3) Sensor Signal Estimation Results: We have performed
the strain gauge sensor signal estimation by the sensor signal
observer. The flexible arm is controlled by a stabilizing controller
and plant parameters are listed in Table I. Superscripts
+ and − represent clockwise and counter-clockwise, respectively.
Fig. 5 depicts the sensor signal estimation result after
convergence of K. Fig. 5 shows that the sensor signal observer
estimates Sd well after convergence of K. Next, we performed
the sensor signal estimation with load change to confirm the
robustness against the model deviation. The estimation result