Abstract: A headrest has a generally stationary support, a headrest body having a forwardly directed front face and positioned such that a head of a user seated in front of the support is generally level with the body, and a guide securing the body to the support for vertical movement relative to the support. A drive can vertically shift the body relative to the support. A sensor assembly has at least three horizontally elongated and vertically spaced electrodes carried on the front face. A controller connected to the electrodes and to the drive means detects a vertical position of the user's head relative to the body and displaces the body so as to centrally align with the user's head.

Abstract: A radar device secured to a vehicle includes a transmitter for broadcasting continuously frequency-modulated radar signals over a time range. The time range is fixed as a function of a speed of the vehicle and is longer at a higher speed and shorter at a lower speed. A receiver receives the radar signals. An evaluation circuit compares the transmitted and received radar signals to ascertain information about the surroundings and in particular a distance from and a relative speed with respect to an object.