Real-time laser beam stabilization by sliding mode controllers

Contraction-Based Nonlinear Controller for a Laser Beam Stabilization System Using a Variable Gain

“…From linear control literature, the waterbed effect has been known and recognized by control practitioners where design trade-off must be made in increasing the closed-loop bandwidth and the low-frequency disturbance rejection properties at the cost of deteriorating the sensitivity to high-frequency measurement noise. On the other hand, nonlinear control schemes like nonlinear PID and sliding mode controllers [10] can take into account the low-frequency/bandwidth trade-off. Similar to the linear control counterpart, the performance in terms of noise measure attenuation is increased without unnecessarily deteriorating the time response of the closed-loop system.…”