-ci ASPECTS OF COMPUTER CONTROL FROM THE HUMAN ENGINEERING STANDPOINT*

A Computer Control System includes dataacquisition, information display and output control signals. In order to design such a system effectively we must first determine the required operational mode: automatic control (closed loop), computer assisted (open loop), or hybrid control. The choice of operating mode will depend on the nature of the plant, the complexity of the operation, the funds available, and the technical expertise of the operating staff, among many other factors. Once the mode has been selected, consideration must be given to the method (man/machine interface) by which the operator interacts with this system. The human engineering factors are of prime importance to achieving high operating efficiency and very careful attention must be given to this aspect of the work, if full operator acceptance is to be achieved. This paper will discuss these topics and will draw on experience gained in setting up the computer control system in Main Control Center for Stanford University's Accelerator Center (a high energy physics research facility). (In this complex system both open and closed loop computer controls are used, as well as large numbers of manual functions. 1. Computer full automatic control--Digital, analog, linear or non-linear data and information is acquired from devices and fed into the computer. The computer actuates the devices based upon those data and information as programmed. It is also programmed to make corrections within set limits. If a condition has been changed outside of these set limits for any reason, the whole process will come to a halt. The human operator will diagnose the problem and make a decision whether to clear the faulty situation or reprogram the computer. This scheme is known as "closed loop" control system.