2,312 publications from this institution
A higher-order approximation analytical solution for a current-carrying ion sheath is automatically derived in computer by decomposition method. Chaos behaviors in the system driven by an external periodic oscillation are controlled using feedback control strategy. Its effectiveness is verified by numerical simulations.
ABSTRACT This paper presents the design and development of a bionic blind‐guiding robot based on a wheeled‐legged foldable structure, aimed at assisting visually impaired individuals in navigating complex environments. The robot integrates the advantages of both legged and wheeled robots, combining high mobility and environmental adaptability with improved movement efficiency and stability. The mechanical design incorporates a foldable structure inspired by guide dogs, enabling the robot to navigate uneven terrain, climb stairs, and curl up under furniture. A comprehensive kinematic and dynamic model is established to facilitate precise control of the robot's motion. The control system employs a Virtual Model Control approach, with force distribution optimized using Quadratic Programming to ensure stable locomotion. The robot features multiple motion modes, including legged, wheeled, and wheeled‐legged cooperative walking, allowing for flexible adaptation to different terrains. Human–robot interaction is enhanced through a guide saddle connection, providing tactile feedback and control options for the user. Experimental results demonstrate the robot's ability to maintain stability under varying traction forces and its effectiveness in guiding blind individuals through indoor and outdoor environments. The proposed design offers a promising solution for improving the mobility and independence of visually impaired individuals.
This brief proposes a unified approach for generating chaos in n-dimensional continuous-time affine systems, with n/spl ges/3, based on the normal form of chaotic systems and nonlinear control theory. A feedback-control law is designed to make a feedback linearizable system topologically conjugate to a reference chaotic system, thereby forcing the given system to become chaotic. Furthermore, if the relative degree of a given feedback unlinearizable system is not less than three and the corresponding internal dynamics of the system is input-to-state stable, then a feedback-control law can still be designed to drive a subsystem of such a controlled system topologically conjugate to a reference chaotic system, thereby generating chaos from that subsystem.
No abstract is provided for this article.
No abstract is provided for this article.
No abstract is provided for this article.
This chapter reviews various types of conventional and fuzzy proportional-integral-derivative (PID) controllers, and their new developments in achieving autotuning—adaptive and robust capabilities. The chapter emphasizes two types of PID controllers: fuzzy PID controllers and conventional PID controllers. Both these controllers are not exactly comparable—in fact, it is generally impossible to have exactly the same conditions for a fair comparison of these controllers. As long as the fuzzy PID controllers work for some control problems for some systems that the conventional ones can't work out or don't work out so well, they have their own merits. Comparisons are actually difficult: fuzzy PID controllers have been developed for only five years or so and hence are certainly not as mature as the conventional ones that have a more than fifty-year history. There are still many drawbacks, weak-points, and technical problems inherent with various fuzzy PID-type of controllers, which is the very challenge that calls for further effort and endeavor from the research and engineering communities.
A novel distributed consensus protocol, where only causal sampled position data are used, is firstly designed for second-order linear multi-agent systems with a directed communication topology. In this context, a necessary and sufficient condition depending upon the coupling gains, sampling period, and spectrum of the Laplacian matrix, is established for achieving consensus. It is revealed that second-order consensus in such a multi-agent system cannot be reached without using past sampled position data. It is also found that a relatively small sampling period does not necessarily improve the consensus performance. Then, a delay-induced consensus protocol is proposed based on sampled position data and with the help of time delay. It is found that consensus under this designed protocol cannot be reached in the absence of time delay. More interestingly, the time delay should have both lower and upper bounds in order to achieve consensus. Finally, the effectiveness of the theoretical results is demonstrated through numerical simulations.
A new approach for generating n-scroll attractors is introduced. It is demonstrated that n-scroll attractors can be generated using a simple sine or cosine function. A guideline is given so that a different number of scrolls can be designed easily by modifying two variables in the function. An electronic circuit is also designed for the implementation and the observation of a 9-scroll attractor is reported for the first time.
Professor Oleksandr M. Sharkovsky (December 7, 1936–November 21, 2022) was an honorary editorial board member of the International Journal of Bifurcation and Chaos. He left to the scientific world a famous Sharkovsky theorem established in his 1964 paper "Coexistence of Cycles of a Continuous Map of the Line into Itself," which laid the foundation of a new branch in the theory of dynamical systems — combinatorial dynamics. His contributions also include the Sharkovsky ordering, Sharkovsky space, Sharkovsky set, Sharkovsky stratification, and maximum period in the sense of Sharkovsky, among others. Professor Sharkovsky will be remembered forever.
This article analyzes the problem of the sliding-mode control (SMC) design for discrete-time piecewise nonhomogeneous Markov jump nonlinear systems (MJNSs) subject to an external disturbance with time-varying transition probabilities (TPs). A discrete-time asynchronous integral sliding surface is constructed, which yields matched-nonlinearity-free sliding-mode dynamics (SMDs). Then, by using the mode-dependent Lyapunov function technique, a sufficient condition is established for ensuring the stochastic stability of SMD with extended dissipation. The solution to designing controller gains is obtained. Moreover, an SMC law and an adaptive law are, respectively, derived for driving the system trajectories to move into a predetermined sliding-mode region with specified precision. Finally, the feasibility and effectiveness of the new design are verified and demonstrated by a simulation example.
Complex networks such as the Internet, WWW, transportation networks, power grids, biological neural networks, and scientific cooperation networks of all kinds provide challenges for future technological development. The first systematic presentation of dynamical evolving networks, with many up-to-date applications and homework projects to enhance study The authors are all very active and well-known in the rapidly evolving field of complex networks Complex networks are becoming an increasingly important area of research Presented in a logical, constructive style, from basic through to complex, examining algorithms, through to construct networks and research challenges of the future
