Proceedings Article | 28 April 2011
KEYWORDS: Actuators, Shape memory alloys, Atrial fibrillation, Reflectors, Light sources and illumination, Headlamps, Ultrasonics, Lamps, Roads, Solid state electronics
Adaptive Frontlighting Systems (AFS in GM usage) improve visibility by automatically optimizing the beam pattern
to accommodate road, driving and environmental conditions. By moving, modifying, and/or adding light during
nighttime, inclement weather, or in sharp turns, the driver is presented with dynamic illumination not possible with
static lighting systems
The objective of this GM-HRL collaborative research project was to assess the potential of active materials to decrease
the cost, mass, and packaging volume of current electric stepper-motor AFS designs. Solid-state active material
actuators, if proved suitable for this application, could be less expensive than electric motors and have lower part
count, reduced size and weight, and lower acoustic and EMF noise1.
This paper documents Part 1 of the collaborative study, assessing technically mature, commercially available active
materials for use as actuators. Candidate materials should reduce cost and improve AFS capabilities, such as increased
angular velocity on swivel. Additional benefits to AFS resulting from active materials actuators were to be identified
as well such as lower part count. In addition, several notional approaches to AFS were documented to illustrate the
potential function, which is developed more fully in Part 2.
Part 1 was successful in verifying the feasibility of using two active materials for AFS: shape memory alloys, and
piezoelectrics. In particular, this demonstration showed that all application requirements including those on actuation
speed, force, and cyclic stability to effect manipulation of the filament assembly and/or the reflector could be met by
piezoelectrics (as ultrasonic motors) and SMA wire actuators.
