Capacitive seat detects drowsy drivers
Sleepy drivers could be warned by electrostatic non-contact heart rate sensing, claims Plymouth-based Plessey Semiconductors.
According to the firm, it is possible to tell when a driver is starting to become sleepy from beat to beat heart rate variability.
The firm’s proprietary sensing technology, branded EPIC, is capacitive and can detect body electricity, from the heart for example.
“It doesn’t rely on good skin contact and can measure ECG through normal clothing and seat cover fabric,” said the firm. “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.”
Electric body fields due to movement are minimised by keeping the sensors away from the shoulders.
The proposed system uses a capacitive driven ground plane in the seat beneath the drive. “Further noise reduction can be achieved by coupling this driven ground to the steering wheel. The system has been shown to be completely immune to electrical noise sources within the car,” claimed the firm, “95% of heart beat peaks were detected during a ten minute trial over a variety of driving conditions.”
For car manufacturers and suppliers, there is an evaluation kit with six sensor back pad, a ground plane to sit on, and an interface box with a USB output to display and recording software.