Novel Use of a Piezoelectric Ultrasonic Motor for Headlamp Leveling

The driver must always have clear visibility and the Automatic Headlamp Levelers (AHL) are one among several devices used to enhance vision in dim conditions. Typically, dynamic levelers use a stepper motor and present intrinsic play due to the utilization of geared mechanisms that transform the initial rotational movement in a linear one. However, some scenarii or even some lighting applications require a higher dynamic behavior with higher precision and repeatability for adjusting the headlamp cut-off, e.g. rough terrain driving, long range illumination with high power sources, etc. In this paper, we study the use of a piezoelectric motor as an actuator for dynamic headlamp leveling, a mechatronic actuator that may be the next step in automotive lighting. The paper describes an experimental setup for headlamp leveling using a piezoelectric motor and a first evaluation of the results. The system may be used to compensate the short time pitch angles caused by the driving dynamics besides offering ultra-high precision of ±0.003°.