Design of Man-machine Communication for Process Automation

Abstract In recent years the functional possibilities and in this way, the range of information processing of process control systems have increased by ten folds due to the use of distributed microprocessor systems. But the information processing capacity of the operator has remained the same as before. To avoid information owerflow of the operator we must carefully plan his work. This concept should be designed in the early stages of an automation project as it concerns the narrowest functional potential. To be able to do this methods have to be at hand for requirement specification of man-machine tasks and symbols to illustrate these functions in technological schemes and so on. Both of them are needed as a basis for calculating the total information load of the operator (sum of all control channels of the whole plant) and for ensuring the performance capability of each single task (channel). To prove the requirements of human operation a CAD module is described. It considers the capability of an operator to carry out the specified tasks. This module compares the required time constants of each function to be carried out with those of a trained operator. If this calculation leads to the result that the time constant relations required are beyond human possibilities an alarm signal will be given. The next step is to sum up all parameters of required human activity to ensure that the balance is within the executable range. If this condition is not true another alarm signal will occur. Thus all functions concentrated on the operator's desk are to be controlled. Main items of human operation are to act as a redundancy in case of instrument failure. For this problem the CAD module uses probability information about the reliability of instruments and the consideration of degradation of a system by partial failure.