Plessey has developed a novel solution to monitor driver fatigue that is based on its EPIC sensor technology.
Until recently, measuring ECG in a car meant a set of electrodes were attached to the driver. However, because the EPIC sensor utilizes capacitive coupling, it doesn’t rely on good skin contact and can actually measure ECG through normal clothing and seat cover fabric. By monitoring heart rate variability (HRV), a measure of the stability of the heart rate from beat to beat, it is possible to tell when the driver is starting to become sleepy.
Plessey recommends an array of sensors built into the seat back, so that the optimal sensing location can be chosen, regardless of the driver’s height and build. Movement noise is minimized by placing the sensors away from the shoulders on the lower part of the seat back. The system uses a capacitive driven ground plane, which can also be placed under the seat cover fabric on the base of the seat, to produce a completely hidden system. Further noise reduction can be achieved by coupling this driven ground to the steering wheel. The system has been shown to be immune to electrical noise sources within the car.