US3561571A

US3561571A - Elevator group supervisory control system

Info

Publication number: US3561571A
Application number: US592186A
Authority: US
Inventors: John A Gingrich
Original assignee: Dover Corp
Current assignee: Delaware Capital Formation Inc
Priority date: 1965-11-05
Filing date: 1966-11-04
Publication date: 1971-02-09
Anticipated expiration: 1988-02-09
Also published as: GB1172521A

Abstract

The disclosure relates to an elevator group supervisory control system in which bits of information, as to registered demands for service, position of the cars, and the degree of availability of the cars relative to the number of calls for service each is capable of answering without undue delay, are successively and repetitively scanned to control the respective movement of the cars.

Description

United States Patent [72] Inventor John Gingrich 3,443,668 5/1969 Hall et a1, 187/29 Toronto, Canada 2,827,981 3/1958 Eames et al.. 187/29 [21] Appl 592186 2,960,187 11/1960 Bruns et al... 187/29 [22] Filed No 4,1966 3,080,944 3/1963 Burgy et a1 187/29 [45] Patented Feb 9.197] 3,146,858 9/1964 Leroux et al..., 187/29 [73] Assignee Dover Corporation 3,315,765 4/1967 Dinning 1, 187/29 New York, 3,376,952 4/1968 lnuzuka et a1. 187/29 by mesne assignments 3,378,107 4/1968 Madison 187/29 [32] Priority Nov. 5,1965 3,379,284 4/1968 Yeastmg v 187/29 1 Great Britain Primary Examiner-Cris L. Rader [31] 47,065 Assistant ExaminerW. E. Duncanson,lr.

Artorney-Brumbaugh, Free, Graves & Donohue [54] ELEVATOR GROUP SUPERVISORY CONTROL SYSTEM 54 Claims, 50 Drawing Figs.

U-S. The disclosure relates to an elevator group Su. Cl B661) pervisory control system in which bits ofinformation, as to reofSearch V gi tered demands for ervice position of the cars and the degree of availability ofthe cars relative to the number of calls [56] References cued for service each is capable of answering without undue delay, UNITED STATES PATENTS are successively and repetitively scanned to control the 3,371,747 3/1968 Gingrich et a1. 187/29 respective movement ofthe cars.

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Claims

1. In an elevatoR system comprising a plurality of elevator cars serving a plurality of floors, car position means controlled by the positions of said cars, call registering means for registering calls for service by said cars for said floors, means for successively and repetitively scanning on a continuous basis said call registering means and said position means, controlling means responsive to said scanning means for controlling the movement of at least one of said cars dependent upon the relative positions of said calls to said cars, further comprising passenger responsive means for each car operable by the passengers in a car, direction means for each car controlled by the direction of movement for which a car is available to move, and means for indicating the degree of availability of each car relative to the number of calls for service it is capable of answering without undue delay controlled by said passenger responsive means and said direction means, and wherein said scanning means also scans said availability means and said controlling means controls the movement of said cars and selectively causes a car to answer hall calls dependent upon the condition of said availability means and the number and location of said hall calls in relation to said last-mentioned car and to said other cars.

2. For up-peak traffic when: a. there are less than a predetermined number of down hall calls, said last-mentioned number being no greater than the predetermined number is subparagraph 1a hereof; b. the total hall calls have a predetermined relation to the sum of the car availability numbers different from that for down-peak; and c. the ratio of the rate of car stops for car calls to the rate of car stops for down hall calls is at least equal to said predetermined value in subparagraph 1c hereof.

2. A system as set forth in claim 1 wherein said passenger responsive means comprises weighing means for weighing the load in a car and said availability indicating means has a first and a second condition when said load is respectively less than and at least a predetermined value.

2. means for selecting up trip cars in a predetermined order to be up-peak ''''special'''' and up-peak ''''normal'''' cars, and

2. in the down direction to said car, the up hall calls and availability numbers for cars above said car;

2. in a direction toward a car, the hall calls for service in a second direction and the availability numberS of cars in said away direction;

2. preferential service away from said main floor when: a. there are less than a predetermined number of down hall calls, said last-mentioned number being no greater than the predetermined number in subparagraph 1a hereof; b. the total hall calls have a predetermined relation to the sum of the car availability numbers different from that in subparagraph 1b. hereof; and c. said ratio of the rate of car stops for car calls to the rate of car stops for down hall calls is at least equal to said predetermined value set forth in paragraph 1c hereof.

2. said answering car is down-available and the scanning shows that there is a down hall call below said answering car and there is no other down-available car between said answering car and the last-mentioned call; or

2. availability number N-C: car available to move up or down and there is a number C of car calls registered for a floor or floors between the car and the floor of the next registered hall call in the direction in which the caR is available to move, wherein C is less than N and greater than O; and

3. availability number O and unavailable: a. car directionally available to move up or down but the number of registered car calls for a floor or floors between the car and the floor of the next registered hall call in the direction in which the car is available to move is equal to or greater than N; b. car unavailable, being out of service, or not available to move in the direction of a registered hall call or calls means for repetitively scanning on a continuous basis with respect to each car said hall call registering means and said availability means, and dispatching means responsive to said scanning means for directing an answering car to answer registered hall calls whenever:

3. the scanning shows, with respect to said answering car, that the number of scanned hall calls above said answering car has a predetermined relation to the sum of the availability numbers corresponding corresponding to the availability means theretofore scanned for other cars located above said answering car; or

3. in a direction away from a car, opposite to the direction away from the car set forth in (1), the hall calls for service in said second direction and the availability numbers of cars in said away direction first-mentioned in this subparagraph (3);

3. in the down direction below said car, the up hall calls and availability numbers for cars below said car;

3. means for preventing down bound, up-peak ''''special'''' cars from reversing direction before travelling to the main floor and from stopping to answer more than a predetermined number of down hall calls.

3. A system as set forth in claim 1 wherein said passenger responsive means comprises weighing means for weighing the load in a car and said availability indicating means has a first condition when said load is less than a first predetermined value, a second condition when said load is at least equal to said first predetermined value but less than a second predetermined value and a third condition when said load is at least equal to said second predetermined value.

4. A system as set forth in claim 2 wherein said passenger responsive means also comprises car call registering means in each said car, said means for registering calls include means at said floors for registering hall halls at said floors, and said availability indicating means also is controlled by said car call means and has conditions dependent upon the number of car calls registered in a car and their floor position relation to registered hall calls.

4. in a direction toward a car, opposite to the direction toward a car set forth in (2), the hall calls for service in said first direction and the availability numbers of cars in said last-mentioned away direction; said scanning means scanning the availability means and hall call registering means in the numerical order of the floors at which cars and hall calls are located whereby the status of hall calls and the cars available to answer such hall calls is substantially continuously indicated to the dispatching means for each operating car in the system.

4. in the up direction to said car, the down hall calls and availability numbers for cars below said car; whereby the hall call registering means and availability means are scanned in the order of their floor positions commencing at each car upwardly to the highest floor, downwardly to the lowest floor and then upwardly to said last-mentioned car.

4. the scanning shows, with respect to said answering car, that the number of scanned hall calls below said answering car has a predetermined relation to the sum of the availability numbers corresponding to the availability means theretofore scanned for other cars located below said answering car.

5. A system as set forth in claim 1 wherein said passenger responsive means comprises car call registering means in each said car and said availability indicating means is controlled by said car call means and has different conditions dependent upon the number of car calls registered in a car and their floor position relation to registered hall calls.

6. In an elevator system comprising a plurality of elevator cars serving a plurality of floors, hall call means at said floors for registering calls at said floors, car call means in said cars for registering calls for said floors, position means for each car controlled by the position of said car and direction means controlled by the direction of movement in which a car is available to move, the combination therewith of control means for controlling the movement of said cars, said control means availability means for each car controlled by said car call means and said direction means for indicating the availability of a car for movement in response to hall calls, said availability means having a plurality of conditions corresponding to the availability of its associated car and to availability numbers as follows:

7. A system as set forth in claim 6 wherein N is equal to 2, said first predetermined number is equal to 1, said second predetermined number is equal to 2 and said predetermined relation is a number of said hall calls greater than the sum of said availability numbers.

8. A system as set forth in claim 6 further comprising load means for each car responsive to the load therein and wherein said availability means is also controlled by said load means and said availability means also has said condition (3) and availability number zero when the load exceeds a predetermined value.

9. A system as set forth in claim 6 wherein said control means in the absence of car calls holds each car at the floor at which it stopped for its last call until the car is directed to answer a hall call by said dispatch means.

10. A system as set forth in claim 6 wherein one of said floors is a main floor and wherein said control means parks cars which are not answering hall or car calls at floors within predetermined groups of floors and parks at least one said car at a floor within a group of floors comprising a predetermined number of lower floors including said main floor, said last-mentioned number being less than about half the total number of floors.

11. A system as set forth in claim 6 wherein said dispatching means comprises a counter for each car, each such counter having means for adding an amount corresponding to said availability number and means for subtracting an amount corresponding to registered hall calls, and directing means responsive to said counter for directing a car to answer registered hall calls whenever the sum algebraic of said availability numbers and hall calls has a predetermined value and wherein said scanning means supplies information as to availability numbers and hall calls to each counter as follows:

12. A system as set forth in claim 11 wherein a car available for service is directed to answer a hall call for service whenever the sum of availability numbers and the hall calls is less than zero and wherein said scanning means supplies information as to availability numbers and hall calls to each counter as follows:

13. A system as set forth in claim 11 wherein said dispatching means further comprises modifying means for reducing the amount corresponding to an availability number added by a counter when the car corresponding to said last-mentioned counter has been directed to answer hall calls as a result of a hall call beyond another car available to move in the direction of said last-mentioned hall call.

14. A system as set forth in claim 6 wherein one of said floors is the main floor and further comprising means for detecting down-peak traffic conditions and peak traffic modifying means responsive thereto for modifying the operation of said system including means for selecting cars in a predetermined order of their arrival at the main floor to be ''''special'''' and ''''normal'''' cars, means for preventing the scanning means from supplying to the dispatching means for ''''normal'''' cars information as to condition of the availability means of upbound ''''special'''' cars, means for preventing upbound ''''special'''' cars from answering up hall calls above said main floor and means for preventing the scanning means from supplying to the dispatching means for upbound ''''special'''' cars information as to the condition of the availability means of ''''normal'''' cars above.

15. A system as set forth in claim 14 wherein said modifying means further comprises means for recording a predetermined number of down hall calls in the time order of registration and means for preventing the scanning means from supplying to the dispatching means for upbound ''''special'''' cars information as to down hall calls other than recorded down hall calls.

16. A system as set forth in claim 14 wherein said modifying means further comprises means for reducing the availability number of ''''special'''' cars.

17. A system as set forth in claim 14 further comprising means for detecting up-peak traffic conditions and wherein said modifying means is also responsive to said last-mentioned means for modifying the operation of said system and includes the following which operate when up-Peak traffic conditions are detected:

18. A system as set forth in claim 17 wherein said modifying means further comprises means operable when up-peak traffic conditions are detected, for causing up-peak ''''normal'''' cars to reverse direction at floors other than said main floor when there is no demand for service therefor in said direction and there is a demand for service in the opposite direction.

19. A system as set forth in claim 17 wherein said means for detecting peak traffic conditions comprises means for counting the number of down hall calls, means for counting hall calls, means for totaling the car availability numbers, means for comparing the number of hall calls with the sum of the car availability numbers, means for comparing the rate of car stops for car calls with the rate of car stops for down hall calls, and means responsive to said counting, totaling and comparing means for operating said modifying means as follows:

20. A system as set forth in claim 19 wherein said predetermined relation for down-peak traffic and said predetermined relation for up-peak traffic are respectively hall calls greater in number than and hall calls not greater in number than the sum of the car availability numbers.

21. In an elevator system having a plurality of elevator cars serving a plurality of floors, means at said floors for registering calls for service from said floors, means in said cars for registering calls for service to said floors and means for stopping said cars at floors for which calls are registered, the combination therewith of means responsive to said registering means and said stopping means for comparing the rate of car stops for car calls with the rate of car stops for down hall calls and controlling means responsive to said comparing means for controlling the movement of said cars.

22. A system as set forth in claim 21 further comprising counting means for counting hall calls and wherein said controlling means is also responsive to said counting means.

23. A system as set forth in claim 22 further comprising load means responsive to the load in said cars and availability means responsive to said load means and said car calls means and wherein said controlling means is also responsive to said availability means.

24. A system as set forth in claim 21 wherein one of said floors is a main floor and wherein said controlling means is conditioned to dispatch cars so as to provide preferential service away from said main floor when the ratio of the rate of car stops for car calls to the rate of car stops for down hall calls is at least equal to a predetermined value and said controlling means is conditioned to dispatch cars so as to provide preferential service toward said main floor when said ratio is less than said predetermined value.

25. A system as set forth in claim 24 further comprising means for counting hall calls including down hall calls, availability means for each of said cars, said availability means having different conditions dependent upon the directional availability of a car and the degree of availability of a car to answer hall calls, said conditions corresponding to predetermined availability numbers, totaling means controlled by said availability means for providing information as to the sum of the car availability numbers, and means for comparing the number of hall calls with the sum of the car availability numbers, and wherein said controlling means is conditioned not only by the ratio of the rate of car stops for car calls to the rate of car stops for down hall calls but also by said counting, totaling and comparing means so as to provide control of said cars as follows:

26. In an elevator system having a plurality of cars serving a plurality of floors, car call means in said cars operable by passengers therein for registering car calls for said floors, hall call registering means at said floors operable by intending passengers for registering hall calls, position means for each of said cars for providing information as to the positions of said cars and direction means for each of said cars for providing information as to the direction in which said cars are available to move, the combination therewith of means for controlling the movement and parking of said cars comprising availability means for each of said cars responsive to said car call means and said direction means for providing electrical signals corresponding to the directional and call availability of the corresponding car; counter means for each of said cars; scanning means; subtracting means responsive to said scanning means and to said hall call registering means for supplying subtract signals to the counter for each car for hall calls above each car and alternately for hall calls below each car; adding means responsive to said scanning means and to said availability means for supplying add signals to the counter for each car for cars above each car which are available to answer hall calls above each car and alternately for cars below each car which are available to answer hall calls below each car; reset means to reset said counter to a predetermined count condition between the supplying of subtract signals for hall calls above and the supplying of subtract signals of hall calls below to a counter; and control means responsive to the counter for each car for causing the car corresponding to a counter to answer hall calls when the count condition of the corresponding counter is other than said predetermined count condition just prior to resEtting of the counter for said last-mentioned car and said last-mentioned car is in-service and capable of answering hall calls.

27. A system as set forth in claim 26 wherein said scanning means comprises code means for providing electrical signals in binary digital code corresponding successively to each of said floors and the direction of scanning with respect to the numerical order of the floors and for providing, for each of the floors at which a car is positioned, electrical signals in binary digital code successively corresponding to each of said cars; further comprising position code means for each of said position means for providing electrical signals in binary digital code corresponding to the position of the corresponding car; further comprising parity means for each of said cars connected to said scanning means and said position code means for comparing the floor position signals of the corresponding car; wherein said control means comprises memory means for each of said cars, the memory means of each car being operable by said scanning means to cause said memory means to record a hall call at a floor at which the car is positioned; and said scanning means comprising operation means controlled by said parity means and controlling said availability means, said operation means being operable when said parity means indicates that there is a car at the floor position of the scan of said scanning means for causing the following operations as to each car at said last-mentioned floor: a. reading by said memory means of the output of the car''s corresponding counter; b. supplying of an add signal from the availability means, if the car is available, to at least all of said counters for cars other than at said last-mentioned floor; c. resetting of the car''s counter to zero.

28. In an elevator system having a plurality of cars serving a plurality of floors, car call means in said cars operable by passengers therein for registering car calls for said floors, hall call registering means at said floor operable by intending passengers for registering hall calls, position means for each of said cars for providing information as to the positions of said cars and directions means for each of said cars for providing information as to the direction in which said cars are available to move, the combination therewith of means for controlling the movement and parking of said cars comprising position code means for each of said position means for providing electrical signals in binary digital code corresponding to the position of the corresponding car; first scanning means for providing electrical signals in binary digital code successively corresponding to each of said floors and the direction of scanning with respect to the numerical order of the floors, said scanning means providing signals corresponding successively to the lowest and then higher floors and then providing signals corresponding successively to the highest and then lower floors; three memory means for each of said cars, a first memory means for hall calls above the cars, a second memory means for hall calls below the car and a third memory means for hall calls at the floor at which the corresponding car is located; a counter for each of said cars; parity means for each of said cars connected to said first scanning means and said position codes means for comparing the floor position signals of the scan with the floor position signals of the corresponding car; availability means for each of said cars controlled by said direction means and said car call means of the corresponding car for providing electrical signals corresponding to the directional and call availability of the corresponding car; second scanning means operable by said first scanning means each time the scan of said first scanning means steps to a different floor, said first scanning means also being controlled by said second scanning means and being stepped to a different floor after completion of a scan by said second scanning Means; hall call comparing means connected to said scanning means, said hall call registering means and said counters for providing a subtract signal to said counters when the first scanning means signals corresponds to the floor of the hall call registering means and a hall call is registered thereat; said second scanning means also controlling said third memory means of a car at said last-mentioned floor to cause said third memory means to record a hall call which may be registered at said last-mentioned floor and said second scanning means being operable when said parity indicates that there is a car at the floor position of the scan of said first scanning means for causing the following operations as to each car at said last-mentioned floor: a. reading by one of said first and second memory means, depending on the direction of movement of the scan of said first scanning means, of the output of the car''s corresponding counter; b. supplying of an add signal from the availability means, if the car is available to at least all of said counters for cars other than at said last-mentioned floor; c. resetting of the car''s counter to zero; and control means for each car responsive to said memories for causing the corresponding car to move or park dependent upon the conditions of said memory means and the availability of the car.

29. A system as set forth in claim 28 wherein said counters comprise means for preventing further addition when the count therein is zero.

30. A system as set forth in claim 28 wherein said second scanning means causes said operations in a predetermined sequence with respect to said cars when a plurality thereof are at the same floor other than a predetermined lower floor and when said first scanning means is scanning in the direction from lower to upper floors and causes said operations in a sequence which is reversed with respect to said predetermined sequence when a plurality of said cars are at the same floor other than said predetermined floor and said first scanning means is scanning in the direction from the upper to lower floors.

31. In an elevator system comprising a plurality of elevator cars serving a plurality of floors, car position means controlled in accordance with the positions of said cars, car direction means controlled in accordance with the direction in which a car is available to move, call registering means for registering calls for service by said cars for said floors, availability means controlled at least by said car direction means for providing information as to the availability of a car to answer registered calls, scanning means for successively and repetitively scanning the information provided by said call registering means, said position means and said availability means in a predetermined normal sequence for floors other than a predetermined floor, and controlling means responsive to said scanning means for controlling the movement of said cars dependent upon the number and relative position of said calls to said cars and the availability of cars to answer said calls, the combination therewith of selecting means for selecting a predetermined car at said predetermined floor and modifying means controlled by said selecting means upon selection of said predetermined car for modifying the operation of said scanning means in its scanning operation at said predetermined floor to provide a scanning sequence different from said normal sequence at said predetermined floor.

32. The combination as set forth in claim 31 wherein said scanning means, when modified in operation, scans with respect to the selected car first when scanning the information corresponding to the direction in which said selected car is set to move and scans with respect to the selected car last when scanning the information corresponding to the direction opposite to the direction in which said selected car is set to move.

33. The combination as set forth in claim 32 wherein said selecting means selects the car next to depart from said predetermined floor.

34. In an elevator system comprising a plurality of elevator cars serving a plurality of floors, car position means controlled in accordance with the positions of said cars, car direction means controlled in accordance with the direction in which a car is available to move, call registering means for registering calls for service by said cars for said floors, availability means controlled at least by said car direction means for providing information as to the availability of a car to answer registered calls, means for successively and repetitively scanning on a continuous basis the information provided by said call registering means, said position means and said availability means, controlling means responsive to said scanning means for controlling the movement of said cars dependent upon the number and relative positions of said calls to said cars and the availability of cars to answer said calls, and automatic car shutdown means for removing a car from service when the demands for service therefor fall below a predetermined level, the combination therewith of modifying means responsive to said shutdown means for preventing response of the controlling means corresponding to a car which has not been shut down to the scanning of information provided with respect to a car which has been shut down and for modifying the response of the controlling means corresponding to a shutdown car.

35. The combination as set forth in claim 34 wherein the controlling means of a shutdown car, when modified, responds to said scanning means when it is scanning information corresponding to cars which have not been shut down and responds differently in different scanning cycles to scanning information corresponding to shutdown cars.

36. The combination as set forth in claim 35 wherein during one scanning cycle, the controlling means of a shutdown car, when modified, responds to said scanning means when it is scanning information corresponding to shutdown cars located in a predetermined direction with respect to said shutdown car and does not respond to said scanning means when it is scanning information corresponding to shutdown cars located in a direction opposite to said predetermined direction with respect to said shutdown car.

37. A method of controlling a plurality of elevator cars to serve a plurality of floors, comprising continuously providing bits of information representing some or all of hall calls and car position and availability to answer the calls, repetitively scanning on a continuous basis said bits of information in a predetermined order and sufficiently rapidly that the cars do not effectively change their positions during each scan, and dispatching the cars in response to the scanned information from wherever the cars happen to be, in which the hall call information comprises, for each floor, information as to up and down hall calls registered from that floor, and the car position and availability information comprises, for each car, its availability to go up, its availability to go down, a car position corresponding to the nearest floor for which the car is available, and the degree of availability of the car.

38. A method as claimed in claim 37, in which the degree of availability of a car is the number of hall calls that the car is arbitrarily allowed to answer without requiring assistance from other cars.

39. A method as claimed in claim 38, in which car calls and car loading are used to reduce the degree of availability of the car.

40. A method as claimed in claim 37, in which the hall call information as to down hall calls at the various floors and the car position and availability as to cars available to go down are scanned in ascending order from the lowest to the highest floor, and then the hall call information as to cars available to go up are scanned in descending order.

41. A method as claimed in claim 40, in which for each floor the hall call information is scanned and then the car availability inFormation as to each car whose position is represented at that floor.

42. A method as claimed in claim 41, in which the information as to one car is scanned before the information as to another car whose position is represented at the same floor.

43. A method as claimed in claim 42, in which the predetermined order of scanning through the bits of information indicating car availability is altered during that portion of the descending scan when conditions at the main floor are being examined, so that the bits of information representing the availability of the next up car are scanned first, before the corresponding bits of information representing the availability of other cars, and in which the predetermined order of scanning through the bits of information indicating car availability is altered during that portion of the descending scan when conditions at the main floor are being examined, so that the bits of information representing the availability of the next up car are scanned last, after the corresponding bits of information representing the availability of other cars at the main floor have been scanned.

44. A method as claimed in claim 42, in which two consecutive bits of information are used to indicate a car''s degree of availability, one of them to indicate whether or not this car is available to answer two hall calls, and the other of them to indicate whether or not this car is available to answer one hall call, so that the combination of these consecutive bits can indicate that this car is available to answer none, one, two or three hall calls.

45. A method as claimed in claim 44, in which each car is normally available to answer two hall calls, but in which a car is available to answer only one hall call if loaded beyond a predetermined load, or if an intervening car call would require this car to make two stops before being able to answer the second of two existing hall calls, and in which a car becomes unavailable if loaded beyond a higher predetermined load, or if two intervening car calls would require this car to make two stops before answering an existing hall call.

46. A method as claimed in claim 45, in which it is determined whether there are hall calls above a car which the car should answer by resetting a counter at a point in the ascending scan during scanning of the conditions at the floor where the car is represented to be, by subtracting one each time a hall call is scanned, by adding two each time a car with an availability of two is scanned, by never allowing the accumulated count on the counter to be a positive number, and by reading the accumulated count on the counter at a point in the descending scan during scanning of the conditions at the floor where the car is represented to be, and in which a negative accumulated count is an indication that there are hall calls above, which this car should answer; and in which it is determined whether there are hall calls below a car which the car should answer by resetting a counter at a point in the descending scan during scanning of conditions at the floor where the car is represented to be, by subtracting one each time a hall call is scanned, by adding one each time a car with an availability of one is scanned, by adding two each time a car with an availability of two is scanned, by never allowing the accumulated count to be a positive number, and by reading the accumulated count on the counter at a point in the descending scan during scanning of the conditions at the floor where the car is represented to be, and in which a negative accumulated count is an indication that there are hall calls below, which this car should answer.

47. A method as claimed in claim 46, in which when the up direction of travel is established for a car, and when there are no hall calls below it which it should answer, its counter adds one, instead of two, each time a car above with an availability of two is seen during the scan; and when the down direction of travel is established for a car, and when There are no hall calls above it which it should answer, its counter adds one, instead of two, each time a car below with an availability of two is seen during the scan.

48. A method as claimed in claim 46, in which cars whose MG sets are running do not respond to the bits of information regarding the availability of cars whose MG sets are shut down automatically, and in which for each car whose MG set is automatically shut down it is determined when there are hall calls above it, which require it to start its MG set in order to answer some or all of these hall calls, be resetting a counter at a point in the descending scan during scanning of the conditions at the floor where the car is represented to be, by subtracting one each time a hall call is scanned, by adding one each time a car with an availability of one, and whose MG set is running, is scanned, by adding two each time a car with an availability of two is scanned, whose MG set is running, by allowing the accumulated count to be a positive number as well as a negative number, by continuing this counting until a point in the ascending scan is reached where the conditions at the floor where the car is represented to be is being scanned, by resetting the counter at this point only if the accumulated count on the counter is negative, by continuing to subtract one each time a hall call is scanned, by adding one each time a car with an availability of one is scanned, provided that the accumulated count is negative or that the car has its MG set running, by adding two each time a car with an availability of two is scanned, provided that the accumulated count is negative or that the car has its MG set running, and by not allowing such addition of two to take the accumulated count from a negative number to beyond zero except for a car whose MG set is running, and by reading the accumulated count on the counter at a point in the descending scan when conditions at the floor where the car is represented to be are being scanned, and in which a negative accumulated count is an indication that this car should start its MG set, and go up to answer hall calls above; and in which for each car whose MG set is automatically shut down it is determined when there are hall calls below it, which require it to start its MG set in order to answer some or all of these hall calls, by resetting a counter at a point in the ascending scan during scanning of the conditions at the floor where the car is represented to be, by subtracting one each time a hall call is scanned, by adding one each time a car with an availability of one, and whose MG set is running, is scanned, by adding two each time a car with an availability of two is scanned, whose MG set is running, by allowing the accumulated count to be a positive number as well as a negative number, by continuing this counting until a point in the descending scan reached where the conditions at the floor where the car is represented to be are being scanned, by resetting the counter at this point only if the accumulated count on the counter is negative, by continuing to subtract one each time a hall call is scanned, by adding one each time a car with an availability of one is scanned, provided that the accumulated count is negative or that the car has its MG set running, by adding two each time a car with an availability of two is scanned, provided that the accumulated count is negative or that the car has its MG set running, and by not allowing each addition of two to take the accumulated count from a negative number to beyond zero except for a car whose MG set is running, and by reading the accumulated count on the counter at a point in the ascending scan when conditions at the floor where the car is represented to be are being scanned, and in which a negative accumulated count is an indication that this car should start its MG set, and go down to answer hall calls below.

49. A method as claimed in claim 37, in which the floors are divided intO at least four groups of floors of which the lowest group contains the main floor, and in which cars are distributed throughout the building, when not otherwise required for the answering of car or hall calls, such that, as long as a predetermined number of cars more than one are available, in the absence of cars in the lowest group of floors the lowest car is brought down to the main floor, in the absence of cars in the upper two groups of floors the highest car travels up until it is at the lowest floor of the upper group of floors, in the absence of cars in any intermediate two immediately adjacent groups of floors the lowest car in a group of floors above the two adjacent groups, provided that there are two or more such cars there, travels down until it is at the top floor of the lower of these two intermediate adjacent groups of floors, or, if there are less than two cars in the group of floors, above the two adjacent groups, and there are no cars in the two intermediate adjacent groups of floors, the highest car in a group of floors below the two adjacent groups travels up until it is at the bottom floor of the higher of these two intermediate adjacent groups of floors, provided that there are at least two cars in the lowest group of floors.

50. A method as claimed in claim 37, in which the floors are divided into four groups of floors of which the lowest group contains the main floor, and in which cars whose MG sets are running are distributed throughout the building, when not otherwise required for the answering of car or hall calls, such that, as long as two or more cars have their MG sets running, in the absence of cars with MG sets running in the lowest group of floors the lowest car with MG set running is brought down to the main floor, in the absence of cars with MG sets running in the upper two groups of floors the highest car with MG set running travels up until it is at the lowest floor of the upper group of floors, in the absence of cars with MG sets running in the middle two groups of floors the lowest car with MG set running in the upper group of floors, provided that there are two or more such cars there, travels down until it is at the top floor of the lower of these two middle groups of floors, or, if there are less than two cars with MG sets running in the upper group of floors, and there are no cars with MG sets running in the middle two groups of floors, the highest car with MG set running in the lowest group of floors travels up until it is at the bottom floor of the higher of these two middle groups of floors, provided that there are at least two cars with MG sets running in the lowest group of floors.

51. A method as claimed in claim 37, in which the order of registration of down hall calls, for floors above the main floor, is continuously recorded, and in which, during down-peak, one group of cars answers long-wait down hall calls, and another group of cars answers other calls including up hall calls.

52. A method as claimed in claim 51, in which, upon arrival at the main floor during down peak, cars are allocated to said one group and remain in said one group only until they commence their next down trip, cars not so allocated and all cars in their down trip belonging to said other group.

53. A method as claimed in claim 52, in which the allocation of cars to said one group or to said other group upon arrival at the main floor follows a predetermined sequence independent of whether a car has previously been allocated to said one group.

54. A method as claimed in claim 53, in which the number of calls treated as long-wait calls equals the number of cars allocated to said one group.