Publications

This paper deals with the problem of leader-following consensus under a directed communication topology for a class of discrete-time multiagent systems with large delay sequences (LDSs). More specifically, to analyze the consensus problem of such a time-delay system with two different types of time-varying delays, new Lyapunov functionals are constructed. By imposing some constraints on the length and frequency of LDSs, a sufficient condition for ensuring the leader-following consensus is provided in the form of linear matrix inequalities (LMIs). A simulation example is provided to show the effectiveness of the proposed scheme.

This paper investigates the problem of robust reliable passive control for a class of uncertain stochastic switched time-delay systems with actuator failures. The multiple Lyapunov functions (MLFs) technique is exploited to derive a delay-dependent sufficient condition for the stochastic switched time-delay systems to be passive and exponentially stable under a state-based switching law. Moreover, the proposed approach is extended to investigate stochastic switched systems with structured uncertainties. Finally, two numerical examples are presented to illustrate the effectiveness of the proposed method.

This chapter aims to investigate the problem of adaptive sliding mode control (SMC) for a class of variable-order fractional (VOF) uncertain coupled systems. First, a novel VOF integral-type sliding surface, composed of nonlinear coupling terms, is designed with the aid of VOF calculus. This surface is crucial for effectively managing the complex dynamics of VOF systems. Second, based on graph theory, novel asymptotical stability criteria are derived for the resulting sliding mode dynamics, ensuring robust stability of the system. Moreover, the finite-time reachability of the predefined VOF integral-type sliding surface is ensured by designing a novel adaptive VOF controller, which adjusts the control parameters in real-time to maintain system performance. Finally, two numerical studies are presented to verify the validity and superiority of the proposed control strategy, demonstrating its effectiveness in handling the uncertainties and complexities inherent in VOF systems. These studies highlight the practical applicability and robustness of the adaptive SMC approach in achieving desired control objectives.

This paper concerns the robust control problems on the synchronization of a hyper-chaotic system with disturbance input. Using an appropriate Lyapunov function, we design the multi-dimensional and the single-dimensional robust H ∞ synchronization controllers in terms of linear matrix inequalities for the application in practical engineering. Corresponding theoretical derivations are given subsequently. Finally, some numerical simulations are provided to demonstrate the effectiveness of the proposed techniques.

Comfort, reliability, functionality performance which provide a longer life cycle requires thourogh understanding and analysis of the vibrations, this is a general rule for most of the static and dynamic functionality applications. Vibrations is an extremely important issue to consider when designing various systems. The hysteresis in the dampers is very important issue when characterizing a damper, it is a very complex phenomena but very important to consider. The hysteresis equations of Bouc-Wen, Lugre, and Dahl have been modeled and simulated in Matlab/Simulink. We have manipulated the different parameters in the models and analyzed their effects on the outcome. The hysteresis models of Bouc-Wen, Dahl and LuGre have been analyzed and compared analytically to really show the difference in the models. At last the Bouc-Wen model was implemented together with the SAS(Semi Active Suspension) system in the laboratory. The model parameters were tuned manually to try to fit the response of the system. In this paper a predefined methodology has been applied for determining the hysteresis loop parameters using the data collected for vibration analysis under predefined test specifications. The following data has been used later to regenerate the vibration signal, so on get as closer to the real signal. In the coming work, advanced method will be used to determine the exact parameters for the hysteresis loop as well as using the inverse hysteresis to improve the performace of the vibration suspension in the Semi Active Suspension system. The behavior of MR dampers can be presented with different mathematical models. The Bouc-Wen model was found to be model to both illustrate the MR damper and recreate the behavior of the SAS system.

This brief is concerned with the problem of a single-input pinning control design for reachability of Boolean networks (BNs). Specifically, the transition matrix of a BN is designed to steer the BN from an initial state to a desirable one. In addition, some nodes are selected as the pinning nodes by solving some logical matrix equations. Furthermore, a single-input pinning control algorithm is given. Eventually, a genetic regulatory network is provided to demonstrate the effectiveness and feasibility of the developed method.

This paper will entail the work of modeling, testing and verification of the Dielectric Electro Active Polymers (DEAP's) material. Whereby mathematical model will be derived to describe the statics and the dynamics of the DEAP's sheet, parameters of the models are determined using experimental/simulation results which will be used to verify and determine the precision of the derived dynamic model. The testing for finding the material properties is requested before doing the dynamic analysis, however this will not be addressed thoroughly in this paper. Both material characterization and dynamic analysis tests are performed using the developed testing rig specially designed for this purpose. The results of this study highlight the dependency of the material dynamics on the mechanical fixture of the material as well as the material creep properties, whereby the range of operation can be reduced to lower frequencies or expanded to higher frequencies when the mechanical fixture is designed for a certain application. The test results for the material shows an offset error between 0–20 Hz mainly because of the material creep but the error diverge after this range stimulated when exceeding the natural frequency of the system which lead to non stable state effecting the controllability of the actuated material, the offset error due to the creep is found to be eliminated using faster discharging circuits.

An active disturbance rejection station-keeping control scheme is derived and analyzed for station-keeping missions of spacecraft along a class of unstable periodic orbits near collinear libration points of the Sun-Earth system. It is an error driven, rather than model-based control law, essentially accounting for the independence of model accuracy and linearization. An extended state observer is designed to estimate the states in real time by setting an extended state, that is, the sum of unmodeled dynamic and external disturbance. This total disturbance is compensated by a nonlinear state error feedback controller based on the extended state observer. A nonlinear tracking differentiator is designed to obtain the velocity of the spacecraft since only position signals are available. In addition, the system contradiction between rapid response and overshoot can be effectively solved via arranging the transient process in tracking differentiator. Simulation results illustrate that the proposed method is adequate for station-keeping of unstable Halo orbits in the presence of system uncertainties, initial injection errors, solar radiation pressure, and perturbations of the eccentric nature of the Earth's orbit. It is also shown that the closed-loop control system performance is improved significantly using our method comparing with the general LQR method.

This paper reports on a study undertaken within the CEPT SE42 project team with the objective of evaluating the impact of adjacent-channel interference from TDD terminal stations (TSs) to FDD TSs in the 2.6 GHz band. The results confirm that the effects of TS-to-TS interference are very modest, even in high-density hot-spot scenarios, if the TS out-of-block emissions comply with a block-edge mask (BEM) baseline limit of -15.5 dBm/(5 MHz). In carrying out this analysis we have taken into account of interference experienced as a result of finite adjacent-channel interference ratios, inter-modulation products, and saturation effects.

A new saturation control technique is proposed to design multiobjective and robust anti‐windup controllers for linear systems with input saturations. Based on the characterization of saturation nonlinearities and modeling uncertainties via integral quadratic constraints (IQCs), this method considers a mixed H 2 / H ∞ performance indexes while maintaining dynamic constraints on the controller. The analysis and synthesis conditions are presented in terms of scaled linear matrix inequalities (LMIs). The proposed control algorithm can improve the performance of the input‐constrained system while also guaranteeing robustness with respect to the modeling uncertainties. Finally, a numerical example is given to illustrate the effectiveness of the developed techniques.

The necessary and sufficient condition of convex function is significant in nonlinear convex programming. This paper presents the identification of convex function on Riemannian manifold by use of Penot generalized directional derivative and the Clarke generalized gradient. This paper also presents a method for judging whether a point is the global minimum point in the inequality constraints. Our objective here is to extend the content and proof the necessary and sufficient condition of convex function to Riemannian manifolds.

The current paper describes an apparatus for full scale vehicle crash test experimentation. This apparatus is referred to as the Harp. In brief, the Harp may either accelerate a trolley which is impacted into a test vehicle or the test vehicle itself may be accelerated and impacted into an object such as a barrier, a pole or another vehicle. The trolley/vehicle is equipped with instruments which record the axial crushing force during the impact. At the impact site, high speed cameras and instrumentation record vital data during the crash.