TECHNICAL FIELD

The disclosure relates to call allocation in an elevator system.

BACKGROUND

Elevators are normally allocated based on two allocation methods: continuous allocation or immediate allocation .

In continuous allocation a passenger places a call by pushing an up/down button. With continuous allocation one cannot know for sure how many passengers are actually waiting behind a single call. The number of passengers waiting behind a landing call may be es ^¬ timated, for example, by multiplying the estimated time of arrival to the call with the passenger arrival intensity obtained from historical or forecasted traf ^¬ fic statistics. The result of the multiplication de ^¬ scribes the number of passengers waiting behind the call when an elevator arrives to serve the call. Fur ^¬ ther, in continuous allocation, the allocation decisions can also be changed. For example, if the traffic situation and the estimated time of arrival to a call changes so that the number of passengers behind the call at the moment of serving the call exceeds the available space in the elevator that is currently al ^¬ located to the call, it can be allocated to another elevator .

In immediate allocation, a call is allocated to an elevator immediately after the call is regis ^¬ tered and the serving elevator is signalized for the passenger or passengers who gave the call. This means that the allocation decision cannot be changed even if the traffic situation and the estimated time of arri ^¬ val to the call would have changed so that the esti ^¬ mated number of passengers behind the call exceeds the available space in the elevator. Hence, the estimated time of arrival to the call and the historical passen ^¬ ger arrival intensity give a poor estimate for the number of passengers waiting behind the call. In imme ^¬ diate elevator call allocation, the amount of regis ^¬ tered calls does not often correspond to the actual number of waiting passengers.

Based on the above, there is a need for a so ^¬ lution that would provide more accurate elevator allo ^¬ cation in a situation where there are multiple passengers behind a single call.

SUMMARY

According to a first aspect there is provided a method for allocating an elevator in an elevator system. The method comprises constructing passenger batch size distributions for each pair of floors in a building based on passenger batch journeys, each passenger batch journey defining at least the origin and destination floor of the journey, the number of pas ^¬ sengers relating to the journey and the time of the journey; receiving a call for an elevator; estimating the number of passengers waiting behind the call based on the passenger batch size distributions; and allo ^¬ cating the call to an elevator being able to serve the estimated number of passengers.

According to a second aspect there is provid ^¬ ed a computer program comprising program code, which when executed by at least one processor, performs the method of the first aspect.

According to a third aspect there is provided an elevator control apparatus comprising at least one processor; and at least one memory comprising computer program code for one or more programs, the at least one memory and the computer program code operating together with the at least one processor to cause the apparatus to perform at least the following: construct passenger batch size distributions for each pair of floors in a building based on passenger batch journeys, each passenger batch journey defining at least the origin and destination floor of the journey, the number of passengers relating to the journey and the time of the journey; receive a call for an elevator; estimate the number of passengers waiting behind the call based on the passenger batch size distributions; and allocate the call to an elevator being able to serve the estimated number of passengers.

According to a fourth aspect there is provid ^¬ ed an elevator system comprising a plurality of elevators and an elevator control apparatus according to the third aspect arranged to allocate a call to an el ^¬ evator .

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding and constitute a part of this specification, illustrate embodiments and together with the description help to explain the principles. In the drawings:

Figure 1 is a flow diagram illustrating a method in accordance with one example embodiment.

Figure 2 is a block diagram illustrating an elevator control apparatus in accordance with one ex ^¬ ample embodiment.

Figure 3 is a block diagram illustrating an elevator system in accordance with one example embodi ^¬ ment .

DETAILED DESCRIPTION

Figure 1 is a flow diagram illustrating a method in accordance with one example embodiment.

At 100 constructing passenger batch size distributions for each pair of floors in a building based on passenger batch journeys. Each passenger batch journey defines at least the origin and destination floor of the journey, the number of passengers relat ^¬ ing to the journey and the time of the journey. The construction of the passenger batch size distributions may be performed by recording actual journeys from one floor to another and the number of passengers relating to each journey. In other words, the passenger batch size distributions are based on real passenger data. The passenger batch size distributions thus give de ^¬ tailed information on how and when people use eleva ^¬ tors in a building. For example, normally when an ele ^¬ vator system receives a call, it assumes that there is a single passenger behind the call. The passenger batch size distribution, however, reflects the real amount of passengers. For example, people often go for lunch in a social batch and only one member of the batch gives the destination call. When the journey has been made, the recorded passenger batch distributions take into account the real amount of passengers. One possible solution for constructing passenger batch sizes is diclosed in a granted Finnish patent 121464B.

At 102 a call for an elevator is received. When the elevator system uses immediate allocation, the elevator system knows that a call from a passenger is from a specific origin floor to a certain destina ^¬ tion floor. When the elevator system uses continuous allocation, the elevator system knows that the call from the passenger is from a specific floor and that it is either an up or down direction call.

At 104 the number of passengers waiting be ^¬ hind the call is estimated based on the passenger batch size distributions and at 106 the call is allo ^¬ cated to an elevator being able to serve the estimated number of passengers.

If the call is a destination call, the eleva ^¬ tor system knows the origin floor, the destination floor and the time when the call was received. The el ^¬ evator system uses this information to estimate the number of passengers waiting behind the call. For ex ^¬ ample, the call may have been received at 11:30 on Monday (lunch time) from an office floor to a floor having a restaurant or being an exit floor. The eleva ^¬ tor system checks the passenger batch size distributions and from there it can be learned that the number of passengers behind a call matching these circum ^¬ stances is, for example, four.

The elevator system may, for example, have two alternatives when allocating an elevator to a call. An elevator A has room for two passengers and its waiting time is 25s. An elevator B has room for five passengers and its waiting time is 35s. Since in the estimation it was estimated that there are four passengers behind the call, the elevator B is allocat ^¬ ed although its waiting time is longer than with the elevator A.

If the call is a call in a continuous alloca ^¬ tion elevator system, the elevator system knows the origin floor, the direction of the call (up/down) and the time when the call was received. For example, the call may have been received at 11:30 on Monday (lunch time) from an office floor (origin floor) to a floor having a restaurant or being an exit floor. The eleva ^¬ tor system checks the passenger batch size distributions and from there it can be learned that the number of passengers behind a call matching these circum ^¬ stances is, for example, three. The elevator system may, for example, have two alternatives when allocat ^¬ ing an elevator to a call. An elevator A is arriving at the origin floor but it has room only for two passengers. An elevator B will arrive at the origin floor soon after the elevator A and it has room for four passengers. Since in the estimation it was estimated that there are three passengers behind the call, the elevator B is allocated for the passengers.

In a further example embodiment of Figure 1, it is possible to compute the estimate for the number of passengers waiting behind a call as a type value, an average, a minimum or a maximum of at least one passenger batch size distribution relating to the call. Further, the estimate may also be any other pa ^¬ rameter that can be calculated from the passenger batch size distribution.

In a further example embodiment of Figure 1, from the passenger batch size distributions it is pos ^¬ sible to construct other kind of distributions, for example, by simple summation. For example, the distri ^¬ bution for the passenger batch size from an origin floor to down direction and for a given time interval can be obtained by adding up the distributions for this origin floor and floors below it for this interval. In addition, the distributions can be learned in time and adjusted to possible traffic and population changes in a building by combining the distributions of successive days of a given week day using, for ex ^¬ ample, exponential smoothing.

At least one of the example embodiments pro ^¬ vides an improvement over the earlier solutions since it can be used to estimate the number of passengers waiting behind a call independently of the estimated time of arrival to the call. This is important espe ^¬ cially in immediate call allocation, where allocation decisions cannot be changed even if it would be re ^¬ quired by the changes in the traffic situation.

At least one of the example embodiments also provide an improvement in the allocation decisions made by the elevator control apparatus by estimating the space required by the passengers waiting behind a call. In particular, passenger service is improved, for example, at conference, restaurant and transfer floors where batch sizes vary throughout the day.

Figure 2 discloses a block diagram illustrat ^¬ ing an apparatus 200 according to one example embodi ^¬ ment. The apparatus comprise a processor 202 connected to a memory 204. The apparatus may also comprise sev ^¬ eral processors or memories. The memory 204 or memo ^¬ ries comprises computer program code for one or more programs which, when executed by the processor 202 or processors, the memory and the computer program code operating together with the processor to cause the apparatus 200 to perform at least the following: con ^¬ struct passenger batch size distributions for each pair of floors in a building based on passenger batch journeys, each passenger batch journey defining at least the origin and destination floor of the journey, the number of passengers relating to the journey and the time of the journey; receive a call for an eleva ^¬ tor; estimate the number of passengers waiting behind the call based on the passenger batch size distribu ^¬ tions; and allocate the call to an elevator being able to serve the estimated number of passengers.

Figure 3 illustrates a system according to one example embodiment. The system in Figure 3 is a simplified illustration of an elevator system. The system comprises an elevator control apparatus 300 which is responsible for controlling elevators 302, 304 and 306. The elevator control device 300 is con ^¬ figured to construct passenger batch size distribu ^¬ tions for each pair of floors in a building based on passenger batch journeys, each passenger batch journey defining at least the origin and destination floor of the journey, the number of passengers relating to the journey and the time of the journey; receive a call for an elevator; estimate the number of passengers waiting behind the call based on the passenger batch size distributions; and allocate the call to an eleva- tor being able to serve the estimated number of pas ^¬ sengers .

According to one example embodiment there is provided an apparatus comprising means for construct ^¬ ing passenger batch size distributions for each pair of floors in a building based on passenger batch journeys, each passenger batch journey defining at least the origin and destination floor of the journey, the number of passengers relating to the journey and the time of the journey; means for receiving a call for an elevator; means for estimating the number of passengers waiting behind the call based on the passenger batch size distributions; and means for allocating the call to an elevator being able to serve the estimated number of passengers.

The example embodiments can be included with ^¬ in any suitable device, for example, including any suitable servers, workstations, PCs, laptop computers, capable of performing the processes of the example em ^¬ bodiments, and which can communicate via one or more interface mechanisms. The example embodiments may also store information relating to various processes de ^¬ scribed herein.

Example embodiments may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The exam ^¬ ple embodiments can store information relating to various methods described herein. This information can be stored in one or more memories, such as a hard disk, optical disk, magneto-optical disk, RAM, and the like. One or more databases can store the information used to implement the example embodiments. The databases can be organized using data structures (e.g., records, tables, arrays, fields, graphs, trees, lists, and the like) included in one or more memories or storage de ^¬ vices listed herein. The methods described with re ^¬ spect to the example embodiments can include appropri- ate data structures for storing data collected and/or generated by the methods of the devices and subsystems of the example embodiments in one or more databases.

All or a portion of the example embodiments can be conveniently implemented using one or more gen ^¬ eral purpose processors, microprocessors, digital sig ^¬ nal processors, micro-controllers, and the like, pro ^¬ grammed according to the teachings of the example em ^¬ bodiments, as will be appreciated by those skilled in the computer and/or software art(s). Appropriate soft ^¬ ware can be readily prepared by programmers of ordi ^¬ nary skill based on the teachings of the example em ^¬ bodiments, as will be appreciated by those skilled in the software art. In addition, the example embodiments can be implemented by the preparation of application- specific integrated circuits or by interconnecting an appropriate network of conventional component cir ^¬ cuits, as will be appreciated by those skilled in the electrical art(s) . Thus, the example embodiments are not limited to any specific combination of hardware and/or software.

Stored on any one or on a combination of computer readable media, the example embodiments can in ^¬ clude software for controlling the components of the example embodiments, for driving the components of the example embodiments, for enabling the components of the example embodiments to interact with a human user, and the like. Such software can include, but is not limited to, device drivers, firmware, operating sys ^¬ tems, development tools, applications software, and the like. Such computer readable media further can include the computer program of an example embodiment for performing all or a portion (if processing is distributed) of the processing performed in implementing the example embodiments. Computer code devices of the example embodiments can include any suitable inter- pretable or executable code mechanism, including but not limited to scripts, interpretable programs, dynam ^¬ ic link libraries (DLLs) , Java classes and applets, complete executable programs, and the like. Moreover, parts of the processing of the example embodiments can be distributed for better performance, reliability, cost, and the like.

As stated above, the components of the exam ^¬ ple embodiments can include computer readable medium or memories for holding instructions programmed ac ^¬ cording to the teachings and for holding data struc ^¬ tures, tables, records, and/or other data described herein. In an example embodiment, the application log ^¬ ic, software or an instruction set is maintained on any one of various conventional computer-readable me ^¬ dia. In the context of this document, a "computer- readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable medium may in ^¬ clude a computer-readable storage medium that may be any media or means that can contain or store the in ^¬ structions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer readable medium can include any suitable medium that participates in providing in ^¬ structions to a processor for execution. Such a medium can take many forms, including but not limited to, non-volatile media, volatile media, transmission me ^¬ dia, and the like.

While there have been shown and described and pointed out fundamental novel features as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices and methods de ^¬ scribed may be made by those skilled in the art with ^¬ out departing from the spirit of the disclosure. For example, it is expressly intended that all combina ^¬ tions of those elements and/or method steps which per ^¬ form substantially the same function in substantially the same way to achieve the same results are within the scope of the disclosure. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiments may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. Furthermore, in the claims means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only struc ^¬ tural equivalents, but also equivalent structures.

The applicant hereby discloses in isolation each individual feature described herein and any com ^¬ bination of two or more such features, to the extent that such features or combinations are capable of be ^¬ ing carried out based on the present specification as a whole, in the light of the common general knowledge of a person skilled in the art, irrespective of wheth ^¬ er such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that the disclosed aspects/embodiments may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifica ^¬ tions may be made within the scope of the disclosure.