Perturbation wavelet neural sliding mode position control for a voice coil motor driver

To cope with the nonlinear electro-magneto-mechanical characteristics, this paper proposes a perturbation wavelet neural sliding mode position control (PWSPC) system for a voice coil motor (VCM) driver. A perturbed wavelet neural network (PWNN) approximator is used to online approximate the unknown nonlinear term in the VCM system dynamics. The PWNN approximator uses perturbed wavelet functions to handle the rules uncertainties like interval type-2 fuzzy sets. The structure learning ability enables the PWNN approximator to evolve its structure online. Further, the parameter learning laws and stability analysis are derived in the sense of Lyapunov function; thus, the parameter convergence and system stability can be guaranteed. Finally, the experimental results verify that the proposed PWSPC system can achieve favorable control performance such as good disturbance rejection and good tracking accuracy.

     

微型直线旋转音圈电机的设计与分析

针对光电子封装设备对高精度、小体积、多维运动电机的需求,设计了一种微型单定子直线旋转两自由度音圈电机.介绍了电机的结构特点和运行原理,以输出推力和转矩特性为优化目标,利用有限元仿真对其结构参数进行了优化.根据优化的结构参数制造样机进行实验,实验结果表明:电机输出推力、扭矩幅值大,推力波动、扭矩波动在0.5％以下,验证了电机设计和优化仿真的有效性.     

抗语音分组丢失的自适应传输调整算法的实现

为提高语音的传输质量,减少语音分组因网络状况恶化造成的丢失现象,在研究实时语音传输技术的基础上,提出了一种抗语音分组丢失的自适应传输调整算法.通过量化接收端反馈回发送端的语音分组丢失率等信息来判断网络状态,并通过改进AIMD(和式增加乘积减少)拥塞控制算法来自适应地随网络状态调整语音的传输速率,以此来达到抗语音分组丢失的效果.通过自行搭建拓扑结构的网络环境,对算法进行了测试分析,验证了该算法的有效性.     

On-line constructive fuzzy sliding-mode control for voice coil motors

In this paper, a voice coil motor (VCM) featuring fast dynamic performance and high position repeatability is developed. To achieve robust VCM control performance under different operating conditions, an on-line constructive fuzzy sliding-mode control (OCFSC) system, which comprises of a main controller and an exponential compensator, is proposed. In the main controller, a fuzzy observer is used to on-line approximate the unknown nonlinear term in the system dynamics with on-line structure learning and parameter learning using a gradient descent algorithm. According to the structure learning mechanism, the fuzzy observer can either increase or decrease the number of fuzzy rules based on tracking performance. The exponential compensator is applied to ensure the system stability with a nonlinear exponential reaching law. Thus, the chattering signal can be alleviated and the convergence of tracking error can be speed up. Finally, the experimental results show that not only the OCFSC system can achieve good position tracking accuracy but also the structure learning ability enables the fuzzy observer to evolve its structure on-line.     

针对机动车驾驶员的人脸检测方法

为了正确检测人脸区域、提高驾驶室内光照不足情况下人脸检测与定位方法的准确性和实时性,采用了肤色聚类的人脸检测方法,利用肤色聚类性将彩色图像分割成皮肤区和非皮肤区。同时,提出一种基于多尺度Retinex算法的改进算法,其能够在人脸检测之前对图像进行光照补偿处理。将改进后的算法应用到新建立的人脸图像库中进行仿真实验,并与传统的肤色聚类人脸检测方法进行对比,其正确率提高了4.7%。实验结果表明:改进后的肤色聚类人脸检测算法可实现对不同光照变化和旋转角度的人脸进行检测,且具有很强的实用价值。     

语音PCM的Huffman编码研究与实现

传统的模拟语音PCM采用等长折叠二进制编码,其数码率较高,传输和处理所需系统资源较大。文章从语音信号抽样值的概率分布情况出发,在PCM编码的非均匀量化基础上,对13折线A律压扩特性采用变长编码,使信源的熵冗余得以减小,实现了语音MOS值不变情况下的压缩编码,同时,又运用EDA技术对压缩电路进行了基于CPLD的硬件设计。     

Statistical voice activity detection using low-variance spectrum estimation and an adaptive threshold

Traditionally, voice activity detection algorithms are based on any combination of general speech properties such as temporal energy variations, periodicity, and spectrum. This paper describes a novel statistical method for voice activity detection using a signal-to-noise ratio measure. The method employs a low-variance spectrum estimate and determines an optimal threshold based on the estimated noise statistics. A possible implementation is presented and evaluated over a large test set and compared to current modern standardized algorithms. The evaluations indicate promising results with the proposed scheme being comparable or favorable over the whole test set.     

Effects of voice technology on test track driving performance: implications for driver distraction

This work compares the degradation in driving performance associated with secondary tasks performed with voice-based and visual/manual interfaces, including radio tuning, phone dialing, and more complex tasks involving a sequence of interactions with an in-vehicle computer system. Twenty-one participants drove an instrumented vehicle while performing a combination of car-following, peripheral target detection, and secondary tasks on a closed test track. Drivers compensated for increased task demands associated with secondary tasks by increasing their following distance. Performing secondary tasks also resulted in significant decrements to vehicle control, target detection, and car-following performance. The voice-based interface helped reduce the distracting effects of secondary task performance. Modest improvements were observed for measures of vehicle control and target detection but not for car following. The results indicated that performing in-vehicle tasks required diversion of both peripheral (visual and manual) and attentional (cognitive) resources from driving. The voice-based interface reduced the peripheral impairment but did not appreciably reduce the attentional impairment. Actual or potential applications of this research include improvements to the design of invehicle information systems and the development of evaluation protocols to assess their distraction potential.     

高性能步进电动机细分驱动器的设计

本文设计了一种适合三相反应式步进电动机的高性能细分驱动器,在功率驱动中采用了大功率VMOS器件,在细分环形分配器设计中采用了两片GAL,使整个电路具有较高的运行性能,开关迅速,功耗小,体积较小,可靠性较高.     

两相混合式步进电机细分驱动器研制

讨论了步进电机的细分驱动原理以及数字PI控制策略。介绍了一种基于数字信号处理器(DSP)的两相混合式步进电机细分驱动器的软硬件结构,并给出了实际运行的电机相电流波形。通过采用电压补偿、电流负反馈以及数字PI调节,对步进电机相电流进行"阶梯化"正弦波控制,使步进电机相电流接近正弦波,改善了步进电机的运行工况。     

利用定时器中断实现CH452键盘驱动

针对键盘扫描控制芯片CH452和实时嵌入式系统的特点,提出了一种实现CH452键盘驱动的方法.在键盘中断服务程序中启动定时器中断,通过定时器中断服务程序产生读取CH452按键代码所用到的同步串行通信的时钟信号,同时完成数据信号的接收与发送.在由S3C2410和windowsCE.NET构成的实时嵌入式系统中用该方法实现了CH452键盘驱动.按键测试的结果和由示波器抓拍到的波形都表明,该方法能够满足系统对按键响应实时性和可靠性的要求.     

一种低压低功耗共源共栅带隙基准电压源的实现

提出了一种低压低功耗的带隙基准电压源电路,设计基于0.5μm2P3M BiCMOS Process,并使用了低压共源共栅电流镜结构减少了对电源电压的依赖,消除了精度与余度之间的矛盾,并用HL50S-S3.1S.lib库文件用HSPICE进行了仿真,其电源抑制比PSRR大约为-78.9dB。     

An event-driven simulation method for motor driver in virtual machine tool system

In this paper, an event-driven simulation method is proposed for the motor driver in a virtual machine tool system (VMT), of which simulation speed is always a puzzle. This method utilizes a set of pre-defined events to trigger the execution of simulator in a non-deterministic manner and at the most efficient moment. Comparing to the conventional time domain simulation method, it dramatically reduces the CPU time consumption without losing simulation accuracy, therefore it improves the simulation efficiency. The effectiveness of this method is verified through a PMSM (Permanent Magnet Synchronous Motor) motor driver model in studying Servo/Mechanical interaction within a VMT.     

超声电机测控系统的一种实现方法

设计了一套基于微机的超声电机速度和位置测试与控制系统.该系统解决了超声电机长时间工作时由于压电陶瓷特性的改变导致电机速度不稳定问题,采用PI算法的闭环控制时,电机速度可以稳定在3%之内.位置控制实验结果表明:采用模糊推理 PI控制器对电机进行位置精密伺服控制是完全可行的,精度可以达到0.09°.     

A high-gain adaptive observer for detecting Li-ion battery terminal voltage collapse

We use a high-gain adaptive observer and a trend filtering algorithm to detect early stages that lead to terminal voltage collapses in Li-ion batteries. This approach allows accurate detection without having sophisticated battery models. Theoretical analysis proves that the physical Li-ion battery becomes unstable when the estimated states of the observer enter instability. The trend filtering algorithm is able to detect such instability under large perturbations from the discharge current. Extensive simulation and experimental results demonstrate the effectiveness of the algorithms and its robustness under realistic perturbations.     

异步电机的非线性自适应反步控制器设计

针对描述异步电机的动态特性方程,在一些系统参数未知的情况下,应用分离子系统的方法和反向递推技术,设计了非线性自适应控制器.实现了电机对给定转速信号和磁通量信号的输出渐近跟踪控制,保证了整个系统的全局有界稳定性.仿真结果验证了该自适应控制策略的有效性.     

Discrete-time deadbeat model reference adaptive control of an adjustable-speed DC motor drive system

An imperfect model reference adaptive control for a DC motor drive system having bounded disturbances is proposed. The discrete-time model reference adaptive control algorithm proposed by Chiang and Chen (1987) with bounded disturbances is introduced to an Elettronica Veneta Mod. IBS-4/EV DC motor. This work shows that the adaptive controller can maintain good performance during startup, anticlockwise, or clockwise winding in the regulating reference signals.     

Wavelet energy based voice activity detection and adaptive thresholding for efficient speech coding

During the last five decades, extensive researches have been carried out in the field of speech compression, which has resulted in various techniques for speech coding. Researchers have been in full swing for more efficient speech coding and their effort is still continuing in different parts of the world. In this paper we are proposing an alternative method for better speech coding. In the proposed technique we use discrete wavelet transform to decompose the signal and wavelet energy is used to differentiate between active voice region and silence region in the speech signal. Depending upon the region’s status the system, different thresholding strategies have been chosen which leads to a better compression without any loss of speech intelligibility. The proposed method is evaluated in terms of qualitative and quantitative parameters. In this paper we also propose an alternative parameter for MOS values which is here after known as System Recognition Rate.     

基于嵌入式Linux的步进电机驱动程序设计

介绍了Linux驱动程序的实现机制,在分析步进电机和驱动程序接口的基础上,给出了一个在嵌入式Linux平台上编写步进电机驱动的实例.本平台基于Samsung公司的S3C2410X CPU,采用Linux2.4内核作为它的操作系统.介绍了如何通过对驱动程序的操作实现对步进电机的控制.在JXARM2410实验平台上的实验结果表明驱动运行正常.     

嵌入式Linux中NVRAM的实现方案及驱动设计

在CQ8401硬件平台和嵌入式Linux系统下,提出了NVRAM的实现方案,并设计实现了新的NVRAM的驱动.针对NVRAM的功能特性,利用嵌入式Linux平台,设计设备驱动程序与操作系统及外部设备的接口,实现了应用软件对硬件的正确的访问操作.对系统的性能进行了分析,并对结果进行了测试.该方法已成功运用于使用CQ8401开发板的网络路由器中,运行效果良好.