基于剪切式阻尼可控与末端微振动抑制的自适应鲁棒高速超精密运动控制方法研究

A composite actuator composed of contollable shear-mode damper and linear motor is proposed, which not only has the advantages of fast response, high positioning accuracy, no transmission mechanism and less friction loss, but also can suppress micro-vibrations generated by both the excitation of base motion and the self-excitation of flexible manipulator to realize ulta-precision motion control. Therefore, the proposed actuator will greatly contribute to the upgrading of high-end equipments in many engineering fields such as robotics, precision manufacturing and aerospace etc.. However, the dynamic rigid-flexible coupling stiffness is formulated as partial differentiable equations with infinite orders, micro-vibrations are rather hard to measure and observe, and the magnetorheological fluid (MRF) damper has the charateristics of strong coupling and nonlinear behaviors in mechanic-electric-magnetic-fluid fields and magnetic saturation phemomenon as well. Morover, there are no sophisticated methods for coordinating multi-loop outputs between linear motor, driving unit damper and supporting unit damper. These factors bring great challenges in realizing high speed and ultra-precision motion control of such a composite actuator. In this project, the high performace of the damper will be achieved through the optimization design of both structural parameters and magnetic circuits, and the optimal coordinating control law of controllable damper will be investigated for stablizing the dynamics of flexible structure states through estabilishing the flexibele structure observer with multi-order vibration modes and mode coordinates, and the large amplitude vibration of flexible manipulator will be compensated by a constrained optimization adaptive robust controller, while the micro-vibration generated by the self-excitation of flexible manipulator and the base excitiation will be greatly suppressed by the controller of dampers. As such the nanoscale ultra-precision motion with high speed will be achieved under variable loads, and the system has strong capability of resistanting to various disturbances through combining motion with vibration.

剪切式可控阻尼与直线电机集成的复合驱动器既有响应快、精度高、无传动机构、无摩擦损耗的优点，又能抑制基端激励与柔性臂自激产生的微振动，实现超精密运动控制，将有助于机器人、精密制造与航空航天等领域高端装备的转型升级。但是，动态耦合刚度具有无限阶偏微分特性，微振动难以测量与状态观测，磁流变阻尼器带有机-电-磁-液非线性耦合特性与磁芯饱和现象，直线电机、驱动阻尼与支撑阻尼控制器多回路输出的协调控制尚未有成熟方案，给复合驱动器的高速超精密控制带来挑战。本项目通过阻尼器结构参数与磁路的优化设计获得阻尼器的高性能输出；通过含多阶模态振型与模态坐标的柔性结构状态观测器，建立可控阻尼的最优调控规律并使柔性结构的动态方程镇定；通过受限优化的自适应鲁棒运动控制器补偿柔性臂的大幅振动，通过阻尼控制器抑制基端激励与柔性臂自激产生的微振动；将运动与振动结合，实现高速与变负载工况下的纳米级超精密控制，且具有强抗干扰性。

本项目提出一种新原理的剪切式可控阻尼与直线电机集成的复合驱动器用于驱动柔性结构系统，以探索柔性结构系统刚柔耦合复杂动态特性，末端微振动的动态建模与有效抑制，直线电机、驱动阻尼与支撑阻尼控制器多回路输出的协调控制，实现柔性结构系统的精密运动控制和末端振动抑制的驱动-控制一体化设计为研究目标。项目的主要研究成果有：(1)提出了剪切式磁流变阻尼单元的原理方案，并提出了性能导向的磁流变阻尼单元的结构参数受限优化设计方法以获得其在有限空间内满足应用需求的最优结构。(2)研制了用于磁流变阻尼器控制的比例放大器原型样机，设计了用于高速开关阀控制的基于硬件数字电路和基于软件单片机的两种PWM驱动器电路。建立了比例放大器和PWM生成器的输入输出模型关系，试验测试了其性能关系。(3)构建了伺服电机驱动旋转柔性臂的试验平台系统，分析了小变形假设下的刚柔耦合系统动态模型和振动模态特性，提出了基于时域和频域模型的系统辨识方法来减小建模误差，并提出了基于输出重定义和快慢时间尺度子系统分解的自适应鲁棒末端轨迹控制方法，实现柔性结构系统的高精度运动性能和较好的末端振动抑制性能。(4)构建了剪切式可控阻尼与直线电机的复合驱动器及其驱动柔性臂的试验平台系统，分析了支撑阻尼和驱动阻尼对改善柔性结构系统定位稳定性和末端振动抑制的影响，提出了可变支撑阻尼与基端驱动量的协调控制以提高运动性能的方法，其通过设计与振动状态和参考轨迹相关的阻尼控制量来快速进行抑振，并通过基于系统动态模型的尺度分解与输出重定义的自适应鲁棒控制来改善柔性臂系统的末端轨迹跟踪效果。本课题开展的可变阻尼与基端联合驱动的柔性臂系统的研究，构建了针对柔性结构系统在运动学和动力学约束下的系统运动控制-振动抑制的一体化设计方法，为解决目前工业界面临的柔性结构系统运动跟踪的高精度高效率以及振动的快速抑制保证系统稳定性这一难题提供了理论和技术支持，具有重要的学术及现实意义。