磁悬浮自适应控制

以自适应PID结构针对磁悬浮系统设计非线性控制器，并在磁悬浮球装置上进行了试验，结果证实这种控制器具有完全的鲁棒性、良好的参数适应性，设计方法也有广泛的适用性。     

永磁悬浮带式输送机悬浮支撑系统稳定性研究

建立了永磁悬浮带式输送机悬浮支撑系统三维模型,对不同磁性输送带形状、永磁体布置形式、永磁体形状、偏载条件下永磁悬浮支撑系统稳定性进行了仿真。结果表明:槽型磁性输送带稳定性优于平型、V型磁性输送带,且承载能力表现最稳定;永磁体采用槽型结构时磁性输送带稳定性和承载能力较好;偏载会加剧磁性输送带的跑偏。为有效解决磁性输送带跑偏问题,设计了一种槽型磁性输送带防跑偏装置,通过在槽型磁性输送带两侧安装辅助辊轮,能进一步提高永磁悬浮带式输送机悬浮支撑系统的稳定性。     

Modelling and simulation of locomotive driver's seat vertical suspension vibration isolation system

The paper describes the simulation of a vertical seat suspension system with a variable damper. The model presented describes a real damper with bushings and is an extension of the classical linear SDOF oscillatory system. Transfer functions were identified from laboratory measurements and the mechano-mathematical model produced was validated by field measurements. The seat cushion parameters were identified from laboratory measurements and combined with standardized vertical (z-axis) seated human body models (ISO 5982 and DIN 45676). These models, together with an inert mass human body model, were used to predict the vibration mitigation performance of the seat–occupant system. The results were compared to data obtained from field measurements under real operating conditions. It was found that the use of the inert mass human body model resulted in the smallest differences between predicted and measured system vibration isolation performance for the field excitation in the frequency band up to 4.5 Hz, where most of the vibratory energy was present in the field. Hence this simplified model is suggested for prediction of vibration influence on locomotive driver under field conditions.

Relevance to the industry

The developed model using various seated human body models in the vertical direction revealed that an inert mass instead of the human body model may be sufficient for reliable prediction of seat vibration mitigation properties in rail vehicles. The developed model and findings reported here assisted in development of an improved locomotive driver's seat.     

基于磁流变阻尼器的汽车半主动悬架的振动控制

在对磁流变阻尼器的输出特性进行实验测试和理论分析的基础上,建立了以磁流变阻尼器作为执行器件的1/4车半主动悬架模型,设计了一种双输入单输出的模糊逻辑控制器,并进行了仿真研究,在时间和频率域中对磁流变阻尼器振动响应进行评价,结果表明:与被动悬架相比,该系统有效地抑制了车身在人体敏感频率段的振动,提高了乘坐舒适性.     

Vibration control of a nonlinear quarter-car active suspension system by reinforcement learning

This article presents the investigation of performance of a nonlinear quarter-car active suspension system with a stochastic real-valued reinforcement learning control strategy. As an example, a model of a quarter car with a nonlinear suspension spring subjected to excitation from a road profile is considered. The excitation is realised by the roughness of the road. The quarter-car model to be considered here can be approximately described as a nonlinear two degrees of freedom system. The experimental results indicate that the proposed active suspension system suppresses the vibrations greatly. A simulation of a nonlinear quarter-car active suspension system is presented to demonstrate the effectiveness and examine the performance of the learning control algorithm.     

Vibration control of vehicle active suspension system using a new robust neural network control system

The main problem of vehicle vibration comes from road roughness. For that reason, it is necessary to control vibration of vehicle’s suspension by using a robust artificial neural network control system scheme. Neural network based robust control system is designed to control vibration of vehicle’s suspensions for full suspension system. Moreover, the full vehicle system has seven degrees of freedom on the vertical direction of vehicle’s chassis, on the angular variation around X-axis and on the angular variation around Y-axis. The proposed control system is consisted of a robust controller, a neural controller, a model neural network of vehicle’s suspension system. On the other hand, standard PID controller is also used to control whole vehicle’s suspension system for comparison.Consequently, random road roughnesses are used as disturbance of control system. The simulation results are indicated that the proposed control system has superior performance at adapting random road disturbance for vehicle’s suspension.     

含间隙弹簧振动系统的非线性模态特性

针对含间隙的两自由度弹簧-质量分段振动系统的非线性模态开展了研究.首先,解析确定了分段保守自治系统发生同相和反相模态运动的初始位移,并采用加权平均方法确定了分段振动系统的模态频率,及其在位形空间模态曲线.然后,采用数值方法求解了系统的非线性模态曲线和模态频率,与本文获得的解析模态频率比较,说明本文的结果较等效模态频率有更好的精度.研究结果表明:在一定的参数条件下,系统的非线性模态个数会高于系统的自由度数目,系统可能发生内共振,而产生多余模态.多余模态运动是两振子同向振动中含有异向振动,说明多余模态是在同相模态运动和反相模态运动之间转换的模态.     

基于等效模态阻尼的复合隔振系统振动计算方法

基于线性黏弹性假设,将应变能阻尼理论推广到复合隔振系统的等效模态阻尼计算中,运用Python和Abaqus编制相应的计算程序,该程序可考虑材料阻尼的频变特性。以多种材料组成的船舶双层复合隔振系统为算例,计算其等效模态阻尼和隔振器等效阻尼系数。分别采用直接积分法和模态叠加法计算系统振动响应,对比设备、筏架、船底壳的振动加速度响应,验证基于等效模态阻尼的模态叠加法的准确性。结果表明,该方法可以准确计算复杂组合模型的模态阻尼,算例的振动响应计算结果一致性较好,用模态叠加法可以大幅提高复合隔振系统稳态振动响应的计算效率。     

Predictive functional control based on fuzzy model: magnetic suspension system case study

Fuzzy model based predictive functional controller (FPFC) is applied to the magnetic suspension system—a pilot plant for magnetic bearing. High quality control requirements are short settle time with a-periodical step response and zero steady-state error. Open loop unstable process was stabilised with linear lead compensator. The FPFC was used as a cascade controller. Due to some model uncertainties, the Takagi–Sugeno fuzzy model of stabilised system was obtained using fuzzy identification. Comparing to PID, it improved quality and robustness performance. With its computational efficiency, it proved to be ideal solution for high sampling frequency systems.     

结合自编码器和卷积神经网络的推荐系统

传统推荐系统以评分作为推荐依据,没有分析与利用用户的评论内容,导致推荐系统存在推荐准确性低和数据稀疏性的问题.针对这种情况,结合降噪自编码器和卷积神经网络提出一种推荐系统.通过卷积神经网络学习评论内容在方面级的情感和观点,基于降噪自编码器对方面级的观点集合进行归纳和分组,以三阶张量分解技术为基础,推断出用户对项目的综合...     

Vibration attenuation performance of suspension seats for off-road forestry vehicles

Four different types of vertical suspension seats were evaluated in the laboratory and in the field in order to measure their adaptability for attenuating whole-body vibration in log skidders used in the forest industry. Laboratory testing first consisted of determining the static and dynamic characteristics of the seats such as the static stiffness of the cushions and suspension systems and the hysteresis parameters and damping properties of the cushions. The vibration attenuation characteristics of the seats were then measured using a laboratory test rig simulating a driver work station. The influence of amplitude of excitation and the variations in seat height on the vibration attenuation performance of the suspension seats was evaluated for sinusoidal excitations in the frequency range of 0.2–8.0 Hz. The seats were then field tested during normal skidding operations to determine their vertical transmissibility characteristics and to compare the vibration exposure that results from operating a skidder while being equipped with a suspended seat, as opposed to having an unsuspended one. There was generally good agreement between the transmissibility characteristics measured in the laboratory and in the field. The results of vibration transmissibility and exposure are helpful in identifying one of the suspension seats as being the most appropriate for attenuating vertical whole-body vibration on skidders, while conforming at the same time to the basic dimensional characteristics and stability required for safe operation of such vehicles.     

A compact electromagnetic micro-actuator using the meander springs partially exposed to magnetic field

We present the design, fabrication, and testing of a compact electromagnetic micro-actuator using meander springs that are partially exposed to the magnetic field. The previous electromagnetic micro-actuators using cantilever springs require large electromagnetic force for large displacement actuation and therefore require high-current input and a large magnet. The previous electromagnetic actuators using low-stiffness meander springs are limited in large displacement actuation because actuation forces cancelled each other due to changes in the current path under the magnetic field. In this paper, we compare two prototypes: a conventional prototype F with the meander springs exposed fully to the magnetic field and the present prototype P with the meander springs partially exposed to the magnetic field. In the experimental study, the amplitude of prototype P is measured as 30.49 ± 0.36 µm at the 40 mA square input current, while the amplitude of prototype F is measured as 26.02 ± 0.65 µm. The amplitude of prototype P is 17.2 % larger than that of prototype F, verifying the effect of partial exposure of the meander springs to the magnetic field. Therefore, we experimentally demonstrate the large-displacement actuation performance of the present actuator using the partial exposure of the meander springs to the magnetic field.     

Masterminding change by combining secure system design with security risk assessment

International Journal on Software Tools for Technology Transfer - This track introduction presents the results of the Workshop on Security practices for Internet of Things, SPIoT held at ETAPS in...     

集中荷载作用下悬索的主共振分析

针对集中荷载作用下两端固定悬索在集中荷载点外激励作用下悬索系统发生的强迫振动,研究了激励频率接近悬索主共振频率时,系统产生的主共振.采用多尺度法,得到了各阶振型的主共振分叉图和主共振分叉点的解析解.通过实例计算,得到了悬索的各阶振型的线性频率与集中荷载以及集中荷载的位置关系,还得到了各阶振型的主共振分叉图和各阶振型的主共振点相平面图.     

半主动悬挂系统模糊控制系统设计研究

阐述了我国高速列车横向悬挂采用半主动悬挂控制横向振动问题的必要性.介绍了高速列车横向半主动悬挂控制所采用的模糊控制方法,并进行了模糊控制系统的设计.     

基于双旋翼和磁悬浮的远程实验室的建设

远程实验室系统,是基于飞速发展的Internet网络,利用计算机自动控制技术等组成的网上远程高级控制系统。远程实验室系统在高级专业培训中具有广阔的应用前景和发展空间。本文采用B／S模式的远程监控方案,将双旋翼和磁悬浮这两种多输入多输出的实验设备作为被控对象,进行仿真研究。论文介绍了基于Web的远程监控系统的实现,并完成客户端程序的设计,给出了双旋翼和磁悬浮的监控界面以及响应曲线。     

Multivariable frequency domain controller for magnetic suspension and balance systems

The magnetic suspension and balance system for an airplane model in a large wind tunnel is considered. In this system, superconducting coils generate magnetic forces and torques on the magnetized soft iron core of the airplane model. The control system is a position servo where the airplane model, with six degrees of freedom, follows the reference static or dynamic input commands. The controller design, based on the characteristic loci method, minimizes the effects of aerodynamic and inertial cross-couplings, and provides the specified dynamic response.     

基于IFIX和施耐德PLC的燃煤锅炉控制系统

为了提高工业燃煤锅炉控制的自动化水平和安全生产,运用先进的自动化技术、计算机技术和网络通讯技术对工业锅炉进行监控和管理具有重要意义。本文采用QUANTUMPLC,IFIX4．0组态软件和工业以太网通讯技术相结合,研发了工业燃煤锅炉控制系统,利用Concept2．6编程软件设计锅炉控制的梯形图,实现了水位三冲量、燃烧过程和蒸汽压力自动控制等功能。工业以太网通讯连接实时性能较好,数据传输率很高。采用IFIX4．0组态软件编写的监控程序具有功能完善、操作简便、可视性好、人机对话功能强等优点。     

Dynamic project performance estimation by combining static estimation models with system dynamics

Changes in user requirements or project personnel occur frequently during project execution particularly in long-term and large-size projects. We need a tool which can estimate the effects of changing conditions to effectively manage the project.This paper proposes a simulation method for dynamic project performance in terms of effort, schedule, and defect density changes in a dynamic project environment by combining COCOMO II with system dynamics. We apply expert judgment technique to overcome the lack of empirical data on the effects of dynamic project environment. We develop a simulation tool (available on the authors’ website) which has model adjustment parameters to reflect experts’ estimation on project characteristics. The simulation experiment on a military application development project demonstrates that the developed model can show the behavioral characteristics of a project suffering unanticipated and uncontrolled requirements creep. This helps project managers understand interactions between project factors and proactively evaluate and control the effects of dynamic project environment.     

Robust vision-based localization by combining an image-retrieval system with Monte Carlo localization

In this paper, we present a vision-based approach to mobile robot localization that integrates an image-retrieval system with Monte Carlo localization. The image-retrieval process is based on features that are invariant with respect to image translations and limited scale. Since it furthermore uses local features, the system is robust against distortion and occlusions, which is especially important in populated environments. To integrate this approach with the sample-based Monte Carlo localization technique, we extract for each image in the database a set of possible viewpoints using a two-dimensional map of the environment. Our technique has been implemented and tested extensively. We present practical experiments illustrating that our approach is able to globally localize a mobile robot, to reliably keep track of the robot's position, and to recover from localization failures. We furthermore present experiments designed to analyze the reliability and robustness of our approach with respect to larger errors in the odometry.