Page 133 - Handbook of Biomechatronics

130 Domen Novak

and they were used by Robocop to control his prosthetic limbs in the 1987
movie. While these applications may have seemed far-fetched at the time,
scientists have now developed actual functioning prototypes of BCI-
controlled wheelchairs, prostheses, and other biomechatronic devices.
However, real-life BCIs are also prone to errors and lack intuitiveness,
and thus have not yet achieved widespread use. In this chapter, we briefly
review the functional principles of BCIs, their advantages and disadvantages,
and existing prototypes in a number of biomechatronic applications.

1 BCI MODALITIES AND SIGNALS
Most state-of-the-art BCIs are based on electroencephalography
(EEG), a noninvasive measurement of the brain’s electrical activity obtained
from the scalp (Section 1.1). However, BCIs can also utilize invasive elec-
trical measurements (Section 1.2) or hemodynamic measurements
(Section 1.3), and multiple sensing modalities can be combined for better
performance (Section 1.4).
1.1 Electroencephalography

EEG is the use of electrodes placed on the scalp to measure the electrical
activity of the brain ( Jackson and Bolger, 2014). This electrical activity arises
from synchronized synaptic activity in populations of cortical neurons

Fig. 1 A person uses an electroencephalography system to play a computer game.
(Courtesy Cybathlon, ETH Zurich. Photographer: Alessandro Della Bella.)