Abstract
An adaptive driving beam (ADB) for vehicle headlights has been developed using a microelectromechanical systems optical scanner. A piezoelectric scanner is constructed using thin-film lead-zirconate-titanate oxide (PbZrTiO3, PZT) on a bonded silicon-on-insulator (SOI) wafer, respectively, processed by ion-milling and deep reactive ion etching. The PZT layer is laminated in metal films on the SOI layer to form a piezoelectric unimorph actuator, which are then arranged as a pair of twisting suspensions to drive the scanner at resonance. The same piezoelectric actuators are also arranged into another form of meandering suspensions to generate a large deflection angle. By the combination of these two mechanisms, two-dimensional optical scanner is constructed in a single chip. The scanner is used to draw a Lissajous pattern of a blue laser light on a phosphor material to create a structured light source that is projected forward for illumination. The lighting patterns and positions are electronically controlled and reconfigured depending upon the location of leading/oncoming vehicles, pedestrians, road signs, and the cruising speed of the vehicle. The paper discusses on the design of the piezoelectrically driven optical scanner along with the optomechanical performances. We also report on the road-test result of the developed on-vehicle ADB module.
Highlights
Adaptive driving beam (ADB) is an advanced drive-assist technology for an automobile headlight that provides drivers with visibility of high contrast and illuminance at night without causing temporary blindness to other drivers in a projected light’s glare.[1,2] Different from the classic headlight with manually switchable low- and high-beam modules, the ADB system throws reconfigurable light depending upon the cruising speed and the traffic environments such as presence of oncoming or leading vehicles, pedestrians, and traffic signs that are automatically recognized by the on-board computer vision system
With the development of the automatic visual recognition technology, the ADB has become a part of the autonomous driving system to provide the driver with the best illumination patterns by automatically recognizing the leading/ oncoming vehicles, pedestrians, and road signs
We performed adaptive lighting to visualize a pedestrian standing by the oncoming vehicle without projecting a glare light to the other driver
Summary
Adaptive driving beam (ADB) is an advanced drive-assist technology for an automobile headlight that provides drivers with visibility of high contrast and illuminance at night without causing temporary blindness to other drivers in a projected light’s glare.[1,2] Different from the classic headlight with manually switchable low- and high-beam modules, the ADB system throws reconfigurable light depending upon the cruising speed and the traffic environments such as presence of oncoming or leading vehicles, pedestrians, and traffic signs that are automatically recognized by the on-board computer vision system. An array of light-emitting diodes,[4,5,6] for instance, is used in the commercialized ADB optics that changes the projected light patterns in a digital manner. Due to the SLM mechanism that is based on light blocking, the light power that is not projected forward is consumed as heat loss in the headlight module. As an alternative solution for ADB, we have developed a microelectromechanical system (MEMS) two-dimensional optical scanner to produce various illumination patterns on a phosphor luminescent material, which are projected forward through the imaging lenses. A test module of ADB headlight is assembled with the scanner, and field-tested to demonstrate the cruise-speed dependent illumination and the pedestrian recognition by the patterned lighting. This paper includes the extended results based on the technical reports presented at IEEE OMN 201910 and ISAL 2019.11
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