Ferromagnetic Shape Memory Microscanner System for Automotive Applications

Daniel Brugger 1Manfred Kohl 1U. Hollenbach 1A. Kapp 2C. Stiller 2

1. Forschungszentrum Karlsruhe, IMT, Postfach 3640, Karlsruhe 76021, Germany
2. Universität Karlsruhe (TH), Institut für Mess- und Regelungstechnik, Engler-Bunte-Ring 21, Karlsruhe 76131, Germany

Abstract

This paper reports on a microscanner system for scanning unknown environments with respect to angle and distance. The main components of the system are a ferromagnetic shape memory (FSMA) microactuator, a mirror for beam deflection, an integrated angle sensor, a pulsed laser diode and a time-of-flight measurement device for distance acquisition. The microactuator consists of a double-beam cantilever, which is fabricated by RF magnetron sputtering of a Ni-Mn-Ga thin film and subsequent photochemical micromachining. Depending on the temperature of the microactuator, either the ferromagnetic or the shape recovery forces dominate, which allows direct electrical actuation in two opposite directions with low biasing forces. The angle sensor is realized by integration of the microactuator on an optical bench including a beam splitter for partial reflection of the optical beam and a position sensing detector.

In the paper, the performance characteristics of the FSMA microactuator and angular sensor will be discussed first. The actuator can be operated with tunable frequencies, which can be categorized in an off-resonance regime below a thermal cut-off frequency of about 100 Hz and a broad resonance regime between 160 and 220 Hz. Furthermore, two optimum regimes of heating power exist, where a large net-force in both directions and thus a large actuation stroke is generated. The typical scanning angle and angular resolution are about 50 and 0.5, respectively. Further investigations are concerned with time-of-flight measurements and the two-dimensional scanning performance. The maximum scanning range is about 30 m for cooperative (reflecting) objects. The distance resolution is about 20 cm. The point clouds generated by the system are subject to further signal processing for segmentation, classification and tracking of objects. The small system size and associated small moving masses are particularly interesting for mobile applications such as vehicle environment sensing

 

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Presentation: poster at E-MRS Fall Meeting 2005, Symposium C, by Daniel Brugger
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-03 09:16
Revised:   2009-06-07 00:44