磁流变阻尼器无模型前馈/反馈复合控制

为了实现磁流变(MR)阻尼器高可靠性和高精度的阻尼力跟踪控制,克服基于逆向动力学模型的前馈控制易受模型误差和外界干扰影响的问题,提出结构简单、实现容易的无模型前馈/反馈复合控制(MFFFFBC)方法.利用磁流变液减振器阻尼力连续可调的特点,将磁流变阻尼器控制器前一时刻的控制量进行采样保持作为前馈控制器,以避免建立复杂的磁流变阻尼器逆向动力学模型.利用期望阻尼力与实际阻尼力之间的跟踪误差信号构建反馈控制器对前馈控制量进行实时修正,利用饱和函数对控制电压进行限幅,以避免控制电压高频振荡.试验结果表明,在MFFFFBC控制下输出电压连续光滑变化,与经典的基于Heaviside阶跃函数的控制相比,采用本研究所提出的控制策略,黏性阻尼力和摩擦阻尼力的跟踪误差分别减小了21.98%和26.64%.

气动力/直接力复合控制系统零极点配置设计

为提高气动力/直接力复合控制系统的性能,针对直接力喷流操纵不确定性对复合控制系统的动态品质的影响,采用零极点配置设计复合控制系统自动驾驶仪的方法。给出了气动力反馈/直接力前馈的复合控制自动驾驶结构,分析了直接力前馈控制对复合控制系统零点的影响。分别采用极点配置和零点配置方法设计了气动力反馈控制回路和直接力前馈回路,保证了复合控制系统具有理想的动态品质和对喷流不确定性的鲁棒性。通过复合控制系统六自由度仿真验证了方法的有效性。研究对于气动力/直接力复合控制系统设计具有较强的工程应用价值。

中药质量源于设计应用:工艺控制策略

在药品质量源于设计(Quality by Design,QbD)框架下,工艺控制策略是用于确保产品质量和工艺性能符合预期目标的一套计划性控制方法和步骤的组合。工艺控制策略的先进程度取决于对药品和制药工艺的理解和相关知识水平的积累。目前,国内制药工艺控制正经历从质量源于检验(QbT)模式向QbD模式的转变。本文总结并比较了分别由美国FDA的Lawrance Yu和国际制药工程协会PQLI工作组提出的工艺控制策略等级模型。介绍了药物产品质量实时放行测试、工艺设计空间、工艺前馈控制和反馈控制、工艺闭环控制、工艺智能控制等先进工艺控制方法和策略,及其在中药和药品生产中的应用。

Simulation Study on Active Roll Control of Vehicles

The effects of active control on the vehicle roll were studied. Based on the theory that distributing the greater roll stiffness to the rear axle can improve tracking trajectory capacity and increase maneuver stability, an eight degrees of freedom vehicle model was established and feedforward feedback control strategy was devised to control distribution of lateral load transfer on the front axle and the rear one. Simulation results showed that the proposed control strategy can improve comfort, maneuver stability and safety effectively.

Hybrid control based on inverse Prandtl-Ishlinskii model for magnetic shape memory alloy actuator

The hysteresis characteristic is the major deficiency in the positioning control of magnetic shape memory alloy actuator. A Prandtl-Ishlinskii model was developed to characterize the hysteresis of magnetic shape memory alloy actuator. Based on the proposed Prandtl-Ishlinskii model, the inverse Prandtl-Ishlinskii model was established as a feedforward controller to compensate the hysteresis of the magnetic shape memory alloy actuator. For further improving of the positioning precision of the magnetic shape memory alloy actuator, a hybrid control method with hysteresis nonlinear model in feedforward loop was proposed. The control method is separated into two parts: a feedforward loop with inverse Prandtl-Ishlinskii model and a feedback loop with neural network controller. To validate the validity of the proposed control method, a series of simulations and experiments were researched. The simulation and experimental results demonstrate that the maximum error rate of open loop controller based on inverse PI model is 1.72%, the maximum error rate of the hybrid controller based on inverse PI model is 1.37%.

The Disturbance Rejection in Singular Systems

Using linear state feedback and linear feedforward control of the disturbances, the problem of achieving the distrubance rejection in a linear time invariant singular system is treated and a constructive solvability condition is presented.

Adaptive Stabilization for a Class of Feedforward Systems with Zero-Dynamics

This paper investigates adaptive state feedback stabilization for a class of feedforward nonlinear systems with zero-dynamics, unknown linear growth rate and control coefficient. For design convenience, the state transformation is first introduced and the new system is obtained. Then, the estimation law is constructed for the unknown control coefficient, and the state feedback controller is proposed with a gain updated on-line. By appropriate choice of the estimation law for the control coefficient and the dynamic gain, the states of the closed-loop system are globally bounded, and the state of the original system converges to zero. Finally, a simulation example is given to illustrate the correctness of the theoretical results.