计算机闭环控制系统在摩擦焊接中的应用

根据摩擦焊接过程质量控制需要 ,建立了摩擦焊接过程计算机电液比例闭环控制系统 ,实现了摩擦焊接过程中轴向压力的闭环控制、滑台进给速度的开环比例控制。生产现场数据统计分析表明 ,采用电液比例计算机闭环控制系统后 ,摩擦压力与顶锻压力的平均误差小于 2 % ,变异系数接近于 0 ,摩擦焊接参数的稳定性大大提高 ,有广泛的应用前景     

计算机辅助设计中的闭环设计方法及其实现

论述了产品的行为特性与其设计参数的关系,提出了通过构建行为特性函数利用设计结果调整设计参数的闭环设计方法。在计算机辅助设计中,应用闭环设计方法自动完成设计反复,使设计目标达到很高的设计精度,并可以进行可行性、灵敏度分析,实现优化设计。     

闭环模型测试法与计算机处理程序

模型测试是系统分析及改进机电设备的设计基础。闭环测试是一种既简单又安全的对象特性测试方法。在测试闭环衰减响应曲线的基础上，由测取若干响应曲线的特征数据，便可以求出对象模型的的阶次与结构参数，并由专用程序加以计算，仿真结果与实验数据经专用程序计算的结果完全一致，说明本方法有广泛的实用价值     

Improved closed-loop subspace identification with prior information

It has been proven that combining open-loop subspace identification with prior information can promote the accuracy of obtaining state-space models. In this study, prior information is exploited to improve the accuracy of closed-loop subspace identification. The proposed approach initially removes the correlation between future input and past innovation, a significant obstacle in closed-loop subspace identification method. Then, each row of the extended subspace matrix equation is considered an optimal multi-step ahead predictor and prior information is expressed in the form of equality constraints. The constrained least squares method is used to obtain improved results, so that the accuracy of the closed-loop subspace can be enhanced. Simulation examples are provided to demonstrate the effectiveness of the proposed algorithm.     

高精度磁场式时栅传感器激励信号对测量误差的影响分析及系统设计

为提高磁场式时栅传感器测量精度,本文从理论上推导分析了时栅传感器激励信号源幅值和相位不一致产生的谐波成分对时栅传感器测量精度的影响,提出了一种基于DDS原理并采用完整闭环调节的高性能时栅激励信号源设计方案。以FPGA为微处理器,通过编程分频系统时钟,设置频率、相位控制字对DDS输出的信号频率、相位进行调节,使用增益控制器配合相位累加器实现相位到幅值精确转换。搭建了信号调理电路和信号反馈电路,通过实时对比反馈控制,解决了系统电路阻抗不匹配及干扰导致的激励信号相位不正交性和幅值不一致性的问题。实验结果表明：本文所设计的激励信号源输出信号幅值相对误差只有0.4%,正交性相对误差只有0.05%,并且采用该激励信号源,磁场式时栅传感器测角原始误差从±103.4"降低到了±20.3",有效抑制由于激励信号源幅值不一致和相位不正交带来的谐波误差。经修正后对极内角位移测量误差只有±1.3",整周角位移测量精度达到±2",满足高精度位移测量要求。     

Closed-loop identification of wafer temperature dynamics in a rapid thermal process

Single wafer rapid thermal processing (RTP) can be used for various wafer fabrication steps such as annealing, oxidation and chemical vapor deposition. A key issue in RTP is accurate temperature control, i.e., the wafer temperatures should be rapidly increased while maintaining uniformity of the temperature profile. A closed-loop identification method that suppresses RTP drift effects and maintains a linear operating region during identification tests is proposed. A simple graphical identification method that can be implemented on a field controller for autotuning and a nonlinear least squares method have been investigated. Both methods are tested with RTP equipment based on a design developed by Texas Instruments.     

Control of pH processes based on the genetic algorithm

In this work, we propose a PID control strategy based on the genetic algorithm coupled with cubic spline interpolation method for the control of pH processes. The control scheme proposed in the present work consists of closed-loop identification based on the genetic algorithm and cubic spline method. First, we compute the parameters (K_C, Τ_I, Τ_D) of the PID controller using relay feedback and apply these parameters to control the pH Process. Then approximate linear models corresponding to each pH range are obtained by the closed-loop identification based on closed-loop operation data. The optimal parameters of the PID controller at each pH region are then computed by using the genetic algorithm. From numerical simulations and control experiments we could achieve better control performance compared to the conventional fixed gain PID control method. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

零电压开关准谐振半桥变换器的系统建模和研究

分析了零电压开关准谐振半桥ＤＣ／ＤＣ 变换器的工作原理和主电路谐振元件参数的计算方法, 推出了以ＭＣ３４０６７ 芯片为控制核心的系统闭环模型, 通过原理样机的实验验证, 表明计算方法和系统模型是合理正确的, 为相关变换器的研究打下了良好的基础。     

柔性机械臂振动控制研究

总结并分析了柔性机械臂动力学建模和振动控制的最新进展,建立了柔性机械臂振动控制实验系统,分别采用ＰＩＤ控制策略和线性二次型最优控制（ＬＱＲ）策略对柔性机械臂的振动控制进行了实验研究,并提出ＰＩＤ了控制与闭环反馈控制相结合的有效性。实验结果表明闭环应变反馈控制比单纯的的ＰＩＤ控制更为有效。     

不对称信息理论与非线性鲁棒控制算法

针对非线性船舶航向保持系统,通过设计其精确反馈线性化控制器,给出一种物理意义更明显的解释,即非线性精确反馈线性化控制器由非线性函数项和常规线性控制器组成．将简化的精确反馈线性化法与闭环增益成形算法相结合,设计其非线性鲁棒控制器,增加了信息的传递量,在提高系统鲁棒性能的基础上,使该算法成为实际工程上可用的算法．仿真结果表明,当信息传递充分时,航向保持效果良好．