STATISTIC LINEARIZATION CONTROL FOR HYDRAULIC ACTIVE DAMPING SUSPENSION

A statistic linearization analysis method of bad nolinear hydraulic active damping suspension is provided.Also the optimum control strategy of semi active suspension and graded control strategy based on it are puted forward.Experimental researches are carried out on a 2 DOF(degree of freedom) hydraulic active damping suspension test system.The results showed that an excellent control effectiveness could be obtained by using statistic linearization optimum control which unfortunely requests continuously regulationg the damp in an accurate way and costs much in engeering application.On the contrary,the results also showed that graded control is more practicable which has a control effectiveness close to the optimum control and costs less.

Robust force tracking control via backstepping sliding mode control and virtual damping control for hydraulic quadruped robots

In order to improve the force tracking performance of hydraulic quadruped robots in uncertain and unstructured environments,an impedance-based adaptive reference trajectory generation scheme is used.Secondly,in order to improve the robustness to environmental changes and reduce the contact force errors caused by trajectory tracking errors,the backstepping sliding mode controller is combined with the adaptive reference trajectory generator.Finally,a virtual damping control based on velocity and pressure feedback is proposed to solve the problem of contact force disappearance and stall caused by sudden environmental change.The simulation results show that the proposed scheme has higher contact force tracking accuracy when the environment is unchanged;the contact force error can always be guaranteed within an acceptable range when the environment is reasonably changed;when the environment suddenly changes,the drive unit can move slowly until the robot re-contacts the environment.

Force Control Compensation Method with Variable Load Stiffness and Damping of the Hydraulic Drive Unit Force Control System

Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit（HDU）, and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this paper has positive compensation effects on the load characteristics variation, i.e., this method decreases the effects of the load characteristics variation on the force control performance and enhances the force control system robustness with the constant PID parameters, thereby, the online PID parameters tuning control method which is complex needs not be adopted. All the above research provides theoretical and experimental foundation for the force control method of the quadruped robot joints with high robustness.

Study on Outboard Inductive Damping Valve in Hydro-pneumatic Suspension

A new outboard inductive damping valve without any electronic control system is developed. Its working principle,structure and external characteristic are studied. Its mathematical model is presented and its damping characteristic is investigated on the basis of fluid continuity equation,differential equations of motion and Bernoulli equation. The influence of the valve parameters on the damping characteristic is studied numerically. The effects of outboard inductive damping valve and common damping valve on ride and tire load are compared also. The external characteristic of the valve is verified in bench test. The results show that the valve’s mathematical model is quite accurate and the developed valve can be adjust in two stages,which can also meet the requirements of the dynamic characteristic of the vehicle suspension system.

Fuzzy Hybrid Control of Vibration Attitude of Full Car via Magneto-rheological Suspensions

A magneto-rheological（MR） semi-active suspension system with the controllable damping forces has received more attention in reducing the vibration of a vehicle. However, many control strategies only discussed one or two vibration states of the vehicle based on a quarter-car model or a half vehicle model via MR suspensions. They cannot provide a satisfying whole-vehicle performance on a road test. Hence, a full car vibration model via an MR suspension system is proposed. To reduce the heave, pitch and roll motion of the vehicle body and the vertical vibration of four wheels, a fuzzy hybrid controller for vibration attitude of full car via MR suspensions is proposed. First, a skyhook-fuzzy control scheme is designed to reduce the heave, roll and pitch motion of the vehicle body. Second, a revised ground hook control strategy is adopted to decrease the vertical vibration of the wheels. Finally, a hybrid control scheme based on a fuzzy reasoning method is proposed to tune the hybrid damping parameter, which is suitable for coordination the attitude of the vehicle body and the wheels. A test and control system for the vibration attitude of full car is set up. It is implemented on a car equipped with four MR suspensions. The results on random highway and rough road indicate that the fuzzy hybrid controller can decrease the vibration accelerations of the vehicle body and the wheels to 65%-80% and 80%-90%, respectively. It reduces the automotive vibrations of heave, roll and pitch more effectively than a passive suspension and an MR suspension with a traditional hybrid control scheme so that it achieves better ride comfort and road holding concurrently. This paper proposes a new fuzzy hybrid control（FHC） method for reducing vibration attitude of full car via MR suspensions and develops a road test to evaluate the FHC.

SEMI-ACTIVE CONTROL OF VEHICLE SUSPENSION WITH MAGNETO-RHEOLOGICAL DAMPERS:PART Ⅰ——CONTROLLER SYNTHESIS AND EVALUATION

A modified skyhook-based semi-active controller is proposed for implementing an asymmetric control suspension design with symmetric magneto-rheological （MR） dampers. The controller is formulated in current form, which is modulated by integrating a continuous modulation and an asymmetric damping force generation algorithms, so as to effectively minimize switching and hysteretic effects from the MR-damper. The proposed controller is implemented with a quarter-vehicle MR-suspension model, and its relative response characteristics are thus evaluated in terms of defined performance measures under varying amplitude harmonic, rounded pulse and random excitations. The sensitivity of the semi-active suspension performance to variations in controller parameters is thoroughly evaluated. The results illustrate that the proposed skyhook-based asymmetric semi-active MR-suspension controller has superior robustness on the system parameter variations, and can achieve desirable multi-objective suspension performance.

SEMI-ACTIVE CONTROL OF VEHICLE SUSPENSION WITH MAGNETO-RHEOLOGICAL DAMPERS PARTⅡ——EVALUATION OF SUSPENSION PERFORMANCE

The design and analysis of an intelligent vehicle suspension with MR dampers should address hybrid semi-active control goals, such as rejection of current-switching discontinuity and MR-damper hysteresis, asymmetric damping from the symmetric MR-damper design, robustness on the vehicle operation parameter uncertainties and consideration of essential multiple suspension goals. Following the proposed skyhook-based asymmetric semi-active controller （Part I ） for achieving the above goals, herein, a set of suspension performance measures and three kinds of varying amplitude harmonic, rounded pulse and really measured random excitations are systematically defined, and the sensitivity of quarter-vehicle MR-suspension performance to variations in operating conditions is thoroughly analyzed. The results illustrate that the proposed skyhook-based semi-active MR-suspension in the asymmetric mode yields relatively superior dynamic responses to meet the multiple suspension performances of ride, rattle space, road-holding and dynamic tire force transmitted to the pavement, and has desirable robustness on variations in operating conditions of vehicle load and speed and the road roughness.

PI control based on fuzzy set-point weighting tracking for hydraulic crane boom system

A PI control strategy based on fuzzy set-point weighting following was proposed for the active damping control of a hydraulic crane boom system （HCBS）. Two valve-controlled PI controllers, which include a proportional feedforward controller based on fuzzy set-point weighting following and a limited semi-integrator（LSI）, are designed respectively. LSI is used to limit output signal and to prevent wind up at the low frequency of the spectrum. By using a range camera and an electronic feedback control, the tip damping on the HCBS can be adjusted artificially. A collaborative control simulation technique of HOPSAN and MATLAB/SIMULINK is applied to the controller design. Simulation results show that the proposed PI control system has less overshoot as well as faster response. The tip damping on the HCBS during operation is improved.

悬索桥竖弯涡振MTMD减振控制效果和参数优化研究

为研究多重调谐质量阻尼器(Multiple Tuned Mass Damper,MTMD)抑制桥梁单阶涡振的性能,建立桥梁结构-MTMD系统竖弯涡振广义单自由度动力方程,以某大跨度悬索桥为背景进行MTMD减振控制效果和参数优化分析。采用数值方法求解动力方程,获得系统在简谐涡激力下达到稳态谐振时结构的动力放大系数和MTMD对结构的附加模态阻尼比,并与单一频率调谐质量阻尼器(Single Tuned Mass Damper,STMD)的减振控制效果进行对比,然后以附加模态阻尼比为目标对MTMD进行参数优化。结果表明:MTMD比最优参数STMD拥有更宽的控制频带和更好的减振效果,经优化后的MTMD减振性能优于最优参数STMD。实际应用MTMD时,应选择较大广义质量、5~7种频率规格,并根据二者找到无量纲频率范围和各TMD阻尼比的惟一最优取值。

基于分数阶的空气弹簧建模及电动汽车主动悬架控制研究

电控空气悬架系统(electrically controlled air suspension, ECAS)具有调节悬架刚度和车身高度的功能,可有效改善车辆乘坐舒适性和操纵稳定性。以某乘用车ECAS为对象,利用分数阶理论描述橡胶气囊的黏弹性阻尼特性,考虑等效阻尼及滞回特性对其热力学模型进行了优化,结果与实验数据吻合良好,验证了优化后的空气弹簧模型的精确性。在此基础上,考虑车辆纵横向动力学特性与Dugoff轮胎模型,建立14自由度整车ECAS动力学模型,提出模型预测(model predictive control, MPC)主动悬架控制方法,以可测变量为控制器输入,实现直线及转向行驶工况下的主动控制。仿真与整车台架实验研究表明,分数阶修正模型可以很好地反映ECAS变刚度特性,基于MPC的主动悬架控制策略能实时调整空气弹簧刚度,控制车身姿态,有效改善电动汽车行驶时的平顺性与稳定性。论文的研究方法为车辆悬架系统建模及主动控制提供了一种新思路。

高机动越野平台非线性悬挂特性控制方法

为了提升装备机动能力,基于摆动缸式油气悬挂装置,建立高压气动原理和背压可控的阻尼阀结构,实现刚度和阻尼特性的实时调节。基于单轮悬挂模型开展不同刚度控制方法的振动响应对比分析以及阻尼特性频域不动点推导,提出一种刚度有级调节控制策略和一种频域混合阻尼控制方法,通过单轮悬挂动力学模型验证所提控制方法的有效性,并构建高机动履带车辆动力学模型进行整车仿真分析。在康庄、羊八井、坨里实测路面环境下,采用刚度阻尼联合控制方法的悬挂装置相较于传统被动悬挂的越野速度提升了25%以上,验证了新提出特性控制方法对振动响应抑制的优越性,能够为悬挂装置实现弹性与阻尼双特性自适应调节提供支撑。

铁路悬索桥车致纵向运动混合阻尼减振研究

针对铁路悬索桥在列车过桥时梁端纵向运动响应控制问题,提出了一种创新的混合阻尼减振方案,采用多种类型的阻尼器控制梁端位移,以满足不同的减振需求.以某在建大跨铁路悬索桥为工程背景,建立了空间桁架精细模型和等效单梁简化模型,系统研究了混合阻尼减振方案不同阻尼器参数对减振效果的影响.该方案将低指数黏滞阻尼器纵向安装于桥塔与加劲梁之间,同时在桥台与加劲梁之间纵向安装电涡流阻尼器.鉴于桥台结构的特殊性,电涡流阻尼器被设计为仅能承受压力的装置,并通过样机试验进行了验证.为了进一步提升减振性能,电涡流阻尼器还配备了摩擦耗能元件.该混合阻尼减振方案能够有效控制列车过桥时梁端的纵向运动响应,显著提高桥梁结构的安全性和耐久性,在类似工程中具有重要的参考价值和借鉴意义.

基于附加阻尼的水轮机调速系统优化控制研究

针对水轮机调速系统引发电力系统发生超低频振荡的问题,提出一种调速侧附加阻尼控制策略。首先,基于阻尼转矩法,分析得出水轮机调速系统产生的负阻尼是造成电力系统发生超低频振荡的主要原因;其次,推导调速系统的阻尼转矩系数表达式,证明该系数与水锤效应时间常数及调速器PID参数密切相关;然后,依托附加阻尼控制策略,在系统调速侧引入正阻尼补偿,并采用灰狼优化算法整定调速器PID参数,以进一步改善系统阻尼特性;最后,在Matlab/Simulink仿真平台搭建单机、四机两区域系统进行仿真验证,结果表明所提控制策略能够明显改善调速系统的阻尼特性,有效抑制超低频振荡。

四级阻尼可调式液压互联悬架系统性能研究

提出一种新型四级阻尼可调式液压互联悬架(FDAHIS)系统。FDAHIS系统在被动液压互联悬架系统的阻尼阀上并联了两个常通孔面积不同的电磁开关阀,通过反馈控制策略控制电磁阀开闭状态,调节系统液压流量,从而实现阻尼四级可调。为了研究该系统性能,建立FDAHIS系统模型和七自由度整车模型。通过系统单元台架试验对该模型进行了验证。整车仿真结果表明,与被动的液压互联悬架(HIS)系统相比,FDAHIS系统在车辆行驶平顺性和抗俯仰性能方面表现更佳。

外部冲击下的液压阻尼作动器位置控制策略研究

为了提高液压伺服系统在外部负载突变时的控制性能,提升核心元件和传感单元的使用寿命,创新提出液压作动器与磁流变阻尼器串联的液压阻尼作动器,以实现主动阻尼补偿。首先,针对系统的抗冲击需求,定制开发了多级堆叠式流道结构的磁流变阻尼器,并将其与液压作动器串联组成液压阻尼作动器;然后,采用基于力内环和位置外环的阻尼补偿控制方法,且设计磁流变阻尼器与液压作动器的耦合控制器,确保液压作动器位移跟踪精度的同时快速抑制外部振动冲击;最后,构建位移激励和变负载冲击实验,活塞杆的综合位移控制精度提高了38%以上,验证了液压阻尼作动器在耦合控制器下具备良好的动态响应性能和冲击抑制效果。

悬吊多质量摆体系力学机理及减振性能试验研究

传统悬吊质量摆有悬吊单摆、串联式悬吊多摆和并联式悬吊多摆,这几种类型摆构造简单、机理明确,但调谐频带较窄,应用在低频率超高层结构下摆长过长、高频率高层结构下摆长过短,限制其在实际工程中的应用。为此,提出装有弹簧的串、并联式悬吊多摆结构,建立装有串、并联式悬吊多摆的结构体系动力学方程。为研究这两类悬吊摆的减振性能,通过数值模拟对比分析传统悬吊质量摆与装有弹簧的串、并联悬吊摆对受控结构的减振效果,并对受控结构与非受控结构进行一系列振动台试验,验证悬吊单摆、悬吊串、并联式无弹簧双摆、悬吊串、并联式弹簧双摆在传统地震动下以及四类场地地震动作用下对被控结构减振控制的有效性。数值模拟与振动台试验结果均表明,装有弹簧的串联式悬吊多摆减振效果最优,其具有增大调谐频带、实现多阶振型控制、灵活调节摆长的优点,适用于工程实际中。

基于磁流变阻尼器高速列车半主动座椅悬架控制方法对比研究

在建立了高速列车“座椅-车体-构架”三自由度模型系统基础,分别提出了基于磁流变阻尼器的MPC控制、天棚阻尼控制、模糊控制半主动控制策略,并进行仿真分析。研究结果表明:与被动控制相比,施加半主动控制后的座椅振动加速度均方根值均有所减小,其中采用天棚控制、模糊控制和MPC控制的座椅加速度均方根值分别减少了25.37%,17.67%和16.38%;从频域角度而言,三种控制方法都能降低座椅5 Hz频带内的振动幅值;虽然天棚阻尼控制对座椅5 Hz频带内的幅值降低最大,但同时会造成座椅5 Hz以上的振动幅值增加,而MPC和模糊控制方法对座椅5 Hz以上的振动幅值没有明显影响。

液力式惯容器管道阻尼设计研究

针对液力式惯容器相互耦合的惯容管道阻尼、惯容量和有效刚度等特性极大限制了其振动控制范围的问题,提出了一种全新蜿蜒式布局的惯容管道。基于液力式惯容器的工作机理,利用机械与液压网络类比法建立了蜿蜒式管道对应阻尼的数学模型,仿真验证了在惯容量和有效刚度恒定时,通过调节蜿蜒式管道的关键设计参数可实现一定程度的管道阻尼独立调节。此外,研制了蜿蜒式管道的液力式惯容器原型样机,试验验证了蜿蜒式管道阻尼的模型正确性以及原型样机的性能准确性。结果表明,蜿蜒式管道设计实现了管道阻尼与惯容量、有效刚度的物理解耦,拓宽了液力式惯容器的振动控制范围,为同类液力式减振设备的研发提供了一种切实可行的阻尼设计新思路。

基于互联与阻尼分配框架的电液伺服系统轨迹跟踪策略

在中大型挖掘机电液伺服系统中存在复杂耦合非线性、模型不确定性,以及外部载荷不确定性等因素,都会造成挖掘机轨迹跟踪误差大,导致电液伺服系统的动态性能差。针对这一问题,提出了一种基于互联和阻尼分配(IDA)框架的反演控制器,以提高挖掘机工作装置在挖掘任务中的跟踪性能,并加强其鲁棒性。首先,利用先导阀、阀控非对称缸和阀控非对称缸模型构建了电液伺服系统的状态空间模型,并进一步基于哈密顿理论将该状态空间模型构造为具有扰动的三阶开环端口哈密顿系统(pH)。根据从pH系统中获得的互联矩阵和阻尼矩阵结构,逐步设计了虚拟控制信号,得到了控制律;然后,构造了一个匹配方程,以简化在其他系统上的设计和计算过程,并将期望的能量函数作为候选李雅普诺夫函数,根据李雅普诺夫稳定性定理证明了闭环系统在期望轨迹上的收敛性和稳定性;最后,以挖掘机铲斗及其电液伺服系统为对象,采用数值仿真实验验证了基于IDA框架的反演控制算法的轨迹跟踪性能。研究结果表明:在不考虑模型不确定性的情况下,所提出的控制器与其他三种控制器相比,在位置控制上的收敛速度可提高1.9%~6.3%;在轨迹跟踪上可保持优秀的收敛速度,且最大跟踪误差降低70%~81%;在模型不确定和时变负载的情况下,所提出的控制器与其他三种控制器相比,面对冲击时的最大跟踪误差仅增加0.004 m,调节所需控制输入降低4%~20%。这表明上述控制算法具有更优秀的综合跟踪性能和更强的鲁棒性。

测井绞车输出速度不足的原因分析与解决对策

由于液压泵的生产厂家修改了液压泵的HD阀设计,增加了阻尼孔,导致了控制HD阀压力出现损失,加之绞车的控制胶管过长(10 m),控制油在传递过程中产生的压力损失过大,导致系统先导控制压力建压不足,通过改变控制电路和降低马达先导控制压力,增加绞车输出速度。