Vascular access simulation system with receiver for an end effector

The illustrative embodiment is a simulation system for practicing vascular-access procedures without using human subjects. The simulator includes a data-processing system and a haptics interface device. The haptics device provides the physical interface at which an end effector (e.g., medical instrument, such as a needle, catheter, etc.) is manipulated to simulate needle insertion, etc. In accordance with the illustrative embodiment, the haptics device includes a receiver. The receiver receives the end effector when it's inserted by a user into the haptics device. Sensors that are associated with the receiver monitor the motion and position of the end effector, generate signals indicative thereof, and transmit the signals to the data processing system. The signals are processed to determine the effects of manipulation of the end effector. In some embodiments, the signals are processed to determine the various resistive forces that would arise if the user were manipulating a needle/catheter through actual human anatomy. Responsive to this determination, the receiver generates forces that the user experiences as a resistance to continued advance (insertion) of the end effector. Simulated results are displayed by the computer system.

FIELD OF THE INVENTION

The present invention relates generally to systems that simulate medical procedures for the purposes of training or accreditation. More particularly, the present invention relates to a system, apparatus and subsystems for simulating vascular-access procedures.

BACKGROUND OF THE INVENTION

Medical practitioners, such as military medics, civilian emergency-medical personnel, nurses, and physicians, routinely perform vascular-access procedures (e.g., IV insertion, central venous-line placement, peripherally-inserted central catheter, etc). It is desirable for a practitioner to be proficient at performing these procedures since the proficient practitioner is far less likely to injure a patient and is almost certain to reduce the patient's level of discomfort.

Becoming proficient in vascular-access procedures requires practice. In fact, the certification and re-certification requirements of some states mandate a minimal number of needle sticks, etc., per year per provider. Historically, medical practitioners practiced needle-based procedures on live volunteers. More recently, simulation techniques and devices have been developed to provide training in vascular-access procedures without the use of live volunteers. U.S. Pat. No. 6,470,302 (“the '302 patent”) surveys the art of medical-simulation devices and also discloses a vascular-access simulation system.

The vascular-access simulation system that is disclosed in the '302 patent includes an “interface” device and a computer system. To practice a vascular-access procedure, a user manipulates an “instrument,” referred to in the patent as a “catheter unit assembly,” which extends from the device and serves as a catheter-needle. Potentiometers and encoders within the interface device track the motion and position of the instrument and relay this information to the computer system. The computer system performs a simulation of the surface and subsurface anatomy of human skin, and determines the effect of the instrument's motion on the skin's anatomy. Simulated results are displayed by the computer system. Using the motion information from the interface device, the computer system also generates a control signal that controls a force-feedback system that is coupled to the instrument. The force-feedback system generates various resistive or reactive forces that are intended to simulate the forces that are experienced by a medical practitioner during an actual vascular-access procedure. The user senses these forces during manipulation of the instrument.

The simulation system that is disclosed in the '302 patent has many shortcomings that substantially limit its utility as a training or accreditation tool. A few of these shortcomings are discussed below.

One shortcoming of that simulation system is that forces that are sensed by a user during manipulation of the catheter unit assembly are generally unrealistic. There are several reasons for this. One reason is that the linear axis along which the catheter unit assembly moves is offset from the rotational axes of a sensing/force-feedback assembly to which it's coupled. This results in an unrealistic torque sensation about the “insertion point” of the catheter unit assembly. A second reason for the unrealistic forces and force sensations that are experienced by a user is excessive friction. Specifically, the various tension members and bearings that couple the catheter unit assembly to the sensing/force-feedback assembly introduce a substantial amount of dynamic and static friction to the system. This is problematic because the interface device cannot present a force that is less than the friction that is inherent in the system. This excessive friction therefore limits the dynamic range of the system. Also, the presence of static friction (i.e., stiction) in the device hampers smooth motion of the catheter unit assembly. Stiction is not experienced during an actual vascular-access procedure.

A third reason for the unrealistic forces that are experienced during use of the device that is disclosed in the '302 patent is that the device has relatively high inertia. In particular, the large catheter unit assembly and the offset pulley used in the force-feedback mechanism introduce substantial mass into the system. This is undesirable because the catheter unit assembly will not feel as “light” as it should when little or no force feedback is being applied.

A second shortcoming of the '302 is that the end effector (i.e., the catheter unit assembly) is permanently coupled to the force-feedback system. Although not atypical for this type of system (i.e., haptics devices) due to the difficulty of de-coupling an end effector from its force-feedback system, this is very undesirable because to truly mimic most “actual” systems, de-coupling is necessary.

For example, in the case of an actual vascular-access procedure, a medical practitioner experiences “force-feedback” during insertion of a needle or catheter (i.e., an end effector) into a patient's arm. That is, the anatomy of the arm presents a resistance that is sensed (feedback) by the practitioner. In the actual procedure, the needle or catheter is not, of course, “coupled” to the arm until it is inserted by the practitioner. But in the system that is disclosed in the '302 patent, the catheter unit assembly is coupled to the force-feedback system and extends from interface device at all times. A user, therefore, does not actually insert the catheter unit assembly (i.e., the end effector); there is no coupling and de-coupling.

The inability of prior-art vascular-access simulation systems to realistically simulate a vascular-access procedure limits their usefulness as a training or accreditation tool.

SUMMARY

The illustrative embodiment of the present invention is a simulation system that provides realistic training and practice for performing vascular-access procedures without using human subjects. Unlike most prior-art simulation systems, some embodiments of the present system provide a realistic simulation of the resistive forces that a medical practitioner would experience if the simulated procedure were an actual procedure that was being performed on a real anatomy (e.g., human arm, etc.). Furthermore, in accordance with the illustrative embodiment of the present invention, the end effector (e.g., medical instrument, such as a needle, catheter, etc.) is not coupled to a force-feedback system until a user does so.

The illustrative embodiment of a vascular-access simulator includes a data-processing system and an interface device, referred to herein as a “haptics device.” The haptics device provides the physical interface for performing vascular-access procedures. More particularly, a user inserts an end effector into the haptics device and manipulates it to simulate needle insertion, cannulation, etc. In some embodiments, the simulator is capable of sensing the orientation of the end effector. For example, in some embodiments in which the end effector is a needle or catheter or both, the simulator is capable of sensing the orientation of a beveled end of the needle or catheter.

In accordance with the illustrative embodiment, the haptics device includes a receiver that receives the end effector when it is inserted into the haptics device. In some embodiments in which the end effector is a needle-catheter module, the receiver is a needle-stick module.

In some embodiments, the needle-stick module provides one linear degree of freedom and two, independent, rotational degrees of freedom (i.e., pitch and yaw). In the illustrative embodiment, the linear degree of freedom enables a user to advance the needle/catheter module into the haptics device. This mimics the insertion of a needle/catheter into a patient's arm. The rotational degrees of freedom enable a user to move an engaged needle/catheter module up or down and left or right. This mimics the freedom of movement that a user has during an actual vascular-access procedure.

Sensors within the haptics device monitor the motion and position of the needle/catheter module (e.g., by measuring the insertion depth and pitch and yaw angles of the needle-stick module, etc.). The sensors generate signals indicative of the monitored activity and transmit the signals to the data processing system.

The data processing system processes the information acquired by the sensors and, in conjunction with an anatomical model, determines the effects (e.g., deformation, entry into a vein, etc.) of a user's manipulation of the needle/catheter module on the surface and subsurface features of the virtual body part on which the simulated vascular-access procedure is being performed. Results are displayed by the computer system. The results include, for example, a three-dimensional rendering of the body part of interest, a visual indication of the position of the needle/catheter relative to the body part, and a visual indication of how the needle/catheter affects that body part.

Furthermore, in some embodiments, using the anatomical model and the information obtained from the sensors, the data processing system determines the various resistive forces that would arise if the user were manipulating a needle or catheter through an actual anatomy (e.g., human arm, etc.). Based on this determination, the data processing system or an associated device generates a control signal.

The control signal is ultimately received by the needle-stick module and, responsive thereto, the needle-stick module provides “force feedback” to a user. The force-feedback is sensed by a user as a resistance to continued advance (insertion) of the needle/catheter module. The resistance is intended to simulate penetration or contact with various surface and subsurface features of human anatomy (e.g., the skin, a vein, harder structures such as ligaments, bones, etc.) The resistance advantageously varies with insertion depth and the pitch and yaw of the needle/catheter module (since the resistance is determined based on the estimated position of needle/catheter module in a portion of the human anatomy).

As previously mentioned, it is typical, although undesirable, for an end effector to be permanently coupled to a force-feedback system. In accordance with the illustrative embodiment of the present invention, the needle/catheter module (i.e., an end effector) is not coupled to the needle-stick module (which includes a force-feedback assembly) until a user couples them during a simulated vascular-access procedure. And when the simulated procedure is over, the user decouples the needle/catheter module from the needle-stick module. A user's interactions with simulators described herein therefore more closely simulate a real vascular-access procedure than simulators in the prior art. This more realistic simulation is expected to result in a more useful training experience.

DETAILED DESCRIPTION

The terms and phrases listed below are defined for use in this specification as follows:

“End Effector” means a device, tool or instrument for performing a task. The structure of an end effector depends on the intended task. For example, in the illustrative embodiment, the end effector is intended to be used to simulate a vascular access procedure, and is therefore implemented as a catheter-needle module. Those skilled in the art will recognize that term “end effector” is borrowed from robotics, where it has a somewhat different definition: a device or tool connected to the end of a robot arm.

“Imitation” means an artificial likeness that is intended to be substantially similar to an item being imitated; a copy. For example, “imitation skin,” which is used in conjunction with the illustrative embodiment of the present invention, is intended to mimic or copy genuine skin via appropriate selection of color, appearance, feel, and overall presentation.

“Mock” means “representative;” a stand-in for a genuine article, but not intended to closely imitate the genuine article. A mock article will never be confused with the genuine article and typically does not promote a suspension of disbelief that the mock article is the genuine article. For example, “mock skin” is not intended to mimic genuine skin, and typically departs from it in terms of color, appearance, feel or overall presentation.

“Pseudo” is an inclusive term that means “imitation” or “mock.” For example, pseudo skin is meant to encompass both imitation skin and mock skin.

Additional definitions are provided later in this Detailed Description.

This Detailed Description continues with an overview of a vascular-access simulator in accordance with the illustrative embodiment. Following the overview, specific embodiments of several elements of the simulator are described in greater detail.

Overview

The illustrative embodiment of the present invention pertains to a simulation system that provides realistic training and practice for vascular-access procedures without using human subjects. As depicted inFIG. 1, vascular-access simulator100includes haptics device102and data-processing system104.

Haptics device102provides the physical interface for performing any of several simulated vascular-access procedures (e.g., intravenous catherization, central venous-line placement, sternal intraosseous insertion, etc.).

The term “haptics” (as in “haptics device102”) relates to touch (i.e., the sense of touch). A fundamental function of haptics device102, and indeed any haptics interface, is to create a means for communication between users (i.e., humans) and machines. This “communication” is possible since humans are capable of “mechanically” interfacing with their surroundings due, at least in part, to a sense of touch. This “sense of touch” includes sensations of pressure, texture, puncture, thermal properties, softness, wetness, friction-induced phenomena, adhesions, etc. Furthermore, humans also experience vibro-tactile sensations, which include the perception of oscillating objects in contact with the skin and kinesthetic perceptions (i.e., awareness of one's body state, including position, velocity, and forces supplied by the muscles). As will become clear later in this Detailed Description, our ability to perceive a variety of these sensations is exploited by haptics device102.

To the extent that some embodiments of simulator100are intended for use as a practice and training tool, it is advantageous for haptics device102to simulate vascular-access procedures as realistically as possible and provide a quantitative measure of the user's performance of the simulated procedure. To this end, haptics device102possesses one or more of the following attributes, in addition to any others:It possesses sufficient degrees-of-freedom to simulate the relatively free movement of a needle/catheter during an actual vascular-access procedure.It offers the opportunity to perform all steps of a vascular-access procedure, including, for example, needle insertion, skin interactions (e.g., palpation, skin stretch, etc.), catheter threading, etc.It generates appropriate skin- and venous-puncture forces.It measures or otherwise quantifies the effects of user actions on simulated anatomy.It generates appropriate haptic feedback (i.e., feel) during skin-interaction steps.It is configured to provide ergonomically-correct hand position during simulated vascular-access procedures.It is small enough so that it can be positioned in front of a computer monitor so that the haptics device and the monitor are inline with a user's forward-looking field of view.It is at least subtly suggestive of human anatomy and does not present any substantial departures therefrom so as to support a user's ability to suspend disbelief during a simulated vascular-access procedure.

Data-processing system104, which includes processor106, monitor108, keyboard110, mouse112, and speakers114, supports the visual aspects of the simulation and other functions described below. Processor106is a general-purpose processor that is capable of receiving and processing signals from haptics device102, running software for the visual portion of the vascular-access simulation including an anatomy simulator, running calibration software for calibrating the various sensing elements used in haptics device102, and sending control signals to haptics device102to support closed-loop force feedback, among other capabilities. Processor106comprises memory, in which the software described above is stored. In the illustrative embodiment, processor106is a personal computer.

Monitor108displays a rendering that is generated by processor106, in conjunction with the above-referenced software. The rendering, which in some embodiments is three-dimensional, is of a region of the body (e.g., isolated arm, thorax, neck, etc.) on which a simulated vascular-access procedure is being performed. The rendering advantageously depicts visual aspects such as, without limitation, the anatomical structures that underlie skin, local deformation of the skin in response to simulated contact, and tracking of a “virtual” instrument (e.g., a needle, etc.) through anatomical structures that underlie the skin.

The functional elements of haptics device102listed above that relate to human anatomical features or are otherwise intended to generate resistive forces that would be sensed when penetrating such anatomical features (elements222-228) are advantageously contained within housing216or otherwise located “underneath” pseudo skin220. In an actual vascular-access procedure, the needle or catheter, of course, remains outside of the body until inserted during the procedure. Likewise, in accordance with the illustrative embodiment, the end effector—needle/catheter module218—remains outside of housing216and pseudo skin220until a portion of it is inserted during a simulated vascular-access procedure. In some embodiments, housing216is subtly shaped like a portion of a human arm, yet is nondescript enough to avoid creating a discontinuity between what is seen and what is felt.

Pseudo skin220is a membrane that is used in conjunction with the simulation of skin-interaction techniques, such as palpation, occlusion, and skin stretch techniques. Pseudo skin220is advantageously, but not necessarily, imitation skin (i.e., skin-like in appearance). In embodiments in which pseudo skin220is imitation skin, it possesses any one of a number of natural flesh tones. In some embodiments, pseudo skin220is at least somewhat resilient to enable a user to perform skin-interaction techniques. In some embodiments, pseudo skin220comprises a thermoplastic elastomer such as Cawiton®, which is available from Wittenburg, B.V., Hoevelaken, Netherlands. The use of imitation skin, as opposed to mock skin, is desirable because it helps a user to “suspend disbelief,” which contributes to making simulator100more useful as a training tool.

As depicted inFIG. 3, pseudo skin220is accessed for insertion and skin-interaction techniques (e.g., palpation, occlusion, skin stretch, etc.) through openings330and332in housing216. Opening330defines palpation/occlusion region331(i.e., the site at which palpation and occlusion techniques are performed) and opening332defines skin-stretch region333(i.e., the site at which the skin-stretch technique is performed) and includes insertion point334for the end effector (e.g., needle/catheter module218).

The ability to perform skin-interaction techniques provides a more realistic simulation of vascular-access procedures. In some embodiments, this ability is provided in conjunction with palpation module222and skin-stretch module224. These modules, and illustrative embodiments thereof, are described in further detail applicant's co-pending U.S. patent application Ser. No. 10/807,017.

Pseudo skin220is disposed adjacent to the inside surface of housing216so that it appears to be nearly co-extensive (i.e., co-planar) with housing216at openings330and332. This is intended to create a subtle suggestion that the surface of housing216is “skin” at regions other than where pseudo-skin220is accessed for skin-interaction techniques. Consistent with human anatomy, the remaining functional elements of haptics device102(elements222-228), with the exception of needle/catheter module218, are “hidden” beneath pseudo skin220.

The end effector (e.g., needle/catheter module218, etc.) is inserted into haptics device102at insertion point334in opening332. In some embodiments, simulator100is capable of sensing orientation of the end effector, such as to determine the orientation of a feature of a needle or catheter. In some embodiments, the feature is a bevel. This is an important aspect of the real insertion technique, since proper bevel orientation reduces a patient's discomfort during needle/catheter insertion. In some embodiments, needle/catheter module218is configured to be very similar to a real needle and catheter.

Once inserted into haptics device102, the tip of needle/catheter module218engages receiver226, which, for the illustrative embodiment of a vascular access simulator, is referred to as a “needle-stick module.” Needle-stick module226supports the continued “insertion” of the needle/catheter module218. In particular, in some embodiments, needle-stick module226is configured to provide one linear degree of freedom and two rotational degrees of freedom (i.e., pitch and yaw). The linear degree of freedom provides a variable insertion depth, enabling a user to advance needle/catheter module218into the “patient's arm” (i.e., haptics device102). The rotational degrees of freedom enable a user to move (an engaged) needle/catheter module218up or down and left or right. In some embodiments, needle-stick module226measures insertion depth, and pitch (up/down) and yaw (left/right) angles.

In some embodiments, needle-stick module226provides “force feedback” to a user, whereby the user senses a variable resistance during continued advance (insertion) of needle/catheter module218. The resistance is intended to simulate penetration of the skin, a vein, and harder structures such as ligaments, bones, and the like. The resistance advantageously varies with insertion depth and the pitch and yaw of needle/catheter module218, as described further below.

It will be understood that the “measurements” of angle, position, etc. that are obtained by the functional elements described above are obtained in conjunction with various sensors and data-processing system104. In particular, most of the functional elements described above include one or more sensors. The sensors obtain readings from an associated functional element, wherein the readings are indicative of the rotation, displacement, etc., of some portion of the functional element. These readings provide, therefore, information concerning the manipulation of needle/catheter module218in addition to any parameters.

Each sensor generates a signal that is indicative of the reading, and transmits the signal to electronics/communications interface228. Sensors used in some embodiments include, without limitation, potentiometers, encoders, and MEMS devices. Those skilled in the art will know how to use and appropriately select sensors as a function of their intended use in conjunction with the functional elements described above.

Electronics/communications interface228receives the signals transmitted by the various functional elements of haptics device102and transmits them, or other signals based on the original signals, to data-processing system104. Furthermore, electronics/communications interface228distributes power to the various functional modules, as required.

As described later below, electronics/communications interface228also receives signals from data processing system104and transmits them to needle-stick module226, among any other modules within haptics device102, as part of a closed loop force-feedback system. In some embodiments, the signals received from data processing system104are amplified before they are transmitted to needle-stick module226, etc. As an alternative to having electronics/communications interface228transmit the signals that are received from data processing system104, in some embodiments, the electronics/communications interface generates new signals based on the received signals. This approach, which is typically referred to as embedded control, is well known in the art. It disadvantageously requires a substantial increase in processing power and data management (relative to simply transmitting the received signals, or simply amplifying the received signals) and is generally a less-preferred approach.

Data-processing system104receives the measurement data and, using the simulation software, calculates the forces that are being applied by the user during the skin-interaction procedures. Furthermore, using an anatomical model, data-processing system104calculates the position and angle of a virtual needle within a simulated anatomy (e.g., arm, etc.). Data-processing system104displays, on monitor108, a rendering of the appropriate anatomy (e.g., arm, etc.) and displays and tracks the course of a virtual needle within this anatomy.

Furthermore, based on the position and course of the virtual needle (as calculated based on the position and orientation of needle/catheter module218), data-processing system104generates control signals that are transmitted to needle-stick module226. These control signals vary the resistive force presented by needle-stick module226to account for various anatomical structures (e.g., vein, tissue, tendons, bone, etc.) that needle/catheter module218encounters, based on the simulation. As a consequence, the resistance to continued needle/catheter insertion that is experienced by a user of simulator100is consistent with the resistance that would be sensed by a practitioner during an actual vascular access procedure.

Having completed the overview of vascular-access simulator100and haptics device102, the end effector (in the illustrative embodiment needle/catheter module218) and receiver (in the illustrative embodiment needle-stick module226) will be described in further detail.

FIGS. 4A and 4Bdepict haptics device102and data processing system104of simulator100. In the embodiment depicted in these Figures, haptics device102includes needle/catheter module218, needle-stick module226and electronics/communications interface228. It will be appreciated that in other embodiments, other functional modules (such as those described previously) in addition to or instead of needle-stick module226and electronics/communications interface228are typically present within haptics device102.

The needle-stick module and the electronics/communications interface are disposed within housing216. Both needle/catheter module218and needle-stick module226are electronically coupled to electronics/communications interface228, and through it coupled to data processing system104. As previously described, electronics/communications interface228provides power to these and other modules, receives signals from these and other modules as well as data processing system104, and sends signals to needle-stick module226and data processing system104.

Needle-stick module226is disposed substantially beneath pseudo skin220and is accessible to needle/catheter module218via insertion point334. In some embodiments, a portion (i.e., guide1089, see ¶0086 andFIGS. 10A-10C) of needle-stick module226is raised slightly above the plane of pseudo skin220to simply the process of engaging needle/catheter module218to the needle-stick module. In the illustrative embodiment, insertion point334is an opening in pseudo skin220. In some other embodiments, the needle/catheter module penetrates pseudo skin220.FIG. 4Adepicts the simulator before a user has inserted needle/catheter module218into needle-stick module226.FIG. 4Bdepicts the simulator after a user has inserted the needle/catheter module into the needle-stick module.

FIGS. 5-7depict an illustrative embodiment of needle/catheter module218and its constituent parts. In the illustrative embodiment, needle/catheter module includes needle portion536and catheter portion554, which can be coupled to or decoupled from one another.FIG. 5depicts the needle portion and catheter portion coupled to one another.FIG. 6depicts only needle portion536andFIG. 7depicts only catheter portion554. When needle portion536is coupled to catheter portion554, needle650(FIG. 6) is received by catheter758(FIG. 7).

As depicted inFIG. 5, needle/catheter module218includes sensor538. In the illustrative embodiment, sensor538is disposed in needle portion536. In some embodiments, sensor538provides data that is indicative of the orientation of the bevel, such as bevel760of catheter portion554(see,FIG. 7). Those skilled in the art will know how to select and use a device to function as sensor538. In some embodiments, sensor538is one or more micro-electromechanical system (MEMS) devices. As is well known in the art, MEMS devices typically have a size within a range of about 100 nanometers to a millimeter, and are created using surface micro-machining techniques (e.g., depositing mechanical and sacrificial layers, selectively etching to pattern, etc.)

In the illustrative embodiment that is depicted inFIG. 6, needle portion536includes needle housing640, needle650, and wire652. Housing640includes surface features such as ergonomic grip642and ridge644. Needle portion536and catheter portion554are configured for locking engagement, such as by inserting ridge644into a complementary slot (not depicted) in coupler756of catheter554.

Needle housing640contains sensor538, which in the illustrative embodiment depicted inFIG. 6comprises two MEMS accelerometers646and648. The accelerometers are electrically coupled to wire652, which is, in turn, coupled to electrical/communications interface228. The accelerometers are oriented orthogonal to one another so that they detect motion along orthogonal axes. Each of accelerometers646and648is capable of generating a signal that is indicative of motion along two orthogonal axes. It is notable that while MEMS accelerometers646and648can detect motion along two orthogonal axes, this is not necessary for resolving the orientation of, for example, the bevel. This can be done by detecting motion along only one axis. This information obtained by the accelerometers is ultimately transmitted to data processing system104and used by it to resolve the orientation of housing640or anything rigidly coupled to it (such as catheter portion554) in two dimensions. MEMS accelerometers suitable for use as sensor538include, for example, dual-axis accelerometers with duty cycle output, such as model ADXL202E available from Analog Devices, Inc. of Norwood, Mass.

In the illustrative embodiment, needle portion536is connected via wire to electrical/communications interface228. But in some other embodiments, needle-catheter module218is a wireless device. In these other embodiments, needle portion536communicates wirelessly with either electrical/communications interface228or (directly) with data processing system104. In such embodiments, needle portion536, electrical/communications interface228, and data processing system104include a transceiver, receiver, or transmitter, as appropriate. In embodiments in which needle/catheter module218operates wirelessly, it advantageously includes its own power source, such as one or more lithium-ion batteries, etc. Those skilled in the art will know how to make and use embodiments of the present invention in which needle/catheter module218is configured for wireless operation.

In the illustrative embodiment, bevel760is formed on catheter758. Those skilled in the art of vascular-access techniques will recognize that in an authentic instrument (i.e., authentic needle and catheter) the bevel is typically formed in the needle rather than the catheter. Bevel760is formed on catheter758, rather than needle650, as a preferred location in view of other design decisions (in particular, the manner in which needle650is coupled to needle-stick module226, which is described in detail later in this specification). In other embodiments, the bevel is formed on needle650. In such other embodiments, it will be advantageous to suitably modify the way in which needle650couples to needle-stick module226.

Sensor864, which can be one or more sensors, senses the position of needle650/catheter758. In some embodiments, sensor(s)864obtains information indicative of the extent of penetration of the needle/catheter into needle-stick module226. In some other embodiments, sensor(s)864also measures the orientation of the needle/catheter, assuming that needle/catheter module218is free to move in other directions. In other words, sensor(s)864monitor movement along axes that align with one or more available degrees of freedom.

Sensor(s)864generates signal(s) indicative of the monitored movement. The sensor(s) are directly or indirectly coupled to data processing system104. The signals, or other signals derived therefrom, are transmitted from sensor(s)864and are ultimately received by data processing system104. Using the data contained in the signal(s), and in conjunction with anatomical model866and force-calculation software868, the data processing system:determines the anatomical features that the needle/catheter would encounter (skin, vein, ligaments, bone, etc.), based on its position, were it moving through an actual anatomy; andcalculates the resistive forces that would arise as the needle/catheter encounters these various anatomical features.

A control signal(s) is generated by controller870based on the force calculations. The control signal(s) is transmitted to haptics device102and is ultimately received by force-feedback assembly862.

Responsive to the control signal(s), force-feedback assembly862generates force FRthat opposes movement of the needle/catheter. In some embodiments, force FRonly opposes “forward” movement (i.e., movement in the direction of continued insertion) of the needle/catheter through needle-stick module226. In some other embodiments, forces are generated that oppose movement of the needle/catheter both in the forward and reverse direction (i.e., insertion and removal).

FIG. 9depicts further detail of an embodiment of needle-stick module226. In the embodiment that is depicted inFIG. 9, needle-stick module226includes movable member972. When needle/catheter module218is inserted into haptics device102, needle650or catheter758couples to movable member972. The movable member is capable of moving forward or backward along translational axis A-A; for example, as a user manipulates needle/catheter module218into or out of haptics device102. In some embodiments, sensor864A monitors translational motion of movable member972and, hence, the translational motion of needle/catheter module218.

It is desirable for movable member972to move with very low friction. In some embodiments, this is implemented via an arrangement that provides “rolling contact.” In other words, to the extent that movable member972contacts a surface, the contact involves a rolling member (e.g., pulleys against a cable, ball bearings against a surface, etc.) Rolling contact is to be distinguished, for example, from sliding contact, the latter typically associated with greater friction.

Referring now to the exploded view depicted inFIG. 10A, needle-stick module226comprises receiving module1076, base and gimbal assembly1078, and counterweight assembly1080. Receiving module1076couples to secondary-gimbal bracket1083, counterweight holder1081rigidly couples to pitch potentiometer shaft1084, and link1086couples, at one end, to receiving module1076(via to ball-joint ball1090) and at the other end to counterweight holder1081(see also,FIGS. 10B,10C). Base1079of needle-stick module226is disposed on the bottom inside surface of housing216in the manner depicted inFIGS. 4A and 4B.

The illustrative embodiment of needle-stick module226provides three degrees of freedom—one translational and two rotational—as follows. Movable member972moves within receiving module1076along translational axis1-1. This provides the “translational” degree of freedom. (See also,FIG. 10C, translational movement is movement in the directions indicated by path A-A.) Secondary gimbal bracket1083and receiving module1076rotate about pitch axis2-2. (See also,FIG. 10B, pitch is movement in the directions indicated by path B-B.) Primary-gimbal bracket1088and receiving module1076rotate about yaw axis3-3. (See also,FIG. 10C, yaw is movement in the directions indicated by path C-C.) Rotation about the pitch and yaw axes provide the two “rotational” degrees of freedom of needle-stick module226.

In the illustrative embodiment, pitch and yaw of receiving module1076are tracked by potentiometers. More particularly, pitch is evaluated using pitch potentiometer1092and yaw is evaluated using yaw potentiometer1094, as described further below. Potentiometers1092and1094are, therefore, specific embodiments of generic sensor(s)864ofFIG. 8.

With continuing reference toFIG. 10A, pitch potentiometer1092is coupled to the obscured side of potentiometer holding plate1096. As receiving module1076swings up or down (i.e., pitches), link1086forces counterweight holder1081to rotate about an axis that aligns with pitch potentiometer shaft1084(see also,FIG. 10B). Since counterweight holder1081is rigidly attached to potentiometer shaft1084, that shaft turns as the counterweight holder rotates. Rotation of the potentiometer shaft and, hence, pitching of receiving module1076is therefore “sensed” by pitch potentiometer1092. Pitch potentiometer1092is electrically coupled to electronics/communications interface228(not depicted inFIG. 10A, see, e.g.,FIGS. 4A and 4B). Pitch potentiometer1092generates a signal indicative of the sensed movement and transmits it to electronics/communications interface228and, through it, to data processing system104. It is notable that since counterweight1082moves along with counterweight holder1081, the weight of receiving module1076is counterbalanced through its full range of motion.

Still referring toFIG. 10A, yaw potentiometer1094is disposed beneath yaw potentiometer shaft1097and is coupled to an obscured surface of base1079. Primary-gimbal bracket1088is mechanically coupled to yaw potentiometer shaft1097by links1098and1099(see also,FIG. 10C). Yaw potentiometer shaft1097is coupled to yaw potentiometer1094in known fashion. Rotation of yaw potentiometer shaft1097and, hence, yawing of receiving module1076is therefore “sensed” by yaw potentiometer1094. The yaw potentiometer is electrically coupled to electronics/communications interface228(not depicted inFIG. 10A, see, e.g.,FIGS. 4A and 4B). Yaw potentiometer1094generates a signal indicative of the sensed movement and transmits it to electronics/communications interface228and, through it, to data processing system104. Potentiometers suitable for use as potentiometers1092and1094are commercially available from Clarostat Sensors and Controls, Inc. of El Paso, Tex., among others.

In use, the catheter and or needle of needle-catheter module218is inserted into guide1089. Once inserted into guide1089, the tip of the catheter or needle and movable member972couple to one another. In the illustrative embodiment, magnet973is disposed at the forward end of movable member972(see,FIGS. 10A and 12). The magnet is used as a means to readily and reversibly couple the tip of needle650or catheter758to movable member972.

It was previously disclosed that in some embodiments, movable member972is coupled to a force-feedback system, referred to earlier as force-feedback assembly862. As previously described, force-feedback assembly862generates a resistance to continued insertion of needle-catheter module218into receiving module1076. An illustrative embodiment of force-feedback assembly862and additional description of receiving module1076is now provided in conjunction withFIGS. 11A-11D.

FIG. 11Adepicts an exploded view of an embodiment of receiving module1076. In the illustrative embodiment, receiving module1076includes frame1149, which comprises lower plate1150and upper plate1152. The receiving module also includes movable member972and force-feedback assembly862, which comprises motor1156, motor encoder1158, motor pulley1160, pulleys1162, and cable1164(shown inFIG. 11Donly).

Movable member972is disposed between upper and lower plates1150and1152and is positioned between centrally-located openings1154in the plates. Referring toFIG. 11B, movable member972is suspended at pulleys1274A and1274B (see also,FIG. 12) by cable1164, which is depicted as a dashed line for clarity. Cable1164is fixed at one end by holder1166and fixed at the other end by holder1168. Holders1166and1168are coupled to one another by tensioning screw1170, which adjusts the tension in cable1164. Cable1164is supported at a variety of intermediate locations by pulleys1162(i.e.,1162A-1162D). The cable also wraps around motor pulley1160, thereby coupling movable member972to motor1156.

FIGS. 11C and 11Ddepict a bottom view of receiving module1076. These Figures depicts sequential “snap shots,” wherein needle650/catheter758is inserted deeper into receiving module1076(e.g., by a user practicing a vascular-access technique with needle/catheter module218, etc.). Since the needle/catheter is coupled to movable member972(e.g., by magnet973, etc.), the movable member is also moved “deeper” into receiving module1076. Indeed, once coupled, any movement of needle/catheter module218causes movable member972to advance or retreat along axis1-1within region1154of plates1150and1152.

As described above, motor1156is coupled to movable member972via cable1164(FIG. 11B). Any movement of the movable member therefore causes the motor to move. For example, as movable member972moves forward or “deeper” into receiving module1076, motor pulley1160turns in a clockwise direction (for the particular arrangement depicted inFIG. 11B). Movement of the motor pulley causes the motor to turn and this movement is captured by encoder1158(FIG. 11A) in known fashion. As a consequence, translational motion of movable member972, and, therefore, the position of needle/catheter module218, is sensed by encoder1158. The encoder is therefore an embodiment of sensor(s)864ofFIG. 8. The encoder is electrically coupled to electronics/communications interface228(see, e.g.,FIGS. 4A and 4B). Encoder1158generates a signal indicative of the movement of motor1156and transmits it to electronics/communications interface228and, through it, to data processing system104.

In addition as functioning as a means for tracking the position of movable member972(and needle/catheter module218), motor1156also functions as a key element of force-feedback assembly862.

In particular, responsive to a control signal (e.g., generated by controller870ofFIG. 8, etc.), which is based on calculations performed by data processing system104, the motor engages with a specified amount of torque in a counterclockwise direction (for the particular arrangement depicted inFIG. 11B). This generates a force, FR, which opposes or counters the force applied by a user during continued insertion of needle/catheter218. As previously described, force FRis intended to simulate the resistance that would be presented by various anatomical features, were the simulated vascular-access procedure an actual procedure that was being performed on a real anatomy.

It is notable that in the arrangement that is depicted inFIG. 11B, the insertion force applied by a user is aligned with the tension in cable1164and with the translational degree of freedom. As a consequence, no unusual or unrealistic torque sensations are experienced by a user as needle/catheter module218is inserted into receiving module1076.

A motor suitable for use in conjunction with the present invention is a coreless brushed DC motor, such as is commercially available from Maxon Precision Motors, Inc. of Fall River, Mass. In some embodiments, cable1164is made from stainless steel and the pulleys1162are nylon pulleys. In such embodiments, the force-feedback assembly has very low inertia, very low friction, and is very stiff. As will be appreciated by those skilled in the art, these are all attributes of a good haptics design.

It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. For example, in this specification, numerous specific details are provided in order to provide a thorough description and understanding of the illustrative embodiments of the present invention. Those skilled in the art will recognize, however, that the invention can be practiced without one or more of those details, or with other methods, materials, components, etc.

Furthermore, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the illustrative embodiments. It is understood that the various embodiments shown in the Figures are illustrative, and are not necessarily drawn to scale. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.