改进型预测函数控制在感应电机功率优化中的应用

在对感应电机效率优化问题进行研究的基础上,考虑到传统方法在电机动态时无法同时兼顾响应性能和效率优化的缺陷,设计了一种新型分数阶PI(FOPI)预测函数控制策略.该控制策略将预测函数控制和分数阶PI两种算法相结合,构建具有分数阶比例、积分性质的多变量预测函数控制器,兼顾了感应电机动态效率与转速响应速度的优点.应用于电动机效率优化的最大转矩电流比控制方面,采用前馈补偿解耦设计的思路,将系统分解成两个具有可测扰动的子系统.仿真实验表明新型控制策略具有在线识别模型识别模型参数,跟踪效果好,抗干扰能力强,无超调,稳态误差小,取得了良好的控制效果.     

BLDCM新型滑模观测器的无位置传感器控制

针对传统滑模观测器(SMO)抖振和相位延迟问题,提出了一种新型滑模观测器来获取无刷直流电机(BLDCM)反电动势(back-EMF),无需额外增加低通滤波器即能得到光滑的反电动势估计值.由反电动势估计值能够直接计算出转子位置角和转速.根据转子位置角和滞环控制器的输出来选择适当的电压空间矢量,实现无位置传感器控制,并根据转速和反电动势估计值计算转矩.最后,将该滑模观测器用于无磁链环直接转矩控制(DTC)中.实验结果验证了方案的可行性.     

异步电机反馈线性化二阶滑模定子磁链观测器设计

为了提高异步电机定子磁链的观测精度,提出了基于反馈线性化的二阶滑模磁链观测方法,设计了定子磁链观测器,并应用到异步电机直接转矩控制中.为更准确的观测磁链,选取转子磁链为系统输出,运用微分几何理论将异步电机系统的输入/输出线性化,得到以转子磁链为输出的异步电机反馈线性化模型.在此基础上设计基于Super-twisting算法的二阶滑模转子磁链观测器,实现对转子磁链的准确估算,并对所设计的观测器进行稳定性分析.然后再利用转子磁链与定子磁链的关系,估算出定子磁链.将该观测器用于异步电机直接转矩控制中,达到了很好的控制效果.仿真与实验结果验证了该方法的可行性和有效性.     

扩展卡尔曼滤波结合前馈补偿永磁同步电机位置估计

转速和转子位置的精确估计对建立永磁同步电机(permanent magnet synchronous moter,PMSM)转速、电流双闭环矢量控制系统非常重要.本文主要研究扩展卡尔曼滤波算法(extended Kalman filter,EKF)估计转速、转子位置问题.与传统EKF估计转子位置方法不同的是,本文采用遗传算法(GA)优化EKF的协方差矩阵,并给出P,Q,R矩阵选取过程.另外将负载转矩观测器观测的负载转矩同速度调节器的输出一起作为电流调节器的控制变量.仿真及实验结果表明:文中提出的新方法有效缩短系统协方差参数选取时间,提高转速的辨识精度和抗负载扰动能力.     

液态肥扭力靶式流量计的研制及试验研究

为了实时检测液态肥变量施肥系统中排肥口的流量,研制了一种液态肥扭力靶式流量计.采用力-扭力管-应变电压的转换方式设计了流量计结构,建立了流量与应变电压的数学模型;采用FLUENT软件分析了不同靶片形状和不同直径比对扭力靶式流量计性能的影响;制作样机并对扭力靶式流量计的性能进行了校验实验.实验结果表明,该扭力靶式流量计测量结果稳定可靠,可测流量范围为0.2m3/h~3.9m3/h,误差小于2.0%FS.满足液态肥变量施肥系统中流量测量的要求.     

综合考虑CVT动力性和经济性的整车控制策略集成优化

传统的无级变速器（Continuously Variable Transmission,CVT）的策略优化集中在CVT换挡策略优化上,因此在提升燃油经济性的同时往往损害动力性。针对这一问题,在分析换挡策略和踏板扭矩策略对整车动力性和燃油经济性影响的基础上,提出集成优化换挡策略和踏板扭矩策略的方法;设计优化流程,得到不同车速、不同加速踏板开度下换挡策略和踏板扭矩策略的优化结果。搭建整车虚拟仿真模型,并进行仿真与试验对比分析,结果表明：集成优化可在保证动力性不衰减甚至提升的条件下,燃油效率提高约4%。     

基于感应电机状态方程的定子电阻辨识方法的研究

基于感应电机两相同步旋转坐标系状态方程,提出了一种新的定子电阻辨识方案。在分别利用励磁电流微分方程和转矩电流微分方程推算转速的基础上,利用二者的等量关系实现了定子电阻在线辨识。该方案的优点是,定子电阻估算仅需要电机终端可测的定子电压、电流,无须借助转子或定子磁链。仿真实验将其应用于无速度闭环矢量调速系统,实时更新转速估算模块中的定子电阻,论证了该方案对电机参数变化鲁棒性强及对改善转速估算精度的有效性。     

液力变矩器控制系统的特性与应用

液力控制技术是近年来发展起来的一个新的技术领域。文章阐述了液力变矩器控制系统目前实用的几种组成方法和特性 ,这有助于设计液力控制系统并拓展其应用领域。     

Isokinetic strength characteristics in wrist flexion and extension

A laboratory experiment was conducted to measure strength characteristics in dynamic (isokinetic) wrist flexion and extension. Twenty four college-age males exerted their maximum torque in both concentric flexion and extension at 60, 120, and 180°/s of angular velocity through a ±60° range of deviation from wrist neutral. Results show that velocity and motion direction significantly effected both peak torque as well as the postural displacement of peak torque. The value of peak torque decreased with an increase in velocity and the wrist angle at peak torque generally moved to a more deviated, flexed posture (from neutral) with increasing velocity as well. Peak torque for all velocity and motion-type conditions tested occurred in a flexed posture relative to neutral. It is anticipated that these results may be of use as biomechanically based considerations in the evaluation and design of upper extremity tasks involving wrist flexion/extension as well as to perhaps give insight into functional characteristics of the wrist. Finally, regression equations were developed to aid in the prediction of peak torque based upon task, individual and/or population parameters.

Relevance to industry

Results from this study should enhance the overall understanding of wrist functioning. Specifically, motion type, velocity of movement and wrist posture are important ergonomic design considerations. These results can also be used to modify existing biomechanical models that do not consider wrist variables.     

Control of three-link underactuated manipulators using a switching method of fuzzy energy regions

In general, manipulators used for industry and in academic laboratories have actuators to drive each joint. On the other hand, underactuated manipulators handled by our research have some passive or free joints without actuators and brakes. We recently developed a switching method of fuzzy energy regions to control such manipulators. In such a method, it is necessary to design parameters related to energy regions and the gains of some partly stable controllers based on the computed torque method. Here, the switching method is applied for a three-link underactuated manipulator. We optimize such design parameters related to fuzzy energy regions by a genetic algorithm. The effectiveness of the present method is illustrated with some simulations. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007