Hydraulic Servo-Mechanisms with Nonlinear Mechanical Loads: Robust Performance with Analysis and Control of Bifurcation Behavior

具有非线性机械负载的液压伺服机构：分岔行为分析和控制的鲁棒性能涉及液压伺服机构的运动和力控制系统（如活塞和杆执行器）是国家制造业，运输业和民用基础设施的重要组成部分。然而，液压驱动所提供的优势伴随着显著的非线性动力学形式的惩罚；耦合力学系统的非线性往往使这种行为进一步复杂化。其他研究者最近的研究主要集中在非线性控制技术的应用上（例如，自适应控制，变结构控制）。在本项目中开发的范例是表征传统线性反馈控制器在实现具有特定非线性结构负载和特定操作条件的液压伺服机构的非线性鲁棒稳定性方面的有效性质和程度。研究计划总结如下：(1)开发线性鲁棒性能和鲁棒稳定性的反馈设计，有无反馈内回路液压伺服机构特性的线性化；(2)。主要通过分岔分析来检验非线性鲁棒稳定性；(3)。检查非线性系统的实际性能（通过仿真和实验方法）；(4)。对于特定的应用和操作条件，定义上述方法有效的可接受范围/限制。该项目的预期影响和意义在于开发更好的技术来设计简单的低阶控制器，这些控制器将产生定义良好的非线性稳定裕度和比通过自适应控制或类似技术可实现的更高带宽。这项工作的潜在应用将包括汽车和航空航天动力传动元件的控制，如制动器和离合器，机床和结构测试样品的硬件在环控制。

David F. Thompson, University of CincinnatiProposal No. 9978704Hydraulic Servo-Mechanisms with Nonlinear Mechanical Loads: Robust Performance with Analysis and Control of Bifurcation BehaviorMotion and force control systems involving hydraulic servo-mechanisms (such as a piston-and-rod actuator) represent vitally important components of the nation's manufacturing, transportation, and civil infrastructures. However, the advantages afforded by hydraulic actuation are accompanied by a penalty in the form of significant nonlinear dynamics; this behavior is often further complicated by coupled mechanical system nonlinearities. Recent studies by other investigators have focused primarily upon the application of nonlinear control techniques (e.g., adaptive control, variable-structure control). The paradigm which is developed in this project is to characterize the nature and degree to which conventional linear feedback controllers are effective in achieving nonlinear robust stability of hydraulic servo-mechanisms, with specific nonlinear structural loads, and under specific operating conditions. The research plan is summarized as follows: (1.) Develop feedback designs for linear robust performance and robust stability with and without feedback linearization of the inner loop hydraulic servo-mechanism characteristics; (2.) Check for nonlinear robust stability, primarily through bifurcation analysis; (3.) Check actual performance of the nonlinear system (via simulation and experimental methods); (4.) For specific applications and operating conditions, define the acceptable ranges/limits over which the aforementioned approach is valid. The expected impact and significance of the project lies in the development of better techniques for the design of simple, low-order controllers which would yield well-defined nonlinear stability margins and higher bandwidths than would be achievable through adaptive control or similar techniques. Potential applications of this work would lie the control of automotive and aerospace power transmission elements such as brakes and clutches, machine tools, and hardware-in-the-loop control of structural test specimens.