双足机器人动态步行实时步态生成

针对双足机器人动态步行生成关节运动轨迹复杂问题,提出了一种简单直观的实时步态生成方案。建立了平面五杆双足机器人动力学模型,通过模仿人类步行主要运动特征并根据双足机器人动态步行双腿姿态变化的要求,将动态步行复杂任务分解为顺序执行的四个过程,在关节空间相对坐标系下设计了躯干运动模式、摆动腿和支撑腿动作及步行速度调整模式,结合当前步行控制结果反馈实时产生稳定的关节运动轨迹。仿真实验验证了该方法的有效性,简单易实现。     

The almost sure asymptotic stability and pth moment asymptotic stability of nonlinear stochastic delay differential systems with polynomial growth

In this paper, we discuss the asymptotic stability of nonlinear stochastic delay differential systems (SDDSs) whose coefficients obey the polynomial growth condition. By applying some novel techniques, we establish some easily verifiable conditions under which such SDDSs are almost surely asymptotically stable and pth moment asymptotically stable. A nontrivial example is provided to illustrate the effectiveness of our results. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Existence and stability of impulsive stochastic coupled systems in infinite dimensions

This paper considers the exponential stability of a class of infinite-dimensional impulsive stochastic coupled systems. With the help of generalized Itô's formula for the mild solution of infinite-dimensional systems, we avoid limiting the domain of the mild solution. Then we use the combination of the Lyapunov function and graph theory to construct the Lyapunov function of the systems; the criteria of $p$-th moment exponential stability are obtained, which is related to the average impulsive interval $T_a$ and the connectivity of impulsive stochastic systems. In addition, noting that the existence may be affected by impulsive effects and stochastic perturbations, using the graph theory and the principle of contraction mapping, we get the condition that guarantees the existence and uniqueness, which is also related to the structure of the networks. Finally, we consider the stability of impulsive stochastic coupled heat equations and neural networks with reaction diffusion and give some numerical simulations to verify the theoretical results.     

Improving accuracy of high-order discontinuous Galerkin method for time-domain electromagnetics on curvilinear domains

The paper discusses high-order geometrical mapping for handling curvilinear geometries in high-accuracy discontinuous Galerkin simulations for time-domain Maxwell problems. The proposed geometrical mapping is based on a quadratic representation of the curved boundary and on the adaptation of the nodal points inside each curved element. With high-order mapping, numerical fluxes along curved boundaries are computed much more accurately due to the accurate representation of the computational domain. Numerical experiments for two-dimensional and three-dimensional propagation problems demonstrate the applicability and benefits of the proposed high-order geometrical mapping for simulations involving curved domains.