Wireless Sensor and Actuator Networks for Lighting Energy ...

Table 8-2 Summary of the test on preferred overriding mechanism.
Easy to learn
Easy to use
Handheld remote
controller
Graphical user
interface (GUI)
Agree 10 10
Neutral 0 0
Disagree 0 0
Agree 8 10
Neutral 0 0
Disagree 2 0
Preferred mechanism 2 7
From Table 8-2, it can easily be concluded that both overriding mechanisms
were reasonably easy to learn and use for setting the participants’ preferred lighting.
The GUI provided by the research system was generally considered to be more versatile
than the handheld remote controller due to the various overriding options. The handheld
remote controller was designed to increase or decrease the light level of the Watt
Stopper system in a continuous manner following a gentle curve. As a result, users had
to aim at the photosensor and keep on pressing the button on the controller until the
light reached a satisfying level. Comments on the questionnaires indicated that the slow
response led two subjects to disagree on the easiness of use of the handheld remote
controller.
Seven participants preferred the GUI provided by the research system over the
handheld remote controller while two subjects had the opposite opinions. One
participant didn’t express a specific preference on either type of the overriding
mechanisms. People preferred the GUI mostly because they could easily control the
lights while working on the computer without being distracted by having to locate a
physical device for this purpose. On the contrary, people who rated the handheld remote
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