Precise trajectory measurement of self-propelled mechanism by $\text{XY}\theta$ three-axis displacement sensor consisting of multiple optical encoders

In this paper, we describe a
$\text{XY}\theta$
three-axis displacement sensor using an optical encoder and its measurement performance. This sensor can measure X, Y, and
$\theta$
displacement, and the measurement limit is
$0.1\ \mu \mathrm{m}$
on the X and Y axes and
$7.35 \times 10^{-4}\deg$
on the
$\theta$
axis. In addition, we also describe a self-propelled mechanism driven by piezoelectric actuator will also be described. This mechanism is palm-sized and extremely compact, and can move freely on a ferromagnetic surface. An experiment that measures the behavior of the mechanism is also described for investigating the applications in bio-medical and MEMS fields