Table 1.
Comparison of control methods of AT for patients with neurological disorders affecting either mobility or communication. EOG=Electrooculogram, EEG=Electroencephalogram, EMG=Electromyography
| Control type | Working principle | Strength | Limitations |
|---|---|---|---|
| Eye-gaze | Uses a person’s eye movements for control sensed by either a camera [5, 9] or EOG [21–23] | 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) [38–40] | 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 |