Vibration Suppression and Disturbance Rejection Control of Flexible Systems

柔性系统的振动抑制和干扰抑制是运动控制中的一个重要问题。它起源于轧钢系统，负荷通过轴耦合到驱动电机。由于新要求的速度响应非常接近这类系统的主共振频率，仅基于P&I控制的传统控制技术是不够有效的，为了克服这些问题，人们提出了各种控制策略，主要针对柔性系统的最简单模型--双惯性系统进行控制。本文首先回顾了从非常简单的方法、模型跟随控制、状态反馈控制到现代H_无穷控制等技术，然后重点讨论了基于干扰观测器的控制方法，如“谐振率控制”，并通过SIMULINK仿真验证了它的优良性能，最后提出了慢共振率控制。其优点如下：(1)用显式公式给出了扰动观测器的最优速度。(2)速度控制器可以独立于减振控制而设计，它的优良性能实际上体现在由两个电机和几个可调飞轮组成的特殊定制的实验装置上，飞轮由柔性轴连接。慢共振比控制在频率特性和时间响应波形上提供了足够稳定的无振响应。这是因为控制器中没有快速部件。此外，我们还可以使用为单惯量系统自主设计的速度控制器。这在大多数工业应用中是一个巨大的优势。

Vibration suppression and disturbance rejection in flexible system is an important issue in motion control. It originates in steel rolling mill system, where the load is coupled to the driving motor by a shaft. As the newly required speed response is very close to the primary resonant frequency of such systems, only the conventional techniques based on P&I control are not effective enough.To overcome the problems, various control strategies have been proposed mainly for controlling 2-inertia system, the simplest model of the flexible system. In this report, firstly, such techniques from very simple techniques, model following controls, state feedback controls and to modern H-infinity controls are reviewd.Next, the discussion was focused into the disturbance observer-based techniques, such as "resonance ratio control", and its excellent performance is shown by simulation using SIMULINK.Finally, the slow resonance ratio control is proposed. Its advantages are as follows :(1) The optimal speed of the disturbance observer is given by an explicit formula. It can by relatively slow.(2) The speed controller can be designed independently of the vibration suppression control.Its actually excellent performance is shown by usinf the specially ordered experimental setup consists of two motors and some adjustable flywheels connected by a flexible shaft. The slow resonance ratio control gives sufficiently stable vibration-less responses in frequency characteristics and time response waveforms. This is because there are no fast parts in the controller. Further, we can use the speed controller independently designed for 1-inertia system. This is a great advantage in most industrial applications.