Apparatus for performing group control on elevators utilizing distributed control, and method of controlling the same

An apparatus for performing group control on elevators, wherein a plurality of elevators are operated for a plurality of floors, a predetermined evaluation calculation is performed for each of the plurality of elevators upon generation of a hall call, an optimum elevator car is selected on the basis of an evaluation calculation result, and the selected elevator car is assigned to the hall call, thereby responding to the hall call, the apparatus, comprises a unit controller, arranged in units of cars of the elevators, for controlling unit control of each car and inputting/outputting information associated with its own car, a plurality of group controllers for performing the evaluation calculation for determining hall-call assignment in units of cars on the basis of the information associated with its own car and for performing group management of each elevator car on the basis of an evaluation calculation result, and a communicating circuit for causing the plurality of group controllers to communicate with each other through a first data field and causes the unit control means and the group controllers to communicate with each other through a second data field independent of the first data field.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an apparatus for performing group control 
on a plurality of elevators which are operated for a plurality of floors 
and, more particularly, an improvement of a group management elevator 
system having a distributed control function. 
2. Description of the Related Art 
In recent years, in order to improve operation efficiency of a plurality of 
elevators installed parallel to each other and to offer better elevator 
services to passengers, the elevators are systematically controlled by a 
small computer such as a microcomputer to be quickly assigned to hall 
calls at respective floors. That is, when a hall call is made, an elevator 
car which allows optimum service is controlled to be selected and assigned 
to the hall call, and other elevator cars are controlled not to respond to 
this hall call. 
In group control of this system, some advanced group control systems have a 
learning function. Interfloor traffic and average arrival time intervals 
between the halls can be managed in real time on the basis of measurements 
of cage-call registration data and passenger load data upon response to 
each hall call, as disclosed in, e.g., U.S. Pat. No. 4,760,896, "Apparatus 
for Performing Group Control on Elevators", patented to Yamaguchi on Aug. 
2, 1988. The measurement data are processed by a computer in units of time 
zones to detect an elevator utilization demand of each building. Group 
control such as determination of an optimum car in response to a hall 
call, setting of a busy morning (opening) time zone, a lunchtime zone, and 
a busy evening (closing) time zone, setting of dispersed waiting zones of 
the elevator cars in non-busy hours, and setting of the number of halt 
elevator cars for energy saving. 
A group control apparatus generally manages distributed control by a 
plurality of small computers. An elevator car unit control apparatus as a 
slave connected to the group control apparatus as a master is constituted 
by a small computer such as a microcomputer in a digital arrangement. 
High-speed information transmission is performed between the computer in 
the group control apparatus and the computer in the elevator car unit 
control apparatus via a serial transmission line or the like. 
In the elevator system for performing group control, a ratio of control 
software utilized by the microcomputers to control hardware is high. 
Therefore, the overall system is complicated and digitized to perform 
high-speed information transmission between the computers. 
Under these circumstances, a conventional group control apparatus is a 
centralized control system. In this centralized control system, the group 
control apparatus exchanges basic data with respective elevator car unit 
control apparatuses, and performs data processing in units of cars on the 
basis of the basic data. 
When the scale of the group control elevator system is increased, i.e., 
when the numbers of floors and cars are increased, the computers in the 
group control apparatuses are overloaded. In this case, when the demand 
for hall calls is increased, the computer processing is affected by its 
capacity. For example, in a system having a reservation display function, 
the computer of the group control apparatus has a large load. A processing 
period running from the generation of a hall call to the time of an 
indicator-ON of an optimum car varies depending on the numbers of floors 
and elevator cars. The load on the computers in the total system is 
unbalanced. In addition, when a system-down occurs, the group control 
function fails at once. As a result, computer processing efficiency for 
the total system is poor. 
Under the above circumstances, distributed control of control functions of 
an elevator system using multiple stations has been developed to aim at 
averaging of the load balance of control computers. 
A system configuration of distributed control of the control functions is 
shown in FIG. 15A to 15C. 
FIG. 15A shows a hierarchical system in which a group management slave 
controller for performing processing of each car unit is combined in a 
one-to-one correspondence with a unit controller for controlling a control 
function of the unit elevator. Each group management slave controller is 
connected in a slavemaster relationship to a group management master 
controller which is independently arranged to control the total system. 
FIG. 15B shows a hierarchical system in which the function of the group 
management master controller of FIG. 15A is assigned to one of group 
management slave controllers for performing processing of elevator car 
units. 
FIG. 15C shows a system in which the function of each unit controller and 
the function of the corresponding group controller are performed by one 
control computer. 
In either system described above, processing of each elevator car unit has 
a one-to-one correspondence with the control computer. Load distribution 
is performed on the basis of the master control mechanism management. 
Therefore, the group management master function can be shifted between the 
slave controllers or systems. 
However, the slave control function is not shifted. If a given slave 
controller fails, it is difficult to allow the remaining control computers 
to provide a cooperation function, i.e., an autonomous compensation 
function. For this reason, when a group management slave controller 
corresponding to a given unit controller fails, group control for the 
respective elevator is maintained except for the elevator car belonging to 
the failed group management slave controller. However, the failed elevator 
car is kept inactive or out of group control, thus degrading utilization 
efficiency. 
In the systems shown in FIGS. 15A and 15B, in order to control n 
controllers, n (FIG. 15B) or (n+1) (FIG. 15A) computers are required. The 
control load is changed due to the number of floors of a building and/or 
the grades of the control systems, and fixed n or (n+1) distributed 
control systems are required. Cost performance is degraded against the 
purpose of load distribution. As a result, the flexibility and versatility 
of the system become poor. 
In the system shown in FIG. 15C, all controllers are commonly arranged in 
the same computers as the unit controllers which must maintain absolute 
reliability as compared with the group control system. For this reason, a 
function of the unit controller having a higher priority is degraded by an 
influence of the group control system generally having a large control 
load. In addition, an elevator car unit corresponding to a control 
computer which failed due to a failure of the group control system also 
fails. 
In the system of FIG. 15C, once a unit control system fails, the failure 
results in a decisive failure of the system. In addition, a unit control 
system fails upon a failure of the group control systems having an 
entirely different function from that of the unit control system, thus 
posing significant problems on reliability and safety. The group control 
system has limitations that its processing must be performed during 
interruption of processing of the unit control system having the higher 
priority. Therefore, the system in FIG. 15C has application limitations by 
the number of floors and/or the grades of the control systems. 
In all the systems of FIGS. 15A, 15B and 15C, n computers (FIG. 15B) or 
(n+1) computers (FIG. 15A) are required, or no computer is required but 
the unit control function and the computer function are commonly provided 
(FIG. 15C). Although the distributed control systems are arranged to aim 
at load distribution, versatility of load distribution efficiency is 
limited by the number of floors and/or the grades of the control systems. 
That is, the above conventional systems are not satisfactory from the 
viewpoint of creation of a distributed control system having autonomous 
controllability/compensatability. 
In a system for performing group control on elevators, control computers 
are used for group control and unit control. In order to average the loads 
of the respective control computers and perform highly efficient control, 
distributed control is proposed to distribute functions necessary for 
group control to a plurality of computers. Distributed control is 
advanced, and a one-to-one correspondence between elevator car unit 
processing and unit control is established. Therefore, the load can be 
distributed by the master control mechanism management base. Each unit 
control apparatus for controlling various operations of the elevator unit 
and each distributed control apparatus for performing distributed control 
for group control are separately provided in accordance with the 
processing capacity and unit control reliability which is of prime 
importance. These apparatuses are arranged in units of elevator car units. 
In order to control n elevators in the group, the load is changed by the 
number of floors and/or grades of the control systems. However, n 
distributed control systems are required to result in a wasteful system. 
When one of the group control systems fails, the unit control system 
corresponding to the failed group control system cannot exchange data for 
group control. Therefore, this unit control system for the failed elevator 
car is considered out of control and removed from group control. Although 
group control of the total system is normally performed, overall 
utilization efficiency is degraded. 
In a system wherein the unit control function and the group control 
function are assigned to each unit control computer in order to reduce the 
cost, when the group control system fails, the unit control system fails 
accordingly. Therefore, reliability of unit control is degraded. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an apparatus for 
performing group control on elevators and a method thereof, wherein a 
group control function is executed while compensation between control 
computers is established, reliability of unit control is maintained, 
system efficiency can be improved, and the system can be substantially 
free from an influence of a system load. 
In order to achieve the above object of the present invention, the present 
invention is constituted as follows. A plurality of elevators are operated 
for a plurality of floors. Each elevator is evaluated by a predetermined 
calculation in response to a hall call. An optimum elevator is selected 
and the selected elevator is assigned to the hall call in accordance with 
the evaluation result. An apparatus for performing group control on 
elevators comprises the following means: (a) unit control means, arranged 
in units of elevator cars, for controlling unit control of each elevator 
car and inputting/outputting information associated with its own car; (b) 
a plurality of group control means each having a first process for 
exchanging each car information, a second process for determining a 
priority of its own by monitoring each active group control means and for 
scheduling load distribution and assignment of group control processes on 
the basis of the determined priority, a third process for performing 
evaluation calculations in units of cars for hall-call assignment on the 
basis of each car information, and a fourth process for instructing 
execution of the third process upon occurrence of a hall call, waiting an 
evaluation calculation result obtained by the execution of the third 
process, assigning an optimum car upon reception of the evaluation result 
from the third process, and generating an end instruction of the third 
process; and (c) communicating means for connecting the unit control means 
and the group control means to each other and between the group control 
means, and performing communication with each unit control means in a data 
field different from that for each group control means. 
With the above arrangement, each group control means monitors other group 
control means to determine load assignment of its own so as to distribute 
the group control load. When a hall call is made, a given group control 
means serving as the fourth process instructs execution of the third 
process for the hall call to other group control means through the 
communicating means and waits for evaluation results. Upon reception of 
the evaluation results by the other group control means, the other group 
control means execute the third process, calculate evaluations for 
hall-call assignment in units of cars from information representing 
present status of each car, and transmit the calculation results through 
the communicating means. This transmission is performed from a control 
means having a relatively smaller load. Upon reception of the evaluation 
results, the given group control means serving as the fourth process 
performs assignment of the optimum car and generates an end instruction of 
the third processes. All group control means which are performing the 
third processes terminate execution of the third processes. In this 
manner, any group control means which has an available processing capacity 
for the control load executes necessary processes for group control. A 
group control means which has a heavy load may be exempt from process 
execution in practice, thereby averaging the load. 
Since the communicating means communicates with each unit control means in 
a data field different from that for each group control means, the unit 
control means is not adversely affected by a failure of any group control 
means. For this reason, reliability of unit control can be improved. In 
addition, even if several group control means fail or are stopped, total 
group control is not adversely affected. 
In order to achieve the above object of the present invention, the present 
invention can also be constituted as follows. There is provided an 
apparatus for performing group control on a plurality of elevators 
operated for a plurality of floors, evaluating each elevator b a 
predetermined calculation in response to a hall call, selecting an optimum 
elevator, and assigning the selected elevator to the hall call in 
accordance with the evaluation result, comprising: (i) unit control means, 
arranged in units of elevator cars, for controlling unit control of each 
elevator car and inputting/outputting information associated with its own 
car; (ii) a plurality of group control means each having a first process 
for exchanging each car information, a second process for determining a 
priority of its own by monitoring each active group control means and for 
scheduling load distribution and assignment of processes including car 
assignment so as to assign average loads of group control in 
correspondence with the number of active group control means and the 
priority on the basis of the determined priority, a third process for 
performing evaluation calculations for hall-call assignment on the basis 
of information of each car of process assignment upon reception of an 
instruction and for sending back the evaluation result to an instruction 
source, and a fourth process for instructing execution of the third 
process upon occurrence of a hall call, waiting an evaluation calculation 
result obtained by the execution of the third process, assigning an 
optimum car upon reception of the evaluation result from the third 
process, and generating an end instruction of the third process; and (iii) 
communicating means for connecting the unit control means and the group 
control means to each other and between the group control means, and 
performing communication with each unit control means in a data field 
different from that for each group control means. 
With the above arrangement, each group control means monitors remaining 
group control means to detect its own priority and determines process 
assignment on its own side such that group control load assignment becomes 
average in correspondence with its own priority and the number of active 
group control means, the load assignment including car assignment. When a 
hall call is made, the group control means which detects the hall call 
first and has executed the fourth process instructs execution of the third 
processes for the hall call to all the group control means including 
itself, and waits for the evaluation results. Upon reception of the 
evaluation results by the group control means which detects the hall call 
first, the remaining group control means execute the third processes and 
perform evaluation calculations for hall-call assignment of their cars on 
the basis of the information of the cars assigned to these group control 
means. The evaluation results are sent from each group control means to 
all the group control means except for itself. Upon reception of the 
evaluation results for the respective cars, the group control means which 
performs the fourth process performs assignment of the optimum car and 
informs the assigned optimum car to the corresponding unit control means 
through the communicating means. 
Each group control means is assigned with the process in accordance with 
the number of active group control means and its own priority. In 
addition, a given control means which performs a job (process) upon 
generation of a hall call causes other group control means to perform 
evaluation calculations, and performs optimal car assignment upon 
reception of the evaluation results. Therefore, the control loads are 
distributed to the respective group control means. In addition, each group 
control means monitors the remaining group control means to autonomously 
determine its own process, thereby distributing and averaging the load and 
hence averaging the control load. If even one of the group control means 
is operated, group control can be performed, thereby assuring reliability 
in this respect Furthermore, the communicating means communicates with 
each unit control means in a data field different from that for each group 
control means. Therefore, even if a given group control means fails, the 
unit control means is not adversely affected by data communication, 
thereby improving reliability of unit control.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Prior to a description of a preferred embodiment of the present invention, 
the basic concept of the present invention will be described with 
reference to FIG. 9. N elevator car unit controllers 11-l to 11-n for 
controlling a unit control function in a one-to-one correspondence with 
the elevator cars are connected to group controllers 10-l to 10-m, which 
control the group control function for performing scheduling management by 
active systems and which are determined by a system load, through 
high-speed transmission system TL1 having equal transmission/reception 
priorities. A group control function system (10-l to 10-m) is connected to 
a total system (10-l to 10-m and 11-l to 11-n) including the unit and 
group control functions through another high-speed transmission system 
TL2. These two hierarchical data fields (FIGS. 10A and 10B) are 
synthesized into one communication system. 
m group controllers 10-l to 10-m are connected in parallel with each other 
through hall-call transmission system TL2 different from high-speed 
transmission system TL1. Respective group controllers 10-l to 10-m have 
functions for assigning scheduling control functions of the processes of 
the group control function to the corresponding computers. With this 
arrangement, each process is divided into the hall-call unit common 
management function and No. l to No. n car unit control functions. These 
divided functions are controlled by the operating system of each computer. 
m group controllers 10-l to 10-m for controlling the group control function 
on-line monitor the number of active group control systems through the 
data field of the group control system. Respective group controllers 10-l 
to 10-m independently perfOrm scheduling of an event of the group control 
function by rechecking processing upon generation of a hall call or long 
waiting of a given hall call. Respective group controllers 10-l to 10-m 
are assigned with processes to allow load distribution in accordance with 
the number of active elevator cars. 
Group controllers 10-l to 10-m execute their own assigned processes through 
the data field of the group control system in accordance with the divided 
process assignment upon generation of an event of hall-call assignment. 
The job (process) in units of hall calls is performed by a plurality of 
computers in a cooperative manner. 
Unit controllers 11-l to 11-n arranged in a one-to-one correspondence with 
the elevator cars autonomously perform inputs/outputs through the total 
system data field asynchronous with the group control system data field 
Respective unit controllers 11-l to 11-n select information of their own 
cars for a hall call in accordance with information of each responded car 
determined by the group control system (10-l to 10-m) and on the above 
data field, and perform their own unit control functions by using the 
selected information as hall-call control information. 
As described above, the hall-call unit group control function for each hall 
call is divided into (n+1) rearrangeable control processes by the n 
controllers (11-l to 11-n), and the loads are assigned to the m group 
control systems (10-l to 10-m) in accordance with their active/inactive 
states. A series of group control functions can be realized by the data 
input/output with respect to the data field of the group control system 
(10-l to 10-m). Unit designation information mainly including the 
hall-call response information determined by the group control function is 
supplied to respective unit controllers 11-l to 11-n through the data 
field of the total system. The unit control systems (11-l to 11-n) can 
perform their own control functions through the data field which is a 
single transmission system but has a hierarchical structure. This 
operation is performed without being influenced by the loads of the group 
control system (10-l to 10-m). 
The group control systems can perform assignment of the respective process 
loads in accordance with the active/inactive states of m group controllers 
10-l to 10-m. Therefore, high-reliability and high system efficiency can 
be achieved, and cooperative distributed control between the computers of 
the group controllers can be achieved. 
N elevator car unit controllers 11-l to 11-n for controlling a unit control 
function in a one-to-one correspondence with the elevator cars are 
connected to group controllers 10-l to 10-m, which control the group 
control function for performing scheduling management by active systems 
and which are determined by a system load, through high-speed transmission 
system TL1 having a given transmission/reception priority. A group control 
function system (10-l to 10-m) is connected to a total system (10-l to 
10-m and 11-l to 11-n) including the unit and group control functions 
through another high-speed transmission system TL2. These two hierarchical 
data fields (FIGS. 10A and 10B) are synthesized into one communication 
system. 
Group controllers 10-l to 10-m are connected in parallel with each other 
through hall-call transmission system TL2 different from high-speed 
transmission system TL1. The group control function is divided into 
processes of n elevator car unit group control functions. Respective 
controllers 10-l to 10-m autonomously determine process assignment by the 
scheduling control function. Controllers 10-l to 10-m are managed by the 
operating systems of the computers, so that these controllers 10-l to 10-m 
autonomously determine a response to a hall call in a cooperative manner. 
In the same manner as in the nm (n+1) systems, m group controllers 10-l to 
10-m for controlling the group control function on-line monitor the number 
of active group control systems through the data field of the group 
control system. Respective group controllers 10-l to 10-m independently 
perform scheduling of an event of the group control function by rechecking 
processing upon generation of a hall call or long waiting of a given hall 
call. Respective group controllers 10-l to 10-m are assigned with 
processes to allow load distribution in accordance with the number of 
active elevator cars. 
The group control function for each hall call is divided into control 
processes which can be rearranged into n systems by n elevators, and the 
loads are assigned to the m group control systems (10-l to 10-m) in 
accordance with their active/inactive states. A series of group control 
functions can be realized by the data input/output with respect to the 
data field of the group control system (10-l to 10-m). Unit designation 
information mainly including the hall-call response information determined 
by the group control function is supplied to respective unit controllers 
11-l to 11-n through the data field of the total system. The unit control 
systems (11-l to 11-n) can perform their own control functions through the 
data field which is a single transmission system but has a hierarchical 
structure. This operation is performed without being influenced by the 
loads of the group control system (10-l to 10-m). 
The group control systems can perform assignment of the respective process 
loads in accordance with the active/inactive states of m group controllers 
10-l to 10-m. Therefore, high-reliability and high system efficiency can 
be achieved, and cooperative distributed control between the computers of 
the group controllers can be achieved. 
An embodiment of the present invention using n elevators will be described 
with reference to the accompanying drawings. FIG. 1 is a block diagram 
showing a system for performing group control on n elevators. 
Referring to FIG. 1, reference numerals 10-l to 10-m denote m group 
controllers which are subjected to distributed control. Reference numerals 
11-l to 11-n denote n elevator car unit controllers arranged in a 
one-to-one correspondence with the elevator cars to control operation 
control functions of the elevator car units. These controllers are 
constituted by high-performance small computers such as microcomputers and 
are operated under management of software stored in each controller. 
Group controllers 10-l to 10-m and elevator car unit controllers 11-l to 
11-n are connected to high-speed transmission system 1 for obtaining an 
equal transmission/reception priorities. The respective controllers (10-l 
to 10-m and 11-l to 11-n) can communicate with each other through this 
transmission system 1. The data fields of two systems each having a 
hierarchical structure described above are formed on high-speed 
transmission system 1. The group control functions mainly including the 
hall-call assignment function are performed by cooperation between the 
controllers (10-l to 10-m and 11-l to 11-n) by using the group control 
system (10-l to 10-m) data field and the total system (10-l to 10-m and 
11-l to 11-n) data field including group management and unit controllers. 
Low-speed transmission system 2 is a transmission control system for 
transmitting information transmitted through an elevator path such as call 
button 3 on each hall and can have a transmission speed lower than that of 
high-speed transmission system 1 because the volume of data communication 
on transmission system 2 is limited. Transmission system 2 is connected in 
parallel with group controllers 10-l to 10-m for controlling hall calls. 
Group controllers 10-l to 10-m can perform equal input/output management 
of hall-call information through system 2. 
FIG. 2A is a system configuration showing an embodiment of a software 
system having group controllers 10-l to 10-m according to the present 
invention. 
As shown in FIG. 2A, each of m group controllers 10-l to 10-m for 
controlling the group control function comprises (n+1) processes 
consisting of common manager M1 having a hall-call unit sync control 
function, and n car control managers M3-l to M3-n having car control 
functions. With this arrangement, each job having a hall-call assignment 
function in units of hall calls is performed for n group controllers. 
The (n+1) processes perform process assignment for m group controllers 10-l 
to 10-m shown in FIG. 1 by scheduling manager M2 so that the load 
processes of the group control system are equally assigned to the (n+1) 
systems. 
Scheduling manager M2 has an arrangement for on-line monitoring the active 
group control systems by group control system data fields (to be described 
later with reference to FIGS. 10A and 10B) through high-speed transmission 
system 1. Scheduling manager M2 has a function for automatically 
performing optimum load distribution of the instantaneously changing 
hall-call assignment job in the present status in real time. 
No. l to No. n car control managers M3-l to M3-n share one processing 
algorithm but have independent control areas in units of cars. This 
algorithm has processes registered as independent tasks in real time 
operating system M0. 
Common manager M1 having the hall-call sync control function primarily has 
a control function for performing sync control of the processes of group 
controllers 10-l to 10-m which are distributed into m systems. Common 
manager M1 has an arrangement which can support message reception queues 
from a plurality of sources and satisfies basic interprocess sync support 
functions such as a time-out function by time management and a retry 
request by an NAC (Negative Acknowledge Character) response. The contents 
of the algorithms used in units of hall calls are identical but have 
independent control areas. These algorithms are processes which can 
independently manage hall-call and recheck jobs which are simultaneously 
requested. 
FIG. 3 is a block diagram showing a hardware system configuration of 
high-speed transmission system 1 in FIG. 1. Transmission control is 
performed using microprocessing unit (MPU) 5. An arrangement for 
controlling a data link hierarchical structure complying with a LAN 
network model hierarchical structure proposed by the ISO (International 
Standards Organization) is constituted by data link controller (DLC) 6 and 
media access controller (MAC) 7, both of which are hardware arrangements. 
Therefore, highly intelligent data transmission can be performed, and a 
transmission control software load managed by microprocessing unit 5 for 
high-speed transmission control can be reduced. 
For example, an LSI i82586 available from INTEL Corp., U.S.A. can be used 
as data link controller 6 as a controller for performing highly 
intelligent transmission control. An i82501 available from INTEL Corp., 
U.S.A. can be used as the media access controller. By using these LSIs, 
high-speed transmission at a rate of 10Mbps can be relatively easily 
performed while the load of microprocessing unit 5 can be reduced. 
Reference numeral 9 denotes a system bus; 8, a control line; and 100, a 
serial transmission system connected to transmission system 1. 
The operation of the transmission control system for performing 
interprocess communication between the controllers will be described with 
reference to FIGS. 4 to 9. 
FIG. 4 is a block diagram showing a system of a theoretical transmission 
line in high-speed transmission system 1 in FIG. 1. FIG. 5 is a system 
diagram showing theoretical transmission connections between ports in FIG. 
4. 
FIG. 6 is a view showing an operation of a transmission control system 
shown in FIGS. 4 and 5. FIGS. 7 and 8 are flow charts showing detailed 
operations of primary station processing and secondary station processing 
in interprocess communication of user tasks. 
As shown in the system block of FIG. 4, N logical transmission lines are 
assumed on a physical common transmission line. The tasks in each station 
communicate with those in another station through N ports respectively set 
for the logical communication lines. Therefore, although physical 
communication line PL which connect the stations is constituted by one 
system, each station can perform parallel processing corresponding to the 
number of ports, i.e., N tasks if the number of ports is N. In this case, 
the operations of the transmission/reception queues of the tasks can be 
independently managed. 
The transmission/reception operations from the respective task are shown in 
FIG. 6. A transmission queue requested as a queue signal by a local 
processing function as a primary station function of each task is formed 
by a transmission control management table in units of port numbers. 
In a remote processing function as a secondary station function, a 
reception queue as a reception request is controlled and formed by each 
transmission control management table. A transmission output to physical 
common transmission line PL and an input received from physical common 
transmission line PL are temporarily buffered as transmission packets in 
the form of input and output queues. This buffering is managed by the 
transmission controller. Transmission/reception control with respect to 
physical common transmission line PL is performed without control of the 
CPU. 
A detailed operation of intertask communication will be described in detail 
with reference to FIGS. 7 and 8. 
In the primary station function task for performing a transmission request, 
ports of a transmission source are set for a transmission control task. 
Port Nos. SPORT and DPORT of the source and destination sources are 
designated. Primary station processing in station 110a corresponds to the 
operation shown in FIG. 7. The source station port No. corresponds to 
transmission port 12a, and the destination station port No. corresponds to 
reception port 13b. 
More specifically, when the primary station function task is executed in 
FIG. 7, the port Nos. of source and destination stations SPORT and DPORT 
are designated (S1), and transmission to the transmission control task for 
source station port 12a is requested (S2). When the transmission is 
requested, the transmission queue of the corresponding source station port 
No. in FIG. 6 is queued. Transmission output processing is executed by the 
transmission queue to form a transmission packet, and the transmission 
packet causes queueing of the output queue. The transmission packet is 
under the management of the transmission controller. Therefore, the 
primary station processing task waits an end status from the transmission 
control task (S3). The present task is temporarily interrupted, and 
control is shifted to the OS scheduler. If another task for a transmission 
request is present and this task has an occupying right of the CPU, the 
right is shifted to this task. 
The transmission packet is sent onto physical common transmission line PL 
by the transmission controller having management upon queueing. 
Thereafter, when the end status is set by the transmission control task, 
the present task is restarted and checks the status (S4). The present task 
waits reception of return data from the designation station for the source 
station port No. (S5). When the transmission packet is output onto the 
physical common transmission line, reception processing is executed in the 
designation station (S6). 
FIG. 8 shows secondary station processing corresponding to the primary 
station processing shown in FIG. 7. This secondary station processing 
corresponds to that of station 110b in FIG. 5. 
A logical transmission line is connected at reception port 12b 
corresponding to the destination station port No. DPORT. The operation of 
the transmission packet is shown in FIG. 6. When the transmission packet 
is received through physical common transmission line PL, the packet is 
queued as an input queue. The source and destination port Nos. are read by 
the transmission control task via received input processing. The read 
value is queued as a reception queue corresponding to the corresponding 
port No. DPORT, thereby connecting primary station processing to secondary 
station processing. 
In this secondary station processing, the station waits a message from the 
transmission control task (ST11). Secondary station processing is started 
in response to reception of the message and reads in the source and 
destination station port Nos. (ST12). Message data is decoded and 
application processing is performed based on the decoded message (ST13). 
Thereafter, the DPORT as the destination station port No. at the time of 
data input is used as a source station port No., and the source station 
port No. at the time of data input is used as the destination station port 
No. (ST14). A packet is sent to the transmission control task to request 
return transmission to the transmission control task (ST15). This 
transmission flow corresponds to return transmission from reception port 
PORT 13b to transmission port PORT 12a in FIG. 5. This operation indicates 
that return transmission is performed by the port No. received by the 
secondary station for the port No. sent from the primary station. 
The task waits an end status from the transmission control task (ST16). The 
task is restarted in response to an end status and checks a status (ST17), 
thereby completing secondary station processing. 
A return transmission packet is output by an output queue in secondary 
station processing of secondary station 110b and is received in primary 
station processing of primary station 110a. When the received packet is 
queued into the input queue, transmission port 12a of primary station 110a 
is designated by the secondary station at the time of return transmission. 
For this reason, this return transmission is input to the port 
corresponding to transmission port 12a. The return transmission input port 
coincides with a source port at which the primary station task is set in 
the wait status. The primary station processing task which waits return 
data from the destination station to source port 12a is restarted. 
Received data input and processing are performed, and primary station 
processing is completed. 
When the source and destination station port Nos. are designated at the 
time of data transmission from the source side, primary station processing 
is correlated to secondary station processing between the controllers. 
Therefore, the controllers are connected through theoretical or logical 
communication lines, and intertask communication through the logical 
communication lines can be realized. Although physical transmission line 
PL is one, a plurality of logical transmission lines can be set on 
physical common transmission line PL. Therefore, high-speed transmission 
(10 Mbps) can be performed. When a plurality of tasks shown in FIGS. 7 and 
8 are present and simultaneously performed, parallel intertask 
communication can be performed in real time independently of tasks at 
other ports. That is, a queue as in the case of a single port is not 
generated. Parallel intertask communication can be performed to achieve 
high-speed communication. 
An operation of a group management distributed control system having an 
autonomous function through a high-speed transmission system capable of 
supporting interprocess communication will be described below. 
FIGS. 9 and 10A to 10E show a broadcast communication system of a data 
field having a hierarchical structure created in high-speed transmission 
system 1, and information data thereof. Group controllers 10-l to 10-m 
form an m-system group control data field (FIG. 10B) for performing a 
group control function whose scheduling can be managed by active systems 
and a total system data field (FIG. 10A) also including a unit control 
function on the high-speed common transmission system which can be managed 
by a plurality of logical transmission lines. 
Group controllers 10-l to 10-m have an arrangement for 
input/output-accessing the two-system (TL1 and TL2) data fields Elevator 
car unit controllers 11-l to 11-n are not assigned with processes of the 
group control function. For this reason, elevator car unit controllers 
11-l to 11-n perform input/output access of only the limited data fields 
of response assignment information obtained as a result of process 
scheduling 
function of the m group controllers 10-l to 10-m and information of each 
car serving as base data of the car unit control process. 
The data fields are shown in FIGS. 10A and 10B. FIG. 10A shows a total 
system data field, and FIG. 10B shows a group control system data field. 
As described above, the total system data field (FIG. 10A) is limited to 
the response assignment information and car information required in units 
of cars. Therefore, the elevator car unit controllers a system-down of 
which is decisive and which are normally required large-capacity 
communication for distributed control require a minimum volume of data 
communication. The minimum volume of data communication and distributed 
processing can eliminate local overloading caused by group control 
function which tends to cause a complicated, heavy computer load. 
Therefore, reliability of the elevator car controllers can be improved. 
Elevator status information of n elevators of n groups are sent on the 
total system data field (FIG. 10A). Elevator car unit controllers 11-l to 
11-n for controlling the car unit control processes have equal assignment 
rights for m group controllers 10-l to 10-m. 
The group control system data field is divided into fields of common 
information (i), n-system car control management information (ii), and 
m-system group control management information (iii). The fields of 
information (i) and the information (ii) serve as fields exchanged by 
(n+1) control processes for an event of a hall call. The field of group 
control management information (iii) is a field used for scheduling 
management for averaging and assigning the plurality of processes for 
hall-call assignment jogs to the controllers. 
FIG. 10C shows an elevator status table of No. i (l.gtoreq.i .gtoreq.n) car 
in the data field of FIG. 10A. This table includes a cage position table 
showing the cage position of No. i car, a cage destination table 
representing a traveling direction of the cage, a cage weight table 
representing a load of the cage. a door status table representing whether 
the door of this cage is open or closed, and a cage-call registration 
status table representing whether a cage call is made and the floor at 
which the cage call is made if it is detected. 
FIG. 10D shows a response control table of No. i car in the data field of 
FIG. 10A. This table includes a hall-call assignment instruction table for 
instructing assignment of No. i car to a specific floor when the No. i car 
is determined to be responded to the generated hall call, and for 
indicating the condition of a hall call to which the assignment has been 
completed; a distribution wait instruction table for instructing a wait 
when a condition for performing the distribution wait is established; a 
specific floor return instruction table for storing instructions required 
for returning the cage to a specific floor; and a reference floor 
forerunner instruction table for storing instructions for determining 
which cage is a forerunner when a plurality of cages wait at the reference 
floor such as a first-floor lobby. 
FIG. 10E shows a common information table in the data field shown in FIG. 
10B. This table includes a hall-call registration status table which 
represents hall-call registration status, a traffic status table 
representing a flow of traffic (flow of trafic demand) of whole elevator 
system, and an estimation parameter status table representing a control 
parameter status of estimation operation (to be described later with 
reference to FIG. 14). 
A No. m car data table for estimation, a No. m car predicted arrival time 
table, and the like of the data field shown in FIG. 10B are disclosed in 
the following U.S. patent together with evaluation calculations: 
U.S. Pat. No. 4,760,896 patented on Aug. 2, 1989, titled "Apparatus for 
Performing Group Control on Elevators" invented by Yamaguchi. All 
disclosed contents of this U.S. patent are incorporated in the 
specification of the present application. 
The arrangements of FIGS. 3 to 6 of the present application are also 
disclosed in U.S.S.N. 101,135 filed on Sept. 25, 1987, titled "Information 
Transmission Control Apparatus for Elevator System" invented by the 
present inventor. All disclosed contents of this U.S. application are also 
incorporated in the specification of the present application. 
FIG. 11 is a flow chart showing a scheduling control operation of the 
arrangement in FIG. 2A. FIG. 12 is a view showing an interprocess control 
operation of (n+1) divided processes after scheduling management is 
completed and the respective processes are assigned. FIG. 13 is a flow 
chart showing an operation of a hall-call unit sync control function as 
one of a plurality of processes of the present invention, and FIG. 14 is a 
flow chart showing an operation of a car control function as another one 
of the plurality of processes of the present invention. 
As shown in the flow chart of FIG. 11, m group controllers 10-l to 10-m 
perform on-line load assignment of (n+1) processes in real time. In order 
to execute load division, the number of active systems (e.g., 5 systems) 
out of m systems (e.g., 8 systems) is monitored by monitoring the data 
field (FIG. 10B) of the group control systems to calculate number m1 of 
control systems to which the group control functions are assigned. Average 
load N =(n+1)/m1 assigned to (n+1) control processes of the hall-call unit 
sync control management process and No. l to No. n car control management 
processes which are obtained by dividing the hall-call assignment control 
function into the plurality of processes is calculated (S21). For example, 
if n=8 and m1=5, N=9/5=1/8. A fractional part is rounded off to obtain 
N=1. 
Unassigned load M of the process which is represented by a remainder of the 
division of (n+1)/m1 is calculated (S22). For example, if n=8 and m1 =5, 
the remainder of (n+1)m1 is given as 4. Priorities Pm of the group 
controllers (m1=1 to 5) determined to be active by the above monitoring in 
units of their own system numbers (e.g., 1, 2, 3, 4, and 5) in l to m 
group controllers 10-l to 10-m are calculated (S23). The priority is 
determined solely when the loads on the hall-call unit sync control 
process and the No. l to No. n car control processes are equal to each 
other. The control processes (5 processes) as the average load processes 
are assigned to m active group controllers m1 (=5) in accordance with 
their own CPU priorities Pm (S24). For example, if one average load 
process has one point, one point is assigned to each of the five active 
systems. 
The number m of systems is not fixed to a predetermined value and all the m 
systems are not always normally operated. For these reasons, all process 
assignment is not always completed by assignment of processes to m1 (=5) 
systems. 
The unassigned M (4 systems) load processes are compared with calculated 
priority Pm of the own CPU. If a process to be assigned to each of the M 
systems is present (i.e., if YES in step S25), the unassigned process (one 
point) is assigned in addition to the average load (one point) to the 
corresponding one of the M systems in the same manner as in the assignment 
algorithm (S21) of the average load algorithm (S26). 
For example, assume that a group control of five systems (m1 =5) for the 
eight (n =8) elevators is in active, and that higher priorities are 
assigned to the system having smaller numbers. Each average load assigned 
to No. 1 to No. 5 systems is given as one point (S21). In this case, 
unassigned processes are given as 4 points (M =4) (S22). These unassigned 
processes are additionally assigned to No. 1 to No. 4 systems, 
respectively, in accordance with their priorities. In this case, the load 
processes assigned to each of No. 1 to No. 4 systems are two points, while 
the load process assigned to No. 5 system is kept to be one point. In this 
manner, load distribution in group control is automatically performed. 
That is, the (n+1) control processes for each hall call are assigned to m 
group controllers in accordance with their degrees of operations. 
According to the scheduling management of the algorithm shown in the flow 
of FIG. 11, since no predetermined relationship is established between the 
m group controllers and n elevators, the number of systems can be 
arbitrarily set in accordance with the number of floors, the grades of 
elevator models, and a total system load of the group controllers. In 
addition, if at least one of the m systems is operated, a total function 
can be normally performed. 
The (n+1) processes assigned to the m1 active systems by the above 
scheduling management are controlled in units of hall calls. In an event 
of generation of a hall call or rechecking caused by long-period waiting, 
a series of processes are correlated through the group control system data 
field while process control is synchronized by the hall-call unit sync 
management process, as shown in FIG. 12. The group control function as 
hall-call assignment is systematically performed in the m1 group 
controllers. 
Start management of a hall-call assignment job is performed by a sync 
management process flow chart in FIG. 13. Process starting of the 
controllers to which No. l to No. n car unit processes are assigned is 
performed through the group control system data field. 
A request for the group control process of Nos. l to n cars is started 
(S31), and management from the group control process of Nos. l to n cars 
is return-waited (S32). 
The group control process of each car which is started by the start request 
in step S31 is performed by process processing in accordance with the flow 
chart in FIG. 14. Starting is performed in response to an instruction of 
sync management process (S41). Information of the target elevator car is 
input from the data field (FIG. 10A) of the total system (S42). An 
estimation calculation is performed for the target car based on the input 
information (S43). The result is returned to the sync management process 
(S44). 
Upon reception return transmission, the sync management process (FIG. 13) 
determines an optimum car to which the response is assigned on the basis 
of the evaluation result (S33). At the same time, process end management 
is executed for all group control processes. After synchronization is 
established, the information of the optimum system obtained in step S33 is 
transmitted to the data field of the total system (S34). 
The response car data information corresponding to hall-call assignment as 
the event is sent to all unit controllers 11-l to 11-n. The unit 
controller of the car to which the response is assigned controls to 
satisfy the corresponding hall call on the basis of the response car data 
information. When transmission is completed in step S34, the sync 
management process (FIG. 13) completes the hall-call assignment job and 
monitors the next event. 
As described above, the assignment control function is regarded as one job 
in units of hall calls, the job is divided into one process for managing 
sync control of this job and n processes for n elevators for performing 
car unit control. The (n+1) processes are assigned to m group controllers 
10-l to 10-n by the scheduling management mechanism in accordance with 
their active/inactive states so as to equal load assignment. The plurality 
of processes assigned by one process for managing the sync control of the 
job are correlated 
through the data field of the group control system Therefore, group 
controllers 10-l to 10-m execute the group control function as a hall-call 
assignment in a cooperative manner. The group management loads are 
automatically and always distributed in accordance with the 
active/inactive states, thereby creating a flexible distributed control 
system free from the centralized management mechanism. The group control 
system can be arranged not on the basis of the number of elevators and 
their models, but on the basis of the control function of the control 
system, i.e., the computer processing capacity. 
The communication line different from that of the group control system is 
arranged by the hierarchical data field structures, and the unit control 
systems are free from the operations of the group control systems, thereby 
improving system reliability. As a result, reliability of the unit control 
systems can be improved A variable load distribution function based on the 
active/inactive states of the controllers can allow improvement of 
reliability of the group control system. 
The present invention is not limited to the particular embodiment described 
above. Various changes and modifications may be made without departing 
from the spirit and scope of the invention. 
FIG. 2B shows a system configuration of a software system of group 
controllers 10-l to 10-m according to another embodiment of the present 
invention. Each of m group controllers 10-l to 10-m for controlling the 
group control function comprises sync manager MIS having a hall-call unit 
sync control function for each hall-call assignment function job in units 
of hall calls for n controllers, and No. 1 car to No. n control managers 
M3-l to M3-n having unit sync control functions of the respective cars. 
The n processes are assigned to m group controllers 10-l to 10-m shown in 
FIG. 1 by scheduling manager M2 such that the group control system load 
processes are equal to each other in accordance with the number of active 
controllers. 
Scheduling manager M2 has an arrangement for on-line monitoring the active 
group control systems by the data field of the group control system via 
high-speed transmission system 1 shown in FIG. 1. Manager M2 has a 
function for automatically performing optimum real-time load distribution 
in the present status for each of randomly generated call assignment jobs. 
No. l to n control managers M3-l to M3-n have identical processing 
algorithms and their control areas are independent of each other in units 
of cars. Processes as independent tasks are registered in real-time 
operating system M0. Upon data exchange with the data field of the group 
control system, this operating system M0 autonomously determines whether a 
corresponding car can respond to a hall call generated under the sync 
control of sync manager MIS. 
Sync manager MIS having a hall-call sync control function performs 
start/abort management of the No. l to n car control manager processes 
executed by m distributed group controllers 10-l to 10-m. Sync manager MIS 
matches a timing of each hall call for group controllers 10-l to 10-m for 
performing independent and asynchronous parallel operations for n systems 
and assigned to the m computers. At the same time, manager MIS has an 
arrangement for transmitting a message to a plurality of tasks and 
supporting message reception wait management. Manager MIS has a basic 
management function for supporting a sync function for each hall-call 
execution unit in independent and asynchronous parallel processes such as 
a time-out process by time management and an abort process by task 
monitoring. In addition, manager MIS also serves as a management mechanism 
for performing queueing management for a request having a priority in 
hall-call generation jobs and a long-period wait recheck jobs which are 
asynchronously and independently generated. 
The content of the data field of the total system is limited, as shown in 
FIG. 10A. The influences of the complex group control function for 
performing large-capacity data communication by distributed control and 
requiring a large computer load on elevator car unit controllers 11-l to 
11-n a system-down of which is decisive can be eliminated to improve 
reliability of elevator car unit controllers 11-l to 11-n. 
Elevator status information of n elevators of n systems is sent on the data 
field of the total system. Therefore, the assignment rights of the 
elevator car unit controllers for controlling elevator car unit control 
processes are equally assigned to m group controllers 10-l to 10-m. 
The data field of the group control system used in the arrangement of FIG. 
2B is the same as that in FIG. 2A. This data field is classified into a 
data field of common information (i), a data field of n car control 
information (ii), m group control information (iii). The fields of the 
information (i) and the information (ii) are information fields which are 
exchanged between the n divided control processes in each event such as a 
hall-call unit assignment job. The field of information (iii) is an 
information field used for the scheduling management for averaging and 
assigning the plurality of processes for the call assignment jobs in the 
respective controllers. 
FIG. 16 is a flow chart showing a scheduling management operation according 
to the present invention. n+1 in FIG. 11 is replaced with n in FIG. 16. 
FIG. 17 is a flow chart showing a control operation of the sync manager of 
the present invention. FIG. 18 is a flow chart showing an operation of 
each process in the car control manager according to the present 
invention. FIG. 19 is an operational block diagram showing status 
transition of each process of the sync manager and car control manager in 
each CPU (m.sub.l to m.sub.m) in each of m group controllers 10-l to 10-m 
of the present invention. 
As shown in the flow chart of FIG. 16, m group controllers 10-l to 10-m 
perform on-line process load assignment of n systems. In order to execute 
load assignment, the number of m active systems is monitored by monitoring 
the data field of the group control system, and the number of control 
systems assigned to the group control functions is calculated. Average 
assignment load N of loads assigned to n processes of the No. l to n 
control managers which are obtained by dividing the hall-call assignment 
control function into a plurality of processes for the calculated systems 
is calculated (S51). Unassigned load M of the processes is then calculated 
(S52). 
The own system numbers of the m group controllers and own CPU priorities Pm 
in the active systems are calculated or determined (S53). More 
specifically, the control processes of the No. l to n car control 
processes are regarded as equal loads, and priorities Pm are solely 
determined. The control process as the average load process is assigned to 
the corresponding controller in accordance with own CPU priority Pm (S54 
to S56). The control processes corresponding to the priorities are 
assigned to the m1 active systems in the m systems. 
The number of m systems according to the present invention is not a fixed 
number and all the m systems are not always normally operated. All process 
assignment is not always completed by assignment of the above-mentioned 
processes. For this reason, the unassigned M load processes are compared 
with the calculated priority Pm of the own CPU. If a process to be 
assigned to each of the M systems is present, the unassigned process is 
assigned in addition to the average load to the corresponding one of the M 
systems in the same manner as in the assignment algorithm of the average 
load algorithm. The n control processes for each hall call are 
autonomously assigned to m group controllers 10-l to 10-m in accordance 
with their degrees of operations. 
According to scheduling management by the algorithm shown in the flow of 
FIG. 16, since no predetermined relationship between the m group control 
systems and the n elevators is established, the number of group control 
systems can be arbitrarily set in accordance with the number of floors, 
the grades of elevator models, and the like. In addition, if at least one 
of the m systems is normally operated, the total function can be 
satisfied. 
The plurality of n processes assigned to the active systems by the 
scheduling management are controlled in units of hall calls. The flow of 
FIG. 17 is executed in an event such as generation of a hall call and 
long-period wait rechecking. More specifically, each of the sync managers 
in m group controllers 10-l to 10-m (No. l to m systems are active) waits 
a hall-call job request from its own controller 10-i or from controllers 
to 10-m other than controller 10-i in an order of controllers from the 
controller which detects the hall-call request job first (S61). 
When a hall-call job is requested, each of the m sync managers requests 
start to an assigned process of its own controller 10-i which is selected 
from the n car unit processes assigned to CPUs in accordance with the 
active status of the m group controllers (S62). The management for waiting 
completion of the assigned process of its own controller 10-i is performed 
(S63). 
Each car unit process is then executed in response to the start request in 
step S62. The CPU of this car calculates a car evaluation assigned to this 
car on the basis of the data from the data file of the total system (S71 
to S73). When evaluation calculations of the respective cars are 
completed, control is shifted to the sync manager of its own CPU (S74). 
The sync manager of its own CPU monitors completion of all car unit 
processes assigned to its own CPU and matches the timing for completion of 
load processing of its own CPU. 
Upon completion of all car unit processes assigned to the sync manager of 
its own CPU, the sync manager performs completion transmission to the sync 
managers of controllers 10-l to 10-m other than controller 10-i (S64). At 
the same time, the sync manager of its own CPU monitors completion of the 
No. l to n car unit processes (S65). Upon this completion, each of the 
sync managers of the m CPUs requests restart to the assigned process of 
its own controller 10-i (S66). The No. l to n car unit processes 
independently, asynchronously, and autonomously detect existence of 
responses from their own cars (S75 and S76). When the assigned car is 
detected as described above, information is transmitted to each unit 
controller through the data field of the total system. 
FIG. 19 shows a status transition chart of the operations of each 
controller of FIGS. 17 and 18. 
As described above, each sync manager of an active CPU in each of the m 
group controllers establishes synchronization of an asynchronously, 
independently input hall-call assignment job while the active CPUs 
communicate with each other. The active CPUs cooperate with each other, 
and the processes are independently executed while the loads are averaged 
(distributed) to the CPUs by the scheduling management. Therefore, the car 
unit processes (mainly evaluation calculations) serving as control loads 
are executed with a good balance in the total system. Each process 
independently detects the existence of the response of its own car, and 
the group control function can be performed as a whole. In addition, the 
car unit processes can be rearranged and executed in any of the m CPUs. 
Therefore, the m group control systems can serve as group control systems 
having autonomous controllability and autonomous cooperativeness. 
As described above, the assignment control function for each hall call is 
regarded as one job in this system. This job is divided into n-car, 
n-system processes for performing car unit control under the control of 
sync managers. The n processes are assigned to average the loads by the 
scheduling management mechanism in accordance with the active/inactive 
states of the m group controllers. The plurality of processes are 
correlated through the data field of the group control system. The group 
control function as hall-call assignment is performed while group 
controllers cooperate with each other. Therefore, the group control loads 
can be automatically distributed in accordance with the active/inactive 
states of the group controllers, thereby creating the flexible distributed 
control system without using the centralized management mechanism. It is 
possible to set the group control system not on the basis of the number of 
elevators and/or the elevator models, but on the basis of the control 
function of the control system, i.e., the computer processing capacity. 
Since the data fields have hierarchical structures, reliability of unit 
controllers can be improved. In addition, reliability of the group control 
system can also be improved by a variable load distribution function (cf. 
FIG. 11 or FIG. 16) based on the active states. 
The present invention is not limited to the particular embodiments 
described above. Various changes and modifications may be made without 
departing from the spirit and scope of the invention. 
According to the present invention as has been described above, the group 
control function is divided into a plurality of control processes in units 
of hall-call events. These control processes can be independently executed 
and can be rearranged. The process load assignment is automatically 
performed by the scheduling function in accordance with active control 
systems. Therefore, the control loads can be averaged and distributed, 
thereby creating a distributed group control system without using a 
centralized management mechanism. At the same time, a system-down due to a 
failure of some group control systems tends not to occur, so that it is 
possible to maintain cooperative control of the control systems. That is, 
flexibility and versatility are provided to the system which is fixed by 
the number of number of cars and the grades of the elevator models. 
Therefore, the system can be determined by the computer processing 
capacity. 
A system-down of the overall group control system by partial system-down 
can be prevented by cooperative control of the control systems. Therefore, 
reliability of the group management can be improved. In addition, no fixed 
relationship between each unit controller and each group controller is 
established, so that the unit controllers are not adversely affected by 
the group controllers. Reliability of unit controllers can be improved. 
On the other hand, according to the present invention, the group control 
function is divided into a plurality of control processes which can be 
independently executed and can be rearranged. Each group controller uses 
the scheduling function to automatically, independently, and autonomously 
perform process load assignment in accordance with the active control 
systems. The control loads are averaged and distributed, thereby creating 
a distributed group control system without using a centralized management 
mechanism. A system-down due to a failure of some group control systems 
tends not to occur, so that it is possible to maintain cooperative control 
of the control systems. That is, flexibility and versatility are provided 
to the system which is fixed by the number of number of cars and the 
grades of the elevator models. Therefore, the system can be determined by 
the computer processing capacity. A system-down of the overall group 
control systems by partial system-down can be prevented by cooperative 
control of the control systems. Therefore, reliability of the group 
management can be improved. In addition, no fixed relationship between 
each unit controller and each group controller is established, so that the 
unit controllers are not adversely affected by the group controllers. 
Reliability of unit controllers can be improved.