Robot with following operation of end effector

Abstract

To provide a robot with a following operation of an end effector so as to increase throughput and a capacity factor of a related facility as well as reducing a cycle time by the minimization of a transfer time.SOLUTION: In a robot 28 having a robot driving device and a robot arm mechanism 30, a first link (upper arm) 34 of the robot arm mechanism is connected to the robot driving device in a first driving shaft, and a second link (front arm) 36 is coupled to an upper arm in a rotational joint 46, and can be rotated around the rotational joint. The rotational joint can be driven by a first band mechanism 48 coupled to a second driving shaft, an end effector 38 is coupled to the front arm by a rotational joint 56, and can be rotated to a circumference of the rotational joint 56. The rotational joint 56 can be driven by a second band mechanism 58 coupled to the first rotational joint, and the second band mechanism provides a variable transfer ratio.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The illustrative and non-limiting embodiments relate generally to robots with end effectors, and more particularly to robots with driven motion of the end effectors.

[0002] Vacuum, atmospheric, and controlled environment processing for applications such as those associated with semiconductor, LED (Light Emitting Diode), solar, MEMS (Micro Electro Mechanical Systems), or other device manufacturing utilizes robotics and other forms of automation to transport substrates, and carriers associated with substrates, to or from storage, processing, or other locations. Such transport of substrates may move individual substrates, groups of substrates, using a single arm carrying one or more substrates, or using multiple arms each carrying one or more substrates. Much of the manufacturing, such as that associated with semiconductor manufacturing, is performed in clean or vacuum environments where footprint and volume are at a premium. Furthermore, much of the automated transport is implemented where minimizing transport time results in reduced cycle times and increased throughput and utilization of the associated equipment. Abstract

[0003] The following summary is provided by way of example only and is not intended to limit the scope of the claims.

[0004] In one example, a drive unit having at least three drive motors and at least three coaxial drive shafts respectively connected to the at least three drive motors; With a robotic arm; wherein the robot arm comprises: an upper arm connected to a first drive shaft of the at least three coaxial drive shafts; a first forearm coupled to the upper arm at a first revolute joint; a second forearm coupled to the upper arm at a second revolute joint coaxial with the first revolute joint; a first end effector coupled to the first forearm at a third revolute joint and rotatable about the third revolute joint; a second end effector coupled to the second forearm at a fourth revolute joint and rotatable about the fourth revolute joint; Equipped with At least one of the upper arm, the first forearm, and the second forearm includes a band mechanism having at least one pulley with a non-circular outer diameter, the band mechanism comprising: Between one of the first to fourth rotational joints and another one of the first to fourth rotational joints, or Between one of the first to fourth rotary joints and one of the at least three coaxial drive shafts, Located in; The band mechanism is configured to provide a variable transmission ratio, wherein the variable transmission ratio is selected such that an orientation of the first end effector changes in a predetermined manner as a function of a position of the first forearm relative to the upper arm, and wherein the variable transmission ratio is selected such that when the upper arm and the first forearm are actuated, a reference point on the first end effector can follow a predetermined path with predetermined and varying orientations.

[0005] In another example, a transport apparatus is provided that includes a drive unit having at least three drive motors and at least three coaxial drive shafts respectively connected to the at least three drive motors, and a robot arm, wherein the robot arm includes: an upper arm connected to a first drive shaft of the at least three coaxial drive shafts; a first forearm coupled to the upper arm at a first revolute joint; a second forearm coupled to the upper arm at a second revolute joint spaced from the first revolute joint; a first end effector coupled to the first forearm at a third revolute joint and rotatable about the third revolute joint; a second end effector coupled to the second forearm at a fourth revolute joint and rotatable about the fourth revolute joint; Equipped with At least one of the upper arm, the first forearm, and the second forearm includes a band mechanism having at least one pulley with a non-circular outer diameter, the band mechanism comprising: Between one of the first to fourth rotational joints and another one of the first to fourth rotational joints, or Between one of the first to fourth rotary joints and one of the at least three coaxial drive shafts, Located in; The band mechanism is configured to provide a variable transmission ratio, wherein the variable transmission ratio is selected such that an orientation of the first end effector changes in a predetermined manner as a function of a position of the first forearm relative to the upper arm, and wherein the variable transmission ratio is selected such that when the upper arm and the first forearm are actuated, a reference point on the first end effector can follow a predetermined path with predetermined and varying orientations.

[0006] In another example, a robot includes a drive unit having at least one motor and at least one drive shaft connected to the at least one motor; and a robot arm. wherein the robot arm comprises: at least one upper arm connected to the at least one drive shaft; a first forearm connected to the at least one upper arm at a first revolute joint; a second forearm connected to the at least one upper arm at a second revolute joint; a first end effector connected to the first forearm at a third revolute joint and rotatable about the third revolute joint; a second end effector connected to the second forearm at a fourth revolute joint and rotatable about the fourth revolute joint; Equipped with At least one of a first upper arm or a first forearm of the at least one upper arm has a mechanism therein configured to provide a variable transmission ratio, wherein the variable transmission ratio is selected such that an orientation of the first end effector changes in a predetermined manner as a function of a position of the first forearm relative to the first upper arm, and wherein the variable transmission ratio is selected in such a way that when the first upper arm and the first forearm are actuated, a reference point on the first end effector can follow a predefined path with predefined and varying orientations.

[0007] In another example, an apparatus includes a drive and a robotic arm. The drive includes a first drive shaft rotatable about a first axis of rotation and a second drive shaft rotatable about a second axis of rotation, the second drive shaft being coaxial with the first drive shaft, partially internal to the first drive shaft, and axially rotatable within the first drive shaft. The robotic arm includes an upper arm connected to the drive at the first drive shaft, a forearm coupled to the upper arm, and an end effector coupled to the forearm, the forearm coupled to the upper arm at a first revolute joint and rotatable about the first revolute joint, the first revolute joint being drivable by a first band mechanism coupled to the second drive shaft, the end effector coupled to the forearm at a second revolute joint and rotatable about the second revolute joint, the second revolute joint being drivable by a second band mechanism coupled to the first revolute joint. The second band mechanism is configured to provide a variable transmission ratio. In another example, an apparatus includes a drive and a robotic arm, the drive including a first drive shaft rotatable about a first axis of rotation, a second drive shaft rotatable about a second axis of rotation, and a third drive shaft rotatable about a third axis of rotation, the second drive shaft being coaxial with, partially within, and axially rotatable within the first drive shaft, and the third drive shaft being coaxial with, partially within, and axially rotatable within the second drive shaft. The robot arm comprises an upper arm connected to the drive device at the first drive shaft, a forearm coupled to the upper arm, and a first end effector and a second end effector coupled to the forearm, the forearm being coupled to the upper arm at a first rotary joint and rotatable about the first rotary joint, the first rotary joint being drivable by a single stage band mechanism, the single stage band mechanism comprising a first shoulder pulley drivable by the third drive shaft, a first elbow pulley partially forming the first rotary joint, and a band, belt, or cable configured to transfer motion between the first shoulder pulley and the first elbow pulley, the first end effector and the second end effector being coupled to the forearm at a second rotary joint, and orientations of the first end effector and the second end effector being controlled via a two stage band mechanism. The first stage of the two-stage band mechanism includes a second shoulder pulley drivable by the second drive shaft, a second elbow pulley forming in part the first revolute joint, and an upper band, belt or cable configured to transfer motion between the second shoulder pulley and the second elbow pulley.The second stage of the two stage band mechanism includes a third elbow pulley coupled to the second elbow pulley, a first wrist pulley coupled to the first end effector, and a first lower band, belt, or cable configured to transfer motion between the third elbow pulley and the first wrist pulley, and the second stage of the two stage band mechanism further includes a fourth elbow pulley coupled to the second elbow pulley, a second wrist pulley coupled to the second end effector, and a second lower band, belt, or cable configured to transfer motion between the fourth elbow pulley and the second wrist pulley. At least one of the motion between the first shoulder pulley and the first elbow pulley, the motion between the second shoulder pulley and the second elbow pulley, the motion between the third elbow pulley and the first wrist pulley, and the motion between the fourth elbow pulley and the second wrist pulley is performed with a variable transmission ratio. In another example, an apparatus includes a drive, a first robotic arm, and a second robotic arm, the drive including a first drive shaft rotatable about a first axis of rotation, a second drive shaft rotatable about a second axis of rotation, and a third drive shaft rotatable about a third axis of rotation, the second drive shaft being coaxial with, partially within, and axially rotatable within the first drive shaft, and the third drive shaft being coaxial with, partially within, and axially rotatable within the second drive shaft. The first robot arm comprises a first upper arm connected to the drive device at the first drive shaft, a first forearm coupled to the first upper arm, and a first end effector coupled to the first forearm, wherein the first forearm is coupled to the first upper arm at a first rotary joint, the first rotary joint being drivable by the second drive shaft using a first band mechanism, and the first end effector is coupled to the first forearm at a third rotary joint, the third rotary joint being drivable by the first rotary joint using a third band mechanism. The second robot arm includes a second upper arm connected to the drive device at the third drive shaft, a second forearm coupled to the second upper arm, and a second end effector coupled to the second forearm, the second forearm coupled to the second upper arm at a second rotary joint, the second rotary joint being drivable by the second drive shaft using a second band mechanism, the second end effector coupled to the second forearm at a fourth rotary joint, the fourth rotary joint being drivable by the second rotary joint using a fourth band mechanism, and at least one of the first band mechanism, the second band mechanism, the third band mechanism, and the fourth band mechanism has a variable transmission ratio. The foregoing aspects and other features are explained in the following description, which refers to the accompanying drawings, in which: [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a top view of the transport device.

[0009] [Diagram 2] FIG. 2 is a top view of the transport device.

[0010] [Diagram 3] FIG. 3 is a side view of the transport device.

[0011] [Figure 4] FIG. 4 is a top view of the transport device.

[0012] [Diagram 5] FIG. 5 is a top view of the transport device.

[0013] [Figure 6] FIG. 6 is a top view of the transport device.

[0014] [Figure 7] FIG. 7 is a top view of the transport device.

[0015] [Figure 8] FIG. 8 is a top view of the transport device.

[0016] [Figure 9] FIG. 9 is a side view of the transport device.

[0017] [Figure 10] FIG. 10 is a top view of the transport device.

[0018] [Figure 11] FIG. 11 is a top view of the transport device.

[0019] [Figure 12] FIG. 12 is a side view of the transport device.

[0020] [Figure 13] 13A to 13C are top views of the transport apparatus.

[0021] [Figure 14A] FIG. 14A is a top view of the transport device.

[0022] [Figure 14B] FIG. 14B is a side view of the transport device.

[0023] [Figure 15] 15A to 15C are top views of the transport apparatus.

[0024] [Figure 16] FIG. 16 is a top view of the transport device.

[0025] [Figure 17] FIG. 17 is a side view of the transport device.

[0026] [Figure 18A] FIG. 18A is a top view of the transport apparatus.

[0027] [Figure 18B] FIG. 18B is a side view of the transport device.

[0028] [Figure 19] 19A to 19C are top views of the transport apparatus.

[0029] [Figure 20] 20A to 20C are top views of the transport device.

[0030] [Figure 21] 21A to 21C are top views of the transport apparatus.

[0031] [Figure 22] FIG. 22 is a side view of the transport device.

[0032] [Diagram 23] FIG. 23A is a side view of the transport device.

[0033] FIG. 23B is a side view of the transport device.

[0034] [Figure 24] FIG. 24 is a side view of the transport device.

[0035] [Diagram 25] FIG. 25A is a top view of the transport apparatus.

[0036] FIG. 25B is a side view of the transport device.

[0037] [Figure 26] 26A to 26C are top views of the transport apparatus.

[0038] [Figure 27] 27A to 27C are top views of the transport apparatus.

[0039] [Figure 28] 28A to 28C are top views of the transport apparatus.

[0040] [Figure 29A] FIG. 29A is a top view of the transport apparatus.

[0041] [Figure 29B] FIG. 29B is a side view of the transport device.

[0042] [Diagram 30] FIG. 30A is a side view of the transport device.

[0043] FIG. 30B is a side view of the transport device.

[0044] [Diagram 31] FIG. 31 is a top view of the transport device.

[0045] [Diagram 32]FIG. 32 is a side view of the transport device.

[0046] [Figure 33A] FIG. 33A is a top view of the transport apparatus.

[0047] [Figure 33B] FIG. 33B is a side view of the transport device.

[0048] [Diagram 34] 34A to 34C are top views of the transport apparatus.

[0049] [Diagram 35] 35A to 35C are top views of the transport apparatus.

[0050] [Diagram 36] FIG. 36 is a side view of the transport device.

[0051] [Figure 37A] FIG. 37A is a top view of the transport apparatus.

[0052] [Figure 37B] FIG. 37B is a side view of the transport device.

[0053] [Figure 38A] FIG. 38A is a top view of the transport apparatus.

[0054] [Figure 38B] FIG. 38B is a side view of the transport device.

[0055] [Figure 39] FIG. 39 is a top view of the transport device.

[0056] [Diagram 40] FIG. 40 is a side view of the transport device.

[0057] [Figure 41A] FIG. 41A is a top view of the transport device.

[0058] [Figure 41B] FIG. 41B is a side view of the transport device.

[0059] [Figure 42A] FIG. 42A is a partial outline view of a pulley.

[0060] [Fig. 42B-42E] 42B to 42E are top views of the transport apparatus.

[0061] [Diagram 43] FIG. 43 is a partial outline view of a pulley.

[0062] [Diagram 44] FIG. 44 is a top view of the transport device.

[0063] [Diagram 45] FIG. 45 is a diagram of the shaft position trajectory.

[0064] [Figure 46] FIG. 46 is a top view of the transport device.

[0065] [Figure 47] FIG. 47 is a diagram of the shaft position trajectory.

[0066] [Figure 48] FIG. 48 is a side view of the transport device.

[0067] [Figure 49A] FIG. 49A is a top view of the transport apparatus.

[0068] [Figure 49B] FIG. 49B is a side view of the transport device.

[0069] [Figure 50] FIG. 50 is a top view of the transport device.

[0070] [Figure 51] FIG. 51 is a diagram of the shaft position trajectory.

[0071] [Figure 52] FIG. 52 is a top view of the transport device.

[0072] [Diagram 53] FIG. 53 is a diagram of the shaft position trajectory. Detailed Description of the Embodiments

[0073] Referring to FIG. 1, a top view of a transport apparatus 10 having features of an exemplary embodiment is shown. These features are described with reference to the exemplary embodiment shown in the drawings, but it should be understood that they may be realized by various other embodiments. Also, any suitable size, shape, or type of elements and materials may be used. A multi-link robot arm mechanism is disclosed herein. A three-link robot arm mechanism is disclosed that may be used to transport material to and from parallel, e.g., laterally offset, stations in, for example, a semiconductor wafer processing tool.

[0074] An exemplary arrangement of a semiconductor wafer processing tool 10 is shown diagrammatically in a top view in FIG. 1. In this particular example, the tool features four sets of parallel stations, e.g., a set of load locks 12, and three sets of process module stations 14, 16, 18. As shown in the example of FIG. 1, the present three-link arm mechanism is designed to access each station in the tool along a predefined path, e.g., a substantially linear path, and with a predefined end effector orientation, e.g., along linear path 20. These linear paths may be parallel to each other in any plane 22 or may be at an angle to each other. In alternative embodiments, any suitable path or combination of paths may be defined, such as linear, circular, or any suitable shape or combination of shapes.

[0075] FIG. 2 shows a top view and FIG. 3 shows a side view of a robot arm mechanism 30 according to a disclosed embodiment mounted on a robot drive 32. The arm mechanism may be comprised of a first link (upper arm) 34, a second link (forearm) 36, and a third link (end effector) 38 that supports a substrate 40. An exemplary internal mechanism of the robot 28 is shown diagrammatically in FIG. 3. The arm mechanism may be driven by a two-axis spindle with two coaxial shafts, for example an outer T1 shaft 42 and an inner T2 shaft 44. The inner T2 shaft 44 may be partially inside the outer T1 shaft 42 such that the inner T2 shaft 44 is rotatable within the outer T1 shaft 42. The first link 34 of the robot arm mechanism may be directly attached to the T1 shaft 42. The second link 36 may be coupled to the first link 34 via a revolute joint 46 and driven by the T2 shaft 44 using a band mechanism 48. The band mechanism 48 may include a shoulder pulley 50, an elbow pulley 52, and a band, belt, or cable 54. The shoulder pulley 50 may be attached to the T2 shaft 44, and the elbow pulley 52 may be attached to the second link 36, and the band, belt, or cable 54 may transmit motion between the two pulleys 50, 52. The belt mechanism may feature a fixed transmission ratio, for example, a 1:1 ratio may be conveniently used, although any other suitable mechanism may be used. The third link 38 may be coupled to the second link 36 via a revolute joint 56, and the orientation of the third link 38 may be constrained by another band mechanism 58. The band mechanism 58 may include an elbow pulley 60, a wrist pulley 62, and a band, belt, or cable 64. An elbow pulley 60 may be connected to the first link 34, a wrist pulley 62 may be connected to the third link 38, and a band, belt, or cable 64 may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, by using at least one pulley having a non-circular profile. By way of example, and referring to FIG. 3, the wrist pulley may feature a non-circular profile.An example of an arm using non-circular pulleys is disclosed in U.S. Patent Application Serial No. 13 / 833,732, entitled "Robot Having Arm With Unequal Link Lengths," filed March 15, 2013, which is incorporated herein by reference in its entirety.

[0076] The variable transmission ratio may be selected to change the orientation of the third link (end effector) 38 in a predefined manner as a function of the relative position of the first link 34 and the second link 36. The relative position of the first link 34 and the second link 36 may conveniently be expressed as an indented angle between the two links. Alternatively, the orientation of the third link (end effector) 38 may change in a predefined manner as a function of the relative positions of the links, shafts, etc. As an example, the transmission ratio may be selected such that when the first link and the second link are respectively actuated, a reference point on the third link (usually the nominal center 70 of the end effector) follows a predefined path, with a predefined (but not necessarily constant) orientation of the third link (end effector). As an example, the paths 72, 74, 76, 78 may be selected as access paths to any of the stations of FIG. 1, as shown in FIG. 4. The transmission ratio may also be selected to allow the arm to access the neighboring station 82, as shown in FIG. 5. As shown in FIGS. 6 and 7, the T1 shaft 42 and the T2 shaft 44 may be rotated to reorient the arm mechanism to access a different set of stations 86, 88 or 90, 92.

[0077] It should be noted that although the initial position of the robot arm mechanism is shown on the axis of symmetry between adjacent parallel stations, any other initial position may be used. The robot drive may also feature additional axes to facilitate vertical elevation of the arm mechanism, e.g., lifting or placing a wafer carried by the end effector. In another embodiment, other additional rotational axes and / or arms may be provided. In another embodiment, a band mechanism between a shoulder pulley attached to the T2 shaft and an elbow pulley attached to the second link features a variable transmission ratio, e.g., with at least one non-circular pulley. The variable transmission ratio is selected such that the extension of the arm is driven by the T1 shaft, while the T2 shaft remains stationary. In another embodiment, the variable transmission ratio may be selected such that the T2 shaft follows a predefined motion profile as the robot arm extends along a predefined path. In another embodiment, the mechanism for constraining the orientation of the third link includes an additional band mechanism.

[0078] For example, as shown diagrammatically in FIG. 8, the orientation of the third link 102 may be constrained by a band mechanism 104. The band mechanism 104 may include an elbow pulley 106, a wrist pulley 114, and a band, belt, or cable 116. The elbow pulley 106 may be coaxial with an elbow joint 108 (a rotational joint between the first link and the second link) and may rotate freely with respect to the two links, the first link 110 and the second link 112. The wrist pulley 114 may connect to the third link 102. The band, belt, or cable 116 may transmit motion between the two pulleys. The motion of the elbow pulley is constrained by another band mechanism 118. The band mechanism 118 may include a pulley 120, a pulley 124, and a band, belt, or cable 126. Pulley 120 is attached to the T2 shaft 122, pulley 124 is attached to the elbow pulley 106, and a band, belt, or cable 126 may transmit motion between these two pulleys. The two band mechanism may feature a constant or variable transmission ratio. As an example, if the two band mechanism features a constant ratio of 1:1 and the second link is coupled to the T2 shaft, the end effector will maintain a constant orientation as the arm extends and retracts due to the actuation of the T1 shaft.

[0079] The disclosed aspects are similarly applicable to dual end effector arm mechanisms that may be used for material transfer to and from parallel (laterally offset) stations in a semiconductor wafer processing tool, where an exemplary arrangement of a semiconductor wafer processing tool 210 is shown generally in a top view in Figure 10. In this particular example, the tool features four parallel stations, e.g., a set of load locks 220, three sets of process module stations 230, and a transfer chamber or module 232.

[0080] As shown in the example of FIG. 10, the arm mechanism of this embodiment may be designed to access each station in the tool along a predefined path 236, e.g., a substantially straight path, and with a predefined end effector orientation, e.g., an orientation along the straight path.

[0081] FIG. 11 shows a top view and FIG. 12 shows a side view of a robot arm mechanism 250 attached to a robot drive 252. The arm mechanism may consist of a first link (upper arm) 254, a second link (forearm) 256, a pivoting end effector A 258, and a pivoting end effector B 260. An exemplary internal mechanism of the robot is shown diagrammatically in FIG. 11 and FIG. 12. The arm mechanism may be driven by a three-axis spindle with three coaxial shafts, for example, an outer T1 shaft 262, a T2 shaft 264, and an inner T3 shaft 266. The T2 shaft 264 may be partially inside the outer T1 shaft 262, and the inner T3 shaft 266 may be partially inside the T2 shaft 264. The first link of the robot arm mechanism may be attached directly to the T1 shaft. The second link may be coupled to the first link via a revolute joint (elbow joint) and driven by the T3 shaft using a band mechanism. The band mechanism may comprise a first shoulder pulley, a first elbow pulley, and a band, belt, or cable. The first shoulder pulley may be attached to the T3 shaft, and the first elbow pulley may be attached to the second link, and the band, belt, or cable may transmit motion between these two pulleys. The band mechanism may feature a fixed or variable transmission ratio, for example, a 1:1 ratio may be conveniently used, although any other suitable mechanism may be used. End effector A may be coupled to the second link via a revolute joint (wrist joint), and the orientation of end effector A may be controlled by a two-stage band mechanism. The first stage of the band mechanism may comprise a second shoulder pulley, a second elbow pulley, and a band, belt, or cable. The second shoulder pulley may be connected to the T2 shaft, and the band, belt, or cable may transmit motion between these two pulleys. The first stage of the band mechanism may feature a fixed or variable transmission ratio, for example a 1:1 ratio may be conveniently used. The second stage of the band mechanism may include a third elbow pulley, a first wrist pulley and a band, belt or cable.The third elbow pulley may be connected to the second elbow pulley, and the first wrist pulley may be connected to the end effector A, and a band, belt, or cable may transmit motion between these two pulleys. The second stage of this band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, by using at least one pulley having a non-circular profile. By way of example, and referring to FIG. 11 and FIG. 12, the wrist pulley may feature a non-circular profile. An example of an arm using a non-circular pulley is disclosed in U.S. Patent Application Serial No. 13 / 833,732, entitled "Robot Having Arm With Unequal Link Lengths," filed March 15, 2013, which is incorporated herein by reference in its entirety. Another example of an arm using non-circular pulleys is disclosed in U.S. Provisional Patent Application No. 62 / 132,066, entitled "2-Degree-of-Freedom 3-Link Robot Arm Mechanisms," filed March 12, 2015, which is incorporated herein by reference in its entirety.

[0082] The variable transmission ratio may be selected to change the orientation of end effector A in a predefined manner as a function of the relative positions of the first link, the second link, and the T2 shaft. For example, the variable transmission ratio may be selected to make end effector A follow a path to the station, as shown in Figs. 13A-13C, or to fold laterally in response to the motion of the T2 shaft, also shown in Figs. 13A-13C. Similarly, end effector B may be coupled to the second link via a revolute joint (wrist joint), and the orientation of end effector B may be controlled by a two-stage band mechanism. The first stage of this band mechanism is common to end effector A. The second stage of this band mechanism may include a fourth elbow pulley, a second wrist pulley, and a band, belt, or cable. The fourth elbow pulley may be connected to the second elbow pulley, and the second wrist pulley may be connected to end effector B, and the band, belt, or cable may transmit the motion between these two pulleys. The second stage of the band mechanism may be configured in a cross-like manner as shown in Figs. 11 and 12 and may feature a variable transmission ratio. The variable transmission ratio may be realized, for example, by using at least one pulley with a non-circular profile. By way of example, with reference to Figs. 11 and 12, the wrist pulley may feature a non-circular profile. The variable transmission ratio may be selected to change the orientation of the end effector B in a predefined manner as a function of the relative positions of the first link, the second link, and the T2 shaft. For example, the variable transmission ratio may be selected so that the end effector B follows a path to the station, as shown in Figs. 13A to 13C, or folds laterally in response to the movement of the T2 shaft, also shown in Figs. 13A to 13C.

[0083] Although the arm mechanism is shown as right-handed (with the elbow joint on the right side of the line from the shoulder joint to the wrist joint) when accessing the left-hand stations in FIGS. 13A-13C and left-handed when accessing the right-hand stations in FIGS. 13A-13C, in alternative embodiments the arm mechanism may be configured to be left-handed when accessing the left-hand stations and right-handed when accessing the right-hand stations.

[0084] In yet another embodiment, the second link may be driven by the T2 shaft and the orientation of the end effector may be controlled by the T3 shaft. Referring to FIG. 14A and FIG. 14B, a top view and a side view, respectively, of a robot arm mechanism 300 mounted on a robot drive 302 are shown. An exemplary internal mechanism of the robot is also included. The arm mechanism may be comprised of a left linkage 304 and a right linkage 306. The arm mechanism may be driven by a three-axis spindle with three coaxial shafts, for example, an outer T1 shaft 308, a T2 shaft 310, and an inner T3 shaft 312. The T2 shaft 310 may be partially inside the outer T1 shaft 308 and the inner T3 shaft 312 may be partially inside the T2 shaft 310. The left linkage may be comprised of a first left link (upper arm) 314, a second left link (forearm) 316, and a third left link (end effector) 318. The first left link may be directly attached to the T1 shaft. The second left link may be coupled to the first left link via a revolute joint and constrained by the T2 shaft using a band mechanism. The band mechanism may include a first shoulder pulley, a left elbow pulley, and a band, belt, or cable. The first shoulder pulley may be attached to the T2 shaft and the left elbow pulley may be attached to the second link, and the band, belt, or cable may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio. However, any other suitable mechanism may be used. The third left link may be coupled to the second left link via a revolute joint and the orientation of the third left link may be constrained by another band mechanism. The band mechanism may include a left elbow pulley, a left wrist pulley, and a band, belt, or cable. The left elbow pulley may be connected to the first left link and the left wrist pulley may be attached to the third left link, and the band, belt, or cable may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, by using at least one pulley having a non-circular profile.By way of example, and referring to Figures 14A and 14B, the wrist pulley may feature a non-circular profile. The variable transmission ratio may be selected to change the orientation of the third left link (end effector) in a predefined manner as a function of the relative position of the first left link and the second left link. The relative position of the first left link and the second left link may be conveniently expressed as an indentation angle between the two links. For example, the transmission ratio of the two band mechanisms may be selected such that, when the first left link is driven by the T1 shaft and the T2 shaft remains stationary, a reference point on the third left link (usually the nominal center of the end effector) follows a predefined path, keeping the orientation of the third left link (end effector) predefined (e.g., constant).

[0085] As an example, a path may be selected as an access path to one of the stations of FIG. 10, as shown in FIG. 15A-15C. Referring again to FIG. 14A and FIG. 14B, the right linkage may be substantially configured as a mirror image of the left linkage. The right linkage may be comprised of a first right link (upper arm) 320, a second right link (forearm) 322, and a third right link (end effector) 324. The first right link may be attached directly to the T3 shaft. The second right link may be coupled to the first right link via a revolute joint and constrained by the T2 shaft using a band mechanism. This band mechanism may comprise a second shoulder pulley, a right elbow pulley, and a band, belt, or cable. The second shoulder pulley may be attached to the T2 shaft, the right elbow pulley may be attached to the second link, and the band, belt, or cable may transmit motion between these two pulleys. As with the left linkage, the belt mechanism may feature a variable transmission ratio. However, any other suitable mechanism may be used.

[0086] The remaining components of the right linkage may be configured substantially as a mirror image of the left linkage, with the operation of the right linkage being substantially equivalent to the mirrored operation of the left linkage. Additionally, the T1, T2, and T3 shafts may be rotated synchronously to reorient the arm mechanism to access a different set of stations.

[0087] Although the left linkage is shown as left-handed (with the elbow joint on the left side of the line from the shoulder joint to the wrist joint) in Figures 15A-15C and the right linkage is shown as right-handed in Figures 15A-15C, in alternative embodiments the mechanism may be configured so that the left linkage is right-handed and the right linkage is left-handed.

[0088] In yet another embodiment, the right upper arm may be driven by the T2 shaft, and the orientation of the left and right forearms may be constrained by the T3 shaft.

[0089] The disclosed embodiments are similarly applicable to dual end effector robot arm mechanisms that may be used for material transfer to and from parallel (laterally offset) stations in a semiconductor wafer processing tool. An exemplary layout of a semiconductor wafer processing tool 410 is shown generally in a top view in Figure 16. In this particular example, the tool features four parallel stations, e.g., a set of load locks 412 and three process module stations 414 coupled to a transfer chamber 416.

[0090] As shown in the example of FIG. 16, the disclosed arm mechanism may access each station in the tool along a predefined path, e.g., substantially linear paths 418, 420, and with a predefined end effector orientation, e.g., orientation along linear paths 418, 420.

[0091] FIG. 17 shows a side view of a robot 50 with an exemplary robot arm mechanism 452 according to an embodiment attached to a robot drive 454. The arm mechanism may be composed of a first link (upper arm) 456, a second link (forearm) A 458, an end effector A 460, a second link (forearm) B 462, and an end effector B 464. An exemplary internal mechanism of the robot 450 of FIG. 17 is shown diagrammatically in FIG. 18A and FIG. 18B. The arm mechanism may be driven by a three-axis spindle 454 with three coaxial shafts, e.g., an outer T1 shaft 470, a T2 shaft 472, and an inner T3 shaft 474. The first link 456 of the robot arm mechanism may be directly attached to the T1 shaft 470. The second link A 458 may be coupled to the first link 456 via a revolute joint (elbow joint) 480 and driven by the T3 shaft 474 using a band mechanism 482. The band mechanism 482 may comprise a shoulder pulley A 484, an elbow pulley A 486, and a band, belt, or cable 488. The shoulder pulley A 484 may be attached to the T3 shaft 474, and the elbow pulley A 486 may be attached to the second link A 458, and the band, belt, or cable 488 may transmit motion between these two pulleys. This band mechanism may feature a fixed or variable transmission ratio, for example, a 1:1 ratio may be conveniently used. However, any other suitable mechanism may be used. Similarly, the second link B 462 may be coupled to the first link 456 via a revolute joint (elbow joint) 480 and driven by the T2 shaft 472 using a band mechanism 483. The end effector A 460 may be coupled to the second link A 458 via a revolute joint (wrist joint) 490, and the orientation of the end effector A 460 may be constrained by another band mechanism 492. The band mechanism may include an elbow pulley 494, a wrist pulley 496, and a band, belt, or cable 498. The elbow pulley 494 may connect to the first link, the wrist pulley 496 may connect to end effector A 460, and the band, belt, or cable 498 may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio.The variable transmission ratio may be achieved, for example, by using at least one pulley having a non-circular profile. By way of example, and referring to FIGS. 18A and 18B, a wrist pulley may feature a non-circular profile. An example of an arm using a non-circular pulley is disclosed in U.S. Patent Application No. 13 / 833,732, entitled "Robot Having Arm With Unequal Link Lengths," filed March 15, 2013, which is incorporated herein by reference in its entirety. Another example of an arm using a non-circular pulley is disclosed in U.S. Provisional Patent Application No. 62 / 132,066, entitled "2-Degree-of-Freedom 3-Link Robot Arm Mechanisms," filed March 12, 2015, which is incorporated herein by reference in its entirety. Another example of an arm using non-circular pulleys is disclosed in U.S. Provisional Patent Application No. 62 / 135,490, entitled "Arm Mechanisms with Two End Effectors," filed March 19, 2015, which is incorporated herein by reference in its entirety.

[0092] The variable transmission ratio may be selected to change the orientation of the end effector A 460 in a predefined manner as a function of the relative positions of the first link 456 and the second link A 458. For example, the variable transmission ratio may be selected to cause the end effector A 460 to follow a path to a station as shown in Figures 19A-19C.

[0093] Similarly, the end effector B 464 may be coupled to the second link B 462 via a revolute joint (wrist joint) 502, and the orientation of the end effector B 464 may be constrained by yet another band mechanism 504. The band mechanism 504 may include an elbow pulley 506, a wrist pulley 508, and a band, belt, or cable 510. The elbow pulley 506 may be connected to the first link 456, the wrist pulley 508 may be connected to the end effector B 464, and the band, belt, or cable 510 may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, by using at least one pulley having a non-circular profile. By way of example, and referring to FIG. 18A and FIG. 18B, the wrist pulley may feature a non-circular profile. The variable transmission ratio may be selected to change the orientation of the end effector B in a predefined manner as a function of the relative position of the first link B and the second link B. For example, the variable transmission ratio may be selected to cause the end effector B to follow a path to the station as shown in Figures 19A-19C.

[0094] A typical operation of this robot is shown in Figures 19-21. Figures 19A-19C show the robot 450 in a retracted position accessing the left station 530 with end effector A and the same station with end effector B. This allows the robot to perform a quick material change at the left station. Similarly, Figures 20A-20C show the robot 450 accessing station B 532 with end effectors A and B. This allows the robot to perform a quick material change at station B. Finally, Figures 21A-21C show that the robot may extend both end effectors 460, 464 to access the left station 530 and the right station 532 simultaneously. Additionally, the T1, T2, and T3 shafts may be rotated synchronously to reorient the arm mechanism to access another set of stations or any suitable combination of locations.

[0095] In the examples of Figures 17 to 21, a robot arm mechanism is shown with multiple elbow joints arranged coaxially. However, as shown diagrammatically in the example robot 450' of Figure 22, the elbow joints may be arranged in an offset state 540 as two separate joints 542, 544. Yet another example embodiment is shown diagrammatically in Figures 23A and 23B. Figure 23A shows a robot 600 with a drive 602, a common upper arm 604, a forearm A 606, and a forearm B 608. The forearms A 606 and B 608 share a common elbow 610. Here, the robot 600 includes an end effector mounted at the wrist joint on the upper surface of the forearm 608, and an end effector mounted at the wrist joint on the upper surface of the forearm 606. The robot 600 may be driven and utilized in a similar manner to the robot 450. 23B shows a robot 600' comprising a drive 602, a common upper arm 604, a forearm A 606' and a forearm B 608. Forearm A 606' and forearm B 608 have a common elbow 610. Here, the robot 600' comprises an end effector mounted at the wrist joint on the upper surface of the forearm 608 and an end effector mounted at the wrist joint on the lower surface of the forearm 606'. This robot 600' may be driven and utilized in a similar manner as robot 450.

[0096] FIG. 24 shows a side view of a robot with a robot arm mechanism 702 according to an embodiment attached to a robot drive 704. The arm mechanism may be comprised of a linkage A 706 and a linkage B 708. An exemplary internal mechanism of the robot 700 of FIG. 24 is shown diagrammatically in FIG. 25A and FIG. 25B. The arm mechanism may be driven by a three-axis spindle 704 with three coaxial shafts, for example, an outer T1 shaft 710, a T2 shaft 712, and an inner T3 shaft 714. The T2 shaft 712 may be partially inside the outer T1 shaft 710, and the inner T3 shaft 714 may be partially inside the T2 shaft 712. Linkage A 706 may be comprised of a first link (upper arm) 716, a second link (forearm) 718, and a third link (end effector A) 720. The first link may be directly attached to the T3 shaft 714. The second link may be coupled to the first link via a revolute joint 722 and constrained by the T2 shaft 712 with a band mechanism 724. The band mechanism 724 may comprise a shoulder pulley, an elbow pulley, and a band, belt, or cable. The shoulder pulley may be attached to the T2 shaft 712, the elbow pulley may be attached to the second link 718, and the band, belt, or cable may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio; however, any other suitable mechanism may be used. The third link 720 of linkage A may be coupled to the second link 718 via a revolute joint 726, and the orientation of the third link 720 may be constrained by another band mechanism 728. The band mechanism 728 may comprise a right elbow pulley, a wrist pulley, and a band, belt, or cable. The right elbow pulley may be connected to a first link 716, the wrist pulley may be connected to a third link 720, and a band, belt, or cable may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, by using at least one pulley having a non-circular profile. By way of example, and referring to Figures 25A and 25B, the wrist pulley may feature a non-circular profile.The variable transmission ratio may be selected to change the orientation of the third link (end effector A) of linkage A in a predefined manner as a function of the relative position of the first link and the second link. The relative position of the first link and the second link may be conveniently expressed as an indentation angle between the two links. As an example, the transmission ratio of the two band mechanisms of linkage A 706 may be selected such that, when the first link is driven by the T3 shaft and the T2 shaft remains stationary, a reference point on the third link (usually the nominal center of end effector A) follows a predefined path, keeping the orientation of the third right link (end effector A) predefined (e.g., constant).

[0097] As an example, a path may be selected as an access path to any of the stations of FIG. 16, as shown in FIG. 26A-26C. Referring again to FIG. 25A and FIG. 25B, linkage B 708 may be composed of a first link (upper arm) 732, a second link 734 (forearm), and a third left link (end effector B) 736. The first link 732 may be attached directly to the T1 shaft 710. The second link 734 may be coupled to the first link 732 via a revolute joint 738 and constrained by the T2 shaft 712 using a band mechanism 740. This band mechanism may comprise another shoulder pulley, an elbow pulley, and a band, belt, or cable. The other shoulder pulley may be attached to the T2 shaft 712, and the elbow pulley may be attached to the second link 734, and the band, belt, or cable may transmit motion between these two pulleys. Similar to the right linkage A, the band mechanism may feature a variable transmission ratio. However, any other suitable mechanism may be used. The remaining components of linkage B may be configured similarly to linkage A, and the operation of linkage B is substantially similar to that of linkage A, except that the T1 shaft 710 takes on the role of the T3 shaft 714.

[0098] A typical operation of this robot is shown in Figures 26-28. Figures 26A-26C show the robot 700 in a retracted position accessing the left station 532 with end effector A 720 and the same station with end effector B 736. This allows the robot 700 to perform a quick material change at the left station 532. Similarly, Figures 27A-27C show the robot 700 accessing station 534 with end effectors A 720 and B 736. This allows the robot to perform a quick material change at station 534. Additionally, Figures 28A-28C show that the robot may extend both end effectors to access the left and right stations simultaneously. Additionally, the T1, T2, and T3 shafts may be rotated synchronously to reorient the arm mechanism to access another set of stations or any suitable location.

[0099] Alternatively, as shown in Figures 29A and 29B, the arm mechanism may be driven by a four-axis spindle 750 with four coaxial shafts, for example an outer T1 shaft 752, a T2 shaft 754, a T3 shaft 756, and an inner T4 shaft 758 as shown in the example of Figure 29. In this particular example, the T1 shaft 752 may connect to a first link 760 of linkage A, the T2 shaft 754 may drive a second link 762 of linkage A, the T3 shaft 756 may drive a second link 764 of linkage B, and the T4 shaft 758 may connect to a first link 766 of linkage B. However, any suitable configuration of four shafts may be used.

[0100] Yet another exemplary embodiment is shown diagrammatically in Figures 30A and 30B. Figure 30A shows a robot 780 with a drive 782 and arms A 784 and B 786 nested as shown. The robot 780 has similar features as robots 700, 750, etc. and may be driven in a similar manner. Here, the robot 780 has an end effector mounted at the wrist joint on the upper surface of one forearm and an end effector mounted at the wrist joint on the upper surface of the other forearm. The robot 780 may be driven and utilized in a similar manner as the other robots. Figure 30B shows a robot 780' with a drive 782 and arms A 784' and B 786 nested as shown. The robot 780' has similar features as robots 700, 750, etc. and may be driven in a similar manner. Here, the robot 780' has an end effector mounted at the wrist joint on the upper surface of one forearm and an end effector mounted at the wrist joint on the lower surface of the other forearm. This robot 780' may be driven and utilized in a manner similar to other robots.

[0101] The disclosed embodiments are similarly applicable to dual end effector robot arm mechanisms that may be used for material transfer to and from parallel (laterally offset) stations in a semiconductor wafer processing tool. An exemplary layout of a semiconductor wafer processing tool 810 is shown generally in a top view in FIG. 31. In this particular example, the tool features four parallel stations, e.g., a set of load locks 812 and three sets of process module stations 814 coupled to a transfer chamber 816.

[0102] As shown in the example of FIG. 31, the arm mechanism may access each station in the tool along a predefined path, e.g., substantially straight paths 818, 820, with a predefined end effector orientation, e.g., along the straight paths 818, 820.

[0103] FIG. 32 shows a side view of a robot 850 with an exemplary robot arm mechanism 852 according to an embodiment attached to a robot drive 854. The arm mechanism may be composed of a first link (upper arm) 856, a second link (forearm) A 858, an end effector A 860, a second link (forearm) B 862, and an end effector B 864. An exemplary internal mechanism of the robot 850 of FIG. 32 is shown diagrammatically in FIG. 33A and FIG. 33B. The arm mechanism may be driven by a three-axis spindle 854 with three coaxial shafts, e.g., an outer T1 shaft 870, a T2 shaft 872, and an inner T3 shaft 874. The first link 856 of the robot arm mechanism may be directly attached to the T1 shaft 870. The second link A 858 may be coupled to the first link 856 via a revolute joint (elbow joint) 880 and driven by the T3 shaft 874 using a band mechanism 882. The band mechanism 882 may comprise a shoulder pulley A 884, an elbow pulley A 886, and a band, belt, or cable 888. The shoulder pulley A 884 may be attached to the T3 shaft 874, and the elbow pulley A 886 may be attached to the second link A 858, and the band, belt, or cable 888 may transmit motion between these two pulleys. This band mechanism may feature a fixed or variable transmission ratio, for example, a 1:1 ratio may be conveniently used. However, any other suitable mechanism may be used. Similarly, the second link B 862 may be coupled to the first link 856 via a revolute joint (elbow joint) 880 and driven by the T2 shaft 872 using the band mechanism 883. The end effector A 860 may be coupled to the second link A 858 via a support structure 861 and a revolute joint (wrist joint) 890. 32, the support structure 861 may be attached to the revolute joint 890 below the second link A 858 and may be shaped to avoid mechanical interference with, for example, second link A 858 and second link B 862 during operation. The support structure 861 may be formed by one or more components integrated with the end effector A 860 or the revolute joint 890, or implemented in any other suitable manner.The orientation of the end effector A 860 may be constrained by a band mechanism 892. The band mechanism may include an elbow pulley 894, a wrist pulley 896, and a band, belt, or cable 898. The elbow pulley 894 may be connected to a first link, the wrist pulley 896 may be connected to a support structure 861 that includes the end effector A 860, and the band, belt, or cable 898 may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, by using at least one pulley having a non-circular profile. By way of example, and referring to FIG. 33A and FIG. 33B, the wrist pulley may feature a non-circular profile. An example of an arm using non-circular pulleys is disclosed in U.S. Patent Application No. 13 / 833,732, entitled "Robot Having Arm With Unequal Link Lengths," filed March 15, 2013, which is incorporated herein by reference in its entirety. Another example of an arm using non-circular pulleys is disclosed in U.S. Provisional Patent Application No. 62 / 132,066, entitled "2-Degree-of-Freedom 3-Link Robot Arm Mechanisms," filed March 12, 2015, which is incorporated herein by reference in its entirety. Another example of an arm using non-circular pulleys is disclosed in U.S. Provisional Patent Application No. 62 / 135,490, entitled "Arm Mechanisms with Two End Effectors," filed March 19, 2015. Another example of an arm using a non-circular pulley is disclosed in U.S. Provisional Patent Application No. 62 / 137,458, entitled "Robot Arm Mechanisms with Two End Effectors," filed March 24, 2015, which is incorporated herein by reference in its entirety.

[0104] The variable transmission ratio may be selected to change the orientation of the end effector A 860 in a predefined manner as a function of the relative positions of the first link 856 and the second link A 858. For example, the variable transmission ratio may be selected to make the end effector A 860 follow a path to a station as shown in FIG. 34A-34C. The end effector B 864 may be coupled to the second link B 862 via a revolute joint (wrist joint) 902, and the orientation of the end effector B 864 may be constrained by yet another band mechanism 904. The band mechanism 904 may comprise an elbow pulley 906, a wrist pulley 908, and a band, belt, or cable 910. The elbow pulley 906 may connect to the first link 856, the wrist pulley 908 may connect to the end effector B 864, and the band, belt, or cable 910 may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, by using at least one pulley having a non-circular profile. By way of example, and with reference to Figures 33A and 33B, a wrist pulley may feature a non-circular profile.

[0105] The variable transmission ratio may be selected to change the orientation of the end effector B in a predefined manner as a function of the relative position of the first link and the second link B. For example, the variable transmission ratio may be selected so that the end effector B follows a path to the station as shown in Figs. 34A to 34C. A typical operation of the robot is shown in Figs. 34 and 35. Figs. 34A to 34C show the robot 850 in a retracted position in front of the left station 530, accessing the left station 530 with the end effector A and accessing the same station with the end effector B. This allows the robot to perform a quick material exchange at the left station. Still referring to Figs. 34A to 34C, the end effector A 860 may be extended to the left station 530 along a desired path, for example a substantially straight path 820. This is done by rotating the T3 shaft 874 clockwise and coordinating the rotation of the T1 shaft 870 with the rotation of the T3 shaft 874 so that the end effector A 860 follows the desired linear path 820. At the same time, the T2 shaft 872 may be rotated synchronously with the T1 shaft 870 so that the end effector B 864 remains folded on the second link B 862. Similarly, the end effector A 860 may be retracted from the left station 530 along the desired path, e.g., the same substantially linear path 820. This is done by rotating the T3 shaft 874 counterclockwise and coordinating the rotation of the T1 shaft 870 with the rotation of the T3 shaft 874 so that the end effector A 860 follows the desired linear path 820. Again, the T2 shaft 872 may be rotated synchronously with the T1 shaft 870 to keep the end effector B 864 folded on the second link B 862. The end effector B 864 may then be extended along a desired path, such as a substantially straight path 820, to the left station 530. This is done by rotating the T2 shaft 872 clockwise, coordinating the rotation of the T1 shaft 870 with the rotation of the T2 shaft 872 so that the end effector B 864 follows the desired straight path 820.At the same time, the T3 shaft 874 may be rotated in synchronism with the T1 shaft 870 to keep the end effector A 860 folded on the second link A 858. Additionally, the end effector B 864 may be retracted from the left station 530 along a desired path, e.g., the same substantially straight path 820. This is done by rotating the T2 shaft 872 counterclockwise and coordinating the rotation of the T1 shaft 870 with the rotation of the T2 shaft 872 so that the end effector B 864 follows the desired straight path 820. Again, the T3 shaft 874 may be rotated in synchronism with the T1 shaft 870 to keep the end effector A 860 folded on the second link A 858. Additionally, the T1, T2, and T3 shafts may be rotated in synchronism to reorient the arm mechanism to access a different location, e.g., the right station 532.

[0106] 35A-35C show the robot 850 accessing the right station 532 with end effectors A and B. This allows the robot to perform a quick material change at the right station 532. In FIG. 35A-35C, the end effector A 860 may be extended to the right station 532 along a desired path, e.g., a substantially straight path 818. This is done by rotating the T3 shaft 874 counterclockwise and coordinating the rotation of the T1 shaft 870 with the rotation of the T3 shaft 874 so that the end effector A 860 follows the desired straight path 818. At the same time, the T2 shaft 872 may be rotated synchronously with the T1 shaft 870 so that the end effector B 864 remains folded on the second link B 862. Similarly, the end effector A 860 may be retracted from the right station 532 along the same desired path, e.g., a substantially straight path 818. This is done by rotating the T3 shaft 874 clockwise, and coordinating the rotation of the T1 shaft 870 with the rotation of the T3 shaft 874, such that end effector A 860 follows the desired linear path 818. Again, the T2 shaft 872 may be rotated synchronously with the T1 shaft 870, such that end effector B 864 remains folded on the second link B 862. End effector B 864 may then be extended along the desired path, e.g., the substantially linear path 818, to the right station 532. This is done by rotating the T2 shaft 872 counterclockwise, and coordinating the rotation of the T1 shaft 870 with the rotation of the T2 shaft 872, such that end effector B 864 follows the desired linear path 818. At the same time, the T3 shaft 874 may be rotated synchronously with the T1 shaft 870 to cause end effector A 860 to remain folded on the second link A 858. Additionally, end effector B 864 may be retracted from the right station 532 along a desired path, e.g., a substantially straight path 818. This is done by rotating the T2 shaft 872 clockwise, coordinating the rotation of the T1 shaft 870 with the rotation of the T2 shaft 872 such that end effector B 864 follows the desired straight path 818.Again, the T3 shaft 874 may be rotated synchronously with the T1 shaft 870 to keep the end effector A860 folded on the second link A858.

[0107] 34 and 35 are examples, and the arm mechanism may perform other desired actions and suitable motions. For example, the rotations of some or all of shafts 870, 872, and 874 may be defined and coordinated to minimize the amount of motion of a retracted end effector, e.g., end effector A 860, during the extension and retraction of another end effector, e.g., end effector B 864. As another example, individual movements such as extension, retraction, and rotation may be blended and / or overlapped to achieve a smooth motion path and reduce the overall duration of the motion.

[0108] The examples of Figures 32 and 33 show a robotic arm mechanism in which a support structure 861 is attached to the revolute joint 890 below the second link A 858. However, the support structure 861 may also be attached to the revolute joint 890 above the second link A 858 as shown diagrammatically in Figure 36. Exemplary internal workings of the exemplary embodiment of Figure 36 are shown diagrammatically in Figures 37A and 37B. Alternatively, the support structure 861 may be attached to the revolute joint 90 in any suitable manner and may have any suitable shape.

[0109] The examples of Figures 32-37 show a robotic arm mechanism with second link A 858 and second link B 862 of the same length, although the overall length and joint-to-joint length of second link A 858 and second link B 862 may be any suitable length. Similarly, although end effector A 860 and end effector B 864 are shown as the same length in the examples of Figures 32-37, these end effectors may be any suitable length.

[0110] 32-37 include band mechanisms 882 and 883, any other suitable single or multi-stage transmission mechanisms having a fixed or variable transmission ratio may be used, including, but not limited to, chains and gears. Similarly, any other suitable single or multi-stage transmission mechanisms having a suitable variable transmission ratio, such as chains or gears, may be employed in place of band mechanisms 892 and 904. Additionally, chains as well as gears may be used (e.g., in place of or in combination with bands, belts, or cables) in any of the embodiments disclosed herein.

[0111] In one example of a suitable mechanism, shown in Figures 36 and 37, a robot 850' includes an end effector 860' with a bridge that is attached to the superior side of the wrist joint, rather than the inferior side of the wrist joint as shown in Figure 32. In another example of a suitable mechanism, shown in Figures 38A and 38B, a robot 850'' includes offset shoulder joints 897, 899.

[0112] An exemplary arrangement of a semiconductor wafer processing tool 1010 is shown diagrammatically in a top view in FIG. 39. In this example, the tool features four parallel stations 1012, e.g., one load lock and three process module stations 1012 coupled to a transport chamber 1014. FIG. 40 shows a side view of a robot 1050 with an exemplary two degree of freedom three-link robot arm mechanism 1054 attached to a robot drive 1056. The arm mechanism 1054 may be comprised of a first link (upper arm) 1058, a second link (forearm) 1060, and a third link (end effector) 1062. An exemplary internal mechanism of the robot 1050 of FIG. 40 is shown diagrammatically in FIG. 41A and FIG. 41B. The arm mechanism may be driven by a two-axis spindle 1064 with two coaxial shafts, e.g., an outer T1 shaft 1066 and an inner T2 shaft 1068. As shown in FIGS. 41A and 41B, the orientation of the end effector 1062 may be constrained by a band mechanism 1068. The band mechanism 1068 may include an elbow pulley 1070, a wrist pulley 1072, and a band, belt, or cable. The elbow pulley 1070 may connect to the first link 1058, the wrist pulley 1072 may connect to the end effector 1062, and the band, belt, or cable may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, with at least one pulley having a non-circular profile. By way of example, referring to FIGS. 41A and 41B, the wrist pulley 1072 may feature a non-circular profile and the elbow pulley 1070 may have a substantially circular profile. The variable transmission ratio may be selected to change the orientation of the end effector in a predefined manner as a function of the relative positions of the first and second links. For example, the variable transmission ratio may be selected to cause the end effector to follow a path to the station as shown in FIG.

[0113] An exemplary mechanism with variable transmission ratio that provides the functionality as described above will now be described. For example, see Fig. 42A to Fig. 45. The appropriate geometry of the arm mechanism, i.e., inter-articular link length and end effector length, may be conveniently determined from the station locations, the required reach of the end effector, and constraints or obstacles in the workspace (which may determine the allowable turning radius of the arm mechanism in the retracted position).

[0114] An exemplary length of the third link 1062 may be determined as follows. The length of the third link, i.e., L3, may be conveniently defined as the distance between the axis of rotation of the wrist joint 1080 and a reference point 1082 on the third link (usually the nominal center of the end effector). As the end effector extends to the station, there are effectively three constraints: 1) the location of the reference point on the third link (usually the nominal center of the end effector) must be substantially aligned with the location of the station; 2) the end effector must be in the desired orientation, e.g., pointing in a straight line along the access path to the station; and 3) the wrist joint must be retracted far enough to avoid colliding with obstacles on the path to the station. The above constraints may be used to determine the length of the third link (end effector), e.g., as a minimum value subject to the constraints. By way of example, the following equation may be used:

[0115] TIFF2024178225000002.tif1168

[0116] where X stn and Y stn are the x-axis and y-axis offsets of the station location in the robot-centered Cartesian coordinate system (i.e., the robot center (shoulder joint) is (0,0)), and R s is the allowable turning radius R that defines the circular space in which the retracted robot arm mechanism can freely rotate. s It is.

[0117] An exemplary length of the second link can be determined as follows: The inter-articular length of the second link, i.e., L2, may be defined as the distance between the axis of rotation of the elbow joint and the axis of rotation of the wrist joint. For semiconductor wafer processing tools with multiple sets of parallel stations, such as the exemplary arrangement of FIG. 39, the length of the forearm may be conveniently selected to be equal to, or longer if necessary than, the offset of the station locations from the axis of symmetry of the parallel stations, i.e., half the distance between the station locations.

[0118] TIFF2024178225000003.tif944

[0119] For the end effector of the arm mechanism to achieve the required station extension without overextending the elbow joint, L2 must be set to X. stn It may need to be larger.

[0120] An exemplary length of the first link may be determined as follows: The inter-articular length of the first link, or L1, may be defined as the distance between the axis of rotation of the shoulder joint and the axis of rotation of the elbow joint. Given values ​​for L2 and L3, the length of the first link may be determined such that, for example, the arm mechanism is within an allowable swing radius when retracted.

[0121] TIFF2024178225000004.tif975

[0122] Here, R w is the radius of a circular payload, such as a wafer, carried by the end effector.

[0123] For example, x-axis offset X stn 388.6mm, y-axis offset Y stn The station location may be selected with a radius of rotation R that defines the circular space in which the retracted robot arm mechanism can freely rotate. smay be selected as, for example, 605.8 mm. The payload carried by the arm mechanism may be, for example, of radius R w Based on the above exemplary guidelines, a suitable exemplary arm mechanism geometry, i.e., inter-articular link length and end effector length, may be L3=565.5 mm, L2=397.6 mm>X stn = 388.6 mm, and L1 = 287.9 ​​mm.

[0124] Consider the exemplary arm mechanism shown in Figures 40 and 41, in which the orientation of the end effector may be constrained, for example, by a band mechanism with a circular elbow pulley and a non-circular wrist pulley. Given the exemplary station locations and arm mechanism geometry discussed above, the wrist pulley may have a profile shown by line 1102 in Figure 42A (for clarity, only half of the profile is shown in this figure). The relative orientation of the wrist pulley to the third link (end effector) is shown by solid arrow 1104. Arrow 1104 points from the axis (center) of the wrist joint along the longitudinal axis of the third link to the center of the end effector. For comparison, a circular elbow is shown by line 1106.

[0125] 42B to 42E show how the orientation of the end effector 1062 of the exemplary arm mechanism described above, having a wrist pulley geometry defined according to FIG. 42A, is constrained as a function of the relative angle of the second link 1060 with respect to the first link 1058 (i.e., the relative angle between the first link and the second link).

[0126] 43 shows pulley profiles that may be used with the same arm geometry as the previous pulley profile examples and would result in the same or similar motion, where the end effector orientation 1120 is shown with a black arrow and the elbow pulley profile 1124 and wrist pulley profile 1122 are shown as non-circular.

[0127] A band, belt, or cable mechanism may be provided to constrain the orientation of the end effector with two non-circular pulleys. For example, this mechanism may be applied to both single end effector configurations (such as Figs. 42A-42E) and two end effector configurations (such as Figs. 32 and 36), in which case substantially the same kinematics may be applied to all. In this additional example, the elbow pulley connected to the upper arm is non-circular and the wrist pulley connected to the end effector is also non-circular. This may be provided as an alternative to the pulley profile example for the special case where the elbow pulley is circular and the wrist pulley is non-circular. As an example, the profiles of each pulley are shown in Fig. 43. As in Fig. 42A, only half of each non-circular pulley is shown. Here, each profile was generated for the same arm geometry (link length) as the non-circular pulley example above.

[0128] An example of the stepwise motion of the robot arm mechanism as the end effector of the robot arm mechanism extends along a linear path to the example stations described above is shown in Figure 44. To cause the end effector of the robot arm mechanism to perform the example motion of Figure 44, the shafts of the robot drive may be driven as shown in graph 1150 of Figure 45. Graph 1150 shows T1 shaft position 1152 over time and T2 shaft position 1154 over time.

[0129] Figure 46 shows another example of the stepwise motion of a robot arm mechanism as the end effector extends to the same example station along a path formed by two segments 1200, 1202 that merge, this time around a common way-point 1204. To achieve the example motion of Figure 46, the shafts of the robot drive may be rotated as shown in graph 1250 of Figure 47. Graph 1250 shows T1 shaft position 1252 over time and T2 shaft position 1254 over time.

[0130] 45 and 47, the zero point of the angle of the shaft of the robot drive unit is defined as follows: When the arm mechanism is in the folded position (retracted position) and the third link (end effector) is along the x-axis (i.e., pointing in the 3 o'clock direction), the angle of the T1 shaft is 0 degrees and the angle of the T2 shaft is 180 degrees. At this time, the angle of the first link is 0 degrees, the angle of the second link is 180 degrees, and the angle of the third link (end effector) is 0 degrees.

[0131] 48 shows a side view of a robot 1300 with an exemplary robot arm mechanism 1310 with two end effectors attached to a robot drive 1312. The arm mechanism may be composed of a first link 1314 (upper arm), a second link 1316 (forearm) A, a third link 1318 (end effector) A, a second link 1320 (forearm) B, and a third link 1322 (end effector) B.

[0132] An exemplary internal mechanism of the robot of FIG. 48 is shown diagrammatically in FIG. 49A and FIG. 49B. The arm mechanism may be driven by a three-axis spindle with three coaxial shafts, for example, an outer T1 shaft 1340, a T2 shaft 1342, and an inner T3 shaft 1344. In some embodiments, the T2 shaft 1342 may be partially inside the outer T1 shaft 1340, and the inner T3 shaft 1344 may be partially inside the T2 shaft 1342. The orientation of the end effector A may be constrained by a band mechanism. The band mechanism may include an elbow pulley, a wrist pulley, and a band, belt, or cable. The elbow pulley may be connected to the first link, the wrist pulley may be connected to a support structure with the end effector A, and the band, belt, or cable may transmit motion between these two pulleys. The band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, by using at least one pulley with a non-circular profile. By way of example, with reference to FIG. 49, the wrist pulley may feature a non-circular profile and the elbow pulley may have a substantially circular profile. Similarly, the orientation of the end effector B may be constrained by another band mechanism. This band mechanism may comprise an elbow pulley, a wrist pulley, and a band, belt, or cable. The elbow pulley may be connected to a first link, the wrist pulley may be connected to the end effector B, and the band, belt, or cable may transmit motion between these two pulleys. Again, the band mechanism may feature a variable transmission ratio. The variable transmission ratio may be achieved, for example, by using at least one pulley having a non-circular profile. By way of example, with reference to FIG. 49A and FIG. 49B, the wrist pulley may feature a non-circular profile and the elbow pulley may have a substantially circular profile. The variable transmission ratio may be selected to change the orientation of each of the two end effectors in a predefined manner as a function of the relative position of the first link and the corresponding second link. For example, a variable transmission ratio may be selected so that the end effector follows a path to the station as shown in Figure 39. An example is shown below.

[0133] The appropriate geometry, i.e., inter-articular link lengths and end effector lengths, of the arm mechanisms of FIGS. 48 and 49 may be determined based on the same guidelines set forth above for the exemplary 2-DOF 3-link robot arm mechanism of FIG. 40.

[0134] Similarly, consider the exemplary arm mechanism shown in Figures 40 and 41, in which the orientation of the end effector may be constrained by, for example, a band mechanism with a circular elbow pulley and a non-circular wrist pulley. Given the exemplary station locations selected above and the geometry of the arm mechanism (X stn =388.6mm, Y stn = 1,030.2 mm, L1 = 287.9 ​​mm, L2A = L2B = L2 = 397.6 mm, and L3A = L3B = L3 = 565.5 mm), the same geometry previously described with respect to FIG. 40 may be used for the two wrist pulleys.

[0135] 50 illustrates an example of a stepwise motion of a robotic arm mechanism as end effector A extends along a linear path 1440 to the aforementioned example station. In this particular example, end effector B and second link B remain folded over the first link to remain within the allowable turning radius of the robotic arm mechanism. To cause the robotic arm mechanism to perform the example motion of FIG. 50, the shafts of the robotic drive may be driven according to the example motion profile shown in graph 1490 of FIG. 51. Graph 1490 illustrates T1 shaft position 1492 over time, T2 shaft position 1494 over time, and T3 shaft position 1496 over time.

[0136] 52 illustrates another example of the stepwise motion of a robot arm mechanism as end effector A extends to the same example station along a path formed by two segments 1540, 1542 that merge, this time around a common way point 1544. In this example, the motion of the second link B, and therefore end effector B, is controlled to limit the range of motion of the payload carried on end effector B. To achieve the example motion of FIG. 52, the shafts of the robot drive may be rotated as shown in graph 1640 of FIG. 53. Graph 1640 illustrates T1 shaft position 1642 over time, T2 shaft position 1644 over time, and T3 shaft position 1646 over time.

[0137] 51 and 53, the zero point of the angle of the shaft of the robot drive unit is defined as follows: When the arm mechanism is in the folded position (retracted position) and the third links (end effectors) A and B are along the x-axis (i.e., pointing in the 3 o'clock direction), the angle of the T1 shaft is 0 degrees, and the angles of the T2 shaft and the T3 shaft are 180 degrees. At this time, the angle of the first link is 0 degrees, the angle of the second links A and B is 180 degrees, and the angle of the third links (end effectors) A and B is 0 degrees.

[0138] In one aspect, the apparatus includes a drive and a robotic arm. The drive includes a first drive shaft rotatable about a first axis of rotation and a second drive shaft rotatable about a second axis of rotation, the second drive shaft being coaxial with the first drive shaft, partially internal to the first drive shaft, and axially rotatable within the first drive shaft. The robotic arm includes an upper arm connected to the drive at the first drive shaft, a forearm coupled to the upper arm, and an end effector coupled to the forearm, the forearm coupled to the upper arm at a first revolute joint and rotatable about the first revolute joint, the first revolute joint being drivable by a first band mechanism coupled to the second drive shaft, the end effector coupled to the forearm at a second revolute joint and rotatable about the second revolute joint, the second revolute joint being drivable by a second band mechanism coupled to the first revolute joint. The second band mechanism is configured to provide a variable transmission ratio.

[0139] In another aspect, the first band mechanism includes a shoulder pulley attached to the second drive shaft, a first elbow pulley coupled to the forearm, and a band, belt, or cable disposed between the shoulder pulley and the first elbow pulley to transfer motion between the shoulder pulley and the first elbow pulley.

[0140] In another aspect, the second band mechanism includes a second elbow pulley coupled to the upper arm, a wrist pulley coupled to the end effector, and a band, belt, or cable disposed between the second elbow pulley and the wrist pulley to transfer motion between the second elbow pulley and the wrist pulley.

[0141] In another aspect, at least one of the second elbow pulley and the wrist pulley has a non-circular profile to provide the variable transmission ratio.

[0142] In another aspect, the variable transmission ratio is selected to change the orientation of the end effector in a predefined manner as a function of the relative position of the upper arm and the forearm.

[0143] In another aspect, one or more of the first drive shaft and the second drive shaft are axially movable to facilitate vertical movement of the robotic arm.

[0144] In another aspect, an apparatus includes a drive and a robotic arm, the drive including a first drive shaft rotatable about a first axis of rotation, a second drive shaft rotatable about a second axis of rotation, and a third drive shaft rotatable about a third axis of rotation, the second drive shaft being coaxial with, partially within, and axially rotatable within the first drive shaft, and the third drive shaft being coaxial with, partially within, and axially rotatable within the second drive shaft. The robot arm comprises an upper arm connected to the drive device at the first drive shaft, a forearm coupled to the upper arm, and a first end effector and a second end effector coupled to the forearm, the forearm being coupled to the upper arm at a first rotary joint and rotatable about the first rotary joint, the first rotary joint being drivable by a single stage band mechanism, the single stage band mechanism comprising a first shoulder pulley drivable by the third drive shaft, a first elbow pulley partially forming the first rotary joint, and a band, belt, or cable configured to transfer motion between the first shoulder pulley and the first elbow pulley, the first end effector and the second end effector being coupled to the forearm at a second rotary joint, and orientations of the first end effector and the second end effector being controlled via a two stage band mechanism. The first stage of the two-stage band mechanism includes a second shoulder pulley drivable by the second drive shaft, a second elbow pulley forming in part the first revolute joint, and an upper band, belt or cable configured to transfer motion between the second shoulder pulley and the second elbow pulley.The second stage of the two stage band mechanism includes a third elbow pulley coupled to the second elbow pulley, a first wrist pulley coupled to the first end effector, and a first lower band, belt, or cable configured to transfer motion between the third elbow pulley and the first wrist pulley, and the second stage of the two stage band mechanism further includes a fourth elbow pulley coupled to the second elbow pulley, a second wrist pulley coupled to the second end effector, and a second lower band, belt, or cable configured to transfer motion between the fourth elbow pulley and the second wrist pulley. At least one of the motion between the first shoulder pulley and the first elbow pulley, the motion between the second shoulder pulley and the second elbow pulley, the motion between the third elbow pulley and the first wrist pulley, and the motion between the fourth elbow pulley and the second wrist pulley is performed with a variable transmission ratio.

[0145] In another aspect, at least one of the third elbow pulley and the first wrist pulley has a non-circular profile to provide the variable transmission ratio to the two-stage band mechanism.

[0146] In another aspect, at least one of the fourth elbow pulley and the second wrist pulley has a non-circular profile to provide the variable transmission ratio to the two-stage band mechanism.

[0147] In another embodiment, at least one of the first lower band, belt, or cable and the second lower band, belt, or cable are configured in a cross-like configuration.

[0148] In another aspect, the variable transmission ratio is selected to change the orientation of the first end effector and the second end effector in a predefined manner as a function of the relative positions of the upper arm, the forearm, and the second drive shaft.

[0149] In another aspect, the first rotating joint is either to the right of an imaginary line extending from the first shoulder pulley to the first wrist pulley or to the left of an imaginary line extending from the first shoulder pulley to the first wrist pulley.

[0150] In another aspect, an apparatus includes a drive, a first robotic arm, and a second robotic arm, the drive including a first drive shaft rotatable about a first axis of rotation, a second drive shaft rotatable about a second axis of rotation, and a third drive shaft rotatable about a third axis of rotation, the second drive shaft being coaxial with, partially within, and axially rotatable within the first drive shaft, and the third drive shaft being coaxial with, partially within, and axially rotatable within the second drive shaft. The first robot arm comprises a first upper arm connected to the drive device at the first drive shaft, a first forearm coupled to the first upper arm, and a first end effector coupled to the first forearm, wherein the first forearm is coupled to the first upper arm at a first rotary joint, the first rotary joint being drivable by the second drive shaft using a first band mechanism, and the first end effector is coupled to the first forearm at a third rotary joint, the third rotary joint being drivable by the first rotary joint using a third band mechanism. The second robot arm includes a second upper arm connected to the drive device at the third drive shaft, a second forearm coupled to the second upper arm, and a second end effector coupled to the second forearm, the second forearm coupled to the second upper arm at a second rotary joint, the second rotary joint being drivable by the second drive shaft using a second band mechanism, the second end effector coupled to the second forearm at a fourth rotary joint, the fourth rotary joint being drivable by the second rotary joint using a fourth band mechanism, and at least one of the first band mechanism, the second band mechanism, the third band mechanism, and the fourth band mechanism has a variable transmission ratio.

[0151] In another aspect, the first band mechanism includes a first shoulder pulley attached to the first drive shaft, a first elbow pulley attached to the first forearm, and a first band, belt, or cable configured to transfer motion between the first shoulder pulley and the first elbow pulley.

[0152] In another aspect, at least one of the first shoulder pulley and the first elbow pulley has a non-circular profile to provide the variable transmission ratio to the first band mechanism.

[0153] In another aspect, the third band mechanism includes a second elbow pulley operable with the first elbow pulley, a first wrist pulley coupled to the first end effector, and a third band, belt, or cable configured to transfer motion between the second elbow pulley and the first wrist pulley.

[0154] In another aspect, at least one of the second elbow pulley and the first wrist pulley has a non-circular profile to provide the variable transmission ratio to the third band mechanism.

[0155] In another aspect, the second band mechanism includes a second shoulder pulley attached to the third drive shaft, a third elbow pulley attached to the second forearm, and a second band, belt, or cable configured to transfer motion between the second shoulder pulley and the third elbow pulley.

[0156] In another aspect, at least one of the second shoulder pulley and the third elbow pulley has a non-circular profile to provide the variable transmission ratio to the second band mechanism.

[0157] In another aspect, the fourth band mechanism includes a fourth elbow pulley operable with the third elbow pulley, a second wrist pulley coupled to the second end effector, and a fourth band, belt, or cable configured to transfer motion between the fourth elbow pulley and the second wrist pulley.

[0158] In another aspect, at least one of the fourth elbow pulley and the second wrist pulley has a non-circular profile to provide the variable transmission ratio to the fourth band mechanism.

[0159] In another aspect, the variable transmission ratio is selected to change an orientation of the first end effector in a predefined manner as a function of a relative position of the first upper arm and the first forearm.

[0160] In another aspect, a transmission ratio of the first band mechanism and a transmission ratio of the third band mechanism are selected such that when the first upper arm is driven by the first drive shaft and the second drive shaft is stationary, a center point of the first end effector follows a predefined path while maintaining a predefined orientation of the first end effector.

[0161] In another aspect, the variable transmission ratio is selected to change an orientation of the second end effector in a predefined manner as a function of a relative position of the second upper arm and the second forearm.

[0162] In another aspect, the transmission ratio of the second band mechanism and the transmission ratio of the fourth band mechanism are selected such that when the second upper arm is driven by the third drive shaft and the second drive shaft is stationary, a center point of the second end effector follows a predefined path while maintaining a predefined orientation of the second end effector.

[0163] It should also be noted that the above description is merely illustrative. Various variations and modifications may occur to those skilled in the art. For example, the features of the various dependent claims may be combined with each other in any suitable combination. In addition, features from the various embodiments described above may be selectively combined to form new embodiments. This specification is therefore intended to embrace all such variations, modifications, and variations that fall within the scope of the appended claims.

Claims

[Claim 1] A drive unit; A robot arm, the drive device comprises a first drive shaft rotatable about a first axis of rotation and a second drive shaft rotatable about a second axis of rotation, the second drive shaft being coaxial with the first drive shaft, partially inside the first drive shaft and axially rotatable within the first drive shaft; The robot arm includes: an upper arm connected to the drive device at the first drive shaft; a forearm coupled to the upper arm; an end effector coupled to the forearm; the forearm is coupled to the upper arm at a first rotary joint and is rotatable about the first rotary joint, the first rotary joint being drivable by a first band mechanism coupled to the second drive shaft; the end effector is coupled to the forearm at a second rotary joint and rotatable about the second rotary joint, the second rotary joint being drivable by a second band mechanism coupled to the first rotary joint, the second band mechanism being configured to provide a variable transmission ratio.

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