On Board Doppler Sensor for Absolute Speed Measurement in Automotive Applications

Many automotive applications, like anti-lock braking systems (ABS), anti collision radars, airbags, require an absolute speed accurate measurement, especially in high risk situations. On-board Doppler sensors may provide a better answer to such a problem than sensors which measure the speed of rotation of the wheels. Indeed the latter can for instance slide on wet or icy roads. However, conventional Doppler sensors cannot operate when the beam emitted by the radar does not encounter a scattering obstacle on the road surface.

In this paper, we present solutions, tested by simulations and by experiments, which drastically increase the probability of having reflecting obstacles in the antenna footprint of Doppler sensors, leading to accurate measurements.