User interface device for surgical simulation system

A user interface device for a surgical simulation system, comprising a rigid shaft pivotably supported by a frame, and movable in the axial direction but fixed with respect to rotation around its longitudinal axis, and a handle having a sensor body rigidly attached to said rigid shaft, and a grip portion rotatable around said longitudinal axis relative said sensor body. The handle further comprises a rotator sleeve rotatable around said longitudinal axis relative said sensor body and said grip portion, a rotation sensor adapted to detect rotation of said rotator sleeve in relation to said sensor body, and a signal interface mounted on said sensor body and connected to receive a first detection signal from said rotation sensor. Through this design, all sensor elements and electronic circuitry can be provided in or adjacent to the sensor body, leading to an efficient design and manufacturing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 National Phase of PCT/EP2013/075000, filed on Nov. 28, 2013, which claims the benefit and priority of European Patent Application EP 12195067.9, filed on Nov. 30, 2012. The entire disclosures of each of the above applications are incorporated herein by reference.

FIELD

The present disclosure relates to a haptic user interface device for a surgical simulation system, and in particular a user interface device for simulating a laparoscopic procedure.

BACKGROUND

In recent years, systems for surgical simulations have become increasingly more used, in order to train physicians various surgical procedures without putting live patients at risk. In particular in the field of minimally-invasive surgery, such as laparoscopy, endoscopy, colonoscopy, etc., such simulation systems have gained significant acceptance. During minimal-invasive surgery the physician typically relies on an image on a screen rather than on an actual view of the patient, and with powerful image rendering available today, such an image can be simulated with a very high degree of realism.

In order to interact with the simulation software, the simulation system further requires an input device, i.e. hardware which the physician may operate and which simulates an actual surgical instrument. Such input devices should in physical appearance and function resemble an actual instrument. However, they must also provide sensor for detecting the current position of the simulated instrument, thereby enabling the simulation software to provide an appropriate image on the screen. In addition, such devices preferably include haptic feedback, i.e. provide feedback of forces that would be encountered during an actual procedure.

In the case of laparoscopy, an example of an input device is the Virtual Laparoscopic Interface (VLI) from Immersion Corp. This device includes a rigid shaft, corresponding to the instrument portion to be inserted into a patient, and a handle, with which the physician can move the instrument. In order to simulate the degrees of freedom of an actual instrument, which passes into a patient body through a small opening, the shaft is supported by a frame in a pivoting point with two degrees of freedom (rotation α, β). In addition, the shaft can be translated in linear motion along its longitudinal axis, i.e. in and out of a simulated body, as well as rotated around this longitudinal axis. The handle further includes a grip portion, allowing the physician to operate a simulated surgical tool at the tip of the instrument. The input device contains sensors for all degrees of freedom including rotation of the shaft. Most sensors are provided in vicinity of the pivoting point, except the sensor of grip action, which is detected in the handle and provided through a separate signal interface on the handle. This signal interface is thus movable in relation to the frame, and connected to the frame with a cord. Just as in an actual instrument, the grip portion may further be rotated in relation to the rest of the handle, corresponding to an adjustment of the grip in relation to the working position. Such adjustment is not detected by sensors, and does not result in any force feedback.

Another example from Immersion Corp. is the Laparoscopic Surgical Workstation, (LSW). Just as in the VLI, the shaft will rotate when the handle is rotated, requiring detection of rotation in the pivoting point. However, in this case it is the grip portion that is fixedly attached to the shaft. In order to enable adjustment of the grip position, a rotatable sleeve is arranged in front of the grip portion, and rotation of this sleeve relative the handle is detected separately. Moving the grip (and the entire handle) in relation to the sleeve will thus rotate the shaft, but the relative rotation between grip and sleeve will be detected, so that the simulation software can interpret this as a grip adjustment rather than actual instrument rotation. Grip action is detected in the grip portion similar to the VLI. The LSW is a haptic device, i.e. it has actuators arranged to provide force feedback in all degrees of freedom. In terms of force feedback, rotating only the sleeve (which does not rotate the shaft) and rotating the entire handle (including the sleeve and the shaft) will result in the same force feedback.

Yet another example is the Laparoscopic Impulse Engine (LIE), also from Immersion Corp. In this example, the shaft has a rotationally fixed exterior tube which does not rotate. Instead, the handle rotates in relation to the tube, and this motion is transferred by an axle extending inside the tube to the distal end of the shaft, where it is detected by a rotation encoder. Detection of grip action is done similar to the LSW mentioned above, by a sensor provided on the upper side of the grip portion. The LIE therefore also requires two signal interfaces on the moving parts of the device, one in the distal end of the shaft, and one on the grip portion. Each of these interfaces needs to be connected to the frame with a cord.

A relevant patent documents in this context are U.S. Pat. No. 6,323,837 and U.S. Pat. No. 6,902,405.

Despite the many user interfaces that are already available, these solutions are mechanically and electrically complex, typically with electric circuitry distributed between several locations. Also, they fail to correctly mimic an actual surgical instrument, such as a laparoscope, due to multiple cables connected to the device, and in some cases cables connected to the grip portion.

SUMMARY

It is an object of the present disclosure to address the shortcomings of the prior art, and to provide an improved user interface device which is robust in function and cost effective to manufacture. Another object is to provide a user interface device which in use provides the user with an experience more closely resembling that of an actual surgical instrument.

According to the disclosure, these and other objects are achieved with a device comprising a rigid shaft having a primary extension along a longitudinal axis, the rigid shaft being pivotably supported by a frame, and movable in relation to the frame in the axial direction, but being fixed in relation to the frame with respect to rotation around the longitudinal axis, and a handle having a sensor body rigidly attached to the rigid shaft, and a grip portion rotatable around the longitudinal axis relative the sensor body, the grip portion being adapted to transform a gripping motion of a user into a linear displacement. The handle further comprises a rotator sleeve rotatable around the longitudinal axis relative the sensor body and the grip portion, a rotation sensor adapted to detect rotation of the rotator sleeve in relation to the sensor body, and a signal interface mounted on the sensor body and connected to receive a first detection signal from the rotation sensor.

Features of this design are 1) a shaft which is fixed with respect to rotation around its longitudinal axis, and 2) a handle which has a sensor body which is fixedly attached to the shaft, and a rotator sleeve which is rotatable relative to the sensor body. The combination of these features has not been previously disclosed, and provides several advantages compared to prior art user interface devices.

To begin with, all sensor elements and electronic circuitry can be provided in or adjacent to the sensor body, leading to an efficient design and manufacturing. Further, the signal interface, which also is provided on the sensor body, will be subject to translational movement, but not to any rotational movement around the longitudinal axis of the shaft. This reduces the amount of shear stress and wear on any cables or wiring connected to the signal interface, improving lifetime of the user interface device.

According to an embodiment, the handle further comprises a linear sensor mounted in the sensor body, and a displacement transfer arrangement for transferring any linear displacement generated in the grip portion to the linear sensor, wherein the signal interface is connected to receive a second detection signal from the linear sensor.

According to this embodiment, also grip action can be detected in the sensor body, so that no sensor circuitry is required in the grip portion. The grip portion can thus be a purely mechanical device, facilitating manufacture of the handle.

Further, as only one single signal interface is required (from the sensor body), only one cable or wire is required. In particular, the grip portion is completely free from cables or wiring.

In embodiments, the user interface device is arranged to provide haptic feedback to a user. For this purpose, a plurality of actuators may be mounted on the frame to provide force feedback when the shaft and handle are rotated or translated relative the frame. Typically, force feedback is provided in at least one linear and two rotational degrees of freedom.

Further, an actuator arranged to provide force feedback around a first axis (B) can advantageously be mounted on a part of the frame that rotates with said handle around a second axis (A). This means that a force transfer means, such as a drive belt or wire, extending between the actuator and the first axis will run in a fixed path, i.e. will not be subject to torsion or twist. This arrangement of force feedback actuators on the frame of a user interface device for a surgical simulation is considered to be novel and inventive per se, also without limitation to the features of the first teaching of the present disclosure.

The rigid shaft may have a rack on one side, which rack engages a gear wheel on said frame, thereby transforming a linear motion of the shaft into a rotation of the gear wheel. This design can be an effective way to enable detection of the shaft position, as well as force feedback by an actuator connected to the gear wheel.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1shows a user interface device1according to an embodiment of the present disclosure, schematically connected as part of a simulation system2.

The simulation system2comprises a processing unit3running simulation software for simulating a surgical procedure, and a display4for displaying a visualization of the simulated procedure to a user. The interface device1is connected to the simulation system, and allows a user to provide input to the system2, thereby interacting with the simulation visualized in the display device. The interface illustrated here is a haptic rig, i.e. it is adapted to provide a user with force feedback from the simulation in at least some of the degrees of freedom of the interface. It is noted that the disclosure is not limited to a haptic interface, but is also applicable to a non-haptic interface.

The user interface device1, comprises a movable instrument10pivotably suspended by a frame11. The frame11allows rotation of the instrument10around a first axis A and a second axis B, typically orthogonal to the first axis A.

FIG. 2very schematically shows some parts of the user interface device1inFIG. 1, in order to illustrate the various degrees of freedom in the frame11. Note that the handle120inFIG. 2is different from the handle20inFIG. 1.

In the illustrated embodiments, rotation around the first axis A is provided close to the stationary base12of the frame, by a disc13rotatably mounted to the base12. A first actuator, such as a electric motor14, is also mounted to the base12, and arranged to transfer a torque to the disc13. As illustrated schematically inFIG. 2, this can be accomplished by a driving belt7arranged around the disc13and the motor axle. By operation of the motor14, force feedback can be provided in movement around the axis A. A rotation sensor (not shown) is provided to detect the position of the disc13in relation to the base12. The sensor may advantageously be a rotational encoder integrated in the motor14, and arranged to detect rotation of the motor axis.

Rotation around the second axis B is provided in a distal end15aof the neck15of the frame11. The neck15and its distal end15aare fixedly mounted on the disc13, and will thus rotate with the disc when the frame is rotated around the axis A. A suspension portion16is mounted on the distal end15aso as to be rotatable around axis B. The suspension portion16is arranged to suspend the handle10, and the details of this suspension will be discussed below. A second electric motor17is mounted on the neck15, and is arranged to transfer a torque to the suspension portion16. As illustrated schematically inFIG. 2, this can be accomplished by a driving belt8arranged around the portion16and the motor axle. By operation of the motor17, force feedback can be provided in movement around the axis B. A rotation sensor (not shown) is provided to detect the position of the suspension portion16in relation to the distal end15aof the neck15. The sensor may advantageously be a rotational encoder integrated in the motor17, and arranged to detect rotation of the motor axis.

Primarily with reference toFIG. 2, it is noted that the motor17is mounted on the neck15, and thus will rotate together with the neck15and the suspension portion16around the axis A. The path of the drive belt8or drive wire loop extending between the axle of the motor17and the suspension portion16will thus be fixed in space, and will not be subject to any twist or torsion. This extends the life time of the belt8or wire.

It is noted that in the case of a non-haptic interface, in which case there are no actuators, sensors for detection of rotation around axis A and B is probably better provided directly on the axis A, B, e.g. on the disc13and the distal end15a.

Turning now to the instrument10, it comprises a handle20attached to the end of a rigid shaft21. The handle20has a sensor body22, fixedly connected to the shaft21, and a rotator sleeve23and a grip portion24which are both rotatable around the longitudinal axis C of the shaft21.

Just as in an actual instrument, rotation of the sleeve23represents rotation of the instrument. Any rotation of the rotator sleeve23in relation to the sensor body will thus be detected by a sensor in the sensor body22. The grip24and rotator sleeve23are coupled by a certain friction so that they are normally rotated together. However, a user may overcome the friction, to rotate the sleeve23and the grip24in relation to each other. Rotation of the grip24while the sleeve23is held fix merely represents an adjustment of the grip in relation to the instrument, and will not influence the simulated procedure. Rotation of the sleeve23in relation to the sensor body while the grip24is held fix, will however represent rotation of the instrument and will accordingly be detected by the sensor body.

The grip portion24allows the user to perform a gripping action using a scissor-like grip25, and this action will also be detected by a sensor in the sensor body22. A signal line26connects the sensor body22with the frame11, in the illustrated example with the distal end15aof the neck15. The signal line26enables communication of sensor signals from the sensor body22. The signal line is flexible, so as to allow movement of the instrument10in relation to the frame11.

In the illustrated embodiment, the interface device1is not adapted to provide any force feedback associated with rotation of the instrument around axis C. It is noted that there are typically very limited forces acting on an actual instrument in this degree of freedom when operated inside a body. However, if such feedback is nevertheless desired, it may be accomplished by coupling a force to the rotation of the sleeve23relative the sensor body. As a simple example, a passive variable brake can be provided to the sleeve23. Such a brake would introduce a resistance to turning the sleeve, and this resistance can be variable depending on the simulation. Of course, also active force feedback can be envisaged with a suitable actuator, such as an electric motor. It is however important that such actuator, if mounted on the handle, is not too heavy or bulky, as it could otherwise impact negatively on the user experience.

The rigid shaft21is mounted to the suspension portion16of the frame11so as to be movable along the longitudinal axis C. A third electric motor27is mounted to the suspension portion16to transfer a force along the axis C to the shaft21. By operation of the motor27, force feedback can thus be provided along the axis C. A sensor (not shown) is provided in the suspension portion16to detect linear motion of the shaft in relation to the portion16. In the illustrated example, the shaft21is provided on one side with a rack28which engages a gearwheel29on the end of a motor shaft. Any linear motion of the shaft21will thus effectively be converted into rotational motion, to which a torque can be applied by the motor27. Detection of the linear motion is also facilitated, and the sensor may be a rotational encoder integrated in the motor17, and arranged to detect rotation of the motor axis

The base12of the frame11is mounted to a control unit30, which includes drive circuitry31and communication interface32, typically mounted on a printed circuit board33. The control unit30can be incorporated in a working table (not shown). The interface32is connected to receive sensor signals from the various sensors in handle10and frame11, and to communicate these signals to the simulation system2. The interface32is further connected to receive force feedback signals from the simulation system2, i.e. forces acting on the simulated instrument as a result of user actions. The drive circuitry31is connected to the interface32, and arranged to drive the motors14,17and27based on the force feedback signals from the simulation system. The interface32is here connected to the simulation system via a signal line34connecting a terminal35of the control unit30with the processing unit3of the simulation system. The connection may alternatively be wireless, e.g. Bluetooth or WiFi.

Details of the operation of the various parts of the handle, and in particular the sensor body, will now be discussed with reference toFIGS. 3 and 4showing two different handles according to embodiments of the present disclosure.

FIG. 3shows the handle inFIG. 1in more detail. Reference numeral40denotes a rotation encoder, such as an optic or magnetic encoder mounted in the sensor body22. The encoder40has a house41, and a central pin43extending out of the house. Rotation of the pin43in relation to the house41can be detected, and results in a sensor signal indicative of the rotation. The encoder40is here in electric contact with circuitry on a printed circuit board44, from which the sensor signal can be outputted via a terminal45. The pin43of the encoder40is rotationally coupled to the rotator sleeve23, which is rotatably connected to the sensor body22. Rotation of the sleeve23will thus rotate the pin43, and generate a sensor signal available at the terminal45.

The grip portion24comprises a mechanical arrangement to generate a linear motion in response to action of the scissors-like grip25. In the illustrated example, the rear part of the grip25ais pivotable and connected to displace an elongate member48along the axis C. This linear motion is transferred by a motion transfer arrangement to a linear sensor46in the sensor body22in electric contact with circuitry on the circuit board44. The linear sensor here includes a sliding potentiometer47, the resistance of which is converted into a sensor signal indicative of a displacement of the potentiometer. Activation of the grip25will thus generate a sensor signal available at the terminal45.

The motion transfer arrangement will be described in the following. The member48extends into the rotator sleeve23, where it is mechanically connected to a disc49which is slidable inside the rotator sleeve23along the C-axis (seeFIG. 1). The front end48aof the member48is connected to the disc49in such a way that forces along the C-axis are transferred between the member48and the disc49, while rotational forces around the C-axis are not transferred between the member48and the disc49. As an example of such a coupling, the member48is illustrated as having a magnet50in its front end48a, which magnet50is attracted to the central part of the disc49. A second elongate member51has one end51amechanically connected to the slidable potentiometer47, and another end51bconnected to the disc49. Similar to the end48aof the elongate member48, the end51bis connected to the disc49in such a way that forces along the C-axis are transferred between the member51and the disc49, while other forces are not transferred between the member48and the disc49. As an example of such a coupling, the member51is illustrated as having a magnet52in its end51b, which magnet52is attracted to the peripheral part of the disc49.

The motion transfer arrangement48,49,50,51,52operates in the following way. When the grip25is activated, the elongate member48is displaced along the C-axis. This displacement is transferred to the disc49, so that the disc49is displaced along the C-axis inside the rotator sleeve23. The displacement of the disc49is further transferred to the member51, which displaces the slide potentiometer47of the sensor46. When the linear displacement is towards the shaft21, the member48will simply abut against and push the disc49, which will abut against and push the member51, so that motion will be transferred by direct contact. When the linear displacement is away from the shaft21, the magnet50will attract the disc49, which will attract the magnet52, so that motion will be transferred by magnetic contact. When the grip portion24is rotated in relation to the sleeve23, the elongate member48will also rotate, but this rotation will not cause any (substantial) forces on the disc49. In the illustrated example, the magnet50will simply slip against the surface of the disc49. In a similar way, when the rotator sleeve23is rotated in relation to the sensor body22, the disc49will slide against the elongate member51, without transferring any (substantial) force.

FIG. 4shows a handle120according to a further embodiment of the disclosure. Similar to the handle20inFIG. 3, the handle120comprises a sensor body122fixedly connected to the shaft121, and a rotator sleeve123and a grip portion124, both rotatable around the longitudinal axis C of the shaft121. Compared to the embodiment inFIG. 3, the rotator sleeve123is more elongated, and extends outside the sensor body122so as to cover most of the sensor body.

Also in this embodiment, the sensor body122houses a rotation encoder140to detect rotation of the rotator sleeve123relative the sensor body. The encoder is here an optical encoder, and the sensor optics of the encoder140includes a light transceiver141arranged on the sensor body side, and a reflector disc143arranged on the sleeve side. Rotation of the reflector disc143can be detected and results in a sensor signal indicative of the rotation. The encoder140is here in electric contact with circuitry on a printed circuit board144, from which the sensor signal can be outputted via a terminal145. The disc143is fixed to the sleeve123, so that rotation of the sleeve123will generate a sensor signal which is available at the terminal145.

The grip portion124is similar to the grip portion24inFIG. 3, and has a scissor-like grip125which can be operated by a user to generate a linear motion. Also here, the rear part of the grip125ais pivotable and connected to displace an elongate member148along the axis C. This linear motion is transferred by a motion transfer arrangement to a linear sensor146in the sensor body122in electric contact with circuitry on the circuit board144. Also in this case the linear sensor includes a sliding potentiometer147, the resistance of which is converted into a sensor signal indicative of a displacement of the potentiometer. Activation of the grip125will thus generate a sensor signal available at the terminal145.

The motion transfer arrangement in the embodiment inFIG. 4is different from the arrangement inFIG. 3. In addition to the elongate member148, the arrangement here comprises a second elongate member149, aligned with the first elongate member148along the central axis C of the handle. The second elongate member149is coupled to the slide potentiometer147, and extends through a hole in the center of optical encoder (i.e. the transceiver141and the reflector disc143). The members148and149are mechanically connected such that forces along the C-axis are transferred between the members, while rotational torque is not transferred (to any significant degree). In the illustrated example, a magnet150is arranged on the end of member148, and is attracted to member149. The magnet150will connect the members148,149in the axial direction, while it will slip against the member149when the members148,149are rotated relative each other.

The person skilled in the art realizes that the present disclosure by no means is limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, other types of sensors and encoders may be used, for detection of rotation as well as translation. For example, hall effect sensors or piezoelectric sensors. Further, the torque transmission from motors14and17may comprise suitable gear transmission instead of belt drive.