Effect of thickness of friction material on contact state of ultrasonic motor

Performances of ultrasonic motor (USM) considerably depend on contact state between stator and rotor.Based on an electric contact method,the effects of thickness of single homogeneous friction material and gradient friction material on contact state between stator and rotor were studied.The relative contact length was employed to describe the contact characteristics of stator and rotor.With the decrease of thickness of friction material,the contact characteristic of stator and rotor were analyzed and compared when single homogeneous friction material and gradient friction material were used.The experimental results showed that the effect of gradient friction material on contact characteristic is smaller than that of single homogeneous friction material when the thickness of friction material decreases.The result can provide experimental guidance for design and choosing of friction material for USM.

An Algorithm for Idle-State Detection and Continuous Classifier Design in Motor-Imagery-Based BCI

Abstract-The development of asynchronous brain-computer interface （BCI） based on motor imagery （M1） poses the research in algorithms for detecting the nontask states （i.e., idle state） and the design of continuous classifiers that classify continuously incoming electroencephalogram （EEG） samples. An algorithm is proposed in this paper which integrates two two-class classifiers to detect idle state and utilizes a sliding window to achieve continuous outputs. The common spatial pattern （CSP） algorithm is used to extract features of EEG signals and the linear support vector machine （SVM） is utilized to serve as classifier. The algorithm is applied on dataset IVb of BCI competition Ⅲ, with a resulting mean square error of 0.66. The result indicates that the proposed algorithm is feasible in the first step of the development of asynchronous systems.

Study of Steady-state Performances for a Novel Line-start Single-phase Permanent Magnet Synchronous Motor With Three Parallel-connected Windings

对于三相感应电动机的单相运行,学者们已经提出了多种实用的接线方式,比如Smith接法、SEMIHEX接法。然而,对于三相异步起动永磁同步电动机的单相运行,很少有合适的接法提出。将并联式接法应用于三相异步起动永磁同步电动机的单相运行,提出了一种新型三绕组并联式异步起动单相永磁同步电动机。分析了三相异步起动永磁同步电动机同步运行时以及起动瞬间的正序、负序阻抗,基于对称分量法,对该接法电机的对称运行条件进行分析,得出了电容的确定方法,并利用遗传算法对电容值进行优化。提出了该新型电机稳态性能的计算方法;设计了一台高功率因数和一台低功率因数三相异步起动永磁同步电动机作为样机,并分别将其改接为三绕组高效单相永磁同步电动机,进行实验研究。实验结果表明,低功率因数的异步起动永磁同步电动机更适合改接成新型三绕组并联式单相永磁同步电动机。由低功率因数三相永磁同步电动机改接成的单相异步起动永磁同步电动机在额定负载下运行时,具有与同容量三相永磁同步电动机相近的效率和更高的功率因数。

基于自适应滑模控制器的PMSM调速策略研究

为了提高永磁同步电机的调速性能,滑模控制逐渐取代PI控制被引入控制系统中。但是传统滑模控制中趋近律的趋近速度慢与固有抖振问题制约着滑模控制的发展,为此提出一种改进的滑模趋近律。首先,为了解决传统等速趋近律中趋近速度和抖振难以平衡的问题,在所提趋近律中引入系统状态变量,并在滑模增益中引入指数项,使其在保证趋近速度的同时抑制滑模抖振。其次,由于开关函数在零点附近具有不连续的特性,会引起滑模抖振,为此采用sat函数代替常规开关函数,能够在保证响应速度的前提下抑制滑模抖振。然后,基于所提趋近律,设计永磁同步电机的滑模速度控制器。最后,仿真和实验结果表明,所提趋近律可以提高永磁同步电机调速系统的控制性能。

基于脑机接口的脑血管病后肢体运动功能康复研究进展

近年来,脑机接口在神经康复领域受到了广泛关注。常用的脑机接口实验范式包括运动想象及稳态视觉诱发电位等,已被广泛应用于运动障碍康复研究中。本文对脑机接口技术治疗脑血管病后运动障碍的机制以及基于脑电图的脑机接口在上肢和下肢运动障碍康复中的应用进展进行综述,结果表明,脑机接口技术可以帮助患者主动控制外接设备,并促进运动皮质神经通路重塑,实现运动功能的重建,在脑血管病康复中的应用潜力巨大。尽管脑机接口在研究层面取得了显著进展,但在实际场景中应用仍面临诸多挑战,尤其是在信号处理、跨被试研究和用户体验等方面。本文旨在为未来的研究提供一定的参考。

Observer-Based Nonlinear Control of A Torque Motor with Perturbation Estimation

This paper presents an observer-based nonlinear control method that was developed and implemented to provide accurate tracking control of a limited angle torque motor following a 50Hz reference waveform. The method is based on a robust nonlinear observer, which is used to estimate system states and perturbations and then employ input-output feedbazk linearization to compensate for the system nonlinearities and uncertainties. The estimation of system states and perturbations allows input-output linearization of the nonlinear system without an accurate mathematical model of nominal plant. The simulation results show that the observer-based nonlinear control method is superior in comparison with the conventional model-based state feedback linearizing controller.

A novel method to calculate the thrust of linear induction motor based on instantaneous current value

Because of the end effect, a linear induction motor （LIM） runs in an asymmetrical state even though the winding of each phase is symmetric. Based on the basic principle of the LIM, a new approach was proposed to calculate the thrust of the LIM using the instantaneous current value. A three-phase LIM model with 12 slots and a singlelayer winding was designed to validate this method. The experiments show that when the current is small, the calculated results basically agree with the experiments. The agreement becomes worse with the increase of the current because of the saturation of the primary iron core. The proposed formula is suitable when the iron core of the LIM primary is in an unsaturated state.

Analysis of torque-current characteristic of brushless DC motor driven by three-phase H-bridge

Presents the simulation and analysis of the steady state characteristic of a brushless DC motor studies the torque current characteristic of the motor as well and discusses the design of a current measure circuit for torque controlling.

LQ Speed Control of Pump Controlled Motor System

A linear quadric (LQ) optimal speed control algorithm is proposed for the speed control of a pump controlled motor hydraulic system. The control theme consists of optimal state feedback and disturbing compensation based on observation. The optimal state feedback bases on LQ cost function. The disturbing compensation is realized through reconstructing the state of load torque. A series of simulation are performed, and the results show that the control performance is satisfactory and can be maintained under changes of load torque.

Analysis and Design of Derivative Free Filters against Derivative Based Filter on the Simulated Model of a Three Phase Induction Motor

Recursive state estimation methods have aroused substantial attraction among many researchers and in particular, the drives research fraternity has shown increased interest in recent years. State estimators that surrogate direct measurements play an integral part in the operation of modern a.c. drives. Their robustness and accuracy are very much decisive for the performance of the drive. In this paper, a comparative analysis of the three nonlinear filtering schemes to estimate the states of a three phase induction motor on the simulated model is presented. The efficacy of Ensemble Kalman Filter (EnKF) against the traditional Jacobian based Filter or Extended Kalman Filter (EKF) and almost forbidden, hitherto least-attempted Unscented Kalman Filter (UKF) is very much exemplified. Theoretical aspects and comparative simulation results are investigated comprehensively with respect to three different scenarios viz., step changes in load torque, speed reversal, and low speed operation. Also, “Monte Carlo Simulation” runs have been exploited very extensively to show the superior practical usefulness of EnKF, by which the minimum mean square error (MMSE), which is often used as the performance index, ostensibly gets mitigated very radically by the proposed approach. The results throw light on alleviating the intrinsic intricacies encountered in EKF in parlance with the observer theory.

基于状态估计的轮毂电机驱动控制策略研究

为克服轮毂电机响应慢,控制精度和抗干扰性差的难题,本文在滑模控制(Sliding mode control,SMC)的基础上,开发基于转速和角度在线状态估计的超螺旋滑模(Super-twisting sliding mode control,STSMC)轮毂电机转速转矩联合控制策略。采用单移线工况,轮毂电机汽车匀速换变道时分别对各轮毂电机进行转速控制,满足阿克曼转向要求,变道后采用正弦过渡方法对各轮毂电机进行转矩控制,电机快速平滑输出期望转矩,车辆直线加速。为防止转速和角度传感器误差或者损坏,轮毂电机控制中采用最大相关熵平方根广义高阶容积卡尔曼算法(Maximum correlation entropy square root generalized high-order cubature Kalman filter,MCSRGHCKF)对转速和转子角度进行无传感器估计,实验测试得到转子角度估计误差为-0.05 rad,转速误差为0.3 r/min,满足电机控制要求。从电机启动到匀速运行阶段采用STSMC算法控制,转速超调量为6.33%,最大输出转矩为0.35 N·m,响应时间为0.22 s,稳态转速脉动为±0.5 r/min,转矩脉动为±0.01 N·m,相比PID和SMC算法,控制效果更佳。在转速切换转矩控制,转矩可按照正弦函数平滑过渡,最大超调仅为2.86%,电机运行平稳。

PMSM speed control using adaptive sliding mode control based on an extended state observer

In this study,a composite strategy based on sliding-mode control( SMC) is employed in a permanent-magnet synchronous motor vector control system to improve the system robustness performance against parameter variations and load disturbances. To handle the intrinsic chattering of SMC,an adaptive law and an extended state observer( ESO) are utilized in the speed SMC controller design. The adaptive law is used to estimate the internal parameter variations and compensate for the disturbances caused by model uncertainty. In addition,the ESO is introduced to estimate the load disturbance in real time. The estimated value is used as a feed-forward compensator for the speed adaptive sliding-mode controller to further increase the system's ability to resist disturbances. The proposed composite method,which combines adaptive SMC( ASMC) and ESO,is compared with PI control and ASMC. Both the simulation and experimental results demonstrate that the proposed method alleviates the chattering of SMC systems and improves the dynamic response and robustness of the speed control system against disturbances.

基于扩张状态观测器和抗饱和输入的伺服电机等效反步滑模控制

为了提高伺服电机系统的动态响应速度、抗干扰能力,解决输入饱和的问题,课题组基于扩张状态观测器(extended state observer,ESO)和抗饱和输入(anti-saturation input,ASI)辅助系统设计了伺服电机的运动控制方案。首先,建立了伺服电机的数学模型,将系统阻尼和系统不确定性归为扰动,将扰动设为系统的扩张状态;然后在等效反步滑模控制(backstepping sliding mode control,BSMC)的基础上,引入了ASI辅助系统和ESO,解决输入饱和问题,并抑制内、外干扰;采用双曲正切饱和函数替换符号函数以减小滑模控制的抖振;通过李雅普诺夫稳定性方法检验所提出控制器的稳定性。最后,将基于ESO和ASI的等效反步滑模控制与比例积分微分(proportional integral differential,PID)控制、滑模控制(sliding mode control,SMC)进行仿真对比。结果表明:相较于传统PID和SMC控制器,课题组所设计的控制器可以实现伺服电机的无超调快速响应,解决了输入饱和问题,并具有较好的抗干扰能力和减小输入冲击的作用。

基于改进扩张状态观测器的PMLSM控制策略

针对永磁同步直线电机(PMLSM)在运行过程中对负载变化与外部扰动较为敏感问题,提出一种改进型扩张状态观测器(ESO)的控制方法,该方法对传统ESO的扩张状态项进行优化,加快了扩张状态项的响应速度,并将其补偿至速度外环控制器的输出,从而加快q轴电流给定响应速度,可以进一步提升系统的动态性能与抗扰动能力。同时利用Lyapunov判据证明改进观测器的稳定性,最后通过实验验证证明改进型ESO相比于传统ESO,系统可以更快的速度响应外部扰动,在系统受到外部扰动时引起的速度跌落更小,进一步提升系统的动态性能与抗扰动能力。

孤独症儿童的“体育与健康课程”教学内容设计与教学效果检验

目的:设计符合孤独症(孤独症谱系障碍,Autism Spectrum Disorders, ASD)儿童身心发展的“体育与健康课程”教学内容,通过10周教学实验检验其对ASD儿童动作协调能力和运动皮质静息功能连接的影响。方法:根据孤独症儿童的身心发展特点,设计了一套以执行功能提升和篮球技术提高为目的的教学内容。共招募11名ASD儿童,持续进行为期10周的教学实验。实验前、后分别应用动作协调能力测量量表(M-ABC2)量表测量受试者动作协调能力,运用功能近红外光谱(fNIRS)监测运动皮质安静状态下的血氧信号,并用“FC-NIRS”软件计算脑区的静息功能连接(RSFC)强度。结果:(1)在实验前后,ASD儿童M-ABC2总分及一级指标(手部精细动作、手眼协调动作以及动态静态平衡能力)均未见有显著性变化(P>0.05);(2)在HbO水平上,实验前后运动皮质RSFC具有临界显著变化(t=2.30,P=0.06),且具有较大的效应量(d=0.87)。结论:持续10周的执行功能和篮球运动对ASD儿童动作协调能力的影响不显著,但对运动皮质静息功能连接具有一定的作用。

基于ESO分数阶滑模调节的PMSM模型预测转矩控制

为了提高永磁同步电机调速系统的性能,提出一种基于扩张状态观测器的分数阶滑模预测转矩控制策略。采用扩张状态观测器对电机的综合扰动项、定子电流和反电动势进行实时观测,可快速准确得到它们的估计值并进行补偿;利用估计值构建分数阶滑模控制器来削弱系统抖振并提高鲁棒性;利用转矩和磁链无差拍预测控制,减少了遍历次数并降低了计算复杂度。通过仿真和半实物平台进行了验证,所得结果表明,所提出的方法能有效提升系统的鲁棒性,使电机具有良好的动态和静态性能。

基于比例谐振内模扩张状态观测器的PMLSM推力波动抑制策略

定位力是永磁同步直线电机(PMLSM)产生推力波动的主要原因,导致振动和噪声,恶化驱动系统运行性能。针对这一问题,该文提出一种基于比例谐振内模扩张状态观测器(PR-IMESO)的PMLSM推力波动抑制策略以提高系统控制精度和运行性能。首先,对PMLSM推力波动进行建模与分析,针对推力波动中占比较大的定位力分量,根据内模原理研究考虑定位力模型的内模扩张状态观测器(IMESO),并在观测器中引入谐振项以加强对二次脉动定位力的抑制。所提出抑制策略对PMLSM定位力具有良好的观测及补偿能力,还可对其余未建模的复杂动子推力波动进行抑制,具有较好的推力波动整体抑制效果。最后,在一台750 W的PMLSM实验平台上验证所提出抑制策略的有效性。

An Optimal Control Theory Based Analysis of Brushless DC Motor Drive

The application of BLDC motor drives in industries is becoming more popular nowadays. An error will occur in the drive that is originated by some disturbances which are the major problems to reduce the stability of the system. To obtain the minimum performance index, the optimal control signal is formulated, which is the main objective of this paper. Based on quadratic performance index, the optimal control system of BLDC motor drive is a design which spotlights in this paper. The complexity of the mathematical expressions has been reduced by using state space approach to the BLDC system. The burden to the control engineers has reduced based on tedious computation by using thus optimal design. To provide the desired operating performance, this optimal design helps to realize the BLDC system with practical components.

基于单片机的直流电机变频调速方法与仿真

针对电机谐波损耗及逆变器输出谐波信号影响直流电机变频调速的稳定性,导致调速性能不佳等,提出一种基于单片机的直流电机变频调速方法。建立直流电机变频调速状态空间模型,通过上述模型获取变频调速系统的运行状态;采用电流、速度双闭环PI控制器实现直流电机的变频调速初步控制,使直流电机变频调速系统可同时满足静态性能与动态性能;将直流侧电压输入至SVPWM脉宽调制系统,进一步降低电机谐波损耗和脉动转矩,实现变频调速的精确控制。仿真结果表明,所提方法的直流电机变频调速稳定性更佳、精度更高,整体效果更佳。

PMSM无模型滑模转速无差拍电流预测控制

针对传统永磁电机调速系统易受到参数摄动影响而导致控制精度下降的问题,提出一种基于扩张状态观测器(ESO)的永磁同步电机(PMSM)无模型滑模转速无差拍电流预测控制策略。首先用参数摄动下的PMSM调速系统数学模型归纳出系统对应的超局部模型,然后结合无差拍预测控制思想设计了电流环控制器,采用两步预测算法解决了传统无差拍算法存在的延时问题,并且提出校正算法进一步抑制实际的预测误差;利用变速率指数滑模趋近率设计了新型无模型滑模速度控制器,减弱抖振的同时提高了系统响应速度;并设计ESO对参数失配和扰动进行估计和补偿。最后,通过仿真与半实物实验验证了所提控制策略的有效性。