【作者】 赵杰；

【导师】 张海涛；

【作者基本信息】 华中科技大学 ， 控制理论与控制工程， 2016， 硕士

【摘要】 复杂曲面类零件在国防、运载、能源等行业应用广泛,其制造水平代表着国家制造业的核心竞争力。近年来五轴数控主动控制以及数字制造的发展给复杂曲面的加工带来了机遇和挑战,而加工时的振动或颤振严重影响了表面加工质量和效率。因此,基于磁悬浮轴承电主轴的智能主轴单元利用其具有主动改变主轴系统刚度以抑制加工振动的优点,展现了其在提高加工精度以及效率方面的巨大潜力。主动磁悬浮轴承是典型的机电一体化设备,其涵盖了机械、电气、电子、控制、计算机等学科的专业技术知识。磁悬浮轴承转子系统本身具有无接触、无磨损、无需润滑、高速、低功耗以及系统刚度可控等优点,因此磁悬浮轴承经常被用在涡轮机械、压缩机、加工主轴等领域的振动抑制方面。然而,虽有如此之多的优点,但磁悬浮轴承转子系统本身却是个开环不稳定的系统,故在其受到外界扰动的情况下,如何使其稳定且保持较高的刚度目前还是个具有挑战性的任务。本文首先介绍了一个柔性的磁悬浮轴承转子平台,并采用物理机理建模的方法得到了其多输入多输出且开环不稳定的状态空间模型。针对该模型,本文先介绍了包含参数不确定性的μ综合控制方法,其可以稳定该系统且具有一定的鲁棒性。接着,本文又提出了一个基于离散时域且同时受到输入与输出约束的模型预测控制(MPC)算法,仿真结果验证了该算法的可行性并探究了不同的输出约束对系统性能的影响。然后研究了受到输入约束的双模预测控制策略对该系统的作用效果,仿真结果说明该双模控制策略可以有效地扩大系统的初始状态吸引域,并可以较好的主动抑制系统受到的外界扰动。为了研究磁悬浮轴承对铣削加工过程振动的抑制效果,本文介绍了项目组定制的国内首台铣削电磁主轴(一种特殊的磁悬浮轴承转子系统),该主轴的最高转速可达40000转/分,额定功率为20kW且高速旋转时的回转精度不超过±10μm;该主轴将安装于五轴立铣机床上用以研究铣削加工过程中振动或者颤振的主动控制。针对上述的电磁主轴,探究了其悬浮以及高速旋转过程中转子位移以及轴承线圈电流的动态响应过程,并分析了其驱动器工作电压以及控制器的参数对系统性能的影响。接着,本文对电磁主轴的受力过程进行了建模分析,并采用PID控制方法分析了控制器参数与电磁主轴系统稳定性之间的关系。之后通过对磁悬浮控制系统的研究,本文完成了基于控制器dSPACE1103以及驱动器JSP-180-20等的电磁主轴悬浮控制硬件平台的开发,并借助Simulink控制模型完成了其软件控制系统的开发。最后本文完成了电磁主轴的悬浮实验并对实验结果进行了分析且提出了改进的措施。更多还原

【Abstract】 Complex surfaces are widely used in advanced manufacturing, space exploration, energy engineering, national defense, etc. In recent years, the development of five-axis NC active control and the digital manufacturing technologies bring new challenges on the manufacturing of complex surfaces. Hereby, active vibration even chatter control of machining process based on intelligent spindle especially active magnetic bearings(AMB) spindle for its capacity of increasing system stiffness shows much potential in improving machining efficiency as well as surface quality.Active magnetic bearings(AMB) are typical mechatronic products which involve a lot of subjects such as mechanical engineering, electrical engineering, electronics, control engineering and computer science. Due to the advantages of no friction, no fray, free of lubrication, high speed, low power consumption as well as controllable stiffness, AMB are often used to mitigate vibrations in turbines, compressors, machining spindles, etc. However, rotor-AMB systems are inherent open-loop unstable, and hence it is an urgent yet challenging task to stabilize rotor-AMB systems with external disturbances.A specified flexible rotor-AMB system is introduced in this paper. Firstly, a μ synthesis control method including parameter uncertainty is proposed to stabilize this unstable system along with its robustness analysis. Then, the stability of the rotor-AMB system subject to input and output constraints is investigated based on a discrete-time constrained model predictive control(MPC) algorithm to illustrate the effectiveness of the proposed controller in stabilizing the system with different output constraints. Next, a constrained dual-mode predictive control method is proposed hereby, which is afterwards proved to be capable of enlarging the region of attraction, and hence can effectively mitigate more intensive vibrations excited by external disturbances, which is desirable in real applications; finally,simulation experiments are conducted on the rotor-AMB system to show the effectiveness of the proposed dual-mode predictive controller.An AMB milling spindle platform is customized to investigate its performance of vibration suppression during machining process, which has a maximum rotating speed of40000 rpm, rotating accuracy less than ±10μm, rated power of 20 kW and torque more than5N·m. This AMB spindle is designed for a five-axis NC machine tool with intention of milling active vibration even chatter control.Based on the aforementioned AMB spindle, the rotor displacements and current response of AMB coils during different levitation and rotating experiments are investigated.Then the modeling and PID control process of rotor and magnetic force dynamics is proposed. Next, a new hardware platform based on controller dSPACE1103 along with AMB driver JSP-180-20 is developed through studying the control principles of rotor-AMB systems thoroughly. A Simulink model for the levitation control structure of the AMB spindle is fulfilled afterwards. Finally, levitation experiments are performed to investigate the performance of established levitation control system of the AMB spindle along with some analysis and rational improvement proposals.更多还原