The Model Reference Adaptive Fuzzy Control for the Vehicle Semi-Active Suspension

The LQG control system is employed as vehicle suspension's optimal target system, which has an adaptive ability to the road conditions and vehicle speed in a limited bandwidth. In order to keep the optimal performances when the suspension parameters change, a model reference adaptive fuzzy control (MRAFC) strategy is presented. The LQG control system serves as the reference model in the MRAFC system. The simulation results indicate that the presented MRAFC system can adapt to the parameters variation of vehicle suspension and track the optimality of the LQG control system, the presented vehicle suspension MRAFC system has the ability to adapt to road conditions and suspension parameters change.

Automobile active suspension system with fuzzy control

A quarter-automobile active suspension model was proposed. High speed on/off solenoid valves were used as control valves and fuzzy control was chosen as control method . Based on force analyses of system parts, a mathematical model of the active suspension system was established and simplified by linearization method. Simulation study was conducted with Matlab and three scale coefficients of fuzzy controller (ke, kec, ku) were acquired. And an experimental device was designed and produced. The results indicate that the active suspension system can achieve better vibration isolation performance than passive suspension system, the displacement amplitude of automobile body can be reduced to 55%. Fuzzy control is an effective control method for active suspension system.

Linear Quadratic Integral Control for the Active Suspension of Vehicle

The quarter model of an active suspension is established in the form of controllable autoregressive moving average （CARMA） model. An accelerometer can be mounted on the wheel hub for measuring road disturbance; this signal is used to identify the CARMA model parameters by recursive forgetting factors least square method. The linear quadratic integral （LQI） control method for the active suspension is presented. The LQI control algorithm is fit for vehicle suspension control, for the control performance index can comprise multi controlled variables. The simulation results show that the vertical acceleration and suspension travel both are decreased with the LQI control in the low frequency band, and the suspension travel is increased with the LQI control in the middle or high frequency band. The suspension travel is very small in the middle or high frequency band, the suspension bottoming stop will not happen, so the vehicle ride quality can be improved apparently by the LQI control.

Fuzzy Control of Model Travel Tracking for Vehicle Semi-Active Suspension

The control strategy of the model travel tracking for the vehicle suspension sys tem is presented based on analyzing the responses of the vehicle suspension tra vel. A fuzzy control system of vehicle suspension is designed, in which the sus pension travel output of the adaptive LQG control system is taken as the tracking objective. The simulation results prove that the suspension travel and vertical acceleration can be tracked simultaneously with the simple fuzzy controller, and the tracking effect of fuzzy control is better than that of the PID controller.

HYBRID FUZZY CONTROL FOR ELECTRO-HYDRAULIC ACTIVE DAMPING SUSPENSION

A new control scheme, the hybrid fuzzy control method, for active dampingsuspension system is presented. The scheme is the result of effective combination of the statisticaloptimal control method based on the statistical property of suspension system, with the bang-bangcontrol method based on the real-time characteristics of suspension system. Computer simulations areperformed to compare the effectiveness of hybrid fuzzy control scheme with that of optimal dampingcontrol, bang-bang control, and passive suspension. It takes the effects of time-variant factorsinto full account. The superiority of the proposed hybrid fuzzy control scheme for active dampingsuspension to the passive suspension is verified in the experiment study.

Design and experiment of electro hydraulic active suspension for controlling the rolling motion of spray boom

Boom sprayer is one of the most commonly used plant protection machinery for spraying pesticide.Studies have shown that the efficiency of chemicals is highly correlated with the uniformity of spray distribution patterns.As the boom is a large and flexible structure,boom rolling leads to overlapping and leakage of the pesticides.In order to improve spray uniformity,the boom attitude should be kept parallel to the ground slope or to the crop canopy beneath the boom.Passive suspension can attenuate frequencies above its resonance frequency,but nothing can be done to align the boom to the sloping ground.Therefore,an active suspension system is designed,which includes DSP-based controller,a servo valve,a hydraulic cylinder,two ultrasonic sensors,one inertial attitude sensor,and the developed control procedures.In order to prevent the wrong response of the control system caused by the high frequency component due to uneven crop canopy or rough ground.A special signal processing algorithm was proposed,including the limiting filter,smoothing algorithm and data fusion algorithm based on optimal weight.The transient and steady-state performances of the boom control system using velocity feedforward PID algorithm were tested on a six DOF motion simulator.It can be seen that the low-frequency tracking performance of the boom was greatly improved after the electro-hydraulic active suspension was added.At the resonance frequency,the peak angle of active suspension and passive suspensions are 0.72°and 1.29°respectively,and the resonance peak is greatly reduced.The controller was implemented on a self-propelled boom sprayer and validated under field conditions,the standard deviation of the roll angle of the boom with active suspension is 0.40°,compared with 1.04°of the sprayer chassis.Experimental results show that the active suspension control system can effectively reduce the effect of ground excitation disturbance on the application process,and has good tracking performance for low frequency terrain change.

Active micro-vibration control based on improved variable step size LMS algorithm

The contradiction of variable step size least mean square(LMS)algorithm between fast convergence speed and small steady-state error has always existed.So,a new algorithm based on the combination of logarithmic and symbolic function and step size factor is proposed.It establishes a new updating method of step factor that is related to step factor and error signal.This work makes an analysis from 3 aspects:theoretical analysis,theoretical verification and specific experiments.The experimental results show that the proposed algorithm is superior to other variable step size algorithms in convergence speed and steady-state error.

Investigation of Semi-Active Hydro-Pneumatic Suspension for a Heavy Vehicle Based on Electro-Hydraulic Proportional Valve

Hydro-pneumatic suspension is widely used in heavy vehicles due to its nonlinear characteristics of stiffness and damping. However, the conventional passive hydro-pneumatic suspension can’t adjust parameters according to the complicated road environment of heavy vehicles to fulfill the requirements of the vehicle ride comfort. In this paper, a semi-active hydro-pneumatic suspension system based on the electro-hydraulic proportional valve control is proposed, and fuzzy control is used as the control strategy to adjust the?damping force of the semi-active hydro-pneumatic suspension. A 1/4?semi-active hydro-pneumatic suspension model is established, which is co-simulated with AMESim and MATLAB/Simulink. The co-simulation results show that the semi-active hydro-pneumatic suspension system can significantly reduce vibration of the vehicle body, and improve the suspension performance comparing with passive hydro-pneumatic suspension.

Research on adaptive anti-rollover control of kiloton bridge transporting and laying vehicles

The SPMT construction method is a new rapid construction technology of large urban overpass with unblocked traffic,and unstability of SPMT construction method equipment cannot be accurately described due to the concrete beam size,irregular shape and complex transport conditions,which is called kiloton bridge transporting and laying vehicle.The anti-rollover performance of SPMT suspension system is studied,and vehicle side slip angle and load transfer rate(LTR) are regarded as the evaluation indexes.An active suspension adaptive anti-rollover control model of SPMT,in which roll stability affected by the structural parameters and control parameters,is built based on fuzzy PID,and the effectiveness of the control method is verified through real vehicle test.

基于自适应LMS算法的跨声速风洞模型系统辨识

针对风洞试验模型系统辨识不准确的问题,利用自适应LMS(least mean square)滤波器模型对跨声速风洞模型进行系统辨识。由于实测信号中存在多模态耦合,为了提高系统辨识精准度,首先对输入输出信号作了FRF(frequency response analysis)分析得到试验模型俯仰方向前两阶模态,其次利用快速Fourier变换进行模态解耦,接着利用自适应LMS滤波器模型、传递函数模型、多项式模型对俯仰方向单模态进行系统辨识,最后得到了基于自适应LMS滤波器模型的俯仰方向一阶、二阶模态滤波器系数。通过对比不同数学模型的输出与输入之间的相关系数和均方误差及辨识结果,表明自适应LMS滤波器模型具有更高的系统辨识精准度和更简洁的数学模型结构。为后续风洞试验模型振动主动控制计算法的设计提供有力支撑。

基于滤波x-LMS算法的磁悬浮隔振器控制研究

针对自行研制的磁悬浮隔振器进行自适应前馈控制,设计了基于滤波x最小均方(Filtered x Least Mean Square——滤波x-LMS)算法的控制律。为了将滤波x-LMS算法应用于带有非线性特性的磁悬浮隔振系统,对滤波x-LMS算法进行了改进。在磁悬浮隔振系统上进行振动主动控制实验,实验结果表明,该控制算法取得了良好的减振效果。

基于LMS自适应滤波算法的电力变压器有源降噪系统

为了有效抑制电力变压器产生的高分贝低频噪声,针对变压器有源降噪系统开展了相关研究。结合实验条件,在分析变压器噪声时域及频域特点的基础上,合理选择了有源降噪系统类型。通过仿真和理论分析了收敛系数、滤波阶数以及系统采样频率对有源降噪系统采用的LMS自适应滤波算法收敛性、稳定性以及降噪效果的影响。搭建了变压器噪声在线监测及有源降噪软件控制平台,并针对变压器噪声特点合理选择了硬件系统设备。结果表明,在变压器噪声有源降噪实验中,噪声低频区域降噪效果显著,在误差传声器处取得了5-10 d B的降噪效果,平均声能量密度下降了68.38%-90%,验证了LMS算法的有效降噪性,以及所构建的有源降噪系统对变压器噪声在线监测与抑制的可靠性。

基于LMS算法的磁悬浮轴承系统振动补偿

主动磁悬浮轴承转子高速旋转时会对系统产生周期性不平衡激振力响应,此响应会降低系统的控制精度、稳定性以及限制转子速度的提高等。针对此响应对系统的影响,首先,从轴承转子机械特性及系统控制过程分析系统周期性力产生的原因;其次,以振动在系统控制过程中体现的正弦形式信号为处理对象,采用最小均方差(LMS)算法与数字PID联合控制的方法实现滤波补偿;然后,通过分析定步长LMS算法与PID参数及被处理信号的频率的相互影响,提出了一种依据转子位移信号频率变化而实时变频切换补偿的控制策略;最后通过实验台实验验证了方法的有效性,为轴承转速的进一步提高奠定基础。

一种应用Fx LMS算法的双层隔振试验装置

振动主动控制中次级通道的存在会对控制效果造成影响,为了减小影响,采用Fx LMS(Filter-x Least Mean Square)自适应滤波算法,通过调整步长更新滤波器参数进行自适应控制。平台使用Compact-RIO控制器并采用Lab VIEW对其进行编程,通过设置参数对不同系统进行主动控制。控制分为三部分:参数设置、次级通道辨识、误差信号的控制。在自适应算法的理论和仿真分析基础上,进一步在c RIO实时控制平台上进行实验研究,对双层隔振平台采用自适应算法实现主动控制,取得理想的控制效果。

磁悬浮隔振器分块归一化LMS算法控制研究

针对自行研制的磁悬浮隔振器,设计了基于分块归一化LMS(Block Normalized Least Mean Square)算法的控制律。该算法不需要对次级通道进行建模,且结构简单,易于实现。把该算法应用于带有非线性特性的磁悬浮隔振实验平台,并对其进行振动主动控制实验。实验结果表明:该控制算法收敛速度较快,取得了良好的隔振效果。

归一化LMS算法在主动隔振中的仿真研究

针对自适应LMS(Least Mean Square)算法稳定性受自适应常数影响的情况,把归一化LMS算法引入到主动隔振控制中,并以一基于磁致伸缩作动器的双层隔振平台为研究对象,利用Matlab进行仿真,结果表明采用NLMS(Normalized Least Mean Square)算法可使系统的稳定性得到显著提高。

误差通道建模误差对多误差LMS算法性能的影响

本文证明了，在多通道自适应宽带有源噪声控制中，由于误差通道建模误差的存在，多误差LMS算法是条件收敛的，并推导了保证算法收敛的条件，还证明了，算法收敛后，得到自适应滤波器权值一般只是理论上最优值的有偏估计，计算机仿真结果验证了所得结论．

LMS自适应主动控制汽车悬架系统试验研究

以汽车操纵稳定性及行驶平顺性为控制目标,确定汽车系统的簧上质量加速度、车轮动载荷、悬架动挠度为具体评价参数。选择LMS自适应滤波算法,通过调整自适应滤波器的权系数使二次性能指标最小,根据单个样本方差的负梯度来调节权系数,得到控制输出。针对简化的汽车模型,在路面信号作为激励源的仿真研究过程中,算法对悬架系统的振动控制收到了较好的效果。在两自由度的悬架系统试验台架上进行了试验研究,结果进一步证明该算法的有效性,表明LMS自适应控制策略在主动悬架系统中的应用切实可行。

基于LMS自适应滤波的模糊控制主动悬架研究

以车辆操纵稳定性及行驶平顺性为控制目标 ,根据路面 -车辆系统的特点 ,提出一种在线可调整的模糊控制算法 ,利用LMS自适应模块调整模糊控制器的自调整因子 ,改善单一模糊控制算法对专家先期经验的依赖。针对简化的车辆模型 ,以路面信号作为激励源 ,进行悬架系统的振动控制研究 。

基于FX-LMS算法的微振动主动隔振控制系统开发

控制系统是基于压电智能结构的各类微振动主动隔振系统的核心部分,而控制性能好、运算快速、实现方便的控制算法则是控制系统开发的关键。基于FIR数字滤波器,并应用FX-LMS自适应算法,对基于压电智能结构的各类微振动主动隔振系统的控制算法进行推导,并对其实现过程进行分析,以便于控制系统开发。在此基础上,利用该FX-LMS算法开发了某一维微振动主动隔振平台的自动控制系统,用于对该算法的控制效果进行实验测试和验证。实验结果表明,所推导的FX-LMS算法具有良好的控制效果,应用领域广阔。