Guoyuan Qi

FOUR-WING ATTRACTORS: FROM PSEUDO TO REAL

Some basic dynamical behaviors and the compound structure of a new four-dimensional autonomous chaotic system with cubic nonlinearities are investigated. A four-wing chaotic attractor is observed n...

Chaotic Characteristics Analysis and Circuit Implementation for a Fractional-Order System

Based on fractional transfer function approximation in frequency domain, the paper firstly discusses the fractional form of a four-wing autonomous integral-order chaotic system, and finds some chaotic attractors in the different orders of the fractional-order system. The chaotic attractors can be found when the order of the fractional-order system is varied from 1.5 to 2.7, especially in the fractional-order system of the order as low as 2.7, and various chaotic behaviors occur when varying four different system parameters. Some bifurcation diagrams and phase portraits including the four-wing chaotic attractors, the two-wing chaotic attractors, and some periodic orbits are given to verify the chaotic behaviors of the fractional-order system. Then, based on the method of topological horseshoe analysis adopted in many integer-order chaotic systems, a topological horseshoe is found to prove the existence of chaos in the fractional-order system of the order as low as 2.7. At last, an analog circuit is designed to confirm the chaotic dynamics of fractional-order system.

A 3-D four-wing attractor and its analysis

In this paper, several three dimensional (3-D) four-wing smooth quadratic autonomous chaotic systems are analyzed. It is shown that these systems have a number of similar features. A new 3-D continuous autonomous system is proposed based on these features. The new system can generate a four-wing chaotic attractor with less terms in the system equations. Several basic properties of the new system is analyzed by means of Lyapunov exponents, bifurcation diagrams and Poincare maps. Phase diagrams show that the equilibria are related to the existence of multiple wings.

Difference Histograms: A new tool for time series analysis applied to bearing fault diagnosis

A powerful tool for bearing time series feature extraction and classification is introduced that is computationally inexpensive, easy to implement and suitable for real-time applications. In this paper the proposed technique is applied to two rolling element bearing time series classification problems and shown that in some cases no data pre-processing, artificial neural network or nearest neighbour approaches are required. From the results obtained it is clear that for the specific applications considered, the proposed method performed as well as or better than alternative approaches based on conventional feature extraction.

GENERATION OF AN EIGHT-WING CHAOTIC ATTRACTOR FROM QI 3-D FOUR-WING CHAOTIC SYSTEM

This paper presents an eight-wing chaotic attractor by replacing a constant parameter with a switch function in Qi four-wing 3-D chaotic system. The eight-wing chaotic attractor has more complicated topological structures and dynamics than the original one. Some basic dynamical behaviors and the compound structure of the proposed 3-D system are investigated. Poincare-map analysis shows that the system has an extremely rich dynamics. The physical existence of the eight-wing chaotic attractor is verified by an electronic circuit FPGA.

Output feedback predictive control for uncertain non-linear switched systems

In this paper, a hybrid predictive controller is proposed for a class of uncertain non-linear switched system with input constraints and unavailable state measurements. The main idea is to design a bounded non-linear controller and a predictive controller for each subsystem using Lyapunov functions and state observers, also a suitable switched law to stabilise the closed-loop subsystem, and to provide an explicitly characterised set of initial condition. For the whole switched system, based on the state estimates, a suitable switched law is designed to ensure the whole closed-loop’s stability. The simulation results for a chemical process show the validity of the controller proposed in this paper.

Fully connected particle swarm optimizer

In this article, a new model for particle swarm optimization (PSO) is proposed. In this model, each particles behaviour is influenced by the best experience among its neighbours, its own best experience and all its components. The influence among different components of particles is implemented by the online training of a multi-input single-output back propagation (BP) neural network. The inputs and outputs of the BP neural network are the particle position and its tendency to the best position, respectively. Therefore, the new structured PSO model is called a fully connected particle swarm optimizer (FCPSO). Simulation results and comparisons with exiting PSOs demonstrate that the proposed FCPSO effectively enhances the search efficiency and improves the search quality.

Chaotic particle swarm optimization

A new particle swarm optimization (PSO) algorithm with has a chaotic neural network structure, is proposed. The structure is similar to the Hopfield neural network with transient chaos, and has an improved ability to search for globally optimal solution and does not suffer from problems of premature convergence. The presented PSO model is discrete-time discrete-state. The bifurcation diagram of a particle shows that it converges to a stable fixed point from a strange attractor, guaranteeing system convergence.

Motion control and stabilization of a Skid-Steering Mobile Robot

In this paper, motion control and stabilization of a 4-Wheel Skid-Steering Mobile Robot (4WSSMR) are studied. A ratio controller which has been successfully applied in the chemical industry is designed to limit the vehicle lateral skid. Motion stability is guaranteed by generating an appropriate steering action (driving bias in left and right wheels) according to the states of the vehicle. A model free High Order Differential Feedback Controller (HODFC) cooperates with the ratio controller for motion control. In the proposed model-free scheme vehicle states used by the ratio controller and HODFC are estimated by high order differential (HOD) observer. Different road surface scenarios with varying frictional coefficients are designed to test performance and the ability to reject disturbances and noise. Trajectory tracking simulation results show that the proposed is robust to uncertainties and performs well even if some parameters are unknown.

Analysis of a new hyperchaotic system with two large positive Lyapunov exponents

The Qi hyperchaotic system is further investigated for some basic properties. Both 1-D and 2-D Lyapunov exponents (LE) spectra show that the system has two large positive LEs over very large parameter regions. A histogram shows the stochastic properties to be very similar to that of Gaussian white noise, verifying and indicating its great potential for some relevant engineering applications such as secure communications.