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KEYWORDS: Controller, operator, interface, representation

This problem originated as a controller for a conveyor carrying umber to be sorted into bins. Since it is typical of sorting conveyor-bin problems, the parameters of the lumber system will be used. The problem is presented for its practical significance and its interesting human interface and representation problems.

A production process creates items to be placed in 63 bins. When an item is placed on the conveyor, it is given an tem number which identifies the bin into which it is to be placed. Faulty items are also placed on the conveyor and transferred to a reject-bin, t is assumed that the conveyor moves in discrete steps, and after each step, a new item is placed on the conveyor and all items move up one position. if items opposite new bin positions have the corresponding item number, they are ejected into the respective bins. A diagram of the system is shown in Figure BIN-1


Fig. BIN-1. Flow diagram for a conveyor-bin-system.

The bins are of two types: those with a finite capacity which is set when the process is initialized, and those which are open-ended and have an infinite capacity. This latter type is used for the reject bin and may be used in other positions. When a bin is filled, any items which are assigned to that bin ride to the end of the conveyor and are placed in a special holding hopper called the Unbinned items hopper. After some fixed number of items are placed in this hopper, an alarm is given which can be used to stop the system so that the bins can be emptied and the items in the holding hopper placed on the conveyor again. Each time an attempt is made to place an item in a bin that is filled, a signal is given to indicate the condition.


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