Positive Utilization of Nonlinearity of Fluid Control Systems

本研究是对流体控制系统的非线性特性进行积极利用的基础性研究。液压控制系统具有功率大、响应快等优点，但同时也具有很强的非线性，阻碍了现代线性控制理论的应用。大多数液压控制系统都是通过传统的PID控制方法来设计的，忽略了系统的非线性或将系统的运行限制在一个很小的线性范围内。然而，近年来非线性控制理论的发展使我们能够直接处理非线性系统。作为这类问题的典型例子，本文采用专门设计的具有强非线性特性的液压控制系统来研究液压机械手的定位问题。液压马达由四个旋转阀组成的桥路驱动，每个旋转阀由一个脉冲马达控制。基于系统反馈线性化和…的数学模型在设计伺服系统时，采用了更传统的极点配置方法。通过数值仿真和实验验证了该非线性液压系统与传统的线性液压控制系统的有效性。这为机械手的控制性能提供了灵活性。机械手的柔顺控制在人机界面环境中是很容易实现的，基于对阀内三维非定常流动结构的模拟，需要对控制阀进行优化，以适应非线性液压控制系统的目的。作为对这一问题的基本考虑，本文对滑阀的流动进行了非定常计算，研究了滑阀的动态特性，非线性引起的自激振动与系统的控制性能密切相关。对基本液压伺服系统进行了实验和数值仿真，并对液压控制系统中常见的几种粘滑振动进行了研究。较少

This research deals with fundamental research on positive utilization of the nonlinear characteristics of fluid control systems. Hydraulic control systems have advantages of high power and quick response but also have strong nonlinearity which prevents application of the modern linear control theory. Most hydraulic control systems have been designed through traditional PID control approach in which the nonlinearity of the system is ignored or the operation is restricted within a small linear range. However recent development of nonlinear control theory has enabled us to treat the nonlinear systems directly. As the typical example of such kind of problem, positioning of a hydraulic manipulator is investigated here using a specially designed hydraulic control system with strong nonlinear characteristics. A hydraulic motor is driven by a bridge circuit of four rotary valves each of which is controlled by a pulse motor. Based on a mathematical model of the system feedback linearization and … More conventional pole placement is applied to design the servo system. Numerical simulation and experiment were performed to confirm the validity of the present nonlinear hydraulic system in comparison with a traditional linear hydraulic control system.The present hydraulic manipulator has two degrees of freedom in its input. This provides the flexibility in control performance of the manipulator. Compliance control of the manipulator, which is essential in the man-machine interface environment, is easily realized.Optimization of the control valves applicable to the purpose of nonlinearity utilized hydraulic control systems is necessary based on the simulation of the 3-dimensional unsteady flow structure in the valves. As the fundamental consideration of this problem, unsteady calculation has been performed for the flow through the spool valve and its dynamic characteristics was investigated.Self-excited vibration due to nonlinearity is closely related to the control perfornance of the system. Experiment and numerical simulation has been performed for the fundamental hydraulic servo system and investigated on several types of the stick-slip vibrations which are generic to hydraulic control systems. Less