I have been working on arduino + piezo vibration sensor to detect the stress amount. Basically the sensor will attached to helmet and when the rider crashes and hits his/her head to the ground the sensor will detect the amount of vibration and sends information to the android application. And the application will compare the range of vibration, if it higher than the limit then the application starts calling 911, police or the riders' relatives. I have two types of piezo vibration sensors: Piezo Vibration Sensor - Small Vertical and Piezo Vibration Sensor - Large with Mass.
The problem with both sensors is that they are extremely sensitive. As you know analog inputs read from 0-1024 (0v-5v), however, since the sensor is too sensitive for a small touch it gets to the limit (1023)
Is it possible to make them less sensitive, so that I could set the range ex.: if the hit level is less than let's say 300 then do nothing. if the amount is higher than 500 then think it as an accident and call these numbers.
FYI, I also used diodes to convert negative voltage to positive.
Your help is much appreciated. Thank you!