On the scheduling of a multipurpose laboratory analysis instrument

Automated laboratory analysis by the time-resolved fluoroimmuno technique is a modern application of biochemistry and embedded computer technology. The laboratory system is interesting from the point of view of scheduling. The laboratory system, AutoDELFIA, consists of 14 modules which can work partially in parallel: pumper, loader, x-lane, reagent lane, elevator, washer, remover, enhancement dispenser, reagent dispenser, barcode reader, incubator, measurement unit, liquid system and sample processor. the loader, elevator and x-lane are used to move sample plates from one module to another. Each of these three devices may move only one plate at time, and in addition, the x-lane is reserved to hold the sample plate during the operation of the washer, remover or some of the dispensers when the sample plate is processed. This requirement makes the x-lane a bottleneck device that restricts the level of parallelism and performance of the whole system. Restrictions combined with the hard due times of the chemical operations make scheduling a complicated task: the length of the actual make span has to be determined by simulation