Accumulation control
Zones of an accumulation conveyor are controlled using a look ahead approach. The speed and article presence conditions of downstream and upstream zones are used to assess the condition of article flow in the neighborhood of a particular zone. The respective speeds of individual zones are then selected and implemented based on the assessment.
1. A method for controlling an accumulation conveyor, the accumulation conveyor comprising a plurality of zones, the method comprising:
receiving, at a controller, data indicating conditions for each zone of the plurality of zones; and
setting, at the controller, an operating speed for a first zone of the plurality of zones based on at least a condition of a downstream zone of the plurality of zones, the condition of the downstream zone being a speed of the downstream zone, wherein setting the operating speed comprises determining, at the controller, a potential speed of the first zone based on the speed of the downstream zone.
2. The method of claim 1 , wherein setting the operating speed for the first zone based on the condition of the downstream zone comprises setting, at the controller, the operating speed for the first zone based on determining, at the controller, whether the downstream zone is occupied by an article.
3. The method of claim 1 , wherein the speed of the downstream zone comprises a potential speed of the downstream zone.
4. The method of claim 1 , wherein setting the operating speed for the first zone based on the condition of the downstream zone comprises setting, at the controller, the operating speed for the first zone equal to the potential speed of the first zone.
5. The method of claim 4 , wherein setting the operating speed for the first zone equal to the potential speed of the first zone is based on a condition of an upstream zone.
6. The method of claim 1 , wherein setting the operating speed for the first zone based on the condition of the downstream zone comprises setting, at the controller, the operating speed for the first zone based on a deceleration rate of the first zone.
7. The method of claim 1 , wherein setting the operating speed for the first zone based on the condition of the downstream zone comprises setting, at the controller, the operating speed of the first zone based on a length of the first zone.
8. The method of claim 1 , wherein setting the operating speed for the first zone based on the condition of the downstream zone comprises setting, at the controller, the operating speed for the first zone based on a characteristic of an article being moved by the accumulation conveyor.
9. The method of claim 1 , wherein setting the operating speed for the first zone based on the condition of the downstream zone comprises setting, at the controller, the operating speed for the first zone equal to
(2| D LZ |*L LZ +( V LZ+1 ) 2 ) 1/2
where D LZ is a deceleration rate of the first zone, L LZ is a length of the first zone, V LZ+1 is the speed of the downstream zone.
10. The method of claim 9 , wherein the operating speed for the first zone is limited by a maximum speed for the first zone.
11. A material handling system, comprising:
an accumulation conveyor comprising a plurality of zones; and
a controller in communication with the accumulation conveyor to perform operations to:
receive data indicating conditions for each zone of the plurality of zones, and
set an operating speed for a first zone of the plurality of zones based on at least a condition of a downstream zone of the plurality of zones, the condition of the downstream zone being a speed of the downstream zone, wherein to set the operating speed comprises the controller to perform operations to determine a potential speed of the first zone based on the speed of the downstream zone.
12. The material handling system of claim 11 , wherein to set the operating speed for the first zone based on the condition of the downstream zone further comprises the controller to perform operations to set the operating speed for the first zone equal to the potential speed of the first zone.
13. The material handling system of claim 11 , wherein to set the operating speed for the first zone based on the condition of the downstream zone further comprises the controller to perform operations to set the operating speed for the first zone based on a deceleration rate of the first zone.
14. The material handling system of claim 11 , wherein to set the operating speed for the first zone based on the condition of the downstream zone further comprises the controller to perform operations to set the operating speed for the first zone based on a length of the first zone.
15. The material handling system of claim 11 , wherein to set the operating speed for the first zone based on the condition of the downstream zone further comprises the controller to perform operations to set the operating speed for the first zone based on a characteristic of an article being moved by the accumulation conveyor.
16. The material handling system of claim 11 , wherein to set the operating speed for the first zone based on the condition of the downstream zone further comprises the controller to perform operations to set the operating speed for the first zone equal to the potential speed based on a condition of an upstream zone.
17. The material handling system of claim 11 , wherein to set the operating speed for the first zone equal based on the condition of the downstream zone further comprises the controller to perform operations to set the operating speed for the first zone equal to
(2| D LZ |*L LZ +( V LZ+1 ) 2 ) 1/2
where D LZ is a deceleration rate of the first zone, L LZ is a length of the first zone, V LZ+1 is the speed of the downstream zone.
18. A controller comprising:
an interface to an accumulation conveyor;
at least one processor; and
a memory,
wherein the at least one processor is coupled to the memory and the interface and configured with processor-executable instructions to perform operations to:
receive data indicating conditions for each zone of the plurality of zones, and
set an operating speed for a first zone of the plurality of zones based on at least a condition of a downstream zone of the plurality of zones, the condition of the downstream zone being a speed of the downstream zone, wherein to set the operating speed comprises said at least one processor configured with processor-executable instructions to determine a potential speed of the first zone based on the speed of the downstream zone.
19. The controller of claim 18 , wherein the processor-executable instructions to perform operations to set the operating speed for the first zone based on the condition of the downstream zone further comprises said at least one processor configured with processor-executable instructions to set the operating speed for the first zone equal to the potential speed of the first zone.
20. The controller of claim 18 , wherein the processor-executable instructions to perform operations to set the operating speed of the first zone based on the speed of the downstream zone further comprises said at least one processor configured with processor-executable instructions to set the operating speed for the first zone based on a deceleration rate of the first zone.
21. The controller of claim 18 , wherein the processor-executable instructions to perform operations to set the operating speed of the first zone based on the speed of the downstream zone further comprises said at least one processor configured with processor-executable instructions to set the operating speed for the first zone based on a length of the first zone.
22. The controller of claim 18 , wherein the processor-executable instructions to perform operations to set the operating speed for the first zone based on the condition of the downstream zone further comprises said at least one processor configured with processor-executable instructions to set the operating speed for the first zone based on a characteristic of an article being moved by the accumulation conveyor.
23. The controller of claim 18 , wherein the processor-executable instructions to perform operations to set the operating speed for the first zone based on the condition of the downstream zone further comprises said at least one processor configured with processor-executable instructions zone, and based on the condition of the upstream zone, to set the operating speed for the first zone equal to the potential speed based on the condition of the upstream zone.
24. The controller of claim 18 , wherein the processor-executable instructions to perform operations to set the operating speed for the first zone based on the condition of the downstream zone further comprises said at least one processor configured with processor-executable instructions to set the operating speed for the first zone equal to
(2| D LZ |*L LZ +( V LZ+1 ) 2 ) 1/2
where D LZ is a deceleration rate of the first zone, L LZ is a length of the first zone, V LZ+1 is the speed of the downstream zone.