A novel adaptive inverse control (AIC) scheme is presented to facilitate on-line controller design of unknown nonlinear dynamic systems. The scheme is based on a control oriented model known as the U-model. The use of U-model alleviates the computational complexity of on-line nonlinear controller design that arises when using other modelling frame works such as NARMAX model. The effectiveness of the proposed scheme is illustrated by utilizing a laboratory scale nonlinear heating process as a test system.
We have proposed a novel 2 × 2 optical switch using multimode interference (MMI) coupler. This switch comprises four arms, located between two MMI couplers, and works by controlling a phase shifter, situated in each arm. Compared with conventional Mach-Zehnder type of optical switches, BPM simulation of this device predicted a high tolerance to fabrication errors. We fabricated the device with silica waveguides, and confirmed that it functioned with an insertion loss of 4.1dB and an extinction ratio of about 20dB.
We have developed novel device architecture of comb-driven double-gimbal XY-stage of high fill-factor (stage area / chip size), which has been realized for the first time by topologically separating the actuator elements in two layers: all the electrical parts (electrodes and interconnections) are in the Silicon-on-Insulator (SOI) layer, while the mechanical parts (suspensions, frame, and XY-stage) are in the substrate. Thanks to the new layered structures, the overall footprint of the actuator has been made small. The XY-stage moved 19µm in the X and the Y direction independently, and also in the diagonal direction.