Trajectory tuning for the tracking problem of the underactuated mechanical systems: application to the PVTOL aircraft

The Planer vertical take-off and landing (PVTOL) aircraft is a typical example of an underactuated mechanical system and has a nonminimum-phase nature. When considering output tracking control, the Input/Output (I/O) linearization method is not appropriate since the stability of the internal dynamics is not guaranteed. Hauser et al. regarded this system as a slightly nonminimum-phase system which approximates to a minimum-phase one. Their control scheme yielded good results when the coupling factor was small, but the results were not acceptable when the coupling factor increased. In this article, we propose two approaches to improve the control performance. First, we consider the approximation error of Hauser's scheme as uncertainty, and apply the Linear Quadratic Regulator (LQR) method, which possesses robustness against uncertainty, to determine the stabilizing feedback coefficients. Second, from the fact that the tracking error is unavoidable, we use the “virtual reference trajectory” to design the tracking control law, and optimize this trajectory to reduce the tracking error between the “actual reference trajectory” and the “resulting trajectory”. This optimization also improves the control performance by choosing a suitable performance index. By using our approach, we achieve better performance even if the coupling factor is increased. We show these results by numerical simulation. This work was presented, in part, at the Seventh International Symposium on Artificial Life and Robotics, Oita, Japan, January 16–18, 2002     

一种基于M-JPEG的视频码流传输方案及其应用

针对现有的Internet通常不支持QoS的现象，提出了一种基于M－JPEG编码格式的自适应Internet视频码流传输方案，及其作为视频传输子系统在视频监控系统中的应用。     

Static Output Feedback Stabilization: An ILMI Approach

In this note, the static output feedback stabilization problem is addressed using the linear matrix inequality technique. A necessary and sufficient condition for static output feedback stabilizability for linear time-invariant systems is derived in the form of a matrix inequality. The extension of the result to H_∞ control is studied. An iterative LMI (ILMI) algorithm is proposed to compute the feedback gain. Numerical examples are employed to demonstrate the effectiveness and the convergence of the algorithm.     

柔性机器人的动力学建模及其控制*

本文首先综述了近年来在柔性机器人动力学建模方面所取得的进展，着重介绍了目前较常见的几种建模方法和模型，同时对柔性机器人的控制问题进行了评述，指出了今后研究的方向。     

Comparison between cellular automata and linear feedback shift registers based pseudo-random number generators

A detailed comparison between pseudo-random number generators (PRNGs) based on cellular automata (CA) and linear feedback shift registers (LFSRs) is presented in this paper. Various statistical tests have been applied in order to reveal the advantages and disadvantages of both approaches. Both LFSRs and hybrid additive cellular automata (HACA) produce satisfactory PRNGs. HACA operate at higher speeds than LFSRs with the same characteristic polynomials. Regarding the silicon area, direct comparisons between the two approaches cannot be made since it depends on the PRNG length. However, the inherent modularity of HACA reduces the silicon area occupied by them and, when long feedback paths are used, the silicon area occupied by LFSRs increases.     

液压电梯的单片机控制系统的设计与研究

介绍速度反馈式液压电梯的单片机控制系统。描述系统的组成和软件设计技术。该系统具有自动采集液压电梯轿厢运行数据、控制电梯运行过程、显示运行和调试参数及输出运行曲线等功能，并配置数据库。实用结果表明：这种单片机控制系统具有较优的动、静态控制性能、温度稳定性和较强的抗干扰能力。也非常适合于流体动力控制这一类系统使用。     

Disturbance Attenuation and Trajectory Tracking via a Reduced-order Output Feedback Controller for Robot Manipulators

This paper presents a solution to the problem of trajectory tracking with external disturbance attenuation in robotics systems via a reduced-order output feedback controller, without velocity measurement. The proposed control law ensures both semi-global asymptotic stability of the closed-loop system and external disturbance attenuation. The approach is based on the notion of the L₂-gain and requires to solve two algebraic Riccati inequalities. The proposed controller design is illustrated by a simulation example.     

Receding horizon control via Bolza-type optimization

This paper deals with the stabilization problem of nonlinear control systems. A variant of the receding horizon control method is proposed which is based on the solution of a certain Bolza problem. The stabilizing property of the method is proved in the case of Lipschitz continuous value function. This version of receding horizon scheme can be considered as a straightforward generalization of the so-called Fake Riccati Equation Technique for nonlinear constrained systems.     

一种基于最小二乘支持向量机的预测控制算法

针对工业过程中普遍存在的非线性被控对象，提出一种基于最小二乘支持向量机建模的预测控制算法．首先，用具有RBF核函数的LS-SVM离线建立被控对象的非线性模型；然后，在系统运行过程中，将离线模型在每一个采样周期关于当前采样点进行线性化，并用广义预测算法实现对被控系统的预测控制．仿真结果表明了该算法的有效性和优越性．     

Application of Feedback Linearization Method in Airplane Automatic Landing Control System

Summarizes the I/O feedback linearization about MIMO system, and applies it to nonlinear control equation of airplane. And also designs the tracing control laws for airplane longitudinal automatic landing control system.