Experimental Study of Laser Interferometry Based Motion Tracking of a Flexure-Based Mechanism

Introduction

Ultra-precision manipulation is one of the very important techniques for the micro/nano engineering and for many applications in manufacturing and medical sciences. Precise control and accurate motion tracking at micro/nano level is a requirement for present and future automation systems. Such precise actuation and control can be achieved with piezoelectric actuator driven flexure-based mechanisms. These mechanisms are highly appropriate platforms for micro/nano manipulation (Chung, Choi, & Kyung, 2006; Li & Xu, 2010; Spanner & Vorndran, 2003; Speich & Goldfarb, 1998; Tian, Shirinzadeh, & Zhang, 2009). Flexure-based mechanisms have no backlash, zero friction and negligible hysteresis, and can offer unlimited motion resolution (Paros & Weisbord, 1965; Mohd Zubir & Shirinzadeh, 2009; Smith, 1997; Tian, Shirinzadeh, & Zhang, 2010). However, piezoelectric actuators possess non-linearities including the hysteresis and creep/drift effects. The presence of such non linearities cannot guarantee positioning accuracy and precise motion tracking of the flexure-based mechanism. However, in the past decade, increased demand for high-precision micro/nano motion tasks has generated high level of research interests in precise positioning and accurate motion tracking of micro/nano manipulators. Many appropriate closed-loop control strategies have been proposed to achieve the desired motion tracking of piezoelectric actuator-driven flexure-based mechanisms (Bashash & Jalili, 2008; Liaw & Shirinzadeh, 2008, 2009; Motamedi et al., 2010; Rakotondrabe, Haddab, & Lutz, 2009; Saeidpourazar & Jalili, 2006; Shiou et al., 2010; Xu & Li, 2009, 2010). An important component associated with closed-loop control of micro/nano multi-axis manipulator is the sensing and measurement of motion characteristics. Use of interferometry-based sensing to measure changes in position, length, distance and optical length is well demonstrated in recent past (Sommargren, 1987; Speckle 2010; Optical Metrology, 2010). Laser interferometry-based sensing and measurement system is capable of delivering sub nanometer accuracy when used for displacement measurement (Lee, Yoon, & Yoon, 2011; Minoshima, 2010; Schott, 2010; Schuldt et al., 2010; Shelley, 2007; Zeng & He, 2009; Zhou, Zhang, & Cheng, 2009). There has also been a number of research studies carried out on laser interferometry-based motion control for flexure-based mechanisms (Qi, Zhao, & Lin, 2007; Yeh, Ni, & Pan, 2005; Zhang & Menq, 2007) and it shows immense potential for further research.