Sharing Control Between Human and Automation Using Haptic
Interface: Primary and Secondary Task Performance Benefits
Paul Griffiths and R. Brent Gillespie
Human Factors, Fall 2005
In this paper, a paradigm for human/automation control sharing is described in
which a machine’s manual control interface is motorized to allow a human and an
automatic controller to exert control simultaneously. The manual interface
becomes a haptic display, relaying information to the human about the actions of
the automatic controller. While monitoring the automation actions, the human may
express his control intentions in a way that either overrides the automation or
conforms to it. Because the human remains tightly integrated in the primary
control task, he retains responsibility and awareness even while giving away a
portion of the workload to the automation. The objective of this paper is to
demonstrate how adding automation by motorizing the manual interface can be used
not only to improve performance on a primary task, but also to reduce perceptual
demands or free attention for a secondary task. Results are presented from 3
experiments in which 11 subjects completed a path following task using a
motorized steering wheel on a fixed-base driving simulator. The automation
system behaved like a co-pilot who had a hand on the steering wheel, could see
the road but not certain obstacles,) and would assist with path following by
applying torques to the steering wheel through a relatively light spring.
Results indicate that haptic assist applied through the steering wheel improves
path following by least 30%, p<0.0001 while either reducing visual demand by
29%, p<0.0001, or improving reaction time in a secondary tone localization task
by 18 ms, p=0.0009. Whereas the presence of a secondary task adversely affected
lane keeping performance without haptic assist, there was no dependence of path
following performance or obstacle avoidance on the presence of a secondary task
with haptic assist.