Patent ID: 12226109

SUMMARY OF THE DISCLOSURE

A surgical drill for actuating a drill bit is provided. The drill includes a housing, a probe moveably mounted to said housing and adapted for placement against a workpiece, and a transducer assembly. The transducer assembly includes a gear coupled to the probe and configured to rotate more than 360 degrees about a gear axis upon the movement of the probe relative to the housing. The gear having a reference point having an angular path of rotation about the gear axis being divided into a first arcuate region and a second arcuate region. The first arcuate region being separate from the second arcuate region. A transducer comprising at least two potentiometers is also included, with each of the at least two potentiometers coupled to the gear. A first of the at least two potentiometers is configured to detect a rotational position of the reference point in the first arcuate region and a second of the at least two potentiometers is configured to detect the rotational position of the reference point in at least the second arcuate region, the first rotational sensor being incapable of detecting the reference point in the second arcuate region.

A method for determining a bore depth in a workpiece formed by a drill bit attached to a drill is also provided, with the drill including a housing, a probe coupled to the housing, and a transducer assembly including a gear coupled to the probe and a transducer including at least two rotational sensor devices coupled to the gear. The method includes the steps of determining a first rotational position of the gear, determining a number of full rotations of the gear in a single rotational direction about a gear axis from the determined first rotational position, with each of the full rotations corresponding to a predefined amount of movement of the probe relative to the housing. The method also includes determining a second rotational position of the gear, the determined second rotational position the same or different than the determined first rotational position, and determining an amount of movement of the probe relative to the housing from the determined first and second rotational position and from the determined number of full rotations of the gear.

The surgical drill may include a housing, a coupling assembly disposed within the housing adapted to releasably couple the drill bit, a probe moveably mounted to said housing and adapted for placement against tissue. The drill may also include a transducer assembly including a gear coupled to the probe and configured to rotate more than 360 degrees about a gear axis upon the movement of the probe relative to the housing, the gear having a reference point having an angular path of rotation about the gear axis being divided into a first arcuate region and a second arcuate region, the first arcuate region being separate from the second arcuate region. The transducer assembly may also include a transducer comprising at least two rotational sensor devices, each of the at least two rotational sensors fixed rotationally relative to the gear, with the first rotational sensor configured to detect a rotational position of the reference point in the first arcuate region and a second rotational sensor configured to detect the rotational position of the reference point in the second arcuate region. The first rotational sensor being incapable of detecting the reference point in the second arcuate region, with the at least two rotational sensors adapted for independently generating a output signal corresponding to the detected rotational position of the reference point in said respective first and second arcuate region. The drill also includes a controller configured to receive each of the independently generated output signals and, based on each of the independently generated output signals, determine the depth of the bore in the tissue formed by the drill bit.

DETAILED DESCRIPTION

With reference to the drawings, where like numerals are used to designate like structure throughout the several views, a surgical system, or surgical drill, is shown at60inFIGS.1-2for performing an operational function that is typically associated with medical and/or surgical procedures. In the representative configuration illustrated herein, the surgical system60is employed to facilitate penetrating a workpiece, such as tissue or bone of a patient. As used herein, unless otherwise indicated, the term workpiece is understood to alternatively refer to tissue and/or bone. To this end, the illustrated configuration of the surgical system60comprises a handheld surgical instrument62and an end effector assembly, generally indicated at64. The end effector assembly64, in turn, comprises a drill bit66and may also include a tip protector68. As is best depicted inFIG.2, the drill bit66extends generally longitudinally along an axis AX between a cutting tip portion, generally indicated at70, and an insertion portion, generally indicated at72. The cutting tip portion70is configured to engage the workpiece, and the insertion portion72is configured to facilitate releasable attachment of the drill bit66to the surgical instrument62.

In order to help facilitate attachment of the drill bit66to the surgical instrument62, in some configurations, the tip protector68is configured to releasably secure to the cutting tip portion70of the drill bit66while concealing at least a portion of the cutting tip portion70of the drill bit66, thereby allowing a user (e.g., a surgeon) of the surgical system60to handle and position the drill bit66safely during attachment to the surgical instrument62. Once the end effector assembly64has been attached to the surgical instrument62, the tip protector68is subsequently removed from the cutting tip portion70of the drill bit66, and the surgical system60can then be utilized to penetrate the workpiece.

Referring now toFIGS.1-6, in the representative configuration illustrated herein, the surgical instrument62is realized as a handheld drill with a pistol-grip shaped handpiece body74which releasably attaches to a battery76(battery attachment not shown in detail). However, it is contemplated that the handpiece body can have any suitable shape with or without a pistol grip. While the illustrated surgical instrument62employs a battery76which is releasably attachable to the handpiece body74to provide power to the surgical instrument62utilized to rotate the drill bit66, it will be appreciated that the surgical instrument62may be configured in other ways, such as with an internal (e.g., non-removable) battery, or with a tethered connection to an external console, power supply, and the like. Other configurations are contemplated.

In the illustrated configuration, the battery76or other power source provides power to a controller78(depicted schematically inFIG.5) which, in turn, is disposed in communication with an input control80and an actuator assembly82(see alsoFIG.3). The input control80and the actuator assembly82are each supported by the handpiece body74. The controller78is generally configured to facilitate operation of the actuator assembly82in response to actuation of the input control80. The input control80has a trigger-style configuration in the illustrated configuration, is responsive to actuation by a user (e.g., a surgeon), and communicates with the controller78, such as via electrical signals produced by magnets and Hall effect sensors. Thus, when the surgeon actuates the input control80to operate the surgical instrument62, the controller78directs power from the battery76to the actuator assembly82which, in turn, generates rotational torque employed to rotate the drill bit66, as described in greater detail below. The handpiece body74, the battery76, the controller78, and the input control80could each be configured in a number of different ways to facilitate generating rotational torque without departing from the scope of the present disclosure.

As also shown inFIG.3, the actuator assembly82generally comprises an electric motor84and a gearset86which are each supported within the handpiece body74. The motor84is configured to selectively generate rotational torque in response to commands, signals, and the like received from the controller78. As is best shown inFIG.5, the motor84comprises a rotor cannula88supported for rotation about the axis AX by a pair of bearings90. A drive gear92arranged adjacent to the gearset86is coupled to and rotates concurrently with the rotor cannula88, and is employed to transmit rotational torque to the gearset86. To this end, in the illustrated configuration, the gearset86is realized as two-stage compound planetary arrangement and generally comprises a ring gear housing94which, among other things, rotationally supports an output hub96via a bearing90, as well as one or more retaining clips98, washers100, and/or seals102. However, other configurations of the gearset86are contemplated.

Further details of the gearset86are described, for example, in U.S. patent application Ser. No. 15/887,507, filed on Feb. 2, 2018 and entitled “Drill Bit for Handheld Surgical Instrument, the contents of which are herein incorporated by reference in their entirety, and describe wherein the rotation of the drive gear92via actuation of the motor84effects concurrent rotation of the output hub96, and wherein the output hub96rotates concurrently with the drill bit66. The actuator assembly82could be configured in other ways without departing from the scope of the present disclosure. By way of non-limiting example, while the illustrated actuator assembly82employs a compound planetary arrangement to adjust rotational speed and torque between the drive gear92of the motor84and the output hub96, other types of gearsets86could be utilized in some configurations. Moreover, while the illustrated actuator assembly82employs an electrically-powered brushless DC motor to generate rotational torque, other types of prime movers could be utilized. Other configurations are contemplated.

As noted above, rotational torque generated by the motor84effects rotation of the output hub96which, in turn, rotates concurrently with the drill bit66. To this end, and as is best shown inFIGS.2-5, the surgical instrument62further comprises a drive assembly114which generally extends through the various cannulated components of the actuator assembly82into splined engagement with the output hub96of the gearset86. The drive assembly114is configured to facilitate releasable attachment between the drill bit66and the surgical instrument62. The drive assembly114generally comprises a driving cannula116, a driving head118, and a driving body120which extends between, and rotates concurrently with, the driving cannula116and the driving head118. The drive assembly114is supported for rotation about the axis AX within the handpiece body74via splined engagement with the output hub96adjacent the driving cannula116, and via an arrangement of bearings90, snap rings100, and seals102adjacent the driving head118(seeFIG.6).

Further details of the drive assembly114are also described, for example, in U.S. patent application Ser. No. 15/887,507, the contents of which are also herein incorporated by reference in their entirety. In the illustrated configuration, the driving head118of the drive assembly114comprises a coupling, generally indicated at126, which is provided to facilitate transmitting rotational torque when the surgical instrument62is utilized in connection with other applications besides rotating the drill bit66of the present disclosure. More specifically, the illustrated drive assembly114is configured such that the surgical instrument62can rotate, drive, or otherwise actuate a number of different types of surgical instruments, tools, modules, end effectors, and the like, which can be configured to engage and rotate concurrently with either the bore122of the driving cannula116, or the coupling126of the driving head118. It will be appreciated that this configuration allows the same surgical instrument62to be utilized in a broad number of medical and/or surgical procedures. However, it is contemplated that the drive assembly114could be configured differently in some configurations, such as to omit a driving head118with a coupling126in configurations where the surgical instrument62configured for dedicated use with the drill bit66of the present disclosure.

Referring back toFIGS.1-3the illustrated configuration of the surgical instrument62further comprises a release mechanism, or coupling mechanism, generally indicated at150, configured to facilitate removal of the drill bit66. The coupling mechanism150generally comprises a release subassembly152, a keeper body154, and a housing adapter156. The keeper body154and the housing adapter156are respectively configured to secure the release subassembly152to the actuator assembly82and the handpiece body74, and could be realized with a number of different configurations or could be integrated into other parts of the surgical instrument62in some configurations.

As noted above, the drill bit66of the present disclosure generally extends along the axis AX between the cutting tip portion70and the insertion portion72, and is configured for releasable attachment to the surgical instrument62described herein and illustrated throughout the drawings via engagement between the interface124of the drill bit66and the bore122of the driving cannula116of the drive assembly114. The driving cannula116, in turn, cooperates with the output hub96of the gearset86of the actuator assembly82to facilitate rotating the drill bit66about the axis AX.

Referring now toFIG.2, the drill bit66comprises a shank, generally indicated at176, which extends along the axis AX between a proximal end178and a distal end180. The distal end180of the shank176is provided with flutes182which are helically disposed about the axis AX and extend to the tip of the drill bit66to promote workpiece, such as tissue, penetration (seeFIG.2). In the illustrated configuration, the drill bit66is also provided with a bearing region184coupled to the shank176between the proximal end178and the distal end180. The bearing region184is sized so as to be received within and rotate relative to the measurement probe134of the measurement module128. Here, the bearing region184essentially defines a “stepped” outer region of the shank176that affords rotational support along the length of the drill bit66, and has a larger diameter than adjacent distal and proximal regions of the shank176in the illustrated configuration. However, it will be appreciated that the bearing region184of the shank176of the drill bit66could configured in other ways without departing from the scope of the present disclosure. Furthermore, while described as a drill bit66in the present disclosure, it is also contemplated that the drill bit66could have similar features and be configured as another suitable end effector, or rotary end-effector, such as a bur or reamer.

The illustrated configuration of the surgical system60further comprises the measurement module, generally indicated at128, which may be configured to releasably attach to the surgical instrument62to provide the surgeon with measurement functionality during use. To this end, and as is best shown inFIGS.4and5, the measurement module128may generally comprises a housing130, a guide bushing132, a measurement probe134(i.e., a probe or a measurement cannula), and a sensor assembly, here a transducer assembly136. The housing130may be releasably attachable to the surgical instrument62and generally support the various components of the measurement module128. The illustrated housing130is formed as a pair of housing components138which interlock or otherwise attach together, and may be configured for disassembly to facilitate cleaning or servicing the measurement module128. It should be appreciated that the measurement module may be formed as an integral component of the surgical instrument as well.

In the illustrated configuration, the housing components138and the guide bushing132comprise correspondingly-shaped features arranged to prevent relative axial and rotational movement therebetween, such as via notches formed in the guide bushing132which fit into webs or ribs formed in the housing components138(not shown in detail). The guide bushing132further comprise a window142for use with the transducer assembly136as described in detail below.

The measurement probe134may be disposed within the guide bushing132and is supported for translational movement along the axis AX relative to the handpiece. An elongated recessed slot143(partially depicted inFIG.2) is formed transversely into the measurement probe134and extends longitudinally. While not specifically illustrated herein, the elongated recessed slot143is shaped and arranged to receive a travel stop element which, in turn, is supported by the housing130and likewise extends through an aperture formed transversely through the side of the guide bushing132; this arrangement serves both to limit how far the measurement probe134can be axially extended or retracted relative to the guide bushing132, and also prevents the measurement probe134from rotating about the axis AX. However, it will be appreciated that the measurement module128could be configured to limit or prevent movement of the measurement probe134in other ways without departing from the scope of the present disclosure.

As illustrated, the measurement probe134further comprises rack teeth144which are disposed in meshed engagement with a gear146of the transducer assembly136. As shown inFIG.5, the window142of the guide bushing132is arranged adjacent to the transducer assembly136to facilitate the meshed engagement between the rack teeth144and the gear146. The gear146includes a shaft portion147extending along a common gear axis CAX. The gear146itself is rotatable 360 degrees or more about the common gear axis CAX as the probe134moves along the axis AX relative to the housing130.

The transducer assembly136is responsive to rotation of the gear146resulting from axial movement of the measurement probe134in order to generate electrical signals representing changes in the position of the measurement probe134relative to the housing130along the axis AX. Thus, it will be appreciated that the transducer assembly136is able to provide the surgical instrument62with enhanced functionality. By way of example, in some configurations, the transducer assembly136may be disposed in communication with the controller78, which may be configured to interrupt or adjust how the motor84is driven based on movement of the measurement probe134, such as to slow rotation of the drill bit66at a specific drilling depth into the workpiece. The transducer assembly136may also be disposed in communication with an output device148, such as a display screen, one or more light-emitting diodes (LEDs), and the like, to provide the surgeon with information relating to movement of the measurement probe134, such as to display a real-time drilling depth, a recorded historical maximum drilling depth, and the like. Other configurations are contemplated.

The controller78comprises one or more microprocessors for processing instructions or for processing algorithms stored in memory to carry out the functions described herein. Additionally or alternatively, the controller78may comprise one or more microcontrollers, subcontrollers, field programmable gate arrays, systems on a chip, discrete circuitry, and/or other suitable hardware, software, or firmware that is capable of carrying out the functions described herein. The controller78may be carried in the handpiece body74as illustrated inFIG.5, or elsewhere in the surgical system60, or may be remotely located. Memory may be any memory suitable for storage of data and computer-readable instructions. For example, the memory may be a local memory, an external memory, or a cloud-based memory embodied as random access memory (RAM), non-volatile RAM (NVRAM), flash memory, or any other suitable form of memory.

In certain embodiments, the controller78comprises an internal clock to keep track of time. In one embodiment, the internal clock is a microcontroller clock. The microcontroller clock may comprise a crystal resonator; a ceramic resonator; a resistor, capacitor (RC) oscillator; or a silicon oscillator. Examples of other internal clocks other than those disclosed herein are fully contemplated. The internal clock may be implemented in hardware, software, or both. In some embodiments, the memory, microprocessors, and microcontroller clock cooperate to send signals to and operate the various components to meet predetermined timing parameters.

In the embodiment described herein, and as best shown inFIGS.6-8, the transducer assembly136includes at least two rotational sensor devices, here shown as a pair of potentiometers500,501, which are positioned in proximity to one another within the housing portion138. For ease of description below, a pair of potentiometers500,501are described hereinafter.

As best shown inFIGS.7-8, each of the potentiometers500,501, which may be the same or different, are rotatable potentiometers and include a body portion502and a rotor portion507positioned within the body portion502. The rotor portion507of each of the potentiometers500,501is coupled to the gear146via the shaft portion147and is thus rotatable as the gear146rotates about the common gear axis CAX. The body portion502is fixedly coupled to the housing portion138, and thus does not rotate as the rotor portion507rotates. The body portion502, in certain embodiments, is integral with the housing portion138. In particular, the rotor portions507of the potentiometers500,501are rotatable 360 degrees about the common gear axis CAC as the gear146rotates. In other words, the potentiometers500,501are of the type that do not include stops (i.e., stop members) that limit the rotation of the rotor portions507relative to the body portions502to less than 360 degrees of rotation. Stated still another way, the rotor portions507are freely rotating with the gear146.

The body portion502includes a pair of terminal portions503,504connected to a resistive element505. The first terminal portion503is connected (i.e., is electrically connected) to a power source, such as the battery76, and is supplied with a first reference signal (i.e., a predefined voltage) from the power source. The second terminal portion504is connected to a second reference signal. In certain embodiments, the second reference signal is a ground. An inner channel (not shown) of the body portion502is provided to serve as the void for containing conductors (such as a flex circuit) that extend from the respective terminal portions503,504and506. The body portion502also includes a third terminal portion506that is connected (i.e., electrically connected) to the controller78.

The rotor portion507of each of the potentiometers500,501also includes a wiper arm508that extends radially outward from the common gear axis CAX, with its radially outward end512configured to be connected to (i.e., contact, or electrically connect) the resistive element505or to be positioned along the gap511depending upon its relative rotational positioning of the wiper arm508about the common gear axis CAX with respect to the body portion502. Another portion of the wiper arm508, shown here as the radially inward end513that terminates at a point corresponding to the common gear axis CAX, is connected (i.e., electrically connected) to the third terminal portion506. The gear146is connected to each one of the respective rotor portions507by way of the shaft portion147. Therefore, the rotation of the gear146about the common gear axis CAX results in the like rotation of the wiper arms508of the potentiometers500,501about the common gear axis CAX and about the respective static body portions502.

The resistive element505may be arcuate in shape, defining an arcuate length AL between the pair of terminal portions503,504, and is positioned along a surface of the body portion502between the terminal portions503,504. A gap511extends along a portion of the body portion502between the second terminal portion504and the first terminal portion503and defines an additional arcuate length AAL that does not include the resistive element505.

As noted above, the length of the wiper arm508, corresponding to the radius (r) of the wiper arm508from the radially inward end513to the radially outward end512, is configured such that the radially outward end512of the wiper arm508is connected to the resistive element505or is positioned along the gap511, and as such the arcuate length AL of the resistive element502and the additional arcuate length AAL of the gap511corresponds to the arc defined by the radially outward end512of the wiper arm508as it rotates 360 degrees about the common gear axis CAX. The total arcuate length of this arc, which corresponds to the sum of the arcuate length AL and the additional arcuate length AAL, is equal to 2πr, with r defined as the radial length of the wiper arm508from the radially outward end512to the center of rotation CAX.

In certain embodiments, the arcuate length AL of the resistive element505is less than or equal to 11πr/6 (corresponding to less than or equal to 330 degrees of the 360 degrees of rotation of wiper arm508in a single rotation of the gear146), while the corresponding arcuate length AAL corresponding to the gap511is greater than or equal to πr/6 and less than 2πr (corresponding to the remainder of the 360 degrees of rotation of wiper arm508in a single rotation of the gear146, i.e., greater than or equal to 30 degrees and less than 360 degrees of rotation in a single rotation of the gear146), with the total length equal to 2πr as noted above.

When the wiper arm508of one or both of the potentiometers500,501is positioned such that it is in contact with the resistive element505, an output signal is generated from the wiper arm508that is sent to the controller78, with the output signal corresponding to the relative positioning of the wiper arm508along the arcuate length AL of the resistive element505and scaled with respect to the received first reference signal received by the resistive element from the first terminal portion503. The scale of the first reference signal received by the controller78through the wiper arm508and third terminal portion506, as one of ordinary skill appreciates, is stronger when the wiper arm508is positioned nearer to the first terminal portion103and is progressively weaker as the wiper arm508is rotated to a position nearer to the second terminal portion504. Conversely, when the wiper arm508of one of the potentiometers500,501is positioned within the gap511, an interrupted signal or no signal is generated from the wiper arm508that is sent to the controller78(known as the floating position, corresponding to a high ohmic impedance). The generated output signal or signals received by the controller78, or the interrupted signals, are interpreted by the controller78through its stored algorithms to determine the relative positioning of the probe100relative to the housing130, and thus use the information to determine the relative depth of the bore in the workpiece, such as tissue or bone, formed by the drill bit, as will be explained further below.

As also illustrated inFIGS.6-8, the potentiometers500,501are stacked adjacent to each other in the z-direction in a manner such that the wiper arm508of at least one of the pair of potentiometers500,501remains in contact with its respective resistive element505at all times, regardless of relative rotational positioning of wiper arms508of the pair of potentiometers500,501. Accordingly, at all times, at least one generated output signal via the wiper arm508in contact with the resistive element505is received by the controller78that can be used to determine the relative depth of the bore in the workpiece formed by the drill bit, as will be explained further below.

To accomplish this, the body portion502of one of the potentiometers500is rotatedly offset about the common gear axis CAX relative to the body portion502of the other one of the potentiometers501such that the resistive element505of the second potentiometer501is aligned along at least the entirety of the gap511of the first potentiometer500, when viewed in the z-direction, as inFIGS.7and8. This offset rotational alignment of the resistive elements505may be confirmed by comparing their relative alignments of the resistive elements505, in the z-direction as shown inFIGS.7and8with a reference point146aassigned on the circumference of the gear146as it rotates 360 degrees around the common gear axis CAX.

The rotation of the body portion502of the second potentiometer501about the common gear axis CAX relative to the body portion of the body portion502of the first potentiometer500, as illustrated inFIGS.7and8, may be defined in terms of the number of degrees of rotation as it relates to a Cartesian coordinate system. Accordingly, inFIG.7A-7C, the x-axis in a Cartesian coordinate system is illustrated as right and left, the y-axis in a Cartesian coordinate system is illustrated as up and down, and the z-axis may be defined as into and out of the page. The up position may be designated at 0 degrees, with the down position at 180 degrees, and with the right and left positions at 90 and 270 degrees, respectively. By way of example, the rotation the body portion502of the first potentiometer500one-hundred eighty degrees about the common gear axis CAX relative to the second potentiometer501(or vice versa) and fixing the body portion502in that configuration, such as shown inFIGS.7A-7C, results in the terminal portions503,504,506of the respective potentiometers500,501being positioned 180 degrees rotationally offset from one another (as shown inFIGS.7A-7C, the terminal portions503,504,506of potentiometer500are positioned at 180 degrees while the terminal portions503,504,506of potentiometer501are positioned at 0 degrees). By way of a second example, as shown inFIG.8, rotating the first potentiometer500ninety degrees counterclockwise relative to the second potentiometer501about the common gear axis CAX, and fixing the body portions502in that configuration, results in the terminal portions503,504,506of the respective potentiometers being positioned 90 degrees rotationally offset from one another (as shown inFIG.8, the terminal portions503,504,506of potentiometer500are positioned at 0 degrees while the terminal portions503,504,506of potentiometer501are positioned at 90 degrees). It should be appreciated that other rotational offsets of the potentiometers500,501relative to one another about the common gear axis CAX are also contemplated, so long as the offset is sufficient to ensure that at least one wiper arm508of at least one of the potentiometers500,501is in contact with its resistive element505. In certain embodiments, the gap511between the terminal portions503,504corresponds to about 30 degrees of rotational offset, and accordingly the rotational offsets may be anywhere from 30 to 330 degrees relative to one another, such as 45 degrees, 60 degrees, 75 degrees, 105 degrees, 120 degrees, 150 degrees, 210 degrees, 270 degrees, etc.

To do the comparison of the rotational offset of the respective elements505of the pair of potentiometers500,501, the reference point146ais assigned to a relative position on the gear146. For ease of description and illustration, as provided inFIGS.7A, the reference point146ahas been assigned to a position on the gear146corresponding to the intersection of the resistive element505and the first terminal portion503on the first potentiometer500when viewed from the z-direction. The gear146, for illustrative and description purposes, can be subdivided into a first arcuate region146band a second arcuate region146c, which together sum to 360 degrees of rotation (i.e., one full revolution of the gear146). The first arcuate region146bcorresponds the arcuate length AL of the resistive element505of the first potentiometer500when viewed in the z-direction, while the second arcuate region146ccorresponds to the additional arcuate length AAL associated with the gap511of the first potentiometer when viewed in the z-direction. The first and second arcuate regions146b,146c, being static reference regions, do not rotate as the gear146and the reference point146arotates about the common axis CAX, but maintain fixed coordination with the static arcuate length AL of the resistive element505and additional arcuate length AAL of the gap511of the first potentiometer500.

As the gear146rotates about the common gear axis CAX in a first rotational direction, the reference point146acorrespondingly rotates along an angular path of rotation AR (i.e., an arcuate path of rotation) about the common gear axis CAX through the first arcuate region146band the second arcuate region146cfor every full revolution of the gear146. As such, depending upon the relative amount of rotation of the gear146in the first rotational direction, the reference point146ais either positioned in the first arcuate region146bor the second arcuate region146cat all times as the gear146rotates 360 degrees about the common gear axis CAX in the first rotational direction.

Referring first toFIG.7A, the gear146is positioned such that the wiper arm508of the first potentiometer500is positioned at the intersection of the resistive element505and the terminal portion503. At the same time, the wiper arm508of the second potentiometer501is positioned on the resistive element505at a point between the first and second terminal portion503,504. In this position, the reference point146ais in the first arcuate region146bof the gear146, and both wiper arms508generate output signals to the controller78through the third terminal portion506by virtue of their electrical connection to the respective resistive element505, but wherein the scale of the respective output signals is different (assuming that the first reference signal provided through the first terminal portion503of each potentiometer500,501is the same) due to the positioning of the respective wiper arms508relative to their first and second terminal portions503,504.

InFIG.7B, the gear146has rotated such that the positioning of the wiper arm508of the first potentiometer500is located at the intersection of the resistive element505and the second terminal portion504and such that the positioning of the wiper arm508of the second potentiometer is nearer to the first terminal portion503than inFIG.7A. In this position, the reference point146ais still in the first arcuate region146bof the gear146(but at a different relative position than inFIG.7A), and both wiper arms508generate output signals to the controller78through the third terminal portion506by virtue of their electrical connection to the respective resistive element, but wherein the scale of the respective output signals is different from the respective scales inFIG.7A.

InFIG.7C, the gear146has rotated such that the positioning of the wiper arm508of the first potentiometer500is located within the gap511and such that the positioning of the wiper arm508of the second potentiometer501is along the resistive element505in a position closer to midway between the first and second terminal portions503,504. In this position, the reference point146ais in the second arcuate region146cof the gear146, and only the wiper arm508of the second potentiometer501generates an output signal to the controller78through the third terminal portion506, but wherein the scale of the respective output signal is different from the respective scales inFIGS.7A and7B. Further, the output signal of the first potentiometer500is interrupted, because there is no electrical contact between the wiper arm508and the resistive element505, resulting in an open, floating condition giving a high (mega-ohm) impedance. As such, the controller78receives only an output signal from the second potentiometer501(and either receives an interrupted signal, or no signal, from the first potentiometer500).

While not illustrated, when the gear146is rotated such that the wiper arm508of the second potentiometer501is within the gap511(i.e., between the terminal portions503,504along the top ofFIGS.7A-7C, the wiper arm508of the first potentiometer500is located approximately midway between the first and second terminal portions503,504along the resistive element505, and the reference point146ais positioned in the first arcuate region146b. Here, the output signal of the second potentiometer501is interrupted, because there is no electrical contact between the wiper arm508and the resistive element505. As such, the controller78receives only an output signal from the first potentiometer500of approximately one-half of the first reference signal provided through the first terminal portion503(and either receives an interrupted signal, or no signal, from the second potentiometer501).

AsFIGS.7A-7Cillustrate, at each and every potential reference point146aposition as the gear146rotates 360 degrees, at least one of the wiper arms508of the respective potentiometers500,501is electrically connected to its respective resistive element505. Accordingly, at each and every reference point position, a respective output signal is generated and sent to the controller78which can be used to determine the relative depth of the bore in the workpiece formed by the drill bit, as will be described further below.

Still further,FIGS.7A-7Cconfirm that when the reference point146ais in the first arcuate region146b, regardless of its relative position within the first arcuate region146b, the wiper arm508of the first potentiometer500is in electrical contact with its respective resistive element505. Also,FIGS.7A-7Cconfirm that when the reference point146ais in the second arcuate region146c, regardless of its relative position within the second arcuate region146c, the wiper arm508of the second potentiometer501is in electrical contact with its respective resistive element505. In other words, in the configuration ofFIGS.7A-7C, at least one wiper arm508of the respective pair of potentiometers500,501is always in contact with its respective resistive element505, regardless of the positioning of the reference point146ain either the first or second arcuate regions146b,146c.

InFIG.8, the body portion502of the second potentiometer501is rotated 90 degrees relative to the body portion502of the first potentiometer500(as opposed to 180 degrees as inFIGS.7A-7C). Similar to the arrangement ofFIGS.7A-7C, the amount of rotation of the second potentiometer501relative to the first potentiometer500is sufficient to ensure that the gap511of the second potentiometer501is not aligned with the gap511of the first potentiometer500.

Accordingly, as illustrated in the embodiments herein, in order to accomplish this stacking effect with the rotationally offset resistive elements505, the potentiometers500,501are coupled to the gear shaft147such that their body portions502are coupled to the housing portion138are rotationally offset sufficiently to ensure that the gap511of the second potentiometer501is not aligned with the gap511of the first potentiometer500. In other words, if the arcuate length AL of the resistive element505of each of the first and second potentiometers500,501is 11πr/6 (and hence the gap511is πr/6), the rotated positioning of the body portion502of the second potentiometer501between 30 and 330 degrees (which correlates to between πr/6 and 11πr/6) about the common gear axis CAX ensures that gaps511of the first and second potentiometers500,501do not overlap when another when viewed from the z-direction.

Stated another way, whileFIGS.7and8illustrate the body portions502of the pair of potentiometers500,501, rotated at 180 and 90 degrees offset from one another, other rotational offsets of the potentiometers500,501are contemplated. Specifically, the body portions502of the pair of potentiometers500,501may be offset from 30 to 330 degrees about the common gear axis CAX, and fixing the body portions502in that configuration, which ensures that at least one of the wiper arms508(rotating in coordination with one another) is contacting its respective resistive element505at all relative positions of the reference point146aof the gear146. In other words, through the use of two paired potentiometers500,501as described above, represented in two embodiments inFIGS.7and8, at least one of the pair of potentiometers500,501will be in the non-floating condition at all times, regardless of the rotational positioning of the wiper arms508of the potentiometers500,501, and thus is capable of providing a valid reading that can be used by the controller78to determine the bore depth as can be determined according to the method described below. It is of course possible to use three or more potentiometers in this manner as well.

Referring next toFIGS.9and10, a method for determining a bore depth in a workpiece formed by a drill bit66in the drill60as described above is also provided. In general, as illustrated inFIG.9, the logic700for determining the bore depth includes three basic steps. First, in Step702, the drill60is positioned against the workpiece. In particular, the drill60is positioned such that the cutting tip portion70at distal end180of the drill bit66is placed against the workpiece. Next, in Step704, the drill60is actuated to advance the cutting tip portion70of the drill bit66into the workpiece to form a bore, or hole, having a bore depth. As a part of Step704, the controller78directs the power source to send a first reference signal (typically in the form of a reference voltage), through the first terminal portion503to each of the respective resistive elements505of the potentiometers500,501. Finally, in Step706, the bore depth is determined via the controller78by determining the total amount of movement of the probe relative to the housing during Step704. Step706can be determined after completion of the drilling of the hole, by the drill60, or can be determined at any point in time as the hole is being drilled, with the instantaneous bore depth being determined and continuously updated.

InFIG.10, the details of the logic of Step706are described in further detail. First in Step708, the controller78determines the initial, or first, rotational position of the reference point146aof the gear146, in certain cases, prior to said step of actuating the drill60. In particular, the initial rotational position of the reference point146aof the gear146can be determined based upon the respective positioning of the at least two wiper arms508as the drill60is positioned against the workpiece in Step702prior to the actuation of the drill60in Step704. In this position, an initial respective signal(s) is generated from at least one of the at least two wiper arms508, with each signal scaled to their respective positioning on the resistive element505as a function of the respective provided first reference signal. The controller78receives the initial respective signal(s) and determines the initial respective position of the reference point146aof the gear146on the basis of the received initial respective signal(s). To aid in determining the initial respective position of the reference point, the memory of the controller78includes stored information regarding the size of the gear146and includes a pre-stored algorithm that can interpret the scale of the received initial inputs signal(s) and identify the relative positioning of the reference point146aof the gear146corresponding to the scale of the received initial inputs signal(s).

In Step710, the controller78determines a number of full rotations of the gear146in a single rotational direction about the common gear axis CAX with the at least two potentiometers500,501during, or after, said step of actuating the drill.

More specifically, the controller78determines a number of distinct interrupted signals generated from the wiper arm508of one, or both, of the potentiometers500,501during Step710. Each interrupted signal occurs when the gear146is rotated in the single rotational direction such that the reference point146aof the gear146is within the second arcuate region146csuch that the wiper arm508of a designated one or both of the potentiometers500,501(typically the first potentiometer500) is within the gap511. The end of one interrupted signal occurs when the gear146is further rotated in the single rotational direction such that the wiper arm508initiates contact with the resistive element505at the location corresponding to the first terminal portion503, or the second terminal portion504, depending upon which direction the wiper arm508is rotating about the common gear axis CAX.

In Step712, the controller78determines a final, or second, rotational position of the reference point146aof the gear146after Step704or at any point during step704. In particular, the final rotational position of the reference point146aof the gear146can be determined based upon the respective positioning of the at least two wiper arms508after the actuation of the drill is terminated. In this position, a final, second respective signal is generated from at least one of the at least two wiper arms508, with each signal scaled to their respective positioning on the resistive element505as a function of the respective provided first reference signal. The controller78receives the final, second respective signal(s) and utilizes the algorithm stored in the memory of the controller78to determine the final respective position of the reference point146aof the gear146on the basis of the received final, second respective signal(s).

In Step714, the controller78determines a change in the rotational position of the reference point146aof the gear146between said determined initial, first rotational position of Step710and said determined, second final rotational position of Step712. More specifically, the controller78compares the received initial, first respective signal(s) and the received final, second respective signal(s) and calculates the change in positioning based on the compared signals utilizing an algorithm stored in the memory of the controller78.

Finally, in Step716, the controller78determines the bore depth from the determined number of full rotations of the gear146occurring during Step712and from the determined change in the rotational position of the reference point146aof the gear146in Step714. More specifically, the controller78utilizes an algorithm stored in its memory that calculates the relative amount of movement of the probe100relative to the housing130on the basis of the determined number of interrupted signals and on the determined change in the rotational position of the reference point146aof the gear146and further calculates the bore depth on the basis of the determined relative amount of movement. As a part of Step716, the controller78may send an output signal to the display148, which provides a reading on the display corresponding to the bore depth that is visible by the operator of the drill60.

In each of the Steps for the logic700ofFIG.10, the controller78may be configured to determine the initial, first and final, second positioning of the reference point146aof the gear146on the basis of any single one received initial respective signal, and any single one received final respective signal, or on the basis of both received initial respective signals or both received final respective signals (i.e., based on the combined received initial respective signals or combined received final respective signals, when both of the wiper arms508are in contact with the respective resistive elements505corresponding to the initial and final respective position of the reference point146a), to determine the initial and final positioning of the reference point146aof the gear146.

In still further embodiments, the controller78is configured to configured to continually process generated signals from received from each of the potentiometers500,501during Step710to continually determine the respective positioning of the reference point146aof the gear146. In this regard, the controller78may utilize the received signal from one of the potentiometers500or501as the primary signal to continually determine the relative positioning of the reference point146aof the gear146, and only utilizing the signal received from the second one of the potentiometers500or501when the primary signal is in the interrupted state (i.e., where the wiper arm508of the designated one of the potentiometers500or511is positioned within the gap511).

Still further, the controller78may be configured to determine the number of complete revolutions of the gear146on the basis of the number of interrupted signals from a respective one of the potentiometers500or501, or on the basis of the number of interrupted signals from both of the potentiometers500,501.

In further embodiments, as opposed to having a pair of potentiometers500,501stacked in the z-direction as illustrated inFIGS.7and8, the potentiometers500,501, could be positioned side-to-side in the x-direction. For example, an additional gear (not shown) could be meshed with the gear146. A gear shaft from the additional gear could then be coupled to the rotor portion307of the second potentiometer501. The rotation of the gear146would in turn rotate the additional gear, and both wiper arms508of the first and second potentiometers500,501would rotate as described above. In a manner similar to the embodiments ofFIGS.7and8above, by positioning the body portion502of the second potentiometer501such that at least one of the wiper arms508is always in contact with its respective resistive element505

The surgical system60described herein provides a method for accurately measuring the bore depth in a workpiece formed by the drill bit66of the drill while also addressing the deficiencies with surgical drills utilizing a single potentiometer. Specifically, by utilizing at least two potentiometers which are configured such that at least one of the wiper arms is in contact with its respective resistive element regardless of the positioning of the reference point of the gear, the floating condition can be avoided. Still further, the inclusion of the at least one additional potentiometer makes it unnecessary to increase the diameter of the gear size to ensure that the gear, and the coupled single turn potentiometer, do not turn such that the wiper arm is positioned within the gap. This overcomes the further deficiencies of surgical drills having a single potentiometer in terms of undesirable bulk to the drill and potential obstruction of the surgeon's field of vision during the drilling operation.

It should be appreciated that the system described herein may be used for non-surgical applications, such as through drilling through workpieces other than tissue, such as wood, metal, or plastic. Additionally, it should be appreciated that the system may be used in conjunction with end-effectors other than drill bits.

Several configurations have been discussed in the foregoing description. However, the configurations discussed herein are not intended to be exhaustive or limit the disclosure to any particular form. Other configurations are specifically contemplated. For example, while the use of at least two potentiometers in the transducer assembly are described herein in which the first of potentiometers is incapable of detecting a reference point in the second arcuate region of the gear is described above but wherein the second potentiometer does detect the reference point in the second arcuate region, it is contemplated additional potentiometers, and not a single pair of potentiometers, may be utilized such that at least one potentiometer is able to detect a rotational position of the reference point of the gear at all positions within the first and second arcuate regions. Moreover, while the potentiometers or rotational sensor devices described above are typically of the same design, potentiometers or rotational sensor devices of different types or sizes may be utilized. Still further, other types of sensor devices located on the surgical drill, such as Hall sensors or the like, may be utilized in conjunction with the rotational sensors described herein that could provide enhanced precision for measurement. Even still further, it is contemplated that separate gears could be independently coupled to the probe, with each of the separate gears coupled to one, or more than one, potentiometer, and configured to ensure precise measurement of the bore depth and each possible probe position relative to the housing in accordance with the configuration of rotational sensor devices as described above. Still further, while the configurations for the transducer assemblies described above are specifically illustrated with respect to a removable measurement module, it is contemplated that the transducer assembly including the gear and sensor device may be included on a non-removable portion of the surgical drill.

The terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings and the disclosure may be practiced otherwise than as specifically described.

It will be further appreciated that the terms “include,” “includes,” and “including” have the same meaning as the terms “comprise,” “comprises,” and “comprising.” Moreover, it will be appreciated that terms such as “first,” “second,” “third,” and the like are used herein to differentiate certain structural features and components for the non-limiting, illustrative purposes of clarity and consistency.

The disclosure is intended to be defined in the independent claims, with specific features laid out in the dependent claims, wherein the subject-matter of a claim dependent from one independent claim can also be implemented in connection with another independent claim.

The present disclosure also comprises the following clauses, with specific features laid out in dependent clauses that may specifically be implemented as described in greater detail with reference to the configurations and drawings above.

I. A measurement module configured for releasable attachment to a surgical instrument, said measurement module comprising:a housing;a measurement cannula;a transducer assembly including a gear coupled to said measurement cannula and configured to rotate more than 360 degrees about a gear axis upon the movement of said probe relative to said housing, said gear having a reference point having an angular path of rotation about said gear axis being divided into a first arcuate region and a second arcuate region, said first arcuate region being separate from said second arcuate region; anda transducer comprising at least two potentiometers, each of said at least two potentiometers coupled to said gear,a first of said at least two potentiometers configured to detect a rotational position of said reference point in said first arcuate region and a second of said at least two potentiometers configured to detect said rotational position of said reference point in at least said second arcuate region, said first rotational sensor being incapable of detecting said reference point in the second arcuate region.

II. A measurement module configured for releasable attachment to a surgical instrument, said measurement module comprising:a housing;a measurement cannula;a transducer assembly including:a gear coupled to said measurement cannula and configured to rotate more than 360 degrees about a gear axis upon the movement of said measurement cannula relative to said housing, said gear having a reference point having an angular path of rotation about said gear axis being divided into a first arcuate region and a second arcuate region, said first arcuate region being separate from said second arcuate region; anda transducer comprising at least two rotational sensor devices, each of said at least two rotational sensor devicess fixed rotationally relative to said gear,a first rotational sensor device configured to detect a rotational position of said reference point in said first arcuate region and a second rotational sensor device configured to detect said rotational position of said reference point in said second arcuate region, said first rotational sensor device being incapable of detecting said reference point in the second arcuate region, said at least two rotational sensor devices each being adapted for independently generating a output signal corresponding to said detected rotational position of said reference point in said respective first and second arcuate region:a controller configured to receive each of said independently generated output signals and, based on each of said independently generated output signals, determine the depth of the bore in the tissue formed by the drill bit.

III. A transducer assembly for use with a surgical tool having a probe and a housing, said transducer assembly comprising:a gear coupled to the probe and configured to rotate more than 360 degrees about a gear axis upon the movement of the probe relative to the housing, said gear having a reference point having an angular path of rotation about said gear axis being divided into a first arcuate region and a second arcuate region, said first arcuate region being separate from said second arcuate region; anda transducer comprising at least two potentiometers, each of said at least two potentiometers coupled to said gear,a first of said at least two potentiometers configured to detect a rotational position of said reference point in said first arcuate region and a second of said at least two potentiometers configured to detect said rotational position of said reference point in at least said second arcuate region, said first potentiometer being incapable of detecting said reference point in the second arcuate region.