Hierarchical Control of Ride Height System for Electronically Controlled Air Suspension Based on Variable Structure and Fuzzy Control Theory

The current research of air suspension mainly focuses on the characteristics and design of the air spring. In fact, electronically controlled air suspension(ECAS) has excellent performance in flexible height adjustment during different driving conditions. However, the nonlinearity of the ride height adjusting system and the uneven distribution of payload affect the control accuracy of ride height and the body attitude. Firstly, the three-point measurement system of three height sensors is used to establish the mathematical model of the ride height adjusting system. The decentralized control of ride height and the centralized control of body attitude are presented to design the ride height control system for ECAS. The exact feedback linearization method is adopted for the nonlinear mathematical model of the ride height system. Secondly, according to the hierarchical control theory, the variable structure control(VSC) technique is used to design a controller that is able to adjust the ride height for the quarter-vehicle anywhere, and each quarter-vehicle height control system is independent. Meanwhile, the three-point height signals obtained by three height sensors are tracked to calculate the body pitch and roll attitude over time, and then by calculating the deviation of pitch and roll and its rates, the height control correction is reassigned based on the fuzzy algorithm. Finally, to verify the effectiveness and performance of the proposed combined control strategy, a validating test of ride height control system with and without road disturbance is carried out. Testing results show that the height adjusting time of both lifting and lowering is over 5 s, and the pitch angle and the roll angle of body attitude are less than 0.15?. This research proposes a hierarchical control method that can guarantee the attitude stability, as well as satisfy the ride height tracking system.     

Adaptive backstepping-based tracking control design for nonlinear active suspension system with parameter uncertainties and safety constraints

This paper proposes a novel constraint adaptive backstepping based tracking controller for nonlinear active suspension system with parameter uncertainties and safety constraints. By introducing the virtual control input and reference trajectories, the adaptive control law is developed to stabilize both of the vertical and pitch motions of vehicle body using backstepping technique and Lyapunov stability theory, and further to track the predefined reference trajectories within a finite time, which not only ensure the safety performance requirements, but also achieve improvements in riding comfort and handling stability of vehicle active suspension system. Next, the stability analysis on zero dynamics error system is conducted to ensure that all the safety performance indicators are all bounded and the corresponding upper bounds are estimable. Finally, a numerical simulation is provided to verify the effectiveness of the proposed controller and to address the comparability between the classical Barrier–Lyapunov Function based adaptive tracking controller and the proposed controller.     

A hybrid approach to modeling and control of vehicle height for electronically controlled air suspension

The control problems associated with vehicle height adjustment of electronically controlled air suspension (ECAS) still pose theoretical challenges for researchers, which manifest themselves in the publications on this subject over the last years. This paper deals with modeling and control of a vehicle height adjustment system for ECAS, which is an example of a hybrid dynamical system due to the coexistence and coupling of continuous variables and discrete events. A mixed logical dynamical (MLD) modeling approach is chosen for capturing enough details of the vehicle height adjustment process. The hybrid dynamic model is constructed on the basis of some assumptions and piecewise linear approximation for components nonlinearities. Then, the on-off statuses of solenoid valves and the piecewise approximation process are described by propositional logic, and the hybrid system is transformed into the set of linear mixed-integer equalities and inequalities, denoted as MLD model, automatically by HYSDEL. Using this model, a hybrid model predictive controller (HMPC) is tuned based on online mixed-integer quadratic optimization (MIQP). Two different scenarios are considered in the simulation, whose results verify the height adjustment effectiveness of the proposed approach. Explicit solutions of the controller are computed to control the vehicle height adjustment system in realtime using an offline multi-parametric programming technology (MPT), thus convert the controller into an equivalent explicit piecewise affine form. Finally, bench experiments for vehicle height lifting, holding and lowering procedures are conducted, which demonstrate that the HMPC can adjust the vehicle height by controlling the on-off statuses of solenoid valves directly. This research proposes a new modeling and control method for vehicle height adjustment of ECAS, which leads to a closed-loop system with favorable dynamical properties.     

调距桨液压双阀控制系统设计与分析

针对比例方向阀与电液换向阀组成的调距桨液压双阀并联控制回路进行理论分析,提出了液压双阀系统控制策略,确定了控制器参数,并在AMESim软件中对控制系统性能进行仿真分析。计算结果表明控制策略与参数设计合理,满足调距桨桨距调节性能要求。     

基于滑模变结构理论的车辆主动横向稳定杆控制

为实现对车辆的侧倾控制,自主设计了主动横向稳定杆（AARB）装置。针对车辆在侧倾中存在的非线性、时变性特点,采用滑模变结构控制理论建立了滑模控制器从而实现对理想侧倾角的跟踪,并采用鱼钩与双移线转向工况进行了仿真试验。仿真结果表明,该主动横向稳定杆装置与传统被动横向稳定杆装置相比,能有效减小车辆的侧倾,同时具有良好反馈特性以,有利于驾驶员对车身姿态的判断,从而大大提高了车辆行驶的安全性与乘坐舒适性。     

随机干扰下汽车电控悬架车身高度控制研究

空气悬架汽车在对其车身高度进行动态切换的过程中会严重受到随机干扰所带来的不良影响,为了解决这个问题,通过与空气弹簧的模型结合而建立整车模型,从而对随机干扰下汽车电控悬架车身高度的调节和控制进行研究。其中神经网络PID自适应高度调节控制器是利用单神经元自调整增益算法来设计的,并通过仿真软件对控制器的性能进行验证。根据仿真结果可验证所设计的控制器能够有效改善随机干扰对汽车电控悬架车身高度调节过程中产生的震荡,并使得车辆的稳定性和舒适性得到了提高。     

并联六轮腿机器人机身平稳性控制方法研究

轮腿式机器人在非结构化路面运动时,机身平稳性控制对于提高运动平稳性、降低系统能耗、提高定位与建图精度等具有重要意义。针对并联式六轮腿机器人在通过不规则地形时足端悬空、姿态倾斜、机身晃动等问题,提出一种融合足端力控制器、姿态控制器及重心高度控制器的机身平稳性控制框架。其中,足端力控制器通过阻抗控制算法抑制机器人足端受力因地形变化带来的突变扰动;机身姿态控制器对机身倾斜角进行解耦,并控制各腿的长度补偿机身的偏移量;重心高度控制器根据各腿的伸长量自适应地调节机身高度,保证腿部执行机构具有足够的运动空间。针对三种控制器相互耦合、对外部扰动抑制效果不佳等问题,利用串级控制的思想将三种控制目标统一为力跟踪控制,降低机身振荡的风险。在并联式六轮腿机器人上进行了实验验证,结果表明所提出的控制算法框架能有效抑制外部地形扰动,当机器人以大约0.6 m/s的速度前进时,机身的俯仰角及横滚角保持在-0.7°~0.7°范围内,足端接触力维持在期望力附近,且机身重心高度随地面起伏自适应地调整,确保了机器人的运动平稳性。     

基于整车转向模型的汽车主动悬架控制研究

针对汽车主动悬架系统在转向过程中的动力学行为，建立了整车转向模型。从提高汽车转向时的乘坐舒适性和操纵稳定性出发，从时域和频域两方面研究了整车系统的最优控制问题。考虑转向过程中汽车的横摆、侧倾、俯仰及垂直方向的振动和悬架的动挠度，定义了范数评价指标，并根据人体对振动的敏感频率范围引入了适当的频域加权函数，设计出最优控制器。仿真结果表明，该方法能够有效抑制由转向和路面不平引起的振动，明显降低人体敏感频段的垂直和旋转方向振动的幅值，使悬架动挠度有所下降。     

汽车磁流变半主动悬架仿人智能控制研究

在建立整车动力学模型的基础上，设计了基于整车分姿态协调控制的仿人智能控制器。将汽车看成快速移动的机器人，把汽车运动姿态划分为八种姿态，对不同的运动姿态采用不同的控制模态，并在MATLAB平台上进行了仿真。选用某型号轿车作为试验车辆，用磁流变半主动悬架替代原车被动悬架，在多种条件下进行了实车道路试验，试验结果与仿真结果吻合，表明对整车进行分姿态协调控制是可行的。与被动悬架相比较，仿人智能控制可提高平顺性能近20％，能有效抑制车身的俯仰和侧倾运动，改善轮胎的接地性能，其控制效果优于对各悬架进行独立控制的天棚控制策略。     

Research on the effects of coordinate deformation on radial-axial ring rolling process by FE simulation based on in-process control

The boundary layer approach is the most popular method to reduce the chattering phenomenon in sliding mode control (SMC) for uncertain nonlinear systems. This paper applies the fuzzy sliding mode structure based on the boundary layer theory which is used as speed controller of an indirect field-oriented control (IFOC) of an induction motor (IM) drive. A fuzzy inference system is assigned for reaching the controller part of the fuzzy sliding mode controller (FSMC) to eliminate the chattering phenomenon in spite of the small and large uncertainties in the system. The applied fuzzy system acts like a saturation function technique in a thin boundary layer near the sliding surface so that the stability of the system is guaranteed. Also, the equivalent control part is estimated to avoid the computational burden by an averaging filter. On the other hand, the averaging filter assists to improve the tracking performance despite the possibility of large uncertainties in the system so that the stability of the system is guaranteed. The main advantages of the proposed chattering-free speed controller are robustness to parameter variations and external load disturbance. The simulation results are shown to verify the effectiveness of the proposed speed controller, and its advantages are shown in comparison with the FSMC system and the conventional SMC.     

基于模糊PID的车辆侧倾主动控制仿真研究

在ADAMS/Car下,建立了前后悬架都装有主动横向稳定杆的95自由度虚拟整车模型.采用模糊自适应PID控制策略,在Matlab/Simulink环境中对车辆抗侧倾性能进行了联合仿真,实现了PID控制过程中参数的在线整定.仿真结果表明,模糊自适应PID控制具有较强的自适应和抗干扰能力,有效地减小了车身侧倾角,在保证乘坐舒适性的同时提高了车辆的行驶稳定性.     

Observation of Slider Landing Process in Hard Disk Drive

With the decrease in slider flying height, slider flying instability caused by slider–disk interactions is becoming a big concern. Novel technology has to be employed to further improve our understandings about slider–disk interaction. In this work, a slider flying height-attitude testing (3D) system was employed to study slider–disk interaction during a slider landing process to demonstrate its capability for the application. It is shown that great details of slider–disk interactions and subtle variations of the slider flying attitude during the landing process can be revealed with the 3D system. Slider dynamic flying height and attitude (pitch and roll angles) during the landing process can be determined from the data recorded in one test. Furthermore, analysis in frequency domain can be done not only on flying height, but also on pitch and roll angles directly. It is found that the slider landing process can have different stages during which slider performance and characteristics of slider–disk interaction are different.     

Robust control of nonlinear integrated ride and handling model using magnetorheological damper and differential braking system

The interaction of the ride and handling systems is one of the challenging topics in vehicle dynamics and control. In this study the dynamic behavior of a passenger car considering coupling among all the fourteen degrees of freedom is modeled using Boltzmann Hamel equations. In order to improve the ride quality and stability of the vehicle, a Magnetorheological damper and a differential braking system are used as control devices. Based on the nonlinear integrated ride and handling vehicle model, a nonlinear H-infinity controller is designed for an intermediate passenger car. The dynamic behavior of the controlled vehicle is simulated for single lane change and bump input, considering three different road conditions: Dry, rainy and snowy. The robustness of the designed controller is investigated when the vehicle is under these road conditions. The simulation results confirm the interactive nature of the ride and handling systems and the robustness of the designed control strategy.     

自适应模糊控制半主动悬架系统的研究

半主动悬架系统自适应模糊控制器的应用是为了提高汽车悬架的阻尼效果和操控性。建立 4自由度 1 /2车辆模型 ,在此模型基础上 ,设计了模糊控制器 ,论述了半主动悬架系统的模糊控制方法 ,说明此方法对悬架质心加速度、轮胎动载荷和悬架俯仰角等性能的提高有益。对悬架在各种输入激励下的仿真效果与被动悬架作了比较 ,结果令人满意。     

Verification of intelligent control of a launch vehicle with HILS

The reliability of an intelligent self tuning controller called the brain emotional learning based intelligent controller (BELBIC) to attitude control of a nonlinear launch vehicle (LV) simulation with hardware-in-the loop simulation (HILS) is studied. To set up the HIL system of the LV a six-degree of freedom simulation of the LV and a hydraulic actuator, which was used for the pitch channel thrust vector control (TVC) actuator of the LV, is performed. The results of the BELBIC controller with a fuzzy controller (FC) and a PID controller in this HILS of the LV to control the pitch channel of the LV have been compared.     

高处作业悬吊平台的智能调平系统

研究了采用追求同一方向策略的1种新颖高处作业悬吊平台智能调平系统,提高了高处作业悬吊平台在调整精度和速度方面的性能,使平台在安全,智能自动控制中显出更高的优越性.可编程控制器(PLC)和双轴倾角传感器用于控制系统,该系统会根据高处作业悬吊平台的倾角自动更改提升机的动作,以迅速实现调平操作,并可以实现多点高处作业悬吊平台驱动±2°的准确性,调整时间少于5 s.对该系统的控制策略以及微机系统的硬件配置进行了描述.此外,还对干扰信号的影响及不同的消除颤振的时间做了评估.     

Hybrid control of an active suspension system with full-car model using H∞ and nonlinear adaptive control methods

This paper presents hybrid control of an active suspension system with a full-car model by using H_∞ and nonlinear adaptive control methods. The full-car model has seven degrees of freedom including heaving, pitching and rolling motions. In the active suspension system, the controller shows good performance: small gains from the road disturbances to the heaving, pitching and rolling accelerations of the car body. Also the controlled system must be robust to system parameter variations. As the control method, H_∞ controller is designed so as to guarantee the robustness of a closed-loop system in the presence of uncertainties and disturbances. The system parameter variations are taken into account by multiplicative uncertainty model and the system robustness is guaranteed by small gain theorem. The active system with H_∞ controller can reduce the accelerations of the car body in the heaving, pitching and rolling directons. The nonlinearity of a hydraulic actuator is handled by nonlinear adaptive control based on the back-stepping method. The effectiveness of the controllers is verified through simulation results in both frequency and time domains.     

Steering error optimization of the Macpherson strut automotive front suspension

A vehicle model is developed employing a detailed nonlinear kinematic representation of a MacPherson strut front independent automotive suspension with a rack and pinion steering system. The vehicle model is capable of front wheel steering motions as well as vehicle body rolling motions. The vehicle model is used to simulate steady-state turning maneuvers on a smooth, flat road. The model is employed in conjunction with a realistic set of constraints to optimize a representative suspension and steering system with respect to steering error for turn radii and body roll angles typical of highway driving. Improved suspension and steering geometries are presented for two optimization studies.     

Skyhook-based semi-active control of full-vehicle suspension with magneto-rheological dampers

The control study of vehicle semi-active suspension with magneto-rheological (MR) dampers has been attracted much attention internationally. However, a simple, real time and easy implementing semi-active controller has not been proposed for the MR full-vehicle suspension system, and a systematic analysis method has not been established for evaluating the multi-objective suspension performances of MR full-vehicle vertical, pitch and roll motions. For this purpose, according to the 7-degree of freedom (DOF) fullvehicle dynamic system, a generalized 7-DOF MR and passive full-vehicle dynamic model is set up by employing the modified Boucwen hysteretic force-velocity (F-v) model of the MR damper. A semi-active controller is synthesized to realize independent control of the four MR quarter-vehicle sub-suspension systems in the full-vehicle, which is on the basis of the proposed modified skyhook damping scheme of MR quarter-vehicle sub-suspension system. The proposed controller can greatly simplify the controller design complexity of MR full-vehicle suspension and has merits of easy implementation in real application, wherein only absolute velocities of sprung and unsprung masses with reference to the road surface are required to measure in real time when the vehicle is moving. Furthermore, a systematic analysis method is established for evaluating the vertical, pitch and roll motion properties of both MR and passive full-vehicle suspensions in a more realistic road excitation manner, in which the harmonic, rounded pulse and real road measured random signals with delay time are employed as different road excitations inserted on the front and rear two wheels, by considering the distance between front and rear wheels in full-vehicle. The above excitations with different amplitudes are further employed as the road excitations inserted on left and right two wheels for evaluating the roll motion property. The multi-objective suspension performances of ride comfort and handling safety of the proposed MR full-vehicle suspensi