Elevator group management system and elevator assignment method

Abstract: An elevator group management system for managing a plurality of elevators is disclosed wherein the system comprises a plurality of control devices for executing overall assignment processes of the elevators in response to hall calls which take place on particular floors and a plurality of sub tasks, distributedly disposed in the control devices. for calculating times for which the elevators respond to the hall calls. When the control devices receive hall calls at the same time or nearly at the same time, they in parallel activate sub tasks distributedly disposed in the control devices and determine most suitable elevators in response to the hall calls.

Description: The present invention relates to an elevator group management system and elevator assignment method for assigning a most suitable elevator from a plurality of elevators which respond to an elevator call which takes place on a particular floor (hereinafter named a "hall call"). Recently, a most suitable elevator is rationally and quickly assigned from a plurality of elevators which respond to a hall call which takes place on a particular floor by means of a small computer such as a microcomputer or the like. In addition, recently, the assignments of such elevators are controlled by using a plurality of group management control devices. An advantage of this method is that a task group for calculating a time for which each elevator responds to a hall call is distributed to a plurality of group management control devices and thereby a large number of processes can be shared by them. The task group is activated with a control command by a main task with which one of the group management control devices is provided. The main task is a task for controlling the overall assignments of the elevator group. The main task executes a process for determining an elevator which should respond to the hall call in accordance with information collected from the task group. Nevertheless, in such an elevator group management system, as the scale of the elevator system becomes large, that is, the number of hall calls due to increase of floors and elevators becomes large, the group management control device having main task is concentratedly loaded. Thus, when a plurality of hall calls take place nearly at the same time, the later hall calls are processed with a long time delay. It is known from our GB-A-2 217 046 to parallelise the computation to determine the optimum elevator for a particular single hall call, but this still requires hall calls to be dealt with serially. An object of the present invention is to provide an elevator group management system and elevator assignment method for assigning in parallel, where elevators respond to a plurality of hall calls which take place at the same time or nearly at the same time so as to improve the efficiency of the overall processes in the system. To accomplish such an object, the elevator group management system for managing a plurality of elevators according to the present invention is defined in Claim 1. In addition, the elevator assignment method according to the present invention is that defined in Claim 3. Thus, according to the present invention, elevators can be assigned in parallel in response to a plurality of hall calls which take place at the same time or nearly at the same time and thereby the efficiency of the overall processes in the system can be improved. Fig. 1 is a block diagram showing the overall construction of an elevator group management system of an embodiment according to the present invention; Fig. 2 is a block diagram describing the overall construction of software in the elevator group management system shown in Fig. 1; Fig. 3 is a block diagram showing an example of allocation of each task in each group management control device; Fig. 4 is a flow chart showing a process flow-of assignments of elevators; Fig. 5 is a schematic showing timings of parallel assignment processes of elevators in response to two hall calls; Fig. 6 is a block diagram showing a sub task transfer process executed between the group management control devices; and Fig. 7 is a flow chart showing a process for transferring a sub task. Now, with reference to the accompanying drawings, an embodiment of the present invention will be described. Fig. 1 is a block diagram describing the overall construction of an elevator group management system of an embodiment according to the present invention. In the figure, the reference numerals 1-1 and 1-2 are group management control devices for managing an elevator group. The reference numerals 2-1 to 2-N are a plurality of discrete control devices for individually controlling an elevator. The group management control devices 1-1 and 1-2 and the discrete control devices 2-1 to 2-N are composed of small computers which use a single or a plurality of microcomputers. The group management control devices 1-1 and 1-2 and the discrete control devices 2-1 to 2-N are mutually connected through a high speed transmission line 3 and a low speed transmission line 4. The high speed transmission line 3 is used to exchange information necessary for managing the elevator group among the group management control devices 1-1 and 1-2 and the discrete control devices 2-1 to 2-N. The low speed transmission line 4 is used to transfer information among the group management control devices 1-1 and 1-2, the discrete control devices 2-1 to 2-N, a hall call button 5 on each floor, a monitor panel 6 in a monitor room, and so forth. Each hall call button 5 is connected to the low speed transmission line 4 through a transmission control device 7. Fig. 2 is a block diagram showing the overall construction of software with which the elevator group management system is provided. As shown in the figure, a real time OS 8, which is an operating system, controls the activation and stop of a discrete control function task 9, a group management control main function task (hereinafter named the main task) 10, a group management control sub function task (hereinafter named a sub task) 11, and a transmission control task 12. The discrete control function task 9 is used to control the discrete control devices 2-1 to 2-N. The sub task 11 executes a process for calculating a time for which each elevator responds to a hall call, that is, an evaluation value with respect to a time necessary for moving the elevator to the floor on which the hall call takes place in accordance with a particular evaluation equation. The number of sub tasks 11 is the same as that of elevators. The main task 10 is used to execute an overall assignment process of the elevator group. In other words, when a hall call takes place, the main task 10 activates all the sub tasks 11 and executes the process for determining a most suitable elevator in response to the hall call in accordance with an evaluation value obtained by each sub task 11. The transmission control task 12 is a task for controlling information transmitted between the group management control devices 1-1 and 1-2. Fig. 3 is a schematic showing an example of allocation of each task in the group management control devices 1-1 and 1-2. As shown in the figure, the one group management control device 1-1 is provided with the main task 10-1, the four sub tasks 11-1 to 11-4, and the transmission control task 12. On the other hand, the other group management control device 1-2 is provided with the main task 10-2, the four sub tasks 11-5 to 11-8, and the transmission control task 12. In other words, the sub tasks 11-1 to 11-8 are distributed to the group management control devices 1-1 and 1-2. Then, with reference to Fig. 4, the operation of the elevator group management system will be described. When a hall call takes place, the group management control device 1-1 or 1-2 which is not executing the main task 10 receives the hall call and activates the main task 10 (in the step 401). When both the group management control devices 1-1 and 1-2 are not executing the main task 10, the predetermined group management control device 1-1 receives the hall call. The main task 10-1 sends an activation command to the discrete control devices 2-1 to 2-N and activates all the sub tasks in the group management control devices 1-1 and 1-2 (in the step 402). Each of the sub tasks 11-1 to 11-8 receives information from the discrete control function task 9 of each of the discrete control devices 2-1 to 2-N and thereby knowing the present position of the elevator. Thereafter, each of the sub tasks 11-1 to 11-8 calculates an evaluation value with respect to a time for which the elevator responds to the hall call. Each of the sub tasks 11-1 to 11-8 sends the calculated evaluation value to the main task 10-1 of the group management control device 1-1. When the main task 1-1 receives all the evaluation values from all the sub tasks 11-1 to 11-8 (in the step 403), it checks whether or not there are evaluation values which should be recalculated (in the step 404). In other words, the main task 10-1 monitors elevators which are assigned in response to other hall calls while collecting all the evaluation values. If such elevators are present, the main task 10-1 treats the evaluation values which have been received as those to be recalculated. When the main task 10-1 detects that there are evaluation values to be recalculated, it cancels the evaluation values and then requests the sub tasks 11 which calculated them to recalculate evaluation values (in the step 405). After the main task 10-1 has received all correct evaluation values from all the sub tasks 11-1 to 11-8, it compares all the evaluation values, determines a most suitable elevator in response to the hall call (in the step 406), and issues a movement command to the discrete control device 2-1 to 2-N which controls the elevator (in the step 407). While the main task 10-1 of the group management control device 1-1 is assigning an elevator, if another hall call takes place, the main task 10-2 of the other group management control device 1-2 is activated. Likewise, the main task 10-2 assigns an elevator by using the sub tasks 11-1 to 11-8 which have been used by the main task 10-1. Fig. 5 is a schematic showing timings of a process for assigning elevators in response to two hall calls Alpha and Beta which take place with a small time delay. As was described above, in this elevator group management system, the process for assigning elevators in response to two hall calls Alpha and Beta which take place nearly at the same time can be executed in parallel without a time delay and thereby the elevators can be effectively assigned. In this elevator group management system, the following process is also executed. For example, it is assumed that the number of available elevators is limited depending on the time zone. When the group of the sub tasks 11 according to available elevators is concentrated on the one group management control device, the load is concentrated thereon. In this case, as shown in Fig. 6, part of the sub tasks 11-3 and 11-4 allocated in the the group management control device 1-1 on which the load is concentrated are automatically transferred to the other group management control device 1-2. Then, with reference to Fig. 7, this sub task transfer process will be described. Each of the group management control devices 1-1 and 1-2 stores the total number of assignments of the elevators according to the sub tasks 11 controlled thereby and the number of assignments of each elevator. The one group management control device 1-1 which completed the elevator assignment process of an elevator in response to a hall call asks the other group management control device 1-2 for the total number of assignments of elevators by itself up to that time (A) (in the step 701). Thereafter, the group management group control device 1-1 compares the total number of assignments of elevators by itself (B) with the total number of assignments by the other group management control device 1-2 (A) (in the step 702). When the group management control device 1-1 determines that the absolute value of the difference between the two values (¦ A - B ¦) exceeds a predetermined value (in the step 703) and that the total number of assignments by itself (B) is greater than the total number of assignments by the other group management control device 1-2 (A) (in the step 704), it transfers the sub task 11 with the smallest number of assignments in the group of those thereof to the other group management control device 1-2 (in the step 705). When the group management control device 1-1 determines that the absolute value of the difference of the two values (¦ A - B ¦) exceeds the predetermined value (in the step 703) and that the total number of assignments by itself (B) is smaller than the total number of assignments by the other group management control device 1-2 (A) (in the step 704), it asks the other group management control device 1-2 to transfer the sub task 11 with the smallest number of assignments in those thereof (in the step 706). This process is repeatedly executed whenever each of the group management control devices 1-1 and 1-2 completes the elevator assignment process. As was described above, according to the elevator group management system according to the present invention, the elevator assignment processes in response to two hall calls which take place at the same time or nearly at the same time can be executed in parallel without a time delay and thereby the assignment processes of the elevator group can be effectively executed. In the elevator group management system, when the number of available elevators is limited, the load concentration on the group management control devices 1-1 and 1-2 can be prevented.

Claims: An elevator group management system for managing a plurality of elevators, comprising: a plurality of control means (1-1, 1-2) for executing overall assignments of said elevators in response to hall calls which take place on particular floors; means for initiating a plurality of calculation tasks (10, 11), the tasks being distributed between said plurality of control means, for calculating the time required for respective ones of said plurality of elevators to respond to each hall call; wherein a first (1-1) of said plurality of control means responds to a first hall call and activates a first set of calculation tasks allocated to said first control means (1-1) for individually calculating the times that would be required for the respective elevators to respond to the first hall call, thereby determining the most suitable of the elevators to respond to said first hall call; and dispatching means (2-1, 2-2, ...2-N) for dispatching the most suitable elevators to respond to hall calls; characterised in that a second (1-2) of said plurality of control means responds to a second hall call, only when the second hall call is received subsequent to the first hall call and while the first (1-1) of said plurality of control means is responding to said first hall call, and activates a second set (10-2) of calculation tasks allocated to said second control means for individually calculating in parallel the times that would be required for the respective elevators to respond to a second, copending hall call, thereby determining the most suitable of the elevators to respond to said second hall call; and in that the dispatching means (2-1, 2-2, ...2-N) responds to the results of the first and second sets of calculation tasks (10-1, 10-2) respectively to dispatch the most suitable elevators to respond to the first and second hall calls respectively. An elevator group management system according to Claim 1, wherein said first and second sets of calculation tasks (10-1, 10-2) each calculate times that would be required for said plurality of elevators to respond to a respective hall call by causing a plurality of subfunctions (11) to be executed; and comprising means for determining, as a measure of load, the total number (A, B) of assignments which have been executed by each respective one of said first and second control means; and transfer means for transferring some (11-3, 11-4) of said subfunctions (11) from one of the control means (1-1) with a larger load (A) to another of the control means (1-2) with a smaller load (B) when the difference (A-B) between said loads exceeds a predetermined value. A method for managing a plurality of elevators in an elevator group management system in response to a plurality of hall calls, comprising the steps of: receiving, at each of a plurality of control means (1-1, 1-2), the plurality of hall calls; calculating, in a plurality (10, 11) of calculation tasks distributed between said control means, anticipated response times required for said plurality of elevators to respond to each hall call; determining, in said plurality of control means, the most suitable elevators to respond to said hall calls based on said calculated response times; wherein a first (1-1) of said plurality of control means responds to a first hall call and activates a first (10-1) set of calculation tasks allocated to said first control means (1-1) for individually calculating the times that would be required for the respective elevators to respond to the first hall call, thereby determining the most suitable of the elevators to respond to said first hall call; and dispatching the most suitable elevators to respond to the respective hall calls in accordance with the determination by the calculation means; characterised in that a second (1-2) of said plurality of control means responds to a second hall call, only when the second hall call is received subsequent to the first hall call and while the first (1-1) of said plurality of control means is responding to said first hall call, and activates a second (10-2) set of calculation tasks allocated to said second control means (1-2) for individually calculating in parallel the times that would be required for the respective elevators to respond to a second, copending hall call, thereby determining the most suitable of the elevators to respond to said second hall call; and by dispatching the most suitable elevators to respond to the first and second hall calls respectively in accordance with the determinations by the first and second control means. A method according to claim 3 for managing a plurality of elevators in an elevator group management system in response to a plurality of hall calls, wherein said first and second sets of calculation tasks (10-1, 10-2) each calculate times that would be required for said plurality of elevators to respond to a respective hall call by causing a plurality of subfunctions (11) to be executed; and including the steps of determining, as a measure of load, the total number (A, B) of assignments which have been executed by each respective one of said first and second control means (1-1, 1-2); and transferring some (11-3, 11-4) of said subfunctions (11) from one (1-1) of said control means with a larger load (A) to another (1-2) of said control means (B) with a smaller load when the difference (A-B) between said loads exceeds a predetermined value.

Inventors: KUBO SUSUMU C O INTELLECTUAL P, OKATAKU YASUKUNI C O INTELLECT, KUBO, SUSUMU, C/O INTELLECTUAL PTY. DIVISION, OKATAKU, YASUKUNI, C/O INTELLECTUAL PTY. DIVISION
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1991
Main classification: B66B1
IPC codes: B66B1