Computer simulation of active suspension based on the full-vehicle model

The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model.But it is not enough to use this kind of model for practical applications.In this paper,based on considering the influence of factors such as,seat and passengers a MDOF(multi-degree-of-freedom)model describing the vehicle motion is set up.The MODF model,which is 8DOF of four independent suspensions and four wheel tracks,is more applicable by comparison of its analysis result with some conventional vehicle models.Therefore,it is more suitable to use the 8DOF full-car model than a conventional 4DOF half-car model in the active control design for car vibration.Based on the derived 8DOF odel,a controller is designed by using LQ(linear quadratic)control theory,and the appropriate control scheme is selected by testing various performance indexes.Computer simulation 8is carried out for a passenger car running on a road with step disturbance and random road disturbance expressed by Power Spectral Density(PSD).Vibrations corresponding to ride comfort are derived under the foregoing road disturbances.The response results for uncontrolled and controlled system are compared.The response of vehicle vibration is greatly suppressed and quickly damped.which testifies the effect of the active suspenson.The results achieved for various controllers are compared to invesigate the influence of different control schemes on the control effect.     

Active disturbance rejection control for hydraulic width control system for rough mill

The highly nonlinear behavior of the system limits the performance of classical linear proportional and integral (PI) controllers used for hot rolling. An active disturbance rejection controller is proposed in this paper to deal with the nonlinear problem of hydraulic servo system in order to preserve fast response and small overshoot of control system. The active disturbance rejection (ADR) controller is composed of nonlinear tracking differentiator (TD),extended state observer (ESO) and nonlinear feedback (NF) law. An example of the hydraulic edger system case study is investigated to show the effectiveness and robustness of the proposed nonlinear controller,especially,in the circumstance of foreign disturbance and working condition variation,compared with classic PI controller.     

Mass spectrometry-based protein-protein interaction techniques and their applications in studies of DNA damage repair

Proteins are major functional units that are tightly connected to form complex and dynamic networks.These networks enable cells and organisms to operate properly and respond efficiently to environmental cues.Over the past decades,many biochemical methods have been developed to search for protein-binding partners in order to understand how protein networks are constructed and connected.At the same time,rapid development in proteomics and mass spectrometry(MS)techniques makes it possible to identify interacting proteins and build comprehensive protein-protein interaction networks.The resulting interactomes and networks have proven informative in the investigation of biological functions,such as in the field of DNA damage repair.In recent years,a number of proteins involved in DNA damage response and DNA repair pathways have been uncovered with MS-based protein-protein interaction studies.As the technologies for enriching associated proteins and MS become more sophisticated,the studies of protein-protein interactions are entering a new era.In this review,we summarize the strategies and recent developments for exploring protein-protein interaction.In addition,we discuss the application of these tools in the investigation of protein-protein interaction networks involved in DNA damage response and DNA repair.     

Nonlinear stochastic optimal bounded control of hysteretic systems with actuator saturation

A modified nonlinear stochastic optimal bounded control strategy for random excited hysteretic systems with actuator saturation is proposed. First, a controlled hysteretic system is converted into an equivalent nonlinear nonhysteretic stochastic system. Then, the partially averaged Itoe stochastic differential equation and dynamical programming equation are established, respectively, by using the stochastic averaging method for quasi non-integrable Hamiltonian systems and stochastic dynamical programming principle, from which the optimal control law consisting of optimal unbounded control and bang-bang control is derived. Finally, the response of optimally controlled system is predicted by solving the Fokker-Planck-Kolmogorov （FPK） equation associated with the fully averaged Itoe equation. Numerical results show that the proposed control strategy has high control effectiveness and efficiency.     

Nonlinear decoupling controller design based on least squares support vector regression

INTRODUCTION Most practical systems are multivariate nonlin- ear systems. In general, the MIMO (multiple inputs and multiple outputs) systems are coupled. This cou- pling affects the effectiveness of a specific loop con- troller on the corresponding output, and in some case, may become serious and cause many difficulties to the control system design. How to decouple the mul- tivariate systems and design practical controllers is one of the major issues in nonlinear control area. In recen…     

Response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control

We studied the response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control using the stochastic averaging method. First, the time-delayed feedback bang-bang control force is expressed approximately in terms of the system state variables without time delay. Then the averaged It6 stochastic differential equations for the system are derived using the stochastic averaging method. Finally, the response of the system is obtained by solving the Fokker-Plank-Kolmogorov （FPK） equation associated with the averaged lt6 equations. A Duffing oscillator with time-delayed feedback bang-bang control under combined harmonic and white noise excitations is taken as an example to illus- trate the proposed method. The analytical results are confirmed by digital simulation. We found that the time delay in feedback bang-bang control will deteriorate the control effectiveness and cause bifurcation of stochastic jump of Duffing oscillator.     

J-integral resistance curve testing and evaluation

In this paper a critical review is presented ofthe history and current state of the art of J-integral resistance curve testing and experimental evaluation methods in conjunction with a discussion of the development of the plane strain fracture toughness test standard ASTM E 1820 developed by American Society for Testing and Materials （ASTM）. Early research efforts on this topic are reviewed first, These include the J-integral concept, experimental estimates of the J-integral for stationary cracks, load line displacement （LLD） and crack mouth opening displacement （CMOD） based ηfactor equations, different formulations of J-integral incremental equations for growing cracks, crack growth corrected .JR curve determination, and experimental test methods. Recent developments in J-R curve testing and evaluation are then described, with emphasis on accurate J-integral incremental equations, a normalization method, a modified basic method, a CMOD direct method with use of incremental equations, relationships of plastic geometry factors, constraint-dependent J-R curve testing and correction approaches. An overview of the present fracture toughness test standard ASTM E1820-08a is then presented. The review shows that after more than 40 years of investigation and development, the J-integral resistance curve test methods in ASTM E1820 have become simpler, more cost-effective and more accurate.     

基于超磁致伸缩材料的非圆曲面形活塞销孔加工新型机构

To bear more loads for heavy truck pistons, the shape of heavy truck piston pinhole is often designed as noncylinder form. Current methods cannot meet the needs for precision machining on non-cylinder piston pinhole （NCPPH）. A novel mechanism based on giant magnetostrictive materials （GMM） is presented. New models are established for the servo mechanism, GMM, and magnetizing force of the control solenoid to characterize the relationship between the control current of the solenoid and the displacement of the giant magnetostrictive actuator （GMA）. Experiments show that the novel mechanism can meet the needs to perform fine machining on NCPPH effectively.     

Investigations on control algorithm of steady-state cornering and control strategy for dynamical correction in a steer-by-wire system

To improve the handling performance of a steer-by-wire （SBW） vehicle, a series of control logics are proposed. Firstly, an algorithm for enhancing the maneuvering in steady-state cornering is presented. On this basis, two categories of control strategies are used to dynamically correct and compensate the transient state steering responses and vehicle behaviors. Simulator tests including subjective evaluations and virtual field tests are both conducted to make comprehensive investigations on the series of control logics. The subjective evaluations demonstrate that the SBW vehicle with a specifically selected value of steering sensitivity tends to be more desirable for driving than a conventional one in which a fixed steering ratio exists. The virtual field tests indicate that the control strategies for dynamical correction and compensation could effectively improve the handling per- formances of an SBW vehicle by reducing the work load of drivers, enhancingthe track-holding performance, and improving steering response properties.     

用于电力系统故障电流限制器的快速合闸开关研究

This paper presents a new type of fault current limiter(FCL) based on fast-closing switch,which is composed of a capacitor bank and a reactor in series.The main control component is a fast-closing switch connected in parallel with the capactitors,which is drien by the electromagnetic repulsion force.It can response the order within 1 ms.When fault occurs,the switch closes and the capacitors are bypassed.and the fault current is limited by the reactor,Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast-closing switch,it is feasible to develop the FCL with low cost and high reliability.     

基于形状记忆合金的多层钢框架被动控制研究

通过形状记忆合金（SMA）材料的超弹性性能试验确定了SMA材料的各项力学性能参数,根据结构的振动控制理论,针对框架结构剪切型变形的特点,建立了SMA拉索对结构进行被动控制的运动方程。然后针对不同的控制方案,应用ANSYS有限元程序,仿真分析了多层钢结构模型在地震激励下的高度非线性动力时程响应,研究了SMA被动拉索的控制效果。     

轮式微型机器人运动机理与步态规划

在一种新型形状记忆合金驱动器的基础上,研制了一种微型蠕动机器人,该机器人采用轮式移动机构.对形状记忆合金驱动器、轮式移动机构的结构和运动机理以及机器人的步距扩大原理进行了讨论.并在此基础上,对机器人的直线运动步态和转弯步态进行了规划,使机器人在偏心轮自锁机构和换向机构作用下,不但可以前后运动,还具有主动转弯能力,在一定程度上克服了传统的形状记忆合金机器人移动速度慢、只能被动转弯的缺点.最后对形状记忆合金驱动器所需加热电流及该机器人的运动性能进行了试验分析.     

反推自适应控制与滑模控制在交流伺服电机中的应用比较

针对AC伺服电机系统,在转矩及转动惯量变化情况下,对比反推自适应控制和滑膜控制两种方法在系统参数变化和阻力扰动的鲁棒性。仿真情况包括理想模型、摩擦力扰动、执行器饱和等。仿真结果表明反推自适应控制对系统变化具有很强鲁棒性,但是更容易受到执行器饱和影响;滑模控制方法更容易实现,但是在摩擦扰动存在情况下,振动式冲击难以消除。     

Proportional-integral-derivative control of nonlinear half-car electro-hydraulic suspension systems

This paper presents the development of a proportional-integral-derivative (PID)-based control method for application to active vehicle suspension systems (AVSS). This method uses an inner PID hydraulic actuator force control loop, in combination with an outer PID suspension travel control loop, to control a nonlinear half-car AVSS. Robustness to model uncertainty in the form of variation in suspension damping is tested, comparing performance of the AVSS with a passive vehicle suspension system (PVSS), with similar model parameters. Spectral analysis of suspension system model output data, obtained by performing a road input disturbance frequency sweep, provides frequency response plots for both nonlinear vehicle suspension systems and time domain vehicle responses to a sinusoidal road input disturbance on a smooth road. The results show the greater robustness of the AVSS over the PVSS to parametric uncertainty in the frequency and time domains.     

具有凸多面体不确定参数Delta算子时滞系统的可靠保性能控制

研究Delta算子描述的线性不确定时滞系统的可靠保性能控制问题。考虑系统含有具有凸多面体不确定性参数和连续模型执行器故障,根据Lyapunov稳定性理论,给出对于所有允许的不确定性和执行器故障．均使闭环系统渐近稳定且给定性能指标具有一定上界的状态反馈控制器的存在条件,由此提出相应控制器的设计方法。通过数值算例验证了设计方法的可行性。     

Nonlinear Analysis of Shape Memory Alloy Component in Rotor System

The active control of rotor vibration was studied while shape memory alloy (SMA) spring component was chosen as bearing of rotor system. The vibration of rotor system was controlled by the phase transformation of SMA with electric heating method. The SMA spring component has nonlinear coupling problem of thermal stress and thermal elasticity, because thermal constants α,β and elasticity constants γ, G vary with temperature when temperature changes sharply. Because δ,ε were both small parameters, their square items could be ignored and approximate results were obtained by perturbation. The characters of α,β, γ, G changing with temperature were analyzed. Results show that the character of thermal diffusivity ot changes with temperature, which cannot influence U,Ψ,So the nonlinearity of ot can be ignored; the character of,β changes with temperature,which cannot influence U, but influences Ψ at high temperature; the character of γ, G change with temperature, which cannot influence Ψ, but influences U with U^(01) ε. The more γ ,G, the more their influence on U;the nonlinearity of βT/pcvεkk influences U and Ψ, which must be calculated.     

An approach to the capsule endoscopic robot with active drive motion

Commercialized capsule-type endoscopes move passively by peristaltic waves (and gravity), which makes it difficult for doctors to diagnose the areas of interest more thoroughly and actively. To resolve this problem of passivity, it is necessary to find a special locomotion principle, which fits the gastrointestinal (GI) tract. In this paper, a legged locomotive mechanism with shape memory alloy (SMA) actuation based on the peristaltic principle is proposed, and then the structure of the locomotion mechanism is introduced. Based on the preliminary results, the design, modeling, and fabrication of an SMA microactuation concept for application in an endoscopic capsule are given, as well as the SMA spring and legged component design, which is the core section of the system design. We used the pseudo-rigid-body model (PRBM) to analyze nonlinear and large deflections of the SMA legged component. Thus, a prototype endoscope with an SMA spring and six legged components was designed and fabricated. It is 15 mm in diameter and 33 mm in total length, with a hollow space to house other parts needed for endoscopy such as a camera, a radio frequency (RF) module, and sensors. During testing, the locomotive mechanism was effective in a plastic tube environment.     

一类多目标分档寻优控制

模糊控制被誉为21世纪的核心技术，其原理与手段不同于常规控制，笔者提出在模糊控制过程中实行“暂态粗调控制”及“稳态细调控制”的思想，使控制器具有较快的响应时间和较高的稳态精度，具有重要的理论意义和工程实用价值．