U.S. patent application number 11/158604 was filed with the patent office on 2005-10-20 for gripping mechanisms, apparatus, and methods.
This patent application is currently assigned to IRM LLC. Invention is credited to Downs, Robert Charles, Mainquist, James Kevin, Weselak, Mark Richard.
Application Number | 20050232743 11/158604 |
Document ID | / |
Family ID | 25159484 |
Filed Date | 2005-10-20 |
United States Patent
Application |
20050232743 |
Kind Code |
A1 |
Downs, Robert Charles ; et
al. |
October 20, 2005 |
Gripping mechanisms, apparatus, and methods
Abstract
The present invention provides grasping mechanisms, gripper
apparatus/systems, and related methods. Grasping mechanisms that
include stops, support surfaces, and height adjusting surfaces to
determine three translational axis positions of a grasped object
are provided. In addition, grasping mechanisms that are resiliently
coupled to other gripper apparatus components are also
provided.
Inventors: |
Downs, Robert Charles; (La
Jolla, CA) ; Weselak, Mark Richard; (San Diego,
CA) ; Mainquist, James Kevin; (San Diego,
CA) |
Correspondence
Address: |
QUINE INTELLECTUAL PROPERTY LAW GROUP, P.C.
P O BOX 458
ALAMEDA
CA
94501
US
|
Assignee: |
IRM LLC
Hamilton
BM
|
Family ID: |
25159484 |
Appl. No.: |
11/158604 |
Filed: |
June 21, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11158604 |
Jun 21, 2005 |
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10620324 |
Jul 14, 2003 |
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6932557 |
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10620324 |
Jul 14, 2003 |
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PCT/US02/06096 |
Feb 26, 2002 |
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PCT/US02/06096 |
Feb 26, 2002 |
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09793254 |
Feb 26, 2001 |
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6592324 |
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Current U.S.
Class: |
414/741 |
Current CPC
Class: |
B65H 2555/31 20130101;
Y10S 414/141 20130101; B65G 47/90 20130101; B25J 15/0253 20130101;
B25J 17/0208 20130101; B65H 29/02 20130101; Y10S 294/902 20130101;
Y10S 414/136 20130101 |
Class at
Publication: |
414/741 |
International
Class: |
B66C 001/00 |
Claims
1. A grasping mechanism, comprising movably coupled arms that are
structured to grasp an object, wherein the arms are movably coupled
to each other such that the arms can move towards or away from each
other along a first axis, and further wherein the arms are attached
to a body that comprises a resilient coupling which allows the arms
to move in a direction substantially perpendicular to the first
axis.
2. The grasping mechanism of claim 1, wherein the grasping
mechanism is structured to grasp the object between the arms.
3. The grasping mechanism of claim 1, wherein the resilient
coupling allows the arms to move along a y-axis.
4. The grasping mechanism of claim 1, wherein the arms comprise a
polished or coated surface that reduces friction between the object
and the arms, relative to an unpolished or non-coated surface, when
the object is grasped by the arms.
5. The grasping mechanism of claim 1, wherein the arms comprise one
or more rollers that reduce friction between the object and the
grasping mechanism, relative to arms that lack the rollers, when
the object is grasped by the arms.
6. The grasping mechanism of claim 1, further comprising the
object.
7. The grasping mechanism of claim 6, wherein the object is
selected from the group consisting of: a plate, a sample plate, a
micro-well plate, a reaction block, a reaction block carrier, a
sample holder, a petri dish, a test tube, a vial, a crucible, a
reaction vessel, a reaction flask, a semi conductor wafer, a CD,
and a tray.
8. The grasping mechanism of claim 1, wherein at least one arm
comprises a stop.
9. The grasping mechanism of claim 8, wherein the stop is
structured to determine a y-axis position of the object.
10. The grasping mechanism of claim 9, wherein the y-axis position
of the object is determined with an accuracy to within about 0.1
millimeters.
11. The grasping mechanism of claim 1, wherein an interface between
the arms and the body comprises at least one spring, which spring
resiliently couples the arms to the body.
12. The grasping mechanism of claim 11, wherein the interface
comprises a sliding interface.
13. The grasping mechanism of claim 1, wherein one or more of the
arms comprise at least one support surface and/or at least one
height adjusting surface.
14. The grasping mechanism of claim 13, wherein each support
surface is disposed between two height adjusting surfaces, which
height adjusting surfaces are angled to push the object into
contact with the support surface when the object is grasped.
15. The grasping mechanism of claim 13, wherein the support surface
and the height adjusting surface form a channel to grasp the
object.
16. The grasping mechanism of claim 13, wherein the support surface
comprises a substantially horizontal surface to support the object
and the height adjusting surface comprises an angled surface that
intersects with the substantially horizontal surface, which angled
surface pushes the object into contact with the substantially
horizontal surface when the arms grasp the object.
17. The grasping mechanism of claim 13, wherein at least one of the
arms comprise a pivot member, which pivot member comprises the
support surface and the height adjusting surface.
18. The grasping mechanism of claim 17, wherein the pivot member is
resiliently coupled to the arm.
19. The grasping mechanism of claim 18, wherein the arm further
comprises a stop that is resiliently coupled to the arm.
20. The grasping mechanism of claim 13, wherein the support surface
determines an x-axis position of the object and the height
adjusting surface determines a z-axis position of the object when
the arms grasp the object.
21-55. (canceled)
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of International
Patent Application No. PCT/US02/06096, entitled "GRIPPER
MECHANISMS, APPARATUS, AND METHODS," which was filed on Feb. 26,
2002 by Downs et al., which is a continuation-in-part of U.S.
patent application Ser. No. 09/793,254, entitled "GRIPPER
MECHANISM," which was filed on Feb. 26, 2001 by Downs et al., the
disclosures of which are incorporated by reference.
COPYRIGHT NOTIFICATION
[0002] Pursuant to 37 C.F.R. .sctn. 1.71(e), Applicants note that a
portion of this disclosure contains material which is subject to
copyright protection. The copyright owner has no objection to the
facsimile reproduction by anyone of the patent document or patent
disclosure, as it appears in the Patent and Trademark office patent
file or records, but otherwise reserves all copyright right
whatsoever.
FIELD OF THE INVENTION
[0003] The present invention relates to gripping devices and
methods. More specifically, the invention provides robotic
apparatus and related methods to grasp and translocate objects.
BACKGROUND OF THE INVENTION
[0004] Many types of robotic devices have been constructed to
perform tasks considered either too dangerous or monotonous to be
performed by human operators. For example, robots can often perform
certain repetitive tasks that generally lead humans to distraction
and error. However, constructing a robotic system to reliably and
quickly grasp and accurately position objects is not a trivial
task.
[0005] Many industrial fields require the accurate positioning of
an object for automated processing. In particular, the
biotechnology industry is making rapid advances by transitioning
from traditional laboratory bench top processes to more automated
systems. These automated systems typically perform assays or
screens using a sample plate, such as a microwell plate. Each
sample plate typically includes multiple sample wells, generally
ranging from a few to thousands of wells. As discrete tests can be
performed in each sample well, hundreds or thousands of assays can
be performed in each plate.
[0006] For a robotic or other automated system to perform with a
high degree of reproducibility and sufficient throughput, the
system generally needs to accurately, quickly, and reliably
position individual sample plates for analysis or other processing.
For example, sample plates must be accurately placed relative to
liquid dispensers such that sample or reagent aliquots are
deposited into specified wells. A positioning error of only a
fraction of a millimeter can result in a sample being dispensed
into an incorrect well. Such a mistake can lead to biased assay
results which may be relied upon for critical decision making, such
as a course of medical treatment for a patient. In addition,
positioning errors can also cause needles or tips of liquid
dispensers to unintentionally contact walls or other surfaces of a
sample plate with a typical consequence being damage to the liquid
dispenser.
[0007] Conventional automated or robotic devices typically do not
operate with sufficient positioning accuracy, e.g., to reliably and
repeatably position high-density sample plates for high-throughput
processing. Additionally, conventional devices also typically
require one or more re-gripping steps that further limit
throughput. Accordingly, there exists a need for robotic or
otherwise automated gripper apparatus and related methods for
accurately, reliably, and quickly positioning objects such as
sample plates for processing or other manipulation without
intervening re-gripping steps. These and other features of the
present invention will become apparent upon complete review of the
following disclosure.
SUMMARY OF THE INVENTION
[0008] The present invention provides gripper apparatus, grasping
mechanisms, and related methods for accurately grasping and
manipulating objects with higher throughput than preexisting
technologies. In certain embodiments, for example, grasping
mechanisms are resiliently coupled to other gripper apparatus
components. In other embodiments, grasping mechanism arms include
support surfaces and height adjusting surfaces to determine x-axis
and z-axis positions of objects being grasped. In certain other
embodiments of the invention, grasping mechanism arms include pivot
members that align with objects as they are grasped. In some of
these embodiments, pivot members include the support surfaces and
height adjusting surfaces. In other embodiments, the arms of
grasping mechanisms include stops that determine y-axis positions
of objects that are grasped. Essentially any combination of these
and other embodiments, or components thereof, described herein are
optionally utilized together.
[0009] In particular, the invention includes various related
grasping mechanisms. For example, in one aspect the invention
provides a grasping mechanism that includes movably coupled arms
(e.g., two arms, etc.) in which the arms are movably coupled to
each other such that the arms can move towards or away from each
other along a first axis (e.g., along an x-axis, etc.). Further,
the arms are attached to a body that comprises a resilient coupling
which allows the arms to move in a direction substantially
perpendicular to the first axis (e.g., along a y-axis, etc.).
Although other configurations are optionally utilized (e.g., a
grasp that is at least partially internal to an object, etc.), the
grasping mechanism is typically structured to grasp the object
between the arms. An interface (e.g., a sliding interface, etc.)
between the arms and the body typically include at least one
spring, which spring resiliently couples the arms to the body. In
preferred embodiments, at least one arm includes a stop. In these
embodiments, each arm typically includes the stop. Further, the
stop is generally structured to determine a y-axis position of the
object. In preferred embodiments, the y-axis position of the object
is determined with an accuracy to within about 0.1 millimeters.
Optionally, the stop includes at least one height adjusting surface
and/or at least one support surface. In addition, at least a
portion of the grasping mechanism generally includes a polished or
coated surface (e.g., coated with TEFLON.RTM. or the like) that
reduces friction between the object and the grasping mechanism
relative to an unpolished or non-coated surface when the object is
grasped by the arms. In some embodiments, the arms and/or other
grasping mechanism components (e.g., stops, etc.) comprise one or
more rollers that reduce friction between the object and the
grasping mechanism, relative to arms that lack the rollers, when
the object is grasped by the arms.
[0010] In preferred embodiments, one or more of the arms include at
least one support surface and/or at least one height adjusting
surface. For example, in one preferred embodiment, each support
surface is disposed between two height adjusting surfaces, which
height adjusting surfaces are angled to push the object into
contact with the support surface when the object is grasped. The
support surface and the height adjusting surface typically form a
channel to grasp the object. In particular, the support surface
generally includes a substantially horizontal surface to support
the object and the height adjusting surface generally includes an
angled surface that intersects with the substantially horizontal
surface, which angled surface pushes the object into contact with
the substantially horizontal surface when the arms grasp the
object. Typically, the support surface determines an x-axis
position of the object and the height adjusting surface determines
a z-axis position of the object when the arms grasp the object. For
example, the x-axis and z-axis positions of the object are
generally determined with an accuracy to within about 0.1
millimeters. In addition, in some embodiments, the one or more arms
include a pivot member, which pivot member includes the support
surface and the height adjusting surface. In preferred embodiments,
the pivot member is resiliently coupled to the arm, e.g., by one or
more springs that couple the pivot member to the arm. In some
embodiments, the arm further includes a stop in which the stop and
the pivot member (e.g., individually or as a single unit) are
resiliently coupled to the arm, e.g., by one or more operably
connected springs or the like.
[0011] The grasping mechanism is generally movably connected to a
boom, which boom is movably connected to a base. The boom typically
rotates about 360 degrees. Also, the boom generally moves
vertically and horizontally and optionally, extends and retracts.
In addition, the boom and the base generally include a robot. The
grasping mechanism typically further includes at least one
controller operably connected to the grasping mechanism, which
controller controls movement of the grasping mechanism. The
controller typically further controls movement of the boom. The
controller typically includes at least one logic device having one
or more logic instructions that direct the grasping mechanism to
contact the object such that the object is pushed against a push
surface by a stop, whereby the resilient coupling allows the arms
to reversibly recede from an initial position, and grasp at least a
section of the object with the arms, after which the arms advance
at least substantially back to the initial position. The arms
typically each include a channel and the logic instructions
optionally further direct the grasping mechanism to partially close
prior to the contacting step to position the section of the object
at least partially within the channel. The logic instructions
typically further direct the grasping mechanism to remove the
object from a first position and place the object at a second
position.
[0012] In preferred embodiments, a deflectable member deflectively
couples the grasping mechanism to the boom. The deflectable member
typically includes a breakaway (e.g., a collision sensor that
detects angular, rotational, and/or compressive forces encountered
by the grasping mechanism). To illustrate, the deflectable member
deflects when the grasping mechanism contacts the object or another
item with a force greater than a preset force. The preset force
generally includes a torque force and/or a moment force that ranges
between about 1.0 Newton-meter and about 10.0 Newton-meters. In
addition, the grasping mechanism typically also includes at least
one sensor that communicates with the controller, e.g., to
determine a location of the gripper apparatus relative to the
object. The sensor is optionally selected from, e.g., an optical
sensor, a photoelectric sensor, an infrared sensor, a position
sensor, a laser distance sensor, a magnetic sensor, or the
like.
[0013] The invention also provides a grasping mechanism that
includes arms that are resiliently coupled to a body by a resilient
coupling and movably coupled to each other, which arms are
structured to grasp an object. In addition, at least one arm
includes a stop.
[0014] In another aspect, the invention provides a gripper
apparatus that includes a robot that includes a boom. The gripper
apparatus also includes a grasping mechanism including movably
coupled arms (e.g., two or more arms) that are structured to grasp
an object (e.g., between the arms, etc.) in which the grasping
mechanism is resiliently coupled to the boom by a resilient
coupling. For example, the boom typically moves vertically and
horizontally, and optionally further extends and retracts. In
addition, the gripper apparatus includes a controller operably
connected to at least the grasping mechanism, which controller
controls movement of the grasping mechanism. Typically, the
controller is operably connected to the robot and further controls
movement of the robot. In some embodiments, the resilient coupling
(e.g., a sliding interface or the like) between the grasping
mechanism and the boom comprises at least one spring, which spring
resiliently couples the grasping mechanism to the boom. Typically,
at least one, and often each, arm further includes a stop. In these
embodiments, the controller generally includes a logic device
having one or more logic instructions that direct the gripper
apparatus to contact the object such that the object is pushed
against a push surface by the stop, whereby the resilient coupling
allows the arms to reversibly recede from an initial position, and
grasp at least a section of the object with the arms, after which
the arms advance at least substantially back to the initial
position. Additionally, the logic instructions typically further
direct the gripper apparatus to remove the object from a first
position and place the object at a second position. In addition, at
least a portion of the grasping mechanism generally includes a
polished or coated surface (e.g., coated with TEFLON.RTM. or the
like) that reduces friction between the object and the grasping
mechanism relative to an unpolished or non-coated surface when the
object is grasped by the arms. Friction is also optionally reduced
by incorporating rollers into grasping mechanism surfaces that
contact objects.
[0015] In some embodiments, one or more of the arms comprise at
least one support surface and at least one height adjusting
surface. In these embodiments, each support surface is optionally
disposed between two height adjusting surfaces, which height
adjusting surfaces are angled to push the object into contact with
the support surface when the object is grasped. Optionally, the
support surface comprises a substantially horizontal surface to
support the object and the height adjusting surface comprises an
angled surface that intersects with the substantially horizontal
surface, which angled surface pushes the object into contact with
the substantially horizontal surface when the arms grasp the
object. In certain embodiments, one or more of the arms comprise a
pivot member, which pivot member comprises the support surface and
the height adjusting surface. In these embodiments, the pivot
member is optionally resiliently coupled to the arms. In addition,
the gripper apparatus optionally further comprises a deflectable
member (e.g., a breakaway or the like) that defectively couples the
grasping mechanism to the boom, which deflectable member deflects
when the grasping mechanism contacts an item with a force greater
than a preset force.
[0016] The invention also provides other grasping mechanism
embodiments. In one aspect, for example, the invention relates to a
grasping mechanism that includes movably coupled arms that are
structured to grasp an object in which at least one arm includes at
least one support surface to support the object and at least one
height adjusting surface that pushes the object into contact with
the support surface when the arms grasp the object. In certain
embodiments, for example, each support surface is disposed between
two height adjusting surfaces, which height adjusting surfaces are
angled to push the object into contact with the support surface
when the object is grasped. In another aspect, the invention
provides a grasping mechanism that includes movably coupled arms
that are structured to grasp an object in which at least one arm
includes a pivot member (e.g., a resiliently coupled pivot member)
that aligns with the object when the arms grasp the object. In
still another aspect, the invention relates to a grasping mechanism
that includes movably coupled arms that are structured to grasp an
object in which at least one arm includes a stop that determines a
y-axis position of the object.
[0017] In another aspect, the invention provides a grasping
mechanism that includes movably coupled arms (e.g., two movably
coupled arms, etc.) that are structured to grasp an object in which
at least one arm comprises a pivot member that aligns with the
object when the arms grasp the object (e.g., between the arms,
etc.). In some embodiments, the pivot member is resiliently coupled
to the arm. Typically, each arm comprises the pivot member.
[0018] The grasping mechanism is typically also movably connected
to a boom, which boom is movably connected to a base. The boom and
the base generally comprise a robot. In addition, the grasping
mechanism typically further includes a controller coupled to the
grasping mechanism, which controller controls movement of the
grasping mechanism. The controller also typically further controls
movement of the boom. Optionally, the grasping mechanism further
comprises at least one sensor that communicates with the controller
to determine a location of the grasping mechanism relative to the
object. The boom generally moves vertically and horizontally, and
optionally extends and retracts. In some embodiments, the grasping
mechanism further includes a deflectable member that deflectively
couples the grasping mechanism to the boom, which deflectable
member (e.g., a breakaway, etc.) deflects when the grasping
mechanism contacts an item with a force greater than a preset
force. In certain embodiments, the grasping mechanism further
includes at least one push surface and one or more of the arms
further comprise a stop that determines a y-axis position of the
object when the grasping mechanism pushes the object against the
push surface. In these embodiments the y-axis position of the
object is generally determined with an accuracy to within about 0.1
millimeters.
[0019] In other aspects, the invention provides a gripper apparatus
that includes a grasping mechanism comprising movably coupled arms
that are structured to grasp an object. At least one arm includes a
stop and a pivot member having: a) a support surface to support the
object, and b) a height adjusting surface that pushes the object
into contact with the support surface such that when the arms grasp
the object the support surface and the height adjusting surface
determine at least a z-axis position of the object. The gripper
apparatus also includes a deflectable member that defectively
couples the grasping mechanism to a boom and a controller coupled
to the grasping mechanism, which controller controls movement of
the grasping mechanism. In addition, the gripper apparatus also
includes at least one push surface against which the gripper
apparatus pushes the object into contact with the stop to determine
a y-axis position of the object.
[0020] In still another aspect, the invention relates to various
methods. For example, the invention provides methods that include
providing a gripper apparatus that includes a controller coupled
grasping mechanism structured to grasp an object with arms (e.g.,
two arms, etc.) that extend from a body of the grasping mechanism
in which at least one arm includes a stop. Further, at least
two-grasping mechanism components are resiliently coupled together
(e.g., along a y-axis direction, etc.). To illustrate, in certain
embodiments, the arms are resiliently coupled to the body of the
grasping mechanism. Optionally, pivot members and/or stops are
resiliently coupled to the arms. The methods also include pushing
the object against a push surface and into contact with the stop,
whereby the resilient coupling allows the arms to reversibly recede
from an initial position (e.g., an initial y-axis position, etc.),
and grasping at least a section of the object with the arms, after
which the arms advance at least substantially back to the initial
position, thereby grasping the object. Although other
configurations are optionally utilized, the grasping mechanism is
generally structured to grasp the object (e.g., a plate, a sample
plate, a micro-well plate, a reaction block, a reaction block
carrier, a sample holder, a petri dish, a test tube, a vial, a
crucible, a reaction vessel, a reaction flask, a semi conductor
wafer, a CD, a tray, or the like) between the arms. The object is
typically positioned at a first position and the method generally
further includes removing the object from the first position with
the gripper apparatus and placing the object at a second position
with the gripper apparatus.
[0021] In preferred embodiments, one or more arms include at least
one support surface and at least one height adjusting surface. The
support surface and the height adjusting surface typically form a
channel to grasp the object. In particular, the support surface
generally includes a substantially horizontal surface that supports
the object and the height adjusting surface generally includes an
angled surface that pushes the object into contact with the
substantially horizontal surface during the grasping step. To
illustrate, the methods typically determine three translational
axis positions of the object with an accuracy to within about 0.1
millimeters. In addition, the one or more arms typically include a
pivot member (e.g., a resiliently coupled pivot member), which
pivot member includes the support surface and the height adjusting
surface. The grasping mechanism is generally movably connected to a
boom, which boom is movably connected to a base. The boom and the
base typically include a robot. Further, the boom generally moves
vertically and horizontally, and optionally, extends and retracts.
In addition, the boom generally rotates about 360 degrees. The
gripper apparatus also optionally includes a deflectable member
(e.g., a breakaway, etc.) that deflectively couples the grasping
mechanism to the boom and the methods further include deflecting
the deflectable member when the grasping mechanism contacts the
object or another item with a force greater than a preset
force.
[0022] The invention also provides a method of determining an
x-axis position and a z-axis position of an object. The method
includes providing a gripper apparatus that includes a controller
coupled grasping mechanism including movably coupled arms that are
structured to grasp an object in which at least one arm includes a
support surface and a height adjusting surface. The method also
includes grasping at least a section of the object with the arms
such that the height adjusting surface pushes the object into
contact with the support surface, thereby determining the x-axis
position and the z-axis position of the object. In some
embodiments, one or more of the arms include a stop and the method
further includes providing at least one push surface, and pushing
the object against the at least one push surface and into contact
with the stop using the gripper apparatus, thereby determining a
y-axis position of the object. Typically, the object is positioned
at an initial position and the method generally further includes
removing the object from the initial position with the gripper
apparatus and placing the object at a new position with the gripper
apparatus.
[0023] In addition, the invention relates to a method of grasping
an object that includes providing a gripper apparatus that includes
a controller coupled grasping mechanism including movably coupled
arms that are structured to grasp the object in which at least one
arm includes a pivot member. The method also includes grasping at
least a section of the object such that the pivot member aligns
with the object, thereby grasping the object. In some embodiments,
one or more of the arms include a stop and the method further
includes providing at least one push surface, and pushing the
object against the at least one push surface and into contact with
the stop using the gripper apparatus, thereby determining a y-axis
position of the object. Typically, the object is positioned at an
initial position and the method further includes removing the
object from the initial position with the gripper apparatus and
placing the object at a new position with the gripper
apparatus.
[0024] The invention additionally relates to a method of
determining a y-axis position of an object. The method includes
providing a gripper apparatus that includes a controller coupled
grasping mechanism having movably coupled arms that are structured
to grasp the object in which at least one arm comprises a stop, and
providing at least one push surface. The method also includes
grasping at least a section of the object with the arms, and
pushing the object against the at least on& push surface and
into contact with the stop using the gripper apparatus, thereby
determining the y-axis position of an object. Typically, the object
is-positioned at an initial position and the method further
includes removing the object from the initial position with the
gripper apparatus and placing the object at a new position with the
gripper apparatus.
[0025] The invention also relates to a method of grasping an object
that includes providing a gripper apparatus that includes a
controller coupled grasping mechanism having movably coupled arms
that are structured to grasp the object and a deflectable member
that deflectively couples the grasping mechanism to a boom. The
method also includes grasping at least a section of the object with
the arms such that the deflectable member deflects when the
grasping mechanism contacts the object or another item with a force
greater than a preset force.
[0026] The invention further provides a method of determining three
translational axis positions of an object. The method includes
providing a gripper apparatus that includes a controller coupled
grasping mechanism including movably coupled arms that are
structured to grasp an object. At least one arm includes a pivot
member having a support surface and a height adjusting surface in
which one or more of the arms include a stop. Further, a
deflectable member defectively couples the grasping mechanism to a
boom. The method also includes providing at least one push surface.
In addition, the method includes grasping at least a section of the
object with the arms such that the height adjusting surface pushes
the object into contact with the support surface to determine the
x-axis position and the z-axis position of the object. Furthermore,
the method includes pushing the object against the at least one
push surface and into contact with the stop, using the gripper
apparatus, to determine a y-axis position of the object, thereby
determining the three translational axis positions of the
object.
[0027] The invention also provides a method of grasping an object
that includes providing a gripper apparatus that comprises a
controller coupled grasping mechanism having movably coupled arms
that are structured to grasp an object. At least one arm comprises
a stop, and at least two grasping mechanism components are
resiliently coupled to each other by a resilient coupling. The
method also includes contacting the object such that the object is
pushed against a push surface by the stop, whereby the resilient
coupling allows the arms to reversibly recede from an initial
position. In addition, the method includes grasping at least a
section of the object with the arms, after which the arms advance
at least substantially back to the initial position. The method
also generally further includes removing the object from a
first-position and placing the object at a second position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The nature, goals, and advantages of the invention will
become more-apparent to those skilled in the art after considering
the following detailed description when read in connection with the
accompanying drawings in which like reference numerals identify
like components throughout the drawings, unless the context
indicates otherwise. It will be understood that some or all of the
figures may be schematic representations for purposes of
illustration and do not necessarily depict the actual relative
sizes or locations of the elements shown.
[0029] FIG. 1 schematically depicts one embodiment of a gripper
apparatus from a side elevational view.
[0030] FIG. 2 schematically illustrates one embodiment of a
grasping mechanism coupled to a boom of a robot from a perspective
view.
[0031] FIG. 3 schematically shows a front elevational view of the
grasping mechanism of FIG. 2.
[0032] FIG. 4 schematically depicts a plan view of the grasping
mechanism of FIG. 2.
[0033] FIGS. 5A-D schematically depict various exemplary
embodiments of stops.
[0034] FIGS. 6A and B schematically show relative orientations of
pivot members, and a sample plate as a gripper apparatus grasps the
sample plate according to one embodiment of the invention.
[0035] FIGS. 7A-D schematically depict cross-sectional profiles of
various exemplary embodiments of pivot members.
[0036] FIG. 8 schematically illustrates one embodiment of a
grasping mechanism that includes arms that are resiliently coupled
to a body.
[0037] FIG. 9 schematically illustrates the grasping mechanism of
FIG. 8 coupled to a boom of a robot from a perspective view.
[0038] FIG. 10 schematically shows a front elevational-view of the
grasping mechanism of FIG. 8.
[0039] FIG. 11 schematically depicts grasping arms and a sample
plate from a perspective view.
[0040] FIG. 12 is a block diagram illustrating one method of
grasping an object with a gripper apparatus.
[0041] FIGS. 13A and B schematically illustrate the approach of a
grasping mechanism, which is resiliently coupled to a robotic boom,
to a sample plate according to one embodiment of a grasping method
of the invention. FIG. 13A schematically illustrates the approach
from a top view, whereas FIG. 13B schematically illustrates the
approach from a perspective view.
[0042] FIGS. 14A and B schematically illustrate the stops of the
grasping mechanism of FIG. 13 in contact with a sample plate
according to one embodiment of a grasping method of the invention.
FIG. 14A schematically illustrates the contact from a top view,
whereas FIG. 14B schematically illustrates the contact from a
perspective view.
[0043] FIGS. 15A and B schematically illustrate the arms of the
grasping mechanism of FIG. 13 grasping a sample plate according to
one embodiment of a grasping method of the invention. FIG. 15A
schematically illustrates the grasp from a top view, whereas FIG.
15B schematically illustrates the grasp from a perspective
view.
[0044] FIG. 16 schematically shows relative orientations of pivot
members, stops, and a sample plate as a gripper apparatus grasps
the sample plate according to one embodiment of the invention.
[0045] FIGS. 17A and B schematically illustrate the grasping
mechanism of FIG. 13 removing a sample plate from a station shelf
according to one embodiment of a grasping method of the invention.
FIG. 17A schematically illustrates the removal from a top view,
whereas FIG. 17B schematically illustrates the removal from a
perspective view.
[0046] FIG. 18 is a block diagram illustrating one method of
grasping an object with a gripper apparatus.
[0047] FIG. 19 schematically shows one embodiment of a push surface
that can be used to locate or determine the y-axis position of an
object.
[0048] FIG. 20 schematically depicts another embodiment of a push
surface that can be used to locate or determine the y-axis position
of an object.
DETAILED DISCUSSION OF THE INVENTION
I. DEFINITIONS
[0049] Before describing the present invention in detail, it is to
be understood that this invention is not limited to particular
devices or systems, which can, of course, vary. It is also to be
understood that the terminology used herein is for the purpose of
describing particular embodiments only, and is not intended to be
limiting. Further, unless defined otherwise, all technical and
scientific terms used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which the
invention pertains. In describing and claiming the present
invention, the following terminology will be used in accordance
with the definitions set out below.
[0050] The term "vertical" refers to a plane that is approximately
perpendicular a plane of a horizontal or supporting surface.
[0051] The term "horizontal" refers to a plane that is
approximately parallel to a plane of a supporting surface and
approximately perpendicular a vertical plane.
[0052] The "x-axis" refers to an axis in a three-dimensional
rectangular coordinate system that is substantially parallel to a
horizontal plane and approximately perpendicular to both the y- and
z-axes.
[0053] The "y-axis" refers to an axis in a three-dimensional
rectangular coordinate system that is substantially parallel to a
horizontal plane and approximately perpendicular to both the x- and
z-axes.
[0054] The "z-axis" refers to an axis in a three-dimensional
rectangular coordinate system that is substantially parallel to a
vertical plane and approximately perpendicular to both the x- and
y-axes.
II. GRIPPING DEVICES
[0055] The present invention provides gripper apparatus and
grasping mechanisms that grasp and manipulate objects with greater
accuracy and throughput than preexisting technologies. For example,
unlike the devices of the invention, conventional robotic systems
generally achieve an object positioning accuracy or geometric
tolerance of at most about 1 mm. Although such a tolerance is
adequate, e.g., for processing some lower density sample plates,
such a tolerance is inadequate for higher density plates, such as a
plate with 1536 or more wells. Indeed, a positioning error of 1 mm
for a 1536-well sample plate could cause a sample or reagent to be
deposited entirely in a non-specified well and/or cause damage to
the apparatus. The apparatus of the invention also grasp objects
stronger and more securely than preexisting devices and as a
consequence, grasping processes can be performed more rapidly,
which leads to improved throughput.
[0056] In addition, preexisting robotic grippers typically rely on
friction to control the object in all six degrees of freedom, which
include three translational and three rotational degrees of
freedom. In contrast, in certain embodiments of the invention,
gripper apparatus positively locate or position work pieces or
other objects in five degrees of freedom (two translational and
three rotational). The remaining translational degree of freedom,
which typically corresponds to the y-axis, is generally positively
determined or stopped in one direction by a stop or backstop
component and controlled by friction in the opposite direction.
This approach is also generally preferred to positively locating an
object in all six degrees of freedom, which would involve
surrounding a given object, e.g., with a grasping mechanism or
assembly. A better engineering compromise provided by certain
aspects of the present invention is to grasp only one end of a
given work piece, which provides for smaller and stiffer grasping
mechanisms than is provided by preexisting technologies. Smaller
grasping mechanisms are also able to access objects in more
constrained locations than many preexisting devices are capable. To
overcome the friction control in the one y-axis direction, certain
embodiments include pushing an object against solid wall or other
push surface after it has been picked up. This slides the object in
the one frictionally controlled direction until it contacts a
backstop on the gripper mechanism. At that point, the position of
the object is accurately located or determined in all six degrees
of freedom. In other embodiments, the object is contacted with the
gripper mechanism stops, e.g., prior to grasping or otherwise
contacting the object with other gripper mechanism components, such
as-gripper mechanism arms. These embodiments also accurately
determine the position of the object in all six degrees of
freedom.
[0057] FIG. 1 schematically depicts one embodiment of gripper
apparatus 10 from a side elevational view. Robotic gripper
apparatus 10 is an automated robotic device, e.g., for accurately
and securely grasping, moving, manipulating and/or positioning
objects. The design of robotic gripper apparatus 10 is optionally
varied to accommodate different types of objects. One preferred
embodiment of robotic gripper apparatus 10 is manufactured to grasp
sample plates (e.g., microwell plates or the like). Other exemplary
objects include, e.g., reaction, blocks, reaction block carriers,
petri dishes, test tubes, vials, crucibles, reaction vessels or
flasks, hazardous material containers, medical devices or
components, electronic devices or components, semi conductor
wafers, CDs, trays, etc. Reaction blocks and reaction block
carriers are described in greater detail in, e.g., U.S. Ser. No.
09/947,236, entitled "PARALLEL REACTION DEVICES," filed Sep. 5,
2001 by Micklash et al., and U.S. Ser. No. 60/351,821, entitled
"DEVICES, SYSTEMS, AND METHODS OF MANIFOLDING MATERIALS," filed
Jan. 25, 2002 by Micklash et al., the disclosures of which are
incorporated by reference in their entirety for all purposes.
[0058] In a preferred embodiment illustrated in FIG. 1, robotic
gripper apparatus 10 includes grasping mechanism 20 movably
connected to boom 12, which is movable relative to base 14.
Controller 15, which optionally includes a general purpose
computing device, controls the movements of, e.g., grasping
mechanism 20 and boom 12 in a work perimeter that includes one or
more stations 30 that can receive and support sample plates 25.
Controllers are described further below. As shown, grasping
mechanism 20 is designed to grasp sample plates 25 and move them,
e.g., from one station 30 to another station 30 or to other
locations within the work perimeter of robotic gripper apparatus
10. Although FIG. 1 illustrates only a single work perimeter, more
work perimeters, e.g., each including a gripper apparatus, are
optionally utilized, depending upon the specific application.
Additional details relating to robotic gripping devices are
provided in, e.g., U.S. Pat. No. 5,871,248, entitled "ROBOT
GRIPPER," which issued Feb. 16, 1999 to Okogbaa et al. and U.S.
Pat. No. 5,945,798, entitled "SYSTEM FOR DETERMINING PART PRESENCE
AND GRIP PRESSURE FOR A ROBOTIC GRIPPING DEVICE," which issued Aug.
31, 1999 to Stagnitto et al.
[0059] The controllers of the present invention typically include
at least one computer (or other information appliance) operably
connected to or included within various apparatus or system
components (e.g., grasping mechanisms, booms, etc.). The computer
typically includes system software or logic instructions that
direct, e.g., the movement of robotic booms, the movement of
grasping mechanism arms, and/or the movement of other gripper
apparatus components. Additionally, a gripper apparatus is
optionally coupled to an appropriately programmed processor or
computer which functions to instruct the operation of device
instrumentation or components in accordance with preprogrammed or
user input instructions, receive data and information from these
instruments, and interpret, manipulate and report this information
to the user. As such, the computer is typically appropriately
coupled to one or more of these instruments (e.g., including an
analog to digital or digital to analog converter as needed).
[0060] In certain embodiments, Microsoft WINDOWS.TM. software
written using instrument control language (ICL) scripts is adapted
for use in the gripper apparatus and systems of the invention.
Optionally, standard desktop applications such as word processing
software (e.g., Microsoft Word.TM. or Corel WordPerfect.TM.) and
database software (e.g., spreadsheet software such as Microsoft
Excel.TM., Corel Quattro Pro.TM., or database programs such as
Microsoft Access.TM. or Paradox.TM.) can be adapted to the present
invention by inputting user-defined instructions, such as defining
work piece locations, preset forces for breakaways, or the like.
For example, the systems optionally include the foregoing software
having the appropriate, e.g., work piece positional information
used in conjunction with a user interface (e.g., a GUI in a
standard operating system such as a Windows, Macintosh or LINUX
system) to manipulate such information.
[0061] The computer can be, e.g., a PC (Intel x86 or Pentium
chip-compatible DOS.TM., OS2.TM., WINDOWS.TM., WINDOWS NT.TM.,
WINDOWS95.TM., WINDOWS98.TM., WINDOWS2000.TM., WINDOWSXP.TM.,
LINUX-based machine, a MACINTOSH.TM., Power PC, or a UNIX-based
(e.g., SUN.TM. work station) machine or other common commercially
available computer which is known to one of skill. Software for
performing, e.g., object grasping, object translocation, or the
like is optionally easily constructed by one of skill using a
standard programming language such as Visual basic, Fortran, Basic,
Java, or the like. Any controller or computer optionally includes a
monitor which is often a cathode ray tube ("CRT") display, a flat
panel display (e.g., active matrix liquid crystal display, liquid
crystal display, etc.), or others. Computer circuitry is often
placed in a box (e.g., within the base of the gripper apparatus of
the invention), which includes numerous integrated circuit chips,
such as a microprocessor, memory, interface circuits, and others.
The box also optionally includes a hard disk drive, a floppy disk
drive, a high capacity removable drive such as a writeable CD-ROM,
and other common peripheral elements. Inputting devices such as a
keyboard (e.g., a touch screen, etc.) or mouse optionally provide
for input from a user.
[0062] The computer typically includes appropriate software for
receiving user instructions, either in the form of user input into
a set of parameter fields, e.g., in a GUI, or in the form of
preprogrammed instructions, e.g., preprogrammed for a variety of
different specific operations. The software then converts these
instructions to appropriate language for instructing the grasping
mechanism, the boom, or the like to carry out the desired
operation, e.g., varying or selecting the rate or mode of movement
of various system components, or the like. The computer then
receives the data from the one or more sensors/detectors included
within the apparatus or system, and interprets the data, either
provides it in a user understood format, or uses that data to
initiate further controller instructions, in accordance with the
programming, e.g., such as in monitoring boom location, grasping
mechanism location, or the like.
[0063] Referring again to FIG. 1, boom 12 is generally capable of
about 360 degrees of rotation. In addition, boom 12 typically moves
vertically and horizontally, e.g., to align grasping mechanism 20
with higher or lower stations 30. Although many types of robots can
be used in robotic gripper apparatus 10, in a preferred embodiment
of the invention, a Stubli RX-60 robot (provided by Stubli
Corporation of South Carolina, U.S.A.), which includes boom 12 and
base 14, is utilized.
[0064] Boom 12 is configured to extend and retract from base 14.
This defines the work perimeter for robotic gripper apparatus 10.
Stations 30 are positioned within the work perimeter of boom 12 as
are hand-off areas or other areas that are configured to support or
receive objects grasped and moved by grasping mechanism 20. For
example, sample plate 25 is positioned on station shelf 33 and can
be grasped by grasping mechanism 20 and moved to another position
by boom 12. As mentioned above, in preferred embodiments, sample
plate 25 includes multiple wells, with each well configured to hold
a sample. For example, sample plate 25 optionally includes, e.g.,
6, 12, 24, 48, 96, 192, 384, 768, 1536, or another number of
wells.
[0065] Referring now to FIGS. 2 and 3, one embodiment of grasping
mechanism 20 is illustrated. Grasping arm A and grasping arm B
extend from gripper mechanism body 22. Although the embodiments
described herein include two arms for purposes of clarity of
illustration, the grasping mechanisms of the invention optionally
include more than two arms, e.g., about three, about four, about
five, about six, or more arms. Further, although in preferred
embodiments grasping mechanism arms are structured to grasp objects
between the arms, other configurations are also optionally
included, e.g., such that certain objects can be at least
partially, if not entirely, grasped internally, e.g., via one or
more cavities disposed in one or more surfaces of the particular
objects.
[0066] As further shown in FIGS. 2 and 3, grasping mechanism body
22 is connected to a deflectable member, such as breakaway 60,
which is deflectably coupled to boom 12. Breakaway 60 is typically
structured to detect angular, rotational, and compressive forces
encountered by grasping mechanism 20. The breakaway acts as a
collision protection device that greatly reduces the possibility of
damage to components within the work perimeter by, e.g., the
accidental impact of grasping mechanism 20 or grasping arms A and B
with objects or other items (e.g., station shelves, etc.) within
the work perimeter. For example, when grasping mechanism 20 impacts
an object, breakaway 60 will deflect, thereby also causing grasping
mechanism 20 to deflect. To further illustrate, deflectable members
in the apparatus of the invention generally deflect when the
grasping mechanism contacts an object or other item with a force
greater than a preset force. The preset force typically includes a
torque force and/or a moment force that, e.g., ranges between about
1.0 Newton-meter and about 10.0 Newton-meters. When controller 15
detects the deflection, it generally stops movement of the robotic
gripper mechanism. In a preferred embodiment, breakaway 60 is a
"QuickSTOP.TM." collision sensor manufactured by Applied Robotics
of Glenville, N.Y., U.S.A. Breakaway 60 is typically a dynamically
variable collision sensor that operates, e.g., on an air pressure
system. Other types of impact detecting devices are optionally
employed, which operate hydraulically, magnetically, or by other
means known in the art. In certain embodiments, breakaways are not
included in the gripper apparatus of the invention. In these
embodiments, grasping mechanisms are typically directly-coupled to
robotic booms.
[0067] As also shown, body 22 connects grasping arms A and B to
breakaway 60. When directed by controller 15, body 22 moves
grasping arms A and B away from or toward each other, e.g., to
grasp and release objects. In a preferred embodiment, body 22 is
manufactured by Robohand of Monroe, Conn., U.S.A. Typically, the
grasping arms are pneumatically driven, but other means for
operating the arms are also optionally utilized, such as magnetic-
and hydraulic-based systems.
[0068] Referring to FIG. 4, grasping arms A and B extend from body
22 and include gripper pads or pivot members 35, which pivotally
align with objects upon contact, e.g., when grasping arms A and B
are closed upon an object. As described further below, pivot
members typically include support surfaces and height adjusting
surfaces (e.g., that form channels to grasp objects), which
determine x-axis and z-axis positions of objects when the arms
grasp the objects. The support surface typically includes a
substantially horizontal surface to support the object. The height
adjusting surface typically includes an angled surface that
intersects with the substantially horizontal surface, which angled
surface pushes the object into contact with the substantially
horizontal surface when the arms grasp the object. In this way, the
x-axis and z-axis positions of a given object are determined with
an accuracy to within about 0.1 millimeters. As described further
below, grasping mechanism arms optionally do not include pivot
members.
[0069] Positioned proximate to pivot members 35 are sensors 55 and
stops 50. Sensors 55 communicate with controller 15 and determine
the location of 30 objects adjacent or relative to arms A and B. In
a preferred embodiment, sensors 55 are optical sensors, but
photoelectric, infrared, magnetic, position, laser distance, or
other suitable sensors can be employed. Stops 50 are optionally
included to determine y-axis positions of objects, e.g., with an
accuracy to within about 0.1 millimeters. FIGS. 5A-D schematically
depict profiles of certain exemplary embodiments of stops that are
optionally utilized with the apparatus described herein. FIG. 5C
schematically shows the stop depicted in FIG. 5B from a perspective
view to further illustrate that in this embodiment, the stop
includes two height adjusting surfaces (i.e., angled surfaces)
which push, e.g., sample plate edges toward the center of the stop
when the plate is grasped. In certain embodiments, sensors 55
and/or stops 50 are not included in the gripper apparatus.
[0070] Referring further to FIG. 4 and now also to FIGS. 6A and B
with gripper pads or pivot members 35 pivotally mounted to arms A
and B schematically illustrated. As shown, channel 37 extends along
a long axis of each pivot member 35. Channel 37 includes
substantially horizontal surface 40 and angled surface 45. To
further illustrate, FIGS. 7A-D schematically depict cross-sectional
profiles of various exemplary pivot member embodiments that are
optionally used in the devices described herein with channel 37
indicated. In a preferred embodiment, pivot members 35 are separate
device components that are pivotally mounted to arms A and B. One
alternative embodiment of robotic gripper apparatus 10 includes
channel 37 fabricated into arms A and B. i.e., not into separate
pivot members. In these embodiments, arms A and B optionally pivot,
with respect to body 22. Grasping arms A and B, pivot members 35,
and other grasping mechanism components are typically constructed
from metals (e.g., aluminum, etc.), alloys, or the like, but
dielectric materials, such as plastic or other types of materials,
are also optionally utilized.
[0071] In other preferred embodiments, grasping arms are
resiliently coupled to robotic booms such that when an object
contacts stops on the grasping arms, the arms reversibly recede
from an initial position, e.g., to determine a y-axis position of
an object prior to determining the x-axis and z-axis positions of
the object. Certain of these embodiments are schematically
illustrated in FIGS. 8-10. In particular, FIG. 8 schematically
depicts one embodiment of grasping mechanism 20 that includes arms
A and B resiliently coupled to body 22 via resilient coupling or
slideable interface 52. Slideable interfaces typically include
springs, which resiliently couple, e.g., grasping arms to grasping
mechanism bodies so that at least the grasping arms are pushed in a
y-direction (e.g., a positive y-direction) opposite the movement in
the y-direction (e.g., a negative y-direction) of the boom upon
contacting a sample plate or other object with a force of, e.g.,
several pounds. Other amounts of force are also optionally
utilized. The resiliency provided by the slideable interfaces of
the present invention typically includes between about 0.5 mm and
about 25 mm, more typically between about 1 mm and about 10 mm, and
still more typically between about 1.5 mm and about 5 mm (e.g.,
about 2 mm, about 3 mm, or about 4 mm), of low friction compliance
in the y-direction. Greater resiliency is also optionally provided
by the slideable interfaces. Such resiliency is optionally provided
by other interfaces that include, e.g., pneumatic mechanisms,
hydraulic mechanisms, or the like. In certain embodiments, the
slideable interfaces of the invention also utilize precision
bearing slides with minimal friction and minimal backlash in both
the x- and z-directions. As further shown, arms A and B include
stops 50 and pivot members 35. As mentioned, the embodiment of
grasping mechanism 20 schematically illustrated in FIG. 8 is
optionally used to determine the y-axis position of an object prior
to grasping the object between the arms, that is, prior to
determining the x-axis and z-axis positions of the object. Methods
that include grasping mechanisms such as the one schematically
shown in FIG. 8 are described further below.
[0072] FIG. 9 schematically illustrates grasping mechanism 20 of
FIG. 8 coupled to boom 12 of a robot from a perspective view. To
further illustrate, FIG. 10 schematically shows a front elevational
view of grasping mechanism 20 of FIG. 8. As shown in this
embodiment, grasping mechanism 20 is connected to boom 12 via
breakaway 60. Breakaways are described in greater detail above.
Optionally, breakaways are not included in the gripper apparatus or
systems of the invention, in which case grasping mechanisms, such
as grasping mechanism 20 of FIGS. 8-10, are directly connected,
e.g., to boom 12.
[0073] In preferred embodiments, at least a portion of the grasping
mechanism includes a polished or coated surface (e.g., coated with
TEFLON.RTM. or the like) that reduces friction between the object
and the grasping mechanism relative to an unpolished or non-coated
surface when the object is grasped by the arms. Friction is also
optionally reduced by incorporating one or more rollers into
grasping mechanism surfaces that contact objects (e.g., stops,
pivot members, etc.) or by another anti-friction mechanism. In
embodiments of the invention that include stops and resilient
couplings or slideable interfaces, the use of such anti-friction
mechanisms is important, for example, since sample plates are
pushed against the stops with the force of at least the slider
springs during object pick-up and drop-off processes. These
processes are described in greater detail below.
III. GRASPING METHODS
[0074] Referring again to FIGS. 1 and 6, and now also to FIGS. 11
and 12, the operation of robotic gripper apparatus 10 will now be
described. In a preferred embodiment, robotic gripper apparatus 10
grips, transports and positions sample plate 25, e.g., from station
30 to another station 30, to a hand-off area, or to another
location within the work perimeter of robotic gripper apparatus 10.
As shown in FIG. 11, sample plate 25 includes a plurality of
closely arranged sample wells. Each well in sample plate 25 is
square with each side of the well having a length of about 2
millimeters. During a high throughput process, discrete fluid
samples may be deposited in each well, which necessitates a
positioning accuracy to within about 0.1 millimeters. The gripper
apparatus of the invention are capable of achieving this
positioning accuracy.
[0075] When employed in a high throughput process, controller 15
instructs robotic gripper apparatus 10 to move boom 12 toward a
station 30. In a preferred embodiment, sample plates 25 are
vertically arranged on station shelves 33. When instructed by
controller 15, boom 12 extends grasping mechanism 20 toward a
selected station 30 and between station shelves 33. Sample plates
25 are located on station shelves 33. Sensor 55 detects a station
shelf 33 as grasping mechanism 20 moves closer to the selected
shelf. As shown in FIG. 11, when station shelf 33 is detected,
grasping arms A and B move up and contact sample-plate edge 27 with
pivot members 35. In-the embodiment shown, sample plate 25 is
substantially rectangular with at least two substantially straight
sample plate edges 27. Other objects may also be grasped by
grasping mechanism 20. Typically, the objects will have straight
sections that can engage pivot members 35. Optionally, pivot
members 35 are curved to include a curved channel 37 suitable for
grasping curved objects, or otherwise shaped to accommodate the
particular object to be grasped.
[0076] Referring to FIGS. 6A and B, pivot members 35 include
substantially horizontal surface 40 and angle surface 45 that
together form channel 37. As pivot members 35 approach sample plate
25, the vertical or z-axis position of sample plate 25 may not
correspond with pivot members 35. In this case, when pivot member
35 engages sample plate edge 27, edge 27 may contact angled surface
45. As the grasping arms A and B move toward one another, pivot
members 35 pivot slightly to align with and push sample plate 25
against horizontal surface 40. By including angled surface 45 on
pivot members 35, the vertical position, as defined by the z-axis,
is determined because angled surface 45 forces sample plate 25 to
contact horizontal surface 40. This is in contrast to conventional
gripping devices that do not define the vertical position of the
grasped object. In addition, with conventional grasping devices, an
object that is misaligned relative to the x-axes, that is, angled
relative to the conventional grasping device, will be grasped at an
angle, thereby only establishing a single point of contact on each
side of the object.
[0077] As illustrated in FIGS. 6A and 11, the present invention
includes pivot members, 35 that pivot to align themselves with
sample plate edge 27, thereby establishing a line of contact 29
with sample plate edge 27. By including pivot members 35 on
grasping arms A and B, the present invention also establishes
accurate side-to-side position, or x-axis position of sample plate
25. Grasping angled plates with the subsequent mispositioning of
the angled plate is thereby eliminated.
[0078] Another step in this embodiment of positioning sample plate
25 includes removing sample plate 25 from station shelf 33. Because
of the unique geometry of channels 37 located in pivot members 35,
the position of sample plate 25 on the x-axis and the z-axis is
determined. The y-axis or fore-and-aft position of sample plate 25,
however, is not known. To determine the y-axis of sample plate 25
in this embodiment, body 22 and boom 12 of the robotic gripper
apparatus 10 are moved to position sample plate 25 proximate to
push surface 65.
[0079] As shown in FIGS. 1 and 3, push surface 65 is positioned in
this embodiment on base 14 of robotic gripper apparatus 10. Push
surface 65 can be located in other locations such as on station 30
or at other locations within the work perimeter of robotic gripper
apparatus 10. Boom 12 pushes sample plate 25 against push surface
65, which pushes sample plate 25 against stops 50 located on
grasping arms A and B. Push surfaces optionally include pins,
walls, raised edges, or any other functionally equivalent
components. Certain exemplary push surfaces 65 are schematically
illustrated in, e.g., FIGS. 19 and 20. By pushing sample plate 25
against stops 50, the y-axis or fore-and-aft position of sample
plate 25 is determined.
[0080] The above-described process of grasping sample plate 25 with
pivot members 35 so that sample plate 25 is forced against
horizontal surface 40 and then removing sample plate 25 from
stations 30 and pushing sample plate 25 against push surface 65
ensures that all three translational axes of sample plate 25 are
determined with an accuracy to within about 0.1 millimeters. In
addition, channel 37 reduces the amount of gripping force that is
typically used to grasp sample plate 25, because sample plate 25
rests on substantially horizontal surface 40. Moreover, because
angled surface 45 traps sample plate 25 against horizontal surface
40 to prevent the tilting of sample plate 25, only a portion (e.g.,
an end section, etc.) of sample plate 25 is grasped. This allows
the easy insertion of the sample plate 25 into constrained
locations, because grasping arms A and B only contact a small
section of sample plate 25. FIG. 12 is a block diagram that further
illustrates grasping an object with a gripper apparatus.
[0081] In another preferred embodiment, the present invention
provides a method of dynamically and accurately locating and
grasping an object that includes determining the y-axis position of
the object prior to determining the z-axis and x-axis positions of
the object. In certain cases, for example, variations in friction
between grasping arms and the object being grasped can cause
variations in the amount of force used to positively push the
object back against stops on grasping arms. If the friction force
is too low, the object may move out of position, e.g., due to
inertial forces after the object is pushed back. If friction is too
high, the object may not push back all the way to the stops and/or,
if a breakaway is included in the apparatus, it may breakaway if
the force exceeds a pre-selected force causing unnecessary
stoppage. Accordingly, one option is to push the object back to the
stops while the grasping arms are open and the frictional force is
zero at the arm-object interfaces. One way to accomplish this is to
provide a resilient or otherwise compliant push surface at every
nest or other location from which the robotic gripper apparatus
grasps an object. This entails a lot of complicated hardware. The
present invention alleviates this problem by including an aspect of
resiliency in certain grasping mechanism embodiments. In some of
these embodiments, for example, a spring loaded, slideable
interface or other resilient coupling is built into the grasping
mechanism. By including, e.g., linear compliance in grasping
mechanisms, it permits object nest locations to have hard push
surfaces instead of compliant push surfaces. In these embodiments,
a gripper apparatus pushes the sample plate or other object to be
picked-up or dropped-off against a push surface to compress the
springs of the resilient coupling. In addition, these push surfaces
are typically designed into each object pick-up and drop-off
location and vary, e.g., depending the configuration of the
particular location. FIGS. 19 and 20 schematically illustrate
examples of these types of push surfaces.
[0082] Referring again to FIGS. 8-10 and also now to FIGS. 13-18, a
method of grasping an object with a resilient grasping mechanism is
described. In particular, FIGS. 13 A and B schematically illustrate
the approach of grasping mechanism 20 to sample plate 25 positioned
on station shelf 33 of station 30. FIG. 13A schematically
illustrates the approach from a top view, while FIG. 13B
schematically illustrates the approach from a perspective view. As
shown, open arms A and B are resiliently coupled to body 22 via
slideable interfaces 52. Before stops 50 of grasping mechanism 20
contact sample plate 25 there is no clearance or separation between
spring stops 54 and the bodies of slideable interfaces 52. That is,
the springs of slideable interfaces 52 are not compressed beyond
their installed compression and slideable interfaces 52 are in
their initial positions or "home states."
[0083] FIGS. 14A and B schematically illustrate stops 50 of
grasping mechanism 20 in contact with sample plate 25. FIG. 14A
schematically illustrates this contact from a top view, whereas
FIG. 14B schematically illustrates the contact from a perspective
view. As shown, when stops 50 contact sample plate 25, arms A and B
resiliently slide in the opposite direction from the movement of
boom 12 from the initial positions shown in FIGS. 13A and B. As
also shown, arms A and B are open, that is, pivot members 35 have
not contacted sample plate 25. The contact between stops 50 and
sample plate 25 determine the y-axis position of the sample plate
25. In this process, several millimeters of clearance are typically
produced between spring stops 54 and the bodies of slideable
interfaces 52. One advantage of this grasping method is that the
robot typically does not need to be programmed perfectly for each
sample plate location and each type of sample plate.
[0084] FIGS. 15A and B schematically illustrate pivot members 35
contacting sample plate 25 as arms A and B grasp sample plate 25.
In particular, FIG. 15A schematically illustrates the grasp from a
top view, whereas FIG. 15B schematically illustrates the grasp from
a perspective view. As shown, arms A and B remain away from their
initial positions in opposition to the movement of boom 12 via
slideable interfaces 52. That is, the clearance between spring
stops 54 and the bodies of slideable interfaces 52 remains during
this portion of the method. Further, as described above, the x-axis
and z-axis positions of sample plate 25 are determined when pivot
members contact sample plate 25. FIG. 16 further schematically
shows the relative orientations of pivot members 35, stops 50, and
sample plate 25 as grasping mechanism 20 grasps sample plate
25.
[0085] FIGS. 17A and B schematically illustrate grasping mechanism
20 removing sample plate 25 from station shelf 33. FIG. 17A
schematically illustrates the removal from a top view, whereas FIG.
17B schematically illustrates the removal from a perspective view.
As shown, as boom 12 withdraws from station 30, arms A and B slide
back to their initial positions such that spring stops 54 and the
bodies of slideable interfaces 52 are no longer separated from one
another. FIG. 18 is a block diagram that further illustrates an
embodiment of this method of grasping an object such that the
y-axis position of the object is determined before the x-axis and
z-axis positions of the object.
[0086] An optional method for dropping a sample plate off at a
desired location is to perform essentially the reverse of the
method described above for picking up a sample plate. In
particular, grasping mechanism 20 moves sample plate 25 into
contact with a push surface at the selected drop-off location such
that, e.g., several millimeters of clearance between spring stops
54 and the bodies of slideable interfaces 52 are produced. That is,
grasping mechanism 20 moves in the y-direction beyond the
programmed theoretical location of the push surface by, e.g., about
several millimeters. Examples of push surfaces are schematically
illustrated in, e.g., FIGS. 19 and 20. Thereafter, arms A and B of
grasping mechanism 20 are opened, releasing sample plate 25 from
pivot members 35. During this step, grasping mechanism 20 is not
moving in the y-direction so sample plate 25 remains in contact
with both stops 50 and the push surface at the drop-off location.
Subsequently, grasping mechanism 20 is moved away from sample plate
25 in the y-direction, relinquishing the clearance or over travel
in slideable interfaces 52. Grasping mechanism 20 continues to move
in the y-direction such that stops 50 pull away from contact with
sample plate 25, leaving sample plate 25 at the drop-off location
in contact with the push surface. The use herein of the terms
"pick-up" and "drop-off" or variations thereof for a location
refers to whether an object is being removed from or placed at that
location, respectively.
[0087] An apparatus and method for grasping and positioning an
object, such as the robotic gripper apparatus, are thus provided.
One skilled in the art will appreciate that the present invention
can be practiced by other than the preferred embodiments, which are
presented in this description for purposes of illustration and not
of limitation. It is noted that the practice of various equivalents
for the particular embodiments discussed in this description is
also within the scope of the invention.
[0088] While the foregoing invention has been described in some
detail for purposes of clarity and understanding, it will be clear
to one skilled in the art from a reading of this disclosure that
various changes in form and detail can be made without departing
from the true scope of the invention. For example, all the
techniques and apparatus described above may be used in various
combinations. All publications, patents, patent applications, or
other documents cited in this application are incorporated by
reference in their entirety for all purposes to the same extent as
if each individual publication, patent, patent application, or
other document were individually indicated to be incorporated by
reference for all purposes.
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