This paper describes the mechanical, electrical, computer, and software systems of a prototype computer controlled drilling rig. The rig has operated under computer control for over three years on a project investigating optimized turbine control. In addition to describing the advantages and the basic computer control features of the rig, this paper presents the practical problems for computer controlled drilling and suggests possible solutions to these difficulties.

In the past, several attempts at full computer control of the drilling process have been made, but all have ultimately proven to be short lived. Recent advances in the power and reliability of sensors and computer control hardware, as well as reductions in their cost, have brought computerized rig control closer to reality. However, some important hurdles remain.

It is the authors' experience that most of the hurdles lie on the electrical and mechanical side of the system. Computer hardware and software capabilities have improved to the point that almost any function can be economically programmed. However, problems with sensor reliability and calibration, and actuation still exist. Each of these problem areas is discussed in this paper.

In summary, the purpose of this paper is: (1) to describe the use of a computer controlled rig, (2) to describe the problems the authors have experienced during three years of computer controlled drilling, (3) to present possible solutions to these problems, and (4) to discuss the future for field use of computer controlled drilling.

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