Research Needs for Human Factors (1983) / Chapter Skim
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Pages 49-77
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From page 49... ...
4 SUPERVISORY CONTROL SYSTEMS In the pant IS years the introduction of automation into working environments has created more and more jobs in which operators are given very high levels of responsibility and very little to do. The degree of responsibility and the amount of work vary from position to position, but the defining properties of such jobs are: (1)
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From page 50... ...
The human factors problems involved in supervisory control systems can be classified into five categories.
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From page 51... ...
We have no good principles of job design for operations in supervisory control systems, in part because it has proved extremely difficult to measure or estimate the mental workloads involved. They tend to be highly transient, varying from light and boring when the work is routine to extremely demanding when action is critical.
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From page 52... ...
. Because there are many more interactions than the number of variables, the variety of displayed signals and the number of possible adjustments or programs the human operator may input to the computer-controller are potentially much greater than before.
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From page 53... ...
Not only were the manual control loops themselves stabilized by electronics, but also nonmanual, automatic control functions were being simultaneously executed and coordinated with what the astronauts did. In commercial and military aircraft there has been more and more supervisory control in the last decade or two.
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From page 54... ...
Air traffic control poses interesting supervisory control problems, for the headways (spacing) between aircraft in the vicinity of major commercial airports are getting tighter and tighter, and efforts both to save fuel and to avoid noise over densely populated urban areas require more radical takeoff and landing trajec~ories.
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From page 55... ...
m e human operator may have other things to do, so that supervisory control would facilitate periodic checks to update the computer program or help the remote device get out of trouble. A final reason for supervisory control, and often the most acceptable, is that, if communications, power, or other systems fail, there are fail-safe control modes into which the remote system reverts to get the vehicle back to the surface or othew~se render it recoverable.
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From page 56... ...
. THEORY AND METHOD There are a number of limited theories and methods in the human factors literature that should be brought to bear on the use of supervisory control systems.
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From page 57... ...
me third takes up computer knowledgebased systems and their relation to the internal cognitive model of the operator for on-line decision making in supervisory control. The fourth deals with mental workload, stress, and research on attention and resource allocation as they relate to supervisory control.
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From page 58... ...
3. t TasK 35 olive a',=~t~ OY human operator Task ~ o~'arved Indirectly through sensors computers and disolavs This TIS tecaback Interacts vv th HIS tow - Ck Task Is controlled - ,th,n TIS automatic Moe 4 Task Is affected ~y the orocms of being "need 5 Task aftec~s actuators and in turn Is aftactee lit Human operator directly affects task 7 Hu'Tun orator affects teak Indirectly through control' HlS communes and actuators This control interact with that from TIS Human o~cre~or gets Aback from HIS 9 I.lumen operator adjusts control parameters 1 O
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From page 59... ...
| | ~:~ ~ | | | | | | | I | | I ~ I i i extension of | S'|S2is3iollo2lo3lR'lR2l 31 | | | | | | behavior I 1 ~13 / TASK 1 \ /~ TASK 2 \ / TASK 3 I/ \ ~\ ~\ FIGURE 4-2 Multilevel Allocation of Tasks in a Supervisory Control System
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From page 60... ...
Although good-quality computer-generated speech is both available and cheap, and although it can give operators warnings and other information without their prior attention being directed to it, little imaginative use of such a capability has been made as yet in supervisory control.
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From page 61... ...
Perhaps in supervisory control systems the equivalent functions should be separated, and different training and temperament called for in monitoring and in intervention. Computer Knowledge-Based Systems and the Operator's Internal Cognitive Model It is not a new idea that, in performing a task, people somehow represent the task in their heads and calculate whether, given certain constraints, doing this will result in that.
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From page 62... ...
Cognitive Science In the last several years cognitive psychology has contributed some theories about human inference that make the application of knowledge~based systems particularly relevant to supervisory control. The idea is that reasoning and decision making consist of the developing and searching of complex problem spaces (Newell and Simon, 1972)
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From page 63... ...
How can we determine a given operator's internal cognitive model of a given task at a given time? One method is to ask the operator to express it in natural language, but the obvious difficulty is that each operator's expression is unique, making it very difficult to measure either discrepancy from reality or to compare across operators.
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From page 64... ...
Mental Workload The concept of mental workload as discussed in this section is not unique to supervisory control, but it is s Of f to iently important in this context to be included here as a spec ial cons iteration. Human-Machine Control (= is section is adapted from Sher idan and Young, 1982 )
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From page 65... ...
Perhaps more interesting is a three-attribute scale, there being some consensus that Fraction of total time busy, n Cognitive complexity, and "emotional stress. are rather different characteristics of mental workload and that one or two of these can be large when the other(s)
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From page 66... ...
Finally, it may be possible to give all or part of the task to a computer or automatic system. Cognitive Science It is important, for purposes of evaluating both mental workload and cognitive models as discussed in the previous section, to note that there has been an enormous change in models of mental processing in both psychology and computer science.
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From page 67... ...
We also know more about the role of subcortical and cortical structures in motor control. The study of mental workload has simply not kept up with these advances in the conceptualization of the human mind as a complex of subsystems.
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From page 68... ...
mere is also an obvious connection between a cognitive systems approach and analysis of individual differences based on psychometric or information processing concepts, and much needs to be done to link analysis of individual abilities to the ability to time-share activity within the same cognitive system or across different systems (Landman and Hunt, 1982)
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From page 69... ...
Again, its applicability has not been evaluated in more complex tasks in which s ignals are represented by more complex patterns of activity as would be the case in supervisory control systems of the types described above. Human Proficiency and Error: Culpability, Trust, and Ultimate Authority Designers of the large, complex, capital-intensive, high-risk-of-failure systems we have been discussing
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-- without adequate feedback to tell them when they are in error. m ey would have supervisory control system" designers provide feedback at every potential misstep.
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Presumably the rationale for defining human error is to develop means for predicting when they are likely to occur and for reducing their frequency (Swain and Gutman, 1980)
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From page 72... ...
In addition to these fundamental research needs, there in a variety of related issues particularly relevant to supervisory control systems that should be addressed. In supervisory control systems it is becoming more and more difficult to establish blame, for the information exchange between operators and computers is complex, and the ~error,.
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From page 73... ...
. CONCLUSIONS AND RECOMMENDATIONS Supervisory control of large, complex, capital-intensive, high-risk systems is a general trend, driven both by new technology and by the belief that this made of control will provide greater efficiency and reliability.
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Why people make errors in system operation, how to minimize these errors, and how to factor human errors into analyses of system reliability. Bow mental workload affects human error making in systems operation and refinement and standardization of definitions and measures of mental workload.
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From page 75... ...
1979 Cortical maps and visual perception. Quarterly Journal of Experimental Psychology 31:1-17.
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O G 1980 Human operator control of slowly responding systems: supervisory control.
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From page 77... ...
New York: Plenum Press. Supervisory Control: Problems, Theory and Experiment in Application to Undersea Remote Control Systems.
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