The invention generally relates to robotic systems and relates in particular to articulated arms that include end effectors that provide a vacuum source for object acquisition or gripping.
Such vacuum grippers exist in many configurations in the prior art. Generally, such devices use compressed air to generate a vacuum by use of a Venturi pump. The vacuum is then presented at the object to be acquired through any one of a variety of interfaces.
One type of interface is a single large open port, which maximizes the suction pressure from the vacuum and is thus well equipped to acquire heavy objects or those packaged in loose plastic. This configuration is commonly referred to as a bag type gripper.
Another type of interface is an array of smaller ports, each of which may have integrated flow control (due to their small hole size) designed to close or reduce them if they are not making contact with the object to be acquired. By closing unsealed ports, the suction pressure at ports that have successfully mated with the object to be acquired should be maximized. This approach provides flexibility in object acquisition since not all ports need to mate with an object in order to successfully acquire it. This flow control is generally accomplished by means of metering (or making the ports small enough that the resulting leakage from an unsealed port is immaterial).
In other vacuum gripper systems, integrated check valves may be used in port chambers that contact the environment. Typically, such devices include seals around the vacuum ports at the surface that meets the object to be acquired. This approach, while being more mechanically complicated, has the advantage of stronger overall suction force, since unsealed ports truly close at the opening, rather than just restricting leakage flow. For single large ports, a large suction cup or foam ring is used. For the array of ports configuration, an array of suction cups or a foam pad with holes for each of the individual ports are commonly used.
In some vacuum gripper systems, a set of actuated valves is provided for the air flowing through the gripper; a valve on the compressed air input allows for shutting the vacuum on and off, allowing the gripper to drop an object. This approach, however, is slow due to time constants of air pressure equalization within the gripper body. The speed of release is dramatically increased by adding a second controlled valve to the exhaust port of the vacuum generator; by closing this valve, compressed air is diverted through the gripper body and out the vacuum ports, effectively blowing the acquired object off of the gripper surface quickly.
The vacuum grippers in the prior art are generally designed for a specific object or material in a predetermined orientation. The specific gripper style and configuration is chosen to optimize for a particular acquisition problem (for instance, palletizing and de-palletizing a particular size/type of cardboard cartons). Such grippers are not at all well suited to a wide array of objects in non-predetermined orientations.
Further, in such vacuum gripper systems, software systems and algorithms are provided that are developed around the concept of maximizing speed and efficiency of abort/retry cycles for robotic manipulators acquiring objects. These algorithms have been focused in some applications on heavily instrumented multiple-finger mechanical grasping manipulators. The algorithms use the data from joint angles and motor power to determine how well an object is grasped and immediately retry if the grasp is not good enough.
In many such vacuum gripper systems, abort/retry techniques with vacuum grippers are unsophisticated. These techniques generally consist of applying vacuum, lifting the gripper, and looking at coarse flow rate or weight sensors to determine whether an object has been acquired; if it has not, the gripper is placed back on the object and acquisition is re-attempted. This is due largely to two reasons: 1) most currently deployed vacuum gripping systems are customized so heavily for the material being acquired that acquisition failures are rare, resulting in no real need for rapid abort and retry cycles, and 2) no vacuum grippers exist with the type of sophisticated instrumentation present in, for instance, a multi-fingered grasping type end effector. The result is that existing abort/retry algorithms cannot obtain from a vacuum gripper the information they need to be able to operate.
There remains a need, therefore, for an improved vacuum gripper for use in an articulated arm that provides improved performance in acquiring a wide variety of known and unknown objects.
In accordance with an embodiment, the invention provides an end effector for an articulated arm. The end effector includes a valve assembly including a plurality of supply channels, each supply channel including a supply conduit, a pressure sensor in fluid communication with the supply conduit, and a supply conduit plug. The supply conduit is in fluid communication with a vacuum source. During use, each supply conduit is either at vacuum such that the pressure within the supply conduit is substantially at a vacuum pressure, or is at a pressure that is substantially higher than vacuum pressure because the supply conduit plug has moved to block a portion of the supply conduit. The pressure sensor of each supply conduit provides a pressure sensor signal responsive to whether the pressure in the conduit is either substantially at vacuum or is at a pressure that is substantially higher than vacuum.
In accordance with another embodiment, the end effector includes a valve assembly including a plurality of supply channels, each supply channel including a supply conduit, a pressure sensor in fluid communication with the supply conduit, and a supply conduit plug. The supply conduit is in fluid communication with a vacuum source. During use, each supply conduit is either at vacuum such that the pressure within the supply conduit is substantially at a vacuum pressure, or is at a pressure that is substantially higher than vacuum pressure because the supply conduit plug has moved to block a portion of the supply conduit. The pad includes a plurality of defined apertures, each of which is aligned with a respective supply conduit of the valve assembly, and the plurality of defined apertures in the pad include at least a first aperture and a second plurality of apertures, and wherein the at least the first aperture is centrally located with respect to the second plurality of apertures
In accordance with a further embodiment, the invention provides a method of providing a vacuum source to an end effector. The method includes the steps of providing within the end effector a valve assembly including a plurality of supply channels, each supply channel including a supply conduit, a pressure sensor in fluid communication with the supply conduit, and a supply conduit plug, providing a vacuum source in fluid communication with the supply conduit, permitting the supply conduit to be at a pressure that is substantially higher than vacuum pressure when the associated supply channel is not engaged with an object, permitting the supply conduit to be at vacuum such that the pressure within the supply conduit is substantially at a vacuum pressure when the supply channel is engaged with an object, and providing a pressure sensor signal responsive to whether the pressure in the conduit is either substantially at vacuum or is at a pressure that is substantially higher than vacuum.
The following description may be further understood with reference to the accompanying drawings in which:
The drawings are shown for illustrative purposes only.
In accordance with various embodiments, the invention provides a new instrumented hybrid-modality vacuum gripper system that has three main features as follows. First, the system provides hybrid modality. The gripping surface is a unique design that incorporates the advantages of both the single large port configuration and the array of controlled ports configuration of vacuum gripper, resulting in a single device that is more effective than either previously existing configuration. Second, the system provides unique instrumentation. The gripper is mounted to the end effector using a load cell array, such that controlling software has precise knowledge of weights and torques being applied to the gripper by the acquired object. Each individual vacuum port in the gripping surface is also instrumented such that controlling software has precise knowledge of how well each individual port is gripping the object that is being acquired. Third, the novel software and algorithms provide that presented sensor data may be used to maximize the efficiency of abort/retry cycles using this instrumented gripper. The general approach of hybrid modality, instrumentation, and algorithms applied to vacuum grippers is illustrated, in part, by the following examples.
The instrumented gripper assembly in accordance with an embodiment is shown in
The vacuum generation and control is provided by moving compressed air through a control valve to a Venturi pump, which creates a vacuum for the gripper to distribute to the gripping surface. A second valve on the output of the Venturi pump allows one to blow-off acquired objects, as described above.
The plenum block is provided below the Venturi pump, and the plenum block distributes the generated vacuum to each of the individual ports in series by means of a channels that are machined into the block. This approach minimizes the vacuum pressure required to check any individual port's control valve.
With further reference to
The top opening 32 mates to the plenum, thus providing a vacuum to the check valve chamber 34. The bottom opening 30 delivers the vacuum through the screen plate 18 to the bottom surface of the gripper 20, and thence to the object being acquired. The plug 36 in each check valve chamber is a plastic ball, of such a size and weight that if the bottom opening is open to atmosphere (i.e., not making contact with an object to be acquired) and a vacuum is applied to the top opening, the plastic ball 36 will be pulled by the vacuum up to the top opening, where it will seat firmly against the chamfer there and effectively seal that particular check valve port. By using these types of ports, it is ensured that any ports that are not actually making contact with an object to be acquired are sealed and not bleeding off vacuum pressure.
The screen plate 18 mounts to the bottom of the check valve plate 16. It consists of a thin metal piece with openings that mate to each check valve. These openings are of such a size and shape (trefoil shape is used here) as to allow the ball 36 to sit on the opening without falling out, and without sealing the lower opening 30. In this way, when the port is not making contact with an object to be acquired, air will flow through this opening, lifting the ball to the top of the chamber and sealing off that particular port. When the port is making contact with an object, the vacuum will be present in the chamber 34 and will hold the object against the surface 22 of the gripper 20.
Of significance in this design is the incorporated printed circuit board 40. The check valve plate is split into two pieces, top and bottom as shown in
When a vacuum is applied to the gripper, ports that are contacting the object being acquired will remain unchecked, meaning that the sensors in those ports will read vacuum pressure (<<1 atmosphere). Any ports that are not contacting the object will check, meaning the pressure in the bottom of the chamber will be equivalent to atmospheric pressure. By reading all of the sensors, the software system will know exactly which ports are checked and which are making solid contact (and thus providing gripping force) to the object being acquired. Even once an object has been acquired, if it starts to “peel off” of the gripper, or falls off completely, the sensor readings will change accordingly, allowing the software system to know this in real time.
The gripper is circular at the gripping surface, as shown in
The effect of this arrangement is a hybrid modality gripper combining the benefits of the single-large-port (or “bag”) configuration and the array-of-controlled-ports configuration. The ports 58 in the middle (as shown in
The top opening 72 mates to the plenum, thus providing a vacuum to the check valve chamber 70. The bottom openings 58 deliver the vacuum through the screen plate 18 to the bottom surface of the gripper 20 in the inner area 50 as a common group of apertures, and thence to the object being acquired. Again, the plug 76 in the check valve chamber is a plastic ball, of such a size and weight that if the bottom opening is open to atmosphere (i.e., not making contact with an object to be acquired) and a vacuum is applied to the top opening, the plastic ball 76 will be pulled by the vacuum up to the top opening, where it will seat firmly against the chamber there and effectively seal that particular check valve port as shown in
This hybrid modality allows for successful acquisition of a much broader spectrum of objects than either prior type of vacuum gripper by itself. Heavy objects in plastic bags (e.g., a bag of oranges) typically cannot be acquired by standard port-array type vacuum grippers, but only by single large port type grippers; the central port grouping on the novel gripper presented here can acquire these objects. Another example is a bottle of shampoo standing upright; a typical single large port type gripper will be too large to seal to the top of the cap, and thus will not acquire the object. The novel gripper here can use a single port from the outer ring to seal to the shampoo cap; all other ports, including the central group, will check, allowing this device to successfully acquire the object. In other embodiments, different vacuum pressures may be applied to the inner set of apertures as compared to the outer set of apertures in a variety of ways, including for example, restricting air flow in the outer set of apertures.
This combination of power and flexibility is unique and powerful. By combining the benefits of multiple configurations, the result is greatly reduced or eliminated need for tool changing, along with the associated cost and time.
In accordance with certain embodiments, the invention further provides a system for providing high flow vacuum control to an end effector of an articulated arm. In accordance with various embodiments, the invention provides a dynamic high flow gripping system, and may optionally include a mechanism to select between the high flow source and a high vacuum source, depending on the application. High flow vacuum systems of the invention may therefore optionally be used with high vacuum sources.
The system, for example, may include a first vacuum source for providing a first vacuum pressure with a first maximum air flow rate (to for example, the inner area 50), and a second vacuum source for providing a second vacuum pressure with a second maximum air flow rate (to for example, the outer area 52). In certain embodiments, the second vacuum pressure is higher than the first vacuum pressure and wherein the second maximum air flow rate is greater than the first maximum air flow rate. The reverse is also possible in other applications. The flow rates are characterized as maximum air flow rates because, when an object is engaged at an end effector, the flow rate may drop significantly. The high flow source may be used together with a high vacuum source, or as a single source.
In particular,
The vacuum pressure provided by the ejector 124 may be, for example, at least about 90,000 Pascals below atmospheric and the vacuum pressure provided by the blower 128 may be only no more than about 25,000 Pascals below atmospheric in some examples, and no more than about 50,000 Pascals below atmospheric in other examples. The vacuum pressure provided by the blower 128 is therefore higher than the vacuum pressure provided by the ejector 124. The maximum air flow rate of the ejector may be, for example, no more than about 5 cubic feet per minute (e.g., 1-2 cubic feet per minute), and the maximum air flow rate of the blower may be, for example at least about 100 cubic feet per minute (e.g., 130-140 cubic feet per minute).
In accordance with certain embodiments, therefore, end effectors of the invention may include a central region of a gripper surface that provides high flow gripping. In further embodiments, the surface at the central region of the gripper may include a specialized opening cover for use with a high flow vacuum gripper. In particular and as shown in
The compliant foam on the surface 144 contacts the object to be acquired, giving the gripper some compliance while also acting to seal the aperture around the object as the foam is compressed and the high flow vacuum is applied. The aperture cover therefore allows a high flow gripper to effectively pick up long narrow objects with an easy to attach cover that may be held in a tool changer and added or removed from the gripper autonomously during real-time operation
A system is therefore provided in an embodiment, for providing vacuum control to an end effector of an articulated arm, where the system includes a vacuum source for providing a vacuum pressure at a flow rate to the end effector, and the end effector includes a cover that includes an opening that varies significantly in radius from a center of the cover. The opening may include finger openings that extend radially from the center of the opening. The opening may be generally star shaped or asterisk shaped. The cover may include compliant foam on a distal side of the cover that engages an object to be grasped, and an air flow resistant material on a proximal side of the cover. The vacuum pressure may be no more than about 50,000 Pascals below atmospheric, and the air flow rate may be at least about 100 cubic feet per minute.
The invention therefore provides a system for providing vacuum control to an end effector of an articulated arm, where the system includes a vacuum source for providing a vacuum pressure at a flow rate to the end effector, and the end effector includes a cover including an air flow resistant material on a proximal side of the cover and a compliant material on a distal side of the cover for contacting objects to be grasped. The cover may include an opening that varies significantly in radius from a center of the cover, and the opening may include finger openings that extend radially from the center of the opening. The opening may be generally star shaped or asterisk shaped. The cover may be formed of a compliant material and include compliant foam on a distal side of the cover that engages an object to be grasped, and the cover may include an air flow resistant material on a proximal side of the cover. The vacuum pressure may be no more than about 25,000 Pascals or 50,000 Pascals below atmospheric, and the air flow rate may be at least about 100 cubic feet per minute.
Covers with other types of openings are shown in
The gripper assembly may be mounted to the end of a wide variety of 4- or 6-axis robotic arms. The mounting assembly 200 incorporates load cells, as shown in
The system therefore, does not require the use of sophisticated software algorithms that use probabilistic and predictive processes to maximize speed and efficiency of acquisition/failure/abort/retry cycles with multi-fingered hand-type grasping end effectors. These algorithms rely on precise data about joint angles and motor speeds/currents/torques as well as image data from 2D or 3D camera systems to know whether or not an acquisition has been successful and plan a retry if necessary. Because vacuum grippers have previously lacked any type of similarly sophisticated sensing, and because previous applications have been limited and highly controlled, these algorithms have not been applied previously to vacuum gripping situations.
The novel gripper described here provides such data using inexpensive sensors (load cells and MEMS barometers). When the gripper is placed on an object and the vacuum is enabled, the software control system will immediately have a map of which ports are providing suction to the object and which are checked closed. With a priori knowledge of the object (from 2D/3D imaging and database matching, for instance), the SW will be able to calculate a success percentage for object acquisition.
If the percentage is below a threshold, the control system can shut off vacuum and reposition the gripper to try again quickly without having to actually attempt and fail at acquisition first. This will greatly enhance retry speed.
If the percentage is above some threshold, the control system can raise the gripper. At this point, the data from the load cell array will begin to tell the control system whether or not the object weight is being lifted, and at what position and torque. As the object is being moved, the load cell and port pressure data will also warn the control system if the acquisition is failing and the object is going to fall, allowing the control system to take appropriate action.
This data will provide the software control system a real time picture of where, how, and how well an object is acquired, from before the gripper has even been moved all the way through object delivery and release. This data can be used by a software control system as input for efficient abort/retry algorithms previously only used by more sophisticated manipulators.
The instrumented hybrid-modality vacuum gripper presented here therefore, combines the benefits of prior vacuum gripper configurations into a single device, at the same time integrating sensors that provide the kind of detailed acquisition data needed to enable advanced abort/retry efficiency software algorithms previously reserved for more sophisticated multi-finger type grippers. The result is a single inexpensive end effector that can be used to rapidly and efficiently acquire and move a very broad spectrum of object types, sizes, weights, and packaging types, in a variety of orientations.
Those skilled in the art will appreciate that numerous modifications and variations may be made to the above disclosed embodiments with departing from the spirit and scope of the present invention
The present application is a continuation of U.S. patent application Ser. No. 16/830,574, filed Mar. 26, 2020; which is a continuation of U.S. patent application Ser. No. 16/391,980, filed Apr. 23, 2019, now U.S. Pat. No. 10,647,005, issued May 12, 2020; which is a continuation of U.S. patent application Ser. No. 15/961,275, filed Apr. 24, 2018, now U.S. Pat. No. 10,300,612, issued May 28, 2019; which is a divisional of U.S. patent application Ser. No. 15/248,379, filed Aug. 26, 2019, now U.S. Pat. No. 9,999,977, issued Jun. 19, 2018; which claims priority to U.S. Provisional Patent Application Ser. No. 62/210,246, filed Aug. 26, 2015, the disclosure of which are hereby incorporated by reference in their entireties.
Number | Name | Date | Kind |
---|---|---|---|
2853333 | Littell | Sep 1958 | A |
3005652 | Helm | Oct 1961 | A |
3195941 | Morey | Jul 1965 | A |
3637249 | Kuhl et al. | Jan 1972 | A |
4389064 | Laverriere | Jun 1983 | A |
4412775 | Molitor et al. | Nov 1983 | A |
4495968 | Kist | Jan 1985 | A |
4557659 | Scaglia | Dec 1985 | A |
4880358 | Lasto | Nov 1989 | A |
5024575 | Anderson | Jun 1991 | A |
5752729 | Crozier et al. | May 1998 | A |
5865487 | Gore et al. | Feb 1999 | A |
5890553 | Bar-Cohen | Apr 1999 | A |
6015174 | Raes et al. | Jan 2000 | A |
6244640 | Le Bricquer et al. | Jun 2001 | B1 |
6397876 | Goldern et al. | Jun 2002 | B1 |
6817639 | Schmalz et al. | Nov 2004 | B2 |
7076335 | Seemann | Jul 2006 | B2 |
7140389 | Schnatterer et al. | Nov 2006 | B2 |
7263890 | Takahashi | Sep 2007 | B2 |
7618074 | Zimmer | Nov 2009 | B2 |
7637548 | Fukano et al. | Dec 2009 | B2 |
7677622 | Dunkmann et al. | Mar 2010 | B2 |
8070203 | Schaumberger | Dec 2011 | B2 |
8096598 | Perlman | Jan 2012 | B2 |
8132835 | Ban et al. | Mar 2012 | B2 |
8267386 | Schaaf et al. | Sep 2012 | B2 |
8662861 | Tell | Mar 2014 | B2 |
8777284 | Schaller et al. | Jul 2014 | B2 |
9011407 | Harig | Apr 2015 | B2 |
9061868 | Paulsen et al. | Jun 2015 | B1 |
9656813 | Dunkmann et al. | May 2017 | B2 |
9999977 | Wagner | Jun 2018 | B2 |
10058896 | Hicham et al. | Aug 2018 | B2 |
10118300 | Wagner et al. | Nov 2018 | B2 |
10300612 | Wagner | May 2019 | B2 |
10315315 | Wagner et al. | Jun 2019 | B2 |
10399236 | Wagner et al. | Sep 2019 | B2 |
10647005 | Wagner | May 2020 | B2 |
11185996 | Wagner | Nov 2021 | B2 |
20010013434 | Hopkins | Aug 2001 | A1 |
20010045755 | Schick et al. | Nov 2001 | A1 |
20030038491 | Schmalz et al. | Feb 2003 | A1 |
20030164620 | Schmalz et al. | Sep 2003 | A1 |
20060242785 | Cawley et al. | Nov 2006 | A1 |
20080179224 | Van Bossuyt | Jul 2008 | A1 |
20090019818 | Gilmore et al. | Jan 2009 | A1 |
20130129464 | Regan et al. | May 2013 | A1 |
20130232918 | Lomerson, Jr. | Sep 2013 | A1 |
20130277999 | Schaller et al. | Oct 2013 | A1 |
20140005831 | Naderer et al. | Jan 2014 | A1 |
20150081090 | Dong | Mar 2015 | A1 |
20150298316 | Accout et al. | Oct 2015 | A1 |
20150328779 | Bowman et al. | Nov 2015 | A1 |
20150375401 | Dunkmann et al. | Dec 2015 | A1 |
20160161055 | Bain | Jun 2016 | A1 |
20160271805 | Kuolt et al. | Sep 2016 | A1 |
20170050315 | Henry et al. | Feb 2017 | A1 |
20170057091 | Wagner et al. | Mar 2017 | A1 |
20170080571 | Wagner et al. | Mar 2017 | A1 |
20170087718 | Wagner et al. | Mar 2017 | A1 |
20170087731 | Wagner et al. | Mar 2017 | A1 |
20170120455 | Wagner et al. | May 2017 | A1 |
20170121113 | Wagner et al. | May 2017 | A1 |
20170136632 | Wagner et al. | May 2017 | A1 |
20170225330 | Wagner et al. | Aug 2017 | A1 |
Number | Date | Country |
---|---|---|
1367729 | Sep 2002 | CN |
101323396 | Dec 2008 | CN |
203680306 | Jul 2014 | CN |
104181723 | Dec 2014 | CN |
3810989 | Aug 1989 | DE |
10121344 | Jul 2002 | DE |
102007054867 | May 2009 | DE |
102011115951 | Apr 2013 | DE |
1348873 | Dec 2004 | EP |
1671906 | Jun 2006 | EP |
1256421 | Jan 2008 | EP |
2014587 | Jan 2009 | EP |
2708335 | Mar 2014 | EP |
2960024 | Dec 2015 | EP |
H6155399 | Mar 1986 | JP |
H0769470 | Mar 1995 | JP |
2010201536 | Sep 2010 | JP |
2014161549 | Sep 2014 | WO |
2017044632 | Mar 2017 | WO |
Entry |
---|
Anver Corporation: Vacuum Tube Lifting Systems, Nov. 22, 2004 (http://www.jrgindustries.com/assets/anver.pdf). |
Communication pursuant to Article 94(3) EPC issued by the European Patent Office in related European Patent Application No. 16763400.5 dated Jul. 12, 2021, 4 pages. |
Communication pursuant to Rules 161(1) and 162 EPC issued by the European Patent Office dated Apr. 5, 2018 in related European Patent Application No. 16763400.5, 3 pages. |
Engineering ToolBox, (2008). Vacuum Pipes—Veocities, [online] Available at https://www.engineeringtoolbox.com/vacuum-pipes-air-velocity-d 1195.html. |
Examiner's Report issued by the Innovation, Science and Economic Development Canada dated Feb. 28, 2019, in related Canadian Patent Application No. 2,996,868, 3 pages. |
Examiner's Report issued by the Innovation, Science and Economic Development Canada dated Dec. 10, 2019, in related Canadian Patent Application No. 2,996,868, 3 pages. |
Final Office Action issued by the U.S. Patent and Trademark Office in related U.S. Appl. No. 16/830,574 dated Mar. 25, 2021, 9 pages. |
First Office Action, and its English translation, issued by the China National Intellectual Property Administration in related Chinese Patent Application No. 201680061046.1 dated Jul. 30, 2020, 26 pages. |
International Preliminary Report on Patentability issued by the International Bureau of WIPO dated Feb. 27, 2018, in related international application No. PCT/US2016/048968, 9 pages. |
International Search Report and Written Opinion issued by the International Searching Authority dated Nov. 11, 2016 in related International Application No. PCT/US2016/048968. |
Non-Final Office Action issued by the U.S. Patent and Trademark Office dated Jan. 18, 2018 in related U.S. Appl. No. 15/248,379, 6 pages. |
Non-Final Office Action issued by the U.S. Patent and Trademark Office dated Sep. 20, 2019 in related U.S. Appl. No. 16/391,980, 5 pages. |
Number | Date | Country | |
---|---|---|---|
20220055231 A1 | Feb 2022 | US |
Number | Date | Country | |
---|---|---|---|
62210246 | Aug 2015 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 15248379 | Aug 2016 | US |
Child | 15961275 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 16830574 | Mar 2020 | US |
Child | 17504977 | US | |
Parent | 16391980 | Apr 2019 | US |
Child | 16830574 | US | |
Parent | 15961275 | Apr 2018 | US |
Child | 16391980 | US |