Patent Application
20070045052
This invention generally relates to elevator systems. More particularly, this invention relates to assigning elevator cars to respond to passenger requests.
Elevator systems have been in use for many years. Traditional elevator systems include hall call buttons located near an entrance to an elevator shaft. Passengers use hall call buttons to indicate a desire to travel up or down from their current location. Upon entering the elevator car, the passenger utilizes a car operating panel to indicate the destination they intend to reach. The elevator car then travels to the appropriate destination where the passenger can exit the elevator.
Various control schemes have been proposed for assigning elevator cars to respond to passenger requests. In some buildings, it is desirable to use particular control algorithms to manage elevator traffic to handle particular traffic conditions. For example, some elevator systems are designed to assign elevator cars in a way that minimizes wait time for passengers at a lobby level, for example.
One known dispatching technique includes using fuzzy logic for assigning elevator cars to respond to passenger requests placed using hall call buttons. U.S. Pat. No. 5,668,356 describes such an arrangement. For such systems, the elevator dispatcher does not know the destination of passengers until the passengers board the elevator and enter their destinations with the car operating panel buttons. Such systems are not able to discern how many passengers are waiting behind a hall call or how many passengers are associated with each destination call or car call because the hall call buttons and the car operating panel buttons do not provide an indication of how many individuals correspond to each request. For example, four people may enter an elevator all intending to travel to the same destination but the destination button on the car operating panel is only pressed once, typically.
Although it has been possible to estimate how many passengers were waiting behind a hall call based on past observed traffic patterns or sensors located at a lobby level, for example, those approaches have been adopted in a way that has only limited usefulness within elevator dispatching control schemes. For example, hardware crowd sensors typically add cost and there are challenges associated with installing and locating them in a manner that makes it acceptable to building owners and architects, for example. Further, the number of floors at which such sensors can be installed for a group of elevators is limited and can only provide limited information.
Another elevator car dispatching technique is associated with the so-called destination entry systems. A typical destination entry system includes a device that allows a passenger to request elevator service and to indicate the passenger's intended destination before the passenger enters an elevator car. Such systems provide an advantage in that an elevator car dispatching algorithm can take into account the passenger's intended destination as part of the car assignment technique. Various proposals in this regard have been made.
Those skilled in the art are always striving to make improvements. It would be useful to enhance the capability of known elevator car assignment techniques to improve passenger service. This invention addresses that need.
An exemplary disclosed method of controlling an elevator system includes assigning an elevator car to respond to a passenger request based upon the desired destination of the passenger and a fuzzy logic car assignment algorithm. In a disclosed example the passenger request indicates the passenger's desired destination before the passenger enters an elevator car. One example includes determining whether a candidate elevator car is currently assigned to travel to the desired destination and using one of a plurality of fuzzy logic car assignment algorithms based upon that determination.
One disclosed example includes determining whether a candidate elevator car is assigned to travel to a source landing of the passenger request from which the passenger will board an elevator car to be carried to the desired destination. One example includes determining a type of call that the candidate elevator car is assigned to respond to when traveling to the source landing. A corresponding one of a plurality of fuzzy logic algorithms is selected responsive to the determined type of call.
A disclosed example includes providing more than one fuzzy logic algorithm depending on the relationship between an elevator car's current assignments and the passenger request including the source landing of the request and the passenger's desired destination.
One disclosed example includes determining whether a candidate elevator car will have enough capacity to receive the passenger at the source landing. One example includes using passenger destination information to determine an estimate of how many passengers will be on the elevator car or will board the elevator car at the source landing as part of determining whether a candidate elevator car has enough capacity to service the passenger request.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
Disclosed example embodiments of this invention provide elevator car dispatching techniques that include using passenger destination information and a fuzzy logic car assignment algorithm.
A single controller 36 is schematically shown in the example of
In one example, the controller 36 uses various dispatching algorithms for assigning elevator cars to desired passenger destinations. One example includes using fuzzy logic assignment algorithms based upon decision-making techniques similar to those described in U.S. Pat. No. 5,668,356. The teachings of that document are incorporated into this description by reference.
One example includes selecting one of a plurality of fuzzy logic algorithms for determining whether a particular one of the elevator cars should be assigned to service a particular passenger service request. In one example, the selection of the fuzzy logic algorithm depends on a relationship between the passenger request and the current assignments for a candidate elevator car. One example includes using the passenger's desired destination, which is known before the passenger enters an elevator car, as a factor in deciding which fuzzy logic algorithm to use before deciding whether to assign a particular elevator car to service the passenger's request. Another factor used in a disclosed example is the source landing of the passenger request from which the passenger will board an elevator car to be carried to the desired destination.
When the determinations at 42 and 44 are both positive, the example of
Assuming that the candidate elevator car does not have a hall call at the passenger source landing, a determination is made at 52 whether the elevator car has a car call at the passenger source landing. A car call in this context is used to refer to an assignment for that elevator car to travel to the source landing of the passenger request under consideration for purposes of dropping off a passenger, who is already on the elevator car, at the source landing. If so, a determination is made at 54 whether that elevator car has a call at the passenger's desired destination. This is the same determination made at 44, for example.
When the determinations at 52 and 54 in the example of
For situations where a candidate elevator car does not have a hall call or a car call at the source landing of the passenger request, a determination is made at 60 whether the candidate elevator car has a call at the passenger's intended destination. In other words, a determination is made at 60 whether the passenger's desired destination indicated in the request under consideration is the same as a destination to which that the elevator car is already assigned to travel. If so, a coincident destination call fuzzy logic algorithm is used at 62 for determining whether to assign that car to service that passenger request.
In the example of
As can be appreciated from the example of
The fuzzy logic algorithms mentioned in this description can take a variety of forms. Those skilled in the art who have the benefit of this description and information regarding known fuzzy logic car assignment algorithms will be able to develop an algorithm that meets the particular needs of an elevator system for a given situation.
Another feature of an example embodiment is determining whether a candidate elevator car will have enough capacity to receive a passenger when it arrives at the source landing of the passenger's request, allows any existing passengers to exit the car and boards all other passengers assigned to that car from that source landing. One example approach is summarized in the flowchart 70 of
At 82, a determination is made whether the car has been assigned to pick up any passengers at a particular floor. In the event that such an assignment has been made, the number of estimated passengers in the car is increased at 84 according to the number of requests made and assigned to that car. The next floor along the direction of travel toward the source landing is selected at 86 and the process between the steps 76 through 84 repeats as necessary.
Once all appropriate floors have been considered, the estimated number of passengers in the car is compared to the elevator car capacity at 88. In the event that there is enough capacity remaining, that car is considered for possible assignment to service the passenger request at 90. If the estimated number of passengers in that car is at least equal to the car's capacity, that car is not considered for assignment as indicated at 92.
One example includes considering how many passengers have already been assigned to a particular car that will board the car at the same source landing as the passenger request under consideration. This allows for determining whether the elevator will become overcrowded at the source landing before a particular passenger may have an opportunity to board that elevator car.
At the same time, considering what passengers have been assigned to an elevator car allows for one example controller 36 to give a higher priority to one elevator car compared to another. For example, where two elevator cars will both arrive at a source landing at approximately the same time, it is desirable to assign a passenger to an elevator car that already has passengers boarding that elevator car from the source landing. This creates a more natural passenger flow for the individuals boarding an elevator car compared to, for example, assigning several individuals to one elevator car and one individual to another elevator car that will arrive at the source landing and currently is assigned only to drop off individuals at that source landing. People tend to follow other people onto elevator cars rather than boarding a car by themself. One example controller is designed to prioritize elevator car assignments accordingly.
The disclosed example approaches take advantage of information such as that available from destination entry systems. By utilizing a passenger's desired destination in combination with a fuzzy logic assignment algorithm enhances elevator system performance and provides better passenger service. For example, identifying coincident stops for the elevator car (i.e., coincident destinations for assigned passengers), the number of stops an elevator must make to service passengers can be reduced. Further, the disclosed example considers the type of coincident stop for selecting an appropriate fuzzy logic algorithm to apply to achieve the best possible elevator service for a passenger request. The disclosed example effectively replaces the single coincident call fuzzy rule that is used in known elevator systems with a plurality of fuzzy logic algorithms that can be selected based upon the relationship between a passenger request and the current assignments for an elevator car.
Another advantage of the disclosed example is that it estimates whether an elevator car will have enough capacity to receive a particular passenger. This reduces the chance that an elevator car will be too full to serve a request. Therefore, the disclosed example avoids the difficulties and drawbacks associated with arrangements that require a passenger or several passengers to reenter their service request after a car that had been previously assigned to them arrives at the source landing.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.
