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。     

输入饱和与姿态受限的四旋翼无人机反步姿态控制

本文针对四旋翼无人机研究了鲁棒反步姿态控制策略.由于四旋翼无人机结构复杂,其非线性数学模型难以精确建立,因此在控制器设计过程中需要综合考虑模型不确定性、未知外部干扰、输入饱和以及姿态受限等因素.针对模型中的不确定项,使用神经网络进行逼近;对于外部未知干扰,使用非线性干扰观测器进行补偿;使用双曲正切函数逼近饱和函数,解决输入饱和问题;同时使用界限Lyapunov函数设计控制器,确保姿态满足限制条件.最后,设计四旋翼无人机反步姿态控制器,并根据Lyapunov稳定性定理证明了闭环控制系统的有界稳定.仿真结果表明了所研究控制方法的有效性.     

车载PEPS低频自动标定系统

针对车载PEPS系统的低频发射场实测问题,设计了一套汽车电子设备电磁场自动标定系统.该系统控制三维机械臂实现自动行走将场强测试仪送到指定测试点并记录场强值,然后通过可视化技术实现了电磁场强的三维分布显示.设计的标定系统实现了对PEPS系统低频发射场高效而精确的标定,为深入研究PEPS系统电磁场分布特征奠定了基础.     

基于Qt4/VS2010平台的自动测试系统

主要研究Qt4和Microsoft Visual Studio 2010作为平台的自动测试工具的开发,分析软件需求和实现方法.针对测试软件所涉及的数据处理流程,详细介绍了实现方法和步骤,并对不同的功能模块加以分析,完成软件设计和开发,最终实现了提出的自动化测试的需求.     

基于环境激励的桥梁振动模态识别算法研究

在桥梁建造和维护过程中,需要对桥梁的振动模态进行在线、实时的分析,急需一种不需要人工激励进行快速模态分析的算法。通过研究自然激励技术NExT( Natural Excitation Technique)与自回归滑动平均模型ARMA( Auto￣Regressive and Moving Average Model),在常规的自然环境模态分析算法的基础上构造出一种快速求解NExT￣ARMA模型的算法进行桥梁模态识别。相比于传统的环境激励模态参数计算方法,该算法不但降低了传统算法的复杂度,而且采用了反馈的方式提高了计算精度。采用ANSYS建立有限元模型并搭建简易实验系统分别对该算法进行仿真验证和实验验证,验证结果表明,该算法能够有效地在自然激励下提取出桥梁结构的各阶模态,其中对前三阶固有频率的识别相对误差降到1％左右。     

The design and test of dual/triple‐mode bandpass filter based on temporal coupled‐mode theory

In this article, the design and test of both a K‐band dual‐mode bandpass filter (BPF) pair and a K‐band triple‐mode BPF are presented based on N‐mode temporal coupled‐mode theory (CMT). The expressions of transmission and reflection responses are analytically derived. All the parameters in the expressions have clear physical meanings and are easily optimized to reach the required filter performance. Aided by eigenmode simulations, concrete structures of the three integrated BPFs are designed and optimized to approach the calculated physical parameters. After the fabrications and measurements of the three BPFs, extended upper/lower stopband with high stopband rejections are achieved, and by increasing the number of resonant modes, improved frequency selectivity and better passband flatness are obtained. The analytical analysis well predicts the simulation and measurement results, which provides an efficient way for BPF designs. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:609–622, 2016.     

Gait Generation and Stabilization for Nearly Passive Dynamic Walking Using Auto‐distributed Impulses

We propose a state feedback control design via linearization for flexible walking on flat ground. First, we generate nearly passive limit cycles, being stable or not, using impulsive toe‐off actuations. The term ‘nearly passive’ means that the dynamics is completely passive almost everywhere except at the toe‐off moment. A feature of our gait generation method is that walking gaits are characterized only by amounts of supplied energy, and we observe that other variables, including input torques, are auto‐balanced via our method. After gait generation, we design a feedback controller considering robustness and input saturation. As a result, each limit cycle can be matched with its respective controller classified only by energy levels. We have verified that walking speeds monotonically increase by adding more energy, and the ankle joint plays a significant role in compass‐gait walking. Finally, instead of applying impulsive torques, we discuss a practical issue regarding realistic control inputs that ensure stable gait transitions as energy levels are elevated.     

Some results on disturbance attenuation for Hamiltonian systems via direct discrete‐time design

The disturbance attenuation and robust disturbance attenuation problems for Hamiltonian systems in the discrete‐time setting are considered and some new results are presented. The new results are derived utilizing the recently presented dissipativity equality obtained by adding the dissipation rate function to the classical dissipativity inequality. A selection of the dissipation rate function yields new results. These results include a condition on the dissipation structure of the system to achieve the desired disturbance attenuation level and gives direct construction of optimal control laws for any desired disturbance attenuation level. The results remove the need to solve Hamilton–Jacobi–Isaacs inequalities. Copyright © 2014 John Wiley & Sons, Ltd.     

On ADRC for non-minimum phase systems: canonical form selection and stability conditions

Active disturbance rejection control (ADRC), as proposed by Prof. Jingqing Han, reduces first the plant dynamics to its canonical form, normally in the form of cascade integrators, for which the standard controller can be employed to meet the design specifications. This paper concerns with the selection of the canonical form for non-minimum phase systems. In particular, it is shown that, by employing the well known controllable canonical form, the uncertainties of such systems can be divided into two terms in the state space model, one in the control channel and the other in the output channel. The necessary and sufficient condition is obtained for the stability of the closed-loop system with the proposed canonical form and ADRC. Also, by showing the necessity of the detectability of the extended system as well as certain information of the systemˉs “zeros”, we present the fundamental guidelines of design ADRC for non-minimum phase uncertain systems.     

Active disturbance rejection control: between the formulation in time and the understanding in frequency

With the rapid deployments of the active disturbance rejection control (ADRC) as a bonafide industrial technology in the background, this paper summarizes some recent results in the analysis of linear ADRC and offers explanations in the frequency response language with which practicing engineers are familiar. Critical to this endeavor is the concept of bandwidth, which has been used in a more general sense. It is this concept that can serve as the link between the otherwise opaque state space formulation of the ADRC and the command design considerations and concerns shared by practicing engineers. The remarkable characteristics of a simple linear ADRC was first shown in the frequency domain, followed by the corresponding analysis in time domain, where the relationship between the tracking error and the ADRC bandwidth is established. It is shown that such insight is only possible by using the method of solving linear differential equations, instead of the more traditional techniques such as the Lyapunov methods, which tend to be more conservative and difficult to grasp by engineers. The insight obtained from such analysis is further demonstrated in the simulation validation.