Barrier function based finite-time tracking control for a class of uncertain nonlinear systems with input saturation

In this article, a novel robust finite-time tracking control scheme is proposed for a class of uncertain nonlinear systems subject to the model uncertainty, external disturbance, and input saturation. A barrier function based disturbance observer (BFDO) with finite-time convergence performance is developed to estimate the non-smooth nonlinear compound disturbance, which includes the uncertainty, disturbance of system and input saturation. In addition, an adaptive continuous nonsingular terminal sliding mode controller, based on the barrier function and the estimate of the BFDO is developed. The Lyapunov stability and finite-time convergence of the proposed control scheme are proved. The effectiveness and performance advantage of the proposed control scheme is demonstrated by numerical simulations and comparison with existing works.     

4G/5G网络融合演进探析

随着5G SA网络的商用部署,5G与4G协同演进是运营商十分关心的迫切问题。首先,分析了EPC网络为何将长期存在,提出5GC与EPC融合组网是移动核心网的中长期架构,随后,重点分析EPC网络如何与5GC网络协同演进发展,探讨了MME、DRA等EPC网元的演进路径,同时考虑了后续EPC网络的部署形态,为未来的移动网络演进做出有益的探讨。     

云网融合探索新时代文明实践信息化建设新方向

华数云新时代文明实践中心云平台,综合应用云计算、大数据、移动互联网和物联网以及广电网络等新一代信息技术,发挥华数云云网融合的能力优势,结合广电传播能力,创建新时代文明实践中心、所、站3级组织架构工作平台,实现"思想引导、文化引育、价值引领、网络为民"功能。     

Iterative computational approach to the solution of the Hamilton-Jacobi-Bellman-Isaacs equation in nonlinear optimal control

In this paper, iterative or successive approximation methods for the Hamilton-Jacobi-Bellman-Isaacs equations (HJBIEs) arising in both deterministic and stochastic optimal control for affine nonlinear systems are developed. Convergence of the methods are established under fairly mild assumptions, and examples are solved to demonstrate the effectiveness of the methods. However, the results presented in the paper are preliminary, and do not yet imply in anyway that the solutions computed will be stabilizing. More improvements and experimentation will be required before a satisfactory algorithm is developed.     

Nonlinear robust control of a quadrotor helicopter with finite time convergence

In this paper, the control problem for a quadrotor helicopter which is subjected to modeling uncertainties and unknown external disturbance is investigated. A new nonlinear robust control strategy is proposed. First, a nonlinear complementary filter is developed to fuse the raw data from the onboard barometer and the accelerometer to decrease the negative effects from the noise associated with the low-cost onboard sensors Then the adaptive super-twisting methodology is combined with a backstepping method to formulate the nonlinear robust controller for the quadrotor''s attitude angles and the altitude position. Lyapunov based stability analysis shows that finite time convergence is ensured for the closed-loop operation of the quadrotor''s roll angle, pitch angle, row angle and the altitude position. Real-time flight experimental results, which are performed on a quadrotor flight testbed, are included to demonstrate the good control performance of the proposed control methodology.     

具有Levy变异和精英自适应竞争机制的蚁狮优化算法

针对蚁狮优化算法易陷入局部最优、收敛速度慢的缺点,本文提出一种具有Levy变异和精英自适应竞争机制的蚁狮优化算法。利用服从Levy分布的随机数对种群较差个体进行变异,可改善种群多样性提高算法的全局搜索能力;精英自适应竞争机制使得多个精英并行带领种群寻优,提高了算法的收敛速度,为避免较大计算量,并行竞争的精英个数会随着寻优代数增加而减少。同多个改进算法进行比较,结果表明本文所提算法具有更好的寻优精度和收敛速度。最后将本文改进算法应用于硅单晶热场温度模型的参数辨识,仿真结果说明该算法具有较好的参数辨识能力。     

An infeasible active-set QP-free algorithm for general nonlinear programming

We propose an infeasible active set QP-free algorithm for general constrained optimization in this paper. It starts from an arbitrary initial point. At each iteration, only two or three reduced linear equations with the same coefficients are solved to obtain the search direction. To determine the working set, the method makes use of multipliers from the last iteration, eliminating the need to compute a new estimate, and no additional linear systems are solved to select linear independent constraint gradients. The infeasibility measure and the objective function value are controlled separately by the filter technique. Without the positive definiteness assumption on the Hessian estimate, the sequence generated by the algorithm still globally converges to a Karush-Kuhn-Tucker point. And the algorithm obtains superlinear convergence without the strict complementarity. At last, preliminary numerical results are reported.