【作者】 汪洪波；

【导师】 陈无畏；

【作者基本信息】 合肥工业大学 ， 车辆工程， 2014， 博士

【摘要】 汽车是重要的载运工具之一，与人们的生产生活联系最为密切。底盘作为汽车的重要总成之一，对改善汽车的乘坐舒适性、操纵稳定性和安全性等性能具有重要作用。底盘系统由悬架、转向和制动等子系统构成，对其施加主动控制作用可以改善汽车的某方面的性能。由于其子系统之间存在相互耦合，对底盘集成系统的优化控制带来了困难，研究者所设计的控制系统均能从某些方面改善底盘系统的控制性能。如何考虑各子系统间功能区别，对底盘集成系统各子系统进行功能分配且协调控制系统设计，保证底盘全局控制系统性能最优，是当前研究的难点。本文针对汽车底盘系统的悬架、转向和制动三个子系统间耦合作用，展开系统建模、子系统控制器设计和高阶悬架控制器模型降阶、基于功能分配的集成系统协调优化控制和稳定性分析等方面的研究，并进行了硬件在环仿真试验研究。具体为如下几个方面。1）针对整车悬架系统控制器阶数高、工程上难以实现的问题，建立整车7自由度主动悬架模型，基于最小信息损失模型降阶方法对20阶主动悬架控制器进行降阶研究，通过对降阶前后主动悬架闭环控制系统频域仿真和乘坐舒适性分析表明，20阶主动悬架控制器阶数能够被大大降低且系统状态能控能观信息损失不大。2）在建立汽车悬架与转向耦合动力学系统模型的基础上，选取偏差与偏差微分作为特征量，建立关于特征量的可拓集合。根据关联函数，划分经典域、可拓域、非域三种测度模式。在不同可拓集合范围内对控制功能进行分配，分别设计对应功能控制算法，构建基于功能分配的可拓控制器。通过仿真研究结果表明，基于功能分配的可拓控制可进一步全面提高悬架和转向集成系统的控制性能。3）对参数不确定性和时滞的系统，给出了系统稳定的充分性条件，并对悬架和转向系统进行了稳定性分析。在不同控制方法下，以悬架、转向系统参数作为变量，对集成控制系统的稳定性进行分析。结果表明，采用可拓控制，控制系统稳定性更佳；增大悬架阻尼、车速、前轮转向角至一定值时，汽车时域响应不稳定程度增加；改变可拓控制器偏差控制系数，对集成控制系统性能均有不同程度的影响；不断增加可拓控制器功能控制系数，系统各项控制性能会发生突变而失去稳定性。4）针对悬架与转向非线性集成系统，基于偏差分离的双线性控制、H∞控制、滑模变结构控制设计了非线性控制器，基于模糊规则的人车功能分配模块协调悬架和转向系统控制输出权重。通过仿真验证了双线性控制较H∞控制、滑模变结构控制，能更好地改善汽车乘坐舒适性和操纵稳定性能，同时体现了人车功能分配模块对进一步提升集成系统控制性能的有效性。5）针对汽车底盘悬架、转向、制动子系统耦合动力学关系，对悬架子系统设计非线性H∞控制器，对转向子系统设计直接横摆力矩PID控制器，对制动子系统设计滑模变结构控制器。基于功能分配原理对子系统控制功能进行分配，采用博弈论对子系统控制功能指标进行博弈，模糊规则实时自整定子系统控制器输出量以跟踪期望控制目标。对整车协调控制系统进行仿真,结果表明基于博弈论的整车协调控制系统较子系统单独控制、不加控制时能取得更好的控制性能。6）基于NI Compact-cRIO设计了硬件在环仿真试验平台，进行了悬架子系统、转向子系统和悬架与转向集成系统的硬件在环仿真试验，验证了所设计的可拓控制器和双线性控制器对改善汽车乘坐舒适性和操纵稳定性的有效性。在此基础上，采用Compact-cRIO9025在三种不同工况下，进行了基于快速原型的实车试验，进一步验证了所设计的双线性控制器的有效性。更多还原

【Abstract】 Vehicle is one of the important means of transport, which is most closely related topeople’s production and life. The chassis as one of the important vehicle assembly, playsan important role in improving vehicle ride comfort, handling and security performance.The chassis is composed of suspension, steering and braking subsystems. Applying theactive control to them can improve vehicle certain aspects of performance. Due to thecoupling relation among the subsystems, the optimal control to chassis integratedsystem is difficult. The designed control system can improve the chassis system controlperformance from some aspects. But how to consider the function difference of differentsubsystems, carry out the function allocation to the chassis integrated system’ssubsystems and design coordinated control system to guarantee the chassis with thewhole-region optimal control performance, is the difficulty of the current research.In this thesis, the coupled dynamics among the chassis’ three subsystems ofsuspension, steering and braking is considered. The research is on system modeling,subsystems’ controller design and order reduction for high-order suspension controller,integrated system corordinated control and optimization based on function allocation,and stability analysis. And the hardware-in-loop simulation is carried out to verify thedesigned control method. The details are illustrateed as follows.1) To solve the problems of high-order and hard to engineering realization offull-vehicle suspension controller, the7degree-of-freedom full-vehicle activesuspension model is built. Based on the minimal information loss method, theorder-reduction of active suspension controller is studied. Through thefrequency-domain simulation and ride-comfort analysis to the full-order andreduced-order active suspension control systems, the research results demonstrate thatthe20th-order of active suspension controller can be significantly reduced, and systemstate controllability and observability information loss is less.2) Based on building the vehicle syspension and steering system coupled dynamicmodel, the deviation and deviation derivative are chosen as the characteristic quantities,and the extension set is established. The three measure modes of the classical domain,extension domain and non-domain are divided according to the correlation function.The control functions are allocated in different extension sets, and the correspondingcontrol algorithms are separately designed to form the function allocation based extension controller (FAEC). The simulation research results demonstrate that the FAECcan further improve the control performance of the suspension and steering integratedsystem.3) For the system with parameters uncertainty and time-delay, the sufficient conditionof system stability is given. And then the stability is analyzed for the suspension andsteering system. The integrated control system stability is analyzed when utilizing thesuspension and steering system parameters as the variables by different control methods.The analysis results show that adopting the FAEC, the control system is with betterstability. When increasing suspension damping, vehicle velocity and the front-wheelsteering angle to certain values, vehicle time-domain responses’ instability degreeincreases. And when changing the FAEC error weighted coefficients, it brings differentdegrees of influences to the integrated control system performance. If constantlyincreasing the extension controller function control coefficient, it leads the vehiclecontrol system to instability.4) For suspension and steering nonlinear integrated system, the bilinear control basedon deviation separation(BCDS),H∞control and sliding mode variable structurecontrol (SMVSC) are utilized to design the nonlinear controllers. The human-vehiclefunction allocation module(HVFAM) based on fuzzy rules is adopted to coordinate thesyspension and steering system control weights. The simulation results demonstrate thatthe BCDS can better improve vehicle ride comfort and handling performance thanH∞control and SMVSC. And the HVFAM can futher improve integrated system controlperformance.5) Considering the coupled dynamics among suspension, steering and brakingsub-systems in vehicle chassis, the sub-optimal controllers of nonlinearH∞control,direct yaw moment PID control and sliding mode control are separately designed for thesuspension, steering and braking subsystems. The subsystems’ control functions areallocated based on the function allocation principle, and the subsystem’s controlfunction indices are utilized for competing by game theory. The fuzzy rules are utilizedto adaptively adjust the subsystems’ control output in order to follow the whole-regioncontrol object. The considerable simulations are carried out for full-vehicle coordinatedcontrol system. The results demonstrate that the full-vehicle coordinated control systembased on game theory can obtain the best control performances than the uncoordinatedcontrol system and uncontrolled system.6) The hardware-in-loop simulation test(HILST) platform is designed based on NI Compact-cRIO. The HILST for vehicle suspension subsystem, steering subsystem andintegrated system are carried out, to varify that the designed extension controller andbilinear controller can futher improve vehicle ride comfort and handling. Then thevehicle test based on rapid prototyping is carried out by adopting Compact-cRIO9025under three different conditions. And the test results also demonstrate the designedbilinear controller can obtain the best vehicle ride comfort and handling performance.更多还原