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A轴单元作为五轴数控机床的关键功能部件,其控制精度直接影响整体叶盘的加工精度和表面质量。针对摩擦、齿隙、参数摄动和测量噪声等非线性干扰对A轴伺服系统控制精度的影响,提出了基于线性二次型最优控制(LQC)和滑模控制(SMC)相结合的鲁棒控制算法(LQSMC)。该方法以系统状态空间表达式及LQC为基础,通过引入基于卡尔曼滤波器和控制输入的状态估计,对系统状态空间模型进行改进并定义新的滑模面方程,使得改进后的控制算法在性能上接近LQC并能有效抑制SMC的抖振。仿真分析和实验结果表明,LQSMC算法具有控制精度高、鲁棒性强和抑制干扰能力强等优点,其能有效提高A轴伺服系统的定位精度和跟踪精度,使整体叶盘型面加工精度和表面一致性得到保证,并显著降低了表面粗糙度。
A-axis unit as a key feature of five-axis CNC machine tools, the control accuracy of a direct impact on the overall leaf disc processing accuracy and surface quality. Aiming at the influence of nonlinear interference such as friction, backlash, parameter perturbation and measurement noise on the control accuracy of A-axis servo system, a new algorithm based on linear quadratic optimal control (LQC) and sliding mode control (SMC) Rod Control Algorithm (LQSMC). Based on the system state space expression and LQC, this method improves the system state space model by introducing the state estimation based on Kalman filter and control input, and defines a new sliding surface equation so that the improved control algorithm Performance close to LQC and can effectively suppress the chattering SMC. Simulation and experimental results show that the LQSMC algorithm has the advantages of high control precision, strong robustness and strong suppression of interference. It can effectively improve the positioning accuracy and tracking accuracy of A-axis servo system, Surface consistency is guaranteed and surface roughness is significantly reduced.