中文名稱： 基於磁流變阻尼器的車輛懸架系統半主動控制
英文名稱： The semi-active control of vehicle suspension systems based on magnetorheological dampers
摘要： 近年來，應用半主動控制懸架系統提高車輛的乘座舒適性和操縱穩定性的研究受到了學術界和工業界的廣泛關註。半主動控制懸架系統的關鍵之壹是可實時調節的阻尼器。實踐證明，磁流變阻尼器具有結構簡單、消耗功率小、抗汙染和輸出力大等優點，有可能在實際的半主動控制中得到應用。本文在對磁流變液體和磁流變阻尼器的研究基礎上，以磁流變阻尼器作為半主動控制元件組成磁流變阻尼半主動懸架系統。運用理論分析、數值仿真和試驗研究等方法對磁流變阻尼半主動懸架的動力學特性和半主動控制技術進行了研究。論文的主要貢獻如下：
通過測試磁流變液剪切應力與磁感強度、剪切應變速率、溫度的變化規律，建立了能反映磁流變液剪切變稀現象的剪切應力與剪切應變速率的磁流變液模型。根據磁流變液模型，從理論上建立了能在較寬的電壓內範圍比較準確地預報磁流變阻尼器輸出力的近似公式。通過對磁流變阻尼器的試驗研究，分析和得出了磁流變阻尼器輸出力呈現出非線性滯回和飽和特性。建立了磁流變阻尼器的等效剛度和等效粘性阻尼系數與施加電壓、激振頻率和振幅的關系以及能精確表示磁流變阻尼器的力學特性的非線性滯回模型。
從理論上分析了被動阻尼、“天棚”阻尼、“地棚”阻尼懸架系統的時域和頻域動力學特性。運用等效線性化方法，分析了懸架系統由磁流變阻尼器而引起的非線性動力學特性。應用Lyapunov方法分析了磁流變阻尼半主動控制懸架自由振動的漸近穩定性。
根據磁流變阻尼器特性和對懸架系統動力學特性的規律性研究，為磁流變阻尼器設計了基於“天棚”阻尼控制概念的“on-off”、線性連續和修正的線性連續控制策略，基於“地棚”阻尼控制概念的磁流變阻尼線性連續控制策略，“天棚”阻尼和“地棚”阻尼控制概念線性組合起來的磁流變阻尼混合控制策略，根據模糊控制原理設計了以簧載質量和非簧載質量間相對位移或簧載質量加速度分別作為輸入變量的模糊邏輯控制器用於磁流變阻尼半主動懸架的智能控制。建立了應用Matlab〓+Simulink〓+Fuzzy Toolbox軟件編制的磁流變阻尼半主動懸架仿真系統，通過數值仿真分析了磁流變阻尼半主動控制懸架在不同模擬路面輸入條件和控制策略下的時間響應特性和頻率特性。
設計並實現了磁流變阻尼半主動懸架測控試驗系統。應用模擬懸架測控系統成功地完成了磁流變阻尼半主動控制懸架在不同模擬路面輸入條件和控制策略下的時間響應特性和頻率特性的測試。試驗結果表明，本文設計的控制算法均可對磁流變阻尼半主動控制懸架不同程度地實現有效的控制。特別是模糊控制算法，僅需要單個傳感元件就能對磁流變阻尼半主動懸架實現很有效的控制。從理論分析、仿真分析和試驗結果分別得到的磁流變阻尼半主動控制懸架的時間響應特性和頻率特性及其規律性是基本壹致的。
Abstract
At present, semi-active control suspension systems have received a great deal of attention in academe and industrial circles to improve ride comfort and road holding and handling stability. The damper with dynamically variable damping properties is one of the key elements for semi-active suspension systems. Magneto-rheological (MR) fluid dampers have recently emerged as enabling technology for implementing semi-active control in a variety of application because of their mechanical simplicity, low operating power requirements, environmental robustness, and demonstrated potential for developing forces sufficient for applications. MR dampers use MR fluids with a change in rheological behavior when a magnetic field is applied to produce controllable damping. In the dissertation, a state-of-the-art semi-active control suspension system in which the MR dampers are used to replace the passive dampers as the semi-active control actuators has been proposed and developed based on the analytical and experimental investigations of the MR fluid and the MR damper. The theoretically analytical, simulation and experimental investigations are conducted to characterize the dynamical performance and to develop the semi-active control technology of the MR damping semi-active suspension system. The main contributions of the dissertation are as follows:
On the basis of experimental results, the operational effects, such as the magnitude of magnetic field, the temperature and the rate of shear strain, on the shear stress of the MR fluid are shown and models of the quasi-Bingham model and a nonlinear model for the shear stress of the MR fluid also are developed, in which the characteristic of"shear-thin"of the MR fluid is described. The approximate equation is established to calculate accurately the output force of the MR damper based on the developed MR fluid model by the theoretically analytical investigations. This dissertation also presents the equivalent stiffness and damping models and the nonlinear hysteresis and saturation model of a kind of the MR damper developed by the experimental testing and modeling in order to describe accurately characteristics of the MR damper. In addition, the operational effects, such as the magnitude of voltage (the magnitude of the magnetic field) , the amplitude and frequency of excitation, on the parameters of the models are discussed according to the experimental results.
The theoretical investigations are carried out in two phases. In phase 1, the dynamical properties in the time and frequent domains of the simple, two-degreeof-freedom models of passive, "sky-hook"and"ground-hook"damping suspension systems are examined by Laplace transform. In phase 2, the nonlinear dynamical properties of the simple, two-degree-of-freedom model of MR damping suspension systems are explored by the method of equivalent linearization. The asmptotic stability of the free vibration for the MR damping semi-active suspension system is determined by the Lyapunov stability theory.
Several semi-active control algorithms used in the semi-active suspension system with MR dampers are proposed and developed including the"on-off" voltage controller, the continuously linear variable voltage controller, the modulated continuously linear variable voltage controller based on"sky-hook"damping concept and the hybrid controller based on the combination of"sky-hook"damping concept and"ground-hook"damping concept and the Fuzzy logic controllers using measurements of the relative displacement between the sprung and unsprung mass or the absolute acceleration of the sprung mass as the input variables of fuzzy logic controllers. The simulation models were prepared in Matlab〓+Simulink〓+Fuzzy toolbox programs. The experiment setup of the semiactive suspension system with MR dampers in the lab has been designed and developed. The effectiveness of the proposed the semi-active suspension system with MR dampers is successfully verified by evaluating the dynamical characteristics of different semi-active control algorithms for the semi-active suspension system with MR dampers in time and frequency domains through the numerical simulation investigations and the lab tests under various road excitations. Each proposed semi-active algorithm resulted in improvements in performance of ride comfort and road holding and handling stability in some way. The test results show specially that both of fuzzy logic algorithms possess the flexibility to allow the control designer to adjust the control rules to much more effectively improve the control objectives and only one sensor is needed to measure the control signal for reducing cost. The experimental results of the dynamical characteristics of the semi-active suspension system with MR dampers in time and frequency domains are consistent with the results of the theoretically analytical and simulation investigations