Terminal Sliding Mode Control with a Novel Reaching Law and Sliding Mode Disturbance Observer for Inertial Stabilization Imaging Sensor

High-performance control of inertial stabilization imaging sensors (ISISs) is always challenging because of the complex nonlinearities induced by friction, mass imbalance, and external disturbances. To overcome this problem, a terminal sliding mode controller (TSMC) based on a novel exponential reaching law (NERL) method with a high-order terminal sliding mode observer (HOTSMO) is suggested. First, the TSMC based on NERL is adopted to improve system performance. The NERL incorporates the power term and switching gain term of the system state variables into the conventional exponential reaching law, and the convergent speed of the TSMC is accelerated. Then, an HOTSMO is designed, which considers the speed and lumped disturbances of the system as the observation object. The estimated disturbance is then provided as a compensation for the controller, which enhances the disturbance rejection ability of the system. Comparative simulation and experimental results show that the proposed method achieves the best tracking performance and the strongest robustness than PID and the traditional TSMC methods.

Collision dynamics of two bright solitons in growth Bose–Einstein condensates with tunable interactions

By using the split-step fast Fourier transform (SSFFT) method, we numerically study the collision properties between two bright solitons in the growth Bose–Einstein condensates (BECs) with different interaction strengths under a harmonic potential. It is shown that the soliton’s collision property of the condensates can be controlled by adjusting the gain term, the initial position and the interaction strength between atoms. The number of collisions of the two bright solitons decreases first, then increases, with increasing the values of the gain term. As the initial distance between solitons increases, the number of collisions between the two bright solitons is reduced, and the first collision time is also postponed. The increase in interaction strength between atoms delays the collision time of the two bright solitons. Meanwhile, a critical interaction strength between atoms is found, the amplitude of the soliton’s first collision peak increases slowly when the interaction strength is less than the critical value, but the amplitude increases sharply when the interaction strength is more than the critical value.

A New Model for Constant Fuel Utilization and Constant Fuel Flow in Fuel Cells

This paper presents a new model of fuel cells for two different modes of operation: constant fuel utilization control (constant stoichiometry condition) and constant fuel flow control (constant flow rate condition). The model solves the long-standing problem of mixing reversible and irreversible potentials (equilibrium and non-equilibrium states) in the Nernst voltage expression. Specifically, a Nernstian gain term is introduced for the constant fuel utilization condition, and it is shown that the Nernstian gain is an irreversibility in the computation of the output voltage of the fuel cell. A Nernstian loss term accounts for an irreversibility for the constant fuel flow operation. Simulation results are presented. The model has been validated against experimental data from the literature.

Effect of the Random Field on the Dynamics of Pulsating, Erupting, and Creeping Solitons in the Cubic-Quintic Complex Ginzburg-Landau Equation

It is shown that the dynamics of pulsating, erupting, and creeping (PEC) solitons obtained from the one-dimensional cubic-quintic complex Ginzburg-Landau equation can be drastically modified in the presence of a random background field. It is found that, when the random field is applied to a pulselike initial profile, multiple soliton trains are formed for the parameters of the pulsating and erupting solitons. Furthermore, as the strength of the gain term increases, the multiple pulsating or erupting solitons transform into fixed-shape stable solitons. This may be important for a practical use such as to generate stable femtosecond pulses. For the case of creeping soliton parameters, the presence of the random field does not generate multiple solitons, however, it induces a rapidly twisting or traveling soliton with a fixed-shape, of which stability can be also controlled by the gain term. - PACS numbers: 42.65.Tg, 03.40.Kf, 05.70.Ln, 47.20.Ky.

Dynamics of Pulsating, Erupting, and Creeping Solitons in the Cubic- Quintic Complex Ginzburg-Landau Equation under the Modulated Field

It is shown that the dynamics of the pulsating, erupting, and creeping (PEC) solitons in the one-dimensional cubic-quintic complex Ginzburg-Landau equation can be drastically modified in the presence of a modulated field. We first perform the linear instability analysis of continuous-wave (CW) and obtain the gain by the modulational instability (MI). It is found that the CW states applied by the weakly modulated field always transform into fronts for the parameters of the PEC solitons. We then show that, when the modulated field is applied to the pulse-like initial profile, multiple solitons are formed for the parameters of the pulsating and erupting solitons. Furthermore, as the strength of the gain term increases, the multiple pulsating or erupting solitons transform into fixedshape stable solitons. This may be important for a practical use such as to generate multiple stable femtosecond pulses. For the case of creeping soliton parameters, the presence of a modulated field does not generate multiple solitons, however, the initial profile transforms into an irregularly pulsating soliton or evolves into a fixed-shape soliton as the strength of the gain term is increased. - PACS numbers: 42.65.Tg, 03.40.Kf, 05.70.Ln, 47.20.Ky

Dynamic Anti-Integrator-Windup Controller Design for Linear Systems With Actuator Saturation

The present paper is concerned with the design of dynamic anti-integrator-windup controllers for critically stable linear systems with a single pole at the origin. The constant gain term in the conventional anti-windup controller is extended to have dynamics represented by a transfer function. The proposed dynamic anti-windup compensator is similar to the one based on co-prime factorization of the plant. The overall controller includes an internal model for constant signals and achieves regulation for constant disturbance and reference inputs as long as the asymptotic control input stays within the saturation limits. The effectiveness of the proposed method is demonstrated on a one-link flexible arm through simulations and experiments.