车载音频系统的自动增益补偿设计

针对传统车载音频系统不能自动适应不断变化的车内声音环境的问题,设计了基于DSP技术的自动增益补偿。首先测试分析当前多媒体播放音量和车内噪声等关键因素对车内收听效果的影响,然后自动调节车载音频系统的增益和滤波器参数值,尤其对音量和响度进行动态补偿,最终确保在不断变化的车内环境中高音质的听觉享受。实车测试表明,该设计能有效地减少车内噪声影响,满足车内听觉频响特性。     

基于信息增量的弹道目标协同跟踪方法

针对反导传感器网络中弹道目标的协同跟踪问题,提出了一种基于信息增量的弹道目标协同跟踪方法。分析了多传感器对弹道目标的协同跟踪问题,并建立了自由段弹道目标分段匀加速模型。在此基础上,对自由段弹道目标跟踪过程中,利用跟踪滤波的协方差阵信息获得每个传感器对目标的信息增量,并以信息增量最大为准则选择传感器对弹道目标进行跟踪,从而实现对弹道目标的有效跟踪。仿真结果表明：所提的方法能够及时动态地选择性能最佳的传感器对弹道目标进行跟踪,提高弹道目标整体的跟踪性能,实现对弹道目标的协同跟踪。     

一种非线性反馈反步递推算法的线性弱化

为了解决反步递推算法应用于船舶航向控制中输出能量大且非线性部分难以对消的实际问题, 首先对原有的反步递推算法进行线性弱化, 然后利用正弦函数驱动的非线性反馈控制技术代替原有的线性误差反馈. 理论分析表明, 该算法能够保证控制效果相当或更优的前提下, 降低控制能量. 以“育龙” 轮为载体开展仿真实验, 结果表明所提出的新型非线性反馈控制律在鲁棒性、控制能量需求方面具有明显的优势.

     

Semi‐global output consensus of a group of linear systems in the presence of external disturbances and actuator saturation: An output regulation approach

This paper studies the problem of semi‐global leader‐following output consensus of a multi‐agent system. The output of each follower agent in the system, described by a same general linear system subject to external disturbances and actuator saturation, is to track the output of the leader, described by a linear system, which also generates disturbances as the exosystem does in the classical output regulation problem. Conditions on the agent dynamics are identified, under which a low‐gain feedback‐based linear state‐control algorithm is constructed for each follower agent such that the output consensus is achieved when the communication topology among the agents is a digraph containing no loop, and the leader is reachable from any follower agent. We also extend the results to the non‐identical disturbance case. In this case, conditions based on both the agent dynamics and the communication topology are identified, under which a low‐gain feedback‐based linear state‐control algorithm is constructed for each follower agent such that the leader‐following output consensus is achieved when the communication topology among the follower agents is a strongly connected and detailed balanced digraph, and the leader is a neighbor of at least one follower. In addition, under some further conditions on the agent dynamics, the control algorithm is adapted so as to achieve semi‐global leader‐following output consensus for a jointly connected undirected graph and the leader reachable from at least one follower. Copyright © 2015 John Wiley & Sons, Ltd.     

A Lyapunov‐based small‐gain approach on design of triggering conditions in event‐triggered control systems

This paper studies a Lyapunov‐based small‐gain approach on design of triggering conditions in event‐triggered control systems. The event‐triggered control closed‐loop system is formulated as a hybrid system model. Firstly, by viewing the event‐triggered control closed‐loop system as a feedback connection of two smaller hybrid subsystems, the Lyapunov‐based small‐gain theorems for hybrid systems are applied to design triggering conditions. Then, a new class of triggering condition, the safe, adjustable‐type triggering condition, is proposed to tune the parameters of triggering conditions by practical regulations. This is conducive to break the restriction of the conservation of theoretical results and improve the practicability of event‐triggered control strategy. Finally, a numerical example is given to illustrate the efficiency and the feasibility of the proposed results. Copyright © 2015 John Wiley & Sons, Ltd.     

Semi‐global and global containment control of multi‐agent systems with second‐order dynamics and input saturation

This paper considers both semi‐global and global containment control for a second‐order multi‐agent system that is composed by a network of identical harmonic oscillators or double integrators with multiple leaders and input saturation. A distributed low gain feedback algorithm is proposed to solve the semi‐global containment control problem for the network whose topology is directed and initial condition is taken from any a priori given bounded set. In particular, by using a parametric Lyapunov equation approach, M‐matrix properties and algebraic graph theory, an upper bound of the low gain parameter is estimated such that the low gain feedback matrix can be analytically determined without involving numerical computation. Furthermore, under the assumption that the induced subgraph formed by the followers is strongly connected and detail balanced, two linear feedback protocols are designed for coupled harmonic oscillators and coupled double integrators, respectively, to asymptotically achieve the global containment control of the network with any initial condition. Finally, numerical examples are given to illustrate the effectiveness of the theoretical results. Copyright © 2016 John Wiley & Sons, Ltd.     

Adaptive Tracking Control for Nonlinear Systems with a Class of Input Nonlinearities

An adaptive tracking control approach is presented for nonlinear systems with a class of input nonlinearities. A generalized model has been developed for a class of non‐smooth nonlinearities that include dead‐zone, backlash and ‘backlash‐like’ hysteresis. By using the developed model and Nussbaum‐gain technique, the problem of input nonlinearity is solved perfectly. The proposed method is available even when the designer is uncertain about the type of input nonlinearities mentioned above, and the knowledge on the bounds of these nonlinearity parameters is not required. Furthermore, it is proved that all closed‐loop signals are bounded and the tracking error converges to a small residual set asymptotically. Two simulation examples are provided to demonstrate the effectiveness of the proposed method.     

基于改进的MSR算法在软件视频会议系统上的应用

视频会议是一种应用广泛的会议方式,由于光照、视频采集设备品质、网络带宽等外界复杂因素的影响,常常导致视频会议视频图像质量下降。在多尺度Retinex滤波(MSR)算法的基础上,使用双边滤波获取原始图像的高低频信息,然后采用颜色约束方法和增益补偿方法增强经过双边滤波处理后的高频反射图像。通过主观体验和客观评价,改进算法增强了视频图像,同时保留了边缘细节,应用于软件视频会议系统,提高了视频图像的清晰度,改善了视觉效果。     

基于相关系数的决策树优化算法

通过分析ID3算法的基本原理及其多值偏向问题,提出了一种基于相关系数的决策树优化算法。首先通过引进相关系数对ID3算法进行改进,从而克服其多值偏向问题,然后运用数学中泰勒公式和麦克劳林公式的性质,对信息增益公式进行近似简化。通过具体数据的实例验证,说明优化后的ID3算法能够解决多值偏向问题。标准数据集UCI上的实验结果表明,在构建决策树的过程中,既提高了平均分类准确率,又降低了构建决策树的复杂度,从而还缩短了决策树的生成时间,当数据集中的样本数较大时,优化后的ID3算法的效率得到了明显的提高。     

Input‐output triggered control using ‐stability over finite horizons

This paper investigates stability of nonlinear control systems under intermittent information. Following recent results in the literature, we replace the traditional periodic paradigm, where the up‐to‐date information is transmitted and control laws are executed in a periodic fashion, with the event‐triggered paradigm. Building on the small gain theorem, we develop input–output triggered control algorithms yielding stable closed‐loop systems. In other words, based on the currently available (but outdated) measurements of the outputs and external inputs of a plant, a mechanism triggering when to obtain new measurements and update the control inputs is provided. Depending on the noise in the environment, the developed algorithm yields stable, asymptotically stable, and ‐stable (with bias) closed‐loop systems. Control loops are modeled as interconnections of hybrid systems for which novel results on ‐stability are presented. The prediction of a triggering event is achieved by employing ‐gains over a finite horizon. By resorting to convex programming, a method to compute ‐gains over a finite horizon is devised. Finally, our approach is successfully applied to a trajectory tracking problem for unicycles. Copyright © 2014 John Wiley & Sons, Ltd.