Enhancement in pneumatic positioning system using nonlinear gain constrained model predictive controller: experimental validation

The issues of inaccurate positioning control have made an industrial use of pneumatic actuator remains restricted to certain applications only. Non-compliance with system limits and properly control the operating system may also degrade the performance of pneumatic positioning systems. This study proposed a new approach to enhance pneumatic positioning system while considering the constraints of system. Firstly, a mathematical model that represented the pneumatic system was determined by system identification approach. Secondly, model predictive controller (MPC) was developed as a primary controller to control the pneumatic positioning system, which took into account the constraints of the system. Next, to enhance the performance of the overall system, nonlinear gain function was incorporated within the MPC algorithm. Finally, the performances were compared with other control methods such as constrained MPC (CMPC), proportional-integral (PI), and predictive functional control with observer (PFC-O). The validation based on real-time experimental results for 100 mm positioning control revealed that the incorporation of nonlinear gain within the MPC algorithm improved 21.03% and 2.69% of the speed response given by CMPC and PFC-O, and reduced 100% of the overshoot given by CMPC and PI controller; thus, providing fast and accurate pneumatic positioning control system.

Entanglement and Photon Anti-Bunching in Coupled Non-Degenerate Parametric Oscillators

We analytically and numerically show that the Hillery-Zubairy’s entanglement criterion is satisfied both below and above the threshold of coupled non-degenerate optical parametric oscillators (NOPOs) with strong nonlinear gain saturation and dissipative linear coupling. We investigated two cases: for large pump mode dissipation, below-threshold entanglement is possible only when the parametric interaction has an enough detuning among the signal, idler, and pump photon modes. On the other hand, for a large dissipative coupling, below-threshold entanglement is possible even when there is no detuning in the parametric interaction. In both cases, a non-Gaussian state entanglement criterion is satisfied even at the threshold. Recent progress in nano-photonic devices might make it possible to experimentally demonstrate this phase transition in a coherent XY machine with quantum correlations.

Transmission stability of chirped dark vector quasi-solitons in birefringent fiber system with nonlinear gain

In this article, we consider the coupled Ginzburg–Landau equation with variable coefficients including the nonlinear gain and obtain the exact solutions of chirped dark vector quasi-solitons via the ansatz method. Next, the propagation of chirped dark vector quasi-solitons is discussed to verify whether they can be transmitted stably in the birefringent optical fiber system. The numerical simulation shows that this can be achieved. We deeply add the small perturbation to the transmission of dark vector quasi-solitons to make the results above more general. The results further prove the correctness of our solutions.