The research of expressway vehicles collision warning systems based on millimeter wave radar

The field of communications and transport has become the artery, which bears the weight of society development. Safety, speed and comfort are the goals of the traffic development. But with the quick development of the traffic field, Safety becomes a serious problem, which restricts the further development of the traffic field. It is very important research and development of methods to prevent traffic accidents. Developing the avoidance system is one of the efficient methods to decrease collision accidents on expressway. Many front-end collisions are due to the driver paying insufficient attention, or leaving insufficient distance to the vehicle in ftont. The new system can automatically warn the driver of a possible collision with another vehicle in ftont, and to reduce the impact energy as much as possible in the event of a collision. Millimeter wave radar is used to measure the distance and its relative speed to the vehicle in front. First, a new vehicle safety distance model is established according to the different stages of braking. This arithmetic is able to support drivers to predictive their danger earlier. On the view of the selection and design of wave form, new wave form named multi-frequency symmetrical saw-tooth wave is proposed to get better system response characteristic than conventional triangle waveform. Positive and negative frequency modulation signals of the new wave form are transmitted synchronously. So the whole measurement time is shortened and system response characteristic is enhanced. The theoretical analysis results prove that the new waveform and algorithm can detect multi-target correctly. It can operate stably in adverse weather conditions. The simulation results show that the system can correctly detect vehicles driving ahead in the same lane with higher than 99% accuracy in clear weather.