Study And Implementation Of Non-contact ECG Monitoring System For Vehicle Drivers

Fatigue driving is one of the core reasons of traffic accident. Be different from other dangerous driving, fatigue driving poses a particular threat to the personal safety of drivers because it is characterized by concealment and thus hard to be detected. Therefore, it is of great significance to reduce traffic accidents and protect drivers’ physical security by studying how to prevent fatigue driving.As a complex biological phenomenon, there is no effective way to detect driving fatigue in the world till now. Studies have shown that a variety of indexes of ECG (electrocardiography) are related to the fatigue degree of the body, which indicates that it can meet the goal of detecting fatigue driving by monitoring ECG signal of the driver. However, the traditional ECG detection methods need to paste electrodes on the skin of the subject and the particularity of the driving environment do not allow such traditional methods. It is always a bothering problem to monitor ECG signal of drivers through their clothes and then evaluate their fatigue degree under the circumstances of ensuring driving safety.In this paper, a prototype of ECG monitoring system for vehicle drivers was designed based on a new kind of capacitive electrode and a normal earth electrode. In this system, the capacitive electrode was made from double sided PCB, and was set on the driver’s seat as the signal electrode. The earth electrode, which was allocated on the periphery of left semicircle of the steering wheel for the purpose of contacting the left hand of the driver in the driving process, was made from thin copper with the thickness of0.2mm, connecting to the analog ground of the circuit. Interference that arised from movement of the driver’s upper body can be minimized by this kind of electrode configuration. The driver was wearing regular clothes to drive the car, and ECG signal was coupled to the input terminal of the forward amplifier circuit by the capacitive electrode. After process of the filter and the amplifying circuit, the original ECG signal was purified and amplified to about IV. An analog-to-digital converter (ADC) sampled the processed ECG signal at a rate of1000Hz to digitalize the signal. Then, the digital signal was sent to a PC by MCU through RS232serial port. In the PC, an application based on Lab VIEW was developed for data display and storing. Finally, simulation experiment in the laboratory and experiment in real driving condition was conducted for the system designed in this paper respectively, and the results indicated that the system has reached the design requirements about functionality, and has a certain theoretical and practical value.