Adaptive Cruise Control Collision Warning with Brake Support

Abstract

This project consists of a handheld range finding device using ultrasonic transducer and an LPC2148. A
two-line LCD display is used to display the measurements. There is a 40 kHz transmitter and receiver. The 40 kHztransmission signal is generated via a square wave outputted from the LPC2148 . The LPC2148 is then used to calculate
the time of flight (TOF) for the sound wave that is bounced off of distant objects. The return signal is amplified using two
opamp amplifiers. There are three potentiometers that need to be calibrated for correct operation. One controls the
contrast of the LCD display. Another controls the amplification of the third stage of the amplifier system. The third
controls the voltage offset that connects to the base of a NPN switching transistor. The measurement range of the device
is one to ten feet. Further distances can be measured, but due to circuit noise erroneous measurements can be obtained
for longer distances. The absolute maximum range that can be measured is about twenty feet.