Method of aligning an object and robotic object handling system

Abstract

The robotic object handling system includes a robotic arm, non-contact sensors, a first station, and a computing device. The computing device enables the robotic arm to pick up an object from an end effector, positions the object within the detection area of ​​the non-contact sensors, generates sensor data of the object from the non-contact sensors, determines at least one of the rotational error of the object relative to the target orientation or the positional error of the object relative to the target position based on the sensor data, adjusts the robotic arm to approximately eliminate at least one of the rotational error or positional error, and places the object at the first station, wherein the placed object has no rotational error or positional error.

Description

Technical Field

[0001] Embodiments of the present application relate to detecting and correcting misalignment (eg, rotational misalignment) of objects picked up by a robotic arm. Prior Art

[0002] Semiconductor processing and other electronic device processing often utilizes platforms that use robotic arms to transfer objects, such as wafers, between processing chambers, from storage areas (e.g., front-opening pods (FOUPs)) to processing chambers, and from processing chambers to storage areas. In many cases, objects are misaligned when the robotic arm's end effector picks them up. When the end effector picks up an object, the object may include rotational and / or positional errors. Traditionally, this misalignment is corrected by placing the object on an alignment stage, which rotates the object until it is properly aligned. The robotic arm then picks up the aligned object from the alignment stage before moving it to its destination. Using an alignment stage to correct the object's alignment increases the time required to transfer the object between the starting location and the destination and adds additional switching (between the alignment stage and the robotic arm), which can introduce additional errors. Furthermore, the alignment stage consumes valuable space within the platform and the manufacturing facility where it is located, adding to the platform's cost. Additionally, for some objects, the design of the end effector, the adapter for the end effector, and / or the object itself is made to accommodate the alignment stage. However, by designing these components to accommodate the alignment stage, the end effector, the adapter, and / or the object design may not be efficient for other purposes. Summary of the Invention

[0003] Some embodiments described herein include a method for aligning an object. The method may include the following steps: picking up an object on an end effector of a robotic arm. The robotic arm may then be used to place the object within a detection area of ​​a non-contact sensor. While holding the object on the end effector of the robotic arm, sensor data for the object may be generated using the non-contact sensor. Based on the sensor data, at least one of a rotational error of the object relative to a target orientation or a positional error of the object relative to a target position may then be determined. The robotic arm may be adjusted to approximately eliminate at least one of the rotational error or the positional error from the object. The robotic arm may then be used to place the object at a first station, wherein the placed object is free of at least one of a rotational error or a positional error.

[0004] In some embodiments, a robotic object handling system includes: a robotic arm including an end effector; a non-contact sensor having a detection area within the range of the robotic arm; a first station within the range of the robotic arm; and a computing device operably coupled to the non-contact sensor and the robotic arm. The computing device may execute instructions to cause the robotic arm to pick up an object on the end effector. The computing device may further cause the robotic arm to position the object within the detection area of ​​the non-contact sensor. While holding the object on the end effector of the robotic arm, the computing device may further cause the non-contact sensor to generate sensor data for the object. The computing device may further determine, based on the sensor data, at least one of a rotational error of the object relative to a target orientation or a positional error of the object relative to a target position. The computing device may further cause the robotic arm to adjust to approximately eliminate at least one of the rotational error or the positional error from the object. The computing device may further cause the robotic arm to place the object at the first station, wherein the placed object is free of at least one of a rotational error or a positional error.

[0005] In some embodiments, a robotic manipulation system includes: a robotic arm including an end effector; a first station within the range of the robotic arm; a second station within the range of the robotic arm; a non-contact sensor having a detection area in the first station; and a computing device operably coupled to the non-contact sensor and the robotic arm. The computing device may execute instructions to cause the non-contact sensor to generate sensor data for the object when the object is located at the first station. The computing device may further determine a rotational error of the object relative to a target orientation based on the sensor data. The computing device may further determine an angular correction for the object that will approximately eliminate the rotational error of the object. The computing device may further perform the following steps one or more times until the angular correction is achieved for the object: causing the robotic arm to pick up the object from the first station; repositioning the end effector; causing the robotic arm to place the object back on the first station using the repositioned end effector, the object having a reduced rotational error, and then repositioning the end effector. The computing device may further cause the robotic arm to pick up the object again from the first station. The computing device may further cause the robotic arm to place the object at the second station, wherein the object placed at the second station has no rotational error. Simple diagram description

[0006] The present application is illustrated by way of example and not limitation in the figures of the accompanying drawings. In the accompanying drawings, like reference numerals indicate similar elements. It should be noted that different references to "one" or "an" embodiment in this application do not necessarily refer to the same embodiment, and such references mean at least one.

[0007] [ FIG. 1 ] shows a simplified top view of an example processing system according to one aspect of the present application.

[0008] [Figure 2] Depicts a simplified side view of a portion of a processing system according to one aspect of the present application.

[0009] FIG. 3A shows a top view of a misaligned object on an end effector according to one aspect of the present application. FIG.

[0010] [FIG. 3B] shows an embodiment of the present application. [picture] [3A] Top view of the object and end effector, where the end effector has been rotated about the end effector axis to correct for misalignment of the object.

[0011] [ FIG4 ] illustrates a method for correcting misalignment of an object on an end effector of a robotic arm according to one aspect of the present application.

[0012] [ FIG. 5 ] illustrates another method for correcting misalignment of an object on an end effector of a robotic arm according to one aspect of the present application.

[0013] [ FIG. 6 ] illustrates another method for correcting misalignment of an object on an end effector of a robotic arm according to one aspect of the present application.

[0014] [ FIG. 7 ] illustrates another method for iteratively correcting misalignment of an object on an end effector of a robotic arm according to one aspect of the present application. Implementation Method

[0015] Embodiments described herein relate to systems and methods for detecting misalignment of objects picked up and / or held by a robotic arm and correcting such misalignment. Specifically, embodiments enable correction of misalignment of objects picked up by a robotic arm without the use of an alignment stage. In some embodiments, misalignment of an object is correctable while the object is held by the robotic arm. In other embodiments, misalignment of an object is correctable by repeatedly picking up and placing the object at a station that lacks components for realigning the object (e.g., a passive station).

[0016] In some embodiments, a non-contact sensor, such as a camera, is used in conjunction with image processing techniques to determine misalignment of an object and determine a rotational correction (e.g., yaw correction) that will eliminate the misalignment. In one example, the object may be a process kit ring to be inserted into a processing chamber, and the camera may generate an image of the process kit ring held on an end effector of a robotic arm. The image may be processed to determine rotational error and / or positional error of the process kit ring, and the robotic arm may be adjusted (e.g., by rotating the end effector about its axis and / or repositioning it in a plane) to eliminate the rotational error and / or positional error of the process kit ring. The robotic arm may then place the process kit ring on a station (e.g., a transfer station) using the adjustments that eliminate the rotational error and / or positional error.

[0017] Using non-contact sensors (e.g., image sensors) and image processing to determine and correct object misalignment of an object held on an end effector of a robotic arm can eliminate the alignment station from the processing system. This can reduce the overall cost of the processing system and free up additional space for other purposes. Furthermore, by eliminating the alignment station, the number of switches performed to transfer an object from its starting position to its destination can be reduced, which can improve the placement accuracy of the object at its target location (e.g., within a processing chamber) and reduce the time it takes to transfer the object from its starting position to its target location. Furthermore, by eliminating the alignment station, the design constraints imposed by the alignment station can be eliminated, thereby improving the overall design of the object carrier.

[0018] FIG1 illustrates an example processing system 100 according to one aspect of the present application. The processing system 100 includes a factory interface 101 to which a plurality of substrate cassettes 102 (e.g., FOUPs) can be coupled for transferring substrates (e.g., wafers such as silicon wafers) into the processing system 100. The processing system 100 also includes first vacuum ports 103 a and 103 b that can couple the factory interface 101 to respective stations 104 a and 104 b, which can be, for example, degas chambers and / or load locks. Second vacuum ports 105 a and 105 b can be coupled to respective stations 104 a and 104 b and disposed between the stations 104 a and 104 b and a transfer chamber 106 to facilitate transferring substrates into the transfer chamber 106. The transfer chamber 106 includes a plurality of processing chambers (also referred to as "processing chambers") 107 arranged around and coupled to the transfer chamber 106. The processing chambers 107 are coupled to the transfer chamber 106 via corresponding ports 108, such as slit valves.

[0019] The processing chamber 107 may include one or more of an etch chamber, a deposition chamber (including atomic layer deposition, chemical vapor deposition, physical vapor deposition, or plasma-enhanced versions thereof), an annealing chamber, and the like. Some processing chambers 107, such as etch chambers, may include an edge ring (also referred to as a process kit ring) therein, which may sometimes undergo replacement. While the step of replacing the process kit ring in conventional systems involves an operator disassembling the processing chamber to replace the process kit ring, the processing system 100 is configured to facilitate replacement of the process kit ring without requiring an operator to disassemble the processing chamber 107.

[0020] The factory interface 101 includes a factory interface robot 111. The factory interface robot 111 may include a robotic arm and be or include a Selective Compliant Assembly Robot Arm (SCARA) robot, such as a 2-arm SCARA robot, a 3-arm SCARA robot, a 4-arm SCARA robot, and the like. The factory interface robot 111 may include an end effector on the end of the robotic arm. The end effector may be configured to pick up and process specific objects, such as wafers. Alternatively, the end effector may be configured to process objects, such as process kit rings (edge ​​rings). The factory interface robot 111 may be configured to transfer objects between a cassette 102 (e.g., a FOUP) and stations 104a, 104b.

[0021] The transfer chamber 106 includes a transfer chamber robot 112. The transfer chamber robot 112 may include a robotic arm with an end effector at one end. The end effector may be configured to handle a specific object, such as a wafer. The transfer chamber robot 112 may be a SCARA robot, but in some embodiments, the transfer chamber robot 112 may have fewer arms and / or fewer degrees of freedom than the factory interface robot 111.

[0022] In one embodiment, the factory interface 101 includes a non-contact sensor 130a. The non-contact sensor 130a can be an imaging sensor such as a camera. For example, the non-contact sensor 130a can be or include a charge-coupled device (CCD) camera and / or a complementary metal oxide semiconductor (CMOS) camera. Alternatively, the non-contact sensor 130a can include an X-ray emitter (e.g., an X-ray laser) and an X-ray detector. The non-contact sensor 130a can alternatively be or include one or more pairs of a laser emitter that generates a laser beam and a laser receiver that receives the laser beam. Sensor measurements can be generated by a pair of laser emitters and laser receivers (when the laser beam is interrupted so that the laser receiver does not receive the laser beam). This information can be used along with accurate information about the position of the robot arm to generate sensor data, which can be an array of measurements, where each measurement corresponds to a different rotation of the end effector on the factory interface robot 111 and / or a different position of the factory interface robot 111. The non-contact sensor 130 a has a detection area 135 a that is within the range of the robot arm of the factory interface robot 111 .

[0023] In one embodiment, station 104a and / or station 104b includes a non-contact sensor 130b. The non-contact sensor 130b can correspond to any of the non-contact sensors 130a described in the embodiments above. The non-contact sensor 130b has a detection area 135a located within the workstation 104a and further within the range of the robotic arm of the transfer chamber robot 112.

[0024] Controller 109 controls various aspects of processing system 100. Controller 109 may be and / or include a computing device, such as a personal computer, a server computer, a programmable logic controller (PLC), or a microcontroller. Controller 109 may include one or more processing devices, which may be general-purpose processing devices such as microprocessors and central processing units. More specifically, the processing device may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, or a processor that implements another instruction set or a combination of instruction sets. The processing device may also be one or more special-purpose processing devices, such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), and a network processor. Controller 109 may include data storage devices (e.g., one or more disk drives and / or solid-state drives), main memory, static memory, a network interface, and / or other components. Controller 109 may execute instructions to perform any one or more of the methods and / or embodiments described herein. The instructions may be stored on a computer-readable storage medium, which may include main memory, static memory, secondary storage and / or the processing device (during execution of the instructions).

[0025] In an embodiment, the controller 109 may receive signals from the factory interface robot 111, the wafer transfer chamber robot 112, the non-contact sensor 130a and / or the non-contact sensor 130b, and send controls to the factory interface robot 111, the wafer transfer chamber robot 112, the non-contact sensor 130a and / or the non-contact sensor 130b.

[0026] FIG1 schematically illustrates the transfer of an edge ring (or other process kit ring) 110 into a processing chamber 107. According to one aspect of the present application, the edge ring 110 is removed from a cassette 102 (e.g., a FOUP) by a factory interface robot 111 located in the factory interface 101; alternatively, the edge ring 110 is loaded directly into the factory interface 101. While edge rings are discussed herein, it should be understood that the embodiments described with reference to edge rings are also applicable to other process kit rings and objects other than rings.

[0027] In one embodiment, the factory interface robot 111 places the edge ring 110 within the detection area 135a of the non-contact sensor 130a (e.g., below the non-contact sensor 130a). The non-contact sensor 130a generates sensor data of the edge ring 110 (e.g., generates an image of the edge ring). The controller 109 receives the sensor data and analyzes the sensor data (e.g., performs image processing on the received image of the edge ring 110) to determine a rotational error of the edge ring 110 relative to a target orientation of the edge ring 110. For example, the edge ring may include flats, notches, or other alignment features, and the alignment features may have a target orientation relative to the end effector of the factory interface robot 111. The controller 109 may determine the rotational error, which may be a rotational angle between the target orientation and the current orientation of the edge ring 110. The controller 109 may send a command to the factory interface robot 111 to rotate the end effector (and the edge ring 110 supported on the end effector) by a specified amount to correct and eliminate the rotational error. The factory interface robot 111 can then place the edge ring 110 in the station 104a or 104b with the vacuum ports 103a, 103b in the correct orientation. Thus, the degrees of freedom of the factory interface robot 111 can be used to eliminate rotational errors of the edge ring 110 without the need for an alignment station.

[0028] In some embodiments, the factory interface robot 111 can correct for up to a threshold amount of rotational error of the edge ring 110. For example, one factory interface robot 111 can correct for up to 5 degrees of rotational error, while other factory interface robots 111 can correct for up to 3 degrees of rotational error, 7 degrees of rotational error, or some other amount of rotational error. In some embodiments, the factory interface robot 111 can correct for up to a threshold amount of positional error of the edge ring 110 (e.g., if the edge ring is picked up off-center). If the detected rotational error is greater than the threshold amount of rotational error correctable by the factory interface robot 111, the factory interface robot 111 can place the edge ring 110 at a station (not shown), reposition the end effector, and then pick up the edge ring 110 in a manner that eliminates or reduces the rotational error so that the detected rotational error is less than or equal to the threshold amount of rotational error correctable based on the rotation of the end effector. Similarly, if the detected position error is greater than a threshold amount of position error for the edge ring 110 that can be corrected without using a workstation, the factory interface robot 111 can place the edge ring 110 at the workstation, reposition the end effector, and then retrieve the edge ring 110 in a manner that eliminates or reduces the position error so that it is less than or equal to the threshold amount of position error that can be corrected based on the repositioned end effector. Additionally, both rotational error and positional error can be corrected together (e.g., by rotating and / or repositioning the end effector, and / or by placing the edge ring at the workstation and then retrieving the edge ring with the repositioned and / or rotated end effector). In some embodiments, the remaining rotational error (which can be zero) of the edge ring after the factory interface robot 111 picks the edge ring 110 from the workstation is known (e.g., based on the known orientation of the edge ring 110 when placed at the workstation and the known orientation of the end effector that picked up the edge ring 110). Alternatively, the edge ring 110 can be placed again within the detection area 135a of the non-contact sensor 130a, and additional sensor data can be generated. A new determination of the rotational error of the edge ring 110 can then be made from the additional sensor data, and further angular corrections can be made to the edge ring 110 as described above. The edge ring 110 can then be placed in the stations 104a, 104b without rotational error and / or positional error (also known as translational error).

[0029] A transfer chamber robot 112 located in the transfer chamber 106 removes the edge ring 110 from one of the stations 104a, 104b via the second vacuum port 105a or 105b. The transfer chamber robot 112 moves the edge ring 110 (now in the correct orientation) into the transfer chamber 106, where it can be transferred to the target processing chamber 107 via the corresponding port 108.

[0030] In some embodiments, the non-contact sensor 130a is not used. Therefore, the factory interface robot 111 may place the edge ring 110 in the station 104a with a certain degree of misalignment (e.g., rotational error and / or positional error). In such embodiments, the station 104a may include a non-contact sensor 130b that can generate sensor data (e.g., generate an image of the edge ring) of the edge ring 110 while the edge ring 110 is in the station 104a. The transfer station 104a may be a load lock or other station having a transparent window on top of the transfer station 104a. The non-contact sensor 130b may be an imaging sensor that can generate an image of the edge ring 110 through the transparent window. In some embodiments, the interior of the station 104a may be in a vacuum, but the non-contact sensor 104a may not be in a vacuum. The controller 109 receives the sensor data and analyzes the sensor data (e.g., performing image processing on a received image of the edge ring 110) to determine a rotation error and / or a position error of the edge ring 110 relative to a target orientation and / or a position of the edge ring 110. The controller 109 may determine the rotation error, which may be a rotation angle between the target orientation and the current orientation of the edge ring 110.

[0031] The controller 109 can then determine a sequence for picking and placing edge ring 110 at station 104a that will eliminate rotational and / or positional errors. Conventionally, the transfer chamber robot 112 can pick up an object approximately at its center and place it at the center of the station. However, the controller 109 may cause the transfer chamber robot 112 to pick up edge ring 110 (optionally off-center), slightly change its position, place edge ring 110 at a location off-center (different from the location from which it was picked up from station 104a), slightly change its position, pick up edge ring 110 again (optionally off-center), and so on. Each sequence of picking, placing, and replacing edge ring 110 at station 104a can slightly adjust the edge ring's rotation or yaw. Additionally, the edge ring's position can be slightly adjusted. Thus, a series of picks and places can be performed to correct for detected rotational and / or positional errors. Once the rotational error and / or positional error has been corrected, the transfer chamber robot 112 removes the edge ring 110 from the station 104a via the second vacuum port 105a. The transfer chamber robot 112 moves the edge ring 110 (now correctly oriented) into the transfer chamber 106, where it can be transferred to the desired processing chamber 107 via the corresponding port 108.

[0032] Although not included for clarity [picture] [1] shows that when the edge ring 110 is positioned on a carrier or adapter, transfer of the edge ring 110 can occur and the end effector can pick up and place the carrier or adapter holding the edge ring 110. This can enable an end effector configured for processing wafers to also process the edge ring 110.

[0033] FIG1 illustrates one example of edge ring transport, but other examples are contemplated. For example, an edge ring may be loaded into a substrate support pedestal (SSP). An additional SSP may be positioned to communicate with a factory interface 101 opposite the illustrated SSP.

[0034] It is contemplated that the processed edge ring 110 may be removed from the processing system 100 in a manner opposite to any of the methods described herein. For such a process, a carrier designed to hold the edge ring 110 may be removed from the cassette 102 by the factory interface robot 111. The factory interface robot 110 may position the empty carrier within the detection area 135b of the non-contact sensor 130a. Sensor data may then be generated, and the controller 109 may analyze the sensor data to determine the orientation of the carrier and whether the carrier has any rotational and / or positional errors. If the carrier has rotational errors, the rotational errors may be corrected as described above. Similarly, if the carrier has positional errors, the positional errors may be corrected as described above. The carrier, with the correct orientation and / or position, may then be placed at the stations 104a, 104b and removed by the transfer chamber robot 112 for insertion into the processing chamber 107. The used edge ring 110 may then be placed on a carrier and then may be transferred back through the stations 104a, 104b and into the cassette 102 using processing via the transfer chamber robot 112 and the factory interface robot 111.

[0035] Additionally or alternatively, the carrier may be placed in station 104a without correcting its orientation and / or position. In such an embodiment, the contactless sensor 130b may be used to determine any rotational errors and / or positional errors in the carrier, which may then be corrected in the manner described above.

[0036] When two SSPs or multiple cassettes 102 are utilized, it is contemplated that one SSP or cassette 102 may be used for unprocessed edge rings 110 while another SSP or cassette 102 may be used to receive processed edge rings 110 .

[0037] [Figure 2] depicts a simplified side view of a portion 200 of a processing system 100 according to one aspect of the present application. Specifically, the portion 200 of the processing system 100 includes a factory interface 101 and a controller 109. As shown, the factory interface robot 111 includes a robotic arm 210 having an end effector (also known as a robot blade) 215 at one end of the robotic arm 210. The edge ring 110 is supported on the end effector 215. The controller 109 causes the factory interface robot 111 to position the edge ring 110 below the non-contact sensor 130a in the detection area 135a of the non-contact sensor 130a. The non-contact sensor 130a can then generate sensor data (e.g., one or more images) and send the images to the controller 109 for processing as described above. [picture] [1]

[0038] The correction of the rotational error and / or positional error of the edge ring 110 has been described with reference to [picture] [1] [Go to Figure 2.] However, it should be understood that the same systems and techniques described with reference to edge rings can also be used to detect and correct rotational errors and / or positional errors of other objects, such as wafers, display panels, consumable parts for processing chambers, and photomasks.

[0039] FIG3A shows a top view of a misaligned object on the end effector 215 of the robot arm 210 according to one aspect of the present application. The misaligned object may be the edge ring 110 described above. However, the misaligned object may alternatively be a display panel, a photolithography mask, a wafer (e.g., a semiconductor wafer or silicon wafer), or other object with a target orientation. Generally, the object will be a relatively flat object with a height several orders of magnitude smaller than its diameter, length, and / or width.

[0040] As shown, the edge ring 110 has an alignment feature 320. In the illustrated embodiment, the alignment feature 320 is a flat surface on the inner edge of the edge ring 110. However, other types of alignment features may be used, such as a flat surface located elsewhere on the edge ring (or other object), a fiducial in the edge ring (or other object), one or more notches in the edge ring (or other object), and so forth. Also shown, the alignment feature 320 is rotated relative to the front of the end effector 215, indicating that the edge ring 110 has been incorrectly placed on the end effector 215, thereby introducing a rotational error. The factory interface robot 111 may have sufficient degrees of freedom to rotate the end effector 215 (and the edge ring 110 held thereon) about an end effector axis 330. The end effector axis 330 may be an axis (e.g., a vertical axis) that approximately corresponds to the center of the edge ring 110 supported by the end effector 215. Thus, the end effector 215 and edge ring 110 can effectively rotate, optionally without introducing translational movement (eg, left, right, front, or back) to the edge ring 110 .

[0041] [Figure 3B] shows [picture] [3A] is a top view of an object and end effector 215, wherein according to one aspect of the present application, the end effector 215 and edge ring 110 have been rotated about the end effector axis 330 to correct for misalignment of the edge ring 110. The rotation can be performed after generating sensor data (e.g., image data) using a non-contact sensor such as a camera and then processing the sensor data to determine a rotational error of the edge ring 110.

[0042] In some embodiments, edge ring 110 can be supported by carrier 315. Carrier 315 can be designed to interface with both end effector 215 and edge ring 110, enabling end effector 215 to support edge ring 110. As shown, carrier 315 includes pins 325 for securing edge ring 110. Pins 325 can also serve as alignment features for carrier 315. Thus, the contactless sensors described above can generate sensor data for carrier 315 to determine the orientation (and possibly rotational error) of carrier 315. Rotational errors in carrier 315 can be accounted for in the same manner as described above for edge ring 110.

[0043] As described above, edge ring 110 can have a target orientation relative to end effector 215. Additionally, edge ring 110 can also have a target orientation relative to carrier 315. Specifically, in one embodiment, the target orientation of edge ring 110 aligns the flat surface of the edge ring (alignment feature 320) with the pins of carrier 315 (alignment feature 325). In some embodiments, the orientation of edge ring 110 may not align with the orientation of carrier 315. Sensor data from a non-contact sensor can be used to determine both the orientation of edge ring 110 and the orientation of carrier 315. The difference between these two orientations (e.g., a rotational angle) can then be determined by controller 109. If the difference exceeds a threshold, controller 109 can decide not to use edge ring 110 and carrier 315 and return the carrier and adapter to their starting positions (e.g., back to the FOUP). In some embodiments, if edge ring 110 has a first rotational error relative to end effector 215 and carrier 315 has a second rotational error relative to end effector 215, the angular correction performed will eliminate the first rotational error (rather than the second rotational error).

[0044] [Figure 4] [Figure 7] is a flowchart of various embodiments of methods 400 to 700 for correcting misalignment of an object on an end effector of a robotic arm. The methods are performed by processing logic, which may include hardware (circuitry, dedicated logic, etc.), software (such as software running on a general-purpose computer system or a dedicated machine), firmware, or some combination of the above. Some methods 400 to 600 may be performed by, for example, [picture] [1] The processing logic for performing one or more operations of methods 400 to 600 may be executed on the controller 109 of FIG. 2 , which controls the robotic arm and / or the contactless sensor.

[0045] For simplicity of explanation, the method is illustrated and described as a series of acts. However, the acts according to the present application may occur in various orders and / or simultaneously, and with other acts not shown or described herein. Furthermore, not all illustrated acts may be performed to implement the method according to the subject matter disclosed herein. Furthermore, one of ordinary skill in the art will understand and appreciate that a method may alternatively be represented as a series of interrelated states via a state diagram or events.

[0046] FIG4 illustrates a method 400 for correcting misalignment of an object on an end effector of a robot according to one aspect of the present application. At block 410 of method 400, the robot (e.g., based on instructions from a computing device) picks up an object on the end effector of the robot. The object can be any of the aforementioned objects, such as a process kit ring. For example, the object can be a process kit ring that includes an alignment feature, wherein the alignment feature is a flat surface that is oriented to fit into and mate with a corresponding flat surface on a substrate support assembly on which the process kit ring will be placed.

[0047] At block 420, the robotic arm positions the object within the detection area of ​​the contactless sensor. For example, the contactless sensor may be a camera, and the robotic arm may position the object within the field of view of the camera.

[0048] At block 430 , the contactless sensor generates sensor data of the object while holding the object on the end effector of the robotic arm (eg, based on instructions from a computing device).

[0049] At block 440, processing logic determines a rotational error of the object relative to a target orientation of the object and / or a positional error of the object relative to a target position of the object based on the sensor data. The target orientation can be a target orientation relative to an orientation of the end effector. Similarly, the target position can be a target position relative to the end effector.

[0050] In some embodiments, the sensor is a camera, and the sensor data includes one or more images of an object on the end effector. In such embodiments, rotational error and / or positional error of the object can be determined by performing image processing on the one or more images. For example, the object can have a known shape and / or can include one or more alignment features (e.g., flat surfaces, notches, fiducials, etc.). Image processing can be performed to determine the position and / or orientation of the one or more alignment features. Using, for example, encoders and / or sensors in a robotic arm to which the end effector is mounted, the position and orientation of the end effector can be known with a high degree of certainty. Thus, a determined position and / or orientation of the object relative to the position and / or orientation of the end effector can be determined.

[0051] In one embodiment, a Hough transform is performed to determine the rotation error of an object. Processing logic uses the Hough transform and prior knowledge of the object's shape (e.g., a plane on the object) to determine the position and orientation of the plane. Other standard image processing techniques can also be used to determine the object's orientation, such as edge detection, slope calculation, voting algorithms, oriented FAST, and rotated BRIEF (ORB) image processing techniques.

[0052] At block 445, processing logic determines an angular correction of the object that will approximately or completely eliminate the object's rotational error. At block 450, processing logic repositions the robotic arm to rotate the end effector and implement the angular correction and / or correct the positional error. In one embodiment, the end effector can effectively rotate about the end effector axis.

[0053] At block 455, processing logic causes the robotic arm to place the object at a first station (e.g., a transfer station or load lock) using the robotic arm with the rotated and / or repositioned end effector. The placed object is free of rotational and / or positional errors. Correction for angular and / or positional errors can be performed using the robotic arm's degrees of freedom and without the use of an aligner. In some embodiments, the operations of block 450 and block 455 are performed together such that rotation and / or repositioning of the end effector is accomplished as the object is moved to the first station. For example, the end effector may be slightly rotated upon placement of the object at the first station to provide the determined angular correction for the object.

[0054] Compared to conventional techniques for eliminating rotational errors (e.g., using an aligner), method 400 can improve the accuracy of the orientation (e.g., rotation or yaw) of an object, such as an edge ring. Furthermore, method 400 can be used to determine and correct rotational errors for many different types of objects that may not be amenable to alignment stages. Method 400 enables the elimination of alignment stations from processing systems (e.g., wafer processing systems). As discussed above, eliminating alignment stages also offers other benefits.

[0055] FIG5 illustrates another method 500 for correcting misalignment of an object on an end effector of a robotic arm according to one aspect of the present application. At block 510 of method 500, the robotic arm (e.g., based on instructions from a computing device) picks up an object on the end effector of the robotic arm. The object can be any of the aforementioned objects, such as a processing kit ring. At block 520, the robotic arm positions the object within a detection area of ​​a non-contact sensor. For example, the non-contact sensor can be a camera, and the robotic arm can position the object within the camera's field of view.

[0056] At block 530, while the object is held on the end effector of the robotic arm (e.g., based on instructions from a computing device), the contactless sensor generates sensor data for the object. At block 540, processing logic determines a rotational error of the object relative to a target orientation of the object and / or determines a positional error of the object relative to a target position of the object on the end effector. The target orientation can be a target orientation relative to an orientation of the end effector.

[0057] In some embodiments, the sensor is a camera, and the sensor data includes one or more images of an object on the end effector. In such embodiments, the rotational error of the object can be determined by performing image processing on the one or more images. For example, the object can have a known shape and / or can include one or more alignment features (e.g., flat surfaces, notches, fiducials, etc.). Image processing can be performed to determine the orientation of the one or more alignment features and / or the position of the one or more alignment features. Using, for example, encoders and / or sensors in a robotic arm to which the end effector is mounted, the position and orientation of the end effector can be known with a high degree of certainty. Thus, a determined orientation and / or position of the object relative to the orientation and / or position of the end effector can be determined.

[0058] In one embodiment, a Hough transform is performed to determine the rotation error of an object. Processing logic uses the Hough transform and prior knowledge of the object's shape (e.g., a plane on the object) to determine the position and orientation of the plane. Other standard image processing techniques can also be used to determine the object's orientation, such as edge detection, slope calculation, voting algorithms, oriented FAST, and rotated BRIEF (ORB) image processing techniques.

[0059] At block 545, processing logic determines an angular correction for the object that will approximately or completely eliminate the object's rotational error and / or a position correction that will approximately or completely eliminate the object's positional error. At block 550, processing logic determines whether the angular correction exceeds a first threshold and / or whether the position correction exceeds a second threshold. The first threshold may be based on an amount of rotation that can be performed about the end effector axis when the end effector axis is at the station on which the end effector is to drop the object. Some exemplary thresholds are 3 degrees, 4 degrees, 5 degrees, 6 degrees, 7 degrees, and so on. If the determined angular correction (corresponding to the rotational error) exceeds the first threshold, the method may proceed to block 560. Similarly, if the position correction exceeds the second threshold, the method may proceed to block 560. If the determined angular correction is less than or equal to the first threshold (and optionally, if the position correction is less than or equal to the second threshold), the method may continue to block 555.

[0060] At block 560, processing logic causes the robotic arm to place the object at the first station. At block 565, the robotic arm (and end effector) is repositioned. The end effector can be repositioned in a manner that reduces or eliminates rotational and / or positional errors once the object is retrieved. At block 570, the robotic arm uses the repositioned end effector to pick up the object from the first station.

[0061] At block 575, processing logic may determine whether the calculated angle correction has been implemented (such that the rotation error is eliminated) and / or whether the calculated position correction has been implemented. If the angle correction and / or position correction has been implemented, the method continues to block 575. If a remaining rotation error and / or a remaining position error exists, the method continues to block 578.

[0062] At block 578, processing logic determines whether the residual rotation error is less than or equal to a first threshold and / or whether the residual position error is less than or equal to a second threshold. If the residual rotation error is greater than the first threshold, the method returns to block 560. If the residual error is less than or equal to the first threshold, it can be corrected using the robot's degrees of freedom and the method continues to block 555. A similar determination can be made for the residual position error.

[0063] At block 555, processing logic repositions the robotic arm to rotate the end effector and implement angle correction and / or correct position errors. In an embodiment, the end effector can effectively rotate about the end effector axis.

[0064] At block 580, processing logic causes the robotic arm to place the object at a second station (e.g., a transfer station or a load lock). The object is placed without rotational error. Correction for angular error can be performed without the use of an aligner.

[0065] FIG6 illustrates another method 600 for correcting misalignment of an object on an end effector of a robotic arm according to one aspect of the present application. At block 602 of method 600, a non-contact sensor (e.g., a camera) is used to generate sensor data for an object positioned at a first station. At block 605, processing logic determines a rotational error of the object relative to a target orientation of the object based on the sensor data and / or determines a positional error of the object relative to a target position of the object based on the sensor data. At block 615, processing logic determines an angular correction of the object that will approximately eliminate the rotational error of the object and / or determines a positional correction of the object that will approximately eliminate the positional error of the object. Determining the angular correction may include determining a number of object pickups and dropoffs using the end effector and positioning the end effector for each pickup and dropoff that will correct the rotational error. A portion of the angular correction to be applied for each pickup and dropoff may be determined. In general, multiple pickups and dropoffs of the object at the first station may eliminate rotational error and / or positional error. In some embodiments, only the rotational error is corrected. In other embodiments, only the positional error is corrected. In other embodiments, both angular error and position error are corrected.

[0066] At block 620, the robot arm (e.g., based on instructions from a computing device) picks up an object on the end effector of the robot arm. The object can be any of the aforementioned objects, such as a process kit ring. For example, the object can be a process kit ring that includes an alignment feature, wherein the alignment feature is a flat surface that is properly oriented to align with and mate with a corresponding flat surface on the substrate support assembly on which the process kit ring will be placed.

[0067] At block 630, the robotic arm is adjusted to reposition the end effector. At block 640, the object is returned to the first station using the repositioned end effector. At this point, the object will have a slightly reduced rotational error and / or a slightly reduced positional error, which may have been calculated at block 615.

[0068] At block 650, the end effector is repositioned again. At block 660, the object is picked up again from the first station using the repositioned end effector.

[0069] At block 670, processing logic determines whether angle correction has been applied (to eliminate rotational errors) and / or whether position correction has been completed. If angle correction has not been applied, the method returns to block 630 and another round of pick-up and lowering is performed. If angle correction has been applied, the method continues to block 680. Similar decisions can be made for position correction.

[0070] At block 680, processing logic causes the robotic arm to place the object at the second station (e.g., in a processing chamber) using the robotic arm. The placed object is free of rotational error and / or positional error. Correction of rotational error in method 600 can be performed using a robotic arm that does not have a degree of freedom to rotate the object about the end-effector axis of the robotic arm's end-effector. However, repeatedly picking up and placing the object at the first station provides the robotic arm with a virtual degree of freedom, thereby correcting rotational errors less than a rotational error threshold.

[0071] FIG7 illustrates a method 700 for progressively correcting misalignment of an object on an end effector of a robotic arm according to one aspect of the present application. At block 710 of method 700, the robotic arm (e.g., based on instructions from a computing device) picks up an object on the end effector of the robotic arm. The object can be any of the aforementioned objects, such as a process kit ring. For example, the object can be a process kit ring that includes an alignment feature, wherein the alignment feature is a flat surface that is oriented to align with and mate with a corresponding flat surface on a substrate support assembly on which the process kit ring is to be placed. The robotic arm then positions the object within a detection area of ​​a non-contact sensor. For example, the non-contact sensor can be a camera, and the robotic arm can position the object within the camera's field of view.

[0072] At block 715 , the contactless sensor generates sensor data of the object while holding the object on the end effector of the robotic arm (eg, based on instructions from a computing device).

[0073] At block 720, processing logic determines a rotational error of the object relative to a target orientation of the object and / or determines a positional error of the object relative to a target position of the object based on the sensor data. The target orientation can be a target orientation relative to an orientation of the end effector. Similarly, the target position can be a target position relative to the end effector.

[0074] At block 725, processing logic performs a first correction of position error and / or rotation error using one or more of the techniques described above.

[0075] At block 730, the robotic arm repositions the object within the detection area of ​​the contactless sensor. At block 735, the contactless sensor generates additional sensor data of the object while holding the object on the end effector of the robotic arm (e.g., based on instructions from the computing device).

[0076] At block 740, processing logic determines a residual rotational error of the object relative to the target orientation of the object and / or a residual positional error of the object relative to the target position of the object based on the sensor data. The robotic arm may exceed or fall short of the target correction for rotation and / or position. For example, the computing device may have instructed the robotic arm to rotate the held object by 4 degrees, but the robotic arm may have actually rotated the held object by only 3.7 degrees. The second sensor data can detect such inaccuracies and identify any residual errors.

[0077] At block 745, processing logic determines whether the angle correction and / or position correction is achieved within a threshold level of accuracy (e.g., within 0.1 mm or 0.1 degrees). If the angle correction and / or position correction is achieved within the threshold level of accuracy, the method may proceed to block 755. If the angle correction and / or position correction is not achieved within the threshold level of accuracy, the method may continue to block 750.

[0078] At block 750, processing logic causes the robotic arm to perform a second correction on the remaining position error and / or the remaining rotation error. The method may then proceed to block 755. Alternatively, the operations of blocks 740 through 750 may be repeated one or more (additional) times. With each iteration of these operations, the amount of residual error will be less, and therefore the amount of correction to be performed will be less.

[0079] At block 755, processing logic causes the robotic arm to place the object at a first station (e.g., a transfer station or a load lock) using the robotic arm with the rotated and / or repositioned end effector. The object is placed without rotational error and / or positional error. Correction for angular error and / or positional error can be performed using the robotic arm's degrees of freedom and without the use of an aligner.

[0080] The foregoing description sets forth numerous specific details, such as examples of specific systems, components, methods, and the like, to provide a good understanding of several embodiments of the present application. However, it will be apparent to one of ordinary skill in the art that at least some embodiments of the present application can be practiced without these specific details. In other instances, well-known components or methods are not described in detail or presented in a simple block diagram format to avoid unnecessarily obscuring the present application. Therefore, the specific details set forth are merely illustrative. Specific implementations may differ from these illustrative details and still be contemplated within the scope of the present application.

[0081] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Additionally, the term "or" is intended to be inclusive rather than exclusive. When the terms "about" or "approximately" are used herein, this is intended to indicate that the stated nominal value is accurate to within ±10%.

[0082] Although the operations of the methods herein are shown and described in a particular order, the order of operations of each method may be changed such that certain operations may be performed in a reverse order or such that certain operations may be performed at least partially concurrently with other operations. In another embodiment, instructions or sub-operations of different operations may be performed in a periodic and / or alternating manner.

[0083] It should be understood that the above description is intended to be illustrative and not restrictive. Many other embodiments will become apparent to those skilled in the art upon reading and understanding the above description. Accordingly, the scope of this application should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0084] 100:Processing system 101:Factory Interface 102: substrate box 103a, 103b: First vacuum port 104a,104b:Station 105a, 105b: Second vacuum port 106:Transfer chamber 107: Processing chamber 108: corresponding port 109:Controller 110:Edge Ring 111:Factory Interface Robot 112:Transfer Chamber Robot 130a, 130b: non-contact sensor 135a, 135b: Detection area 200: Part 210:Robotic Arm 215: End Effector 315:Carrier 320: Alignment feature 325: Pin 330: End effector shaft 400:Method 410~455: Box 500:Method 510~580: Square 600:Method 602~680: Box 700: Method 710~755: Square

[0085] Domestic storage information (please note the order of storage institution, date, and number) none Overseas deposit information (please note the order of deposit country, institution, date, and number) none

Claims

1. A method for aligning an object, comprising the steps of: picking up the object from an end effector of a robotic arm; while holding the object on the end effector of the robotic arm, generating an image of the object on the end effector using an image sensor; determining at least one of: (i) a rotational error of the object based on an orientation of an alignment feature reflected in the image of the object, or (ii) a positional error of the object based on a position of an alignment feature reflected in the image of the object; adjusting the robotic arm to approximately eliminate at least one of the rotational error or the positional error; and placing the object at a first station without at least one of the rotational error or the positional error using the robotic arm.

2. The method of claim 1, wherein the robotic arm includes one or more joints that enable the end effector to rotate about an end effector axis by a threshold amount, the method further comprising the steps of: determining an angle correction for the object, the angle correction approximately eliminating the rotational error of the object; wherein the step of adjusting the robotic arm to approximately eliminate the rotational error from the object comprises the steps of: rotating the end effector of the robotic arm to implement the angle correction, and wherein the placement step is performed using the end effector rotated to implement the angle correction.

3. The method as described in claim 2 further includes the step of: determining a threshold amount by which the angle correction is less than or equal to the rotation.

4. The method of claim 1, wherein the robotic arm includes one or more joints that enable the end effector to rotate about an end effector axis to a threshold amount, the method further comprising the steps of: determining an angle correction for the object, the angle correction approximately eliminating the rotational error of the object; and determining that the angle correction is greater than the rotational threshold amount; wherein the step of adjusting the robotic arm to approximately eliminate the rotational error from the object comprises the steps of: performing the following steps once or more until a) the angle correction is applied to the object or b) a remaining angle error is less than the rotational threshold amount of the end effector: placing the object at a second station; repositioning the end effector; and using the repositioned end effector to pick up the object from the second station, wherein after picking up the object from the second station, the object has a reduced rotational error.

5. The method as described in claim 4, wherein the object has a small positional error after being picked up from the second station.

6. The method of claim 1, wherein the robotic arm includes one or more joints that enable the end effector to rotate about an end effector axis by a threshold amount, and wherein the robotic arm is capable of correcting to a position error threshold amount without using a second station, the method further comprising the steps of: determining an angle correction for the object that will approximately eliminate the rotational error of the object; determining a position correction that will approximately eliminate the positional error of the object; determining at least one of a) the angle correction being greater than the rotational threshold amount or b) the positional error being greater than the positional error threshold amount; wherein the step of adjusting the robotic arm to approximately eliminate at least one of the rotational error or the positional error from the object comprises the steps of performing the following steps once or more: placing the object at the second station; repositioning the end effector; and picking up the object from the second station using the repositioned end effector, wherein after picking up the object from the second station, the object has at least one of a reduced rotational error or a smaller positional error.

7. The method of claim 1, wherein the robotic arm lacks the capability to rotate the end effector about an end effector axis, the method further comprising the steps of: determining an angle correction for the object, the angle correction approximately eliminating the rotational error of the object; wherein adjusting the robotic arm to approximately eliminate the rotational error from the object comprises the steps of: performing the following steps once or multiple times until the angle correction for the object is completed: placing the object at a second station; repositioning the end effector; and using the repositioned end effector to pick up the object from the second station, wherein the object has a reduced rotational error.

8. The method as described in claim 7, wherein the object has a small positional error after being picked up from the second station.

9. The method as claimed in claim 1, wherein the step of generating the image of the object includes the steps of: using the image sensor to generate one or more images, and wherein the step of determining the rotation error of the object includes the steps of: performing image processing on the one or more images to identify an orientation of at least one of a plane, a notch, or a reference in the object.

10. The method of claim 1, wherein the object is attached to a carrier, wherein the step of picking up the object includes the step of picking up the carrier attached to the object, and wherein the step of placing the object includes the step of placing the carrier attached to the object, the method further comprising the steps of: generating sensor data of the carrier using an image sensor; and determining a rotational error of the carrier based on the sensor data of the carrier.

11. The method as described in claim 10 further includes the following steps: comparing the rotational error of the carrier with the rotational error of the object; determining a difference between the rotational error of the carrier and the rotational error of the object based on the comparison; determining whether the difference exceeds a threshold; and in response to determining that the difference does not exceed the threshold, placing the object at the first station.

12. The method of claim 1, further comprising the steps of: picking up a carrier of a second object attached to the end effector of the robotic arm from a first position; generating new sensor data of the carrier and the object using an image sensor while the carrier is held on the end effector of the robotic arm; determining an orientation of the carrier based on the new sensor data; determining an orientation of the second object based on the new sensor data; determining a difference between the orientation of the carrier and the orientation of the object; determining whether the difference exceeds a threshold; and, in response to determining that the difference exceeds the threshold, returning the carrier and the object to the first position.

13. The method as described in claim 1, wherein the object includes a consumable component for a processing chamber.

14. The method of claim 1, wherein the image sensor includes a laser transmitter that generates a laser beam and a laser receiver that receives the laser beam, wherein the step of generating the image of the object includes the following steps: repeating (a) extending the end effector until the object is located between the laser transmitter and the laser receiver and interrupting the laser beam so that the laser beam is no longer received by the laser receiver, and (b) recording one or more parameters of the robotic arm at the point where the laser beam is interrupted on the object, the one or more parameters including a rotation of the end effector and a position of the end effector; generating a measurement array, wherein each measurement corresponds to a different rotation of the end effector; and determining a rotation angle of the object based on the measurement array.

15. The method as claimed in claim 1, further comprising the steps of: after adjusting the robotic arm and before placing the object at the first station, performing the following steps: generating an additional image of the object using the image sensor; determining, based on the image, at least one of a residual rotational error or a residual positional error of the object; and further adjusting the robotic arm to approximately eliminate at least one of the residual rotational error or the residual positional error from the object.

16. A robotic object handling system, comprising: A robotic arm, the robotic arm including an end effector; An image sensor; the first station; The system also includes a computing device operatively coupled to the image sensor and the robotic arm, wherein the computing device performs the following steps: causing the robotic arm to pick up an object from the end effector; while the object is held on the end effector of the robotic arm, causing the image sensor to generate an image of the object on the end effector; determining at least one of the following: (i) determining a rotational error of the object based on the orientation of an alignment feature reflected in the image of the object, or (ii) determining a positional error of the object based on the position of an alignment feature reflected in the image of the object; causing the robotic arm to make an adjustment to approximately eliminate at least one of the rotational error or the positional error; and causing the robotic arm to place the object at the first station without at least one of the rotational error or the positional error.

17. The robotic object handling system of claim 16, wherein the robotic arm includes one or more joints that enable the end effector to rotate about an end effector axis by a threshold amount, wherein the computing device further performs the following steps: determining an angle correction for the object, the angle correction approximately eliminating the rotational error of the object; wherein the step of adjusting the robotic arm to approximately eliminate the rotational error from the object includes the steps of: rotating the end effector of the robotic arm to implement the angle correction, and wherein the placement step is performed using the end effector rotated to implement the angle correction.

18. The robot object handling system as claimed in claim 17, wherein the computing device further performs the following steps: determining that the angle correction is less than or equal to a threshold amount of the rotation.

19. The robotic object handling system of claim 16, wherein the robotic arm includes one or more joints that enable the end effector to rotate about an end effector axis by a threshold amount, wherein the computing device further performs the following steps: determining an angle correction for the object that will approximately eliminate the rotational error of the object; and determining that the angle correction is greater than the rotational threshold amount; wherein the step of adjusting the robotic arm to approximately eliminate the rotational error from the object includes performing the following steps once or more until a) the angle correction is applied to the object or b) a remaining angle error is less than the rotational threshold amount of the end effector: placing the object at a second station having an initial position and orientation; repositioning the end effector; and picking up the object from the second station using the repositioned end effector, wherein after picking up the object from the second station, the object has a reduced rotational error.

20. The robot object processing system of claim 16, wherein the step of generating the image of the object includes the steps of: using an image sensor to generate one or more images, and wherein the step of determining the rotational error of the object includes the steps of: performing image processing on the one or more images to identify an orientation of at least one of a plane, a notch, or a reference in the object.

21. The robot object handling system of claim 16, wherein the object is attached to a carrier, wherein the step of picking up the object includes the steps of: picking up the carrier attached to the object, and wherein the step of placing the object includes the steps of: placing the carrier attached to the object, wherein the computing device further performs the steps of: generating sensor data of the carrier using an image sensor; and determining a rotational error of the carrier based on the sensor data of the carrier.

22. The robotic object handling system as claimed in claim 21, wherein the computing device further performs the following steps: comparing the rotational error of the carrier with the rotational error of the object; determining a difference between the rotational error of the carrier and the rotational error of the object based on the comparison; determining whether the difference exceeds a threshold; and in response to determining that the difference does not exceed the threshold, causing the robotic arm to place the object at the first station.

23. A robot processing system, comprising: A robotic arm, the robotic arm including an end effector; a first station; The second stop; An image sensor; The system also includes a computing device operatively coupled to the image sensor and the robotic arm, wherein the computing device performs the following steps: causing the image sensor to generate an image of the object on the end effector when the object is located at the first station; determining a rotational error of the object based on an orientation of an alignment feature reflected in the image of the object; determining an angle correction for the object that will approximately eliminate the rotational error; and performing the following steps once or multiple times until the angle correction for the object is completed: causing the robotic arm to pick up the object from the first station; repositioning the end effector; and causing the robotic arm to use the repositioned end effector to place the object back on the first station, the object having a reduced rotational error. And reposition the end effector; so that the robotic arm picks up the object again from the first station; and so that the robotic arm places the object at the second station without the rotation error.

Images