【作者】 张鑫；

【导师】 史铁林；

【作者基本信息】 华中科技大学 ， 机械工程， 2020， 硕士

【摘要】 复杂光学曲面突破了传统光学成像系统设计理论,极大地提高了光学系统性能。同时光学零件极高的精度要求给加工制造带来了挑战。单点金刚石车削因为可直接加工出达到光学应用要求的光学零件,得到了广泛地应用。其中慢刀伺服技术突破传统车削的限制,实现了非回转对称复杂曲面车削加工。本文以慢刀伺服加工中关键的直线进给轴精密运动控制为出发点,开展了如下工作:(1)分析了直线电机直驱运动的优势,通过系统辨识获得了直线电机模型实际参数后利用解析法设计了PID+前馈的复合控制器,并基于LQ最优控制理论,使用萤火虫全局搜索算法完成了PID最优控制参数的整定。(2)在分析了直线电机固有的推力波动问题后从控制的角度研究了两种不同的推力波动抑制方法,一是建立推力波动模型并在线辨识出模型参数通过前馈进行实时补偿。二是使用扰动观测器估计推力扰动并进行反馈补偿。最后综合二者的优势设计了推力波动复合抑制算法(3)研究了慢刀伺服车削轨迹规划方法,以生成直线进给轴的伺服指令输入。对比分析了不同刀触点离散方法的特点;研究了法向刀补和Z向刀补对进给轴运动的影响;讨论了自由曲线加工轨迹的PVT插补方法的优势;并结合三种典型复杂曲面进行了车削轨迹规划的仿真研究。(4)在基于Power PMAC的开放式运动控制平台上开展了相关实验。使用Simulink基于模型的设计功能,利用代码生成技术构建了自定义伺服中断程序,对比了不同算法对推力波动的抑制效果。最后编写了电机的运动程序,模拟了复杂曲面的慢刀伺服车削加工,并分析了转速、插补方法和曲面特征对加工精度的影响规律。更多还原

【Abstract】 The complex optical surface has broken through the traditional design theory of optical imaging system and greatly improved the performance of the optical system.However,the extremely high precision requirements of optical parts have brought challenges to manufacturing.Single point diamond turning has been widely used because it can directly process optical parts that meet the requirements of optical application.Among which,the slow tool servo technology breaks through the limitation of traditional turning and realizes the turning processing of non-rotary symmetric complex surface.In this paper,starting from the key precision motion control of the linear feed axis in slow tool servo machining,the following work is carried out:(1)The advantages of linear motor direct drive motion are analyzed,after the actual parameters of the linear motor model are obtained through system identification,the PID + feedforward composite controller is designed by the analytic method,and based on the LQ optimal control theory,the firefly global search algorithm is used to complete the tuning of PID optimal control parameters.(2)after analyzing the inherent force ripple problem of linear motor,two different force ripple suppression methods are studied from the perspective of control.The first is to establish a force ripple model and identify the model parameters online for real-time compensation through feedforward.Second,the disturbance observer is used to estimate the force disturbance and make feedback compensation.Finally,combining the advantages of the two methods,a compound force ripple suppression algorithm is designed.(3)The trajectory planning method of slow tool servo turning is studied to generate the servo command input of the linear feed axis.The characteristics of different tool contact discrete methods are compared and analyzed;the effects of normal tool compensation and Z direction tool compensation on feed axis motion are studied;the advantages of PVT interpolation method for free curve machining trajectories are discussed;and the simulation research of turning path planning is carried out with three typical complex surfaces.(4)Relevant experiments were carried out on the open motion control platform based on Power PMAC.Using Simulink’s model-based design function,a custom servo interrupt program was built using code generation technology,and the suppression effect of different algorithms on force ripple was compared.Finally,the motion program of the motor is written,to simulating slow tool servo turning for complex surface,and the influence of the speed,interpolation method and surface feature on machining accuracy is analyzed.更多还原