Pick and place

• US 8,565,912 B2
• Filed: 03/09/2012
• Issued: 10/22/2013
• Est. Priority Date: 09/11/2009
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Technology Limited (ABB Ltd.)
• Inventors: Wappling, Daniel, Murphy, Steve
• Primary Examiner(s): Crawford, Gene
• Assistant Examiner(s): LOGAN, KYLE O
• Application Number:
  US13/416,338
• Publication Number:
  US 20120165972A1
• Time in Patent Office: 592 Days
• Field of Search: 700/217
• US Class Current: 700/217
• CPC Class Codes: B25J 9/1687 Assembly, peg and hole, palletising, straight line, weaving pattern movement
• CPC Class Codes: G05B 19/4182 manipulators and conveyor only
• CPC Class Codes: G05B 2219/39102 Manipulator cooperating with conveyor
• CPC Class Codes: G05B 2219/40007 Optimize sequence of pick and place operations upon arrival of workpiece on conveyor
• CPC Class Codes: G05B 2219/40037 No incomplete containers allowed to exit on output conveyor
• CPC Class Codes: G05B 2219/40451 Closest, nearest arm, robot executes task, minimum travel time
• CPC Class Codes: G05B 2219/40554 Object recognition to track object on conveyor
• CPC Class Codes: G05B 2219/45048 Packaging
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A pick and place system including at least one input conveyor, at least one output conveyor, at least one pick and place robot and control circuitry. Available picking positions on an input conveyor at which a respective item can be picked are determined as well as available placing positions on an output conveyor at which a respective item can be placed. For the available picking positions and the available placing positions, a respective picking time and placing time is calculated, and the at least one robot is instructed to pick items at the picking positions and place the items at the placing positions in an order determined by the respective picking times and placing times.

Claims

1. A method in a pick and place system, the system comprising at least one input conveyor, at least one output conveyor, at least one pick and place robot and control circuitry, said control circuitry having a processing unit, the method comprising:

determining, in said processing unit, available picking positions on the at least one input conveyor at which a respective item is or will be within a working area of the at least one pick and place robot and can be picked by the robot,

determining, in said processing unit, available placing positions on the at least one output conveyor at which a respective item is or will be within a working area of the at least one pick and place robot and can be placed by the robot,

identifying, in said processing unit, groups of placing positions on the at least one output conveyor, each group having a respective number of placing positions, and wherein the determination of available placing positions includes,

for each group of placing positions, checking whether a placing position within the group is unavailable due to the placing position having exited, or will exit within a robot cycle time, a working area of the robot, and

if found to be unavailable, defining all placing positions within the group as unavailable,

calculating, in said processing unit, for the available picking positions and the available placing positions, a respective picking time by calculating a prediction of an instant in time when picking is to take place and a respective placing time by calculating a prediction of an instant in time when placing is to take place, and

instructing, via said processing unit, the at least one pick and place robot to pick items at the picking positions and place the items at the placing positions in an order determined by the respective picking times and placing times.

2. The method of claim 1, wherein the calculation of picking time differs depending on if the robot is waiting for input of a picking position or has received a picking position, and the calculation of placing time differs depending on if the robot is waiting for input of a placing position or has received a placing position.

3. The method of claim 1, wherein:

the determination of available picking positions comprises predicting picking positions based on a velocity of movement of the input conveyor and a performance measure of the pick and place system.

4. The method of claim 1, wherein:

the determination of available placing positions comprises predicting placing positions based on a velocity of movement of the output conveyor and a performance measure of the pick and place system.

5. The method of claim 1, wherein a performance measure of the pick and place system is a picking and placing cycle time.

6. The method of claim 1, wherein the robot is only instructed to pick an item and place the item when there is or will be an available placing position.

7. The method of claim 1, wherein the checking whether a placing position within the group is unavailable is performed only for groups having placing positions that are not already used.

8. The method of claim 1, wherein the system comprises a plurality of pick and place robots, each robot being associated with a respective output conveyor, the method comprising:

calculating, for each robot, a value representing a need for items to be placed, said need being quantified as the robot that can place an item fastest, or as the time period passed since a robot has placed an item, or whether or not the output conveyor is standing still, or the time period an output conveyor has been standing still,

for each item on the input conveyor, assign a specific robot to perform the picking and placing, the assignment being dependent on the value representing a need for items.

9. A computer-readable medium comprising software instructions that, when executed in a computer, perform a method in a pick and place system, the system comprising at least one input conveyor, at least one output conveyor, at least one pick and place robot and control circuitry, said computer being connected to said control circuitry and said control circuitry having a processing unit, the method comprising:

determining, in said processing unit, available picking positions on the at least one input conveyor at which a respective item is or will be within a working area of the at least one pick and place robot and can be picked by the robot,

determining, in said processing unit, available placing positions on the at least one output conveyor at which a respective item is or will be within a working area of the at least one pick and place robot and can be placed by the robot,

identifying, in said processing unit, groups of placing positions on the at least one output conveyor, each group having a respective number of placing positions, and wherein the determination of available placing positions includes,

for each group of placing positions, checking whether a placing position within the group is unavailable due to the placing position having exited, or will exit within a robot cycle time, a working area of the robot, and

if found to be unavailable, defining all placing positions within the group as unavailable,

calculating, in said processing unit, for the available picking positions and the available placing positions, a respective picking time by calculating a prediction of an instant in time when picking is to take place and a respective placing time by calculating a prediction of an instant in time when placing is to take place, and

instructing, via said processing unit, the at least one pick and place robot to pick items at the picking positions and place the items at the placing positions in an order determined by the respective picking times and placing times.

10. The computer-readable medium of claim 9, wherein the checking whether a placing position within the group is unavailable is performed only for groups having placing positions that are not already used.

11. The computer-readable medium of claim 9, wherein the system comprises a plurality of pick and place robots, each robot being associated with a respective output conveyor, the method comprising:

calculating, for each robot, a value representing a need for items to be placed, said need being quantified as the robot that can place an item fastest, or as the time period passed since a robot has placed an item, or whether or not the output conveyor is standing still, or the time period an output conveyor has been standing still,

for each item on the input conveyor, assigning a specific robot to perform the picking and placing, the assignment being dependent on the value representing a need for items.

12. A pick and place system comprising at least one input conveyor, at least one output conveyor, at least one pick and place robot and control circuitry having a processing unit, the system being configured such that it is capable of:

determining, in said processing unit, available picking positions on the at least one input conveyor at which a respective item is or will be within a working area of the at least one pick and place robot and can be picked by the robot,

determining, in said processing unit, available placing positions on the at least one output conveyor at which a respective item is or will be within a working area of the at least one pick and place robot and can be placed by the robot,

identifying, in said processing unit, groups of placing positions on the at least one output conveyor, each group having a respective number of placing positions, and wherein the determination of available placing positions includes,

for each group of placing positions, checking whether a placing position within the group is unavailable due to the placing position having exited, or will exit within a robot cycle time, a working area of the robot, and

if found to be unavailable, defining all placing positions within the group as unavailable,

calculating, in said processing unit, for the available picking positions and the available placing positions, a respective picking time by calculating a prediction of an instant in time when picking is to take place and a respective placing time by calculating a prediction of an instant in time when placing is to take place, and

instructing, via said processing unit, the at least one pick and place robot to pick items at the picking positions and place the items at the placing positions in an order determined by the respective picking times and placing times.

13. The pick and place system of claim 12, wherein the checking whether a placing position within the group is unavailable is performed only for groups having placing positions that are not already used.

14. The pick and place system of claim 12 further comprising a plurality of pick and place robots, each robot being associated with a respective output conveyor, wherein the system is configured such that it is capable of:

calculating, for each robot, a value representing a need for items to be placed, said need being quantified as the robot that can place an item fastest, or as the time period passed since a robot has placed an item, or whether or not the output conveyor is standing still, or the time period an output conveyor has been standing still,

for each item on the input conveyor, assigning a specific robot to perform the picking and placing, the assignment being dependent on the value representing a need for items.

15. A pick and place robot configured to operate in a pick and place system, and comprising a processing unit that receives information and performs calculations and procedures according to a method in the pick and place system, the system comprising at least one input conveyor, at least one output conveyor, at least one pick and place robot and control circuitry, the method comprising:

determining available picking positions on the at least one input conveyor at which a respective item is or will be within a working area of the at least one pick and place robot and can be picked by the robot,

determining available placing positions on the at least one output conveyor at which a respective item is or will be within a working area of the at least one pick and place robot and can be placed by the robot,

identifying groups of placing positions on the at least one output conveyor, each group having a respective number of placing positions, and wherein the determination of available placing positions includes,

for each group of placing positions, checking whether a placing position within the group is unavailable due to the placing position having exited, or will exit within a robot cycle time, a working area of the robot, and

if found to be unavailable, defining all placing positions within the group as unavailable,

calculating, for the available picking positions and the available placing positions, a respective picking time by calculating a prediction of an instant in time when picking is to take place and a respective placing time by calculating a prediction of an instant in time when placing is to take place, and

instructing the at least one pick and place robot to pick items at the picking positions and place the items at the placing positions in an order determined by the respective picking times and placing times.

16. The pick and place robot of claim 15, wherein the checking whether a placing position within the group is unavailable is performed only for groups having placing positions that are not already used.

17. The pick an place robot of claim 15, wherein the system comprises a plurality of pick and place robots, each robot being associated with a respective output conveyor, the method comprising:

calculating, for each robot, a value representing a need for items to be placed, said need being quantified as the robot that can place an item fastest, or as the time period passed since a robot has placed an item, or whether or not the output conveyor is standing still, or the time period an output conveyor has been standing still,

for each item on the input conveyor, assigning a specific robot to perform the picking and placing, the assignment being dependent on the value representing a need for items.