Db. Kaber et al., Design of automation for telerobots and the effect on performance, operator situation awareness, and subjective workload, HUM FACT ER, 10(4), 2000, pp. 409-430
In this article we review and assess human-centered level of automation (LO
A), an alternate approach to traditional, technology-centered design of aut
omation in dynamic-control systems. The objective of human-controlled LOA i
s to improve human-machine performance by taking into account both operator
and technological capabilities. Automation literature has shown that tradi
tional automation can lead to problems in operator situation awareness (SA)
due to the out-of-the (control) loop performance problem, which may lead t
o a negative impact on overall systems performance. Herein we address a sta
nding paucity of research into LOA to deal with these problems. Various sch
emes of generic control system function allocations were developed to estab
lish a LOA taxonomy. The functions allocated to a human operator, a compute
r, or both, included monitoring system variables, generating process plans,
selecting an "optimal" plan and implementing the plan. Five different func
tion allocation schemes, or LOAs, were empirically investigated as to their
usefulness for enhancing telerobot system performance and operator SA, as
well as reducing workload. Human participants participated in experimental
trials involving a high fidelity, interactive simulation of a telerobot per
forming nuclear materials handling at the various LOAs. Automation failures
were attributed to various simulated system deficiencies necessitating ope
rator detection and correction to return to functioning at an automated mod
e. Operator performance at each LOA, and during the failure periods, was ev
aluated. Operator SA was measured using the Situation Awareness Global Asse
ssment Technique, and perceived workload was measured using the NASA-Task L
oad Index. Results demonstrated improvements in human-machine system perfor
mance at higher LOAs (levels involving greater computer control of system f
unctions) along with lower operator subjective workload. However, under the
same conditions, operator SA was reduced for certain types of system probl
ems and reaction time to, and performance during, automation failures was s
ubstantially lower. Performance during automation failure was best when par
ticipants had been functioning at lower, intermediate LOAs (levels involvin
g greater human control of system functions). (C) 2000 John Wiley & Sons, I
nc.