基于免疫动态优化策略分层的电子控制空气悬架鲁棒控制系统设计方法

Electronically Controlled Air Suspension system (ECAS) has caused extensive concern with such advantages as low natural frequency, automatic switching of body height and suspension parameters. However, it still has choke points: car body vibrates in height switching, dynamic characteristics is hard to match, and control instability is apt to occur. To solve these problems, a series of studies are conducted. Body lift model is built. Relationship between body height and load is studied. Relationship between body height and gas mass in spring is studied as well. A new mechanism for height adjustment is proposed taking the gas mass in spring as observed quantity. ECAS dynamic model is built to study the relationship between load and spring stiffness as well as that between gas volume and spring stiffness. The relationship between orifice and shock absorber damper is studied. Theoretical system for using gas volume to regulate spring stiffness and using orifice to regulate shock absorber damper is constructed. Based on artificial immune algorithm, how to optimize vehicle suspension parameters is studied. Immune dynamic optimization strategy of ECAS suspension parameters is proposed. Perturbation, external disturbance and nonlinear ECAS nominal model are reconstructed. The new model is feedback linearized by feedback function and coordinate conversion. Control stability problem is transferred into robust issue. Design method of ECAS robustness controller is studied by applying μ theory. Taking body height and suspension parameters as output, ECAS robust controlling system is designed on the basis of immune dynamic optimization strategy hierarchical structure. The upper controller optimizes suspension parameters while the lower controller regulates the actuator. The research results of this project has important theoretical significance and application value to promote the Chinese level of ECAS Technology.

电子控制空气悬架（ECAS）具有自振频率低、车身高度及悬架参数可主动调控等优点，是汽车界的关注热点。但还存在车身高度切换易振荡、特性匹配难及参数摄动等现象。针对这些现象开展研究：建立车身升降模型，探讨车身高度与载荷、弹簧内气体量的关系，提出以气体量为观测量的车身高度调节新机制；建立ECAS动力学模型，研究载荷及气体容积与弹簧刚度、节流孔与减振器阻尼的关系，构建以工质容积调节刚度、节流孔调节阻尼的理论体系；基于免疫算法研究悬架参数优化问题，提出ECAS悬架参数免疫动态优化策略；用非线性不确定系统来描述不确定、有界的非线性ECAS模型，通过反馈函数及坐标变换反馈进行线性化，把控制稳定性问题转化为鲁棒性问题求解，引入μ理论研究鲁棒控制设计方法。在理论研究基础上，提出基于免疫动态优化策略分层的ECAS鲁棒控制系统设计方法。本项目研究成果对促进我国ECAS技术水平的提高具有重要理论意义和应用价值。

与被动汽车悬架相比，电子控制空气悬架( ECAS)具有自振频率低、车身高度及悬架参数可主动调控等优点。针对ECAS仍存在的车身高度切换易振荡、特性匹配难及参数摄动问题。综合应该人工免疫算法、分层控制、鲁棒控制理论等探索改善ECAS控制系统性能的新理论和新技术，主要完成了下列研究内容：.1.建立了车身升降工况及ECAS垂向动力学模型.建立了车身高度变化与气体量的数学模型，将高度问题转化为气体量调控问题；建立了ECAS汽车系统动力学模7型，分析了路面条件和加速、匀速、制动及转向工况悬架参数影响整车性能的规律。为控制系统的控制策略研究及其设计、实现提供了理论模型。.2.ECAS悬架参数免疫动态优化策略研究.引入人工免疫算法，将悬架刚度及阻尼看成免疫系统的B细胞，而汽车综合性能视为抗体，最佳汽车性能看作抗原，为抗体编码并置初始值，循环计算亲和力来搜索最佳悬架刚度及阻尼，提出了ECAS悬架参数免疫动态优化策略。.3. ECAS系统的μ鲁棒控制策略研究.重构含不确定性及外扰的非线性ECAS汽车动力学模型，将其归为一类仿射不确定系统，通过模型线性化，应用μ分析与μ综合求解出鲁棒控制器，提出了ECAS系统鲁棒控制设计方法。.4. ECAS系统车载控制器设计开发.提出了分层的ECAS系统车载控制器架构，设计了具有车身升降及悬架参数动态优化功能的上层控制器，和具有鲁棒控制策略的下层控制器。.5.ECAS系统与整车的试验研究. 开发了ECAS系统的执行机构，设计了汽车性能的测试平台，测试了空气弹簧特性、减振器特性、控制器性能和ECAS汽车性能，分析了试验结果。.试验结果表明，ECAS汽车后排座垫总加权加速度均方根值位于0.315~0.63 m/s2范围内。表明，以气体质量为观测量可以解决车身升降震荡问题，免疫算法能动态优化出悬架特性，μ鲁棒控制策略能抑制模型参数摄动、未建模动态及外扰，提高了系统的稳定性和鲁棒性。