The Value of Contiguous Grouping within Destination Dispatching 2

The Value of Contiguous Grouping within Destination Dispatching 2

Traditional elevator dispatching
Traditional elevator systems work by allowing a prospective elevator passenger to pres a button in the hall that signals to the elevator system that the passenger wants to go up or down in the building. Individuals arriving with or after the first passenger who want to travel in the same direction do not need to press the hall button again. The dispatcher assigns an elevator to go to the floor at which the signal was registered and must do so without knowing the passenger’s exact destination.
When the assigned elevator arrives at the floor and opens its doors it also indicates in which direction it will be traveling. All passengers in the hall who want to travel in the indicated direction enter the elevator car. Once the passengers enter the elevator car they indicate their destination floor to the elevator system by pressing a button in the car operating panel located inside the car. If the desired destination has already been registered by someone else, the appropriate button will be lit and there is no need for the newly entered passenger to register it again.
In the traditional approach, the elevator system does not know passengers’ destinations until after the passengers enter the car, and the elevator car must serve all of the destinations entered via its car operating panel during the next trip.
Destination dispatching
Destination dispatching elevator systems work by allowing a prospective elevator passenger to press a button on a destination entry device (e.g. a keypad or a touchscreen) in the hall that tells the elevator system the passenger’s exact destination. By pressing the “7” button, for example, the passenger tells the system that he or she wants to go to floor 7. Unlike the traditional interface, each person arriving at the elevators must enter their own service request via the destination entry device. The destination dispatcher evaluates the state of the system and determines which car should answer the service request; the selected car is displayed on the destination entry device so that the passenger knows which elevator will serve him ro her. Often the passenger will move to stand in front of the assigned car so that he can board promptly when the car arrives.
Use of destination dispatching in an elevator system means that not all waiting passengers in an elevator lobby are waiting for the same car. While one passenger may have been told to use car A, another passenger may have been instructed to wait for car C. Since the elevator system already knows which destinations are assigned to each elevator, passengers do not need to enter their destination once inside the elevator car.
Destination dispatching can offer improved performance in many building and traffic scenarios as compared to traditional dispatching. Improvements are generally due to the dispatcher’s knowledge of where a passenger wants to travel before the passenger enters the car and the dispatcher’s ability to communicate an individual car assignment to each passenger. The quality and type of performance improvements offered by destination dispatching systems compared to traditional systems depends on the skill of the programmed dispatcher in using the additional information and communication abilities.
It is interesting to note that destination dispatching systems must take an immediate car assignment to the passenger. Unlike traditional two-button dispatching systems which have the luxury of making the actual car assignment at the last second, enabling the system to maximize current system knowledge, destination dispatching systems communicate the car assignment to the passenger immediately and cannot subsequently change it without frustrating the passenger. This may, at times, give a performance advantage to the traditional method of elevator dispatching. In general, however, if the dispatching algorithms have been designed appropriately, destination dispatching systems can give comparable or superior elevator performance over an observed period of time.