Table 1 Comparison of control methods of AT for patients with neurological disorders affecting either mobility or communication. EOG=Electrooculogram, EEG=Electroencephalogram, EMG=Electromyography

Eye-gaze

Uses a person’s eye movements for control sensed by either a camera [5, 9] or EOG [21,22,23]

Usable with severe conditions [8, 24]

Fatigue [25], needs visual attention

Brain signals

Based on decoding electrical signals produced by the brain, sensed by electrodes placed on the head. Either invasively under the skull [26] or non-invasively on the scalp using EEGs [10, 27].

More natural control [28], usable with severe conditions [27, 29]

If non-invasive low accuracy on complex tasks, expensive [30], pre-training needed [31], mentally exhausting [32]

Hand/facial muscles sensed by EMG

Using muscles in hand [33] and face [34, 35] that still at least partially work sensed by EMG

Easy to use, controlled by simple movements, such as eyebrow raise [36]

Not suitable in severe conditions, difficulty of correct electrode placement [35]

Head/chin movement

Either following movement of target fixed on forehead [37] or placing chin on sensors and moving around (joystick) [38,39,40]

Low cost, high accuracy for controlling direction

Fatigue, can not be used with severe conditions, or with conditions with tremors

Tongue movement

Using tongue movements directed towards sensors placed on the top of the mouth [41, 42]

Usable with severe conditions [43], invisible control, range of inputs [43]

Uncomfortable

Sip and puff switch

Controlling by breath sensed by pressure sensors [6, 44, 45]

Easy to use, portable

Not suitable if respiratory or pulmonary functions are affected, needs frequent maintenance (cleaning), obstructive

Tooth-click controller

Using tooth-clicking for control sensed by either an accelometer placed behind the ear detecting jaw vibrations [46] or detecting the sound of the clicking [47]

Easy to use, comfortable, easy to learn

Not suitable in severe conditions

Voice control

Using speaking or sounds for control [12, 48, 49]

High speed [49]

Not suitable if speech is impaired [50], not practical in social settings as other sounds can interfere, and could disturb others