SYSTEM AND METHOD FOR UNDERACTUATED CONTROL OF INSERTION PATH FOR ASYMMETRIC TIP NEEDLES
A needle steering system and apparatus provides active, semi-autonomous control of needle insertion paths while still enabling a clinician ultimate control over needle insertion. A method and system controls the needle path as the needle is inserted by precisely controlling the rotation of the needle as it continuously rotates during insertion. This enables underactuated 2 degree-of-freedom (DOF) control of the direction and the curvature of the needle from a single rotary actuator. Control of the rotary motion is therefore decoupled from the needle insertion. The rotary motion controls steering effort and direction, while the insertion controls needle depth or insertion speed. In one implementation, the proposed method does not require constant velocity insertion, interleaved insertion and rotation, or known insertion position or speed. The insertion may be provided by a robot or other automated method, may be a manual insertion, or may be a teleoperated insertion.
This application is a continuation of U.S. patent application Ser. No. 16/107,184 filed Aug. 21, 2018, which is a divisional of U.S. patent application Ser. No. 14/056,205, filed Oct. 17, 2013, which claims the benefit of U.S. Provisional Application No. 61/715,063, filed Oct. 17, 2012, the contents of all of which are incorporated herein by reference.
FIELD OF INVENTIONThe disclosed configuration relates to a system and approach for controlling insertion paths of needles with asymmetric tips for therapeutic and diagnostic medical interventions, and especially underactuated control of needle curvature and direction decoupled from needle insertion.
BACKGROUNDNeedle-based interventions are commonplace. These may be used for a variety of percutaneous diagnostic and therapeutic interventions. However, ensuring that the needle, cannula, or other instrument makes it to the desired target while following a desired path is often nontrivial. Inaccuracy may come from various causes including needle deflection, tissue deformation, target motion, patient motion, or other sources. Many needles have asymmetric tip shapes, such as a beveled tip and/or cannula. In some cases, these tips cause asymmetric forces on the needle that cause it to deflect as it is inserted. This deflection in many cases is undesirable and results in errors in needle placement. However, some clinicians use the asymmetric tip forces to their advantage and actively control or steer the needle path during insertion by rotating the bevel direction. Further, others have attempted continuous rotation or drilling of a needle to ensure that it follows a straight insertion path.
SUMMARYThe present disclosure teaches active, semi-autonomous control of needle insertion paths while still enabling a clinician ultimate control over needle insertion. The present teaching describes a method and system for controlling needle path as the needle is inserted by precisely controlling the rotation of the needle as it continuously rotates during insertion. This enables underactuated 2 degree-of-freedom (DOF) control of the direction and the curvature of the needle from a single rotary actuator. An advantage of the disclosed configuration is that control of the rotary motion may be decoupled from the needle insertion. The rotary motion controls steering effort and direction, while the insertion controls needle depth or insertion speed. In one implementation, the proposed method does not require constant velocity insertion, interleaved insertion and rotation, or known insertion position or speed. The insertion may be provided by a robot or other automated method, may be a manual insertion, or may be a teleoperated insertion.
Control of the needle path may be used in multiple cases. In one case, as the needle is inserted an error is determined between the projection of the needle and the target, so a compensation in the needle path is required. In other cases, a specific path or trajectory is desired, and the needle is controlled along that path to reach the target. In a combined case, a predetermined path is defined, and compensation is required as the needle is inserted to ensure the path is followed and the endpoint reached. These control approaches may be open loop or closed loop. The closed loop approach may be based upon medical imaging or image-guidance such as ultrasound, x-ray, fluoroscopy, computed tomography (CT), magnetic resonance imaging (MRI), video feeds, laser scans, external tracking systems, or other approaches.
The present teaching relates generally to controlling the trajectory of a needle or other instrument with an asymmetric tip. The disclosed arrangement describes a method for underactuated control of needle direction and curvature as it is inserted into tissue that is decoupled from the needle insertion motion. The approach also describes a system and components for implementing the proposed method.
In a particular configuration, the disclosed approach employs a method for inserting a needle with a asymmetric shaped tip into tissue along a curved path, wherein the needle is continuously rotated at a time-varying angular velocity; wherein the time-varying angular velocity rotation is a function of the needle angular position.
An example needle steering apparatus suitable for use with configurations herein includes a needle having an asymmetric tip, the asymmetric tip defined by a beveled cut across a cylindrical cross section of the needle, and a rotary drive for rotating the needle along a needle axis. The rotary drive is responsive to control logic adapted to rotate the needle at an angular velocity based on an angular position, and invokes an inserter for disposing the needle axially in a direction of an axis of rotation, such that the angular velocity is independent from the insertion.
In operation, in a surgical environment having an asymmetric tipped needle and a needle driving apparatus responsive to rotational and insertion control, the method of directing the needle includes identifying a steering trajectory path for the needle, and controlling a time-varying rotation speed of the needle based on the identified steering path, such that the rotation speed determines a relative duration that a bevel angle of the needle applies force in a direction corresponding to the steering trajectory. The rotation is decoupled from advancement of the needle resulting from control of the controlled rotation speed about the needle axis, such that the controlled rotation speed is based on an angle of rotation, and independent of the linear advancement of the needle from the insertion control, so that the needle follows the prescribed path regardless of the insertion speed.
The foregoing and other objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
Configurations disclosed below teach a mechanism referred to as the Continuous Uncoupled Rotation Velocity-independent (CURV) steering approach. The described approach is one example, however the disclosed configuration also includes other related variants of decoupled, underactuated control of needle insertion based on asymmetric tips. The disclosed configuration also describes a plethora of systems and components for implementing the proposed approach. In one embodiment, a robotic needle driver provides 2 DOF control of needle rotation and insertion, thus providing 3 DOF control of the tip (i.e. can place the tip to a 3D position using 2 actuators). The needle driver may further be configured as part of a robotic system. The system may further be configured to incorporate a teleoperation master that a user manipulates to control needle insertion and/or steering angle. The configuration may further include force sensing and haptic feedback. The haptic feedback may be related to the forces on the needle, errors determined by a control system, external factors, or some combination of factors. In one configuration, a user manipulates the teleoperation master along only the insertion axis to control the insertion depth, while the robot automatically steers the needle path according to the disclosed configuration. This may be used based on preoperative path planning, or actively and semi-autonomously compensating for errors as the needle is inserted. In a further embodiment, the rotation is manipulated according to the disclosed configuration by an actuator in a standalone device, and in particular configurations the device may be handheld. The device can control steering effort (related to needle curvature in tissue during insertion) and in alternate configurations may also control angle and/or depth relative to the handle. In an additional embodiment of the disclosed approach, the asymmetric tip control methods taught in the disclosed configuration may be coupled with concentric precurved or prebent tubes or cannulas to provide additional dexterity and control during needle insertion.
Additional advantages of the disclosed configuration will become readily apparent to those skilled in this art from the following detailed description, wherein only selected embodiments of the disclosed configuration are shown and described. As will be realized, the disclosed configuration is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention disclosed herein. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
The present teachings are described more fully hereinafter with reference to the accompanying drawings, in which the present embodiments are shown. The following description is presented for illustrative purposes only and the presented teachings should not be limited to these embodiments.
In this disclosure, the term “needle” is defined as cylindrical instrument that interacts with tissues, including but not limited to medical needles, electrodes, tubes, rods, and cannulae. The term needle axis refers to the axis along the needle, or subsection thereof. The needles can typically be inserted and rotated along and about thus axis, respectively. In some cases torsional affects make the rotation at various points along the needle unequal, and this can be compensated for if necessary to control the desired subsection of the needle, such as the tip form the base. The term asymmetric tip generally refers to a bevel-shaped tip on a needle, however more broadly it is defined as any feature on a needle that provide asymmetric forces that alter the insertion path as it is inserted.
The examples and discussion that follows employ a surgical context as an example implementation, such that the a surgical needle or cannulated instrument adapted for surgical use is a steerable member, and a medium employed for drilling is surgical tissue. Alternate configurations may employ alternate arrangements of a steerable member and a medium. For example, geological applications may employ steering for exploration of geological structures, such as rock and soil. Alternate configurations may also be employed for building materials such as concrete or wood, or other medium responsive to the steering methodology disclosed herein.
In one embodiment of the disclosed configuration, the needle path direction and curvature is controlled using the approach detailed below and shown in
In one approach, the normalized angular velocity of the needle about its primary axis is defined using the Gaussian distribution as:
(9−0)2′
6(9,Od)=1−Cre2c2
-
- eb(0,0d): normalized needle rotation angular velocity about its primary axis
- 8: current needle angle about its primary axis
- Od: needle rotation angle corresponding to desired steering direction
- a: steering effort where 1 is maximum steering curvature and 0 is a straight path
- c: tuning parameter related to width of the distribution about 8d
The equation above describes the use of a normal, Gaussian distribution to determine the angular velocity, a), of the needle about its primary axis as a function of the difference between current needle angle, 8, and desired direction, Od, and is shown representatively in
The calculation is performed continuously as the needle rotates to determine the corresponding angular velocity or angle set point.
In one embodiment, needle steering is implemented in software on a control system where the normalized needle rotation angular velocity is calculated in a control loop running at a fixed timer period such as a servo loop running at 1 kHz. The angular velocity of the needle about its primary axis as a function of current angle as it rotates is calculated as:
e)(6)=comax6
-
- 9(9): needle rotation angular velocity about its primary axis
- a): normalized needle rotation angular velocity about its primary axis
- co.: maximum angular velocity of needle about its primary axis
In one implementation, a discrete time controller is used to determine an angle set point for the next period based on the desired angular velocity as:
9(t±1)=9(t)amaxcZT
-
- 9(t+1): needle rotation angle set point for next period
- 9(t): needle rotation angle in current period
- Co: normalized needle rotation angular velocity about its primary axis
- co.: maximum angular velocity of needle about its primary axis
- T: time period between cycles of control loop
This disclosure refers to the term steering effort which is directly related to curvature, wherein full steering effort corresponds to the maximum curvature and zero steering effort corresponds to a straight insertion with no curvature. In closed loop control, steering effort is used within the control loop to correct a needle insertion path based on a detected error.
The specific curvature for a given steering effort is also related to needle properties, tissue properties, and external forces. The steering effort may be run open loop to drive the needle along a specific path, it may be controlled in a closed loop to follow a specific path, or it may be used as a control input to steer the needle towards the target, much like a steering wheel on a car.
In
The insertion is decoupled from the insertion speed, this the overall needle shape at the end of insertion is essentially the same independent of insertion speed. The size of the helical path around that needle shape varies as a function of the relative insertion and rotation speed. For a high rotation speed or low insertion speed, the needle tip path essentially matches the final needle shape after insertion (i.e. negligible helical tip motion).
In one configuration, the handheld device contains a motor, angular position sensor, steering effort control switch, processor, and battery. The device may be fully self contained and steers the needle with a curvature related to the steering effort input. The user may use this with independently obtained interactively updated or real-time imaging. The device may also incorporate a biopsy sample retrieval mechanism. An embodiment of the device may be single use or limited lifetime. This configuration may be used for percutaneous procedures or other access to internal tissues. It may also be used for accessing structures close to the surface such as cannulation of blood vessels, acupuncture, or other medical procedures. In one embodiment, the device is fully compatible with the MRI environment and may be used during MR imaging without significantly degrading image quality.
In this embodiment, a collect 116 holds the asymmetric needle 110 and enables control of rotation about the needle axis 112 and insertion translation. The drive 120 includes a rotary motor 232 for providing the drive 120. A piezoelectric motor 233 or other suitable drive provides a separate rotation source for a cannula 113, augmented by one or more pulleys 230 and belts 234 for controlling rotation of the cannula 113 and/or needle 110 inserted therethrough, as is known with surgical cannulas. The drive 120 may be further facilitated by an eccentric belt tensioner 236, bearings 238, and a linear optical encoder 240 for measuring translation 130 feedback of needle insertion, and a rotary optical encoder 242 for needle rotation angle feedback.
A further embodiment of a needle driver is depicted in
In alternate configurations, a slave robot is actuated using piezoelectric motors and incorporates FPI fiberoptic force sensing. The slave robot has a needle rotation module capable of using the proposed steering approach. The master device measures needle translation that controls slave needle insertion depth and optionally rotation that may be used to control steering angle either directly or through the proposed steering approach. In a further configuration, force feedback may be provided on the haptic mater device using pneumatics or other actuation technologies. A configuration of the system uses hybrid actuation with pneumatic control of the master robot and piezoelectric actuation of the slave robot. One embodiment of the system is MRI-compatible to enable the controller, master, and slave to reside inside an MRI scanner room and be used during imaging without significantly degrading image quality.
In another arrangement, the apparatus and methods disclosed above may be integrated into a system configuration for teleoperated control of the needle inside the MRI scanner. In one configuration, the target is tracked in interactively updated MRI images. The user control insertion depth of the needle held by the slave robot using the master robot device. The user can visualize the insertion progress in interactively updated MR images. In one configuration, the needle may be autonomously steered to reach the target, while the user only directly controls insertion depth or insertion speed. In this configuration, the target and needle are tracked in interactively updated medical images, and the control system uses the teachings of the resent invention to steer the needle to the target (i.e. active compensation of the path) while the user (e.g. a clinician) controls the insertion depth or insertion speed using a master device while visualizing the needle insertion. This enables the clinician control over depth, thus potentially improving safety over a fully autonomous system, while enable the control system to ensure the needle reaches the target even in the presence of deformation. In an alternate configuration, the needle driver robot is not actuated along needle insertion (only position sensing along the insertion direction), and the user directly inserts the needle by pushing on the needle driver (without a separate teleoperation master) while the rotation module autonomously steers the needle according to the teachings of the disclosed configuration.
The above description provides detail about exemplary configurations and algorithms of the disclosed configuration's teachings; however, the disclosed configuration is not restricted to only the specific configuration or approaches shown.
The present configurations may be practiced by employing conventional materials, methodology and equipment. Accordingly, the details of such materials, equipment and methodology are not set forth herein in detail. In the previous descriptions, numerous specific details are set forth, such as specific materials, structures, processes, etc., in order to provide a thorough understanding of the disclosed configuration. However, it should be recognized that the disclosed configuration can be practiced without resorting to the details specifically set forth. Only an exemplary embodiment of the disclosed configuration and but a few examples of its versatility are shown and described in the present disclosure. It is to be understood that the disclosed configuration is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.
Those skilled in the art should readily appreciate that the programs and methods defined herein are deliverable to a user processing and rendering device in many forms, including but not limited to a) information permanently stored on non-writeable storage media such as ROM devices, b) information alterably stored on writeable non-transitory storage media such as floppy disks, magnetic tapes, CDs, RAM devices, and other magnetic and optical media, or c) information conveyed to a computer through communication media, as in an electronic network such as the Internet or telephone modem lines. The operations and methods may be implemented in a software executable object or as a set of encoded instructions for execution by a processor responsive to the instructions. Alternatively, the operations and methods disclosed herein may be embodied in whole or in part using hardware components, such as Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), microcontrollers, state machines, controllers or other hardware components or devices, or a combination of hardware, software, and firmware components.
While the system and methods defined herein have been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
Claims
1. In a surgical environment having an asymmetric tipped needle and a needle driving apparatus responsive to rotational control, a method of directing the needle comprising: identifying a steering path for the needle;
- controlling a time-varying rotation speed of the needle based on the identified steering path, the rotation speed determining a relative duration that a bevel angle of the needle applies force in a direction corresponding to the steering trajectory; and
- decoupling advancement of the needle from control of the rotation speed about the needle axis, such that the controlled rotation speed is based on an angle of rotation independent of advancement of the needle.
2. The method of claim 1 further comprising defining an asymmetric tip from a bevel cut across at least a portion of a cylindrical needle, the bevel cut forming an angle and a bevel face on the needle tip.
3. The method of claim 1 wherein decoupling further comprises decoupling the rotation speed from the linear advancement by underactuated control of the needle such that curvature and direction of an insertion path is controlled based on determining the angular velocity as a function of the rotation angle as the needle rotates continuously.
4. The method of claim 1 further comprising:
- inserting the asymmetric tip into a tissue medium, the medium exerting a normal force on the asymmetric tip resulting from a beveled angle on the asymmetric tip; and
- controlling the rotation speed based on a rotational position of the asymmetric tip such that the rotation speed disposes the bevel face against the medium for directing the needle in the direction corresponding to the steering path.
5. The method of claim 4 wherein the controlled rotation speed disposes the bevel face for a longer time in a direction corresponding to the desired steering direction, the bevel angle providing a steering force against the medium.
6. The method of claim 1 wherein controlling the rotation speed includes varying the rotation speed such that the rotation speed defines a relative duration that a bevel face of the asymmetric tip applies steering force in a particular direction, wherein an extent of curvature and the direction angle of the needle are controlled via a single actuator.
7. The method of claim 1 further comprising:
- defining a complex path for the needle by aggregating a plurality of curved steering paths, each steering path defined by an arc, direction, and distance.
8. The method of claim 7, further employing a closed loop monitoring to maintain rotational control for each of the plurality of steering paths along the complex path or to reach the predetermined target location.
9. The method of claim 1 further comprising:
- controlling needle advancement based on a signal received from a manually actuated user interface unit; and
- controlling needle rotation based on angular position and the steering path, the needle rotation independent of the manual actuation signal.
10. The method of claim 4 further comprising:
- identifying angular rotation by receiving signals from an optical encoder attached to the needle; and
- adjusting the rotation speed based on the received signals.
11. The method of claim 4 further comprising:
- identifying insertion depth by receiving signals from an optical encoder attached to the needle; and updating the desired path based on the insertion depth.
12. The method of claim 3 further comprising:
- sensing forces exerted on the needle by the tissue medium; and
- providing haptic feedback based on the sensed forces to an operator.
13. The method of claim 1 further comprising disposing the needle using a 2 degree-of-freedom (DOF) drive for controlling rotation and insertion for providing a 3 DOF targeting ability for steering the needle to a target.
14. The method of claim 1, wherein the needle driving apparatus is underactuated and capable of controlling needle direction angle, curvature, and insertion depth from two actuators.
15. The method of claim 14, wherein control of needle direction angle and needle curvature is decoupled from control of needle insertion depth, wherein it is not required to coordinate needle insertion motion with needle rotation motion.
16. A method for inserting a needle with an asymmetric shaped tip into tissue along a curved path, wherein the needle is continuously rotated at a time-varying angular velocity;
- wherein the time-varying angular velocity rotation is a function of the needle angular position.
17. The method of claim 23, wherein the time-varying angular velocity of the needle is controlled such that one actuator provides for control of both needle curvature and needle direction angle.
18. The method of claim 24, wherein control of the rotation of the needle is decoupled from control of the needle insertion motion along the length of the needle.
19. The method of claim 24, wherein needle curvature and needle insertion direction are controlled independently from needle insertion.
20. The method of claim 26, wherein needle insertion is manually controlled by a user.
21. The method of claim 27, wherein needle depth is controlled through a teleoperation interface and needle curvature and direction are controlled automatically.
22. The method of claim 28, further comprising incorporation of haptic feedback to the user through the teleoperation interface to reflect needle insertion forces or other feedback relating to the needle insertion process.
23. The method of claim 23 wherein a user controls needle insertion depth, wherein an automatic control system controls needle direction and curvature to maintain a path to a target location.
24. The method of claim 23, wherein an automatic control system directs two actuators based on closed loop imaging feedback; further comprising a first actuator for control of needle insertion depth; and a second actuator for needle direction and curvature; wherein the automatic control system directs the needle to maintain a path to a target location.
25. The method of claim 23 further comprising manual control of the needle insertion through the use of a handheld instrument.
26. The method of claim 32, wherein the handheld instrument controls continuous needle rotation and a user manually controls needle insertion.
27. The method of claim 31, wherein the automatic control system manages the needle trajectory based on imaging feedback to provide closed loop control of the needle trajectory to reach a target.
28. The method of claim 24, wherein the needle with asymmetric shaped tip is inserted through one or more precurved concentric tubes, wherein the precurved concentric tubes provide initial guidance of the needle trajectory and the needle with asymmetric shaped tip is controlled for precision placement of the needle tip as the needle approaches a target location.
Type: Application
Filed: Dec 27, 2021
Publication Date: Sep 8, 2022
Inventors: Gregory S. Fischer (Boston, MA), Hao Su (Somerville, MA)
Application Number: 17/562,785