therapeutic tool. In some examples, the medical tool 226 may include an end effector with a single working member, such as a scalpel, a blunt blade, an optical fiber, an electrode, etc. Other end effector types can include, for example, forceps, grippers, scissors, sutures, clamps, etc. Other end effectors can also include electrically activated end effectors, such as electrosurgical electrodes, transducers, sensors, etc.

[0051] Medical tool 226 may be a biopsy tool for removing sample tissue or cell samples from a target anatomical location. In some examples, the biopsy tool is a flexible needle. The biopsy tool may also include a sheath that surrounds the flexible needle to protect the needle and the inner surface of the channel 221 when the biopsy tool is within the channel 221. Medical tool 226 may be an image capture probe that includes a distal portion having a stereo or single-field-of-view camera, which may be positioned at or near the distal end 218 of the flexible body 216 for capturing images (e.g., still or video images). The captured images may be processed by visualization system 231 for display and / or provided to tracking system 230 to support tracking of the distal end 218 of the flexible body 216 and / or one or more segments 224 of the flexible body 216. The image capture probe may include a cable for transmitting the captured image data, which is coupled to an imaging device at the distal portion of the image capture probe. In some examples, the image capture probe may include a bundle of optical fibers, such as a fiber optic endoscope, coupled to a closer imaging device, such as the visualization system 231. The image capture probe may be monospectral or multispectral, capturing image data in one or more of the visible, near-infrared, infrared, and / or ultraviolet spectra. The image capture probe may also include one or more light emitters that provide illumination to facilitate image capture. In some examples, the image capture probe may use ultrasound, X-ray, fluoroscopy, CT, MRI, or other types of imaging techniques.

[0052] In some examples, an image capture probe is inserted within the flexible body 216 of the elongation device 202 to facilitate visual navigation of the elongation device 202 to the surgical site, and then the image capture probe is replaced within the flexible body 216 with another type of medical instrument 226 for performing the surgery. In some examples, the image capture probe may be located together with another type of medical instrument 226 within the flexible body 216 of the elongation device 202 to facilitate simultaneous image capture and tissue intervention, for example, within the same channel 221 or in different channels. The medical instrument 226 may advance from an opening in the channel 221 to perform the surgery (or some other function) and then retract into the channel 221 upon completion of the surgery. The medical instrument 226 may be removed from the proximal end 217 of the flexible body 216 or along the flexible body 216 from another optional instrument port (not shown).

[0053] In some examples, the extension device 202 may include integrated imaging capabilities instead of utilizing a removable image capture probe. For example, the imaging device (or fiber bundle) and light emitter may be located at the distal end 218 of the extension device 202. The flexible body 216 may include one or more dedicated channels carrying cables and / or optical fibers between the distal end 218 and the visualization system 231. Here, the medical device system 200 can perform imaging and tooling operations simultaneously.

[0054] In some examples, the medical tool 226 is capable of controlled engagement. The medical tool 226 may house a cable (also referred to as a traction cable), linkage, or other actuation control (not shown), extending between its proximal and distal ends to controllably bend the distal end of the medical tool 226, such as those discussed herein with respect to the flexible elongation device 202. The medical tool 226 may be coupled to the drive unit 204 and the manipulator assembly 102. In these examples, the elongation device 202 may be excluded from the medical device system 200, or may be a flexible device without controlled engagement. Steering maneuvers or instruments applicable to some embodiments are further described in detail in U.S. Patent No. 7,316,681 (filed October 4, 2005, entitled “Articulated Surgical Instrument for Performing Minimally Invasive Surgery with Enhanced Dexterity and Sensitivity”) and U.S. Patent No. 9,259,274 (filed September 30, 2008, entitled “Passive Preload and Capstan Drive for Surgical Instruments”), which are incorporated herein by reference in their entirety.

[0055] The flexible body 216 of the extension device 202 may also, or alternatively, accommodate a cable, linkage, or other steering control (not shown) extending between the drive unit 204 and the distal end 218 to controllably bend the distal end 218, such as, for example, by Figure 2A The distal end 218 is depicted by a dashed line 219. In some examples, at least four cables are used to provide independent up-and-down steering control to control the pitch of the distal end 218 and left-and-right steering control to control the yaw of the distal end 281. In these examples, the flexible elongation device 202 may be a steerable maneuverable conduit. Examples of steerable maneuverable conduits suitable for some embodiments are described in detail in PCT Publication WO 2019 / 018736 (published January 24, 2019, entitled "Flexible Elongate Device Systems and Methods"), which is incorporated herein by reference in its entirety.

[0056] In embodiments where the elongation device 202 and / or medical tool 226 is actuated by a remotely operated component (e.g., manipulator component 102), the drive unit 204 may include a drive input removably coupled to and receiving power from a drive element (e.g., an actuator) of the remotely operated component. In some examples, the elongation device 202 and / or medical tool 226 may include a grasping feature, a manual actuator, or other components for manually controlling the movement of the elongation device 202 and / or medical tool 226. The elongation device 202 may be steerable, or alternatively, it may be non-steerable, without an integrated mechanism for operator control of bending of the distal end 218. In some examples, one or more channels 221 (which may also be referred to as lumens) may be defined by the inner wall of the flexible body 216 of the elongation device 202, through which the medical tool 226 may be deployed and used at a target anatomical location.

[0057] In some examples, medical device system 200 (e.g., extension device 202 or medical tool 226) may include flexible bronchial instruments, such as bronchoscopes or bronchial tubes, for the examination, diagnosis, biopsy, and / or treatment of the lungs. Medical device system 200 may also be adapted to navigate and treat other tissues within any anatomical system of a variety of anatomical systems via naturally or surgically generated access channels, including the colon, intestine, kidneys and renal calyces, brain, heart, circulatory system including the vascular system, etc.

[0058] Information from tracking system 230 can be sent to navigation system 232, where it can be combined with information from visualization system 231 and / or a preoperatively acquired model to provide real-time location information to physicians, clinicians, surgeons, or other operators. In some examples, the real-time location information can be displayed on display system 110 for control of medical device system 200. In some examples, navigation system 232 can utilize the location information as feedback for locating medical device system 200. Various systems for registering and displaying surgical instruments and surgical images using fiber optic sensors, applicable to some embodiments, are provided in U.S. Patent No. 8,900,131 (filed May 13, 2011, entitled “Medical System Providing Dynamic Registration of a Model of an Anatomic Structure for Image-Guided Surgery”), which is incorporated herein by reference in its entirety.

[0059] Figure 3A and Figure 3BThis is a simplified side view of a medical device mounted on an insertion assembly, according to some embodiments, in patient coordinate space. Figure 3A and 3B As shown, the surgical environment 300 may include a patient P positioned on a patient table T. Patient P may be stationary within the surgical environment 300 because overall patient movement is restricted by sedation, restraint, and / or other means. Periodic anatomical movements of patient P (including respiratory and cardiac movements) may continue. Within the surgical environment 300, a medical device 304 is used to perform medical procedures, which may include, for example, surgery, biopsy, ablation, illumination, irrigation, aspiration, or electroporation. The medical device 304 may also be used to perform other types of procedures, such as a registration process that associates position, orientation, and / or pose data captured by a sensor system 108 with a desired (e.g., anatomical or systemic) reference frame. The medical device 304 may be, for example, medical device 104. In some examples, the medical device 304 may include an elongation device 310 (e.g., a catheter) coupled to an instrument body 312. The elongation device 310 includes one or more channels sized and shaped to receive medical instruments.

[0060] The elongation device 310 may also include one or more sensors (e.g., components of sensor system 108). In some examples, a shape sensor 314 may be fixed at a proximal point 316 on the instrument body 312. The proximal point 316 of the shape sensor 314 may move with the instrument body 312, and the position of the proximal point 316 relative to a desired reference frame may be known (e.g., via a tracking sensor or other tracking device). The shape sensor 314 may measure the shape from the proximal point 316 to another point (e.g., the distal end 318 of the elongation device 310). The shape sensor 314 may be aligned with the elongation device 310 (e.g., disposed within an internal channel or mounted externally). In some examples, the shape sensor 314 may be an optical fiber used to generate shape information of the elongation device 310.

[0061] In some examples, position sensors (e.g., EM sensors) may be incorporated into medical device 304. A series of position sensors may be positioned along the flexible elongation device 310 and used for shape sensing. Position sensors may be used in place of or in conjunction with shape sensor 314, for example, to improve the accuracy of shape sensing or to verify shape information.

[0062] The extension device 310 may accommodate cables, links, or other steering control mechanisms that extend between the instrument body 312 and the distal end 318 to controllably bend the distal end 318. In some examples, at least four cables are used to provide independent up-and-down steering control to control the pitch of the distal end 318 and left-and-right steering control to control the yaw of the distal end 318. The instrument body 312 may include a drive input that is removably coupled to and receives power from a drive element (e.g., an actuator) of the manipulator assembly.

[0063] The instrument body 312 may be coupled to the instrument holder 306. The instrument holder 306 may be mounted to an insertion stage 308 fixed within the surgical environment 300. Alternatively, the insertion stage 308 may be movable but has a known position within the surgical environment 300 (e.g., via a tracking sensor or other tracking device). The instrument holder 306 may be a component of a manipulator assembly (e.g., manipulator assembly 102) coupled to the medical device 304 to control insertion motion (e.g., movement along insertion axis A) and / or movement of the distal end 318 of the extension device 310 in multiple directions, such as yaw, pitch, and / or roll. The instrument holder 306 or the insertion stage 308 may include actuators, such as servo motors, for controlling the movement of the instrument holder 306 along the insertion stage 308.

[0064] Sensor device 320 (which may be a component of sensor system 108) can provide information about the position of instrument body 312 as it moves along insertion axis A relative to insertion stage 308. Sensor device 320 may include one or more rotary transformers, encoders, potentiometers, and / or other sensors that measure the rotation and / or orientation of actuators controlling the movement of instrument carrier 306, thereby indicating the movement of instrument body 312. In some embodiments, insertion stage 308 has, for example, […]. Figure 3A and Figure 3B The linear track is shown. In some embodiments, the insertion stage 308 may have a curved track or a combination of curved track segments and linear track segments.

[0065] Figure 3A The instrument body 312 and instrument holder 306 are shown in the retracted position along the insertion stage 308. In this retracted position, the proximal point 316 is located at position L0 on the insertion axis A. The position of the proximal point 316 can be set to zero and / or other reference values ​​to provide a basic reference (e.g., corresponding to the origin of the desired reference system) to describe the position of the instrument holder 306 along the insertion stage 308. In the retracted position, the distal end 318 of the extension device 310 can be positioned precisely within the inlet orifice of the patient P. Also in the retracted position, data captured by the sensor device 320 can be set to zero and / or other reference values ​​(e.g., I = 0). Figure 3BIn this configuration, the instrument body 312 and instrument holder 306 have advanced along the linear track of the insertion stage 308, and the distal end 318 of the elongation device 310 has advanced into the patient P. At this advanced position, the proximal point 316 is at position L1 on the insertion axis A. In some examples, the rotation and / or orientation of the actuator, measured by the sensor device 320 indicating the movement of the instrument holder 306 along the insertion stage 308 and / or by one or more position sensors associated with the instrument holder 306 and / or the insertion stage 308, can be used to determine the position L1 of the proximal point 316 relative to position L0. In some examples, position L1 can also serve as an indicator of the distance or insertion depth of the distal end 318 of the elongation device 310 into the channel of insertion into the anatomical structure of the patient P.

[0066] As previously described, actuation along the engagement degree of freedom can involve engagement of the engageable body portion of the flexible elongation device (e.g., the distal portion of the flexible elongation device). Engagement of the engageable body portion can be driven from the proximal portion of the elongation device, for example, using a traction line driven by an actuator. The traction line can be actively placed under mechanical tension by the actuator to induce engagement.

[0067] The tension on the traction line used to drive the engageable body portion via an actuator at the proximal portion of the flexible elongation device may be limited. For example, the tension may be capped at a maximum tension based on the strength of the traction line, the maximum output (force or torque) of the actuator, software-specified limits (e.g., based on control considerations), etc. In one configuration, the tension can be dynamically capped to establish an isometrically constrained torque in the engagement space of the engageable body portion, as discussed further below.

[0068] The traction cable may also encounter friction, which reduces the amount of force available to engage the mating body parts. For example, the presence of friction may be uneven when a particular section of the traction cable wears more than other sections. Friction may increase when such a worn section contacts a guide element (e.g., a coil) surrounding the traction cable, compared to when an unworn section contacts such an element.

[0069] As described, friction can lead to incomplete engagement of the engaged body parts, whether commanded or desired. Specifically, a user may provide a command trajectory for commanding engagement (e.g., a specific degree of pitch and / or yaw engagement of the body parts) using an input device, but the resulting actual engagement of the body parts may be less than desired. This problem can arise particularly when a certain force / torque is required to engage the engaged body parts, such as in the presence of adjacent tissue providing resistance to engagement. In this case, the maximum force on the traction cable may be insufficient to overcome the combination of tissue resistance and traction cable friction, resulting in incomplete engagement.

[0070] Figure 4 A flowchart of a method for detecting and resolving such incomplete engagement, according to an embodiment of this disclosure, is shown. The method can be implemented using instructions stored on a non-transient medium, which can be executed by a computing system (e.g., computing system 120).

[0071] Although Figure 4 The blocks in the code are presented and described sequentially, but some or all of the blocks can be executed in a different order, can be combined or omitted, and some or all of the blocks can be executed in parallel. Furthermore, the blocks can be executed actively or passively.

[0072] Transfer to Figure 4 In block 410, according to some embodiments, a set of actuators controlling the manipulator assembly are used to change the engagement state of the flexible elongation device. The flexible elongation device can be a catheter or endoscope in a medical system, as described above. Figure 1 , Figure 2A , Figure 2B , Figure 3A and Figure 3B And as described in the accompanying description. In particular, the flexible elongation device can be a medical device that can be driven using one or more actuators along one or more engagement degrees of freedom (e.g., about the pitch axis and / or yaw axis). In some embodiments, the distal portion of the flexible elongation device is engaged. For example, in the case where the flexible elongation device is a steerable manipulator catheter, the catheter ridge can form an engageable portion. Drives along the engagement degrees of freedom can be performed to navigate the distal end of the flexible elongation device toward the target tissue and / or orient the end effector toward the target tissue, thereby performing medical procedures such as biopsy, ablation, or electroporation. In some embodiments, block 410 is executed in a cycle in which a command engagement state of the flexible elongation device is obtained from a user input device, wherein the user can specify the command engagement state using a joystick, trackball, etc., for example in the form of pitch and / or yaw angles. The operations performed in block 410 can control the actuators such that the actual engagement state of the flexible elongation device follows the command engagement state. The trajectory employed during the continuous repetition of block 410 produces an engagement trajectory.

[0073] One or more actuators corresponding to one or more traction lines can be used to engage the flexible extension device along the engagement trajectory from an initial engagement state to a commanded engagement state. The control scheme can govern the control of the actuators and can include various parameters such as upper tension (e.g., maximum tension), lower tension (e.g., minimum tension), isotropic limits (e.g., established by adjusting the upper tension), and possibly other engagement parameters, as discussed below. For example, a minimum tension can be specified to prevent traction line slack. The maximum tension can be specified by software based on, for example, the strength or durability of the traction lines. The maximum tension can also be a result of the maximum force or torque output of the corresponding actuator. Using isotropic limits, the force, torque, or tension limits specified by the software can be further dynamically adjusted according to the engagement direction to achieve an equidistant engagement torque, i.e., a constant maximum engagement torque, independent of the engagement direction. For example, in cases where engagement includes pure pitch or yaw components, a single actuator can provide a certain torque. For engagements including both pitch and yaw components, the actuator torque can be limited such that the total torque in the resulting direction does not exceed the torque available in the pure pitch or yaw direction. Without isotropic constraints, the total torque produced by the combination of torques applied in both the pitch and yaw directions may be higher than the torque of the pure pitch or yaw components.

[0074] In block 420, according to some embodiments, it is determined whether a command engagement state of the flexible elongation device is achievable. More specifically, it can be determined whether a command engagement state can be achieved by controlling the actuator without applying an upper limit tension to the traction line controlled by the actuator. This determination can be performed based on a comparison of the command engagement (e.g., based on a reading obtained from an encoder at a user input device such as a trackball) with a measurement of the actual engagement of the flexible elongation device (e.g., the engagement portion). The actual engagement can be determined in various ways, including using various types of sensors, such as shape sensors, one or more EM sensors, etc. A command engagement state is not achievable when incomplete engagement on the command trajectory from the initial engagement state to the command engagement state is detected based on a position tracking error at the command engagement state. In an example of an incomplete trajectory, the tension applied by the actuator (e.g., as can be measured by an encoder) may be at the maximum tension that should result in the maximum bending amount, but the actual engagement state has a bending amount smaller than the maximum bending. Detection can also be performed over time, for example by monitoring the cumulative error of the actual engagement as the actual engagement deviates from the command engagement. Furthermore, detection can be performed for multiple engagement directions and actuators.

[0075] Figure 5AA scenario is illustrated where the actual engagement state differs from the commanded engagement state. In scenario 500, the output of the input device (e.g., a trackball encoder signal), the commanded engagement state (e.g., commanded pitch and / or yaw), and the actual engagement state (e.g., measured pitch and / or yaw) are shown over time. These signals can be the result of a user continuously providing input in the same direction at the input device. This directly causes the output of the input device to continuously increase, as shown. The output of the input device may be limited by a saturation function before being used to generate the commanded engagement state. In the example shown, the saturation limit has been reached, and therefore the maximum tension is applied by the actuator. Thus, the commanded engagement state remains unchanged. Without the friction or external force issues described, the actual engagement state would reach the commanded engagement state while the actuator provides maximum tension. However, in scenario 500, although the actuator provides maximum tension, the actual engagement state fails to reach the commanded engagement state, for example, due to reasons discussed previously. Figure 5A As shown, the detection that the actual engagement state fails to reach the commanded engagement state can be based on the difference between the commanded engagement state and the actual engagement state, but it can also be based on a further increase in the output of the input device without the actual engagement state following suit. Here, the actuator will be required to apply tension exceeding the maximum to achieve the commanded actuation state.

[0076] Although Figure 4 The flowchart shows the sequential execution of blocks 410 and 420, but block 420 can be executed in parallel with block 410 to provide monitoring of the engagement status during the ongoing engagement of the flexible elongation device.

[0077] When it is determined that the commanded engagement state cannot be achieved by controlling the actuator or similarly for a set of actuators used to change the engagement state in block 410 without applying more than the maximum tension, the execution of the method can proceed to block 430.

[0078] As previously mentioned, a commanded engagement state may prove unachievable if none of the actuators exceed the maximum tension due to friction or resistance (high enough to prevent the actuators controlled by the control scheme from engaging to achieve the commanded engagement state). In some implementations, a higher actuator torque than corresponding to the maximum tension will typically be used to complete the movement along a direct trajectory toward the commanded engagement state. However, exceeding the maximum tension may not be desirable. Therefore, one or more other types of control responses can be used to achieve the commanded engagement state without any actuator applying tension exceeding the maximum tension.

[0079] Figure 5BExamples of actual engagement and command engagement of a flexible elongating device according to some embodiments are shown. In example 510, a tissue barrier 512 prevents the flexible elongating device 518 from fully engaging to reach the command engagement state 514. Instead, in the example shown, the flexible elongating device 518 does not engage beyond the actual engagement state 516. Thus, in this example, the presence of the tissue barrier 512 makes the command trajectory (towards the command engagement state 514) unattainable. The tissue barrier 512 may, for example, contact the flexible elongating device 518, such that friction between the tissue barrier 512 and the flexible elongating device 518 prevents further engagement. Alternatively, internal friction along the traction line may also result in the inability to reach the command engagement state 514 on the command trajectory. For example, an increase in internal friction may occur as the flexible elongating device wears over time. For example, the traction line and / or traction line support structure may be coated with a friction-reducing material (e.g., Teflon), which may eventually wear off. The resulting increase in friction reduces the amount of force or torque available for engagement of the flexible elongating device. Because certain sections of the traction line wear more than other sections of the same traction line, the resulting friction may be uneven and may depend on the degree and direction of engagement. When such a worn section comes into contact with a guiding element (e.g., coil) surrounding the traction line, friction may increase compared to contact with an unworn section. Incomplete engagement can also result from internal components of the flexible extension device providing resistance to engagement. For example, inserting an instrument into the lumen of the flexible extension device can increase the overall stiffness of the device. If such components are placed under tension only in certain engagement directions, the internal resistance in those engagement directions may be greater than in others.

[0080] In block 430, the control of the flexible elongation device is updated to allow a command engagement state to be achieved. In some embodiments, the amount of tension applied to one or more traction lines is varied without exceeding the maximum tension. For example, if it is determined that command engagement cannot be achieved by controlling the first actuator without applying a tension exceeding the upper limit to the first traction line, then in block 430, a second actuator can be controlled to vary the amount of tension applied to the second traction line without applying an upper limit to the first traction line, thereby achieving a command engagement state. The second traction line may be responsible for engagement along an axis different from that of the first traction line. As a result of this variation, the flexible elongation device can employ different engagement trajectories to the command engagement state, potentially avoiding the reasons for initial failure to achieve the command engagement state. Engagement in different directions may have different implications, which may contribute to achieving the command engagement state.

[0081] For example, Figure 5C and Figure 5DThis is an illustration of adjusting a direct engagement trajectory to a non-direct engagement trajectory according to some embodiments. A non-direct engagement trajectory can be used when a direct engagement trajectory might fail, for example, due to friction between the traction line and other structural features of the flexible elongating device around or near the traction line. A non-direct engagement trajectory between a first (e.g., initial) engagement state and a second (e.g., command) engagement state refers to an engagement trajectory that includes movement in opposite directions along one or more engagement axes (e.g., pitch or yaw). A non-direct engagement trajectory includes offset movements or multiple offset movements that contribute to the ability of the flexible elongating device to reach the second engagement state. In contrast, a direct engagement trajectory between the first and second engagement states refers to an engagement trajectory that includes movement in a single direction only along any engagement axis (e.g., pitch, yaw, or any other direction, such as a combination of pitch and yaw). Here, there is no offset movement on any engagement axis, which provides effective movement without struggling or incomplete movement.

[0082] exist Figure 5C In this example, the user input specifies engagement to command engagement state 521. Engagement follows a direct engagement trajectory 523 (in this example, entirely in the yaw direction), but terminates at initial engagement state 522, thus failing to reach command engagement state 521. When initial engagement state 522 on the command trajectory is detected as incomplete, a non-direct engagement trajectory 524 is determined. The non-direct engagement trajectory involves engagement components in the pitch direction. Therefore, while the direct engagement trajectory may already be driven by a single actuator for the yaw direction (or two actuators in an anti-tank scheme), the non-direct engagement trajectory also involves a second actuator (or two actuators in an anti-tank scheme) for the pitch component. Assuming a traction line for pitch and a traction line for yaw (or, in an anti-tank scheme, a pair of traction lines for pitch and a pair of traction lines for yaw), the non-direct engagement trajectory 524 could be the result of operating the actuator associated with the pitch direction to increase and decrease the tension on the corresponding traction line. In the example shown, first, a pitch component is superimposed in a direction away from the yaw axis, followed by a pitch component toward the yaw axis. More generally, the superimposed components can be in a direction orthogonal to the direct engagement trajectory. The superposition of the pitch components can be performed while the actuator associated with the yaw direction is continuously commanded to maintain the command engagement state 521. During the superposition, the tension on the traction line associated with engagement toward the command engagement state can be at its upper limit or maximum tension. As the components in the pitch direction are superimposed as shown, the actual engagement can gradually advance from the initial engagement state 522 to the command engagement state 521. The resulting changed trajectory deviates directionally from the command trajectory. The first segment diverges from the command trajectory with a pitch component away from the command trajectory, and the second segment converges to the command trajectory with a pitch component toward the command trajectory and terminates at the command engagement state.

[0083] More generally, a direct engagement trajectory can include pitch and / or yaw components that are not offset from each other in a single direction. Therefore, the resulting trajectory can be a substantially straight trajectory in any direction within the engagement space (e.g., with only minor deviations from a straight path due to manual user input). In contrast, a non-direct engagement trajectory can involve pitch components moving in opposite offset directions or yaw components moving in opposite offset directions, thus enabling command engagement using a non-direct engagement trajectory.

[0084] The altered trajectory reaches a command engagement state that is unattainable on the command trajectory for various possible reasons:

[0085] - As previously mentioned, the engagement of the flexible elongation device can be driven by applying tension to the traction line. In such cases... Figure 5C In the illustrated yaw-pitch configuration, four traction cables can exist (one pair for anti-pitch control and one pair for anti-yaw control). Each traction cable may encounter friction, and this friction may be uneven, with some sections of the coil or cable wearing more wear than others. This causes the frictional force to depend on the degree and direction of engagement. Therefore, when the altered trajectory differs from the original trajectory, the encountered friction may be less. Figure 5D Example 530 of a coil for a traction line is provided. The traction line is shown in its original position 533, which corresponds to a wear area of ​​increased friction on the coil 531. The traction line can be in the original position 533 to execute command trajectory 523. The traction line is further shown in a changed position 534, which the traction line can be in at least temporarily during the execution of alternative trajectory 524.

[0086] -in such Figure 5C In the example shown, the original trajectory is only in the yaw direction. A single actuator can be activated to drive this motion in the yaw direction. As mentioned earlier, this single actuator may be limited in its force or torque output. Figure 5C In the example, for instance, due to friction, the actuator output is insufficient to achieve the command engagement state. The altered trajectory involves motion in the pitch and yaw directions. Therefore, two actuators are involved. The two actuators generate a higher output than a single actuator would produce, thus contributing to achieving the command engagement state.

[0087] - When the tissue comes into contact with the flexible elongation device and prevents the original trajectory from being completed, a changed trajectory in a different direction can result in less friction or resistance in the tissue.

[0088] continue Figure 4The discussion of block 430 of the method shown illustrates that control of one or more actuators to alter the engagement state of the flexible elongation device can be performed in different ways. As previously described, the amount of tension applied to one or more tension members is altered to cause the flexible elongation device to engage in different directions, thereby potentially avoiding the cause of initial failure to achieve the commanded engagement state. In another example, the tension is altered to generate, as... Figure 5E and Figure 5F The indirect bonding trajectory shown.

[0089] exist Figure 5E In Example 540, after determining that engagement cannot proceed beyond the initial engagement state 542 and that the commanded engagement state 541 cannot be reached on the direct engagement trajectory 543, an indirect engagement trajectory 544 is selected to reach the commanded engagement state 541. The indirect engagement trajectory 544 comprises repetitions of segments that alternately diverge from and converge back to the commanded trajectory in alternating directions. Assuming opposing traction lines (one pair for pitch and one pair for yaw), the indirect engagement trajectory 544 could be the result of alternating operation of the actuators associated with the pitch direction. This can be performed while the actuators associated with the yaw direction are continuously commanded to maintain the commanded engagement state 541. When the components in the pitch direction are superimposed as shown, the actual engagement can gradually advance from the initial engagement state 542 to the commanded engagement state 541.

[0090] exist Figure 5F In Example 550, after determining that engagement cannot proceed beyond the initial engagement state 552 and that the command engagement state 551 cannot be reached on the direct engagement trajectory 553, an indirect engagement trajectory 554 is selected to reach the command engagement state 551. The indirect engagement trajectory 554 comprises repetitions of segments that alternately diverge from and converge back to the command trajectory in the same direction. Assuming a traction line for pitch and a traction line for yaw (or, in a countermeasures control scheme, a pair of traction lines for pitch and a pair of traction lines for yaw), the indirect engagement trajectory 554 can be the result of operating an actuator associated with the pitch direction, as previously referenced. Figure 5C This can be performed while the actuator associated with the yaw direction is continuously commanded to maintain command engagement state 551. Actual engagement can gradually progress from the initial engagement state 552 to the command engagement state 551 as the pitch components are superimposed as shown.

[0091] As previously referenced Figure 5C and Figure 5D The described possible reasons, Figure 5E and Figure 5F The changed trajectory reaches the command engagement state.

[0092] In Examples 540 and 550, the execution of repeating segments can be coordinated with user input at a user input device. For example, suppose the user input device providing the command trajectory to the command engagement is a trackball. In such a configuration, the user can input the command trajectory incrementally, for example, based on the inherent range of motion limitations of the trackball, which require the user to repeatedly reposition their finger on the trackball. In this case, each of the repeating segments can be executed as the user manipulates the trackball to complete an increment of the command trajectory.

[0093] like Figures 5C to 5F As shown, indirectly coupled trajectories can include variations in directional components at different frequencies. Figure 5C The data shows a lower frequency variation, while Figure 5E and Figure 5F The higher frequency variation is shown. Additional variations can be applied. For example, suppose there is a first directional component along an axis (e.g., the yaw axis) and a second directional component along the pitch axis, and the contributions in these two directions can vary such that the first engagement component is more dominant than the second engagement component in one engagement direction, and the second engagement component is more dominant than the first engagement component in another engagement direction.

[0094] Although Figures 5B to 5F The behavior shown does not require an antagonistic drive scheme, but embodiments of this disclosure are compatible with such implementations. In one example, two traction lines on opposite sides can control engagement along a single axis. In one embodiment, a total of four traction lines exist, with pairs of traction lines controlling the orthogonal pitch and yaw axes of the engagement portion of the flexible extension device. In such an implementation, an antagonistic actuator can be used to both drive engagement and set or maintain a minimum required tension on the traction lines. When incomplete execution of the command engagement is detected, the minimum required tension can be reduced, thereby increasing the amount of torque available for engagement.

[0095] In addition, although Figures 5C to 5F In the illustrations, the direct engagement trajectory is shown as aligned with the yaw axis, but embodiments of this disclosure are generally described as direct engagement trajectories in any direction.

[0096] continue Figure 4 The discussion of block 430 of the method shown also demonstrates that a command engagement state can be achieved even with unoriented deviations from the direct engagement trajectory. This will be referred to... Figure 5G Let's have a discussion.

[0097] Figure 5GThe modulation of actuator torque or force to achieve the command engagement state is shown. A scenario 560 involving counteracting drive along pitch (both actuators) and yaw (both actuators) is shown. More generally, counteracting drive can be performed by pairs of actuators along any common engagement axis. The torque of the equidistant constraint is visualized, where the torque limit is the same and independent of direction. Therefore, the torque is limited to circular regions in the pitch / yaw planes 561, 562. Torque limit 561 is a result of the minimum required tension on the traction line. In the counteracting drive scheme where a minimum required tension exists, the total torque available for engagement is reduced due to the relative torque associated with the minimum required tension on the relative traction lines. Minimum tension can be applied for various reasons, such as to prevent traction line slack. Torque limit 562 is a result of reducing the minimum tension without increasing the upper limit tension, while still requiring equidistant torque limits. For example, the minimum tension is reduced to zero, thereby completely eliminating the torque generated on the relative traction lines. Reducing only the minimum tension along the common engagement axis can allow engagement to be completed on a direct engagement trajectory. Reducing the minimum tension can also facilitate engagement on indirect engagement tracks. Alternatively, a higher torque limit 562, compared to torque limit 561, can also result in an increased upper limit tension (maximum tension) on the traction line. As an additional or alternative step, the equidistant torque requirement can be disabled, as indicated by torque limit 563. Disabling the equidistant torque constraint allows each actuator to apply tension up to the maximum tension on each of the traction lines, regardless of the engagement direction in the pitch-yaw space. While the elimination of the equidistant torque requirement does not result in a further increase in torque along the pitch and yaw axes, there is an increase in torque for any off-axis direction due to the combined torque contribution from both actuators without exceeding the maximum tension. The maximum torque can be achieved at a 45° angle, where both actuators (one yaw actuator and one pitch actuator) contribute equally.

[0098] Therefore, an indirect engagement trajectory, including segments oriented such that they involve equal contributions to pitch and yaw components, can be a trajectory toward a target engagement state that can be achieved with maximum torque.

[0099] Continuing the discussion of block 430, several different methods for changing the engagement state have been described. Upon entering block 430, for example after determining, based on the position tracking error at the command engagement state, that the initial engagement state of the flexible elongating device on the command trajectory is incomplete, one or more of the described operations can be automatically selected. This method can execute one or more operations to identify a trajectory that allows reaching the command engagement state provided by the user at the user input device. Alternatively, the user can manually activate one or more of these operations. The user can then provide input to advance on the command engagement trajectory while controlling the flexible elongating device using the described trajectory and / or superimposed force / torque / tension modifications until the command engagement state is reached. Thus, these operations support the user by providing assistance without requiring the user to change the input they provide for controlling engagement. While the input is described as user-provided (e.g., provided by the user at the input device), the input can also be provided autonomously or semi-autonomously by the algorithm.

[0100] One or more components of the embodiments discussed in this disclosure (e.g., control system 112) may be implemented in software to execute on one or more processors of a computer system. The software may include code that, when executed by one or more processors, configures the processors to perform the various functions discussed herein. The code may be stored in a non-transitory computer-readable storage medium (e.g., memory, magnetic storage device, optical storage device, solid-state storage device, etc.). The computer-readable storage medium may be part of a computer-readable storage device, such as electronic circuitry, a semiconductor device, a semiconductor memory device, a read-only memory (ROM), flash memory, an erasable programmable read-only memory (EPROM), a floppy disk, a CD-ROM, an optical disk, a hard disk, or other storage device. The code may be downloaded to the computer-readable storage medium for storage via a computer network such as the Internet, an intranet, etc. The code may be executed by any of a variety of centralized or distributed data processing architectures. The programming instructions of the code may be implemented as multiple separate programs or subroutines, or they may be integrated into multiple other aspects of the system described herein. Components of the computing system discussed herein may be connected using wired and / or wireless connections. In some examples, wireless connectivity can use wireless communication protocols such as Bluetooth, Near Field Communication (NFC), Infrared Data Association (IrDA), HomeRF, IEEE 802.11, Digital Enhanced Cordless Telecommunications (DECT), and Wireless Medical Telemetry Service (WMTS).

[0101] Various general-purpose computer systems can be used to perform one or more processes, methods, or functions described herein. Additionally or alternatively, various special-purpose computer systems can be used to perform one or more processes, methods, or functions described herein. Furthermore, various programming languages ​​can be used to implement one or more processes, methods, or functions described herein.

[0102] While certain implementations and examples have been described above and shown in the accompanying drawings, it should be understood that these implementations and examples are merely exemplary and not limited to the specific constructions and arrangements shown and described, as various other alternatives, modifications and equivalents will be understood by those skilled in the art.

[0103] As can be seen from the above description, the embodiments of the present invention also disclose the following technical solutions, including but not limited to:

[0104] Option 1. A medical system comprising:

[0105] A manipulator assembly, comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on changing a plurality of tensions applied to a plurality of traction lines; and

[0106] A control system coupled to the manipulator assembly, the control system being configured to:

[0107] The plurality of actuators are controlled using a control scheme to change the engagement state of the flexible elongation device, the control scheme defining an upper limit tension applied to each of the plurality of traction lines;

[0108] If it is determined that the first actuator among the plurality of actuators does not apply a tension exceeding the upper limit to the first traction line among the plurality of traction lines, the command engagement state of the flexible elongation device cannot be achieved by controlling the first actuator; and

[0109] If the first actuator does not apply tension exceeding the upper limit to the first traction line, the second actuator among the plurality of actuators is controlled to change the amount of tension applied to the second traction line among the plurality of traction lines, thereby achieving the command engagement state.

[0110] Option 2. The medical system according to Option 1, wherein determining that the command engagement state cannot be achieved by controlling the first actuator includes: determining that the actual engagement of the flexible elongation device from the initial engagement state to the command engagement state on the command trajectory is incomplete.

[0111] Option 3. The medical system described in Option 2,

[0112] Determining that the actual engagement of the flexible elongation device on the command trajectory is incomplete includes: determining the position tracking error at the command engagement state.

[0113] Option 4. A medical system according to any one of Options 1 to 3, wherein:

[0114] The first traction line and the second traction line control different engagement shafts;

[0115] When a direct engagement trajectory is used from the initial engagement state to the commanded engagement state, the commanded engagement state cannot be achieved by controlling the first actuator, and

[0116] The second actuator is controlled to use a non-direct engagement trajectory to achieve the command engagement state from the initial engagement state to the command engagement state.

[0117] Option 5. The medical system described in Option 4,

[0118] The non-direct engagement trajectory includes a first segment and a second segment. The first segment diverges from the direct engagement trajectory from the initial engagement state to the command engagement state, and the second segment converges to the direct engagement trajectory.

[0119] Option 6. The medical system according to Option 5, wherein the second segment converges with the direct engagement trajectory at the command engagement state.

[0120] Option 7. The medical system according to Option 5, wherein the non-directly coupled trajectory includes repetition of the first segment and the second segment.

[0121] Option 8. The medical system according to Option 5,

[0122] The indirect bonding trajectory includes a first directional component in the first bonding direction, which is more dominant than the second directional component in the second bonding direction.

[0123] In the first and second segments of the non-directly coupled trajectory, the second directional component increases relative to the first directional component of the command trajectory.

[0124] Option 9. The medical system according to any one of Options 1 to 3, wherein the upper limit tension is the maximum tension.

[0125] Option 10. A medical system according to any one of Options 1 to 3,

[0126] The control scheme defines the minimum tension applied to each of the plurality of traction lines;

[0127] The first traction line and the second traction line control a common joint shaft; and

[0128] The control system is configured to control the second actuator to reduce the tension applied to the second traction line below the minimum tension to achieve the command engagement state.

[0129] Option 11. The medical system according to Option 10,

[0130] Wherein, the minimum tension is reduced to zero.

[0131] Option 12. A medical system according to any one of Options 1 to 3,

[0132] The control scheme dynamically sets the upper limit tension applied to each of the plurality of traction lines to constrain the torque at equal intervals in the engagement space formed by the combination of the first engagement direction and the second engagement direction of the flexible elongation device.

[0133] Option 13. The medical system according to Option 12, wherein the control system is further configured to:

[0134] When the second actuator of the plurality of actuators is controlled to change the amount of tension applied to the second traction line of the plurality of traction lines to achieve the command engagement state without the first actuator applying a tension exceeding the upper limit to the first traction line, the equidistant constraint of the torque is disabled.

[0135] Option 14. The medical system according to Option 13, wherein the upper limit tension is the maximum tension when the equidistant constraint of the torque is disabled.

[0136] Option 15. The medical system according to Option 13, wherein the second actuator is controlled to achieve the command engagement state using a non-direct engagement trajectory from the initial engagement state to the command engagement state.

[0137] Option 16. A non-transitory machine-readable medium comprising a plurality of machine-readable instructions, said plurality of machine-readable instructions being executed by one or more processors associated with a medical system.

[0138] The medical system includes a manipulator assembly comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on varying the tensions of a plurality of traction wires applied to the flexible elongation device.

[0139] The plurality of machine-readable instructions cause the one or more processors to execute a method, the method comprising:

[0140] The plurality of actuators are controlled using a control scheme to change the engagement state of the flexible elongation device, the control scheme defining an upper limit tension applied to each of the plurality of traction lines;

[0141] If it is determined that the first actuator of the plurality of actuators cannot achieve the command engagement state of the flexible elongation device by controlling the first actuator if the first actuator of the plurality of actuators does not apply a tension exceeding the upper limit to the first traction line of the plurality of traction lines; and

[0142] If the first actuator does not apply tension exceeding the upper limit to the first traction line, the second actuator among the plurality of actuators is controlled to change the amount of tension applied to the second traction line among the plurality of traction lines, thereby achieving the command engagement state.

[0143] Option 17. The non-transient machine-readable medium according to Option 16, wherein determining that the command engagement state cannot be achieved by controlling the first actuator includes: determining that the actual engagement of the flexible elongation device from the initial engagement state to the command engagement state on the command trajectory is incomplete.

[0144] Option 18. The non-transitory machine-readable medium according to Option 17,

[0145] Determining that the actual engagement of the flexible elongation device on the command trajectory is incomplete includes: determining the position tracking error at the command engagement state.

[0146] Option 19. A non-transitory machine-readable medium according to any one of Options 16 to 18, wherein:

[0147] The first traction line and the second traction line control different engagement shafts.

[0148] When a direct engagement trajectory is used from the initial engagement state to the commanded engagement state, the commanded engagement state cannot be achieved by controlling the first actuator, and

[0149] The second actuator is controlled to use a non-direct engagement trajectory to achieve the command engagement state from the initial engagement state to the command engagement state.

[0150] Option 20. The non-transitory machine-readable medium according to Option 19,

[0151] The indirect engagement trajectory includes a first segment and a second segment. The first segment diverges from the command trajectory from the initial engagement state to the command engagement state, and the second segment converges to the command trajectory.

[0152] Option 21. The non-transient machine-readable medium according to Option 20, wherein the second segment converges with the command trajectory at the command engagement state.

[0153] Option 22. The non-transient machine-readable medium according to Option 20, wherein the non-directly joined trajectory includes repetition of the first segment and the second segment.

[0154] Option 23. The non-transitory machine-readable medium according to Option 20,

[0155] The command trajectory includes a first directional component in the first engagement direction, which is more dominant than the second directional component in the second engagement direction.

[0156] In the first and second segments of the non-directly coupled trajectory, the second directional component increases relative to the first directional component of the command trajectory.

[0157] Option 24. A non-transient machine-readable medium according to any one of Options 16 to 18, wherein the upper limit tension is the maximum tension.

[0158] Option 25. A non-transitory machine-readable medium according to any one of Options 16 to 18,

[0159] The control scheme defines the minimum tension applied to each of the plurality of traction lines;

[0160] The first traction line and the second traction line control a common joint shaft; and

[0161] The control system is configured to control the second actuator to reduce the tension applied to the second traction line below the minimum tension to achieve the command engagement state.

[0162] Option 26. The non-transitory machine-readable medium according to Option 25,

[0163] The minimum tension is updated to zero.

[0164] Option 27. A non-transitory machine-readable medium according to any one of Options 16 to 18,

[0165] The control scheme dynamically sets the upper limit tension applied to each of the plurality of traction lines to constrain the torque at equal intervals in the engagement space formed by the combination of the first engagement direction and the second engagement direction of the flexible elongation device.

[0166] Option 28. The non-transitory machine-readable medium according to Option 27, wherein the method further comprises:

[0167] When the second actuator of the plurality of actuators is controlled to change the amount of tension applied to the second traction line of the plurality of traction lines to achieve the command engagement state without the first actuator applying a tension exceeding the upper limit to the first traction line, the equidistant constraint of the torque is disabled.

[0168] Option 29. The non-transient machine-readable medium according to Option 28, wherein the upper limit tension is the maximum tension when the equidistant constraint of the torque is disabled.

[0169] Option 30. The non-transient machine-readable medium according to Option 28, wherein the second actuator is controlled to achieve the command engagement state using a non-direct engagement trajectory from the initial engagement state to the command engagement state.

[0170] Option 31. A method for operating a medical system,

[0171] The medical system includes a manipulator assembly comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on changing multiple tensions applied to multiple traction lines of the flexible elongation device.

[0172] The method includes:

[0173] The plurality of actuators are controlled using a control scheme to change the engagement state of the flexible elongation device, the control scheme defining an upper limit tension applied to each of the plurality of traction lines;

[0174] If it is determined that the first actuator of the plurality of actuators cannot achieve the command engagement state of the flexible elongation device by controlling the first actuator if the first actuator of the plurality of actuators does not apply a tension exceeding the upper limit to the first traction line of the plurality of traction lines; and

[0175] If the first actuator does not apply tension exceeding the upper limit to the first traction line, the second actuator among the plurality of actuators is controlled to change the amount of tension applied to the second traction line among the plurality of traction lines, thereby achieving the command engagement state.

[0176] Option 32. A medical system comprising:

[0177] A manipulator assembly, comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on changing a plurality of tensions applied to a plurality of traction lines; and

[0178] A control system coupled to the manipulator assembly is configured to control the plurality of actuators to move the flexible elongation device from a first engagement state to a second engagement state using a non-direct engagement trajectory.

[0179] Option 33. The medical system according to Option 32, wherein the control system, in response to the flexible elongation device being unable to reach the second engagement state from the first engagement state using a direct engagement trajectory, moves the flexible elongation device using the indirect engagement trajectory.

[0180] Option 34. The medical system according to Option 32, wherein the indirect engagement trajectory includes an offset movement along the engagement axis of the flexible elongation device.

[0181] Option 35. The medical system according to Option 32, wherein the indirect engagement trajectory includes a plurality of offset movements along the engagement axis of the flexible elongation device.

[0182] Option 36. A medical system comprising:

[0183] A manipulator assembly, comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on changing a plurality of tensions applied to a plurality of traction lines; and

[0184] A control system coupled to the manipulator assembly is configured to control the plurality of actuators to move the flexible elongation device using equidistant constraints, and to disable the equidistant constraints in response to the flexible elongation device being unable to move from a first engagement state to a second engagement state with the equidistant constraints.

Claims

1. A medical system comprising: A manipulator assembly comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on changing a plurality of tensions applied to a plurality of traction lines of the flexible elongation device. as well as A control system coupled to the manipulator assembly, the control system being configured to: The plurality of actuators are controlled using a control scheme to change the engagement state of the flexible elongation device, the control scheme defining an upper limit tension applied to each of the plurality of traction lines; If it is determined that the first actuator among the plurality of actuators does not apply a tension exceeding the upper limit to the first traction line among the plurality of traction lines, the command engagement state of the flexible elongation device cannot be achieved by controlling the first actuator; as well as If the first actuator does not apply tension exceeding the upper limit to the first traction line, the second actuator among the plurality of actuators is controlled to change the amount of tension applied to the second traction line among the plurality of traction lines, thereby achieving the command engagement state.

2. The medical system according to claim 1, wherein, Determining that the command engagement state cannot be achieved by controlling the first actuator includes: determining that the actual engagement of the flexible elongation device from the initial engagement state to the command engagement state on the command trajectory is incomplete.

3. The medical system according to claim 2, in, Determining that the actual engagement of the flexible elongation device on the command trajectory is incomplete includes: determining the position tracking error at the command engagement state.

4. The medical system according to any one of claims 1 to 3, wherein: The first traction line and the second traction line control different engagement shafts; When a direct engagement trajectory is used from the initial engagement state to the commanded engagement state, the commanded engagement state cannot be achieved by controlling the first actuator, and The second actuator is controlled to use a non-direct engagement trajectory to achieve the command engagement state from the initial engagement state to the command engagement state.

5. The medical system according to claim 4, in, The indirect engagement trajectory includes a first segment and a second segment, wherein the first segment diverges from the direct engagement trajectory from the initial engagement state to the command engagement state, and the second segment converges to the direct engagement trajectory.

6. The medical system according to claim 5, wherein, The second segment converges with the direct engagement trajectory at the command engagement state.

7. A non-transitory machine-readable medium comprising a plurality of machine-readable instructions, said plurality of machine-readable instructions being executed by one or more processors associated with a medical system. The medical system includes a manipulator assembly comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on changing multiple tensions applied to multiple traction lines of the flexible elongation device. The plurality of machine-readable instructions cause the one or more processors to execute a method, the method comprising: The plurality of actuators are controlled using a control scheme to change the engagement state of the flexible elongation device, the control scheme defining an upper limit tension applied to each of the plurality of traction lines; If it is determined that the first actuator of the plurality of actuators does not apply a tension exceeding the upper limit to the first traction line of the plurality of traction lines, the command engagement state of the flexible elongation device cannot be achieved by controlling the first actuator; as well as If the first actuator does not apply tension exceeding the upper limit to the first traction line, the second actuator among the plurality of actuators is controlled to change the amount of tension applied to the second traction line among the plurality of traction lines, thereby achieving the command engagement state.

8. A method for operating a medical system, The medical system includes a manipulator assembly comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on changing multiple tensions applied to multiple traction lines of the flexible elongation device. The method includes: The plurality of actuators are controlled using a control scheme to change the engagement state of the flexible elongation device, the control scheme defining an upper limit tension applied to each of the plurality of traction lines; If it is determined that the first actuator of the plurality of actuators does not apply a tension exceeding the upper limit to the first traction line of the plurality of traction lines, the command engagement state of the flexible elongation device cannot be achieved by controlling the first actuator; as well as If the first actuator does not apply tension exceeding the upper limit to the first traction line, the second actuator among the plurality of actuators is controlled to change the amount of tension applied to the second traction line among the plurality of traction lines, thereby achieving the command engagement state.

9. A medical system comprising: A manipulator assembly comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on changing a plurality of tensions applied to a plurality of traction lines of the flexible elongation device. as well as A control system coupled to the manipulator assembly is configured to control the plurality of actuators to move the flexible elongation device from a first engagement state to a second engagement state using a non-direct engagement trajectory.

10. A medical system comprising: A manipulator assembly comprising a plurality of actuators configured to control the engagement state of the flexible elongation device based on changing a plurality of tensions applied to a plurality of traction lines of the flexible elongation device. as well as A control system coupled to the manipulator assembly is configured to control the plurality of actuators to move the flexible elongation device using equidistant constraints, and to disable the equidistant constraints in response to the flexible elongation device being unable to move from a first engagement state to a second engagement state with the equidistant constraints.

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