Integration and operational strategy of a flexible automated system for sample analysis

This project describes the integration of a twenty-two workstation laboratory automation system based around a track-mounted robot. The required level of operational flexibility
of the overall system puts the emphasis on interfacing and controlling effectively a large number of instruments. The integration of such a large system can sometimes be tricky
as off-the-shelf instruments are put near side modified commercial equipment and purpose built workstations.
The automated system being developed at Rhone-Poulenc Agriculture Ltd (RPAL) automates several highly manual analytical processes following one another in a constantly varying order. The integration of such a system was carried out in collaboration with a software and a mechanical engineer. The choice of the controlsystem was made so that the variety of workstations included could be controlled by a
limited number of different means. After having drawn the specifications and estimated the number of inputs/outputs needed for every station, a PLC was acquired together with
four computers. Various electronics interfaces had to be built or purchased in order to fully operate the system from the controlling computers. Printed circuit boards have been designed and manufactured at Middlesex University together with many mechanical parts for different stations. This integration had to make sure that the system will operate as intended and governed by the parameters entered by the user. System's behaviour and safety in case of an error or an emergency was studied and an emergency stop circuit together with interlocks was implemented. The PLC program was designed so that the machines will fail safe in case of a problem. Being a tool for method development and optimisation, the system evolves gradually towards becoming an expert system. From the information gathered during runs, a decision tree is implemented and responsibilities are gradually withdrawn from the user. Cross-contamination, radio-labelled samples, and solvent compatibility are determining
factors in the safety evaluation and validation processes. This system was developed as part of a three year Teaching Company Scheme collaboration project between Middlesex University and RPAL. The diversity of the task required the participation of three engineers with varying skills: mechanical, software, and electronics.