WO2011066856A1

WO2011066856A1 - A method, apparatus, computer program and computer program product for controlling a crane set

Info

Publication number: WO2011066856A1
Application number: PCT/EP2009/066262
Authority: WO
Inventors: Alf Isaksson; Stefan Israelsson Tampe; Guido Sand
Original assignee: Abb Research Ltd
Priority date: 2009-12-02
Filing date: 2009-12-02
Publication date: 2011-06-09

Abstract

It presented a method for controlling a crane set of at least two automated container cranes. The method comprises the steps of : determining that a delayed completion time of a movement operation of a first crane of the crane set allows the completion time of an overall plan of movements to remain unaffected; and effecting the movement operation with a completion time being later than the originally planned completion time, such that energy consumption and/or power consumption for the crane set is reduced. A corresponding apparatus and computer program and product are also presented.

Description

A METHOD, APPARATUS, COMPUTER PROGRAM AND COMPUTER PROGRAM PRODUCT FOR CONTROLLING A CRANE SET

FIELD OF INVENTION

The invention relates generally to control of at least two automated cranes .

BACKGROUND

A large part of traded goods in the world is transported by sea using container ships. To support such shipping, ports must support loading, unloading and storing of containers. To make such operations efficient, ports often deploy automated container cranes .

The automated container cranes perform movements

according to movement orders. It is realised that a large amount of cranes require a significant amount of energy and electrical power. It would therefore be desirable to reduce the amount of energy or power required for automated cranes .

SUMMARY

An object of the invention is to reduce energy and/or power requirements for automated cranes while still not affecting an overall plan completion time.

According to a first aspect of the invention, it is presented a method for controlling a crane set of at least two automated container cranes . The method

comprises the steps of: determining if a delayed

completion time of a movement operation of a first crane of the crane set allows a completion time of an overall plan of movements to remain unaffected; and effecting, when the determining step provides an affirmative result, the movement operation with a completion time of the movement operation being later than the originally planned completion time of the movement operation, such that energy consumption and/or power consumption for the crane set is reduced.

This allows energy usage to be reduced without affecting the completion time of the overall plan. It is to be noted that this may affect different movement operations of different cranes at different points in time. For example, in the beginning of an overall plan, crane A could be on a critical path, whereby a crane B movement can be delayed to reduce energy consumption, while at a later stage, crane B could be on a critical path, whereby a crane A movement can be delayed.

By reducing power usage, the crane set uses a smaller current and can in some cases be configured to use a smaller peak electrical current from the grid. The step of determining may comprise determining that, due to an interdependency between plans for the first crane and a second crane, a delayed completion time of the movement operation of the first crane allows the end time of the overall plan of movements to remain

unaffected.

The step of effecting the movement may control

acceleration to reduce energy consumption and/or

consumption. The step of effecting the movement may reduce movement speed to reduce energy consumption and/or power

consumption.

The step of effecting the movement times may comprise timing a lifting of the load of the first crane to correspond in time to when the load of another crane of the crane set is lowered. The lowering is also known as set-down and the lifting is also known as pick-up. This can reduce power usage which reduces the electrical current drawn from the power grid.

The step of effecting the movement times may comprise delaying a start time of the movement operation of the first crane.

The determining step and the effecting step may be repeated for each crane in the crane set.

The method may further comprise the step, prior to the step of determining, of: determining an overall plan as a compromise between completions time of the overall plan and energy usage and/or power consumption of the overall plan. It is to be noted that the determining an overall plan is to be construed either as modifying an existing plan or creating a new plan.

The step of determining an overall plan may comprise using weighting factors for completion time of the overall plan, and energy usage and/or power consumption of the overall plan, respectively.

The method may further comprise the steps of: presenting at least two options for an overall plan, each option comprising a completion time of the overall plan and an energy usage and/or power consumption indication of the overall plan, and receiving an input for a selected one of the options . A second aspect of the invention is an apparatus for controlling a crane set of at least two automated container cranes, the apparatus comprising: determiner arranged to determine that a delayed completion time of a movement operation of a first crane of the crane set allows the completion time of an overall plan of

movements to remain unaffected; and a movement controller effecting the movement operation with a completion time being later than the originally planned completion time such that energy consumption and/or power consumption for the crane set is reduced.

The determiner may be arranged to determine that, due to an interdependency between plans for the first crane and a second crane, a delayed completion time of the movement operation of the first crane allows the end time of the overall plan of movements to remain unaffected.

The movement controller may be arranged to control acceleration to reduce energy consumption and/or power consumption .

The movement controller may be arranged to reduce movement speed to reduce energy consumption and/or power consumption.

The movement controller may be arranged to adjust timing of a lifting of the load of the first crane to correspond in time to when the load of another crane of the crane set is lowered.

The movement controller may be arranged to delay a start time of the movement operation of the first crane. The apparatus may further comprise: an output device arranged to present at least two options for an overall plan, each option comprising a completion time and an energy usage and/or power consumption indication, and an input device arranged to receive an input for a selected one of the options.

A third aspect of the invention is a computer program for a crane controller, the computer program comprising computer program code which, when run on the crane controller, causes the crane controller to perform the steps according to the first aspect.

A fourth aspect of the invention is a computer program product comprising a computer program according to the third aspect and a computer readable means on which the computer program is stored. It is to be noted that any feature of the first, second, third and fourth aspects may, where appropriate, be applied to any other aspects of these aspects.

Analogously any feature of the fifth, sixth, seventh, and eighth aspects may, where appropriate, be applied to any other aspects of these aspects

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF DRAWINGS

The invention is now described, by way of example, with reference to the accompanying drawings, in which:

Fig 1 is a schematic diagram illustrating en embodiment of the present invention in a container port,

Fig 2a is a schematic diagram illustrating a relatively small number of movement operations of the system of Fig 1,

Fig 2b is a schematic diagram illustrating a relatively large number of movement operations of the system of Fig 1,

Fig 3 is a schematic graph illustrating time usage of the cranes for the movement operations of Fig 2b,

Fig 4 shows one example of a computer program product 100 comprising computer readable means, and

Fig 5 is a flow chart illustrating a method according to one embodiment . DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many

different forms and should not be construed as limited to the embodiments set forth herein; rather, these

embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

Fig 1 shows a port 11 provided with a port logistics system 8 controlling all movements of crane sets in the port. Ships 2 arrive to unload or load containers 1, and the containers are stored, in this embodiment, in four storage blocks 10. Each storage block 10 is served by two cranes 5, where the two cranes for a storage block 10 make up a crane set. The port logistics system 8 controls the cranes that unload/ load the ships through a

communication bus 3, and an unloaded container is brought from a ship via a transport rail 4 to a storage block 10 selected by the port logistics system 8. Cranes 5 that are dedicated to a storage block 10, and controlled by the port logistics system 8, move the unloaded container into a position as ordered within the storage block 10. A container that is going to be loaded onto a ship is collected by the cranes 5 and moved to the transport rail 4 to be transported to the ship 2. The port logistics system issues orders to each crane and these orders are arranged in a queue for each crane. The same applies when a truck 6 loads or unloads a container on the lower side of the blocks 7.

Fig 2 schematically shows in some more detail how two cranes 5a serve a storage block 10. A co-ordinate system has been overlaid to make references to the movement operations clear. References are made herein in the form of [x, y] . As an example, the top container of position [1, 2] is to be moved to position [3, 8]. However, the upper crane 5a does not reach position [1, 2] and the lower crane 5b does not reach position [3, 8]. Hence, in this example, the lower crane 5b is first ordered, in a first movement operation 11a, to move the top-most container of position [1, 2] to position [3, 3]. This allows the upper crane 5a, in a second movement operation lib, to move the container from position [3, 3] to position [3, 8], allowing the container to be

transferred to loading cranes using the transport rail 4.

Note that during the second movement operation lib, the lower crane is free to perform other movement operations . Since the containers can be stacked in the z-dimension (not shown) , it is easy to understand that moving a particular container to be shipped out can require a large number of movement operations. Loading a ship with a significant number of containers thus results in an overall plan which can include hundreds of movement operations. Moreover, there are similar overall plans when trucks 6 are unloaded. During times when there is no unloading or loading of containers, the cranes can perform optimisation, where containers are reordered to allow ship loading with fewer movement operations. With all these overall plans, regardless whether they are overall plans for ship loading, truck unloading or reordering, there are some limitations . Firstly, the upper crane 5a can not be in a position which is lower than the lower crane 5b. Consequently, the operating range of the upper crane is limited downwards and the range of the lower crane is limited upwards. Secondly, there are interdependencies , as explained above, where the crane 5a depend on the movement operation 11a of the crane 5b. In such circumstances, it is beneficial to always let the plan be the master. In other words, if the first movement operation 5b is delayed, the second movement operation lib only starts when the first

movement operation 11a is fully complete. This requires knowledge of the actual movements of the cranes. Such tracking can either be centrally tracked, using a

controller for a crane set (or even all crane sets, such as the port logistics system 8) , or each crane can track the movements of all other cranes of the same crane set. This helps to prevent deadlocks, which can otherwise occur. Deadlocks are situations where there is a mutual dependency between cranes and can take significant time and effort to solve.

Fig 2b is a schematic diagram illustrating the same movements of Fig 2a, but with two more movements added.

The movements are a third movement 11c by the lower crane 5b of a container from position [2, 2] to position [4, 3] and a fourth movement by the upper crane 5a of the container from position [4, 3] to position [4, 6]. Fig 3 is a schematic graph illustrating time usage of the cranes for the movement operations of Fig 2b. The four movements lla-d make up one overall plan for the crane set comprising the two upper crane 5a and the lower crane 5b. In order not to obscure with unnecessary details, the times for moving a crane into position is disregarded. It can be seen how the upper crane 5a only can start the second movement operation lib at a time 20, once the first movement operation 11a is complete. After the first movement operation 11a is complete, the lower crane 5b can perform the third movement operation 11c which is completed at time 21. The upper crane 5a can perform the fourth movement operation lid only when the second movement operation lib is complete, since the upper crane can only perform one movement operation at any one time. Furthermore, the upper crane 5a can only perform the fourth movement operation lid once the third movement operation 11c is complete, since the fourth movement operation lid operates on the container moved by the third movement operation 11c. The dependencies between cranes are shown with arrows . The fourth movement operation completes at a time 23, which is also the completion time of the overall plan. It can here be seen that any delay to the first movement operation 11a, second movement operation lib and fourth movement operation lid will result in the completion time 23 of the overall plan being delayed. These movement operations are called critical movement operations and are shaded in Fig 3. The third movement operation 11c, however, is not a critical movement operation, and as long as it is completed by time 22, there will be no delay to the completion of the overall plan. According to the embodiments herein, non-critical movement operations , such as the third movement operation 11c are thus deliberately not performed at a maximum speed of the crane in question to conserve energy usage and/or to reduce wear on mechanical components. Non- critical operations can be performed using slower acceleration to use less energy. Non-critical operations can be delayed in start time to balance energy usage across the crane set. Such choices can reduce concurrent power requirements for a crane set, which can e.g. reduce peak power usage of the crane set. Optionally or

additionally, the lifting (also known as pick-up) of a container of a non-critical movement operation can be delayed to a time when another crane in the crane set performs a lowering (also known as set-down) of a container to balance power consumption and power

regeneration. Analogously, the lowering of a container of a non-critical movement operation can be delayed to a time when another crane in the crane set performs a lifting of a container. Also, non critical operations can be performed at a generally lower speed to reduce energy usage and wear of components .

In one embodiment, an operator can set the overall end time 23 to reduce energy requirements and/or to balance power usage.

In other words, a method to perform embodiments of the invention can contain the following steps :

First, it is determined that a delayed completion time of a movement operation of a first crane of the crane set allows the completion time of an overall plan of

movements to remain unaffected.

Secondly, the movement operation is effected with a completion time being later than the originally planned completion time, such that energy consumption and/or power consumption for the crane set is reduced.

Fig 4 shows one example of a computer program product 100 comprising computer readable means. On this computer readable means a computer program 101 can be stored, which computer program can cause a controller to execute the method according to embodiments described herein. In this example, the computer program product is an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) . As explained above, the computer program product could also be embodied as a memory of a device, such as memory 18 of the secure element 10 or memory 23 of the application manager server 20. While the computer program 101 is here schematically shown as a track on the depicted optical disk, the computer program can be stored in any way which is suitable for the computer program product .

Fig 5 is a flow chart illustrating a method according to one embodiment .

In an initial determine overall plan step 20, the overall plan is determined. The overall plan can be for the crane set or for a plurality of crane sets, for a section of the port or even for the whole port . The plan can be determined to minimize its completion time or it can be determined as a compromise between completion time and energy usage and/or power consumption. In one embodiment, an operator is provided with a choice between several options, where each plan has a completion time and energy- usage and/or power consumption for the plan. This allows the operator to select a more energy and/or power

efficient time when time is not critical, a time

efficient plan when time is critical, or a balance between the two as desired. Optionally, time criticality and energy usage and/or power consumption are weighted using weight factors, allowing the overall plan to be determined automatically using the weight factors.

Once the plan is determined, movement operations are effected. For each movement, it is determined in a conditional can movement operation be delayed step 22, if the movement operation can be delayed without affecting the completion time of the overall plan. If this is affirmative, the method continues to an effect movement with reduced energy consumption step 24. Otherwise, the method ends, or in reality continues with the next movement operation. In the effect movement with reduced energy consumption step 24, the movement is effected with reduced energy consumption and/or power consumption, which results in a later completion time than originally planned for the movement operation, as described above. While the embodiments herein mention two cranes in a crane set, any number of suitable cranes can be combined in a crane set.

The plans are described herein as originating from the port logistics system. It is to be noted, however, that the plan can originate from any suitable source, including a planning system from the crane set or even one of the cranes of the crane set.

The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention.

Claims

1. A method for controlling a crane set of at least two automated container cranes, the method comprising the steps of:

determining if a delayed completion time of a movement operation of a first crane of the crane set allows a completion time of an overall plan of movements to remain unaffected; and

effecting, when the determining step provides an affirmative result, the movement operation with a completion time of the movement operation being later than the originally planned completion time of the movement operation, such that energy consumption and/or power consumption for the crane set is reduced.

2. The method according to claim 1, wherein the step of determining comprises determining that, due to an interdependency between plans for the first crane and a second crane, a delayed completion time of the movement operation of the first crane allows the end time of the overall plan of movements to remain unaffected.

3. The method according to any one of the preceding claims, wherein the step of effecting the movement controls acceleration to reduce energy consumption and/or power consumption.

4. The method according to any one of the preceding claims, wherein the step of effecting the movement reduces movement speed to reduce energy consumption and/or power consumption.

5. The method according to any one of the preceding claims, wherein the step of effecting the movement times comprises timing a lifting of the load of the first crane to correspond in time to when the load of another crane of the crane set is lowered.

6. The method according to any one of the preceding claims, wherein the step of effecting the movement times comprises delaying a start time of the movement operation of the first crane.

7. The method according to any one of the preceding claims, wherein the determining step and the effecting step are repeated for each crane in the crane set.

8. The method according to any one of the preceding claims, further comprising the step, prior to the step of determining, of:

determining an overall plan as a compromise between completions time of the overall plan and energy usage and/or power consumption of the overall plan.

9. The method according to claim 8, wherein the step of determining an overall plan comprises using weighting factors for completion time of the overall plan, and power consumption of the overall plan, respectively.

10. The method according to any one of the preceding claims, further comprising the steps of:

presenting at least two options for an overall plan, each option comprising a completion time of the overall plan and an energy usage indication and/or power

consumption indication of the overall plan, and

receiving an input for a selected one of the options .

11. An apparatus for controlling a crane set of at least two automated container cranes, the apparatus comprising: a determiner arranged to determine if a delayed completion time of a movement operation of a first crane of the crane set allows the completion time of an overall plan of movements to remain unaffected; and

a movement controller arranged to, when the

determiner provides an affirmative result, effect the movement operation with a completion time of the movement operation being later than the originally planned

completion time of the movement operation such that energy consumption and/or power consumption for the crane set is reduced.

12. The apparatus according to claim 11, wherein the determiner is arranged to determine that, due to an interdependency between plans for the first crane and a second crane, a delayed completion time of the movement operation of the first crane allows the end time of the overall plan of movements to remain unaffected.

13. The apparatus according to any one of claims 11 to 12, wherein the movement controller is arranged to control acceleration to reduce energy consumption and/or power consumption.

14. The apparatus according to any one of claims 11 to 13, wherein the movement controller is arranged to reduce movement speed to reduce energy consumption and/or power consumption.

15. The apparatus according to any one of claims 11 to 14, wherein the movement controller is arranged to adjust timing of a lifting of the load of the first crane to correspond in time to when the load of another crane of the crane set is lowered.

16. The apparatus according to any one of claims 11 to

15, wherein the movement controller is arranged to delay a start time of the movement operation of the first crane .

17. The apparatus according to any one of claims 11 to

16, further comprising:

an output device arranged to present at least two options for an overall plan, each option comprising a completion time of the overall plan and an energy usage indication and/or power consumption of the overall plan, and

an input device arranged to receive an input for a selected one of the options.

18. A computer program for a crane controller, the computer program comprising computer program code which, when run on the crane controller, causes the crane controller to perform the steps according to a method of any one of claims 1 to 10.

19. A computer program product comprising a computer program according to claim 18 and a computer readable means on which the computer program is stored.