Elevator – industrial lift truck – or stationary lift for vehicle – With call registration means – Shared by plural load supports
Reexamination Certificate
2000-06-23
2001-09-25
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
With call registration means
Shared by plural load supports
C187S902000, C706S910000
Reexamination Certificate
active
06293368
ABSTRACT:
The present invention relates to a genetic procedure for the control of an elevator group.
When a passenger wants to have a ride in an elevator, he/she calls an elevator by pressing a landing call button on the floor in question. The elevator control system receives the call and tries to figure out, which one of the elevators in the elevator bank can serve the call best. This activity is termed call allocation. The problem to be solved by call allocation is to establish which one of the elevators is to serve each call so as to minimise a preselected cost function.
Traditionally, to establish which one of the elevators will be suited to serve a call, the reasoning is performed individually in each case by using complex condition structures. Since the elevator group has a complex variety of possible states, the condition structures will also be complex and they often have gaps left in them. This leads to situations in which the control system does _not function in the best possible way. Furthermore, it is difficult to take the entire elevator group into account as a whole.
Finnish patent application FI 951925 presents a procedure for the allocation of landing calls in an elevator group, in which some of the problems described above have been eliminated. This procedure is based on forming a plurality of allocation options, each of which comprises a call data item and an elevator data item for each active landing call, and these data together define the elevator to serve each landing call. After this, the value of a cost function is computed for each allocation option and one or more of the allocation options are repeatedly altered with respect to at least one of the data items comprised in it, whereupon the values of the cost functions of the new allocation options thus obtained are computed. Based on the values of the cost functions, the best allocation option is selected and active elevator calls are allocated accordingly to the elevators in the elevator group.
The solution presented in the above application substantially reduces the required calculation work as compared with having to. calculate all possible route alternatives. In this procedure, which is based on a genetic algorithm, the elevator group is treated as a whole, so the cost function is optimised at the group level. The optimisation process need not be concerned with individual situations and ways of coping with them. By modifying the cost function, desired operation can be achieved. It is possible to optimise e.g. passenger waiting time, call time, number of starts, travelling time, energy consumption, rope wear, operation of an individual elevator if. using a given elevator is expensive, uniform use of the elevators, etc., or a desired combination of these.
In order to further increase the efficiency and capacity of elevator groups, elevator systems have been developed in which two or even three cars placed on top of each other travel in the same elevator shaft. Such elevators are called double-deck or triple-deck elevators.
In prior art, if landing calls were only served by double-deck elevators, then after the decision regarding the selection of an elevator it would be necessary to make a second decision about which one of the two decks is to serve the landing call. For the latter decision, it is necessary to have rules which must take the whole elevator group into account and which must be comprehensive if the control system is to find an optimal solution in respect of a desired, alterable cost function. In addition, the selection rules must be applicable for use directly in any elevator group configuration and in any traffic situation.
The object of the present invention is to eliminate the drawbacks described above. A specific object of the present invention is to disclose a new type of procedure that enables allocation of calls given via landing call devices of elevators comprised in a multi-deck elevator group. In this context, multi-deck elevator group means an elevator group that comprises at least one multi-deck elevator, possibly several single-deck, double-deck and triple-deck elevators in the same elevator bank.
The genetic procedure of the invention for the control of a multi-deck elevator group is based on the insight that although the same elevator may comprise several cars, these can initially be regarded as separate cars, and a suitable car is allocated to serve each landing call. This makes it possible to avoid making decisions at two levels as mentioned above. However, as the cars in the same elevator are not independent of each other, the interaction between them will be taken into account when. a car selection alternative is input to a multi-deck elevator model in which the cars are associated with the elevators to which they belong.
In the genetic procedure of the invention, a multi-deck elevator model is formed in which the limitations of and rules of behaviour for each elevator in the multi-deck elevator group and each car of each elevator are defined. After this, a number of allocation options, i.e. chromosomes are formed, each of which contains a car data item and an elevator direction data item for each active landing call, and these data, i.e. genes, together define a car to serve the landing call as well as the collective control direction for the elevator. For the chromosomes thus generated, fitness function values are determined, and one or more of the chromosomes are selected, which are then altered in. respect of at least one gene. For the new chromosomes thus obtained, fitness function values are determined, and the process of forming chromosome mutations and selecting chromosomes and determining fitness functions is continued until a termination criterion is met. After this, based on the fitness function values, the most suitable chromosome is selected and the calls are allocated to the elevators and cars in the elevator group in accordance with this solution.
Thus, in multi-deck group control according to the invention, decision-making is based on route optimisation effected using a genetic algorithm. In the route optimisation, each landing call is served. A problem in the route optimsation is exponential increase of the number of alternative solutions as the number of landing calls increases. The multi-deck system further increases the number of alternative solutions if the elevators are treated as separate cars. For this reason, the number of alternatives and the computation power needed soon become too large even in small multi-deck elevator groups. A genetic algorithm substantially reduces the computation work needed, because it can select a solution without systematically working through all the alternative solutions. In addition, it is of a parallel structure by nature, so the computation work can be divided among several processors.
The genetic algorithm of the invention operates with a set of alternative solutions whose ability to solve the problem is developed until the termination criterion for the optimisation is met. The fitness of each alternative solution to become a control decision depends on the value it is assigned after it has been processed in the elevator model and its cost has been calculated using a desired cost function. The termination criterion may consist of e.g. a predetermined fitness function value obtained, a number of generations, an amount of processing time or a sufficient homogeneity of the population.
Thus, in the optimisation method of the invention, the first task is to define a search expanse in which the extent of the problem is described and the limitations for optimisation are set. The resources, the limlitations and the prevailing traffic situation together form an elevator model or an operating environment in which the group controller must perform its function in the best manner possible in accordance with the task assigned to it. At any given point of time, the operating environment may thus comprise e.g. the number of elevators together with car sizes and degrees of occupancy, factors relating to the drives such as travelling ti
Tyni Tapio
Ylinen Jari
Kone Corporation
Salata Jonathan
LandOfFree
Genetic procedure for multi-deck elevator call allocation does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Genetic procedure for multi-deck elevator call allocation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Genetic procedure for multi-deck elevator call allocation will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2455650