A novel and cost effective resistive rain sensor for automatic wiper control: Circuit modelling and implementation

Safety and driver comfort are the essential goals of new trends in automobile industry. An automatic wiper controller, helps not only in increasing safety by reducing distractions but also increases the overall comfort. Such an automatic control is available however it has limitations of high cost and low efficiency. In this work, we have proposed an automatic wiper controller, based on resistive rain sensor which is cost effective, efficient and has a wide range of output. An equivalent electrical and mathematical model of the sensor is developed, simulated and practically verified. The rain sensor has a predetermined geometry. Hence the rain water forms a film on the sensor surface causing its resistance to change non-linearly. To increase the overall efficiency of system, it is necessary to linearize the sensor response. It is achieved using electrical equivalent model of the sensor and with appropriate linearization circuit. Further, a customized embedded system is developed using PIC micro-controller to achieve motor speed variation based on sensor output. The proposed system is rigorously tested on a small segment car (Indica V2) for its performance. It is observed that, the developed system works satisfactorily under various rain scenarios.