Surgical Robotic System

Abstract

An instrument drive unit for use in a robotic surgical system includes: a carriage configured to be coupled to a robotic arm; a plurality of drive shafts rotatably supported in the carriage; a plurality of electric motors disposed around the plurality of drive shafts; and a plurality of drive gears. Each electric motor includes a stator and a rotor disposed within the stator. Each drive gear is fixed to a corresponding drive shaft and configured to interface with a corresponding driven member of an electromechanical surgical instrument. Each rotor is configured to rotate a corresponding drive gear in response to activation of a corresponding electric motor to actuate a function of the electromechanical surgical instrument.

Description

Background Art

[0001] Surgical robotic systems have been used for minimally invasive medical surgeries. Some surgical robotic systems include a console that supports a surgical robotic arm and a surgical instrument having at least one end effector (e.g., forceps or a grasping tool) mounted to the robotic arm. The robotic arm provides mechanical power to the surgical instrument to enable its operation and movement.

[0002] Manually operated surgical instruments typically include a handle assembly for actuating the functions of the surgical instrument. However, when a robotic surgical system is used, there is typically no handle assembly to actuate the functions of the end effector. Therefore, in order to use each unique surgical instrument with a robotic surgical system, an instrument drive unit is used to interface with the selected surgical instrument to drive the operation of the surgical instrument.

[0003] The instrument drive unit is typically coupled to the robotic arm via a slide. The slide allows the instrument drive unit and attached surgical instrument to move along the axis of the slide, thereby providing a means for adjusting the axial position of the end effector of the surgical instrument. Summary of the invention

[0004] According to aspects of the present disclosure, an instrument drive unit for use in a robotic surgical system is provided and includes: a carriage configured to be coupled to a robotic arm; a plurality of drive shafts rotatably supported in the carriage; a plurality of electric motors disposed around the plurality of drive shafts; and a plurality of drive gears. Each electric motor includes a stator and a rotor disposed within the stator. Each drive gear is fixed to a corresponding drive shaft and configured to interface with a corresponding driven member of an electromechanical surgical instrument. Each rotor is configured to rotate a corresponding drive gear in response to activation of a corresponding electric motor to actuate a function of the electromechanical surgical instrument.

[0005] In various aspects, each stator can be fixed relative to the carriage, and each rotor can rotate relative to and within the corresponding stator.

[0006] In other aspects, the electric motors can be stacked vertically within the carriage.

[0007] In some aspects, the instrument drive unit can further include a sleeve rotatably coupled to the distal end portion of the carriage. The sleeve can be configured to non-rotatably hold the electromechanical surgical instrument.

[0008] In one aspect, the instrument drive unit may include: a drive motor having a stator fixed within a carriage; and a rotor disposed within the stator of the drive motor and non-rotatably coupled to the sleeve. The rotor of the drive motor may be configured to rotate the sleeve about a central longitudinal axis defined by the carriage.

[0009] In one aspect, the instrument drive unit may further include a plurality of ring gears. Each ring gear may be fixed to a corresponding rotor and operably coupled to a corresponding drive gear.

[0010] In some aspects, each ring gear can be concentrically disposed within a corresponding rotor such that rotation of the rotor results in rotation of the corresponding ring gear.

[0011] In other aspects, the ring gears may be stacked vertically within the electric motor.

[0012] In one aspect, the first electric motor, the first ring gear, and the first drive gear may be operably coupled to one another and aligned along a first plane.

[0013] In various aspects, the second electric motor, the second ring gear, and the second drive gear may be operably coupled to one another and aligned along a second plane vertically displaced from the first plane.

[0014] In some aspects, the ring gears can rotate independently relative to each other.

[0015] In other aspects, the first gear ring can have gear teeth on its inner periphery.The gear teeth on the inner periphery of the first gear ring can interface with the corresponding drive gear, and the outer periphery of the first gear ring can be attached to the inner periphery of the corresponding rotor.

[0016] In one aspect, the drive gears may be vertically offset from one another.

[0017] In various aspects, each drive shaft may have a distal end portion configured for interfacing with a corresponding driven member of the electromechanical surgical instrument.

[0018] In some aspects, each drive shaft may have a series of idler gears rotatably disposed thereabout and vertically offset from one another. The series of idler gears may engage with corresponding ring gears to stabilize the drive shaft within the electric motor.

[0019] In another aspect of the present disclosure, an instrument drive unit for use in a robotic surgical system is provided, and the instrument drive unit includes: a carriage configured to be coupled to a robotic arm; a plurality of electric motors supported in the carriage; and a plurality of drive shafts arranged within the plurality of electric motors. Each electric motor includes a stator and a rotor disposed within the stator. The drive shaft is configured to interface with a corresponding driven member of an electromechanical surgical instrument. Each drive shaft has a drive gear fixed thereto. The drive gears are arranged at discrete vertical positions relative to each other. Each rotor is configured to rotate a corresponding drive gear in response to activation of a corresponding electric motor in the plurality of electric motors to actuate a function of the electromechanical surgical instrument.

[0020] In some aspects, the instrument drive unit can further include a plurality of vertically stacked ring gears, each ring gear being fixed to a corresponding rotor and operably coupled to a corresponding drive gear, such that each rotor is configured to rotate a corresponding drive gear in response to activation of a corresponding electric motor of the plurality of electric motors to actuate a function of the electromechanical surgical instrument.

[0021] Further details and aspects of exemplary embodiments of the present disclosure are described in more detail below with reference to the accompanying drawings.

[0022] As used herein, the terms parallel and vertical should be understood to encompass relative configurations of substantially parallel and substantially vertical that vary by approximately + or - 10 degrees from true parallel and true vertical. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Embodiments of the present disclosure are described herein with reference to the accompanying drawings, in which:

[0024] Figure 1 is a schematic diagram of a surgical robot system including an instrument drive unit coupled to a slide according to the present disclosure;

[0025] Figure 2 yes Figure 1 A perspective view of an instrument drive unit of a surgical robot system, showing a portion of a carriage of the instrument drive unit in dashed lines, the figure showing internal components of the instrument drive unit;

[0026] Figure 3 yes Figure 2 A front perspective view of a series of vertically stacked electric motors of an instrument drive unit;

[0027] Figure 4 is a perspective view with some of the electric motors and gear rings removed to reveal a plurality of drive shafts of the instrument drive unit; and

[0028] Figure 5 yes Figure 2 Side cross-sectional view of an instrument drive unit. DETAILED DESCRIPTION

[0029] Embodiments of the surgical robot system and its instrument drive unit disclosed in the present invention are described in detail with reference to the accompanying drawings, in which the same reference numerals refer to the same or corresponding elements in each of the several views. As used herein, the term "distal" refers to the portion of the surgical robot system or its components that is closest to the patient, and the term "proximal" refers to the portion of the surgical robot system or its components that is farther away from the patient. As used herein, the term "vertical" refers to a direction defined along the longitudinal axis of a portion of the surgical robot system, and the term "horizontal" refers to a direction defined along the transverse axis of a portion of the surgical robot system.

[0030] As will be described in detail below, an instrument drive unit of a surgical robotic system is provided that is configured to allow bottom loading of surgical instruments. The instrument drive unit has a plurality of drive shafts, each drive shaft being configured to be coupled to a corresponding driven member of a surgical instrument for performing a discrete function of the surgical instrument. The drive shafts of the instrument drive unit are operably coupled to a discrete electric motor of the instrument drive unit via a discrete transmission assembly. The configuration of the transmission assembly allows the overall height of the instrument drive unit to be reduced (e.g., the instrument drive unit is more compact). For example, the gears of the transmission assembly are vertically and horizontally offset from the gears of other transmission assemblies. Other features and benefits of the disclosed instrument drive unit are further described below.

[0031] First reference Figure 1 , a surgical system such as a surgical robot system 1 generally comprises: a plurality of surgical robot arms 2, 3; an elongated slide 13 coupled to the end of each of the robot arms 2, 3; an instrument drive unit 20 and an electromechanical instrument 10, both of which are detachably attached to the slide 13 and configured to move along the slide 13; a control device 4; and an operating console 5 coupled to the control device 4. The operating console 5 comprises: a display device 6, which is specifically configured to display a three-dimensional image; and manual input devices 7, 8, by means of which a person such as a surgeon (not shown) can remotely control the robot arms 2, 3 in a first operating mode, as is generally known to a person skilled in the art.

[0032] Each of the robot arms 2, 3 may consist of a plurality of components connected by joints. The robot arms 2, 3 may be driven by an electric drive (not shown) connected to a control device 4. The control device 4 (e.g. a computer) is arranged to activate the drive specifically by means of a computer program in such a way that the robot arms 2, 3, the attached instrument drive unit 20 and thus the electromechanical instrument 10 perform the desired movement according to the movement defined by means of the manual input devices 7, 8. The control device 4 may also be arranged in such a way that it regulates the movement of the instrument drive unit 20 along the slide 13, the movement of the robot arms 2, 3 and / or the movement of the drive.

[0033] The surgical robot system 1 is configured to be used on a patient "P" lying on an operating table "ST" to be treated in a minimally invasive manner with the aid of surgical instruments, such as electromechanical instruments 10. The surgical robot system 1 may also include more than two robotic arms 2, 3, the additional robotic arms also being connected to the control device 4 and being remotely controllable with the aid of an operating console 5. Surgical instruments, such as the electromechanical surgical instrument 10 (including an electromechanical end effector), may also be attached to additional robotic arms.

[0034] The control device 4 may control a plurality of motors, for example motors (motor 1 ... n), each of which is configured to drive the movement of the robot arms 2, 3 in a plurality of directions. In addition, the control device 4 may control a plurality of drive motors 22 ( Figure 2-5 ) to drive various operations of the surgical instrument 10. The instrument drive unit 20 transmits power and actuation force from its motor to a driven member (not shown) of the electromechanical instrument 10 to ultimately drive the movement of a component of an end effector of the electromechanical instrument 10, such as movement of a blade (not shown) and / or closing and opening of a jaw member of the end effector.

[0035] For a detailed description of the construction and operation of a robotic surgical system, reference may be made to US Patent No. 8,828,023, entitled “Medical Workstation,” the entire contents of which are incorporated herein by reference.

[0036] refer to Figure 2-5 The instrument drive unit 20 will now be described in detail. The instrument drive unit 20 includes a carriage 26 and a coupling or sleeve 28 rotatably coupled to a distal end portion 26b of the carriage 26 for moving the surgical instrument 10 ( Figure 1 ) is connected to the instrument drive unit 20. The carriage 26 of the instrument drive unit 20 is configured to be slidably coupled to the slide 13 ( Figure 1 ) is longitudinally defined by a linear track (not shown). The proximal portion 26a of the carriage 26 accommodates a plurality of electric motors 22a, 22b, 22c, 22d, 22d, 22e (collectively referred to herein as "22") for performing various functions of the attached surgical instrument 10.

[0037] The electric motor 22 of the instrument drive unit 20 is hidden in the carriage 26. The electric motors 22 are stacked vertically on each other and can be controlled via the control device 4 ( Figure 1) are independently actuated. One of the electric motors, such as the fifth electric motor 22e, is configured to achieve rotation of the surgical instrument 10 when the surgical instrument 10 is connected to the instrument drive unit 20, and the remaining electric motors 22a, 22b, 22c, 22d are configured to actuate the functions of the surgical instrument 10 as will be described. The electric motor 22 is an integrated AC motor. In an embodiment, the electric motor 22 can be any suitable type of electric motor, such as an AC brushless motor, a DC brushed motor, a DC brushless motor, a direct drive motor, a servo motor, a stepper motor, etc. It is contemplated and within the scope of the present disclosure that the electric motor 22 is in the form of a hollow motor, etc. Other types of motors are also contemplated. Although the instrument drive unit 20 is shown as having five electric motors, it is contemplated that the instrument drive unit 20 may have more or less than five electric motors. The electric motors 22 are interconnected to provide an unlimited range of motion along the longitudinal axis "X" of the instrument drive unit 20.

[0038] The electric motor 22 has stators 40a, 40b, 40c, 40d, 40e (collectively referred to herein as "40") fixed in the carriage 26, and rotors 42 (only rotors 42a and 42d are shown) rotatably arranged in the corresponding stators 40. Each stator 40 may be annular and stacked on top of each other to form a hollow cylinder, such as Figure 3 The stator 40 may be configured to receive current from a power source (not explicitly shown) to generate a rotating magnetic field that drives the rotor 42 to rotate.

[0039] Each rotor 42 may be configured as a permanent magnet, an electromagnet, or any other suitable conductor. The rotors 42 are stacked vertically within the hollow cylinder formed by the stator 40 and are independently rotatable relative to each other about a central longitudinal axis “X” defined by the motor 22 .

[0040] Continue to refer Figure 2-5 The instrument drive unit 20 further includes a plurality of ring gears 62a, 62d, a plurality of drive gears 64a, 64b, 64c, 64d (collectively referred to herein as "64"), and a plurality of drive shafts 66a, 66b, 66c, 66d (collectively referred to herein as "66"). Although only the ring gears 62a and 62d are shown, the instrument drive unit 20 has four ring gears for coupling the four drive gears 64 and the corresponding four rotors 42.

[0041] The gear rings 62a, 62d are stacked vertically within the electric motor 22. In particular, the gear rings 62a, 62d are coaxial along a central longitudinal axis "X" defined by the motor 22. Figure 5As best shown in FIG. 1 , each ring gear 62a, 62d has an outer periphery 70 adhered to an inner periphery 73 of a corresponding rotor 42 such that each ring gear and rotor pair (e.g., ring gear 62a and rotor 42a) rotates together relative to the corresponding stator 40a. Each ring gear 62a, 62d has gear teeth 68 extending from its inner periphery 72. As will be described, the gear teeth 68 on the inner periphery 72 of each ring gear 62a, 62d interface with the corresponding drive gear 64. In embodiments, each ring gear 62a, 62d may be configured as a rotor 42 rather than being integrally connected to the rotor 42.

[0042] The drive shafts 66a, 66b, 66c, 66d extend longitudinally through the motor 22 and extend distally therefrom. The drive shafts 66 each have a distal portion configured to be operably coupled to a driven member (not explicitly shown) of the surgical instrument 10. For example, the distal portion of each of the drive shafts 66 may have a coupler (e.g., a gear) for coupling with a corresponding coupler of the driven member of the surgical instrument 10. Thus, after the electromechanical instrument 10 is bottom-loaded into the instrument drive unit 20, the distal portions of the drive shafts 66 of the instrument drive unit 20 are operably coupled to the gears / couplers in the distal end of the main body portion (not shown) of the electromechanical instrument 10, so that rotation of each drive shaft 66 causes the correspondingly coupled driven member of the surgical instrument 10 to rotate to achieve discrete functions of the surgical instrument (e.g., opening / closing of the end effector, articulation of the end effector, etc.).

[0043] The drive shafts 66 each have a drive gear 64, such as a spur gear, rotationally fixed about them. Each of the drive gears 64 is positioned at a discrete vertical position on its respective drive shaft 66 such that the drive gears 64 are vertically offset from one another by a selected distance. Since the drive gears 64 are circumferentially spaced from one another in addition to being vertically offset, the drive gears 64 are offset from one another in all three dimensions. As mentioned above, the drive gears 64 each interface or intermesh with the gear teeth 68 on the inner periphery 72 of the corresponding ring gear 62 and receive torque therefrom originating from the respective rotor 42.

[0044] Each drive shaft 66 may have a nut 74a, 74b, 74c, 74d (collectively referred to herein as "74") fixed thereabout. The nut 74 is disposed adjacent to and fixed to the corresponding drive gear 64, thereby fixedly coupling the drive gear 64 to the drive shaft 66. Each drive shaft 66 may further include a series of idler gears 76 rotatably disposed thereabout and vertically offset from each other. The series of idler gears 76 on each drive shaft 66 interface with the corresponding ring gear 62 to stabilize the multiple drive shafts 66 within the multiple electric motors 22.

[0045] In operation, the electromechanical instrument 10 is coupled to the instrument drive unit 20 by passing the main body of the electromechanical instrument 10 in a proximal direction through the sleeve 28 of the instrument drive unit 20. With the main body of the electromechanical instrument 10 attached to the sleeve 28 of the instrument drive unit 28, the distal end portion of each of the drive shafts 66 interfaces with a corresponding gear / coupler (not shown) in the proximal end of the main body of the electromechanical instrument 10.

[0046] When the electromechanical instrument 10 is connected to the instrument drive unit 20, in order to actuate a specific function of the surgical instrument 10, such as opening or closing the end effector of the surgical instrument 10, one of the electric motors 22 of the instrument drive unit 20, such as the first electric motor 22a, is controlled by the control device 4 ( Figure 1 ) is activated. Activation of the first electric motor 22a includes supplying current to its stator 40a, which drives the rotation of its rotor 42a. It is contemplated that the control device 4 or processor (not shown) of the electric motor 22a generates a rotating magnetic field around the stator 40a to drive the rotation of the rotor 42a.

[0047] The first ring gear 62a rotates with the rotor 42a, which in turn rotates the first drive gear 64a. Since the first drive gear 64a is rotationally fixed about the first drive shaft 66a, and the distal end portion of the first drive shaft 66a is operably connected to the surgical instrument 10 ( Figure 1 ), so the rotation of the first drive gear 64a causes the first drive shaft 66a to rotate, thereby rotating the first driven member of the electromechanical instrument 10 to actuate the relevant functions of the surgical instrument 10.

[0048] In order to rotate the electromechanical device 10 about its longitudinal axis, the fifth electric motor 22e of the device drive unit 20 is controlled by the control device 4 ( Figure 1 ) is activated. Activation of the fifth electric motor 22e includes supplying current to its stator 40e, which drives the rotation of its rotor 42e. The rotation of the rotor 42e causes the sleeve 28 to rotate. With the electromechanical device 10 non-rotatably supported in the sleeve 28, the electromechanical device 10 rotates with the sleeve 28 relative to the carriage 26 to change the rotational orientation of the electromechanical device 10.

[0049] The drive motors 22a, 22b, 22c, 22d may be configured to simultaneously rotate the rotors 42a, 42b, 42c, 42d and, in turn, the drive gears 64a, 64b, 64c, 64d as the sleeve 28 rotates. This will prevent rotation of the drive shafts 66a, 66b, 66c, 66d relative to the ring gears 62a, 62b, 62c, 62d during rotation of the sleeve 28, which may otherwise occur if the drive gears 64a, 64b, 64c, 64d are allowed to rotate relative to the ring gears 62a, 62b, 62c, 62d during rotation of the sleeve 28. Conversely, the fifth motor 22e may be configured to counteract any torque output by the other four drive motors 22a, 22b, 22c, 22d to prevent unintended rotation of the sleeve 28.

[0050] As can be appreciated, the instrument drive unit 20 described above improves the availability of the surgical robot system 1, reduces the footprint of the entire system 1, improves the safety architecture, reduces the time required to remove surgical instruments in an emergency, and simplifies the electronic equipment used in the instrument drive unit 20.

[0051] It should be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be interpreted as limiting, but merely as an illustration of various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims attached hereto.

Claims

1. An instrument drive unit for use in a robotic surgery system, the instrument drive unit comprising: a carriage configured to be coupled to the robotic arm; a plurality of drive shafts rotatably supported in the carriage; a plurality of electric motors disposed in the plurality of drive shafts, each of the plurality of electric motors comprising a stator and a rotor disposed within the stator; and a plurality of drive gears, each of the plurality of drive gears being fixed to a corresponding drive shaft of the plurality of drive shafts and being configured to interface with a corresponding driven member of the electromechanical surgical instrument, wherein each rotor is configured to rotate a corresponding drive gear of the plurality of drive gears in response to activation of a corresponding electric motor of the plurality of electric motors to actuate a function of the electromechanical surgical instrument, wherein the instrument drive unit further comprises a plurality of gear rings, each of the plurality of gear rings being fixed to a corresponding rotor and operably coupled to a corresponding drive gear of the plurality of drive gears, wherein at least a first gear ring of the plurality of gear rings has gear teeth on an inner periphery thereof, wherein the gear teeth on the inner periphery of the first gear ring interface with a corresponding drive gear of the plurality of drive gears, and an outer periphery of the first gear ring is attached to an inner periphery of a corresponding rotor, wherein each stator is fixed relative to the carriage and each rotor is rotatable relative to and within a corresponding stator, wherein the plurality of electric motors are stacked vertically within the carriage, wherein each of the plurality of gear rings is concentrically disposed within a corresponding rotor such that rotation of the rotor causes rotation of a corresponding gear ring of the plurality of gear rings, The plurality of ring gears are vertically stacked within the plurality of electric motors.

2. The instrument drive unit according to claim 1, further comprising: a sleeve rotationally coupled to the distal end portion of the carriage and configured to non-rotatably retain the electromechanical surgical instrument; and A drive motor comprising: a stator fixed in the carriage; and A rotor is disposed within the stator of the drive motor and non-rotatably coupled to the sleeve, wherein the rotor of the drive motor is configured to rotate the sleeve about a central longitudinal axis defined by the carriage.

3. An instrument drive unit according to claim 1, wherein a first electric motor among the multiple electric motors, a first ring gear among the multiple gear rings, and a first drive gear among the multiple drive gears are operably connected to each other and aligned along a first plane, and wherein a second electric motor among the multiple electric motors, a second ring gear among the multiple gear rings, and a second drive gear among the multiple drive gears are operably connected to each other and aligned along a second plane vertically displaced from the first plane. The instrument drive unit of claim 1 , wherein the plurality of ring gears are independently rotatable relative to one another.

5. The instrument drive unit of claim 1, wherein the plurality of drive gears are vertically offset from one another.

6. The instrument drive unit of claim 1, wherein each of the plurality of drive shafts has a distal end portion configured for interfacing with a corresponding driven member of the electromechanical surgical instrument.

7. An instrument drive unit according to claim 1, wherein each of the multiple drive shafts has a series of idling gears rotatably arranged around it and vertically offset from each other, and the series of idling gears are interfaced with corresponding ring gears to stabilize the multiple drive shafts within the multiple electric motors.

8. An instrument drive unit for use in a robotic surgery system, the instrument drive unit comprising: a carriage configured to be coupled to the robotic arm; a plurality of electric motors supported in the carriage, each of the plurality of electric motors comprising a stator and a rotor disposed within the stator; and a plurality of drive shafts disposed within the plurality of electric motors and configured for interfacing with corresponding driven members of an electromechanical surgical instrument, each of the plurality of drive shafts having a drive gear fixed thereabout, each drive gear disposed at a discrete vertical position relative to one another, wherein each rotor is configured to rotate the corresponding drive gear in response to activation of a corresponding electric motor of the plurality of electric motors to actuate a function of the electromechanical surgical instrument, The instrument drive unit further includes a plurality of vertically stacked ring gears, each of the plurality of ring gears being fixed to a corresponding rotor and operably coupled to a corresponding drive gear, such that each rotor is configured to rotate the corresponding drive gear in response to activation of a corresponding electric motor of the plurality of electric motors to actuate a function of the electromechanical surgical instrument, wherein at least a first gear ring of the plurality of gear rings has gear teeth on an inner periphery thereof, wherein the gear teeth on the inner periphery of the first gear ring interface with a corresponding drive gear, and an outer periphery of the first gear ring is attached to an inner periphery of a corresponding rotor, wherein each stator is fixed relative to the carriage and each rotor is rotatable relative to and within a corresponding stator, wherein the plurality of electric motors are stacked vertically within the carriage, wherein each of the plurality of gear rings is concentrically disposed within a corresponding rotor such that rotation of the rotor causes rotation of a corresponding gear ring of the plurality of gear rings, The plurality of ring gears are vertically stacked within the plurality of electric motors.

9. An instrument drive unit according to claim 8, wherein a first electric motor among the multiple electric motors, a first ring gear among the multiple ring gears, and a first drive gear attached to a first drive shaft among the multiple drive shafts are operably connected to each other and aligned along a first plane, and wherein a second electric motor among the multiple electric motors, a second ring gear among the multiple ring gears, and a second drive gear attached to a second drive shaft among the multiple drive shafts are operably connected to each other and aligned along a second plane vertically displaced from the first plane.

10. The instrument drive unit according to claim 8, further comprising: a sleeve rotationally coupled to the distal end portion of the carriage and configured to non-rotatably retain the electromechanical surgical instrument; and A drive motor comprising: a stator fixed in the carriage; and A rotor is disposed within the stator of the drive motor and non-rotatably coupled to the sleeve, wherein the rotor of the drive motor is configured to rotate the sleeve about a central longitudinal axis defined by the carriage.

11. The instrument drive unit of claim 8, wherein each of the plurality of drive shafts has a distal end portion configured for interfacing with a corresponding driven member of the electromechanical surgical instrument.

12. An instrument drive unit according to claim 8, wherein each of the multiple drive shafts has a series of idler gears rotatably arranged around it and vertically offset from each other, and the series of idler gears are interfaced with corresponding ring gears to stabilize the multiple drive shafts within the multiple electric motors.

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