Originally Posted by
berner
I've just finished reading a biography of Elon Musk which to a large extent is also a biography of Tesla. There were two road fatal incidents with Tesla vehicles where the vehicle failed to recognize trucks crossing in front of the oncoming Tesla which then drove under the trucks shearing off the upper section of the cars. As explained in the book, doppler radar was used to identify movement in front of the Tesla. Evidently, doppler shifts are not good at detecting movement across the direction of travel so the trucks were never "seen" by the radar. The book did not say whether this system has been corrected. What was clear is that billions of dollars are at stake and Tesla is running out of time and money, as usual.
This makes sense - the radar was not pulsed. Pulsed radar directly reads back the distance to a metal object in front of it. Doppler, at least "pure" doppler directly reads back speed. I'm not sure either one is good at detecting pure transverse motion. Hybrid types of radar are now more common in industry, as are systems which blend radar systems with laser or passive optical sensors, and combine the data from multiple sensors to create a comprehensive picture of target motion. A fully-vetted International Standard defines the minimum performance required for detection of possible forward collision objects, and it did not specify what kind of sensor had to be used, rather they specified what the sensor or system of sensors had to detect and what the system had to accomplish. To determine what design, what kinds of sensors are to be used to satisfy the safety requirements, is left to the car companies, to enable the best AND most cost-effective design to be chosen. The car company designs the car, not the ISO International Organization for Standardization. The fact that Tesla failed at that design is, to me, a sign of deficient engineering, and of not finishing the design before releasing it to the public. They also did not realize that owners usually do not read their owners' manuals.