WO2007114975A2

WO2007114975A2 - Center robotic arm with five-bar spherical linkage for endoscopic camera

Info

Publication number: WO2007114975A2
Application number: PCT/US2007/060948
Authority: WO
Inventors: Bruce Schena
Original assignee: Intuitive Surgical, Inc.
Priority date: 2006-01-25
Filing date: 2007-01-24
Publication date: 2007-10-11
Also published as: JP2014061439A; WO2007120952A2; JP5386178B2; JP2014004682A; JP2012139816A; JP2009524530A; CN101360462A; JP5153650B2; CN101360462B; EP3045274A2; JP5656296B2; KR20080091236A; US20130338434A1; US9907458B2; JP2009524498A; JP5787363B2; CN101856273B; KR20080092346A; KR101304280B1; EP3517256A1

Abstract

A robotic arm (116,100,102) including a parallel spherical five-bar linkage with a remote center of spherical rotation. The robotic arm movably supports an endoscopic camera (104). Two outboard links (702,703) are pivotally coupled together. At least one of the two outboard links supports the endoscopic camera. Two inboard links (701,704) are respectively pivotally coupled to the two outboard links such that the two inboard links are able to cross over one another. The two inboard links moveably support the two outboard links. A ground link is pivotally coupled to the two inboard links. The ground link moveably supports the two inboard links.

Description

CHNTHR ROBOTiC ARM WTI H FiVE-BΛR SPHHRICΛL LINKAGE

FOR ENDOSCOPIC CAMtRA

FlHLD

The embodiments of the invention relate generally to robotic surgical systems More particularly, the embodiments of the i m ention relate to linkage in robotic arms.

BACKGROUND OF TlIT- INVENTION

Minimally invasive surgcrv (VUS) provides suαricai techniques for operating on a patient through small incisions using a camera and elongated surgical, instruments introduced to an internal surgical site, often through trocar sleeves or cannulas I he surgical site often comprises a body cavity, such as the patient's abdomen I he body emit) may optionally be distended using a clear fluid such as an insufflation gas In traditional minimally invasive surgery, the surgeon manipulates the tissues using end etTectors of the elongated surgical instruments by actuating the instrument's handles while viewing the surgical site on a video monitor

A common form of minimally invasive surgery is endoscopy Laparoscope is a type of endoscopy for performing minimal!) invasive inspection and surgery inside the abdominal cavity ϊn standard laparoscopic surgery, a patient's abdomen is insufflated with gas. and cannula slee\ es are passed through small (generally 1/2 inch or less) incisions to provide entry ports for laparoscopic surgical instruments The laparoscopic surgical instruments general!) include a laparoscope (a type of endoscope adapted for viewing the surgical field in the abdominal cavitv) and working tools The working tools are similar to those used in conventional (open) surgery'. except that the working enά or end effector of each tool is separated from its handle by a tool shaft As used herein, tlie term "end effector" mean* the actual working part of the surgical instrument and can include damps, graspers, scissors, staplers, image capture Senses, and needle holders, for example The end effector for the laparoscope may include lenses and light sources that may be optically couple to a camesa and lamps through the tool shaft To perform surgical procedures, the surgeon passes these working tools or instruments through the cannula sleeves to an internal surgical site and manipulates them from outside the abdomen The surgeon monϊtots the procedure by means of a monitor that displays an image of the surgical site taken from the laparoscope Similaj endoscopic techniques aie employed in othei types of surgeries such as arthroscopy, retroperitoneoscopy, pehϊseopy, nephroscopy, cystoscopy , cisternoscopy, sinoscopy, hysteroseopy, urethroscopy, and the like BRIEF_.SUMMARY The embodiments of the invention are summarized by the claims that follow belo^v.

BMi£πESCRjPπθM.QFJΗ£ DMMNGS

FlG. i is a plan view of a surgical suite in which embodiments of the invention are used. FIG. 2 is a plan view of a portion of the operating suite of FlG, 1.

FIG. 3 is a side view of a portion of the operating suite of FlG. 2,

FIG 4 is a schematic view of a parallel five-bar linkage.

FIG 5 is a schematic view of a parallel spherical five-bar linkage.

FIG 6 is a schematic view of another parallel spherical five-bar linkage. FIG. 7 is a pictorial view of an embodiment of the invention.

FIG 8 is a view of a first side of an embodiment of the invention,

FKJ ^C> is a bottom view of the embodiment of the invention shown in FlG, 8

FIG. 10 is view of a second side of the embodiment of the invention shown in FIG S.

FIG. 1 1 is a top view of the embodiment of the invention shown in FIG. 8, FIG. 12 is an end view of the embodiment of the invention shown in FIG. 8.

FIG i 3 is a pictorial view of a portion of the embodiment as shown in FICr. 12

FlG 14 is a bottom view of the embodiment of the invention as shown in FlG V in a different operative position.

FIG i 5 is a bottom view of another embodiment of the invention, FlG 16 is an end view of another embodiment of the invention.

FIG 1.7 is a schematic view of a parallel spherical five-bar linkage.

FIG. I S is a schematic slew of another parallel spherical five-bar linkage.

FIG. UHs a pictorial view of another embodiment of the invention.

FIG. 20 is a schematic view of the parallel spherical five-bar linkage shown in FlG 19 FlG. 21 is a pictorial view of another embodiment of the invention.

E>OΑ!L.OIIMSCRjPI}ONi⁾^

The detailed description describes the invention as it may be used in a laparoscopic, surgery. H is to be understood that this is merely one example of tlie types of surgeries in which the invention may be used. The invention is not limited to laparoscopy nor to the particular structural configurations shown which are merely examples to aid in the understanding of the invention. Traditional minimally invasive surgery requires a high degree of surgical skill because the surgeon's hand movements are controlling a surgical tool at a substantial distance from the surgeon's hands, often requiring unnatural and non-intuitive hand motions. In robotically assisted surgery, a surgeon may operate a master controller to control the morion of surgical instruments at the surgical site. Servo mechanisms may move and articulate the surgical instrument based on the surgeon's manipulation of the hand input devices. The robotic assistance may aliow the surgeon to control the motion of surgical instalments more easily and with greater precision

Figure 1 shows a schematic plan view of a surgical suite in which the invention may be used. A patient 1 10 is shown on an operating table 1 12 undergoing robotically assisted laparoscopic surgery, A surgeon 120 may use a master controller 122 to view a video image of the internal surgical site provided by an endoscopic camera, a laparoscopic camera 104 in the case of abdominal surgery, and control one or more surgical instalments and the endoscopic camera by means of robotic servo mechanisms. The master controller 122 will typically include one or more hand input devices (such as joysticks, exoskeletal gloves, or the like) which are coupled by a servo mechanism to a surgical instrument.

A robotic arm 1 16 that embodies the invention may be used to support and move the laparoscopic camera 104 at the surgical site during robotically assisted surgery. It is desirable to support the laparoscopic camera 104 such that the tool shaft 1 18 of the instalment and the cannula 106 through which it passes pivot about a center of spherical rotation positioned in space along the length of the tool shaft and cannula. Additional robotic arms 100, 102 may support and move surgical instruments. The robotic amis 100, 102 for supporting the surgical instruments may be of a different form than the robotic arm 1 16 for supporting the laparoscopic camera.

Each robotic arm 100, 102, 1 16 may be supported by an articulated set-up arm 130, 132, 134. The set-up arms may be attached to the operating table 1 12. Each set-up arm may include a number of segments coupled by joints that provide one or more degrees of freedom that allow the robotic arm to be positioned within a defined range of motion. One or more locking mechanisms may he provided to fix the segments and joints of the set-up arm when the robotic ami is in the desired position. The set-up arms may allow the robotic arms 100, 102, 1 16 to be fixed at an arbitrary position with respect to the operating table and the patient thereon. Joint angle sensors may be provided on the set-up arm to allow the pose of the set-up arm and the resulting position of the supported robotic arm to be determined.

Each robotic arm 100, 102, i 16 may be fixed at a position where the center of spherical rotation is substantially at the access point to the internal surgical site (for example, with the incision that provides entry for the trocar or cannula 106 at the abdominal wall during laparoscopic surgery) Λn end effector of the surgical instrument 104 supported by the robotic arm 1 ) b can be positioned safely by inox iog the proximal end of the too! shaft 1 18 vuth the robotic ami 1 ! 6 without imposing dangerous forces against the abdominal wall Fach iobotic aim K)O₁ 102, 1 16 will support one surgical instrument which max be detachable from the robotic arm While a variety of surgical instruments 108 may replace the surgical instrument on the robotic arm 100, 102 during the course of a single surgery the laparoscopic camera 104 is generally left in place throughout the course of a surgery Each robotic arm 1 1 (> may support a cannula 1Oo that passes through an incision into the bodx of the patient 1 10 The tool shaft 1 18 of the surgical instrument or laparoscopic camera 104 passes through the cannula 106 to the internal surøical site

The robotic arm 1 16 may support the laparoscopic camera 104 such that the cannula 105 and the too! shaft 1 ! 8 of the instrument pivot about a center of spherical rotation positioned in space along the length of the cannula 106 The center of spherical rotation may also be called the remote center of spherical rotation because it is the spherical center of rotational motion for the robotic arm while being spaced apart from the structure of the robotic arm Motion about the center of spherical rotation max be described as spherical motion because a point at a radial distance from the center of spherical rotation wili move on a spherical surface hav ing the radial distance as its radius The cannula 106 defines an insertion axis that passes through art access point, such as an incision in the abdominal wall of the patient 1 1 C), to the internal surgical site The tool shaft 1 18 extends along the insertion axis

Fach robotic arm 100, 102, 1 16 may include one or more servo motors to moλ e the arm to a desired position Fach robotic arm may include one or more additional servo motors to move the surgical instrument oi laparoscopic camera 104 and'Or an end effector on the surgical instrument or laparoscopic camera One ot more control cables 124 may provide signals between the computer 123 in the mastei controller 122 and the servo motors of the robotic arms 100, 102. 1 16 The master controller 122 rnav include a computer S 23 to provide signals that control the servo mechanisms of the robotic arms, the surgical instruments, and laparoscopic camera based on the surgeon's input and received feedback from the servo mechanisms Figure 2 shows an enlarged view of a portion of Hgure 1 including the patient 1 10 and the robotic arms 100, 102, 1 16 Figure 3 shows an side view of the robotic arm 1 16 that supports and mov es the laparoscopic camera looking from the patient's left hand side Λ schematic cross-section of the patient U O is shown in {he area where the cannula 1 Oh is inserted through an incision 3 14 in the abdominal xvall The tool shaft 1 18 of the laparoscopic camera 104 may be seen emerging from the end of the cannula 106 interna! to the patient ] J O Λn end effector 300 at the distal end of the tool shaft 1 J 8 may provide lenses and light sources The Senses and light sources may be optically coupled to a camera and lamps through the tool shaft The camera and lamps may be supported by the iobotic aim 1 i b at a proximal end of the tool shaft

The robotic arm i 16 includes a spherical linkage to support the laparoscopic camera, as Λvtϋ be discussed in greater detail below The spherical linkage constrains the motion of the insertion axis to rotation about a remote center of spherical rotation 3Od which ma\ be located along the length of the cannula 1 Ob By locating the remote center of spherical rotation 306 at or near the incision 3 14, the insertion axis may be moved without significant lateral motion at the incision

The end effector 300 is passed through the cannula 106 to the internal surgical site along the insertion axis The end effector ^ 00 is supported by the tool shaft 1 18 and coupled to one or more of cameras, lamps, and ser\ o mechanisms through the tool shaft Translation of the end effector 300 may be accomplished by translation of the laparoscopic camera 104 with the tool shaft ϊ 18 and attached end effector

The end effector 300 may be

ed in two additional dimensions by moving the tool shaft 1 18 about its remote center of spherical rotation 306 The robotic arm 1 16 will control these two dimensions of motion by moving the tool shaft 118 to change its angular position in space The motion of the tool shaft 1 I S may be described in term;*, of the position of the insertion axis m a spherical coordinate system A point in space may be specified in terms of two angles and a distance from a center of a spherical coordinate system It will be appreciated that only the two angles are necessary to specify an insertion axis that passes through the center of the spherical coordinate system The robotic arm 1 16 of the present invention includes a parallel spherical five-bar linkage to e and support the laparoscopic camera 104 such that the tool shaft 1 18 of the instrument pivots about a remote center of spherical rotation 306 positioned in space along the insertion axis and generally along the length of the cannula 106

Figure 4 A shows a simplified, 2-dimensionaS schematic diagram of a parallel five-bar linkage 400 This example illustrates the linkage operating in essentially a flat plane I he im entive linkage opesates similarly in 3~<limeπsional space and will be described sub_.equentl> A parallel five-bar linkage is a system of four rigid bars or links 401 , 402, 403, 404 pivoted to each other and to a fixed base link 405 The fixed base link may be referred to as the ground link It is to be understood that the ground link 405 is fixed onlv in the sense that it provides a fixed frame of reference for the remaining four links I he ground Sink 405 may be positioned in space to move the entire five-bar linkage 400

Rach link includes tw o pivot axes In the present invention, there is a substantial distance een the two pivot axes on each Hnk All of the pi v ot axes 4 W , 4 i 2, 413, 414, 415 as e perpendicular to a common sυs face The links are coupled at the pivot axes such that the links can rotate relative to each other about the pivot axi^ at which the\ are coupled The rotatable coupling of the links at a

ot axis can take any of a variety of forms that limits the motion of the coupled links to rotation about the pivot aλis A number of axes are described for the parallel spherical five-bar linkage The term "axis" roa\ be used interchangeablj to refer to a "joint" or a "pivot" except for the insertion axis

The ground link 405 provides two inboaid axes 412, 413 An inboaid link 401 , 404 is pivotaliv coupled to each of the inboard axes 413, 412 fcach inboard link 401, 404 has an intermediate axis 414, 41 1 spaced apart from the inboard axis 413, 412 Each inboard link 401 , 404 is pivotaliv coupled to an outboard link 402, 403 at the intermediate axis 414. 41 1 Each outboard Hnk 402 403 has an outboard axis 415 spaced apart from the intermediate axis 414 41 3 ^'S he two outboard links 402, 403 are pivotaliv coupled together at the outboard axis 41 5 The outboard axis 41 > can be positioned perpendicular to {he common surface (in this 2- dimensional illustrative example) anywhere within its range of motion thus providing an endpoint motion at the outboard axis 41 5 with two degrees of freedom If motors are provided to rotate each of the inboard links 401 , 404 about their inboard axis 413, 412, as suggested by the arrows, the outboard axis 41 5 may be positioned anywhere within its range of motion by rotating the two inboard links with the motors Conversely, movement of the outboard axis 415 within its range of motion translates into rotation of the two inboard links 40 i , -UM about their inboard axis 413, 412 Λ linkage that couples rotation of two grøund-f eferenced independent iiπkt> with two dimensional movement of an axis is a parallel linkage The rotarv motion provided by the two motors to the two inboard links may be described as parallel rotary motion inputs It should be noted that ^"parallel " is used here to indicate two inputs that are provided independent!) of one another and not in the geometric seme to indicate the direction of the inputs In a parallel linkage, the two independent parallel inputs act upon the same body at some distal point where links coupled to the inputs, join to drive the same object or link tt w ill be appreciated that there arc two post>iblc positions, for each of the inboard links 401. 404 in a five-bar linkage for most of the possible positions of the outboard axis For example, the inboard links 401, 404 could also be positioned as indicated bv the dallied lines 40 V, 404'. These positions for the inboard links are generally considered undesirable because the distance between the intermediate axes 414', 411' is reduced and the angle between the outboard links 402\ 403' is reduced. Ii is normally desirable to maximize the distance between the intermediate axes to provide a broad base of support for the outboard axis 415. It is aϊso normally desirable to have the outboard links 402', 403' as close to being at right angles to one another as possible to support the outboard axis 415. While the conventional configuration of a five-bar linkage provides good structural support for the outboard axis 415, the resulting structure requires a substantial amount of space in which to move. The alternative configuration as indicated by the links 401 \ 402\ 403', 404^: drawn with dashed lines occupies a smaller area (as projected onto the plane) and is therefore a more compact mechanical configuration.

Figure 48 shows the parallel five-bar linkage 400 after the inboard links 401 , 404 have been rotated in a counter-clockwise direction, ϊt may be seen that the outboard axis 415 has been moved generally to the left by the rotation of the inboard links 401 , 404. The same position of the outboard axis 415 may also be produced by a similar rotation of the inboard links 40! ', 404^! when the parallel five-bar linkage 400 is in the compact mechanical configuration illustrated by the dashed lines.

A spherical linkage for the purposes of this description is a 3 -dimensional version of the 2 -dimensional mechanical linkage described above. In the 3-dimerisional linkage, all pivot axes pass through a common remote center of spherical rotation. "Pass through" includes axes that may be slightly displaced (due to slight errors in manufacturing of the physical links, for example) from the remote center of spherical rotation to accommodate the structural limitations of the robotic mm where the displacement is small enough that the linkage has substantially the same kinematics (characteristic motions) as if the axes actually included the precise, theoretical remote center of spherical rotation. Note that axes that pass through a remote center of spherical rotation are also perpendicular to a spherical surface centered on the remote center of spherical rotation.

Figure 5 shows a schematic diagram of a parallel spherical five-bar linkage 500. As with the previously discussed planar five-bar linkage, the parallel spherical five-bar linkage 500 is a system of four rigid links 501 , 502, 503, 504 pivoted to each other and to a fixed base or ground link 505. When a parallel five-bar linkage is constructed in a spherical form, all of the pivot a,χes 51 1 , 512, 513, 514, 515 are perpendicul ar to a common spheri cal surface and therefore pass through a remote center of spherical rotation 520 of the common spherical surface. In particular, the outboard axis 515 will always pass through the remote center of spherical rotation

520 within its range of motion. Thus, a parallel spherical five-bar linkage 500 provides the desired constrained motion for a surgical instrument such that the tool shaft of the instrument pi\ (its about a remote center of spherical rotation Λvhen supported, and moved by the outboard axis 515 of the linkage 500 The motors to move the surgical instrument are placed at the inboatd axes 513, 512 of the ground link 505 T his, avoids the need to move one motor with the othei motor as might be required if a serial arm mechanism were used

Λs shown schematically in Figure 6Λ, it lias been discovered that a parallel spherical fi\ c-bar linkage 600 can be constrained so that the intermediate axes 614, 6i i do not assume the conventional configuration where the intermediate axes are at their maximum possible separation and, surprisingly, provide good structural support for the outboard axis 615 This results in a more compact configuration that is better suited for use as a robotic arm to support an endoscopic camera where it is often necessar) to have other robotic arms in close proximity within a limited amount of space as shown by the exemplary system in Figures 1 and 2

The pat al IcI spherical fi\ c-bar linkage 6θύ shown schematically includes a ground link 005, two inboard links 601, 604 pivotally coupled to the ground Sink, and two outboard Sinks 602 603 pivotally coupled to each other at one end and to the two inboard links 60 ! ,604 respectively at an opposite end The first inboard link 601 is pivotally coupled to the ground link 605 at a first axis of rotation 6 i 3 The first inboard link 601 further includes a first intermediate axis 614 at a first distance from the first avis of rotation 613 Λ first outboard link 602 is pivotally coupled to the first inboard link bOl at the first intermediate axis 614 The first outboard link 602 has an outboard axis 615 at a second distance from the first intermediate axis 614

T he second inboard link 604 is pivotaliy coupled to the ground link at a second axis of rotation 612 The second inboard link 601 has a second axis of rotation 612 that is separated from the first axis of rotation 013 by a fourth distance The second inboard link 604 further includes a second intct mediate axis 61 1 at a fifth distance from the second axis of rotation 612 A second outboard link 603 is pivoiallv coupled to the second inboard link 604 at the second intermediate axis 61 1 and to the first outboard link 602 at the outboard axis 615 The outboard axis 615 is at a sixth distance from the second intermediate axis 61 1

A mechanical stop may limit the rotation of the outboard links 602, t>03 about the outboard axis 615 such that a minimum angle is maintained between the outboard links, perhaps a minimum angle in the sange of 15 to 30 degrees I he links are assembled and constrained such that when the outboard axis 615 lies in a plane 622 that is the perpendicular bisector of the line segment from the first axis of rotation 613 to the second axis of rotation 612. each of the inboard links 601, 604 intersects 624 the bisecting plane 622 (The double dashed lines_* arc intended to suggest an edge of the portion of the imaginary bisecting plane 622 in the vicinity of the linkage 600. The dashed circle indicates the point of intersection between each of the inboard links 601, 604 and the bisecting plane 622, which is at the same place for the configuration and pose shown.) When an inboard link intersects the bisecting plane, the axis of rotation and the intermediate axis will lie on opposite sides of the plane, ft will be appreciated that this requires the inboard links 601, 604 to be able to cross over one another.

A specific position assumed by a robotic arm may be referred to as a pose. Placing a robotic arm in a specific position may be referred to as posing the robotic arm. The parallel spherical five-bar linkage may be limited in its motion such that the two intermediate axes 614, 61 1 are relatively close together compared to the maximum separation possible for any given pose of the robotic arm 600. In particular, each inboard link 601. 604 may be in one of two positions for a given position of the outboard axis 615, except for the singularities where the axis of rotation 6S2_T 613, the intermediate axis 61 1 , 614, and the outboard axis 615 are coplanar. One of the two positions for each of the two inboard Sinks 601, 604 will provide the maximum distance between the intermediate axes 61 1, 614. The pose where each of the two inboard links 601, 604 is in the other of the two positions will be described as the compact pose. It will be appreciated that this always results in less than the maximum distance between the intermediate axes 61 1, 614 although it may not result in the minimum possible distance. If the outboard links are constrained to maintain at least a minimum angle between the outboard links and the parallel five-bar spherical linkage is assembled in a compact pose, then the linkage will be limited to a range of compact poses.

Figure 6B shows the parallel spherical five-bar linkage 600 after one of the inboard links 601 has been rotated in a counter-clockwise direction. It may be seen that the outboard axis 615 has been moved generally to the left by the rotation of the inboard Sink 601 It may also been seen that points on the outboard axis 6! 5 are constrained to move on a spherical surface. In the pose shown in Figure 6B neither of the two inboard links 601 , 604 intersect the bisecting plane 622, It will be observed that the linkage 600 retains the compact configuration even though it has moved away from the pose where the outboard axis 615 lies in a plane 622 that is the perpendicular bisector of the line segment from the first axis of rotation 613 to the second axis of rotation 612.

Referring now to Figure 7 A, the inboard links 701, 704 and the outboard links 702, 703 are illustrated for the embodiment shown in Figures 1 -3 T he ground link, which is provided by a motor assembly, is not shown in Figure 7 to allow the relationship between the four moving links to be better seen. The two inboard links 70! , 704 each can rotate about one of the axes of rotation 713, 712 Each inboard link 701. 704 is pivotaily coupled to an outboard link 702, 703 at an intermediate axis 7 U , 714 The two outboard links 702, 703 are pi\ otaily coupled together at an outboard axis 715 The outboaid axis ? 15 may also be the insertion axis on which the cannula (not shown) is centered In some embodiments, the first axis 713 and second axis 712 of rotation aie driv en bj motors connected to a controller that provides signals to the motors A first motor may rotate the first inboard link 701 and a second motor may rotate the second inboard link 704 The control ler may limit the motion of the links so that the parallel five-bar spherical linkage is limited to a range of compact poses The controller may limit the motion of the inboard links 70U 704 such that each of the inboard links 701, 704 intersects a perpendicular bisecting plane of the lino segment fϊom the first axis of rotation 713 to the second axis of rotation 712 when the outboard axis 715 lies in the bisecting plane When an inboard link intersects the bisecting plane, the axis of rotation and the intermediate axis will lie on opposite sides of the bisecting plane The controller may also limit the rotation of the inboard Sinks 70 S , 704 such that a minimum angular distance is maintained between the intermediate axes 7 ! i, 714, perhaps a minimum angular distance in the range of 15 to 30 degrees The controller can provide the same constraint on the range of motion of the links 701 -704 as a mechanical stop that limits the angle between the outboard Sinks 702, 703 at tiie outboard axis 715

The parallel spherical five bar linkage may be used to move the outboard axis 71 5 to a desired position by controllable rotating the inboard links 70L 704. such as b\ use of a servo motor or stepper motor Figure 7B illustrates the parallel spherical five bar linkage after one of the inboard links 701 has been rotated in a counter-clockw ise direction The poses of the parallel spherical five bar linkage shown in Figures 7 A and 7B are general!) similar to the poses of the parallel spSierieai five bar linkage shown schematically in Figures 6A and 5B respectively In another embodiment, the parallel spherical five bai linkage may be used to sense a position of the outboard axis by determining tSie bearings of the two inboard axes that result from manipulation of the outboard axis For example, rotary encoders, or other sensors, may be placed at the first 713 and second 712 axis of rotation of the parallel spherical Five bar linkage illustrated by Figure 7 The controller may be repSaced by a computer coupled to the two rotary encoders to receive the bearing of eacSi of the inboard links 701 , 704 I he computer may then compute the position of the outboard axis, which may be manipulated

an operator to provide a position input It will be appreciated that the outboard axis is constrained to rotate about the remote center of spherical rotation ⁷20 of the spherical linkage Thus, the parallel spherical five bat linkage may also be used in the control console 122 of Figure S to rcceix c position input for the outboard axis 715 from the surgeon 120 I he position input will have the same constrained motion as the outboard axis of the robotic arm U 6

Referring now to Figures 8, 9, 10, 1 1 , and 12, orthogonal views are shown for fout .sides and an end of the robotic arm i 16 used to support the laparoscopic camera in the same pose as shown in Hguies 1 -3 Figure § is a first side view higure 9 is a bottom view Figure 10 is a second side view of the side opposite the first side Figure 11 is a top view Figure 12 is a view of the end that is to the right in Figures 8-1 1

I- igures S- 12 show a robotic arm 1 16 that embodies the in\ enti on The robotic arm includes a motor assembh 800 that sen es as a ground link and four movable links 701 , 702 703, 704 to provide a parallel spherical five bar linkage The relationship of the four movable links was discussed above in connection with Figute 7 The motor assembly 800 provides two rotatable shafts 802, 804 Each of the rotatable shafts is coupled to one of the two inboard Sinks 701, ⁷04 at one of the axes of rotation 713, 712 (bbown in Figure 7) A cannula i 06 is supported by the two outboard links 702, 703 in a position that is coaxial with the outboard axis 7 ! 5 (shown in Figure 7) In this embodiment, the outboard axis 71 5 is coincident w ith the insertion axis for the tool shaft of an endoscopic camera

Figure 13 shows the robotic aim \ 16 of Figure 12 with the two outboard links 702. 703 removed so that the relationship betw een the motor assembly 800 and the tuo inboard links 701 , ⁷04 can be seen The motor assembly 800 and the two inboard links 701 , 704 are shaped and coupled in a configuration that allow s the two inboard links to pass over one another and the motor assembly It may be seen that the two rotatable shafts 802. 804 emerge from the motor assembly 8(K) in substantially opposite directions m this embodiment The two rotafable shafts 802, SOl may be driven by motors coupled to the shafts through right angle drix es, such as a worm and helix dri\ e One inboard link 701 moves within a spherical "shell" that is closer to the center of spherical motion than the motor assembly The other inboaid link 704 moves within a spherical "shell" that is further from the center of spherical motion than the motor assembly The motor assembly 800 lies between these tuo spherical "shells " Thus one pair of links passes the motor assembly to the inside and the other pair of links passes to the outside Figure 14 shows the f obotic as m 1 1 ό° of Figure 9 in a pose with the outboard axis 806 close to the motor assembly 800 (The motor assembly 800 is drawn as though transparent as suggested by the dashed lines to alitw, the configuration of the movable links 70 P, 702', 703', 704' to be seen ) One inboard link 701 ', w hich is coupled to a first rotatabie shaft 802 that extends toward the remote spherical centci, and the coupled outboard link 702' have passed to the inside of the motor assembly 800 These links Ue between the motor assembly 800 and the remote spherical center The other inboard link 704', which is coupled to a second rotatable shaft 804 that extends away from the remote spherical center, and the coupled outboaid link ?03^l have passed to the outside of the motor assenibh &00 Ihe motor assembly SOU lies between these links and the remote spherical center

Figure 1 5 shows another robotic arm 1500 that embodies the invention The motor assembly includes two motors 1502, 1504 that are coupled by a support 1506 at a substantial distance from the two axes of rotation ! 508, 1510 The motor assembly provides the ground link for the parallel spherical fn e bar linkage This configuration of the support 1505 ma) permit the outboard axis 1512. which may also be the axis for the cannula 1514, to pass between the two axes of iotation 1 *>08, 1510 and the two motors 1502, 1 ^04 to provide a greater range of motion Figure 16 shows still another robotic arm IbOQ that embodies the invention The motor assembly includes two mofots 1602, 1504 that are coupled by a support 1606 to provide the ground Sink for the parallel spherical fh e bar linkage The two axes of rotation 1608, 1610 πia\ coincide with axes of the two motors 1602, 1604 such that a right angle drive is not required At least one of the inboard Sinks 1614 has an angular length that is substantially less than the angular distance between the two axes of rotation 160S, !610 This permits the inboard link 1614 to the motor 1604 that is coupled to the other inboard link 1616 The other inboard link Id 16 may or may not have an angular length that is substantially less than the angular distance between the two axes of rotation 1608, 1610 as it may be configured to pass to the inside of the motor 1602, between the motor and the remote spherical center, that is coupled to the shortened inboard link 1614

Figure 17 shows a schematic representation of a robotic arm 1700 that is similar to the robotic arm 1600 shown in Hguse 16 A first pair of Inboard and outboard links 1701. 1702 are ptvotallv coupled at a first intermediate axis 1714 A second pair of inboard and outboard links 1704, 1703 are pivotal Iv coupled at a second intermediate axis 17 ! 1 The two outboard links 1702, 1703 are pivotal Iv coupled at an outboard axis 1715 One of two motors 1733, 1734 is coupled to each of the inboard links 1 701, 1704 to rotate the inboard link about an axis of rotation 1 713. 17 ! 2 The two motors are coupled by a ground S ink 1705 to complete the parallel spherical five-bar linkage

It may be observed that the first pair of inboard and outboard links i 70 K 1702 ma> be constructed so that they move Vvithin a first spherical shell 1736 The second pair of tnboatd and outboard links 1 704, 1703 move within a second spherical shell 1738 that is not shared with the lit st spherical shell 1736 except in the vicinity of the outboard avis 1715 This arrangement permits the inboard links 1701, 1704 to cross over one another. The inboard links 1701, 1704 in this arrangement may also pass to the inside, closer to the remote center of spherical rotation 1720, of the ground link 1 705 that couples the two motors 1733, 1734 if the ground link lies outside the second spherical shell 1738. The arrangement of the linkage 1 700 has the further characteristic that when the first inboard link 1701 lies in the same plane as the ground link 1705 as shown, a first directional vector 1 721 from the first axis of rotation 1 713 to the first intermediate axis 1714 has the same direction as a second directional vector 1722 from the first axis of rotation 1713 to the second axis of rotation 1712. Likewise, when the second inboard link 1 704 lies in the same plane as the ground Sink 1705, a third directional vector 1723 from the second axis of rotation 1712 to the second intermediate axis 171 1 has the same direction as a fourth directional vector 1724 from the second axis of røtati on 1712 to the first axis of rotation 1713.

Figure 18 shows a schematic representation of a robotic ami 1800 that is similar to the robotic arm i 16 as shown in Figure 1 S . A first pair of inboard and outboard links 180L 1802 are pivotally coupled at a first intermediate axis 1814. A second pair of inboard and outboard links IS04_; 1803 are pivotally coupled at a second intermediate axis 181 1. The two outboard links 1802, 1803 are pivotally coupled at an outboard axis 1815. One of two motors 1833, 1834 is coupled to each of the inboard links 1801. 1804 to rotate the inboard Sink about an axis of rotation 1813, 1812. The two motors are coupled by a ground link 1805 to complete the parallel spherical five-bar linkage.

In the arrangement shown in Figure 18, the ground link 1805 is between the two inboard links 1801, 1804 when all three Sinks are in the same plane. The first pair of inboard and outboard links 1801 , 1802 may move within a first, spherical shell 1836. The second pair of inboard and outboard links 1804, 1803 may move within a second spherical shell 1838 that, is not shared with the first spherical shell 1836 except in the vicinity of the outboard axis 1815. If the ground link is within a third spherical shell 1837 that lies between the first and second spherical shells, then the inboard links ISO l, 1804 may cross over one another and also cross over the ground link. The arrangement of the linkage 1800 has the same directionality characteristic when the inboard links 1801, 1804 lie in the same plane as the ground link 1805 as discussed above for the linkage 1.700 shown in Figure 17.

In the arrangement shown in Figure 18, the axes of the motors 1833, 1834 may be perpendicular to the axes of rotation 1813, 1812. This may be done to allow ail or part of the motors to be within the third spherical shell 1837 over which the inboard links 1801, 1804 may pass. A drive shaft 1840, 1842 may couple the motors 1833, 1834 to inboard links 1801 , S 804 by means of a right angle drive 1844, 1846. hi other embodiments, the drive shaft may be coupled to the motors in other arrangements or be a coaxial extension of the motor shaft. The end of the drive shaft 1840, 1842 coupled to the motors 1833, 1834 may be described as the driven end. In. the arrangement shown, it may be observed that a first drive shaft 1 S40 extends from the driven end toward the remote center of spherical rotation 1820 and a second drive shaft 1842 extends from the driven end away from the remote center of spherical rotation 1820.

Figure 19 shows a parallel spherical five-bar linkage 1900 that embodies the invention with a structure similar to the robotic arm 116 shown in Figures 7- 12. Figure 20 shows a schematic view of the parallel spherical five-bar linkage 1900 of Figure 19. Five pivot axes 191 1-1915, about which the four movable links 1901 -1904 rotate, all pass through a common remote center of spherical rotation 1920. The first inboard link 1901 and the second inboard link 1904 may be coupled to motors that caii rotate- the inboard links about the first 1913 and second 1912 axes of rotation. The two motors may be coupled together to form the fifth link (not shown), which is the ground link. The movable links .1901 , 1902, 1903, 1904 are shown as having a generally arcuate form. It will be appreciated that the links may have any desired form without affecting the function of the invention The linkage will function as a spherical linkage as long as the axes of the pivoted connections 1921, 1922, 1923, 1924, 1925 all pass substantially through a common remote center of spherical rotation 1920. Any of the links may have an irregular shape, which may include arcuate segments, to accommodate placement of the pivoted connections such that the links and pivots can pass one another. It will be appreciated that the form of the links is unimportant as long as they support the pivot axes such that they pass substantially through the remote center of spherical rotation 1920.

In the compact configuration of the inventive parallel spherical Five bar linkage, it may be desirable to configure the linkage such that the first pair of links 1901 , 1902 coupling the first axis of rotation 1913 to the outboard axis 1915 can freely pass the second pair of links 1904, 1903 coupling the second asi s of rotati on 1912 to the outboard axi s 1915. Since the only requirement of the parallel spherical five-bar linkage is that all the pivot axes pass substantially through the common remote center of spherical rotation 1920, the first pair of Sinks 1901 , 1902 and the first intermediate pivot 1914 may be configured so that a first volume swept out by the first pair does not intersect a second volume swept out. by the second pair of ϊ inks 1904, 1903 and the second intermediate pivot 191 1. The only connections between the first and second volumes are in the vicinity of the outboard axis 1915 and the ground link 1905. The farm of the links in the embodiment illustrated by Figures 19 and 20 are an example of a configuration that permits the first pair of links J 901, 1902 to pass the second pair of links 1904, 1903.

Figure 21 shows another embodiment of a parallel spherical fsve-bar linkage 2100 for a robotic arm including two inboard links 2101, 2104, two outboard links, and a ground link provided by the motor assembly 2105. In comparison with the linkage 1900 of Figure 19, the parallel spherical five-bar linkage 2)00 includes an outboard Sink 2103 having an insertion axis

21 19 that is spaced apart from the outboard axis 21 15 by an offset distance. Ideally the insertion axis 21 19 is coincident with the outboard axis 21.15. Mechanical packaging advantages can be obtained, however, by separating the insertion axis 21 19 from the outboard axis 2115. Preferably the insertion axis 21 )9 will be placed on the outboard link 2103 further from the intermediate axis 21 1 1 than the outboard axis 21 15. As long as the insertion axis 21 19 is perpendicular to the surface of the sphere centered on the remote center of spherical rotation

2120 and therefore passes through the remote center of spherical rotation 2120, then the insertion axis will have the same kinematic characteristics as the pivot axes 21 11-2 1 1 5 of the parallel spherical five-bar linkage 2100. That is, the insertion axis 2119 will move relative to the remote center of spherical rotation 2120. The insertion axis 2119 may or may not lie in the plane defined by the intermediate axis 2114 and the outboard axis 21 15.

The placement of the insertion axis 21 19 outboard from the pivot axes of the parallel spherical five-bar linkage may allow the endoscopic camera (not shown) to be supported and manipulated without interfering with the motion of the linkage 21 C)O. ϊt may also simplify the construction, installation, removal, and sterile boundary construction of the cannula 2106 and its associated mechanical attachment means.

In some embodiments having a spaced apart insertion axis, such as the one illustrated in Figure 21 , the insertion a.xis 2119, the outboard axis 21 15, and the intermediate axis 21 1 1 may be copianar. This arrangement may simplify the relationship between the positions of the two inboard links 2101 , 2104 and the position of the outboard axis 2115. Note that the insertion axis 21 19 can be placed on either of the two outboard links 2102, 2103 ,

The parallel spherical five-bar linkage of the invention may be described using spherical geometry, which is a plane geometry on the surface of a sphere. While the links of the inventive linkage need not lie of the same spherical surface, or any spherical surface, they can be projected onto a common spherical surface for the purpose of describing the linkage. In spherical geometry, distances may be measured as angles because the geometric relationships on the spherical surface are unaffected by changing the radius of the sphere. Angular distance remains the same regardless of the radius of the sphere. Navigation on the surface of the Earth is a common example of spherical geometry Latitude and longitude as used in global navigation are a familiar system for describing locations and directions in a spherical system The equator defines the points at 0° latitude The north pole defines 90" latitude wύ the south pole defines -W ' latitude Longitude is the angular distance on a circle of constant latitude from an arbitrarily defined line of 0° longitude

Longitude is conventionally expressed as being in the range 180° west to 180° east of the 0° longitude line Bearings are lines of direction from a point expressed as the angle between the bearing and a line of direction to the north pole Westerly bearings can be expressed as positive angles and easterly bearings can be expressed as negative angles The following is a description of an embodiment of the invention expressed in terms of a spherical geometry

Referring again to Figure 6. the first axis of rotation 61 > of the First Inboaid link 601 will be considered as being at 0° latitude and 0^u longitude The second axis of rotation 612 of the second inboaid link 604 is shown as being at the same latitude and at a positive (easterly } longitude The second axis of rotation 612 may be at a fixed position of 55^~ longitude and O" latitude, for example Thus, in this example the ground link has an angular length of S5° It should be remembered thai, a fixed position means fixed within the frame of ieference of the spherical geometry of the linkage and that the entire linkage with its ft arnc of reference may be freely positioned in space

AU of the movable links 60 [ -604 may have the same angular length as the ground link For example, the first intermediate axis 614 may be spaced apatt from the first axis of rotation ό 13 by 55° The first outboard axis 515 may be spaced apart from the first intermediate axis 6 14 by 55° The insertion axis 61 V may be spaced apart from the outboard axis 615 by MY' The second intermediate axis 6 ! I may be spaced apart from the second axis of rotation 6 ! 2 b> *>5° The second intermediate axis 61 1 may be spaced apart from the outboard axis 615 by 55° The range of rotation of the Inboard links 601 , 604 about the axes of iotation 6Lt, 612 may constrained such that a minimum angle of 15° Is maintained between the outboard links 602, 603. for example The range of rotation of the inboard links 601. 1>04 may further constrained such that when the outboard axis 615 has a longitude of 27 5°, for example, the first inboard link 601 has a negative (easterly ) bearing and the second inboard link 604 has a positive (westerly ) bearing The line segment that most directly connects the axis of rotation 613, (> 12 to the intermediate axis 614. 61 1 on the common spherical surface w ill cross the longitude line of the outboard axis 615 for both of the inboard links Thus, the inboard links will cross one another when the outboard axis is at or near the center of its east-west range of motion The constraints on the rotation of the inboard links prevents them from uncrossing when the outboard axis is in the central portion of its east-west range of motion

These dimension are merely by way of example. The insention may be practiced with linkages having substantially different dimensions and substantially different ranges of motion The invention is only limited by the claims, 1{ may be desirable to use different dimensions and different ranges of moti on to adapt the invention for needs of particular types of surgeries which have particular requirements for the range of motion of the insertion axis and for the space occupied by the device through its range of motion

It is to be understood that the inventive parallel spherical Five-bar linkage may be embodied in both powered and unpowered configurations in powered embodiments, devices such as servo motors rotate the inboard links The pat all el spherical five-bar linkage translates those rotations into two dimensional movement of the outboard axis, In unpowered embodiments, two dimensional movement of the outboard axis is translated by the parallel spherical five-bar linkage into rotations of the inboard links Devices such as rotary encoders may sense the bearings of the inboard links and that information may be used to compute the position of the outboard axis Constraining the rotation of an intermediate axis as previously described is advantageous in uupowered embodiments because the constrain! limits the position of the outboard axis to one of the mo possible positions that correspond to the bearings of the inboard links. While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific eonstnictions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art Instead, the embodiments of the invention should be construed according to the claims that follow below

Claims

What is claimed is

1 A robotic arm including a parallel spherical five-bar linkage with a remote center of spherical rotation, the robotic arm comprising an endoscopic camera, two outboard links pivotaily coupled together, at least one of the tw o outboaid links to support the endoscopic camera, tw o inboard Sinks respectively pivotaily coupled to the two outboard links such that the two inboard links are able to cross over one another, the two inboard links to moveabiy support the two outboard link*;, and a ground link pivotaily coupled to the two inboard links, the ground link to moveabiy support the tw o inboaid links

2 The robotic ami of claim 1 , further including two motors coupled by the ground link in spaced apart positions, each of the two motors respectively coupled to one of the two Inboaid links to rotate the coupled mhoatd link and thereb) move the endoscopic camcia about the i emote centei of spherical rotation

3 The robotic arm of claim 2, wherein each of the two motors is respectively coupled to one of the two inboard links h\ a right angle drive

4 The robotic arm of claim 2. further including a first dri\ e shaft coupled to one of the two motors at a driven end and to one of the two inboard lmks at an opposite end, the first drive shaft extending from the dri\ en end toward the remote center of spherical rotation, and a second drive shaft coupled to one of the two motors at a driven end and to one of the

UM> Inboaid links at an opposite end, the second diive shaft extending from the driven end away from the remote center of spherical rotation. such that each of the two inboard Sinks may cross over the ground link

5 I he robotic arm of claim 2. further including a controller coupled to the two motors to provide signals to the motors

6. The robotic ami of claim 5, wherein the controller limits the rotation of the inboard Sinks such that the robotic arm is limited to a range of compact poses,

7. The robotic arm of claim 1, wherein the endoscopic camera is movable along an insertion axis passing through the remote center of spherical rotation.

8. The robotic arm of claim 1 , wherein the two outboard links are constrained to have a minimum an '£g>l»e between them.

9. The robotic arm of claim 4, wherein the minimum angle between the two outboard links is fifteen degrees.

10. The robotic arm of claim 1 , wherein the robotic ami is limited to a range of compact poses.

1 1. A parallel spherical five-bar linkage with a remote center of spherical rotation, the linkage comprising' a ground link having two spaced apart axes of rotation; two inboard links, each inboard link pivotal fy coupled to the ground link at one of the two axes of rotation, each inboard link having an intermediate axis spaced apart from the axis of rotation; two outboard links, each outboard link pivotaϋy coupled to one of the inboard links at the inboard link's intermediate axis, the two outboard links pivotally coupled together at an outboard axis that is spaced apart from the intermediate axes; and a constraint to limit the rotation of the outboard links about the outboard axis such that a minimum angle between the outboard links is at least fifteen degrees; wherein all axes pass through the remote center of spherical rotation and each of the two inboard links is constrained such that the intermediate axis of the inboard link is disposed to a same side of the axis of rotation of the inboard link as the other axis of rotation when the inboard Sinks lies in the same plane as the ground link.

12. The linkage of claim 1 1 , wherein the constraint further includes a mechanical stop.

13. The linkage of claim 12, wherein the mechanical stop directly limits the rotation of one of the outboard links about the outboard axis relative to the other outboard link.

14. The linkage of claim 1 1 , wherein the ground link mά the two inboard Sinks have substantially the same angular length.

15. The linkage of claim 14, wherein the mo outboard links have substantially the same angular length

16. The linkage of claim 14, wherein the two outboard links have substantially the same angular length as the ground link

1 7. The linkage of claim 1 1 , wherein the constraint includes. two motors, each motor coupled to the ground link and to one of the two inboard links at one of the two axes of rotation, and a controller to cause each of the two motors to rotate the coupled inboard link about one of the two axes of rotation with a limited range of rotation.

1 S The linkage of claim 1 1 , w herein the ground link and the two inboard links are constructed and coupled sucli that each one of the two inboard links and its coupled outboard link can freely pass the ground Sink and the other of the two inboard links and its coupled outboard link.

19 The linkage of claim 1 i , further comprising^' two rotary encoders each rotary encoder coupled to one of the inboard link;_* at its axis of rotation; and a computer coupled to the two rotary encoders to receive the bearing of each of the inboard links and compute the position of the outboard axis

20 The linkage of claim 1 1 , wherein one of the outboard links further includes an insertion axis spaced apart from the outboard axis and the intermediate axis, the insertion axis passing through the remote center of spherical rotation

21 I he linkage of claim i 1 , wherein one of the outboard links further includes an insertion axis coincident with the outboard axis, the insertion axis passing through the remote center of spherical rotation.

22. A robotic arm com pri si ng ^■ a first motor coupled to a first axis of rotation, the first axis of rotation extending from the first motor tow ard a remote center of spherical rotation; a second motor coupled to a second axis of rotation, the second axis of rotation extending from the second motor away from the remote center of spherical rotation, a ground link coupled between the first axis of rotation and the second axis of rotation; a first pair of pivoiaily coupled links having a first end coupled to the first axis of rotation such that the first pair of links can pass a first side of the first and second motors; a second pair of pivotaliy coupled links Slaving a first end coupled to the second axis of rotation such that the second pair of links can pass a second side of the first and second motors, the second side of the first and second motors opposite the first side, a second end of the second pair of links pivotaliy coupled to a second end of the first pair of links; wherein ail joints that pivotaliy couple links together allow rotation around an axis that passes through the remote center of spherical rotation.

23. The robotic arm of claim 22, wherein one of the first and second pair of links further includes a support for a surgical instrument having a tool shaft with an insertion axis, the insertion axis being spaced apart from the joint that pivotally couples the first and second pair of links, the insertion axis passing through the remote center of spherical rotation.

24. The robotic arm of claim 23, wherein the joint that pivotaliy couples the first and second pair of links together is between the insertion axis and the first end of the pair of links that includes the support.

25. The robotic arm of claim 23, wherein the insertion axis, a first axis of rotation for the joint that pivotaliy couples the first and second pair of links together, and a second axis of rotation for the joint that pivotaliy couples the pair of links that includes the support are coplanar.

26. The robotic aim of claim 22, wherein the first outboard link further includes a support for a surgical instrument having a tool shaft with an insertion axis, the insertion axis being coincident with the outboard axis, the insertion axis including the remote center of spherical rotation.

27. The robotic arm of claim 22, wherein one of the first and second pair of links further includes a support for a surgical instrument having a too! shaft with an insertion axis, the insertion aλis being coincident with an axis of rotation for the joint that pivotally couples the first and second pair of links together, the insertion axis parsing through the remote center of spherical rotation

28 Tbe robotic arm of claim 22, further comprising a constraint to limit the rotation of the links at the joint that pivotally couples the tlrst and second paii of Hπks such that a minimum angle between the links is at least fifteen de«rees

2^C) The robotic arm of claim 22, furthest comprising a constraint to limit the rotation of the links at the joint that pivαtailv couples the first and second pair of Sinks such that a minimum angle between the links is at least thirty degrees

30 Tbe robotic arm of claim 22, wherein the first motor is coupled to the tlrst axis of rotation at a first angle, and the second motor is coupled to the second axis of rotation at a second angle

31 The robotic arm of claim 22, wherein the first motor is coupled to the fust axis of rotation at a right angle, and the second motor is coupled to the second axis of rotation at a right angle

32 A robotic arm comprising a firbt inboard link coupled to a first axis, of rotation, the first inboard link ha\ ing a first intermediate axis spaced apart from the first axis of rotation, a first outboard link pivotaily coupled to the first inboard link at the first intermediate axis, the first outboard link having an outboard axis spaced apart from the first intermediate axis, a second inboard link couplet! to a second axis of rotation spaced apart from the first axis of rotation, the second inboard link having a second intermediate axis spaced apart from the second axis of rotation; a second outboard link pivotaliy coupled to the second inboard link at the second intermediate axis and to the flr^t outboard link at the outboard axis, a ground link coupling the first axis of rotation to the second axis of rotation, a first motor coupled to the first axis of rotation, a second motor coupled to the second axis of rotation, Λ\ herein the five axes all pass through a remote center of spherical rotation thai is spaced apart from all five links, and a controller to

icie signals to the first and second motors to respective!) rotate the first inboard link and the second inboard Sink such that a first duectional \ ectoi from the first axis of rotation to the first inteimediate axis has the same direction as a second directional vccloi from the first axis of rotation to the second axis of rotation uhen Ae first inboard link lies in the same plane as the ground link, and a third directional %'ector from the second axis of rotation to the second intermediate axis has the same direction as a fourth directional vector from the second axis of rotation to the fust axis of rotation when the second inboard link lies in the same plane as the ground link

33 I he robotic arm of claim 32, \s herein the first outboard Sink further includes a support for a suigical instalment having a tool shaft with an insertion axis, tSic insertion axis being spaced apart from the outboard axis and the first intermediate axis, the insertion axis passing through the t emote center of spheilcal rotation

34 The robotic ami of claim 32, wherein the Insertion axis Is spaced further apart from the first intermediate axis than the outboard axis is spaced apart from the first intermediate axis

35 The robotic arm of claim 34, wherein the insertion axis, the outboard axis, and the first intermediate axis are copianar

36 The robotic ami of claim 32, therein the first outboard link further includes a support foi a surgical instrument having a tool shall with an insertion avis, the insertion axis being coincident with the outboaid axis, tiie insertion axis including the remote center of spherical rotation

37 The robotic arm of claim 32, further comprising a constraint to limit the rotation of the first outboard Sink about the outboard axis, s>uch that a minimum angle between the first outboard link and the second outboard link is at least fifteen degrees

38 The robotic arm of claim 32, further comprising a constraint to limit the rotation of the first outboard link about the outboard axis such that a minimum angle between the first outboard link and the second outboard link is at least thirty degrees

39. The robotic arm of claim 32, wherein the first motor is coupled to the first inboard link at a first angle to the first axis of rotation, and the second motor is coupled to the second inboard link at a second angle to the second axis of rotation

40. The robotic arm of claim 32, wherein the first motor is coupled to the first inboard link at a right angle to the first axis of rotation, and the second motor is coupled to the second inboard link at a right angle to the second axis of rotation.

41. The robotic arm of claim 40, further comprising; a first drive shaft coupled to the first motor at a driven end and to the first inboard link at an opposite end, the first drive shaft extending from the driven end toward the remote center of spherical rotation; and a second drive shall coupled to the second motor at a driven end and to the second inboard link at an opposite end, the second drive shaft extending from the driven end away from the remote center of spherical rotation.

42. A system comprising: a first robotic arm including a first parallel spherical five-bar linkage having a ground link; two motors coupled to the ground link, each motor having an axis of rotation, the two axes of rotation intersecting at a first remote center of spherical rotation, two inboard links, each inboard link coupled to one of the motors at the motor's axis of rotation, each inboard link having an intermediate axis spaced apart from the motor's axis of rotation, the two intermediate axes passing through the first remote center of spherical rotation, and two outboard links, each outboard link pivotaliy coupled to one of the inboard links at the inboard link's intermediate axis, the two outboard links pivotaliy coupled together at an outboard axis that is spaced apart from the intermediate axes and passing through the first remote center of spherical rotation; and a controller to cause each of the two motors of the first robotic arm to rotate the respectively coupled inboard links about the motors' axes of rotation such that the two intermediate axes are on the same side of a plane that includes the outboard axis and the axis of rotation of either one of the motors,

T he system of claim 42, wherein one of the outboard links further includes a surgical instrument hax ing an insertion axis spaced apart from the outboard axis, the insertion axis passing through the first remote center of spherical rotation

Tbe system of claim 43, u herein the insertion axis is spaced further apart ftorn the intermediate axis of the one of the outboard links than the outboard axis is spaced apart from that intermediate axis

The system of claim 44. wherein the insertion axis, the outboard avis, and the intermediate axis of the one of the outboard links are coplanar

The system of claim 42, wherein one of the outboard links further includes a surgical instrument having an insertion axis coincident with the outboard axis, the insertion axis passing through the first remote center of spherical rotation

The system of claim 42. wherein the first robotic aπn further includes a mechanical stop to limit the rotation of one of the outboard links about the intermediate axis such that an angle between the motor's axis of rotation, the intermediate axis, and the outboard axis cannot exceed 160 degrees

The system of claim 42, wherein the first robotic arm further includes a mechanical stop to limit the rotation of one of the outboard links, about the intet mediate axis such that an angle between the motor's axis of rotation, the intermediate axis., and the outboard axis cannot exceed 120 de -eg>r>ees

I he system of claim 42, wherein the mo axes of rotation are spaced apart on the ground link

The system (if claim 42, wherein the

axes of rotation ate coincident on the gtound link

Tbe system of claim 42, further comprising a second robotic aπn including a second parallel spherical tϊve-ba? linkage having two motors, each motor having an axis of rotation, the two axes of rotation intersecting at a second remote center of spherical rotation, two inboard links each inboard link coupled to one of the motors at the motor's axis of rotation, each inboard Sink having an intermediate axis spaced apart from the motor's axis of rotation, the two intermediate axes passing through the second remote center of spherical rotation, and two outboard links, each outboard link pivotally coupled to one of the inboard links at the inboard link's intermediate axis, the two outboard links pivotally coupled together at an outboard axis that is spaced apart from the intermediate axes and passing through the second remote center of spherical rotation; the controller to further cause each of the two motors of the second robotic arm to rotate the respectively coupled inboard links about the motors' axes of rotation such that the two intermediate axes are on the same side of a plane that includes the outboard axis and one of the axes of rotation, and further such that the two intermediate axes of the second robotic arm are on the opposite side of the plane as they would be for the first, robotic arm.

52. A robotic arm for a minimally invasive surgical system, the robotic arm comprising: a parallel five-bar spherical linkage having a range of compact poses, the parallel five- bar spherical linkage to spherically rotationally move a robotic surgical tool coupled to the parallel five-bar spherical linkage about a remote center of spherical rotation; and a constraint coupled to the robotic arm, the constraint to limit the parallel five-bar spherical linkage to the range of compact poses

53. The robotic arm of claim 52, wherein the robotic arm includes a first motor and a second motor to provide two parallel rotary motion inputs to the parallel five-bar spherical linkage; and the constraint is a controller coupled to the first motor and the second motor to control the parallel five-bar spherical linkage to maintain the range of compact poses.

54. The robotic aim of claim 52, wherein the parallel five-bar spherical linkage has an outboard joint, and the constraint includes a mechanical stop coupled to the a.n outboard joint to limit the parallel five-bar spherical linkage to the range of compact poses.

55. The robotic arm of claim 52, wherein the robotic arm further includes a ground link; the first pair of links is coupled at a first, end of the first pair of links to the ground link; the second pair of serial pivotal Sy coupled links is coupled at a first end of the second pair of links to the ground link; and a second end of the first pair of links and a second end of the second pair of links are coupled together at an outboard joint.

56. The robotic arm of claim 52, wherein the first pair of links and the second pair of links have arcuate shapes lying on a plurality of spheres of differing radii .

57. The robotic arm of claim 52, wherein the constraint provides clearance for other surgical equipment around the robotic arm.

58. The robotic arm of claim 52, wherein the parallel five-bar spherical linkage has a ground link to couple to a table to support the robotic arm over a patient

59. The robotic arm of claim 58, further comprising: a set-up ami coupled between the parallel five-bar spherical linkage and the table to support the robotic arm over a patient,

60. A method for a robotic arm in a minimally invasive surgical system, the method comprising: posing a parallel five-bar spherical linkage into a compact pose; moving the parallel five-bar spherical linkage with a spherical motion about a remote center of spherical rotation; and constraining the spherical motion of the parallel five-bar spherical linkage within a range of compact poses.

61. The method of claim 60, wherein points of the parallel five-bar spherical linkage move over differing spherical surfaces to spherically move the parallel five-bar spherical linkage.

62. The method of claim 60, wherein the method further includes coupling a link of the parallel five-bar spherical linkage to a table to support the robotic arm over a patient. I he method of claim 60, further comprising coupling a link of the parallel five-bar spherical linkage to a table with & set-up ami to support the robotic arm over a patient

Tbe method of claim 60. wheiein the iobotic aim has a first motor and a second motor coupled to the paiailel fn c-bar spherical linkage, and in constraining the spherical motion of the parallel five-bar spherical linkage within the range of compact poses, controlling the first motor and the second motor to constrain the spherical motion of the parallel five-bar spherical linkage within the range of compact poses