Method and apparatus for haptic simulation

A haptic simulation method determines a location of a needle assembly within a magneto-rheological fluid. The needle assembly within the magneto-rheological fluid is associated with a desired resistance value. A viscosity control signal representative of the desired resistance value is generated. The viscosity control signal is applied to a viscosity control device to vary a viscosity of the magneto-rheological fluid to achieve the desired resistance value.

TECHNICAL FIELD

This disclosure relates to haptic simulation and, more particularly, to simulated needle insertion and simulated fluid injection.

BACKGROUND

Over the past decade, the use of peripheral nerve blocks for intraoperative and postoperative analgesia, or pain control, has become increasingly popular. Though nerve block procedures may present fairly low risk in a hospital setting, the same is not always true on the battlefield, where severe trauma cases may be prevalent and properly trained pain management specialists may be in high demand. There may be a need for all military anesthesiologists to undergo training for the administration of peripheral nerve blocks, yet currently no suitable curriculum or training system exists for hospitals and medical schools. Industries and institutions have been involved in developing a natural, immersive virtual environment, incorporating haptic, visual, and auditory feedback. Anesthesiologists may use realistic interface platforms of needle and syringe in simulated procedures. This may be achieved through a needle tracking system and innovative devices for generating haptic feedback during needle insertion, needle injection, and palpation, for example.

SUMMARY OF DISCLOSURE

According to a first aspect of this disclosure, a method includes determining a location of a needle assembly within a magneto-rheological fluid. The location of the needle assembly within the magneto-rheological fluid is associated with a desired resistance value. A viscosity control signal representative of the desired resistance value is generated. The viscosity control signal is applied to a viscosity control device to vary a viscosity of the magneto-rheological fluid to achieve the desired resistance value.

One or more of the following features may be included. The desired resistance value may emulate a resistance required to displace the needle assembly through one or more layers of tissue (e.g., skin; fat; nerves; cartilage; muscle; and bone). Varying the viscosity of the magneto-rheological fluid may include applying a magnetic field to the magneto-rheological fluid.

According to another aspect of this disclosure, a simulation apparatus includes a container assembly. A magneto-rheological fluid is positioned within the container assembly. A needle assembly is configured to be displaceable through the magneto-rheological fluid. A displacement sensor is configured to determine a location of the needle assembly within the magneto-rheological fluid and generate a location signal indicative of the location. A resistance control device, responsive to the location signal, is configured to: associate the location of the needle assembly within the magneto-rheological fluid with a desired resistance value, and generate a viscosity control signal representative of the desired resistance value. A viscosity control device, responsive to the viscosity control signal, is configured to vary the viscosity of the magneto-rheological fluid to achieve the desired resistance value.

One or more of the following features may be included. The viscosity control device may include an electromagnetic field winding and a magnetic flux guide. The magnetic flux guide may be configured to provide a magnetic field within the container assembly. The magnetic field may vary the viscosity of the magneto-rheological fluid to achieve the desired resistance value. A pitch-roll actuator may be configured to allow the simulation apparatus to be displaced within a plurality of axes.

According to another aspect of this disclosure, a simulation apparatus includes a syringe assembly. A magneto-rheological fluid is positioned within the syringe assembly, the syringe assembly including a plunger assembly for displacing at least a portion of the magneto-rheological fluid from an orifice of the syringe assembly. A viscosity control device, responsive to a viscosity control signal, is configured to vary a viscosity of the magneto-rheological fluid displaced from the orifice of the syringe assembly to achieve a desired plunger resistance value. One or more of the following features may be included. The viscosity control device may include an electromagnetic field winding and a magnetic flux guide. The magnetic flux guide may be configured to provide a magnetic field within a tube assembly coupled to the orifice of the syringe assembly. The magnetic field may vary the viscosity of the magneto-rheological fluid to achieve the desired plunger resistance value. The simulation apparatus may also include a magneto-rheological fluid tank, wherein the magneto-rheological fluid tank may be configured to receive the magneto-rheological fluid from the tube assembly. The simulation apparatus may also include a resistance control device for generating the viscosity control signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1, there is shown simulation apparatus10for simulating, at least in part, haptic feedback produced by insertion of a needle into tissue. Simulation apparatus10may include container assembly12. As is known to one of skill in the art, container assembly12may include any container suitable for containing magneto-rheological fluid14(e.g., a plastic container or a metallic container). Further, and as will be discussed in greater detail below, magneto-rheological fluid14may include micrometer-sized magnetic particles suspended in a carrier fluid, e.g., oil. Moreover, when subjected to a magnetic field, magneto-rheological fluid14may experience significantly increased viscosity, even to the point of becoming a viscoelastic solid.

Magneto-rheological fluid14may be positioned within container assembly12. For example, container assembly12may contain at least a portion of magneto-rheological fluid14. Additionally, needle assembly16may be configured to be displaceable through magneto-rheological fluid14(e.g., in the direction of arrow17). Specifically, at least a portion of needle assembly16may be inserted into magneto-rheological fluid14, which may be contained within container assembly12.

Referring also toFIG. 2, simulation apparatus10may also determine50a location of needle assembly16within magneto-rheological fluid14. For example, simulation apparatus10may include displacement sensor18, which may be configured to determine50a location (not shown) of needle assembly16and generate52a location signal (not shown) that may be indicative of the location. Examples of displacement sensor18may include, but are not limited to: camera-based tracking systems and radio-frequency (“RF”) tracking systems.

Continuing with the above-stated example of a camera-based tracking system, displacement sensor18may include an optical camera (not shown) positioned to receive visually-perceptible information regarding the essentially linear location of needle assembly16within container assembly12. Displacement sensor18may then generate52a location signal that may represent the location of needle assembly16within container assembly12(e.g., needle assembly16may be essentially linearly displaced4millimeters with respect to container assembly12).

The location signal generated52may be transmitted along location signal line20to resistance control device22. Resistance control device22may be responsive to the location signal received on location signal line20, and may be configured to associate54the location of needle assembly16within magneto-rheological fluid14with a desired resistance value. As will be discussed in greater detail below, a desired resistance value may represent the resistance that would be felt on needle assembly16if needle assembly16was actually being inserted through one or more layers of tissue (as opposed to magneto-rheological fluid14).

Associating54the location of needle assembly16with a desired resistance value may include emulating56a resistance required to displace needle assembly16through one or more layers of tissue. For example, and referring also toFIG. 3, the one or more layers of tissue may include one or more of: skin100; fat (not shown); nerves (not shown); cartilage (not shown); muscle102; and bone (not shown). As is known in the art, different layers of tissue may have different densities. Accordingly, the resistance required (i.e., the desired resistance value) for emulating56the passage of needle assembly16through skin100is typically less than the resistance required for emulating56the passage of needle assembly16through bone.

As needle assembly16is displaced through the one or more layers of tissue, the resistance imparted upon it may vary depending on the stage of insertion and the forces acting on needle assembly16. Generally, the insertion process may include four events: tissue deformation, puncture, insertion and tissue relaxation, and withdrawal. During the insertion process, the forces acting on needle assembly16may include, but are not limited to: the force at tip104of needle assembly16required for penetrating the one or more layers of tissue; the friction force of the one or more layers of tissue sliding along shaft106of needle assembly16; and the clamping force of the one or more layers of tissue on needle assembly16. To accurately simulate the insertion of needle assembly16into the one or more layers of tissue, the resistance created by each of these events and forces may be emulated56by resistance control device22.

As is known in the art, as needle assembly16is inserted further into the one or more layers of tissue, it may undergo a series of micro-punctures where the resistance may increase at the threshold of each micro-puncture, and may then decrease after such micro-puncture. Further, after the initial puncture and insertion of needle assembly16into skin100, the resistance may increase relatively linearly along the insertion path as the surface area of needle assembly16in contact with the layers of tissue increases. This may result in greater friction and greater clamping force of the one or more layers of tissue along shaft106of needle assembly16.

An exception to the relatively linear increase in resistance may exist with regard to puncture events along the insertion path, as puncture events may result from a change in the stiffness of the one or more layers of tissue due to their non-homogeneity. A puncture event may include, but is not limited to, deformation of the one or more layers of tissue, yielding increased resistance, followed by puncture, yielding a sudden decrease in resistance.

Utilizing the location signal provided by displacement sensor18via location signal line20, resistance control device22may associate54the location of needle assembly16within magneto-rheological fluid14with a desired resistance value, wherein the desired resistance value may emulate the resistance indicated by, e.g., exemplary insertion resistance profile108.

After associating54the location of needle assembly16with a desired resistance value, resistance control device22may generate58a viscosity control signal that may be representative of the desired resistance value. The viscosity control signal may be transmitted along viscosity control signal line24to viscosity control device26. The viscosity control signal may then be applied60to viscosity control device26to vary a viscosity of magneto-rheological fluid14to achieve the desired resistance value.

Viscosity control device26, responsive to the viscosity control signal provided via viscosity control signal line24, may be configured to vary the viscosity of magneto-rheological fluid14to achieve the desired resistance value. As discussed above, and as is known in the art, magneto-rheological fluid14may include micrometer-sized magnetic particles suspended in a carrier fluid, e.g., oil. Moreover, when subjected to a magnetic field, magneto-rheological fluid14may experience significantly increased viscosity, even to the point of becoming a viscoelastic solid. Accordingly, the viscosity of magneto-rheological fluid14may be varied by applying62a magnetic field to magneto-rheological fluid14.

As will be discussed in greater detail below, viscosity control device26, which may include electromagnetic field winding28and magnetic flux guide30, may vary the viscosity of magneto-rheological fluid14by varying the electric current it transmits to electromagnetic field winding28. Specifically and as is known in the art, the strength of a magnetic field may be varied by proportionally varying the amplitude of the current passing through electromagnetic field winding28. Accordingly, in the event that a higher level of resistance is required/desired, viscosity control device26may increase the strength of the magnetic field experienced by magneto-rheological fluid14and thus increase the level of resistance (i.e., the desired resistance value) experienced by the user (not shown) of simulation apparatus10. Conversely, in the event that a lower level of resistance is required/desired, viscosity control device26may decrease the strength of the magnetic field experienced by magneto-rheological fluid14and thus decrease the level of resistance (i.e., the desired resistance value) experienced by the user (not shown) of simulation apparatus10.

Magnetic flux guide30may be configured to provide the above-described magnetic field within container assembly12(i.e., the container in which magneto-rheological fluid14is contained).

Simulation apparatus10may also include pitch-roll actuator32that may be configured to allow simulation apparatus10to be displaced within a plurality of axes. As the insertion of needles into tissue may be performed from a variety of different angles, pitch-roll actuator32may allow simulation apparatus10to simulate needle insertion from many of the different angles.

Referring also toFIG. 4, there is shown an alternative embodiment simulation apparatus10′ for simulating injection of fluids into the above-described layers of tissue. Simulation apparatus10′ may include syringe assembly150. Magneto-rheological fluid152may be positioned within syringe assembly150, wherein syringe assembly150may include plunger assembly154for displacing at least a portion of magneto-rheological fluid152from orifice156of syringe assembly150. For example, as plunger assembly154is depressed, magneto-rheological fluid152may be displaced from orifice156and into tube assembly158.

To simulate the resistance imparted on plunger assembly154when injecting fluids into one or more layers of tissue, simulation apparatus10′ may include resistance control device160for generating a viscosity control signal representative of a desired plunger resistance value. Resistance control device160may be manually programmed by a user (not shown) to generate the desired plunger resistance value. Alternatively, resistance control device160may be remotely controlled by an external device (e.g., a computing device; not shown) to automatically generate the desired plunger resistance value.

The viscosity control signal may be transmitted via viscosity control signal line162to viscosity control device164. For example, if simulation apparatus10′ is being used to simulate the injection of fluids into skin100, the desired plunger resistance value may emulate the resistance imparted on plunger assembly154based upon the empirically-defined resistance of skin100to the absorption of a fluid. Specifically, resistance control device160may be configured to adjust the viscosity of magneto-rheological fluid152so that simulation apparatus10′ emulates the resistance that would be experienced by a user (not shown) when injecting e.g., saline solution into skin100. As the resistance of skin100to the absorption of e.g., saline solution may be different than the resistance experienced when injecting saline solution into muscle102(i.e., a denser tissue), resistance control device160may be configured to adjust the level of resistance experienced. Accordingly and in the event that the injection of e.g., saline solution into muscle tissue is being simulated, resistance control device160may generate a viscosity control signal representative of a higher desired plunger resistance value (i.e., when compared to injecting saline solution into skin100).

Viscosity control device164, which is responsive to the above-described viscosity control signal provided via control signal line162, may be configured to vary the viscosity of magneto-rheological fluid152to achieve a desired plunger resistance value. As discussed above, the desired plunger resistance value may emulate a force required to inject a fluid (e.g., saline solution) into one or more layers of tissue.

Viscosity control device164, which may include electromagnetic field winding166and magnetic flux guide168, which may vary the viscosity of magneto-rheological fluid152by varying the amplitude of the electric current that viscosity control device164provides to electromagnetic field winding166. As discussed above, tube assembly158may be coupled to orifice156of syringe assembly150. Moreover, magnetic flux guide168may be configured to provide a magnetic field within tube assembly158(i.e., at an area proximate magnetic flux guide168) to vary the viscosity of magneto-rheological fluid152proximate magnetic flux guide168and achieve the desired plunger resistance value.

Simulation apparatus10′ may also include magneto-rheological fluid tank170, wherein magneto-rheological fluid tank170may be configured to receive magneto-rheological fluid152from tube assembly158. For example, as magneto-rheological fluid152is displaced from orifice156into tube assembly158, a reservoir may be necessary to contain the displaced magneto-rheological fluid152. Accordingly, magneto-rheological fluid tank170may function as a reservoir for containing at least a portion of the displaced magneto-rheological fluid152.