GB2280760A - An elevator system and a method of controlling such an elevator system - Google Patents

Abstract

In an elevator system having a plurality of elevators 30, 31, 32, the control depends on a control function which defines a relationship among a plurality of control targets. The control targets have corresponding weighting values associated therewith for defining the relative priority among the control targets. In order to permit changes in the control function to be carried out rapidly, in response to changes in the operating conditions of the elevator system, for example time of day or traffic demand, a controller 10 stores a plurality of sets of weighting values, and selects among those sets in dependence on an operating condition. <IMAGE>

Description

AN ELEVATOR SYSTEM AND A METHOD OF CONTROLLING SUCH AN ELEVATOR SYSTEM The present invention relates to an elevator system, in which a controller controls a plurality of elevators moving between floors. The present invention also relates to a method of controlling such an elevator system, and also to a controller for such an elevator system.

As buildings get larger, there is increasing demand for efficient elevator control to ensure satisfactory transportation of people around a building. Modern elevators do not simply to respond to each call (hereinafter, a "hall call") from a floor, but more complex patterns of movement are required. For this reason, controllers are needed to control the elevators.

In an elevator system, there are several factors which affect the behavior of the elevator system. The principle factors are call waiting time (the time between a hall call and the arrival of an elevator car at the corresponding floor), riding time (the time for a passenger picked-up by the elevator at one floor to arrive at the chosen destination), and elevator car congestion (the number of people in an elevator car at any given time). Other such factors will be discussed later. In general, there will be limits to the range of values that these factors can take. Some of these will be set by the elevator system itself. For example, the congestion cannot exceed the maximum loading of the elevator car. However, in general, the limits will be determined by the operator of the elevator system. These limits are referred to herein as control targets.

In determining the control of the elevator system, there is necessarily a trade-off between the factors so that the control targets may not be fully met. For example, in order to reduce the waiting time, the elevator car which is nearest to the floor where the hall call occurs should stop at that floor.

On the other hand, this will then increase the riding time for the people already in that elevator car, and will also increase congestion. On the other hand, if elevators are permitted by the control system to pass floors where there is a hall call, to reduce the riding time for those already in the elevator or because the elevator car is already crowded, then this will increase the waiting time.

Therefore, it is known to define a control function which is dependent on the control targets which affect the elevator system, and also weighting factors associated with each control target, which weighting factors determine the relative importance of the corresponding control target in the control function. Thus, although the operator may have set a minimum waiting time as a control target, the avoidance of congestion may be given a higher priority among the control targets and the relative priorities of the control targets are then determined by the weighting factors.

In JP-A-4-64583, it was suggested that different control functions were established for different types of buildings, so that an elevator for use in a residential building would have a different control function from an elevator system used in an office building or in a department store.

In a further alternative, disclosed in GB-A2240196, it was proposed that weighting factors and the corresponding control function, for a particular building, or for a particular situation within that building, be determined by simulation, and then the elevator system was operated on the basis of the control function thus determined. There was also the suggestion, in GB-A-2240196, that the operator of the elevator system could change the control function.

However, the creation of such simulations took considerable time, and therefore it was not easy for the system to respond to changes in operating conditions.

Therefore, at its most general, the present invention proposes that an elevator system has a controller in which a plurality of sets of weighting factors are predefined, each set comprising the weighting factors for a corresponding control function. Then, the controller selects one of those sets in dependence on a condition of the elevator system.

In this way, the elevator system can respond in an on-line manner to changes in the variable condition. Since the sets of weighting factors are pre-defined, there need be no delay in changing from one set to another, and the system does not require any intervention of the operator to cause such a change. For any control method, control values will be needed as well as the weighting values. However, in general, the control targets do not vary significantly from one method to another since all methods seek to obtain the most satisfactory operation for the operating conditions, and the weighting values thus determine the differences in the methods. The control targets may therefore be fixed, or may be changeable by the operator.

In the simplest case, the variable condition which triggers a change from set of weighting factors to another may be time of day, so that a different control function is used at e.g. morning peaks in traffic from the control function used at e.g. lunch time. However, it is also possible (either in addition or as an alternative) to take into account the traffic demand, i.e. the number of hall calls at any time. Thus, if there are a large number of hall calls, the elevator system may respond to calls in a different way from other times. For example, if there are many hall calls, there is a risk of elevator overcrowding and therefore the corresponding control target may have a greater influence then in the case where there are few hall calls, in which case the dominant control target may be waiting time and/or riding time.

Although the elevator system of the present invention is intended to operate automatically, the operator may influence the method of operation if desired. For example, the operator may change the variable condition which determines the automatic search among the sets of weighting factors, or may change the control targets as mentioned previously.

Although described above in relation to an elevator system, the present invention also relates to a method of controlling such an elevator system.

Furthermore, the present invention relates to a controller for an elevator system.

An embodiment of the present invention will now be described in detail, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a schematic block diagram of an elevator system in which the present invention may be embodied; Fig. 2 is a schematic block diagram of programs and tables which may be used in controlling the elevator system of Fig. 1 according to the present invention; Fig. 3 shows the tables of Fig. 2 in more detail; Fig. 4 is a flow chart of one method of operating the elevator system of Fig. 1 in accordance with the present invention; Fig. 5 is a flow chart of a second method of operating the system of Fig. 1 in accordance with the present invention; Fig. 6 is a third flow chart of a method of operating the elevator system of Fig. 1 according to the present invention; ; Fig. 7 is a flow chart showing the selection of variable conditions in the elevator system of Fig. 1; Figs. 8(a) to 8(d) are tables which may be used in conjunction with the control system of Fig. 1; Fig. 9 shows data tables corresponding to different control methods; and Fig. 10 is a flow chart showing the operation of call assignment in the elevator system of Fig. 1.

In the following description, the sets of weighting factors will be referred to as "parameters".

It will be appreciated that each such "parameter" corresponds to a plurality of weighting factors, that plurality corresponding to the number of control targets which the system is using. The principal control targets relate to the waiting time, the riding time, and the car congestion, but other control targets may be used as will be described in more detail later.

DETAILED DESCRIPTION An embodiment of a group supervisory control system for an elevator system according to the present invention will be described in detail below. Although this embodiment operates on the basis of selection of the control method according to traffic demand, the present invention can be also applied to a case where control method is selected according to the time of day, week etc (time zone).

As shown in Fig. 1, the elevator system of this embodiment has an elevator control system 1, a control method setting unit 2, a group supervisory control system 10, a call/register unit 11 at each floor, a building managing unit 12, a hall indication unit 13, information units 15,16, individual elevator control units 20 to 22, elevators 30 to 32, an operation control program CP10, a traffic demand detection program CP20, a communication program CP30, an operation parameter table CT11, an elevator control data table CT12, a hall call table CT13, and a table for elevator identification CT14.

Thus, the elevator control system 1 comprises a group supervisory control system 10, and individual car control units 20 to 22 controlling each of the elevators 30 to 32. Such a control system may be constructed using known micro-computer control devices.

In operation the group supervisory control system 10 receives signals from a call/register unit 11 at each hall of each floor and/or the signal from a building managing system 12, and outputs signals to hall indication units 13 at the halls for all the elevators. The individual elevator control units 20 to 22 control the movement and the door operation for each car of the elevators 30 to 32, based - on instructions from the group supervisory control system 10. The elevator control units 20 to 22 also control the information units 15 in the cars to provide various information to the people in the cars of the elevators 30 to 32, and the information units 16 for individual elevators at halls (e.g. hall lantern or chime).

The group supervisory control system 10 receives a command from an individualized control method setting unit 2 for each of the basic traffic demands or for particular time zones via a line 6. Thus, the control method setting unit 2 determines the operating condition on the basis of which the selection of the parameters is to occur.

The software for the group supervisory control system 10 is composed of an operation control program CP10, a traffic demand judging program CP20 and .a communication program CP30 as shown in FIG.2.

The operation control program CP10 selects an operating parameter corresponding to the current traffic demand from an operation parameter data table CTll based on the result of the traffic demand judging program CP20. Then the program CP10 executes the group supervisory control, such as assignment process for call from the elevator halls using the selected operating parameter.The operation control program CP10 receives information, for example information about the positions and directions of movement of the elevators transmitted from the individual elevator control units 20 to 22, information from the elevator control data table CT12 such as floor calls from the cars of the elevators, information from the hall call table CT13, information from the elevator specification table CT14 such as number of elevators under group supervisory control.

The traffic demand judging program CP20 determines the current traffic demand in the building from the number of passengers on each floor, the door opening time and so on, and transmits the result to the operation control program Cup10.

The present invention may be changed such that the control method is selected on the basis of time (time zone) by means of changing the traffic demand judging program CP20 described above to a time determination program, as will be described later.

The communication program CP30 controls the communication between the group supervisory control system 10 and the control method setting unit 2 in order to set the required control method corresponding to each of the basic traffic demands. The communication program CP30 may be eliminated if the control method setting unit 2 is integral with the group supervisory control system 10, so that the setting of the control method can be carried out in the group supervisory control system 10.

The software tables used in the group supervisory control system 10, as described above, are the operation parameter table CTll, the elevator control data table CT12, the hall call table CT13, the elevator specification table CT14. These tables are shown in Fig. 3.

This embodiment according to the present invention permits different control functions to be used in a group supervisory control system for elevator by selecting combinations of different parameters from the operation parameter table CT11 described above. It should be noted that, in Fig. 3, the control parameters of operation parameter table CTll refer to only one control target. However, Fig.

3 refers only to the control target which has highest priorities; there will be other control targets which have lower priority in each case. Thus, as previously explained, the control parameter corresponds to a plurality of weighting values for the various control targets, and table CTll thus expresses the dominant weighting value for each control parameter.

The variables K, J and I in the blocks of each table shown in FIG.3 indicate the individual elevator number, the hall call direction, and the hall call floor respectively.

The programs CP10, CP20 and CP30 are divided into a plurality of tasks, and are controlled by a system or operating program (OS), to permit efficient control. Therefore, these programs can be started up from a system timer or from another program.

The operation of an embodiment described above is further illustrated in the flow-chart of Fig. 4, which shows the processing and operation carried out by the operation control program CP10. The processing comprises: (1) starting up the operation control program CP10 on switching on the power source for the system or on re-starting, and executing initial processing such as a clearing process for the elevator control data table CT12 (step DCP10); (2) next, inputting the hall calls from all the floors, re-setting the hall call table CT13, executing re-setting process, outputting a command for on/off of a responding light for the hall calls (step DCP20); ; (3) storing the communication data from the individual elevator control- units 20 to 22 in the elevator control data table CT12 (step DCP30); (4) determining the current traffic demand, and determining the control method for the group supervisory control by selecting the corresponding control operation parameter (step DCP40); (5) executing elevator assignment process for hall call for the elevators using the operation parameter selected in step DCP50 (step DCP60); (6) executing a guidance information process for the elevator services such as the basis of the current control method, the information on landing, and the guidance information from the building managing system 12 (step DCP70);; (7) finally, executing other processes which are not directly related to the present invention but need for the elevator control (step DCP80).

The processes from step DCP20 to step DCP80 described above are repeatedly executed to perform the group supervisory control system until the system is turned off or a program abnormality occurs.

Although the processing and operation of the operation control program CP10 of the embodiment described selects the control method on the basis of traffic demand, the present invention may be applied to the control method being selected by time (time zone). Fig. 5 is a flow-chart showing the processing and operation of the operation control program CP10 in such a case. Since the operation parameters are selected corresponding to the time zone in this case, it is sufficient that the traffic demand determination of step DCP40 in Fig. 4 is changed to the time zone determination of step DCP41 as shown in Fig. 5. Apart from this difference, the flow-chart of Fig. 5 is identical to that of Fig. 4.

Further, in the present invention, the control method may be selected by taking both the time (time zone) and the traffic demand into consideration. In this case, the processing and operation of the operation control program CP10 is shown in the flowchart in Fig. 6.

The processing is such that the targets are selected for each time zone, the control method is selected on the basis of the targets thus selected and the current traffic demand. The processing shown in Fig 6 is generally similar to that of Fig 4 or Fig 5.

However, the traffic demand is determined in step DCP40, then the target is selected according to the determination of time zone and the result of the determination in the additional process of step DCP42, the control method being selected using the traffic demand and the target in step DCP50.

The selecting process for the control method in step DCP50 in Figs. 4 to 6 described above will be described below, referring to the flow-chart shown in Fig. 7. In Fig 7, three types of selecting methods for the control method are-illustrated. The methods are traffic demand grouping, time zone grouping, and combination of targets grouped by time zone and traffic demand. The flow-chart shown in Fig. 7 is constructed so as to be capable of coping with these three cases.The processing comprises: (1) on starting the processing, determining whether or not the time zone is set, determining the control method using only the traffic demand determined at step DCP40 described above if the time zone is not set (step DCP5O1, DCP505); (2) determining whether or not the targets are set if the time zone is set in step DCP5O1, determining the control method using only the time zone identified in step DCP41 described above if targets are not set (step DCP502, DCP504); (3) determining the control method using the combination of the traffic demand determined in step DCP40 and the target selected in step DCP42 if the target is set (step DCP503);; (4) determining the operation parameters corresponding to the control method determined in step DCP503, DCP504 and DCP505 (step DCP506).

The construction of the data table used in the process to select the control method in step DCP503, DCP504 and DCP505 described above will be described below, referring to Figs. 8(a) to 8(d). The tables shown in Figs. 8(a) to 8(d) may be stored in the operation control program CP10 or connected to the operation control program as separate tables.

Fig. 8 (a) is an example of a data table used in selecting the control method according to the traffic demand, and is a table in which pairs of traffic demand numbers and the control method numbers corresponding to the traffic demand numbers are stored. Although traffic demand is variable, for ease of operation it is desirable to divide the traffic demand that can occur into traffic demand ranges, each of which has a corresponding demand number. Then, when the current traffic demand is determined, =the traffic demand range in which the particular demand lies is determined, permitting the control method number corresponding to the traffic demand number to be obtained by reference to the table of Fig. 8(a).

This enables the control method to be selected.

Fig. 8(b) is an example of a data table used in selecting the control method according to the time zone group, and is a table in which pairs of the time zone numbers and the individualized control method numbers corresponding to the time zone numbers are stored. When the time zone is determined, the control method number corresponding to the time zone number can be obtained by reference to the table. Thus, again, the control method can be selected.

Fig. 8(c) and Fig. 8(d) are examples of data tables used in selecting the control method according to the combination of the target grouped by time zone and traffic demand. Fig. 8(c) is a table in which pairs of time zone numbers and target numbers corresponding to the time zone numbers are stored.

Fig. 8(d) is a two-dimensional table in which the control method numbers are stored corresponding to the combination of the target numbers and the traffic demand numbers.

When the control method is selected using these tables, an target number set according to the time zone is selected first, based on the time zone, using Fig. 8(c). Next, using the two-dimensional table of Fig. 8(d), the control method is selected on the basis of the target selected using Fig. 8(c) and the traffic demand. For example, when the target number is 4 and the traffic demand number is 3, method number (4) is selected as the control method.

There are some cases where it is impossible, or impractical, to select an appropriate control method.

For example, if there are no hall calls at all for a considerable length of time, and the system is operating solely on the basis of traffic demand, then there is no information to enable the control method to be selected. Also, there are some situations where the control method is irrelevant. For examples, when a building first opens, the only elevator movement which is important is from the entrance. Therefore, for such cases, the elevator system may default to one particular control method which it uses until there is sufficient information available to enable a more optimum control method to be used. This is shown in Fig. 8(d) in which traffic demand number 1 causes control method number (1) to be carried out independent of the target number.

The traffic numbers 1 to 8 indicate, for example, a default operation, traffic demand at office-going time, traffic demand at office-leaving time, traffic demand at first half of lunch time, traffic demand at latter half of lunch time, traffic demand at slack time, traffic demand at normal time and so on. The time zone numbers 2 to 8 thus indicate, for example, office-going time zone, office-leaving time zone, first half of lunch time zone, latter half of lunch time zone, slack time zone, normal time zone and so on.

As has previously been mentioned, there are many possible control targets which can be used in the present invention. The principal ones are the waiting time, the riding time, and the degree of car congestion. However, other control targets may also be used. For example, it may be desirable for security purposes to minimize or eliminate mixing of people from one floor with another floor, minimizing the number of people who will occupy a car over a particular cycle of the car (each is related to both car congestion and riding time). Also, the number of times which a car will pass a floor where there is a hall call (pass-by rate), the instantaneous, or rate of change, of the assignment of hall calls to elevator cars (registration rate), the amount of power consumed by the elevator system, etc may be used as to form control targets.Each of these factors may have a predetermined value (i.e. they become control targets). Indeed, such setting of the control targets may be achieved by the method described in GB-A2240196.

Then, many different control methods can be set by varying the weighting values which are assigned to the control targets. In the simplest case, each of the control targets discussed above may be given priority, but many other control methods are possible by adjusting the weighting values. With the present invention, however, sets of weighting values (parameters) are predetermined and stored by the elevator control system. Whilst simulation models such as those disclosed in GB-A-2240196 may be used to generate the weighting values, the full range of such weighting values which are permitted by the system should be determined prior to the operation of the system, so that the system can select among the sets of weighting values (parameters) in a real-time (online) manner.

Fig. 9 shows an example of a data table storing the operation parameters corresponding to the control method numbers. Such tables corresponding to the control methods, the number of which is equal to the number of the control methods, are prepared in advance, and are constructed as a whole in the format of a table CT11 shown in Fig. 3. The content of the table are plural kinds of the operation parameters and the associated control targets and weighting values.

Therefore, when a control method number is determined in steps DCP503, DCP504 or DCP505, a data table having the corresponding number is selected from the plurality of data tables shown in Fig. 9 and operation parameter required by the operation control program CP1O shown in Fig. 2 are selected from the selected table.

The assignment process for call from elevator hall in step DCP60 in Fig. 4 to Fig. 6 described above will be described below, referring to the flow-chart shown in Fig. 10. The processing comprises: (1) setting the initial values of the loop variables for direction and floor (direction Jn, floor In) in order to execute the assignment process for calls from elevator hall regarding upward/downward movement and all floors (step HCSP10); (2) determining whether or not there is any assignment request for a call from an elevator hall in the loop (step HCSP20). This may involve determining whether or not there is any newly produced call from an elevator hall or simply whether or not there is any registered call;; (3) executing an assigned elevator selection process for the call from the elevator hall if there is any assigned request for call determined in step HCSP20 (step HCSP30); (4) determining whether or not the process for all floors is completed after completion of step HCSP20 or if there is no assigned request for a call in step HCSP20; if completed, the processing is completed; if not, the loop variables (Jn, In) are updated and the processing returns to step HCSP20.

The determination in step HCSP20 and the assignment process of HCSP30 are repeated until the process for all floors is completed (steps HCSP40 and HCSP50).

In the embodiments described above, the control method is selected automatically on the basis of traffic demand and/or time zone. However, the operator of the elevator system may select between these alternatives, and indeed the operator may select which of the control targets are to be used.

Thus, with the present invention, the control method by which the elevators of the elevator system are controlled may be varied in dependence on changes in the variable condition such as time or traffic demand. Since the weighting values for the control targets are predetermined, and the system selects a set of weighting values from a plurality of such sets, the system may respond rapidly and efficiently to changes in operating conditions. Thus, the flexibility of the system is increased, and improved elevator service is permitted.

According to the present invention, an optimized individualized control method for elevator suitable for the use of building can be selected depending on the traffic demand or the time zone in the building, and then a flexible and fine service can be realized.

Claims (14)

1. An elevator system having a plurality of elevators serving a plurality of floors, and a controller for controlling movement of the elevators, the controller being arranged to operate, at any given time, in dependence on a selected control function, which control function is dependent on a plurality of control targets and a corresponding plurality of weighting factors for said control targets, wherein the controller has means for storing a plurality of sets of said weighting factors, each set comprising the weighting factors for a corresponding control function, means for determining at least one variable condition of the elevator system, and means for selecting among said sets of weighting factors, thereby to provide variation of the selection of the control function for the elevators.

2. A system according to claim 1, wherein the at least one variable condition is time of day.

3. A system according to claim 1 or claim 2, wherein the at least one variable condition is traffic demand.

4. A system according to any one of the preceding claims, wherein the controller has operatorcontrollable means for selecting said at least one variable condition.

5. A system according to any one of the preceding claims, wherein said control targets include predetermined values of at least some of: call waiting time, riding time, elevator car congestion, passenger mixing rate, reservation rate, reservation change rate, pass-by rate, and power consumption.

6. A system according to claim 1, having operatorcontrollable means for selecting said predetermined values of said control targets.

7. A method of controlling an elevator system having a plurality of elevators serving a plurality of floors in which the control at any given time is based on a selected control function dependent on a plurality of control targets and a corresponding plurality of weighting factors for said control targets; wherein a plurality of sets of said weighting factors are predefined, each set comprising the weighting factors for a corresponding control function, and there is selection among the sets of weighting factors in dependence on at least one variable condition of the elevator system, thereby to provide variation of the selection of the control function for the elevators.

8. A method according to claim 7, wherein the at least one variable condition is time of day.

9. A method according to claim 6 or claim 7, wherein the at least one variable condition is traffic demand.

10. A method according to any one of claims 7 to 9, wherein the at least one variable condition is selectable by an operator of the elevator system.

11. A method according to any one of claims 7 to 10, wherein said control targets include predetermined values of at least some of: call waiting time, riding time, elevator car congestion, passenger mixing rate, reservation rate, reservation change rate, pass-by rate, and power consumption.

12. A controller for controlling movement of elevators of an elevator system, the controller being arranged to operate, at any given time, in dependence on a selected control function, which control function is dependent on a plurality of control targets and a corresponding plurality of weighting factors for said control targets, wherein the controller has means for storing a plurality of sets of said weighting factors, each set comprising the weighting factors for a corresponding control function, means for determining at least one variable condition of the elevator system, and means for selecting among said sets of weighting factors, thereby to provide variation of the selection of the control function for the elevators.

13. An elevator system substantially as herein described with reference to and as illustrated in the accompanying drawings.

14. A method of controlling an elevator system substantially as any one herein described with reference to the accompanying drawings.