a pressure transducer is attached along the circumference of the steering wheel of a vehicle and measures total hand grip pressure on the wheel . a control unit having a microcontroller monitors the variable pressure signal from the transducer and sounds an alarm when the pressure falls below a lower limit and when the transient behavior of the pressure signal deteriorates substantially . a display unit , attached to the steering wheel and having a number of led &# 39 ; s , gives a visual indication of the driver &# 39 ; s drowsiness level .