End effector having pliable bladder with adjustable rigidity

End effectors and a related method of actuating items are disclosed. The end effector comprises a bladder comprising a pliable body that defines an inner recess in fluid communication with the manifold via a first connection. The pliable body has a sealing surface at its distal end and defines a chamber. The bladder further comprises a material disposed within the chamber. The method comprises contacting an item to conform the sealing surface to a contour of the item, transitioning the bladder to a structural state having greater rigidity, applying a vacuum to the inner recess via the first connection, and actuating the item.

BACKGROUND

The present disclosure relates to actuating items using an end effector, and more specifically, to implementations of a suction-based end effector having a pliable bladder with adjustable rigidity.

In warehouse operations and other industrial automation settings, end effectors may be configured to perform the picking and handling of items. For example, end effectors such as suction cups or vacuum cups may be used to suction items as they are being actuated between locations in a warehouse. The performance of suction-based end effectors is largely dependent on the quality of the seal formed with the suctioned item. More specifically, a suctioned item may be dropped by the end effector and/or damaged when inertial forces caused by moving the item overcome the suction force. This result is more likely for heavier items, as well as for complex-shaped items for which forming a higher-quality seal may be difficult.

Further, the design of an end effector may be optimized for picking and handling a particular type of item, or for items with one or more characteristics such as dimensions or weights. Thus, performance can be affected when the end effector is required to handle various types of items.

DETAILED DESCRIPTION

While conventional suction-based end effectors may be effective at actuating items having planar surfaces, actuating items that have no planar surfaces represents a technical challenge. The end effectors described herein include a bladder with a pliable body that is able to rigidly conform to a contour of the item to be suctioned. As a result, the end effector forms and maintains an improved seal with the item, enabling items with complex shapes to be manipulated at greater velocities and/or accelerations without loss of suction. Additionally, because material disposed within the pliable body is used to conform the pliable body to the contour of the item, any contact force that might be required to conform the pliable body to the contour is minimal, diminishing a likelihood of damage to the item.

According to one or more embodiments described herein, an end effector that is configured to actuate irregularly shaped items is disclosed. The end effector comprises a manifold and a bladder attached to the manifold. The bladder comprises a pliable body that defines an inner recess in fluid communication with the manifold via a first connection. The pliable body has a sealing surface at its distal end and an opening at its proximal end that is in fluid communication with the manifold via a second connection. The pliable body further defines a chamber. A material is disposed in the chamber. The end effector further comprises a first vacuum port in fluid communication with the first connection. The end effector further comprises a signaling port that communicates a signal to the bladder causing the bladder to transition from a first structural state to a second structural state that is more rigid than the first structural state.

In some embodiments, communicating the signal to the bladder causes a change to a composition of the material and/or a change of state of the material. In some embodiments, the material comprises a fluid and the signaling port comprises a second vacuum port. The change to the composition of the material may comprise evacuating at least part of the fluid from the chamber via the second vacuum port. In some embodiments, the material further comprises a granular material, and evacuating at least part of the fluid from the chamber causes a jamming of the granular material.

FIGS. 1A and 1Bare diagrams100,120of an exemplary end effector105, according to various embodiments. More specifically, the diagram100represents an exterior view of the end effector105, and the diagram120represents a cross-sectional view of the end effector105. The end effector105may be used within an industrial automation system or any alternate environment suitable for handling items.

The end effector105comprises a bladder110connected with a manifold115. The bladder110comprises a pliable body125(or “body”) made of any suitable pliable material(s). Some non-limiting examples of pliable materials include elastomeric materials such as latex, rubber, and silicone. The pliable body125comprises an inner surface130defining a region135(also referred to as an “inner recess”, a “central region”, or a “vacuum region”). The pliable body125may be configured to entirely circumscribe the region135. In some embodiments, the inner surface130and/or the region135are elliptical, such as an ellipse or a circle. When viewed from a top view, the manifold115and the bladder110have elliptical shapes that are concentric and coextensive. However, other suitable shapes, sizes, and/or non-concentric arrangements of the manifold115and the bladder110are also possible.

The pliable body125further comprises a sealing surface140at a distal end of the pliable body125. The sealing surface140defines an opening145to the region135. In some embodiments, bringing an item into contact with the sealing surface140causes the sealing surface140to conform to a contour of the item and thereby seals the region135from ambient.

The end effector105comprises a plurality of ports. A vacuum port150is in fluid communication with the region135and is configured to pull a vacuum in the region135when sealed by the sealing surface140. A signaling port155is in communication with the bladder110and is configured to communicate signals to the bladder110to control a rigidity thereof. In some embodiments, the signals cause the bladder110to transition between a first structural state to a second structural state that is more rigid than the first structural state. As discussed herein, the terms “first structural state” and “second structural state” may refer to any of the bladder110and the pliable body125.

The bladder110may be in the first structural state (i.e., less rigid) to allow the sealing surface140to conform to the item to be suctioned to the end effector105. The bladder110may transition to the second structural state (i.e., more rigid) to maintain the bladder110in the conformed state, e.g., before and/or while the item is suctioned to the end effector105. In this way, the bladder110may be maintained in the conformed state while the item is being moved, allowing the end effector105to maintain an improved seal with the item. As a result, heavier items and/or complex-shaped items may be manipulated by the end effector105at greater velocities and/or accelerations without loss of suction.

In some embodiments, the pliable body125defines a chamber that is partly or completely filled with a material. In some cases, the material in the chamber comprises a composition of a plurality of materials in any suitable phase(s): solid(s), liquid(s), and/or gas(es). Communicating the signals to the bladder110via the signaling port155causes one or more of: a change to a composition of the material and a change of state of the material.

In some embodiments, the chamber of the bladder110is partially filled with a solid and partially filled with a fluid. In such embodiments, the signaling port155may be a vacuum port that is configured to evacuate at least part of the fluid from the chamber to increase a rigidity of the bladder110. In this way, evacuating at least part of the fluid acts to change the material composition in the chamber. In one non-limiting example, the solid in the chamber comprises a granular material, and the fluid comprises air. Evacuating at least part of the air from the chamber may cause a jamming of the granular material, which increases a rigidity of the bladder110. The inventors surmise that evacuating at least part of the air from the chamber increases friction between particles of the granular material, thus making the granular material as a whole more rigid. In another non-limiting example, the solid in the chamber comprises a compressible material such as a gel or foam.

Other types of materials suitable for selectively increasing a rigidity of the bladder110are also contemplated. In one non-limiting example, the chamber comprises a smart fluid, such as a magnetorheological (MR) fluid, a ferrofluid, or an electrorheological (ER) fluid that is configured to change its viscosity. The MR fluid and ferrofluid are generally configured to change viscosity responsive to a magnetic field intensity. In such a case, the signaling port155may communicate the signals to one or more electromagnets disposed proximate to the chamber to change the magnetic field intensity. The ER fluid is generally configured to change viscosity responsive to an electric field intensity.

In some embodiments, the suction (or astrictive force) provided via the vacuum port150provides substantially all of the force binding the item to the end effector105. Stated another way, in some embodiments, the amount of impactive gripping force applied by the pliable body125(or bladder) on the item in the second structural state is minimized. For example, when the item is suctioned to the end effector105, the sealing surface140may contact a single side of the item and the pliable body125provides no compressive (or squeezing) force on the item. In another example, the sealing surface140may contact different sides of the item, but any force provided by the pliable body125(such as a frictional force) is negligible relative to the suction provided via the vacuum port150. In one embodiment, the force provided by the pliable body125may be considered negligible when it is 5% or less of the amount of the applied suction force.

The manifold115may represent a continuously rigid portion of the end effector105, and may be used to interface with other components of the industrial automation system. For example, one or more mechanical arms for spatially manipulating the end effector105(e.g., displacing and/or rotating) may be attached to the manifold115. In another example, the manifold115may provide points of attachment to the end effector105, e.g., such as attaching a hose to the vacuum port150and/or attaching a cable, hose, etc. to the signaling port155.

Therefore, in some embodiments, the manifold115has a greater rigidity than the pliable body125when in the first structural state. The manifold115may also have a greater rigidity than the pliable body125when in the second structural state, but this is not a requirement. The manifold115may be formed of any suitable material(s), which may include relatively inelastic material(s) such as plastics or metals. However, in some cases, the manifold115may be formed of elastic material(s) and dimensioned to provide a greater rigidity than the pliable body125in the first structural state. In one non-limiting example, the manifold115may be formed of a same elastomeric material as the pliable body125, but has a much greater thickness than walls of the pliable body125.

The manifold115and the bladder110may be connected through any suitable means. In some embodiments, the manifold115and the bladder110are removably connected using threaded fasteners. In other embodiments, the manifold115and the bladder110are integrally formed.

FIGS. 2A and 2Billustrate handling an item using an end effector, according to various embodiments. The features illustrated inFIGS. 2A and 2Bmay be used in conjunction with other embodiments, such as the end effector105ofFIG. 1.

The diagram200comprises a controller205that is configured to interface with the end effector105through at least the vacuum port150and the signaling port155. In some embodiments, the controller205is further configured to interface with the end effector105through one or more actuators235connected thereto. The one or more actuators235may have any suitable form, and may control the end effector105according to one or more degrees of freedom. Some non-limiting examples of the one or more actuators235comprise articulating and/or telescoping robotic arms.

The controller205comprises one or more computer processors206and a memory208. The one or more computer processors206represent any number of processing elements that each can include any number of processing cores. Some non-limiting examples of the one or more computer processors206include a microprocessor, a digital signal processor (DSP), an application-specific integrated chip (ASIC), and a field programmable gate array (FPGA), or combinations thereof. The memory208may comprise volatile memory elements (such as random access memory), non-volatile memory elements (such as solid-state, magnetic, optical, or Flash-based storage), and combinations thereof. Moreover, the memory208may be distributed across different mediums (e.g., network storage or external hard drives).

The memory208may comprise a plurality of “modules” for performing various functions described herein. In one embodiment, each module includes program code that is executable by one or more of the computer processors206. However, other embodiments may include modules that are partially or fully implemented in hardware (i.e., circuitry) or firmware of the controller205.

In some embodiments, the memory208may comprise item information associated with the different items in the environment, which may include destination information210associated with the items. The destination information210may have any suitable form, such as a destination within the warehouse (e.g., a particular container or a particular environment location), a destination external to the warehouse (e.g., a portion of a destination mailing address or a particular vehicle for external transport), and so forth. In some embodiments, the controller205acquires the destination information210from one or more computing devices that are networked with the controller205.

Although not shown, the controller205may be communicatively coupled with one or more sensors in the environment. In one non-limiting example, the controller205acquires imagery using one or more visual sensors. The one or more computer processors206may process the imagery to locate and/or identify the item215, and/or to determine a positioning and/or orientation of the end effector105relative to the item215.

In some embodiments, the controller205is configured to transmit control signals to the one or more actuators235to provide the end effector105with a desired positioning and/or orientation for contacting and/or handling the item215. In the diagram200, the end effector105has been brought into contact with the item215resting on a surface220. The controller205may further transmit control signals to the one or more actuators to displace the end effector105and the suctioned item215to a predefined location, which in some cases may be specified by the destination information210. In some alternate embodiments, the end effector105and/or the item215may be manually moved to provide the contacting relationship, and/or to displace the end effector and the suctioned item215to the predefined location. For example, the end effector105may include a handle allowing a user to rotate and/or displace the end effector105.

In some embodiments, the controller205is configured to transmit control signals to a vacuum source230to selectively pull a vacuum on the vacuum region of the end effector105. The vacuum source230may have any suitable implementation, such as a vacuum pump connected to the vacuum port150via a flexible hose. Pulling the vacuum on the vacuum region operates to suction the item215to the end effector105. In some embodiments, the controller205transmits control signals to the vacuum source230to release the vacuum when the item215is at the predefined location.

The controller205is further configured to transmit control signals to a state-change source225to control a rigidity of a bladder of the end effector105. In one non-limiting example, the state-change source225comprises a second vacuum source and the signaling port155comprises a second vacuum port in fluid communication with the bladder. In another non-limiting example, the state-change source225comprises one or more electromagnets configured to generate a magnetic field across the bladder with a desired intensity.

Next, method300ofFIG. 3will be described with reference toFIGS. 2A and 2B. The method300begins at block305, where an item215is contacted with a sealing surface at a distal end of a pliable body of a bladder, to conform the sealing surface to a contour of the item215while the bladder is in a first structural state. In some cases, conforming the sealing surface to the contour of the item215seals an inner recess of the pliable body from ambient. In some embodiments, the controller205communicates signals to the one or more actuators235to move the end effector105to contact the item215.

At block315, the controller205communicates a signal to the vacuum source230to apply a vacuum to an inner recess via a first connection. The inner recess is defined by the pliable body. In some cases, applying the vacuum the first vacuum port150to suction the item215to the bladder. At block325, the controller205communicates a signal to the bladder causing the bladder to transition from the first structural state to a second structural state that is more rigid than the first structural state. In some embodiments, the signal is provided to a state-change source225(e.g., a second vacuum pump, one or more electromagnets) that is communicatively coupled with the bladder via the signaling port155. In some embodiments, transitioning the bladder to the second structural state occurs while the item215is suctioned to the bladder. In other embodiments, transitioning the bladder to the second structural state occurs before the item215is suctioned to the bladder.

At block335, the controller205communicates a signal to one or more actuators235to actuate the item215. In some cases, actuating the item215comprises displacing the end effector105and the item215suctioned to the bladder. By increasing the rigidity of the bladder, the bladder is maintained in the conformed state and provides an improved seal with the item215while the item215is being actuated. The improved seal may allow heavier items and complex-shaped items to be manipulated at greater velocities and/or accelerations without loss of suction.

At block345, the controller205communicates a signal to the vacuum source230to release the vacuum on the inner recess to release the item215at a predefined location. In some embodiments, the predefined location corresponds to destination information210associated with the item215. For example, the destination information210may indicate that the item215is destined for a container245. Responsive to determining that the end effector105has moved the item215to a position above the container245, the controller205causes the vacuum to be released, which causes the item215to be released into the container245.

At block355, the controller205communicates a signal to the bladder causing the bladder to transition out of the second structural state. In some embodiments, a rigidity of the bladder may be decreased responsive to the signal. For example, the bladder may be returned into the first structural state, such that the end effector105is ready to contact and/or handle another item. In some embodiments, transitioning the bladder out of the second structural state occurs after the vacuum on the central region has been released. In other embodiments, transitioning the bladder out of the second structural state may be at least partly overlapping in time with releasing the vacuum. The method300ends after completion of block355.

FIGS. 4A-4Dare views of an end effector with two vacuum ports, according to various embodiments. More specifically, diagrams400,450represent exterior views of the end effector105, and the diagrams495,496represent exploded views of the end effector105. The features described with respect to diagrams400,450,495,496may be used in conjunction with other embodiments described herein.

The manifold115defines a plurality of openings460-1,460-2from a top surface465thereof. The openings460-1,460-2are dimensioned to receive a respective threaded portion455-1,455-2of a respective vacuum port150,405. The vacuum port405represents one example of the signaling port155described above. The vacuum port150and/or the vacuum port405may be connected to the manifold115in any suitable manner. For example, the vacuum ports150,405may be integrally formed with the manifold115.

The openings460-1,460-2may extend partly or fully through the manifold115, such that the vacuum ports150,405are in fluid communication with respective portions of the bladder110via the openings460-1,460-2. For example, the vacuum port150may be in fluid communication with a central region135defined by the bladder110, and the vacuum port405may be in fluid communication with a chamber485defined by the bladder110.

The bladder110comprises a base portion425and a walled portion430that extends from the base portion425. The base portion425is dimensioned to connect the bladder110with the manifold115. In some embodiments, the base portion425and the walled portion430are separate components that may be connected to each other. For example, the base portion425may define a plurality of grooves497,498each configured to receive part of the walled portion430. The base portion425and the walled portion430may be attached using any suitable means, such as bonded using an adhesive. In other embodiments, the base portion425and the walled portion430may be integrally formed.

The walled portion430comprises an inner wall435that defines the central region135, and an outer wall440disposed around the inner wall435. In some embodiments, the inner wall435is received partly into the groove497, and the outer wall440is received partly into the groove498. Although not shown, the walled portion430may further comprise a surface section extending between the inner wall435and the outer wall440. A rim section445may extend outwardly from the outer wall440. The surface section and the rim section445may provide the sealing surface of the end effector105, which is discussed above with respect toFIG. 1.

Referring now toFIGS. 7A and 7B, diagrams700,710illustrate the chamber485and a vacuum region135of a bladder, according to various embodiments. More specifically, the diagram700provides a top view of the walled portion430in which the inner wall435, the outer wall440and the rim section445each have a circular shape and are concentrically arranged. The diagram710provides a top view of the walled portion430in which the inner wall435, the outer wall440and the rim section445each have an ellipse shape and are concentrically arranged. Notably, the ellipse shapes illustrated in the diagram710may be particularly well-suited for handling elongated items, such as book spines. More specifically, aligning the long axis of an elongated item with the semi-major axis of the ellipse shapes may allow a better seal to be formed and maintained by the end effector105. As a result, less suction force may be required to suction the elongated item to the end effector105, which corresponds to a reduced probability of damage to the elongated item.

As discussed above, in some embodiments, the end effector105may increase a rigidity of the bladder after a vacuum has been pulled on the central region135and the item has already been suctioned to the end effector105. However, in other embodiments, the rigidity of the bladder may be increased after the sealing surface has conformed to a contour of the item and before the vacuum is pulled on the central region135. As mentioned above, this sequence may be particularly beneficial for items that are more susceptible to damage, as a lower amount of suction force may be required to suction the items to the end effector105.

While the diagrams700,710illustrate elliptical shapes such as circles and ellipses, other shapes of the inner wall435, the outer wall440, and/or the rim section445are also possible. Generally, shapes with rounded corners (e.g., oval, stadium, rounded rectangle, rounded hexagon) may be preferable, as non-rounded corners may be more prone to wear for repeated cycling of the pliable bladder. However, shapes with non-rounded corners (e.g., rectangle, triangle, hexagon) are also contemplated. Further, in some cases the inner wall435, the outer wall440, and/or the rim section445may have differing shapes, and/or may have a non-concentric arrangement.

Returning now toFIGS. 4A and 4B, in some embodiments, the base portion425has a greater rigidity than the walled portion430. In one non-limiting example, the base portion425is formed of relatively inelastic material(s) such as plastics or metals, and the walled portion430is formed of an elastomeric material. In another non-limiting example, the base portion425is formed of a same elastomeric material as the walled portion, but has a much greater thickness than an inner wall435and/or an outer wall440of the walled portion430.

A plurality of openings480-1,480-2may extend partly or fully through the base portion425, such that the vacuum port150is in fluid communication with the central region135via the opening480-1, and the vacuum port405is in fluid communication with the chamber485via the opening480-2. As shown, the opening480-1has an elliptical shape and the opening480-2has a annular shape that at least partly circumscribes the opening480-1. The openings480-1,480-2may be concentrically arranged, but this is not a requirement. Further, the openings480-1,480-2may have any alternate shapes, dimensions, and/or arrangements suitable for providing fluid communication through the base portion425to respective portions of the bladder110. For example, one alternate implementation of the base portion425may have an opening480-2that is elliptical and that does not circumscribe the opening480-1.

In some embodiments, a filter475may be disposed between the chamber485and the opening460-2in the manifold115. The filter475is configured to allow certain material to pass therethrough, while retaining other material in the chamber485. In one non-limiting example, the chamber485may be partly filled with a granular material and partly filled with air. The filter475may have a pore size selected such that all (or nearly all) of the granular material is retained in the chamber485, while the air may be evacuated through the filter475.

The filter475is shown as having an annular shape sized to overlap with the opening480-2. The filter475defines an opening476that allows an opening555in the manifold115to remain in fluid communication with an opening480-1of the base portion425. Although not discussed in detail, the filter475may comprise additional openings for receiving fasteners or other features therethrough to provide the filter475with a suitable alignment relative to the manifold115and/or the base member425. However, different sizes and shapes of the filter475are also possible consistent with the configuration of the opening480-2. Further, while the filter475is shown between the manifold115and the base portion425, alternate implementations may include the filter475at a different location that is further upstream (i.e., closer to a vacuum source) or further downstream (i.e., further from the vacuum source). Some examples of upstream positions include within the manifold115, within the vacuum port405, and within a hose connecting the vacuum port405with a vacuum source. Some examples of a downstream position include within the base portion425and within the bladder110.

A gasket470-1may be arranged between the opening480-1and the opening480-2of the base portion425to ensure fluidic isolation between the center region135and the chamber485. Similarly, a gasket470-2may be arranged between the opening480-2and the perimeter of the manifold115to ensure fluidic isolation between the chamber485and ambient. The gaskets470-1,470-2may be made of any suitable material, such as rubber or silicone. In some embodiments, the gaskets470-1,470-2are arranged in grooves530-1,530-2that are formed into the manifold115.

The manifold115comprises a plurality of tabs410-1,410-2,410-3,410-4,410-5,410-6extending from and spaced along a perimeter of the manifold115. Each of the tabs410-1, . . . ,410-6has a respective opening415-1,415-2,415-3,415-4,415-5,415-6extending therethrough. The base portion425comprises a plurality of tabs420-1,420-2,420-3,420-4,420-5,420-6extending from and spaced along a perimeter of the base portion425. Each of the tabs420-1, . . . ,420-6has a respective opening490-1,490-2,490-3,490-4,490-5,490-6extending at least partly therethrough. The openings490-1, . . . ,490-6of the tabs420-1, . . . ,420-6are dimensioned and spaced to register with respective openings415-1, . . . ,415-6of the tabs410-1, . . . ,410-6. In some embodiments, threaded fasteners such as bolts or screws may be inserted through pairs of the registered openings490-1and415-1,490-2and415-2, and so forth to connect the bladder110with the manifold115.

The base portion425includes a same number of the openings490-1, . . . ,490-6as the number of the openings415-1, . . . ,415-6of the manifold115. As shown, the openings of the manifold115correspond to the openings of the base portion425in a 1:1 ratio, although other ratios are possible. In an alternate embodiment, the manifold115and the base portion425may have a different number of openings. Stated another way, the openings of the manifold115may correspond to the openings of the base portion425in another ratio, such as 2:1, 3:2, and so forth.

Further, in alternate implementations, at least one of the base portion425and the manifold115do not include the outwardly-extending tabs. Instead, the corresponding openings for receiving fasteners may be formed at locations within the perimeter of the base portion245and/or the manifold115.

FIGS. 5A and 5Billustrate exemplary structural states of a pliable bladder110, according to various embodiments. More specifically, diagram500illustrates a cross-sectional view of the end effector105in which the bladder110is in a first structural state550, and diagram560illustrates a cross-sectional view of a portion of the end effector105in which the bladder110is in a second structural state565with a greater rigidity than the first structural state. The features described with respect to the diagrams500,560may be used in conjunction with other embodiments described herein.

In the diagram500, the manifold115defines a threaded socket520-1in the opening460-1, and a threaded socket520-2of the opening460-2. The threaded socket520-1is configured to mate with the threaded portion455-1of the vacuum port150, and the threaded socket520-2is configured to mate with the threaded portion455-2of the vacuum port405.

The manifold115further defines a plurality of grooves530-1,530-2configured to receive a respective gasket470-1,470-2. The manifold115further defines a chamber525that is in fluid communication with the vacuum port405and with the chamber485. As shown, the chamber525has a annular shape, but other shapes and sizes of the chamber525are also possible. The manifold115further defines a chamber555that is in fluid communication with the vacuum port150and with the inner recess135through the opening480-1.

The manifold115further defines an opening535configured to receive a fastener. As discussed above, when the manifold115is aligned with the base portion425, the openings490-1,415-2of respective tabs420-1,410-2are registered. In this arrangement, the opening535is registered with an opening540extending through the base portion425. In some embodiments, threaded fasteners such as bolts or screws may be inserted through the registered openings535,540to connect the bladder110with the manifold115.

The bladder110comprises a surface portion515extending between the inner wall435and the outer wall440. The surface portion515and the rim section445may provide the sealing surface140of the end effector105, which is discussed above with respect toFIG. 1.

The chamber485comprises a material composition545, which may include one or more materials in any suitable phase(s)—solid(s), liquid(s), and/or gas(es). As mentioned above with respect toFIG. 1, communicating a signal to the bladder110via the signaling port causes one or more of a change to the material composition545and a change of state of a first material. In the diagram500, the vacuum port405represents one example of the signaling port.

In some embodiments, the chamber485is partially filled with a solid and partially filled with a fluid. In such embodiments, the vacuum port405is configured to evacuate at least part of the fluid from the chamber to increase a rigidity of the bladder110and transition to the second structural state. In this way, evacuating at least part of the fluid acts to change the material composition545in the chamber485.

In one non-limiting example, the solid in the chamber485comprises a granular material, and the fluid comprises air. Evacuating at least part of the air from the chamber485may cause a jamming of the granular material, which increases a rigidity of the bladder110. The granular material may comprise any suitable material(s) having desired sizing and interaction characteristics. In some embodiments, a granule size of the granular material is between about 200 microns and about 2000 microns. Generally, a granular material having relatively low friction interactions may be preferable to one having higher friction interactions, as individual granules of the granular material and/or the surrounding portions of the chamber485(e.g., the inner wall435, the outer wall440, the surface portion515) tend to wear more slowly. Specifically, ideal granular materials have low inter-granule friction in ambient pressure and high inter-granule friction under vacuum pressure. Some non-limiting examples of the granular material include charcoal, activated carbon, salt, sugar, and sand. Further, in some cases, coating layer(s) may be applied to individual granules to provide desired characteristics, such as increased hardness, reduced friction, and so forth. Still further, while the example discusses atmospheric air as the fluid in the chamber485, other types of fluids may also be suitable, such as elemental gases, gas mixtures, and liquids.

In another non-limiting example, the solid in the chamber485comprises a compressible material such as a gel or foam, and evacuating at least part of the fluid causes a compression of the compressible material and an increased rigidity of the bladder110. For example, the compressible material may be a cellular silicone or a silicone gel.

In some embodiments, the bladder110may have a different rigidity at various points between the proximal end and the distal end. In one embodiment, different portions of the chamber485may comprise different material compositions. For example, a first portion of the chamber485near the distal end of the bladder110may comprise a first compressible material that is more pliable to allow the sealing surface140to conform, while a second portion of the chamber comprises a second compressible material that is more rigid. In another embodiment, the inner wall435and/or the outer wall440may be dimensioned differently at various points. For example, the inner wall435may have a smaller thickness near the distal end of the bladder110to be more pliable, and may have a larger thickness away from the distal end to be more rigid.

Next, method800ofFIG. 8will be described with reference toFIGS. 5A and 5B. The method800begins at block805, where an item215contacts with a sealing surface140at a distal end of a pliable body of a bladder110to conform the sealing surface140to a contour of the item215while the bladder is in a first structural state. In some cases, conforming the sealing surface140operates to seal a central region135from ambient. In some embodiments, a controller (e.g., controller205ofFIG. 2) communicates signals to one or more actuators (e.g., actuators235ofFIG. 2) to move the end effector105to contact the item215.

In some embodiments, a diameter d of the opening145is substantially unchanged when the bladder110transitions from the first structural state550to the second structural state565. In some embodiments, the inner wall435is dimensioned (e.g., a thickness) to be sufficiently rigid to maintain the same diameter d at the opening145. In other embodiments, the end effector105further comprises a spring disposed within the central region135, and the spring may provide additional rigidity to maintain the same diameter d at the opening145. The spring is configured to oppose motion into the central region135of the item215seated on the sealing surface140.

At block815, a vacuum is applied to the inner recess135via a first connection. The inner recess135is defined by the pliable body. In some embodiments, a vacuum source pulls the vacuum via the first vacuum port150to suction the item215to the bladder110. At block825, a vacuum is applied to the chamber485via a second connection to increase a rigidity of the bladder110. In some embodiments, a vacuum source pulls the vacuum via the second vacuum port405to evacuate at least part of a fluid partially filing the chamber485and transitioning the pliable body to a structural state having greater rigidity. In some embodiments, rigidity of the bladder110is increased due to jamming of a granular material in the chamber. In some embodiments, transitioning the bladder100to the structural state having greater rigidity occurs while the item215is suctioned to the bladder110. In other embodiments, transitioning the bladder110to the structural state having greater rigidity occurs before the item215is suctioned to the bladder110.

At block835, the item215is actuated. In some embodiments, the controller communicates a signal to one or more actuators to displace the end effector105and the item215suctioned to the bladder110. By increasing the rigidity of the bladder110, the bladder110is maintained in the conformed state and provides an improved seal with the item215while the item215is being displaced. The improved seal may allow heavier items and complex-shaped items to be manipulated at greater velocities and/or accelerations without loss of suction.

Example test results using an implementation of the end effector105are provided in Table 1 below. The values represent an amount of force (e.g., inertial force) required to separate a suctioned item from an end effector. Generally, larger values reflect a higher quality seal by the end effector and an ability to withstand greater inertial forces. Two different items were used: a cube-shaped item having a length of 110 millimeters (mm) and a mass of 3 kilograms (kg), and a cylinder-shaped item having a radius of 75 mm, a length of 80 mm, and a mass of 3 kg. The end effector105has an inner diameter d of 40 millimeters (mm) and an outer diameter of 88 mm. The end effector105was suctioned to a top surface of the cube-shaped item, and to a round surface of the cylinder-shaped item. The results are compared with a conventional foam suction cup having an inner diameter of 55 mm and an outer diameter of 80 mm.

As shown in Table 1, the conventional foam suction cup performs relatively well for the cube-shaped item but not as well for the cylinder-shaped item. The end effector105consistently performs better than the conventional foam suction cup when in the second structural state (i.e., where the bladder110has a greater rigidity).

The end effector105may include other features to increase its ability to withstand greater inertial forces. In some embodiments, one or more portions of the end effector105may perform mechanical damping of the inertial forces. For example, the base portion425or another layer (e.g., between the base portion425and the manifold115) may be dimensioned to provide mechanical damping.

Continuing the method800, at block845, the controller communicates a signal to the vacuum source to release the vacuum on the inner recess135to release the item215at a predefined location. In some embodiments, the predefined location corresponds to destination information (e.g., destination information210ofFIG. 2) associated with the item215.

At block855, the controller communicates a signal to the bladder110to decrease the rigidity of the bladder110. For example, the bladder110may be returned into a structural state in which the end effector105is ready to contact and/or handle another item. In some embodiments, decreasing the rigidity of the pliable body occurs after the vacuum on the central region135has been released. In other embodiments, decreasing the rigidity of the pliable body may be at least partly overlapping in time with releasing the vacuum. The method800ends after completion of block855.

In one alternate embodiment, the chamber485comprises a magnetorheological (MR) fluid that is configured to change its viscosity responsive to magnetic field intensity. Control signals may be provided to one or more electromagnets disposed proximate to the chamber485to change the magnetic field intensity and thus the viscosity of the MR fluid. In some cases, responsive to a change in magnetic field intensity, the MR fluid may be transitioned from a liquid phase in the first structural state550to a viscoelastic solid phase in the second structural state565. In some cases, a volume of the MR fluid in the chamber485may change when transitioning between the first structural state550and the second structural state565. For example, the chamber485may be filled with the MR fluid, and conforming the sealing surface140to the item215causes a portion of the MR fluid to exit the chamber485. In another example, a vacuum source may evacuate a portion of the MR fluid to control a volume of the chamber485. Other types or combinations of materials suitable for selectively increasing a rigidity of the bladder110are also contemplated.

FIG. 6illustrates several embodiments of a pliable bladder. The features described with respect toFIG. 6may be used in conjunction with other embodiments described herein. In diagram600, the surface portion515is substantially perpendicular to the inner wall435and/or the outer wall440, and is substantially flat within a plane605. In diagram610, the surface portion515is curved between the inner wall435and the outer wall440, and the curve extends to the plane605.

In diagram620, the surface portion515is curved along a curve625. In diagram630, the inner wall435and the outer wall440comprise respective bellows sections635-2,635-1that provide flexibility to the inner wall435and the outer wall440. In alternate embodiments, only one of the inner wall435and the outer wall440comprises a bellows section635-2,635-1.

In some embodiments, a reinforcing structure may be disposed within the inner recess135, and the reinforcing structure is configured to oppose motion of the inner wall435into the inner recess135. In some embodiments, the reinforcing structure has an annular shape with a diameter that is approximately the same as the diameter (d) of the inner recess135. The annular shape of the reinforcing structure allows the inner recess135to remain in fluid communication with the vacuum port150via the opening480-1. The reinforcing structure is constructed to be more rigid than the inner wall435, e.g., formed of a rigid plastic or metal, formed of an elastomeric material with a greater thickness than the inner wall435, and so forth. In diagram640, the reinforcing structure comprises a spring645that Sis arranged in the central region135. In some embodiments, the spring645is connected with the base portion of the bladder110and is configured to oppose motion into the central region135of an item seated on the sealing surface. In some embodiments, a diameter of the spring645is approximately the same as the diameter of the central region135. In this configuration, the spring645may provide additional rigidity, e.g., to prevent the inner wall435from deforming into the central region135. In some embodiments, a height of the spring645is approximately the same as a height of the central region135, but this is not a requirement.