Spring-loaded lead screw positioning system

Abstract

A shuttle positioning apparatus includes a lead screw extending along an axis. A shuttle is configured to travel along the axis. A nut is threadedly engaged with the lead screw and mounted within the shuttle. A first spring and a second spring are disposed on opposite sides of the nut along the axis. The first spring and the second spring are configured to bias the nut within the shuttle. A hard stop is positioned along the axis for positioning the shuttle. A sensor is configured to detect when a predetermined pre-load is reached on at least one of the first spring and the second spring.

Description

Docket No. 0082-0034PCT2SPRTNG-LOADED LEAD SCREW POSITIONING SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 749,228, titled "ROBOTIC LAB WARE MODULE FOR A PIPETTE SYSTEM”, filed January 24, 2025, which is hereby incorporated by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] The present disclosure relates to positioning systems for robotic equipment handling modules, and more particularly to a spring-loaded lead screw positioning system that eliminates the need for calibration by driving a carriage against a hard stop and using spring-biased preloading to maintain accurate and repeatable positioning.BACKGROUND

[0003] Robotic systems used in laboratory environments, such as liquid handling systems and pipette systems, often incorporate linear motion components to position equipment and consumables with precision. These systems may include carriages or platforms that travel along one or more axes to deliver labware, such as tip racks, plates, and reservoirs, to designated locations within an enclosure where robotic elements can interact with the equipment.

[0004] Linear motion in such systems is commonly achieved through lead screw mechanisms, where rotation of a threaded lead screw causes a corresponding nut to translate along the screw's axis. The nut may be coupled to a carriage or platform that carries the equipment being positioned. While lead screw systems provide a straightforward approach to linear actuation, achieving accurate and repeatable positioning can present challenges.

[0005] One approach to positioning involves the use of stepper motors that drive the lead screw a calculated number of steps to reach a target position. However, without feedback from encoders or other position sensors, accumulated errors from factors such as missed steps, mechanical compliance, and thermal expansion can result in positioning inaccuracies over time. Linear encoders can provide position feedback but add cost and complexity to the system.

[0006] When auxiliary modules or devices are added to existing robotic systems, calibration procedures are typically performed to establish the spatial relationship between the new equipment and the base system. Such calibration may involve probing the position of the new device, handteaching the robot to recognize equipment locations, or applying factory-determined offsets. TheseDocket No. G082-0034PCT2calibration procedures can be time-consuming and may introduce errors if performed incorrectly, potentially leading to collisions or failed operations during automated runs.

[0007] Anti-backlash mechanisms have been developed to address play or looseness in lead screw and nut assemblies. These mechanisms may employ preloaded nuts, split nuts with spring loading, or other configurations to maintain contact between the nut threads and lead screw threads in a manner that reduces or eliminates backlash. While such mechanisms address thread engagement, they do not inherently solve the challenge of achieving accurate positioning relative to external reference points or eliminating the need for calibration when integrating equipment with robotic systems.

[0008] In applications where a carriage travels to specific fixed locations rather than arbitrary positions throughout a range of motion, alternative approaches to positioning may be beneficial. Hard stops or mechanical references can provide repeatable positioning when a carriage is driven into contact with a fixed surface. However, continuously driving a motor against a hard stop can cause motor stalling, excessive wear, and potential damage to mechanical components.

[0009] Accordingly, there remains an opportunity for positioning systems that can achieve accurate and repeatable carriage placement at fixed locations while avoiding the drawbacks associated with motor stalling and the need for calibration procedures when equipment is installed or integrated with robotic systems.BRIEF DESCRIPTION OF FIGURES

[0010] Non-limiting and non-exhaustive examples are described with reference to the following figures.

[0011] FIG. 1 illustrates a shuttle positioning apparatus, according to at least one example.

[0012] FIG. 2 illustrates the shuttle positioning apparatus of FIG. 1 in a second position, according to at least one example.

[0013] FIG. 3 illustrates the shuttle positioning apparatus of FIG. 1 in a third position, according to at least one example.

[0014] FIG. 4 illustrates a portion of a positioning system including a shuttle and a linear positioner component, according to at least one example.

[0015] FIG. 5 illustrates a section view of a shuttle positioning system in a first position, according to at least one example.Docket No. G082-0034PCT2

[0016] FIG. 6 illustrates a section view of the shuttle positioning system of FIG. 5 in a second position, according to at least one example.

[0017] FIG. 7 illustrates a section view of the shuttle positioning system of FIG. 5 in a third position, according to at least one example.

[0018] FIG. 8 illustrates a section view of a shuttle positioning system in a first position, according to at least one example.

[0019] FIG. 9 illustrates a section view of the shuttle positioning system of FIG. 8 in a second position in contact with a hard stop, according to at least one example.

[0020] FIG. 10 illustrates a section view of the shuttle positioning system of FIG. 8 in a third position in contact with a locating stop, according to at least one example.DETAILED DESCRIPTION

[0021] The following description sets forth exemplary aspects of the present disclosure. It should be recognized, however, that such description is not intended as a limitation on the scope of the present disclosure. Rather, the description also encompasses combinations and modifications to those exemplary aspects described herein.

[0022] The present disclosure describes a shuttle positioning apparatus and associated methods for providing accurate and repeatable positioning of equipment without requiring calibration. Equipment handling systems that move equipment or materials from a first position to a second position may benefit from positioning mechanisms that eliminate the need for calibration procedures that are time-consuming and prone to error. The shuttle positioning apparatus described herein addresses these challenges by employing a spring-loaded lead screw positioning system that drives a shuttle against a hard stop and maintains the shuttle at the hard stop through spring force. This approach provides positioning accuracy that is determined by the machined tolerances of the hard stop and associated components, rather than by encoder feedback or manual calibration. The shuttle positioning apparatus may be implemented in various equipment handling applications, including laboratory automation systems, liquid handling systems, and other robotic systems that require repeatable positioning of components or materials.

[0023] A shuttle positioning apparatus according to the present disclosure may comprise a lead screw extending along an axis. The lead screw may be a threaded rod configured to convert rotational motion into linear motion. A shuttle may be configured to travel along the axis, with the shuttle serving as a carriage or platform for transporting equipment or materials between positionsDocket No. 0082-0034PCT2along the axis. A nut may bethreadedly engaged with the lead screw and mounted within the shuttle, such that rotation of the lead screw causes the nut to translate along the axis. The nut may be captured within the shuttle in a manner that allows limited relative movement between the nut and the shuttle along the axis. A first spring and a second spring may be disposed on opposite sides of the nut along the axis, with the first spring and the second spring configured to bias the nut within the shuttle. The springs may be compression springs that exert force on the nut when compressed, thereby transmitting force between the nut and the shuttle.

[0024] The shuttle positioning apparatus may further comprise a hard stop positioned along the axis for positioning the shuttle. The hard stop may be a fixed mechanical surface against which the shuttle contacts when driven to a particular position along the axis. A sensor may be configured to detect when a predetermined pre-load is reached on at least one of the first spring and the second spring. The sensor may detect the pre-load condition by sensing displacement of the nut relative to the shuttle after the shuttle contacts the hard stop. When the shuttle contacts the hard stop and the lead screw continues to rotate, the nut moves relative to the shuttle and compresses at least one of the first spring and the second spring. The sensor detects when the compression reaches a predetermined level corresponding to the predetermined pre-load, indicating that the shuttle is firmly held against the hard stop by spring force.

[0025] In some cases, the sensor may comprise a photo interrupter configured to detect a flag coupled to the nut. The photo interrupter may include a light source and a light detector arranged such that the flag interrupts a light beam when the flag moves into a detection zone. Alternatively, the sensor may comprise other types of non-contact sensors, such as optical sensors, magnetic sensors, or proximity sensors, that detect displacement of the nut relative to the shuttle. Additionally, due to the tolerances of the system and the presence of the hard stop, the positioning of the sensor is not required to be extremely precise or calibrated as it is used primarily to instruct the motor to cease motion and the actual positioning is performed by reaching the hard stop, therefore relatively inexpensive sensor systems may be used that would not otherwise be possible to use for such a precise operation as positioning relative to another system. The flag may be a tab or projection extending from the nut or from a component coupled to the nut. The flag may be configured to trigger the photo interrupter when the nut is displaced by a predetermined distance after the shuttle contacts the hard stop. In some cases, the predetermined distance may beDocket No. 0082-0034PCT2approximately 2 mm, though other distances may be used depending on the spring characteristics and the desired pre-load force.

[0026] The shuttle may define a pocket, and the nut may be captured between the first spring and the second spring within the pocket. The pocket may be a cavity or recess formed within the shuttle that receives the nut and the springs. The pocket may have walls that retain the springs and limit the travel of the nut within the shuttle. A cover plate may be configured to close off the pocket to retain the nut, the first spring, and the second spring therein. The cover plate may be a removable panel that allows access to the pocket for assembly or maintenance. Alternatively, the pocket may be formed by multiple components of the shuttle that are assembled together to capture the nut and springs. The pocket configuration allows the nut to float within the shuttle along the axis while being biased by the springs on opposite sides.

[0027] The shuttle positioning apparatus may further comprise a motor coupled to the lead screw and configured to rotate the lead screw to drive the shuttle along the axis. The motor may comprise a stepper motor, which provides precise rotational control without requiring position feedback. Alternatively, the motor may comprise a servo motor, a DC motor, or other types of rotary actuators. The sensor may be configured to signal the stepper motor to stop rotation when the predetermined pre-load is reached. A motor controller may receive the signal from the sensor and command the motor to cease rotation, thereby maintaining the shuttle against the hard stop with the spring force. The use of the spring-loaded nut arrangement prevents the motor from stalling against the hard stop, which would otherwise cause excessive wear, heat generation, or damage to the motor or mechanical components.

[0028] The shuttle positioning apparatus may further comprise a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop. The first spring may be configured to bias the shuttle against the hard stop when the shuttle is driven in a first direction, and the second spring may be configured to bias the shuttle against the second hard stop when the shuttle is driven in a second direction opposite the first direction. This arrangement allows the shuttle to be accurately positioned at either end of the axis of travel using the same spring-loaded nut mechanism. The first spring and the second spring may each have a spring constant selected as a function of a maximum torque output of a motor coupled to the lead screw such that the springs compress before the motor stalls when the shuttle contacts the hard stop. The spring constants mayDocket No. 0082-0034PCT2be selected to provide sufficient pre-load force to hold the shuttle firmly against the hard stop while ensuring that the springs compress rather than causing the motor to stall.

[0029] A method of positioning a shuttle along an axis according to the present disclosure may comprise rotating a lead screw to drive a shuttle along the axis, wherein a nut is threadedly engaged with the lead screw and mounted within the shuttle, and wherein a first spring and a second spring are disposed on opposite sides of the nut along the axis. The method may further comprise contacting the shuttle against a hard stop positioned along the axis. The method may further comprise continuing to rotate the lead screw after the shuttle contacts the hard stop such that the nut moves relative to the shuttle and compresses at least one of the first spring and the second spring. The method may further comprise detecting, via a sensor, when a predetermined pre-load is reached on the at least one of the first spring and the second spring. The method may further comprise stopping rotation of the lead screw in response to detecting that the predetermined preload is reached.

[0030] In some cases, detecting when the predetermined pre-load is reached may comprise detecting, via a photo interrupter, a flag coupled to the nut. Alternatively, detecting when the predetermined pre-load is reached may comprise detecting, via a non-contact sensor, displacement of the nut relative to the shuttle. The method may further comprise reversing rotation of the lead screw to drive the shuttle away from the hard stop. The method may further comprise contacting the shuttle against a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop. The method may further comprise continuing to rotate the lead screw after the shuttle contacts the second hard stop such that the nut moves relative to the shuttle and compresses the other of the first spring and the second spring. This bidirectional positioning capability allows the shuttle to be accurately positioned at either end of the axis of travel.

[0031] An equipment handling module for providing equipment between a first position and a second position according to the present disclosure may comprise one or more rails extending along an axis of travel. A carriage may be configured to travel along the one or more rails between the first position and the second position. A lateral motion device may extend along the axis of travel, with the lateral motion device comprising a lead screw or other linear drive mechanism. A nut may be engaged with the lateral motion device and mounted within the carriage. A first spring and a second spring may be disposed on opposite sides of the nut along the axis of travel, with the first spring and the second spring configured to bias the nut within the carriage. A first hard stopDocket No. 0082-0034PCT2may be positioned at the first position and a second hard stop may be positioned at the second position along the axis of travel. A sensor may be configured to detect when a predetermined preload is reached on at least one of the first spring and the second spring.

[0032] The carriage of the equipment handling module may be configured to be driven against one of the first hard stop and the second hard stop and held against the one of the first hard stop and the second hard stop by spring force from the at least one of the first spring and the second spring to position the equipment at a repeatable location. The sensor may comprise a photo interrupter configured to detect a flag coupled to the nut, wherein the flag is configured to trigger the photo interrupter when the nut is displaced by a predetermined distance after the carriage contacts the first hard stop or the second hard stop. The first spring may be configured to bias the carriage against the first hard stop when the carriage is driven in a first direction, and the second spring may be configured to bias the carriage against the second hard stop when the carriage is driven in a second direction opposite the first direction. The carriage may define a pocket, and the nut may be captured between the first spring and the second spring within the pocket, with a cover plate configured to close off the pocket to retain the nut, the first spring, and the second spring therein.

[0033] The equipment handling module may further comprise a stepper motor coupled to the lateral motion device and configured to rotate the lateral motion device to drive the carriage along the axis of travel. The sensor may be configured to signal the stepper motor to stop rotation when the predetermined pre-load is reached. The spring-loaded nut arrangement within the carriage allows the equipment handling module to achieve accurate and repeatable positioning at the first position and the second position without requiring calibration procedures. The tolerance stackup between the hard stops and associated reference surfaces may be controlled to provide positioning accuracy that meets the requirements of the equipment handling application. The equipment handling module may be used in laboratory automation systems, liquid handling systems, or other applications where equipment or materials are transported between defined positions.

[0034] The shuttle positioning system described herein may be implemented in various equipment handling environments and applications. Liquid handling systems, such as pipette systems used in laboratory automation, may incorporate the shuttle positioning system to provide accurate positioning of carriages that transport labware between positions. Laboratory automation equipment that handles labware such as tip racks, PCR plates, deep well plates, and reagentDocket No. 0082-0034PCT2reservoirs may benefit from the shuttle positioning system to achieve repeatable positioning without calibration. Robotic systems that move equipment or materials between defined positions may implement the shuttle positioning system to eliminate calibration procedures that are timeconsuming and prone to error. The shuttle positioning system may be applied to equipment handling modules that interface with liquid handling systems, where the equipment handling module provides labware into an enclosure of the liquid handling system at a repeatable location for interaction by a robot or gripper of the liquid handling system.

[0035] The shuttle positioning system may be applied to X-axis motion for both positive and negative directions along the axis of travel. When the shuttle is driven in a first direction toward a first hard stop at a positive X position, a first spring compresses to bias the shuttle against the first hard stop. When the shuttle is driven in a second direction toward a second hard stop at a negative X position, a second spring compresses to bias the shuttle against the second hard stop. The arrangement of springs on opposite sides of the nut enables the shuttle positioning system to provide spring-biased preloading in both directions of travel along the axis. The shuttle positioning system may also be applied to Z-axis motion for vertical positioning of components within an equipment handling module. On the Z-axis, the shuttle positioning system may use a top spring for the positive Z direction to bias a carriage against a hard stop at the top of the Z-axis travel, while the bottom position may use gravity pulling down to a home position without a spring-loaded mechanism.

[0036] The tolerance stackup between the hard stop and a reference surface, such as a robot's deck, may be configured to be tight enough that the position of the shuttle does not need to be calibrated or communicated to the robot in XYZ space. The positioning accuracy achieved by the shuttle positioning system is determined by the machined tolerances of the hard stop and associated components, providing ultra-repeatable positioning that is as accurate as the machined parts. The shuttle positioning system eliminates the need for calibration when adding an equipment handling module to an existing liquid handler, thereby reducing setup time and avoiding errors that may result from incorrect calibration. The shuttle positioning system may be applied to any moving mechanical component in a similar system that may typically require calibration for accurate positioning, including components that move along linear axes to transport equipment or materials between defined positions.Docket No. 0082-0034PCT2

[0037] The sensor configured to detect when a predetermined pre-load is reached may comprise various types of sensors as alternatives to a photo interrupter. The sensor may comprise a contact sensor positioned at the hard stop to detect when the shuttle contacts the hard stop and the nut is displaced by a predetermined distance. The sensor may comprise a conductive contact or electrical contact that completes a circuit when the flag coupled to the nut moves into contact with the sensor. The sensor may comprise a read switch, such as a reed switch, that detects the presence of a magnet coupled to the nut when the nut is displaced by the predetermined distance. These alternative sensor types would similarly detect when the predetermined pre-load is reached on at least one of the first spring and the second spring, signaling a motor controller to stop rotation of the motor.

[0038] The nut is captured and positioned between two springs within the shuttle, with a plate that retains the springs on opposite sides of the nut. The plate may be a containment wall or cover plate that closes off a pocket within the shuttle to retain the nut, the first spring, and the second spring therein. A flag for the sensor, such as a photo interrupter, is attached to the lead screw nut and moves with the nut when the shuttle contacts the hard stop and the lead screw continues to rotate. The flag moves an additional distance, such as approximately 2 mm, after the shuttle contacts the hard stop, compressing at least one of the springs until the flag triggers the sensor. The presence of two springs, one on either side of the nut, allows for positioning at two different ends of travel using the same positioning system (e.g., a first hard stop at a first end of travel and a second hard stop at a second end of travel). Therefore, in some examples, the system may only include a single spring, for instance if a hard stop were only used for positioning at one position or end of travel. The spring-loaded lead nut mechanism prevents stalling of stepper motors that would otherwise occur from repeatedly driving the shuttle against a hard surface without the spring-loaded arrangement. The shuttle positioning system holds the shuttle in the correct position by having the stepper motor on the lead screw push against spring force from the compressed spring, maintaining the shuttle firmly against the hard stop without stalling the motor or causing excessive wear to the mechanical components.

[0039] Referring to FIGS. 1-3, a shuttle positioning apparatus 100 is illustrated according to at least one embodiment. The shuttle positioning apparatus 100 includes a rail system 102 that supports and guides a shuttle 104 along an axis of travel. Rail system 102 may comprise one or more linear rails, guide rods, or tracks that constrain the movement of the shuttle 104 to a singleDocket No. G082-0034PCT2axis. Alternatively, the rail system 102 may comprise a linear bearing arrangement, a slide mechanism, or other linear guidance systems that provide low-friction support for the shuttle 104 as the shuttle 104 travels along the axis. These alternative rail configurations would similarly support and guide the shuttle 104 along the axis of travel while constraining movement to the desired direction. The shuttle 104 serves as a carriage or platform configured to transport equipment or materials between positions along the axis defined by the rail system 102.

[0040] With continued reference to FIGS. 1-3, a hard stop 106 is positioned along the axis for positioning the shuttle 104 at a repeatable location. The hard stop 106 may be a fixed mechanical surface, such as a machined block or plate, against which the shuttle 104 contacts when driven to a particular position along the axis. The hard stop 106 provides a reference surface that establishes the position of the shuttle 104 with accuracy determined by the machined tolerances of the hard stop 106 and associated components. A lead screw 108 extends along the axis and is coupled to a motor 110 that rotates the lead screw 108 to drive the shuttle 104 along the axis. The lead screw 108 may be a threaded rod configured to convert rotational motion from the motor 110 into linear motion of the shuttle 104. A motor controller 130 is coupled to the motor 110 to control operation of the motor 110, including starting, stopping, and reversing rotation of the lead screw 108.

[0041] As further shown in FIGS. 1-3, a nut 112 may be threadedly engaged with the lead screw 108 and mounted within the shuttle 104. The nut 112 may be captured between a first containment wall 114 and a second containment wall 120 within the shuttle 104. The first containment wall 114 and the second containment wall 120 define boundaries of a pocket or cavity within the shuttle 104 that receives the nut 112 and allows limited relative movement between the nut 112 and the shuttle 104 along the axis. A first spring 116 having a first length 118 may be disposed between the first containment wall 114 and the nut 112. In some embodiments, a second spring 122 having a second length 124 may be disposed between the second containment wall 120 and the nut 112. The presence of two springs, one on either side of the nut, allows for positioning at two different ends of travel using the same positioning system (e.g., a first hard stop at a first end of travel and a second hard stop at a second end of travel). Therefore, in some examples, the system may only include a single spring, for instance if a hard stop were only used for positioning at one position or end of travel. If no second spring 122 is present, the nut 112 may rest against the second containment wall 120. The first spring 116 and the second spring 122 may be compression springs configured to bias the nut 112 within the shuttle 104, with the first length 118 and theDocket No. G082-0034PCT2second length 124 representing the respective lengths of the springs in an uncompressed or partially compressed state.

[0042] With continued reference to FIGS. 1-3, a locating stop 126 is positioned adjacent the hard stop to interface with the nut 112 and the locating stop 126 may include a sensor 128. The locating stop 126 may protrude from the hard stop and may include a sensor to detect a flag, tab, or projection that extends from the nut 112 or from a component coupled to the nut 112. The sensor 128 is configured to detect when a predetermined pre-load is reached on at least one of the first spring 116 and / or the second spring 122. The sensor 128 may comprise a photo interrupter that detects the nut 112 or a flag extending therefrom when the nut 112 reaches the locating stop 126 and moves into a detection zone of the sensor 128. Alternatively, the sensor 128 may comprise other types of non-contact sensors, such as optical sensors, magnetic sensors, or proximity sensors, that detect displacement of the nut 112 or a proximity of a flag connected or coupled to the nut 112. These alternative sensor types may also similarly detect when the predetermined pre-load is reached on at least one of the first spring 116 and the second spring 122.

[0043] As depicted in FIGS. 1-3, when the shuttle 104 contacts the hard stop 106 and the lead screw 108 continues to rotate, the nut 112 moves relative to the shuttle 104 and compresses at least one of the first spring 116 and / or the second spring 122. The locating stop 126 contacts the nut 112 and triggers the sensor 128 when the predetermined pre-load is reached. The sensor 128 signals the motor controller 130 to stop rotation of the motor 110 in response to detecting that the predetermined pre-load is reached. This configuration allows the shuttle 104 to be held against the hard stop 106 by spring force from the compressed spring, providing accurate and repeatable positioning without stalling the motor 110. The spring force maintains the shuttle 104 firmly against the hard stop 106 while the motor 110 remains energized, preventing backlash or movement of the shuttle 104 away from the hard stop 106.

[0044] Referring to FIG. 4, a portion of a positioning system 400 is illustrated according to at least one embodiment. The positioning system 400 includes a shuttle 402 configured to travel along an axis defined by a lead screw 404. The shuttle 402 serves as a carriage or platform for transporting equipment or materials between positions along the axis, similar to the shuttle 104 described with respect to FIGS. 1-3. A nut 406 is threadedly engaged with the lead screw 404 and mounted within the shuttle 402, such that rotation of the lead screw 404 causes the nut 406 to translate along the axis. The nut 406 is captured within the shuttle 402 in a manner that allowsDocket No. G082-0034PCT2limited relative movement between the nut 406 and the shuttle 402 along the axis, enabling the spring-biased preloading mechanism described herein.

[0045] With continued reference to FIG. 4, the positioning system 400 includes a frame 408 that provides structural support for the components of the positioning system 400. The frame 408 may comprise a rigid structure formed from metal, plastic, or other materials that support the lead screw 404, the shuttle 402, and associated components. A frame panel 410 is positioned at one end of the frame 408 along the axis of travel. The frame panel 410 may serve as a mounting surface for components such as a motor that drives the lead screw 404, or the frame panel 410 may provide a reference surface for positioning the shuttle 402 at one end of the axis of travel. The frame 408 and the frame panel 410 together establish the structural foundation for the positioning system 400 and define the boundaries of travel for the shuttle 402 along the axis.

[0046] As further shown in FIG. 4, in some embodiments two springs 412 are disposed on opposite sides of the nut 406 along the axis, with the springs 412 configured to bias the nut 406 within the shuttle 402. The springs 412 may be compression springs that exert force on the nut 406 when compressed, thereby transmitting force between the nut 406 and the shuttle 402. A flag 414 is coupled to the nut 406 and is positioned between the two springs 412. The flag 414 is configured to interact with a sensor to detect when a predetermined pre-load is reached on at least one of the springs 412 as the shuttle 402 is driven against a hard stop. The flag 414 may be a tab or projection extending from the nut 406 that moves with the nut 406 when the shuttle 402 contacts the hard stop and the lead screw 404 continues to rotate. The arrangement of the springs 412 on opposite sides of the nut 406 enables the positioning system 400 to provide spring-biased preloading in both directions of travel along the lead screw 404, allowing the shuttle 402 to be accurately positioned at hard stops located at either end of the axis of travel. In some embodiments, only one spring 412 may be present if the shuttle 402 is required to be accurately positioned at a hard stop located only at one end of the axis of travel.

[0047] Referring to FIGS. 5 and 6, section views of a shuttle positioning system 500 are illustrated according to at least one embodiment, with the shuttle positioning system 500 shown in different configurations. The shuttle positioning system 500 includes a shuttle 502 configured to travel along an axis 508, which is indicated by the dashed line with arrows extending in both directions in the figures. The shuttle 502 serves as a carriage or platform for transporting equipment or materials between positions along the axis 508, similar to the shuttle 104 and the shuttle 402Docket No. 0082-0034PCT2described with respect to FIGS. 1-4. A hard stop 504 is positioned along the axis 508 for positioning the shuttle 502 at a repeatable location. The hard stop 504 may be a fixed mechanical surface against which the shuttle 502 contacts when driven to a particular position along the axis 508, providing a reference surface that establishes the position of the shuttle 502 with accuracy determined by the machined tolerances of the hard stop 504 and associated components.

[0048] With continued reference to FIGS. 5 and 6, a linear positioning system 506 extends along the axis 508 and includes a linear positioner 510 that is engaged with the shuttle 502. The linear positioning system 506 may comprise a lead screw arrangement or other linear drive mechanism configured to convert rotational motion into linear motion of the shuttle 502 along the axis 508. Alternatively, the linear positioning system 506 may comprise a ball screw, a belt drive, or other linear actuation systems that provide controlled movement of the shuttle 502 along the axis 508. These alternative linear positioning configurations would similarly drive the shuttle 502 along the axis 508 while enabling the spring-biased preloading mechanism described herein. The linear positioner 510 may be a nut threadedly engaged with a lead screw of the linear positioning system 506, or the linear positioner 510 may be another type of driven element that translates along the axis 508 in response to actuation of the linear positioning system 506.

[0049] As further shown in FIGS. 5 and 6, the linear positioner 510 is disposed between a first wall 512 and a second wall 514 within the shuttle 502. The first wall 512 and the second wall 514 define boundaries of a pocket or cavity within the shuttle 502 that receives the linear positioner 510 and allows limited relative movement between the linear positioner 510 and the shuttle 502 along the axis 508. A first spring 516 is disposed between the linear positioner 510 and the first wall 512, and a second spring 518 is disposed between the linear positioner 510 and the second wall 514. The first spring 516 and the second spring 518 may be compression springs configured to bias the linear positioner 510 within the shuttle 502, with the springs positioned on opposite sides of the linear positioner 510 along the axis 508. The arrangement of the first spring 516 and the second spring 518 on opposite sides of the linear positioner 510 enables the shuttle positioning system 500 to provide spring-biased preloading in both directions of travel along the axis 508.

[0050] In some examples, the presence of two springs (516, 518), one on either side of the nut, allows for positioning the shuttle at two different ends of travel using the same positioning system (e.g., a first hard stop at a first end of travel and a second hard stop at a second end of travel). Therefore, in some examples, the system may only include a single spring, for instance if a hardDocket No. G082-0034PCT2stop were only used for positioning at one position or end of travel. If, for example, the spring 516 were not present, then the linear positioner may rest against the first wall 512.

[0051] With continued reference to FIGS. 5 and 6, a locating stop 520 is positioned along the axis 508 adjacent to the hard stop 504. The locating stop 520 may serve as a reference point or surface that interacts with components of the shuttle positioning system 500 during positioning operations. A flag 522 is coupled to the linear positioner 510 and extends from the linear positioner 510 in a direction that allows detection by a sensor when the linear positioner 510 is displaced relative to the shuttle 502. The flag 522 may be a tab or projection that moves with the linear positioner 510 when the shuttle 502 contacts the hard stop 504 and the linear positioning system 506 continues to drive the linear positioner 510. The flag 522 is configured to trigger a sensor, such as a photo interrupter, when the linear positioner 510 is displaced by a predetermined distance after the shuttle 502 contacts the hard stop 504.

[0052] FIG. 5 depicts the shuttle positioning system 500 in a first configuration where the shuttle 502 is positioned away from the hard stop 504, with the first spring 516 and the second spring 518 in an uncompressed state. In the first configuration shown in FIG. 5, the linear positioner 510 is centered or neutrally positioned between the first wall 512 and the second wall 514, with the first spring 516 and the second spring 518 exerting balanced biasing forces on the linear positioner 510. The flag 522 extends from the linear positioner 510 in a position that does not trigger a sensor, indicating that the shuttle 502 has not yet contacted the hard stop 504 and the predetermined pre-load has not been reached. The first configuration represents a state of the shuttle positioning system 500 during travel of the shuttle 502 along the axis 508 toward the hard stop 504.

[0053] FIG. 6 depicts the shuttle positioning system 500 in a second configuration where the shuttle 502 has contacted the hard stop 504 and the linear positioner 510 has moved relative to the shuttle 502, compressing the second spring 518 and causing the flag 522 to be displaced. In the second configuration shown in FIG. 6, the shuttle 502 is held against the hard stop 504 by spring force from the compressed second spring 518, with the linear positioner 510 displaced toward the second wall 514 within the shuttle 502. The flag 522 has moved with the linear positioner 510 to a position where the flag 522 can be detected by a sensor, indicating that the predetermined preload has been reached on the second spring 518. The second configuration represents a state of the shuttle positioning system 500 where the shuttle 502 is accurately positioned at the hard stop 504Docket No. G082-0034PCT2and maintained in position by the spring force without stalling a motor of the linear positioning system 506.

[0054] Referring to FIG. 7, a section view of the shuttle positioning system 500 is illustrated showing the internal arrangement of components along the axis 508. FIG. 7 reveals the pocket structure of the shuttle 502 where the linear positioner 510, the first spring 516, and the second spring 518 are retained. The section view shows how the first wall 512 and the second wall 514 define the boundaries of the pocket within the shuttle 502, with the first spring 516 positioned between the first wall 512 and the linear positioner 510, and the second spring 518 positioned between the second wall 514 and the linear positioner 510. The pocket configuration allows the linear positioner 510 to float within the shuttle 502 along the axis 508 while being biased by the first spring 516 and the second spring 518 on opposite sides. The flag 522 is shown coupled to the linear positioner 510 and extending from the linear positioner 510 in a direction that allows detection by a sensor when the linear positioner 510 is displaced relative to the shuttle 502. The locating stop 520 is positioned adjacent to the hard stop 504, and the hard stop 504 provides the reference surface against which the shuttle 502 contacts when driven to the positioned location along the axis 508.

[0055] Referring to FIGS. 8 and 9, section views of a shuttle positioning system 800 are illustrated according to at least one embodiment, with the shuttle positioning system 800 showing a shuttle 802 in different positions along an axis 808. The shuttle 802 is configured to travel along the axis 808, which is indicated by the dashed line with arrows extending in both directions in the figures. The shuttle 802 serves as a carriage or platform for transporting equipment or materials between positions along the axis 808, similar to the shuttle 104, the shuttle 402, and the shuttle 502 described with respect to FIGS. 1-7. A hard stop 804 is positioned along the axis 808 for positioning the shuttle 802 at a repeatable location. The hard stop 804 may be a fixed mechanical surface against which the shuttle 802 contacts when driven to a particular position along the axis 808, providing a reference surface that establishes the position of the shuttle 802 with accuracy determined by the machined tolerances of the hard stop 804 and associated components.

[0056] With continued reference to FIGS. 8 and 9, a linear positioning system 806 extends along the axis 808 and includes a linear positioner 810 that is engaged with the shuttle 802. The linear positioning system 806 may comprise a lead screw arrangement or other linear drive mechanism configured to convert rotational motion into linear motion of the shuttle 802 along theDocket No. G082-0034PCT2axis 808. Alternatively, the linear positioning system 806 may comprise a ball screw, a belt drive, or other linear actuation systems that provide controlled movement of the shuttle 802 along the axis 808. These alternative linear positioning configurations would similarly drive the shuttle 802 along the axis 808 while enabling the spring-biased preloading mechanism described herein. The linear positioner 810 may be a nut threadedly engaged with a lead screw of the linear positioning system 806, or the linear positioner 810 may be another type of driven element that translates along the axis 808 in response to actuation of the linear positioning system 806.

[0057] As further shown in FIGS. 8 and 9, the linear positioner 810 is disposed between a first wall 812 and a second wall 814 within the shuttle 802. The first wall 812 and the second wall 814 define boundaries of a pocket or cavity within the shuttle 802 that receives the linear positioner 810 and allows limited relative movement between the linear positioner 810 and the shuttle 802 alongtheaxis 808. Afirst spring 816 is positioned between the linear positioner 810 and the second wall 814, and a second spring 818 is positioned between the linear positioner 810 and the first wall 812. The first spring 816 and the second spring 818 may be compression springs configured to bias the linear positioner 810 within the shuttle 802, with the springs positioned on opposite sides of the linear positioner 810 along the axis 808. The arrangement of the first spring 816 and the second spring 818 on opposite sides of the linear positioner 810 enables the shuttle positioning system 800 to provide spring-biased preloading in both directions of travel along the axis 808.

[0058] In some examples, the presence of two springs (816, 818), one on either side of the nut, allows for positioning the shuttle at two different ends of travel using the same positioning system (e g., a first hard stop at a first end of travel and a second hard stop at a second end of travel). Therefore, in some examples, the system may only include a single spring, for instance if a hard stop were only used for positioning at one position or end of travel. If, for example, the spring 816 were not present, then the linear positioner may rest against the first wall 812.

[0059] With continued reference to FIGS. 8 and 9, a flag 820 is coupled to the linear positioner 810 and extends toward a sensor 822. The flag 820 may be a tab or projection that moves with the linear positioner 810 when the shuttle 802 contacts the hard stop 804 and the linear positioning system 806 continues to drive the linear positioner 810. The sensor 822 is configured to detect the flag 820 when a predetermined pre-load is reached on at least one of the first spring 816 and the second spring 818. The sensor 822 may comprise a photo interrupter that detects the flag 820 when the flag 820 moves into a detection zone of the sensor 822. Alternatively, the sensor 822 mayDocket No. G082-0034PCT2comprise other types of non-contact sensors, such as optical sensors, magnetic sensors, or proximity sensors, that detect displacement of the linear positioner 810 relative to the shuttle 802. These alternative sensor types would similarly detect when the predetermined pre-load is reached on at least one of the first spring 816 and the second spring 818.

[0060] FIG. 8 depicts the shuttle positioning system 800 with the shuttle 802 in a first position along the axis 808. In the first position shown in FIG. 8, the shuttle 802 is positioned away from the hard stop 804, with the first spring 816 and the second spring 818 in an uncompressed or partially compressed state. The linear positioner 810 is centered or neutrally positioned between the first wall 812 and the second wall 814, with the first spring 816 and the second spring 818 exerting balanced biasing forces on the linear positioner 810. The flag 820 extends from the linear positioner 810 in a position that does not trigger the sensor 822, indicating that the shuttle 802 has not yet contacted the hard stop 804 and the predetermined pre-load has not been reached. The first position represents a state of the shuttle positioning system 800 during travel of the shuttle 802 along the axis 808 toward the hard stop 804.

[0061] FIG. 9 depicts the shuttle positioning system 800 with the shuttle 802 in contact with the hard stop 804. In the configuration shown in FIG. 9, the shuttle 802 has contacted the hard stop 804 and the linear positioner 810 has moved relative to the shuttle 802, compressing the first spring 816. The shuttle 802 is held against the hard stop 804 by spring force from the compressed first spring 816, with the linear positioner 810 displaced toward the second wall 814 within the shuttle 802. The flag 820 has moved with the linear positioner 810 to a position where the flag 820 can be detected by the sensor 822, indicating that the predetermined pre-load has been reached on the first spring 816. The configuration shown in FIG. 9 represents a state of the shuttle positioning system 800 where the shuttle 802 is accurately positioned at the hard stop 804 and maintained in position by the spring force without stalling a motor of the linear positioning system 806.

[0062] Referring to FIG. 10, a section view of the shuttle positioning system 800 is illustrated showing the complete internal arrangement of components along the axis 808 with the sensor 822 positioned to detect the flag 820. FIG. 10 reveals the pocket structure of the shuttle 802 where the linear positioner 810, the first spring 816, and the second spring 818 are retained. The section view shows how the first wall 812 and the second wall 814 define the boundaries of the pocket within the shuttle 802, with the first spring 816 positioned between the linear positioner 810 and the second wall 814, and the second spring 818 positioned between the linear positioner 810 and theDocket No. 0082-0034PCT2first wall 812. The sensor 822 is positioned adjacent to the shuttle 802 to detect the flag 820 when the linear positioner 810 is displaced relative to the shuttle 802 by the predetermined distance. When the sensor 822 detects the flag 820, the sensor 822 signals cessation of movement by communicating with a motor controller to stop rotation of a motor driving the linear positioning system 806, thereby maintaining the shuttle 802 against the hard stop 804 with the spring force from the compressed first spring 816 or the second spring 818.

[0063] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.EXAMPLE CLAUSES

[0064] A. A shuttle positioning apparatus comprising: a lead screw extending along an axis; a shuttle configured to travel along the axis; a nut threadedly engaged with the lead screw and mounted within the shuttle; a first spring and a second spring disposed on opposite sides of the nut along the axis, the first spring and the second spring configured to bias the nut within the shuttle; a set of walls extending from the shuttle to contain the first spring and the second spring in contact with the nut; a hard stop positioned along the axis for positioning the shuttle; and a sensor configured to detect when a predetermined pre-load is reached on at least one of the first spring and the second spring.

[0065] B The shuttle positioning apparatus of paragraph A, wherein the sensor includes a photo interrupter configured to detect a flag coupled to the nut.

[0066] C. The shuttle positioning apparatus of paragraph B, wherein the flag is configured to trigger the photo interrupter when the nut is displaced by a predetermined distance after the shuttle contacts the hard stop.

[0067] D The shuttle positioning apparatus of any of paragraphs A-C, wherein the sensor includes a contact sensor configured to trigger in response to contact with a flag coupled to the nut.

[0068] E. The shuttle positioning apparatus of any of paragraphs A-D, wherein the shuttle defines a pocket, and wherein the nut is captured between the first spring and the second spring within the pocket.

[0069] F. The shuttle positioning apparatus of paragraph E, further comprising a cover plate configured to close off the pocket to retain the nut, the first spring, and the second spring therein.Docket No. 0082-0034PCT2

[0070] G. The shuttle positioning apparatus of any of paragraphs A-F, further comprising a motor coupled to the lead screw and configured to rotate the lead screw to drive the shuttle along the axis.

[0071] H. The shuttle positioning apparatus of paragraph G, wherein the motor includes a stepper motor, and wherein the sensor is configured to signal the stepper motor to stop rotation when the predetermined pre-load is reached.

[0072] I. The shuttle positioning apparatus of any of paragraphs A-H, further comprising a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop, wherein the first spring is configured to bias the shuttle against the hard stop and the second spring is configured to bias the shuttle against the second hard stop.

[0073] J. The shuttle positioning apparatus of any of paragraphs A-I, wherein the first spring and the second spring each have a spring constant selected as a function of a maximum torque output of a motor coupled to the lead screw such that the first spring or the second spring compress before the motor stalls when the shuttle contacts the hard stop.

[0074] K. A method of positioning a shuttle along an axis, the method comprising steps of: rotating a lead screw to drive a shuttle along the axis, a nut being threadedly engaged with the lead screw and mounted within the shuttle, and a first spring and a second spring being disposed on opposite sides of the nut along the axis; contacting the shuttle against a hard stop positioned along the axis; continuing to rotate the lead screw after the shuttle contacts the hard stop such that the nut moves relative to the shuttle and compresses the first spring; and detecting, via a sensor, when a predetermined pre-load is reached on the first spring.

[0075] L. The method of paragraph K, further comprising a step of stopping rotation of the lead screw in response to detecting that the predetermined pre-load is reached.

[0076] M. The method of paragraph L, wherein the step of detecting when the predetermined pre-load is reached includes detecting, via a photo interrupter, a flag coupled to the nut.

[0077] N. The method of any of paragraphs K-M, wherein the step of detecting when the predetermined pre-load is reached includes detecting, via a non-contact sensor, displacement of the nut relative to the shuttle

[0078] O. The method of any of paragraphs K-N, further comprising: reversing rotation of the lead screw to drive the shuttle away from the hard stop; contacting the shuttle against a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop; andDocket No. 0082-0034PCT2continuing to rotate the lead screw after the shuttle contacts the second hard stop such that the nut moves relative to the shuttle and compresses the second spring.

[0079] P. An equipment handling module for providing equipment between a first position and a second position, the equipment handling module comprising: one or more rails extending along an axis of travel; a carriage configured to travel along the one or more rails between the first position and the second position; a lateral motion device extending along the axis of travel; a nut engaged with the lateral motion device and mounted within the carriage; a first spring and a second spring disposed on opposite sides of the nut along the axis of travel, the first spring and the second spring configured to bias the nut within the carriage; a first hard stop positioned at the first position and a second hard stop positioned at the second position along the axis of travel; and a sensor configured to detect when a predetermined pre-load is reached on at least one of the first spring and the second spring, wherein the carriage is configured to be driven against one of the first hard stop and the second hard stop and held against the one of the first hard stop and the second hard stop by spring force from the at least one of the first spring and the second spring to position the equipment at a repeatable location.

[0080] Q. The equipment handling module of paragraph P, wherein the sensor includes a photo interrupter configured to detect a flag coupled to the nut, and wherein the flag is configured to trigger the photo interrupter when the nut is displaced by a predetermined distance after the carriage contacts the first hard stop or the second hard stop.

[0081] R. The equipment handling module of paragraph P or Q, wherein the first spring is configured to bias the carriage against the first hard stop when the carriage is driven in a first direction and the second spring is configured to bias the carriage against the second hard stop when the carriage is driven in a second direction opposite the first direction.

[0082] S. The equipment handling module of any of paragraphs P-R, wherein the carriage defines a pocket, and wherein the nut is captured between the first spring and the second spring within the pocket, the equipment handling module further comprising a cover plate configured to close off the pocket to retain the nut, the first spring, and the second spring therein.

[0083] T. The equipment handling module of any of paragraphs P-S, further comprising a stepper motor coupled to the lateral motion device and configured to rotate the lateral motion device to drive the carriage along the axis of travel, wherein the sensor is configured to signal the stepper motor to stop rotation when the predetermined pre-load is reached.Docket No. 0082-0034PCT2

[0084] U. A shuttle positioning apparatus, comprising: a lead screw extending along an axis; a shuttle configured to travel along the axis; a nut threadedly engaged with the lead screw and mounted within the shuttle; a spring disposed on one side of the nut along the axis, the spring configured to bias the nut against a wall of the shuttle; a hard stop positioned along the axis for positioning the shuttle; and a sensor configured to detect when a predetermined pre-load is reached on the spring.

[0085] V. The shuttle positioning apparatus of paragraph U, further comprising a second spring disposed on an opposite side of the nut from the spring along the axis, the second spring configured to bias the nut within the shuttle.

[0086] W. The shuttle positioning apparatus of paragraph V, further comprising a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop, wherein the spring is configured to bias the shuttle against the hard stop and the second spring is configured to bias the shuttle against the second hard stop.

[0087] X. The shuttle positioning apparatus of any of paragraphs U-W, wherein the sensor comprises a photo interrupter configured to detect a flag coupled to the nut.

[0088] Y. The shuttle positioning apparatus of paragraph X, wherein the flag is configured to trigger the photo interrupter when the nut is displaced by a predetermined distance after the shuttle contacts the hard stop.

[0089] Z. The shuttle positioning apparatus of any of paragraphs U-Y, further comprising a motor coupled to the lead screw and configured to rotate the lead screw to drive the shuttle along the axis.

[0090] AA. The shuttle positioning apparatus of paragraph Z, wherein the motor comprises a stepper motor, and wherein the sensor is configured to signal the stepper motor to stop rotation when the predetermined pre-load is reached.

[0091] AB. The shuttle positioning apparatus of any of paragraphs U-AA, wherein the spring has a spring constant selected as a function of a maximum torque output of a motor coupled to the lead screw such that the spring compresses before the motor stalls when the shuttle contacts the hard stop.

[0092] AC. A method of positioning a shuttle along an axis, the method comprising: rotating a lead screw to drive a shuttle along the axis, wherein a nut is threadedly engaged with the lead screw and mounted within the shuttle, and wherein a spring is disposed on one side of the nut alongDocket No. 0082-0034PCT2the axis; contacting the shuttle against a hard stop positioned along the axis; continuing to rotate the lead screw after the shuttle contacts the hard stop such that the nut moves relative to the shuttle and compresses the spring; and detecting, via a sensor, when a predetermined pre-load is reached on the spring.

[0093] AD. The method of paragraph AC, further comprising: reversing rotation of the lead screw to drive the shuttle away from the hard stop; contacting the shuttle against a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop, wherein a second spring is disposed on an opposite side of the nut from the spring along the axis; and continuing to rotate the lead screw after the shuttle contacts the second hard stop such that the nut moves relative to the shuttle and compresses the second spring until a second sensor detects a second predetermine pre-load is reached on the second spring.

Claims

Docket No. 0082-0034PCT2CLAIMS1. A shuttle positioning apparatus comprising:a lead screw extending along an axis;a shuttle configured to travel along the axis;a nut threadedly engaged with the lead screw and mounted within the shuttle;a first spring and a second spring disposed on opposite sides of the nut along the axis, the first spring and the second spring configured to bias the nut within the shuttle;a set of walls extending from the shuttle to contain the first spring and the second spring in contact with the nuta hard stop positioned along the axis for positioning the shuttle; anda sensor configured to detect when a predetermined pre-load is reached on at least one of the first spring and the second spring.

2. The shuttle positioning apparatus of claim 1, wherein the sensor includes a photo interrupter configured to detect a flag coupled to the nut.

3. The shuttle positioning apparatus of claim 2, wherein the flag is configured to trigger the photo interrupter when the nut is displaced by a predetermined distance after the shuttle contacts the hard stop.

4. The shuttle positioning apparatus of claim 1, wherein the sensor includes a contact sensor configured to trigger in response to contact with a flag coupled to the nut.

5. The shuttle positioning apparatus of claim 1, wherein the shuttle defines a pocket, and wherein the nut is captured between the first spring and the second spring within the pocket.

6. The shuttle positioning apparatus of claim 5, further comprising a cover plate configured to close off the pocket to retain the nut, the first spring, and the second spring therein.

7. The shuttle positioning apparatus of claim 1, further comprising a motor coupled to the lead screw and configured to rotate the lead screw to drive the shuttle along the axis.Docket No. 0082-0034PCT28. The shuttle positioning apparatus of claim 7, wherein the motor includes a stepper motor, andwherein the sensor is configured to signal the stepper motor to stop rotation when the predetermined pre-load is reached.

9. The shuttle positioning apparatus of claim 1, further comprising a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop,wherein the first spring is configured to bias the shuttle against the hard stop and the second spring is configured to bias the shuttle against the second hard stop.

10. The shuttle positioning apparatus of claim 1 , wherein the first spring and the second spring each have a spring constant selected as a function of a maximum torque output of a motor coupled to the lead screw such that the first spring or the second spring compress before the motor stalls when the shuttle contacts the hard stop.

11. A method of positioning a shuttle along an axis, the method comprising steps of: rotating a lead screw to drive a shuttle along the axis, a nut being threadedly engaged with the lead screw and mounted within the shuttle, and a first spring and a second spring being disposed on opposite sides of the nut along the axis;contacting the shuttle against a hard stop positioned along the axis;continuing to rotate the lead screw after the shuttle contacts the hard stop such that the nut moves relative to the shuttle and compresses the first spring; anddetecting, via a sensor, when a predetermined pre-load is reached on the first spring.

12. The method of claim 11, further comprising a step of stopping rotation of the lead screw in response to detecting that the predetermined pre-load is reached.

13. The method of claim 12, wherein the step of detecting when the predetermined preload is reached includes detecting, via a photo interrupter, a flag coupled to the nut.Docket No. 0082-0034PCT214. The method of claim 11 , wherein the step of detecting when the predetermined preload is reached includes detecting, via a non-contact sensor, displacement of the nut relative to the shuttle.

15. The method of claim 11, further comprising:reversing rotation of the lead screw to drive the shuttle away from the hard stop; contacting the shuttle against a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop; andcontinuing to rotate the lead screw after the shuttle contacts the second hard stop such that the nut moves relative to the shuttle and compresses the second spring.

16. An equipment handling module for providing equipment between a first position and a second position, the equipment handling module comprising:one or more rails extending along an axis of travel;a carriage configured to travel along the one or more rails between the first position and the second position;a lateral motion device extending along the axis of travel;a nut engaged with the lateral motion device and mounted within the carriage;a first spring and a second spring disposed on opposite sides of the nut along the axis of travel, the first spring and the second spring configured to bias the nut within the carriage;a first hard stop positioned at the first position and a second hard stop positioned at the second position along the axis of travel; anda sensor configured to detect when a predetermined pre-load is reached on at least one of the first spring and the second spring,wherein the carriage is configured to be driven against one of the first hard stop and the second hard stop and held against the one of the first hard stop and the second hard stop by spring force from the at least one of the first spring and the second spring to position the equipment at a repeatable location.

17. The equipment handling module of claim 16, wherein the sensor includes a photo interrupter configured to detect a flag coupled to the nut, andDocket No. 0082-0034PCT2wherein the flag is configured to trigger the photo interrupter when the nut is displaced by a predetermined distance after the carriage contacts the first hard stop or the second hard stop.

18. The equipment handling module of claim 16, wherein the first spring is configured to bias the carriage against the first hard stop when the carriage is driven in a first direction and the second spring is configured to bias the carriage against the second hard stop when the carriage is driven in a second direction opposite the first direction.

19. The equipment handling module of claim 16, wherein the carriage defines a pocket, andwherein the nut is captured between the first spring and the second spring within the pocket, the equipment handling module further comprising a cover plate configured to close off the pocket to retain the nut, the first spring, and the second spring therein.

20. The equipment handling module of claim 16, further comprising a stepper motor coupled to the lateral motion device and configured to rotate the lateral motion device to drive the carriage along the axis of travel,wherein the sensor is configured to signal the stepper motor to stop rotation when the predetermined pre-load is reached.

21. A shuttle positioning apparatus, comprising:a lead screw extending along an axis;a shuttle configured to travel along the axis;a nut threadedly engaged with the lead screw and mounted within the shuttle;a spring disposed on one side of the nut along the axis, the spring configured to bias the nut against a wall of the shuttle;a hard stop positioned along the axis for positioning the shuttle; anda sensor configured to detect when a predetermined pre-load is reached on the spring.Docket No. 0082-0034PCT222. The shuttle positioning apparatus of claim 21, further comprising a second spring disposed on an opposite side of the nut from the spring along the axis, the second spring configured to bias the nut within the shuttle.

23. The shuttle positioning apparatus of claim 22, further comprising a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop, wherein the spring is configured to bias the shuttle against the hard stop and the second spring is configured to bias the shuttle against the second hard stop.

24. The shuttle positioning apparatus of claim 21, wherein the sensor comprises a photo interrupter configured to detect a flag coupled to the nut.

25. The shuttle positioning apparatus of claim 24, wherein the flag is configured to trigger the photo interrupter when the nut is displaced by a predetermined distance after the shuttle contacts the hard stop.

26. The shuttle positioning apparatus of claim 21, further comprising a motor coupled to the lead screw and configured to rotate the lead screw to drive the shuttle along the axis.

27. The shuttle positioning apparatus of claim 26, wherein the motor comprises a stepper motor, and wherein the sensor is configured to signal the stepper motor to stop rotation when the predetermined pre-load is reached.

28. The shuttle positioning apparatus of claim 21, wherein the spring has a spring constant selected as a function of a maximum torque output of a motor coupled to the lead screw such that the spring compresses before the motor stalls when the shuttle contacts the hard stop.

29. A method of positioning a shuttle along an axis, the method comprising:rotating a lead screw to drive a shuttle along the axis, wherein a nut is threadedly engaged with the lead screw and mounted within the shuttle, and wherein a spring is disposed on one side of the nut along the axis;Docket No. 0082-0034PCT2contacting the shuttle against a hard stop positioned along the axis;continuing to rotate the lead screw after the shuttle contacts the hard stop such that the nut moves relative to the shuttle and compresses the spring; anddetecting, via a sensor, when a predetermined pre-load is reached on the spring.

30. The method of claim 29, further comprising:reversing rotation of the lead screw to drive the shuttle away from the hard stop; contacting the shuttle against a second hard stop positioned along the axis on an opposite side of the shuttle from the hard stop, wherein a second spring is disposed on an opposite side of the nut from the spring along the axis; andcontinuing to rotate the lead screw after the shuttle contacts the second hard stop such that the nut moves relative to the shuttle and compresses the second spring until a second sensor detects a second predetermine pre-load is reached on the second spring.

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