Table 2.

Overview of the most recent sensor-based methods.

Location/Type of Sensor	Principle
car seats	monitoring of vital signs, such as cECG, BCG, seismocardiography (SCG) or all at once;
steering wheel	cECG or pulse wave monitoring via conductive systems;
front camera	monitoring of the driver’s face and evaluation of signs of fatigue, such as frequent blinking, eyes closing or head dropping;
back camera	monitoring of horizontal and vertical traffic signs, detection of lane deviations and traffic restrictions; in cooperation with the front camera, tracing the driver’s view and determines whether he has registered the vertical traffic sign with the view; detection of time of collision with an obstacle in front of the vehicle;
helmet	included in a test phase; monitoring of the driver’s condition through the EEG.