Grasping detection system for liquid handling robots

Abstract

A liquid handling robot has a workbench that supports a rack that holds a set of pipette tips. The liquid handling robot also has an arm operably suspended above the workbench, wherein the arm includes a tip receptacle configured to engage the set of pipette tips. A controller of the liquid handling robot is configured to raise the tip receptacle away from the workbench to remove the engaged set of pipette tips from the rack. A sensor is fixed relative to the workbench and is operable to emit a light beam. A microcontroller monitors the sensor with the arm in a checking position to determine if a rack interrupts the light beam to indicate that the rack is stuck on a pipette tip, which is automatically resolved by the liquid handling robot performing a corrective action.

Description

Technical Field

[0001] The present disclosure relates to liquid handling robots, such as liquid handlers, having gripping devices for picking up pipette tips and tubes in a laboratory. Background Art

[0002] In addition to the primary function of pipetting, liquid handling robots also perform complex tasks, including manipulating plates and tubes, and automatically changing disposable pipette tips. During the execution of these tasks, mechanical errors may occur, such as unsuccessful grasping and jamming. To prevent such errors from causing damage to the equipment, the further execution of consecutive steps of the task can be conditional on whether the manipulation step is successful. For example, the liquid carrier can be programmed to display user prompts and wait for confirmation from a human after a problematic or failure-prone manipulation step. Human intervention and observation of such tasks require the liquid handling robot to run these tasks during working hours, which reduces efficiency, prevents the robot from running outside of human working hours, and may cause damage. Summary of the Invention

[0003] One aspect of the present disclosure provides a liquid handling robot system having a station structure with a workbench configured to support liquid containers, such as well plates, tubes, and the like. A rack holding a set of pipette tips is disposed at a home position within the station structure. A liquid handling robot is coupled to the station structure and has an arm suspended above the workbench, wherein the arm includes a tip receptacle configured to engage a set of pipette tips from the rack. A controller of the liquid handling robot is configured to control movement of the arm relative to the workbench, such that the controller is configured to move the arm to a position above the rack. In this position, the controller can control the liquid handling robot to engage the tip receptacle with the set of pipette tips held in the rack, and then raise the tip receptacle away from the home position to remove the engaged set of pipette tips from the rack. The controller can then control the liquid handling robot to move the engaged set of pipette tips to a liquid container to introduce liquid from the liquid container into at least one of the pipette tips engaged with the tip receptacle.

[0004] In some cases, the set of pipette tips engaged with the tip receptacle may frictionally engage the rack when being removed, causing the rack to be held in a stuck state by the tips. A liquid handling robot system according to one aspect of the present disclosure provides a sensor configured to emit a light beam and sense an interruption of the light beam. The sensor may be coupled to a station structure or an arm of a liquid handling robot. After the tip receptacle engages the set of pipette tips held in the rack and the engaged tips are raised from an original position, the light beam is positioned to contact the rack in a stuck state. A microcontroller is coupled to the sensor and a controller of the liquid handling robot, wherein the microcontroller is configured to monitor the sensor to determine whether the rack is in a stuck state or an unobstructed state in which the light beam is not interrupted by the rack. In response to determining that the rack is in a stuck state, the microcontroller is configured to instruct or signal the liquid handling robot to perform corrective action to disengage the rack from the tip receptacle.

[0005] Implementations of the present disclosure may include one or more of the following optional features. In some implementations, the sensor is an infrared sensor or an ultrasonic sensor. For example, the sensor may include an infrared beam interruption sensor having an emitter configured to emit a light beam and a photoelectric receiver configured to receive the light beam. The microcontroller may be configured to receive an analog or digital signal from the sensor. Furthermore, the microcontroller may interface with an executable script that operates and communicates with a controller of the liquid handling robot.

[0006] In some embodiments, the controller is configured to move the tip receptacle to a check position relative to the light beam so that the microcontroller monitors the sensor and determines whether the rack is in a stuck state or an unblocked state. The microcontroller can monitor the sensor for a selected number of iterations while the tip receptacle remains in the check position. In some examples, the workstation has an opening exposing the cavity, wherein the sensor is positioned such that the light beam extends through the opening, allowing the arm to at least partially lower a plurality of pipette tips into the cavity to determine whether the rack is in a stuck state.

[0007] The rack holding the set of pipette tips engaged by the tip receptacle can be disposed in a stack of racks. In some examples, the workbench has a location defining a loading area that holds the stack of racks, wherein the rack with the set of pipette tips can be disposed on top of the stack of racks in an original position. The corrective action can include returning the rack to the loading area. For example, the corrective action can include disengaging the set of pipette tips from the tip receptacle, reengaging the set of pipette tips with the tip receptacle, and raising the tip receptacle again to remove the reengaged set of pipette tips from the rack.

[0008] Another aspect of the present disclosure provides a liquid handling robot system comprising a frame disposed at a workbench and a liquid testing assembly disposed in a home position at the workbench. The liquid testing assembly comprises a first component and a second component engaged with the first component, wherein the liquid testing assembly is disposed in the home position at the workbench. A liquid handling robot is operably coupled to the frame and comprises a controller and an arm operable to move relative to the workbench in response to commands from the controller. The arm comprises an engagement device configured to engage the first component of the liquid testing assembly. The controller is configured to control the engagement device to engage the first component in the home position and to control the arm to move the engaged first component away from the home position. A sensor is configured to emit a field and sense an interruption in the field. The sensor is coupled to the frame, the workbench, or the arm of the liquid handling robot and is positioned to sense the presence of the second component when the wall remains engaged with the first component after the arm has moved the first component away from the home position. A microcontroller is coupled to the sensor and the controller of the liquid handling robot. The microcontroller is configured to monitor the sensor to determine an error state when the second component is sensed to be engaged with the first component or a clear state where the second component is not sensed. In response to determining the error condition, the microcontroller is configured to instruct the liquid handling robot to iteratively perform a corrective action to disengage the second component from the first component for the lesser of a set number of iterations or until the microcontroller determines an unblocked condition. In some examples, the first component is a filter tube and the second component is a centrifuge tube. In other examples, the first component is a pipette tip and the second component is a rack.

[0009] This aspect may include one or more of the following optional features. In some embodiments, the corrective action provides for disengaging the first component, reengaging the first component, and instructing the microcontroller to check whether the error state still exists. The set number of iterations may be less than 10, such as 5. In order to determine whether an error state, such as a stuck state, exists, the microcontroller may perform several checks, such as a first measurement sequence in which the arm holds the first component in a first position relative to the sensor for a set period of time, and a second measurement sequence in which the arm holds the first component in a second position relative to the sensor for a set period of time. The microcontroller may monitor the sensor for the first measurement sequence and the second measurement sequence, and determine the error state if the second component is sensed in the first measurement sequence or the second measurement sequence. For example, when the microcontroller receives a signal from the sensor that is below a threshold, the signal indicates that the second component is erroneously engaged to the first component to provide an error state.

[0010] In some embodiments, the sensor includes an infrared sensor, an ultrasonic sensor, an inductive sensor, or a capacitive sensor. The sensor may, for example, include an emitter configured to emit a light beam and a photoelectric receiver configured to receive the light beam. The emitter is configured to be positioned so that the light beam is adjacent to the first component when the first component is engaged with the bonding head and is interrupted by the second component when the first component is engaged with the second component. In some examples, the sensor is fixed relative to the frame, wherein the arm moves the first component engaged with the bonding device to a check position, wherein the light beam is arranged to contact the second component in the error state. When determining whether the second component is in the error state, the microcontroller can monitor the sensor for a predefined time with the bonding head in the check position.

[0011] Yet another aspect of the present disclosure provides a system having a liquid handling robot having a workbench configured to support a rack holding a group of pipette tips. The liquid handling robot also has an arm operably suspended above the workbench, wherein the arm includes a tip receiver configured to engage the group of pipette tips. The liquid handling robot also includes a controller configured to control the arm to move relative to the workbench to a position above the rack, control the tip receiver to engage the group of pipette tips held in the rack, and raise the tip receiver away from the workbench to remove the engaged group of pipette tips from the rack. The sensor is fixed relative to the workbench and is operable to emit a light beam. The sensor is configured to sense an interruption of the light beam. The microcontroller is coupled to the sensor and a controller of the liquid handling robot such that the microcontroller is configured to: (i) determine when to move the arm to a checking position that positions a light beam in an area between a pair of adjacent pipette tips in the set of pipette tips engaged with the tip receptacle; (ii) monitor the sensor with the arm in the checking position to determine whether a rack interrupts the light beam to indicate a stuck condition of the rack; and (iii) in response to determining that the rack is in the stuck condition, instruct the liquid handling robot to perform a corrective action to disengage the rack from the set of pipette tips.

[0012] In some embodiments, the corrective action includes releasing the set of pipette tips from a tip receptacle above the rack, reengaging the set of pipette tips from the rack with the tip receptacle, and checking whether the error condition persists. The corrective action can include iteratively releasing and reengaging the set of pipette tips with the tip receptacle for a set number of iterations or until the rack is no longer sensed to be in a stuck state, whichever is less. For example, the microcontroller monitors the sensor for a selected number of iterations with the arm in the checking position. When the microcontroller receives a signal from the sensor that is below a threshold, the signal can indicate that the rack is in a stuck state.

[0013] In some embodiments, the sensor comprises an infrared sensor. For example, the sensor is an infrared beam interruption sensor having an emitter configured to emit a light beam and a photoelectric receiver configured to receive the light beam. The workstation may include an opening exposing the cavity, wherein the sensor may be positioned such that the light beam extends through the opening in an unobstructed state. The workstation may also or alternatively include a loading area for holding a stack of racks, wherein the rack having the set of pipette tips is positioned on top of the stack of racks.

[0014] The details of one or more embodiments of the present disclosure are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1A is a side view of an exemplary liquid handling robot.

[0016] Figure 1B yes Figure 1A Upper perspective view of the end portion of the liquid handling robot.

[0017] Figure 2 yes Figure 1A Lower perspective view of a liquid handling robot showing a pipette tip engaged with the robotic arm.

[0018] Figure 3A yes Figure 1A Lower perspective view of a liquid handling robot showing a rack latched onto pipette tips engaged with the robotic arm.

[0019] Figure 3B A side view of a rack stuck on pipette tips, taken from the end of a liquid handling robot.

[0020] Figure 4A and Figure 4B Is set in Figure 1A Upper perspective view of the sensors at the workstation of the liquid handling robot.

[0021] Figure 5A is to hold the engaged pipette tip relative to Figures 4A to 4B Upper perspective view of the robotic arm showing the inspection position of the sensor.

[0022] Figure 5B It is intercepted in alignment with the sensor's transmitted beam Figure 5A A side view of the robotic arm is shown in the inspection position.

[0023] Figure 5C yes Figure 5AAn upper perspective view of the robotic arm shown in an inspection position illustrating a transmitted light beam passing through a pipette tip.

[0024] Figure 6A is an upper perspective view of a rack holding pipette tips engaged with a robotic arm held in an inspection position.

[0025] Figure 6B is intercepted in alignment with the sensor's transmitted beam Figure 6A A side view of the robotic arm is shown in the inspection position.

[0026] Figure 6C yes Figure 6A An upper perspective view of the robotic arm is shown in an inspection position showing a transmitted light beam contacting a shelf.

[0027] Figure 7 is a perspective view of the mounting location of the additional sensor.

[0028] Figure 8 is a schematic diagram of an example microcontroller connected to an infrared sensor.

[0029] Figure 9 is a diagram illustrating exemplary communication layers.

[0030] Figure 10 is a flow chart of an exemplary method for detecting a stuck state of a rack at a robotic arm of a liquid handling robot.

[0031] Like reference numbers in the various drawings indicate like elements. DETAILED DESCRIPTION

[0032] refer to Figure 1A and Figure 1B In some embodiments, the liquid handling robot 10 has a station structure 12 with a work surface 14 that is configured to support integrated and non-integrated devices (e.g., shakers, incubators) and laboratory equipment, such as liquid containers 16, including microplates, deep well plates, tubes, etc. The station structures in other examples can have various sizes and designs to accommodate different types of laboratory tests, capacities, and needs.

[0033] like Figure 1AAs shown, the station structure 12 includes a frame 18 that surrounds the workbench 14 and supports a transparent cover 20 that prevents dust and contaminants from interfering with the workbench 14 and the devices and labware present on the workbench 14. The transparent cover 20 also serves as a safety barrier to prevent injuries during operation. The transparent cover 20 or its front portion can be raised and lowered, such as with the help of a pneumatic cylinder 22, to allow a user to access the workbench 14 and its contents, such as for preparing an experiment before the system is operated. The frame 18 also supports a robotic arm 24 that is suspended above the workbench 14. Figure 1A As shown, the liquid handling robot 10 has a Cartesian actuation assembly 26 that supports an arm 24 and is similarly suspended above the work table 14. The arm 24 is operative to move above the work table 14 in a horizontal plane (xy direction) that is generally parallel to the work table surface, such as via the Cartesian actuation assembly 26. In doing so, the arm 24 is able to operate at a desired position in the station structure 12. The arm 24 is also operative to move vertically (z direction) relative to the work table 14 to position the engagement head 28 of the arm 24 at a desired position. In other embodiments, the robotic arm can be supported and operated by a variety of different structures and mechanisms.

[0034] like Figure 2 As shown, the engagement head 28 of the arm 24 includes a tip receiver 30 configured to engage a set of pipette tips 32. The tip receiver 30 may include a number of mounting ports 34, each of which is configured to engage a pipette tip. The tip receiver 30 has 96 mounting ports 34 to hold 96 pipette tips, such that the arm 24 may be referred to as a multi-channel arm (MCA). However, other embodiments of the arm and tip receiver may have more or fewer ports to hold a corresponding number of pipette tips, such as 8, 16, 48, 64, or 386 tips. Figure 2 As shown, the mounting port 34 has a portion into which the proximal end 32a of the pipette tip 32 is inserted and engaged. The engagement of the pipette tip with the mounting port or other form of tip receiver can produce a releasable friction and / or mechanical engagement. The tip receiver also includes an ejector to disengage the pipette tip from the engagement head, such as after liquid has been transferred to the pipette and a clean pipette tip is needed for further operation.

[0035] Reference again Figure 1A and Figure 1B , a rack 36 holding a set of pipette tips 32 is arranged at an original position in the station structure 12, such as at a desired position on the workbench 14. The racks 36 may be arranged in a rack stack 38, such as Figure 1AAs shown in . The rack 36 accessed by the robotic arm 24 can be set at the top of the rack stack 38 to facilitate access to the pipette tips from the top of the rack in the stack. Each rack in the rack stack 38 can hold a new set of pipette tips. When the pipette tips from the topmost rack engage the arm 24, the (now empty) top rack must be removed by the arm to expose the next rack (holding another set of tips). The empty rack can also be removed with an auxiliary arm or other device, such as during an operation in which the arm unloads the pipette tips. It is also contemplated that other examples may have a mechanism for removing the bottom rack in the stack for access by the arm, such as a shuttle retriever. The location of the rack stack may be referred to as a loading area for loading pipette tips or otherwise engaging pipette tips to the arm.

[0036] The controller 39 of the liquid transport robot 10 ( Figure 9 ) can utilize data processing hardware and memory hardware that communicates with the data processing hardware. The memory hardware stores instructions that, when executed on the data processing hardware, cause the data processing hardware to perform operations of the controller 39. In some embodiments, the robotic arm is connected to an onboard embedded controller 39 that runs appropriate firmware. This unit is capable of processing machine commands. The liquid handling script is written in a client (PC) application 41 that converts the liquid handling script into machine commands. The controller 39 is thereby configured to control the movement of the arm 24 relative to the workbench 14, such that the controller is configured to move the arm 14 to a position above the rack 36. When the arm is in this raised position, the controller can control the liquid handling robot 10 to engage the tip receptacle 30 with the set of pipette tips 32 held in the rack and then raise the tip receptacle away from the original position, such as upwards away from the rack stack, to remove the engaged set of pipette tips from the rack (the rack is now empty). The controller can then control the liquid handling robot to move the engaged set of pipette tips to an operating position, such as a liquid container or other device or laboratory ware on a work surface, to introduce liquid from the liquid container into at least one tip of the set of pipette tips engaged with the tip receiver.

[0037] like Figure 3A and Figure 3B As shown, the set of pipette tips 32 engaged with the tip receiver 30 may frictionally engage or stick to the rack 36 when being removed, which may cause the rack 36 to be held or stuck by the tips 32 in a stuck state. The planar extent of the rack 36 in the stuck state is typically tilted at an angle that is not horizontal or otherwise not aligned with the work surface, such as Figure 3B In the inclined angle, the openings in the rack 36 that hold the pipette tips frictionally engage the side surfaces of the pipette tips.

[0038] The system is provided with a sensor 40, such as at a station structure or an arm of a robot, to detect when a rack 36 is in a stuck state. Figure 4A and Figure 4B As shown, the sensor 40 is coupled to the station structure 12 , and more specifically, the sensor 40 is fixed at the workbench 14 . Figure 4A and Figure 4B The sensor 40 shown is an infrared beam interruption sensor having an emitter 44 configured to emit a light beam 46 and a photoelectric receiver 48 configured to receive the light beam. In other examples, it is contemplated that the sensor may include an ultrasonic sensor, an inductive sensor, a capacitive sensor, or an alternative infrared sensor, such as a passive infrared (PIR) sensor. However, inductive and capacitive sensing may not perform well with specialized polymer pipette tips.

[0039] After the tip receiver 30 engages the set of pipette tips 32 held in the rack 36 and the engaged tips 32 are raised from the home position, the light beam 46 of the sensor 40 is positioned to contact the rack 36 in the engaged state. Figure 8 The microcontroller 49 is shown coupled to the sensor 40 and a controller of the liquid handling robot (such as via a PC in communication with the controller), wherein the microcontroller 49 is configured to monitor the sensor 40 to determine if the rack 36 is in a stuck state ( Figures 6A to 6C ) or an unimpeded state in which the light beam 46 is not interrupted by the rack 36 ( Figures 5A to 5C ). In some embodiments, the controller is configured to move the tip receiver to a check position relative to the light beam so that the microcontroller monitors the sensor and determines whether the rack is in a stuck state or an unblocked state. The microcontroller can monitor the sensor for a selected number of iterations (e.g., a set time period) with the tip receiver maintained in the check position. The microcontroller can be connected to receive a digital or analog signal from the sensor. In the case of digital signal transmission, a threshold check may not be performed when processing the signal. However, in certain embodiments, such as where a transparent rack is used, the analog sensor signal can be checked against a threshold to determine the presence of the rack. The microcontroller can be connected to or otherwise interfaced with a PC, which then converts commands to the onboard controller into machine commands.

[0040] Likewise Figure 4A and Figure 4B As shown, the workbench 14 may include an opening or cutout exposing the cavity 50, and the sensor 40 may be positioned in the opening or cutout so that the light beam 46 extends through the opening in an unobstructed state ( Figures 5A to 5C The arm may lower the plurality of pipette tips at least partially into the cavity to determine whether the rack is in a stuck state or an error state ( Figures 6A to 6C). In doing so, the sensor 40 is placed in a relatively low position that does not interfere with the movement of the arm or the operation on the table. This also provides a dedicated location for detection, where the table cutout and cavity 50 of the liquid handler are used, through which the centrifuge is normally accessed. On each side of the opening or cutout, the transmitter 44 and receiver 48 are placed facing each other, such as Figure 7 As shown, the receiver is mounted between devices mounted on a workbench.

[0041] In response to determining that the rack 36 is in a stuck state, the microcontroller 49 is configured to signal the body handling robot or instruct the liquid handling robot to perform corrective action to disengage the rack 36 from the tip receptacle 30. In this embodiment, the signal or instruction from the microcontroller is in response to a request from the controller. Thus, the operational logic is implemented on the controller of the liquid handler. In the liquid handling script, the arm moves to a check position and a call is made to run or otherwise operate an executable script on a PC that communicates with and interfaces with the microcontroller. While the controller awaits a response from the executable script (and therefore the microprocessor), the microcontroller operates to determine whether the rack is stuck, whether corrective action should be performed, or whether to continue executing the script.

[0042] The corrective action may include returning the rack to the loading area. For example, the corrective action may include releasing or disengaging (such as with an ejector) the group of pipette tips from the tip receiver above the rack and allowing them to enter the rack, reengaging the group of pipette tips with the tip receiver, and raising the tip receiver again to remove the reengaged group of pipette tips from the rack. After the tips are reengaged, the corrective action includes checking whether the stuck or error state still exists. Therefore, the corrective action may include iteratively releasing the group of pipette tips and reengaging the group of pipette tips with the tip receiver for a set number of iterations or until the rack is no longer sensed to be in a stuck state, whichever is less. The set number of iterations may, for example, be less than 10, such as 5.

[0043] like Figure 7 As shown, as with the dedicated position for detection, a cutout of the workbench of the liquid carrier is used, through which the centrifuge is usually reached. On each side of the cutout, a transmitter 44 and a receiver 48 are placed facing each other. Figure 7 A mounting for the receiver 48 is shown.

[0044] The infrared beam interruption sensor uses HD-DS25CM-3MM, and its parameters are as follows:

[0045] ●Sensing distance: about 25cm / 10"

[0046] Power supply voltage: 3.3-5.5VDC

[0047] ●Emitter current consumption: 10mA@3.3V, 20mA@5V

[0048] ●Receiver output current capability: 100mA sink current

[0049] Transmitter / receiver LED angle: 10°

[0050] Response time: <2ms

[0051] Size: 20mm x 10mm x 8mm / 0.8" x 0.4" x 0.3"

[0052] Cable length: 234mm / 9.2"

[0053] Weight (per half): ~3g

[0054] As an interface between the sensor and the computer, a microcontroller of the Arduino UNO SMD REV3 MCU A000073 type was used, which has the following parameters:

[0055] ATmega328P microcontroller with 14 digital I / O pins (6 of which can be used as PWM outputs)

[0056] ●6-channel analog input

[0057] 16MHz quartz crystal

[0058] 1 USB

[0059] 1 power jack (5.5mm / 2.1mm, 7-12V)

[0060] 1 ICSP header

[0061] 1 reset button

[0062] ●Operating voltage: 5V Flash memory: 32KB

[0063] ●Static random access memory: 2K

[0064] ●Electrically erasable read-only memory: 1K

[0065] Dimensions: 68.6 x 53.4 mm

[0066] like Figure 8As can be seen in the figure, the LED is wired to the digital output so that it is on only for the measured duration, rather than constantly. The maximum current draw is specified as 20mA, which is exactly the same as the maximum current draw on the Arduino digital output, both of which are rated for 5V. Measurements show that the LED actually draws about 12mA, so it can be considered safe to power it directly from the digital output for short periods of time. The receiver is an open-collector phototransistor, meaning that when infrared light from the transmitter strikes the sensor, the data pin is grounded. To read the sensor's value, the data pin can be connected to an analog input on a microcontroller.

[0067] like Figure 9 As shown, two layers of software enable communication between the liquid handler software (EVOware) and the sensors. Directly using EVO to process digital or analog signal inputs would require modifying the robot's firmware and writing a driver for EVOware. Instead, to avoid system modifications, EVOware's built-in commands are used to execute a custom client application that communicates with the microcontroller. The microcontroller is responsible for activating the sensors and reading the values. This process is initiated by an EVOware script, which defines digital variables to store the results. The client application is then called with the appropriate parameters using the "Execute Application" command, such as:

[0068] ●Port_Name: The name of the communication port

[0069] ●Command:

[0070] ○0-1023: Threshold

[0071] ○ "View": Starts continuous reading until the debug timeout is reached

[0072] ● timeout: value in seconds

[0073] The above call example means that COM port 1 will be used to start the measurement and wait for a response for 20 seconds. The threshold of 255 is compared with the eight-bit reading of the analog sensor value, and based on the result, the following response is provided to EVOware:

[0074] ●0: The measured value exceeds the threshold

[0075] ●1: The measured value is lower than the threshold

[0076] ●2: The answer received is invalid

[0077] ●3: Invalid number of parameters

[0078] 4: Timeout

[0079] The client application is responsible for communicating with the microcontroller through the serial port, such as Figure 8As shown in the figure, Microsoft Visual Studio 2019 Community Edition was used as the integrated development environment (IDE), and the application was written in C++. To handle communication, an Arduino-specific serial communication library was used, which uses the Device Control Block (DCB) structure.

[0080] The program first checks and parses the parameters, then waits for a connection until a timeout is reached, in which case it exits with an error. If the connection is successfully established, the command is sent to the microcontroller. The response is processed byte by byte and terminated when a newline character is received. The message is interpreted, and the program returns the appropriate value.

[0081] As the deepest layer of the detection system, the microcontroller program waits for bytes on the serial port and reads them until a newline character is received. If the incoming command is a valid number, it is interpreted as a threshold value, and normal measurement mode is initiated. In this mode, 200 measurements are performed over two seconds, and the average is calculated to minimize the effects of noise. The result is compared with the threshold value, and the appropriate response is written to the serial port. On the other hand, the review mode allows the user to determine the appropriate threshold value by viewing the measured values ​​in various situations. In some applications, such as when semi-transparent objects must be detected, a different threshold value may be required than for completely opaque objects.

[0082] like Figure 10 In the illustrated example, a method for operating a liquid handling robot system provides for first moving an arm of the liquid handling robot relative to a workbench using commands (such as machine commands) transmitted from a controller of the liquid handling robot, as shown in step 52. At step 54, in response to the commands from the controller, a group of pipette tips held in a rack disposed on the workbench is engaged with a tip receptacle disposed at the lower portion of the arm. In response to further commands from the controller, at step 56, the tip receptacle is raised away from the workbench to attempt to remove the group of pipette tips from the rack. The tip receptacle is then moved, along with the arm, to an inspection position at step 58. Next, at step 60, (while the tip receptacle is still in the inspection position) an infrared sensor is used to emit a light beam in an area between a pair of adjacent pipette tips in the group of pipette tips engaged with the tip receptacle. The sensor is then monitored by a microcontroller at step 62 to determine if the light beam is interrupted, indicating that the rack is in a stuck state on the group of pipette tips. In response to determining that the rack is in a stuck condition, at step 64 , a signal is returned from the microcontroller to the controller instructing the liquid handling robot to perform corrective action to disengage the rack from the stuck condition on the set of tip receptacles.

[0083] In another embodiment of a liquid handling robotic system, a liquid testing assembly is provided having a filter tube and a centrifuge tube engaged with the filter tube. The filter tube is removed from the centrifuge tube and can be set in an original position at a workbench. The arm includes an engagement device configured to engage the filter tube of the liquid testing assembly and move the engaged filter tube away from the original position. The sensor is configured to transmit a field and sense an interruption of the field. The sensor is positioned to sense the presence of the filter tube after the arm moves the filter tube away from the original position. The microcontroller is configured to monitor the sensor to determine an error state when the filter tube is not sensed. In response to the determined error state, the liquid handling robot is programmed to iteratively perform corrective actions to engage the filter tube for the lesser of a set number of iterations or until the microcontroller determines a desired state.

[0084] For purposes of this disclosure, the term "coupled" (in all its forms: coupled, coupled, coupled, etc.) generally means the joining of two components directly or indirectly to one another. Unless otherwise specified, such joining may be fixed in nature or movable in nature; may be achieved by integrally forming the two components and any additional intermediate members as a single unitary body with one another or with the two components; and may be permanent in nature or removable or releasable in nature.

[0085] Also for the purposes of this disclosure, the terms "upper," "lower," "right," "left," "rear," "front," "vertical," "horizontal," and their derivatives shall relate to the orientation shown in FIG1 . However, it shall be understood that various alternative orientations may be provided unless expressly specified to the contrary. It shall also be understood that the specific devices and processes shown in the accompanying drawings and described in this specification are merely exemplary embodiments of the inventive concepts defined in the appended claims. Accordingly, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered limiting, unless the claims expressly state otherwise.

[0086] A number of embodiments have been described. However, it will be appreciated that various modifications can be made without departing from the spirit and scope of the present disclosure. Furthermore, other embodiments are within the scope of the following claims.

Claims

1. A liquid handling robot system comprising: a station structure having a work table configured to support a liquid container; a rack configured to hold a group of pipette tips in an original position relative to the station structure, the rack being arranged in a rack stack; a liquid handling robot coupled to the station structure and comprising an arm suspended above the workbench and a controller configured to control movement of the arm relative to the workbench, the arm comprising a tip receptacle configured to engage a set of pipette tips from a rack; wherein the controller is configured to move the arm to a position above the rack, engage the tip receptacle with the set of pipette tips held in the rack, raise the tip receptacle away from the home position to remove the engaged set of pipette tips from the rack, and move the engaged set of pipette tips to the liquid container to introduce liquid from the liquid container into at least one tip of the set of pipette tips engaged with the tip receptacle; a sensor configured to emit a light beam and sense an interruption of the light beam, the sensor coupled to the station structure or the arm of the liquid handling robot; wherein after the tip receptacle engages the set of pipette tips held in the rack and the engaged tips are raised from the home position, the light beam is positioned to contact the rack in a locked state in which the rack frictionally engages the set of pipette tips engaged with the tip receptacle; as well as a microcontroller coupled to the sensor and the controller of the liquid handling robot, the microcontroller being configured to: monitoring the sensor to determine whether the shelf is in the stuck state or in an unobstructed state in which the light beam is not interrupted by the shelf, and In response to determining that the rack is in the stuck state, the liquid handling robot is signaled to perform corrective action to disengage the rack from the tip receptacle.

2. The liquid handling robotic system of claim 1 , wherein the sensor comprises an infrared beam interruption sensor having an emitter configured to emit the light beam and a photoelectric receiver configured to receive the light beam.

3. The liquid handling robotic system of claim 1 , wherein when the microcontroller receives a signal from the sensor that is above a threshold, the microcontroller determines that the light beam is not interrupted by the rack.

4. A liquid handling robot system according to claim 3, wherein the threshold is configured to allow the light beam to pass through (i) an open space between the group of engaged pipette tips or (ii) a translucent portion of the group of engaged pipette tips.

5. The liquid handling robotic system of claim 1 , wherein the controller is configured to move the tip receiver to a checking position relative to the light beam so that the microcontroller monitors the sensor and determines whether the rack is in the stuck state or the unblocked state.

6. The liquid handling robotic system of claim 5, wherein the microcontroller monitors the sensor for a selected number of iterations with the tip receiver maintained in the inspection position.

7. A liquid handling robotic system according to claim 1, wherein the workbench includes a position defining a loading area, the loading area holds the rack stack, and the rack with the set of pipette tips is set on top of the rack stack in the original position.

8. The liquid handling robotic system of claim 7, wherein the work platform includes an opening exposing a cavity, the sensor being positioned such that the light beam extends through the opening in the unobstructed state.

9. The liquid handling robotic system of claim 7, wherein the corrective action comprises returning the rack to the loading area.

10. The liquid handling robotic system of claim 1 , wherein the corrective action comprises disengaging the set of pipette tips from the tip receiver, reengaging the set of pipette tips with the tip receiver, and raising the tip receiver away from the original position to remove the reengaged set of pipette tips from the rack.

11. The liquid handling robotic system of claim 1 , wherein the sensor comprises at least one of an infrared sensor or an ultrasonic sensor.

12. The liquid handling robotic system of claim 1, wherein the rack frictionally engages a side surface of at least one of the set of pipette tips in the captured state.

13. The liquid handling robotic system of claim 1, wherein the microcontroller receives an analog signal from the sensor.

14. The liquid handling robotic system of claim 1, wherein the microcontroller is configured to interface with an executable script that operates and communicates with the controller of the liquid handling robot.

15. A liquid handling robot system comprising: a frame, which is provided at the workbench; a liquid testing assembly comprising a pipette tip and a rack engaged with the pipette tip, the liquid testing assembly being disposed in a home position at the workstation; a liquid handling robot operably coupled to the frame and comprising a controller and an arm operable to move relative to the workstation in response to commands from the controller, the arm including an engagement device configured to engage the pipette tip of the liquid testing assembly; wherein the controller is configured to control the engagement device to engage the pipette tip at the home position and control the arm to move the engaged pipette tip away from the home position; a sensor configured to transmit a field and sense an interruption of the field, the sensor coupled to the frame, the stage, or the arm of the liquid handling robot and positioned to sense the presence of the rack while the rack remains engaged with the pipette tips after the arm moves the pipette tips away from the home position; as well as a microcontroller coupled to the sensor and the controller of the liquid handling robot, the microcontroller configured to monitor the sensor to determine an error condition when sensing engagement of the rack with the pipette tips or a clear condition when the rack is not sensed, and, in response to a determined error condition, instruct the liquid handling robot to iteratively perform a corrective action to disengage the rack from the pipette tips for the lesser of a set number of iterations or until the microcontroller determines a clear condition.

16. The liquid handling robotic system of claim 15, wherein the corrective action comprises disengaging the pipette tip, reengaging the pipette tip, and instructing the microcontroller to check whether the error condition still exists. The liquid handling robotic system of claim 16 , wherein the set number of iterations is less than 10.

18. A liquid handling robot system according to claim 15, wherein, in order to determine an error state, the microcontroller performs: a first measurement sequence, in which the arm maintains the pipette tip in a first position relative to the sensor for a set time period; and a second measurement sequence, in which the arm maintains the pipette tip in a second position relative to the sensor for a set time period.

19. The liquid handling robotic system of claim 18, wherein the microcontroller monitors the sensor for both the first measurement sequence and the second measurement sequence and determines an error condition if the rack is sensed in either the first measurement sequence or the second measurement sequence.

20. The liquid handling robotic system of claim 15, wherein when the microcontroller receives a signal from the sensor that is below a threshold, the signal indicates that the rack is incorrectly engaged to the pipette tip.

21. The liquid handling robotic system of claim 15, wherein when the microcontroller receives a signal from the sensor that exceeds a threshold, the signal indicates that the pipette tip is not engaged to the rack.

22. The liquid handling robotic system of claim 15, wherein the sensor comprises at least one of an infrared sensor, an ultrasonic sensor, an inductive sensor, or a capacitive sensor.

23. The liquid handling robot system of claim 15, wherein the frame includes a loading area for the liquid test assembly, the arm accessible to the loading area to engage the pipette tip, and wherein when the microcontroller determines an error condition, the liquid handling robot returns the rack to the loading area.

24. A liquid handling robot system according to claim 15, wherein the sensor includes an emitter configured to emit a light beam and a photoelectric receiver configured to receive the light beam, the emitter being configured to be positioned so that the light beam is adjacent to the pipette tip when the pipette tip is engaged with the engagement head and is interrupted by the rack when the pipette tip is engaged with the rack.

25. The liquid handling robotic system of claim 24, wherein the sensor is fixed relative to the frame, and wherein the arm is configured to move the pipette tip engaged with the engagement device to an inspection position, wherein the light beam is arranged to contact the rack in an error state.

26. The liquid handling robotic system of claim 25, wherein when determining whether the rack is in the error state, the microcontroller is configured to monitor the sensor for a predefined time with the engagement head in the inspection position.

27. A system comprising: A liquid handling robot comprising: a work surface configured to support a rack holding a set of pipette tips; an arm operably suspended above the workstation, the arm having a tip receptacle configured to engage the set of pipette tips; and a controller configured to control movement of the arm relative to the worktable to a position above the rack, control the tip receptacle to engage the set of pipette tips held in the rack, and raise the tip receptacle away from the worktable to remove the engaged set of pipette tips from the rack; a sensor fixed relative to the table and operable to emit a light beam, the sensor being configured to sense an interruption of the light beam; and a microcontroller coupled to the sensor and the controller of the liquid handling robot, the microcontroller being configured to: determining when to move the arm to an inspection position that positions the light beam in an area between a pair of adjacent pipette tips in the set of pipette tips engaged with the tip receptacle; monitoring the sensor with the arm in the inspection position to determine if the rack interrupts the light beam to indicate a stuck condition of the rack; and In response to determining that the rack is in the stuck state, the liquid handling robot is instructed to perform a corrective action to disengage the rack from the group of pipette tips.

28. The system of claim 27, wherein the corrective action comprises releasing the set of pipette tips from the tip receptacle above the rack, reengaging the set of pipette tips from the rack with the tip receptacle, and checking whether a stuck condition still exists.

29. The system of claim 27, wherein the corrective action comprises iteratively releasing and reengaging the set of pipette tips with the tip receiver for the lesser of a set number of iterations or until the rack is no longer sensed to be in a stuck state.

30. The system of claim 27, wherein when the microcontroller receives a signal from the sensor that is below a threshold, the signal indicates that the rack is engaged in a stuck state.

31. The system of claim 27, wherein the sensor comprises an infrared sensor or an ultrasonic sensor.

32. The system of claim 27, wherein the sensor comprises an infrared beam interruption sensor having an emitter configured to emit the light beam and a photoelectric receiver configured to receive the light beam.

33. The system of claim 32, wherein the stage includes an opening exposing a cavity, the sensor being positioned such that the light beam extends through the opening in an unobstructed state.

34. The system of claim 27, wherein the microcontroller monitors the sensor for a selected number of iterations with the arm in the inspection position.

35. The system of claim 27, wherein the workstation includes a loading area that holds a stack of racks, the rack with the set of pipette tips being positioned on top of the stack of racks.

36. A method comprising: moving an arm of the liquid handling robot relative to the workbench using commands transmitted from a controller of the liquid handling robot; engaging a group of pipette tips held in a rack provided on the workbench with a tip receptacle at a lower portion of the arm in response to a command from the controller; in response to a command from the controller, raising the tip receptacle away from the workstation to attempt to remove the group of pipette tips from the rack; moving the tip receiver together with the arm to an inspection position in response to a command from the controller; emitting a light beam with an infrared sensor in an area between a pair of adjacent pipette tips in the set of pipette tips engaged with the tip receptacle in the inspection position; monitoring the sensor with a microcontroller to determine if the light beam is interrupted to indicate that the rack is in a stuck state on the set of pipette tips; as well as In response to determining that the rack is in the stuck state, a signal is returned from the microcontroller to the controller, the signal instructing the liquid handling robot to perform corrective action to disengage the rack from the set of pipette tips.

37. The method of claim 36, wherein the corrective action comprises releasing the set of pipette tips from the tip receptacle above the rack, reengaging the set of pipette tips from the rack with the tip receptacle, and checking whether a stuck condition still exists.

38. The method of claim 36, wherein the corrective action comprises iteratively releasing and reengaging the set of pipette tips with the tip receiver for the lesser of a set number of iterations or until the rack is no longer sensed to be in a stuck state.

39. The method of claim 36, wherein when the microcontroller receives a signal from the sensor that is below a threshold, the signal indicates that the rack is engaged in the stuck state.

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