Procedure and apparatus for the control of elevator doors

Abstract: The invention relates to a procedure and an apparatus for controlling the doors (2) of an elevator. According to the invention, a sensor (4) detects the presence of elevator passengers in the lobby and a detecting device (6,8,9) observes the occurrences of passengers moving from the elevator car (3) into the lobby and from the lobby into the elevator car (3), while a motion detector observes the movements of the passengers in the car. The passenger data (10,11) thus obtained are utilized in the process of making a decision regarding the closing of the doors.

Description: The present invention relates to a procedure according to the introductory part of claim 1 and an apparatus according to the introductory part of claim 7 for the control of elevator doors. The function of an elevator is to provide a certain transport capacity for the transportation of passengers between the floors of a building. The capacity should be as high as possible. It depends on the number, dimensions and travelling speed of the elevator cars. For the transport capacity to be efficiently exploited, the time the elevator spends standing at a floor should be as short as possible, i.e. only as long as is necessary to allow the passengers to leave the car and new passengers to enter. All time in excess of this is dead time, during which the elevator cannot move and no passengers are entering or leaving the car. The operation of the door control system is of great importance in the utilization of the transport capacity, because the better the door control procedure, the sooner the doors can be closed after the last passenger has entered/left the car and the more effectively is the transport capacity of the elevator utilized. On the other hand, if the doors are closed too soon, a passenger may be caught between the doors. In principle, this involves no danger, because the safety circuits will reopen the doors. However, this is an unpleasant experience for the passenger, and it also means wasting time as it disturbs the normal movement of passengers and reopening the door takes its own time. In a previously known procedure, the movement of a passenger into or out of an elevator car is detected by means of a light beam passing between the door posts. When the passage of a passenger into or out of the car is detected from an interrupted light beam, the door is kept open for a certain delay in case another passenger should follow. This system has obvious drawbacks: the delay is dead time and should therefore be minimized. However, the delay cannot be shortened without limit because the behaviour of the door would then become aggressive as the door would tend to close too soon, jamming the passenger in the doorway. The method is a mixture of a real time procedure and a statistical one: the passengers are observed in real time but the action (delay) triggered by them contains an implicit idea of normal passage of passengers and a normal preset mean distance between them during the movement. Publication EP A2 452 130 presents a procedure whereby the door-open time is estimated on the basis of history data. The operation is based on counting and keeping floor-specific statistics of the numbers of passengers entering and leaving the elevator car. The history data are used for the determination of the door-open time for each hour of the day. As the procedure depends heavily on statistics, it cannot take the momentary situation prevailing around the door into account. The object of the present invention is to create a new procedure for the control of elevator doors which enables the transport capacity of the elevator to be utilized as efficiently as possible while minimizing the delays in the closing of the doors. To achieve this, the invention is characterized by the features presented in claims 1 and 7. The other preferred embodiments of the invention are characterized by the features of the dependent claims. The invention provides a truthful real-time picture of the situation regarding the loading and unloading of the elevator car, enabling the system to close the doors as soon as it perceives that all those who wanted to enter/leave the car have done so. According to the invention, the presence of passengers in the lobby and their passage from the lobby into the car and vice versa as well as their movements in the car are continuously observed and this information is used as a basis for real-time data about the movements of passengers in the doorway and in its vicinity. In the procedure of the invention, there is no use for the concept of 'door-open time' and no open time need be determined in the control of the doors, because the doors are closed as soon as the passenger situation on the floor in question and in the elevator car allows it. In the following, the invention is described in detail by the aid of an example by referring to the attached drawings, in which Fig. 1 presents a diagram of the apparatus of the invention. Fig. 2 illustrates the measurement of the load signal. Fig. 3 presents a diagram of the states in the decision-making process of the procedure of the invention. Figure 1 presents a perspective view of an elevator car 1 and related equipment essential to the operation of the invention, mounted in the car or connected to it via signal conductors. The elevator car 1 is moved along an elevator shaft by means of a rope 23. Fitted in the front wall of the elevator car is a sliding door 2, through which the passengers move from the car into the elevator lobby when the elevator has stopped at a floor. The door is provided with a conventional light cell 24 and safety edges, which, upon detecting an obstacle in the path of the door, produce an instruction to open the door. The elevator car is provided with a lobby detector 4, which is mounted above the door in the middle of the doorway and recognizes a passenger waiting for the elevator. The lobby detector 4 may be implemented e.g. in the manner known from patent FI C 70651 (Int. Cl. G 06 K 9/28) and acts as a sensor indicating the presence of passengers. It detects any passengers present within the area 5 in front of the door and produces a corresponding signal containing first passenger data, which is passed via a signal connection 11 to a door control computer 21. Placed under the car is a load-weighing device 6 which measures the magnitude and variations of the load. The load weighing device consists of a scale placed under the floor of the car and measuring the car load only, or a sensor placed in the car frame and measuring the weight of the whole car. Alternatively, the scale can also be placed elsewhere in the car frame or in the supporting structure, not necessarily under the car. These various weighing devices are known in themselves in elevator technology and need not be discussed further. The signal obtained from the load weighing device shows stepwise changes caused by passengers entering or leaving the car. Similarly, it shows the changes resulting from the steps taken by passengers in the car. The solution of the invention is designed to recognize these changes. Since the car hangs suspended from ropes in the shaft, its mass together with the elasticity of the ropes constitutes a mechanical resonance circuit. The change in resonance circuit energy resulting from the movements of the passengers excites the system to vibrate at its own resonant frequency. These vibrations are also transmitted to the weight signal, making it fairly difficult to distinguish the desired events by conventional algorithmic methods. For this reason, the signal obtained from the load weighing device is passed via a signal conductor 7 to a filtering and processing device 8 performing a preliminary processing, and further to a neural network 9. In addition to filtering the signal, the filtering and processing device 8 shifts the reference level of the signal according to the prevailing situation. Figure 2 presents an example of the load weight signal and of how it is processed to enable the desired information to be obtained through the neural network 9. From the load weight signal, a portion of a length equal to time t 1 is observed as a separate "window", from which 8 signal values are taken at equal intervals. The signal is so scaled that the first value of each window occurs at the middle of the window, so that the window has room for the changes resulting from the movement of a passenger. The signal values inside the window under consideration are applied to the inputs of the neural network 9. During the teaching of the network, the interconnections between the neurons of the network are assigned values such that certain input signals correspond to a given output signal 10 representing passenger movement: passenger in, passenger out, or passenger moving inside car. Thus, the network output signal provides real-time second and third data representing the movement of passengers between the car and the elevator lobby, and a fourth data representing the movement of a passenger inside the car. The output signal of the neural network is taken via connections 10 into the door control computer 21, where it is used in the formation of the decision regarding the closing of the door. In the above, the detector indicating the passage of a passenger into/out of the car and the motion detector substantially consist of the same apparatus. However, these devices can also be implemented separately. According to an embodiment of the invention, the occurrences of a passenger moving between the car and the lobby are detected by means of a weighing device placed on the landing in front of the elevator door. By suitably analyzing the signal obtained from this weigher, the occurrences of a passenger moving in or out can be determined. The elevator car is provided with call buttons 12, by means of which the passenger selects his/her target floor. The call signal is passed via connection 13 to the elevator control computer 16, whose outputs inform the door control computer 21 via connections 18 and 19 as to whether the elevator is at the floor in question or whether a car call to that floor has been issued. Similarly, by pressing the call button 14 at the landing, a passenger waiting for an elevator gives a landing call, which is passed via conductor 15 to the group control computer 17, which informs the door control computer 21 via connection 20 about the landing call issued from that floor. The door control computer 21 forms a decision and transmits it via its output 22 to the door actuator. The elevator control system has been described above on a general level. Many details and practical implementations may vary greatly depending on the application, without affecting the present invention. The diagram of elevator states presented in figure 3 shows how the door control computer 21 makes a decision on the basis of the information supplied to it. Under the control of the elevator control system, the elevator arrives at a landing and the doors are opened. The elevator is now in a starting situation as represented by block 41. If a car call is in effect, the system proceeds to the unload state, block 42, as indicated by arrow 45. If no car call is present, the system proceeds via arrow 46 to the load state, block 43. It is assumed that the passengers leaving the car come out first and the new passengers enter after that, although this is irrelevant to the invention. In block 42, the car call is considered via loop 51 as reset when one passenger moves out of the car, this information being obtained from the output 10 of the neural network. If no movement is detected in the car and no landing call is in effect, the system proceeds via arrow 52 to block 44, i.e. decides to close the door. In addition, the system employs a time control procedure according to which it decides to close the door if no movement occurs in the car. Typically, such a situation arises when a passenger has pressed the wrong button in the car. From the load state 43 the system proceeds to the unload state 42 when a passenger steps out (arrow 55) of the car, and the possible car call is reset at the same time. A passenger entering the car resets the landing call, arrow 56, and if there are no passengers waiting in the lobby and no car call to the floor is in effect, arrow 57, the system decides to close the door, block 44. The time control procedure closes the door if no passenger is detected in the lobby within a certain time (arrows 58 and 59), e.g. because the person who pressed the landing call button has left the lobby. As mentioned in connection with figure 1, the door system of an elevator also includes a light cell and safety edges, which prevent the closing of the door when a passenger is in the doorway. Moreover, the system is provided with manual door opening and closing buttons. However, these devices produce high-priority signals that bypass the decisions of the system of the present invention and they can be connected to the logic circuitry after the system of the invention, e.g. near the door actuator. In the above, the invention has been described in reference to one of its preferred embodiments. However, the presentation is not to be regarded as constituting a limitation of the sphere of protection of the invention, but the embodiments of the invention may vary within the limits defined by the following claims.

Claims: Procedure for the control of elevator doors (2), whereby the presence of elevator passengers in the lobby is observed by means of a sensor (4) to produce a first passenger data signal (11), characterized in that the occurrences of passengers moving from the elevator car (3) into the lobby and from the lobby into the elevator car (3) are detected to produce a second and a third passenger data signal, respectively, and that movement of the passengers within the car is detected to produce a fourth passenger data signal, and that the passenger data (10,11) thus produced are utilized in determining when to close the doors. Procedure according to claim 1, characterized in that the occurrences of passengers moving from the car (3) into the lobby and from the lobby into the car (3) are determined from the load signal produced by a weighing device (6) measuring the load of the elevator. Procedure according to claim 1 or 2, characterized in that movement of the passengers in the car (3) is determined from the load signal produced by a weighing device (6) measuring the load of the elevator. Procedure according to claim 2 or 3, characterized in that the load data is analyzed by means of a neural network (9) whose output (10) provides real-time information about the movements of passengers within the car (3) and between the car and the lobby. Procedure according to claim 4, characterized in that the neural network (9) is taught the strengths of the connections between the neurons of the neural network so that each output data signal (10) of the neural network corresponds to a relevant input data signal. Procedure according to claim 1-5, characterized in that the decision when to close of the doors is made by utilizing information about car calls and/or landing calls relating to the floor of stopping. Apparatus for the control of elevator doors (2), comprising a sensor (4) designed to observe passengers present in the lobby, characterized in that the apparatus comprises a detecting device (6,8,9) used to detect respectively the occurrences of a passenger moving from the car (3) into the lobby and the occurences of a passenger moving from the lobby into the car, a motion detector (6,8,9) designed to detect movement of the passengers in the car, and means (10,11) for transmitting the information obtained from the sensor (4), detecting device and motion detector (6,8,9) to a door control computer (21) so as to determine when to close the door (2). Apparatus according to claim 7, characterized in that the detecting device (6,8,9) consists of a weighing device (6) of the elevator and a neural network (9) connected to the weighing device, said neural network analyzing the measurement data produced by the weighing device (6) to determine the real-time movements of passengers. Apparatus according to claim 7, characterized in that the detecting device consists of a weighing apparatus placed on the landing floor in front of the elevator doorway and a neural network (9) connected to the weighing apparatus, said neural network being used to deduce from the measurement data real-time information regarding passage of passengers between the car (3) and the lobby. Apparatus according to claim 7 - 9, characterized in that the motion detector (6,8,9) consists of a weighing device (6) measuring the load of the elevator and a neural network (9) connected to the weighing device, said neural network deducing from the weight data the movements of passengers in the car (3).

Inventors: TYNI TAPIO, TYNI, TAPIO
Applicants: KONE ELEVATOR GMBH
Application year: 1993
Main classification: B66B13
IPC codes: B66B3, B66B13, B66B1