EP0348152A2
Expired / Lapsed
EP
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Queue based elevator dispatching system using peak period traffic prediction
Assignee: Otis Elevator Co
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Filing: 1989-06-20
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Granted: —
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Expires: 2009-06-20
Abstract
Abstract Elevator system with multiple cars ( 1-4 ) and a group controller ( 32 ) having signal processing means ( CPU ) controlling car dispatching from the lobby ( L ). During peak conditions (up-peak, down-peak and noontime), each car is dispatched and assigned to hall call floors having a large predicted number of passengers waiting on priority basis, resulting in queue length and waiting time at the lobby and upper floors being decreased, and system handling capacity increased. Estimations of future traffic flow levels for the floors for five minute intervals are made using traffic levels measured during the past few time intervals on that day as real time predictors, using a linear exponential smoothing model, and traffic levels measured during similar time intervals on previous similar days as historic traffic predictors, using a single exponential smoothing model. Combined prediction is used to assign hall calls to cars on priority basis for those floors having predicted high level of passenger traffic to limit maximum waiting time and car load. Noontime priority scheme is based on multiple queue sizes and percentages of maximum waiting time limits. Different waiting time limits can be used for lobby and above lobby up and down hall calls with automatic adjustment. During up-peak the lobby is given high priority. The lobby queue is predicted using passenger arrival rates and expected car arrival times. Down-peak operation uses multiple queue levels and percentages of waiting time limits, with estimated queues based on passenger arrival using car-to-hall-call travel time.
Inventors
- 👤 Kandasamy Thangavelu
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 13:11
CPC Classifications
B; B66; B66B; B66B1/00; B66B1/24; B66B1/2408; B66B1/2458; B66B2201/00; B66B2201/10; B66B2201/102; B66B2201/20; B66B2201/211; B66B2201/222; B66B2201/40; B66B2201/402; B66B2201/403
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
209 words
An elevator dispatcher for controlling the assignment of hall calls among a plurality of elevator cars serving a plurality of floors in a building in response to hall calls made during peak time conditions, in association with traffic volume measuring means for measuring the traffic volume on a per floor and per direction basis, characterized by: signal processing means for providing signals for determining when the system is in a peak time condition, such as up-peak, noontime and down-peak periods, and, when a peak time condition exists, for providing further signals - - for measuring and collecting passenger traffic data in the building and predicting passenger traffic levels as functions of time, a short period of time before the occurrence of the specific levels, said traffic data including at least that day's real time data of actual passenger traffic; - for determining if historic passenger traffic data is available for at least a past few days similar time period, and, if such historic passenger traffic data is available, including said historic passenger data in predicting passenger traffic levels; and - for assigning hall calls to the cars based on the expected passenger queue levels on a floor-by-floor basis and computed waiting time of hall calls in dispatching the cars.
Claim 2
Dependent Claim
209 words
An elevator dispatcher for controlling the assignment of hall calls among a plurality of elevator cars serving a plurality of floors in a building in response to hall calls made during peak time conditions, in association with traffic volume measuring means for measuring the traffic volume on a per floor and per direction basis, characterized by: signal processing means for providing signals for determining when the system is in a peak time condition, such as up-peak, noontime and down-peak periods, and, when a peak time condition exists, for providing further signals - - for measuring and collecting passenger traffic data in the building and predicting passenger traffic levels as functions of time, a short period of time before the occurrence of the specific levels, said traffic data including at least that day's real time data of actual passenger traffic; - for determining if historic passenger traffic data is available for at least a past few days similar time period, and, if such historic passenger traffic data is available, including said historic passenger data in predicting passenger traffic levels; and - for assigning hall calls to the cars based on the expected passenger queue levels on a floor-by-floor basis and computed waiting time of hall calls in dispatching the cars.
Claim 3
Dependent Claim
60 words
The elevator dispatcher according to Claim 1 , characterized in that said signal processing means further provides signals for: giving priority to the floors having more than a predicted large number of passengers waiting, by calculating the average number of people waiting for the hall calls at each floor and giving priority to long waiting times in dispatching the cars.
Claim 4
Dependent Claim
47 words
The elevator dispatcher according to Claim 1 or 2, characterized in that said signal processing means further provides signals for: providing multiple queue level values, with the floors having a queue level value greater than the queue level value of another floor being assigned a car sooner.
Claim 5
Dependent Claim
37 words
The elevator dispatcher according to Claim 1,2 or 3 characterized in that said signal processing means further provides signals for: assigning multiple cars to a hall call at a floor having a high predicted passenger traffic level.
Claim 6
Dependent Claim
80 words
The elevator dispatcher according to any preceding claim characterized in that said signal processing means further provides signals for: comparing the waiting time for all waiting hall calls against a preselected maximum allowed value, which may be different for up-peak, noon and down-peak periods and for lobby calls, up hall calls and down hall calls, and assigning on a high priority basis car(s) to any hall calls having waiting time values exceeding a value based on the preselected maximum value(s).
Claim 7
Dependent Claim
124 words
The elevator dispatcher according to any preceding Claim, wherein said traffic volume measuring means includes recording means for recording the number of people de-boarding each car and number of people boarding each car during peak conditions, characterized in that said signal processing means further provides signals for: collecting the number of passengers de-boarding the cars, number of people boarding the cars, number of hall call stops and number of car call stops made at each floor for cyclical short time intervals; and saving the past passenger de-boarding counts, passenger boarding counts, car hall call stop counts and car call stop counts at each floor for lobby generated and lobby oriented traffic in a data base to provide a recent past history of passenger volume.
Claim 8
Dependent Claim
73 words
The elevator dispatcher according to Claim 6 , characterized in that said signal processing means further provides signals for: predicting passenger de-boarding counts, passenger boarding counts, car hall call stop counts and car call stop counts at each floor for the next short time period of the order of no more than some few minutes using data collected for past like short time periods during that same day providing a real time prediction.
Claim 9
Dependent Claim
83 words
The elevator dispatcher according to Claim 6 or 7, wherein said recording means for recording the number of people de-boarding each car and the number of people boarding each car at least during peak conditions retains the recorded data for each day for at least a period of several similar days and produces historic predictions using the past several days, data, characterized in that said signal processing means further provides signals for: obtaining optimal predictions combining both real time predictions and historic predictions.
Claim 10
Dependent Claim
77 words
The elevator dispatcher according to Claim 8 , characterized in that said signal processing means further provides signals for: combining both real time predictions and historic predictions in accordance with the following relationship X = ax h + bx r where "X" is the combined prediction, "x h " is the historic prediction and "x r " is the real time prediction for the short time period for the floor, and "a" and "b" are multiplying factors.
Claim 11
Dependent Claim
33 words
The elevator dispatcher according to Claim 9 , wherein said multiplying factors added together equal unity and provide relative weighting between the historic prediction and the real time prediction in the combined prediction.
Claim 12
Dependent Claim
72 words
The elevator dispatcher according to Claim 9 or 10, wherein various values of said multiplying factors are provided in a look-up table and provide relative weighing between the historic prediction and the real time prediction in the combined prediction based on a comparison of the amount of error between predictions based on previously assigned values of "a" & "b" and actual observations over a relatively short time period of a few minutes.
Claim 13
Dependent Claim
30 words
The elevator dispatcher according to Claim 11 , wherein "b" is increased in value and "a" is decreased in value as the amount of error increases in the look-up table.
Claim 14
Dependent Claim
40 words
The elevator dispatcher according to any of Claims 8 to 12, characterized in that said historic prediction of passenger de-boarding counts for the next short time period of said signal processing means is based on: a single exponential smoothing model.
Claim 15
Dependent Claim
67 words
The elevator dispatcher according to any of Claims 7 to 13, characterized in that said prediction of passenger de-boarding counts for the next short time period of the order of no more than some few minutes using data collected for past like short time periods during that same day providing a real time prediction of said signal processing means is based on: a linear exponential smoothing model.
Claim 16
Dependent Claim
29 words
The l!evator dispatcher according to any of the preceding claims wherein said short time period is of the order of about a three (3) to five (5) minute interval.
Claim 17
Dependent Claim
41 words
The elevator dispatcher according to any preceding claim dependent on Claim 5, characterized in that said signal processing means further provides signals for: adjusting the maximum waiting time limits automatically based on the frequency of actual waiting time exceeding specified limits.
Claim 18
Dependent Claim
67 words
The elevator dispatcher according to any preceding claim, characterized in that said signal processing means further provides signals for: assigning hall calls to the cars also based on the expected load of the car after the hall call is answered; and computing the expected car load after the car answers a hall call and limiting the car load to a specified portion of the car's maximum capacity.
Claim 19
Dependent Claim
49 words
The elevator dispatcher according to any preceding claim, characterized in that said signal processing means further provides signals for: assigning hall calls to the cars based on giving long queues of waiting passengers at a hall call higher priority over longer waiting time for hall calls with shorter queues.
Claim 20
Dependent Claim
95 words
The elevator dispatcher according to any preceding claim, characterized in that said signal processing means further provides signals for: estimating the queue length at the lobby at the end of repeating intervals of a very short period of time of the order of some seconds based on the predicted arrival rate of people for each longer period of time of the order of a few minutes during an up-peak period; and adjusting the predicted queue length based on the car arrivals at the lobby and the passenger pick-up by arriving cars during an up-peak period.
Claim 21
Dependent Claim
61 words
The elevator dispatcher according to Claim 19 , characterized in that said signal processing means further provides signals for: giving priority to the lobby over hall calls above the lobby for a car if the expected lobby queue is greater than at least a predetermined level of car capacity of the order of about sixty-five (65%) percent, during an up-peak period.
Claim 22
Dependent Claim
56 words
The elevator dispatcher according to any preceding claim, characterized in that said signal processing means further provides signals for: when down-peak conditions are present, using multiple queue sizes and multiple percentages of waiting time limits for selecting multiple priorities, with the priorities being selected to minimize average wait time and maximum and variance of wait time.
Claim 23
Dependent Claim
28 words
The elevator dispatcher according to Claim 21 , characterized in that said signal processing means further provides signals for: giving down hall calls greater priority during down-peak conditions.
Claim 24
Dependent Claim
78 words
The elevator dispatcher according to any preceding claim, characterized in that said signal processing means further provides signals for: when an up-peak condition is present, assigning up hall calls first and then down hall calls; when a down-peak condition is present, assigning down hall calls and then up hall calls; and when a noontime condition is present, selecting the order of up and down hall call assignment based on lobby generated up traffic and lobby oriented down traffic.
Claim 25
Dependent Claim
33 words
The elevator dispatcher according to any preceding claim, characterized in that said signal processing means further provides signals for: computing the waiting time based on the actual waiting time of the hall calls.
Claim 26
Dependent Claim
33 words
The elevator dispatcher according to any preceding Claim, characterized in that said signal processing means further provides signals for: computing the waiting time based on the expected waiting time of the hall calls.
Claim 27
Dependent Claim
134 words
The elevator dispatcher according to any of Claims 1 to 25 , wherein said dispatcher is part of an elevator system, said system including - - a plurality of cars for transporting passengers from a main floor to a plurality of contiguous floors spaced from the main floor; - car call means, one associated with each of said cars, for entering car calls for each car; - car motion control means associated with said cars for moving each car in accordance with the assignment of the hall calls to the cars based on said signals from said signal processing means; and - traffic volume measuring means associated with said signal processing means for measuring the traffic volume on a per floor and per direction basis and providing that information to said signal processing means.
Claim 28
Independent Claim
395 words
A method for dispatching elevators from a main floor to other contiguous floors in a building, in association with traffic volume measuring means for measuring the traffic volume on a per floor and per direction basis at least during peak time conditions, in response to hall calls, comprising the following step(s): (a) utilizing - signal processing means for providing signals for determining when the system is in a peak condition, including clock means for determining calendar time with respect to at least the day of the week and the time of the day, and, at least when such peak condition exists, for providing further signals - - for measuring and collecting passenger traffic data in the building and predicting passenger traffic levels as functions of time, a short period of time before the occurrence of the specific levels, said traffic data including at least that day's real time data of actual passenger traffic; - for determining if historic passenger traffic data is available for at least a past few days, similar time period, and, if such historic passenger traffic data is available, including said historic passenger data in predicting passenger traffic levels; and - for assigning hall calls to the cars based on the expected passenger queue levels on a floor-by-floor basis and computed waiting time of the hall calls in dispatching the cars; (b) at least during peak conditions, utilizing said traffic volume measuring means to measure and collect passenger traffic data in the building a short period of time before the occurrence of the specific levels and, over the course of time, saving the data for at least several days in a data base encoded to at least the time of day the data was taken; and (c) utilizing said signal processing means for predicting passenger traffic levels for a short period of time before the occurrence of the specific level using at least that day's real time data of actual passenger traffic and determining if historic passenger traffic data is available for at least a past few days, similar time period, and, if such historic passenger traffic data is available, including said historic passenger data in predicting passenger traffic levels; and (d) assigning hall calls to the cars based on the expected passenger queue levels on a floor-by-floor basis and the computed waiting time of the hall calls in dispatching the cars.
Claim 29
Independent Claim
395 words
A method for dispatching elevators from a main floor to other contiguous floors in a building, in association with traffic volume measuring means for measuring the traffic volume on a per floor and per direction basis at least during peak time conditions, in response to hall calls, comprising the following step(s): (a) utilizing - signal processing means for providing signals for determining when the system is in a peak condition, including clock means for determining calendar time with respect to at least the day of the week and the time of the day, and, at least when such peak condition exists, for providing further signals - - for measuring and collecting passenger traffic data in the building and predicting passenger traffic levels as functions of time, a short period of time before the occurrence of the specific levels, said traffic data including at least that day's real time data of actual passenger traffic; - for determining if historic passenger traffic data is available for at least a past few days, similar time period, and, if such historic passenger traffic data is available, including said historic passenger data in predicting passenger traffic levels; and - for assigning hall calls to the cars based on the expected passenger queue levels on a floor-by-floor basis and computed waiting time of the hall calls in dispatching the cars; (b) at least during peak conditions, utilizing said traffic volume measuring means to measure and collect passenger traffic data in the building a short period of time before the occurrence of the specific levels and, over the course of time, saving the data for at least several days in a data base encoded to at least the time of day the data was taken; and (c) utilizing said signal processing means for predicting passenger traffic levels for a short period of time before the occurrence of the specific level using at least that day's real time data of actual passenger traffic and determining if historic passenger traffic data is available for at least a past few days, similar time period, and, if such historic passenger traffic data is available, including said historic passenger data in predicting passenger traffic levels; and (d) assigning hall calls to the cars based on the expected passenger queue levels on a floor-by-floor basis and the computed waiting time of the hall calls in dispatching the cars.
Claim 30
Dependent Claim
43 words
The method according to Claim 27 , characterized in that there is included step(s) analogous to the limitations defined in one or more of the dependent claims above or one or more of the other significant method steps disclosed in the foregoing specification.
References Cited (Backward Citations)
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