A three-component model of the control error in manual tracking of continuous random signals.
OBJECTIVE
The performance of human operators acting within closed-loop control systems is investigated in a classic tracking task. The dependence of the control error (tracking error) on the parameters display gain, k(display), and input signal frequency bandwidth, f(g), which alter task difficulty and presumably the control delay, is studied with the aim of functionally specifying it via a model.


BACKGROUND
The human operator as an element of a cascaded human-machine control system (e.g., car driving or piloting an airplane) codetermines the overall system performance. Control performance of humans in continuous tracking has been described in earlier studies.


METHODS
Using a handheld joystick, 10 participants tracked continuous random input signals. The parameters f(g) and k(display) were altered between experiments.


RESULTS
Increased task difficulty promoted lengthened control delay and, consequently, increased control error.Tracking performance degraded profoundly with target deflection components above 1 Hz, confirming earlier reports.


CONCLUSIONS
The control error is composed of a delay-induced component, a demand-based component, and a novel component: a human tracking limit. Accordingly, a new model that allows concepts of the observed control error to be split into these three components is suggested.


CONCLUSIONS
To achieve optimal performance in control systems that include a human operator (e.g., vehicles, remote controlled rovers, crane control), (a) tasks should be kept as simple as possible to achieve shortest control delays, and (b) task components requiring higher-frequency (> 1 Hz) tracking actions should be avoided or automated by technical systems.
Bundeswehr University Munich, Institute of Communications Engineering, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany. hans.gerisch@unibw-muenchen.de
Hans
H
Gerisch
Gerhard
G
Staude
Werner
W
Wolf
Gerhard
G
Bauch
D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008328:Man-Machine Systems; D013647:Task Performance and Analysis; D055815:Young Adult