永磁同步直线电动机冷却系统结构设计

永磁同步直线电动机运行过程中产生大量的热量,严重影响电动机的正常运行。现提出一种结构简单、性能可靠的电动机水冷冷却系统。在设计中采用Ansys有限元分析软件对永磁同步直线电动机进行了三维温度场计算,清晰展示出电动机内部各部分的温度以及整个电动机的温度曲线。针对该温度场,设计相应的水冷冷却结构,并再次模拟仿真出带冷却系统的电动机温度场分布。最后通过温升实验,验证了计算结果,并证明上述水冷冷却结构的工程可行性,解决了长期困扰中国大功率直线电动机发热严重的问题。     

Feedforward element design using learning controller for precision control of linear synchronous motor with nonlinear characteristics

This study presents a time-invariant feedforward (FF) element design for the high-speed and high-precision tracking control of an ultrahigh-acceleration, high-velocity linear synchronous motor (LSM). The linear motor can generate an acceleration greater than 70 G (= 686 m/s²) and move at a velocity above 10 m/s. To take advantage of this performance and realize high response, the design and usage of suitable FF elements is crucial. However, as the LSM includes highly nonlinear characteristics, it is difficult to provide an exact dynamic model for FF design. To overcome this problem, a control system with a learning controller (LC) as the FF element has been designed previously, demonstrating high-precision and high response motion. However, the motion performance can be achieved only with sufficient pre-learned motions. The integrator and the disturbance observer that were effective in suppressing disturbances were removed from the control system. In addition, the control system has some FF time-invariant elements along with the LC. This study proposes a design method for easy design of all FF elements using an LC. The designed FF elements are time invariant and are used with an integrator and a disturbance observer, without pre-learning. Using the proposed method, two sets of time-invariant FF elements are designed. The performances of two control systems, which include a set of time-invariant FF elements for each, and a simple disturbance observer are experimentally examined and compared with two previously designed control systems. Experimental results demonstrate that the performance of one of the control systems with a set of time-invariant FF elements designed in this study and a disturbance observer is good and almost comparable with that of the previously designed control system with high-precision and high response motion.     

Tracking control of concentration profiles in a fed-batch bioreactor using a linear algebra methodology

Based on a linear algebra approach, this paper aims at developing a novel control law able to track reference profiles that were previously-determined in the literature. A main advantage of the proposed strategy is that the control actions are obtained by solving a system of linear equations. The optimal controller parameters are selected through Monte Carlo Randomized Algorithm in order to minimize a proposed cost index. The controller performance is evaluated through several tests, and compared with other controller reported in the literature. Finally, a Monte Carlo Randomized Algorithm is conducted to assess the performance of the proposed controller.     

Research on the control systems of a precision linear motor drive device

The model of a precision linear motor drive device (PLMDD) and its control requirements are analyzed. In order to enhance the tracking and anti-disturbance performance of the system, its third-order model is established, and disturbance-observer based input revising feedforward error compensation robust control algorithm, combined with integral-separated proportional integral derivative (PID) control algorithm is proposed. This includes feedback control algorithm and feedforward control algorithm. The feedback controller improves system tracking performance and suppresses load and mechanical disturbance while the feedforward controller compensates phase hysteresis introduced by feedback control. Theoretical analyses, simulations and experiments show that this control method increases the tracking precision of PLMDD from ±5 μm to ±2 μm and dramatically improves its anti-disturbance ability.     

直线电机伺服系统的设计与应用研究

简单介绍了直线电机的分类和优点，设计了一种直线电机伺服系统的结构，说明了驱动器的使用方法及其基本工作原理，对应不同的控制参数采集速度控制和位置控制的伺服曲线，建立了直线电机伺服系统的控制模型，比较了模型运算结果和实际测试采样结果，分析了控制算法及参数对伺服系统性能的影响，描述了最终伺服系统所达到的性能指标。     

Tribological behavior of reciprocating friction drive system under lubricated contact

The dynamic friction and wear behaviors are investigated in reciprocating friction drive system using a 0.45% carbon steel pair. The effects of various operating parameters on the traction force, stick and slip time, and friction modes are examined under the lubricated contacts. Moreover, the critical operating conditions in classifying three friction modes are also established. Results show that the fluid friction induced by the shearing of lubricant dominates the variation of traction force and produces the positive slope γ at the first period of slip in the traction force–relative sliding velocity curve. The γ value decreases at higher driver speed during stick-slip motion due to the thicker fluid film and shear thinning effect. The γ value increases due to the asperity interactions as the friction region is transferred from stick-slip to sticking with normal load from 196 to 980 N. Furthermore, it is also found that the static friction force is independent of stick time for the tangential loading rate ranged from 1.12 to 16.8 s⁻¹. The transition region produces the severest wear under the different driver speeds, but the wear is insensitive to the friction regions and the severe wear only occurs at higher normal load due to the action of Hertzian contact.     

Control of a dual stage magnetostrictive actuator and linear motor feed drive system

A dual stage feed drive system is well suited to satisfying current demands of high performance machining with tight position control under high feed rates in the presence of disturbances. It does this by integrating an actuator with high position resolution and fast response together with a conventional linear drive. A magnetostrictive actuator (MA) with a bandwidth in the kHz range capable of several kN of force output is an ideal candidate for use as the fine positioning element in such a dual stage system. However, MAs display significant hysteresis in their performance. This makes the effective implementation of real-time fast servo control challenging. In this paper, a dynamic Preisach model is utilized to reduce the undesired nonlinearity. A sliding mode controller (SMC) is designed to deal with uncertainties such as the Preisach modeling error as well as external disturbances so as to ensure a robust stable system. Experimental results show the servo performance improvement during a feed step test for single axis control and a single axis component of a sharp path interpolation test.     

直线电动压缩机的活塞优化设计分析

为了满足直线电动压缩机的活塞高速化和轻量化要求,介绍了在PRO／MECHANIC环境下,对其活塞的应力和变形进行有限元分析,并对活塞进行优化设计,使其在满足强度和高速运转的情况下,质量达到最小,降低了惯性力,得到主要参数的最佳值,满足设计要求。     

Modeling and control compensation of nonlinear friction using adaptive fuzzy systems

System performance in terms of control accuracy and stability is usually negatively affected by friction occurrences in mechanical systems. Thus, it is important to model the friction properly so that it can be used in controller design. This paper employs adaptive fuzzy systems to approximate unknown nonlinear friction functions, and applies the estimation of friction in proportional-derivative (PD) control law to enhance the control performance. On the basis of Lyapunov stability theory, a bound of tracking errors of the closed-loop control system is derived. Techniques proposed in this paper have been applied to a typical motion control system for simulation studies. The results obtained demonstrate that our proposed method in this paper has good potential in controlling many mechanical systems with unknown nonlinear friction.     

基于虚拟仪器的双轴柔性辊弯成型机控制系统设计

在介绍变截面辊弯成型原理的基础上,描述了双轴变截面辊弯成型机结构,阐述了基于虚拟仪器思想的成型机控制系统构成,给出了实现变截面成型的软件设计思想,最后通过成型实验分析了成型轨迹控制精度.     

拖拉机制动系总成虚拟装配设计的研究

基于Pro/E系统环境,通过对拖拉机制动系总成进行虚拟装配设计,介绍了在Pro/E中建立常用零件及标准件的方法.完成了制动系统所有零部件的装配设计,同时进行了运动机构.建立了制动系统装配体的爆炸视图,直观地表达了装配的顺序.进行了运动仿真,分析了运动的过程及零件之间的相互联系,进行了干涉分析.制作了模拟动画,直观地展示了制动系统的工作过程.     

应用潜变量回归在线补偿双直接进给轴热误差

为了提高直线电机驱动的双直接进给轴的运动精度,对该类进给轴的热误差进行了建模并研究了误差补偿方法。分析了双直接进给轴进给过程中热误差产生的原因及其补偿的复杂性,给出一种基于潜变量回归的双直接进给轴热误差在线补偿方法。该方法应用激光干涉仪测量进给轴的热变形量,使用热电偶和红外测温仪测量进给轴关键点的温度变化;通过时间匹配变形和温度数据得到统计样本并建立基于潜变量回归的热误差识别模型。以模型的在线计算确定误差补偿量,给出了与数控系统兼容的补偿控制输出策略及补偿系统构建方案。在自构建的龙门双直线电机驱动进给轴平台上进行了在线补偿实验。结果表明:应用潜变量回归方法对双直接进给轴进行热误差补偿可使双直接进给轴的热误差减小75%。     

Trajectory tracking for two-degree of freedom helicopter system using a controller-disturbance observer integrated design

Trajectory tracking control for helicopters, which are widely used in severe situations such as military and rescue missions, is a challenging field of research. In helicopter system, the stability problem and predefined trajectories tracking are main challenges, especially in the presence of external disturbances and dynamic model uncertainties. Hence, a robust control design is needed for tracking the desired references. There has been a lot of motivation for solving these problems with simpler methods and also reducing the couplings in the helicopter system to achieve better performance, as the presented paper attempts to fill these gaps. This paper focuses on designing control laws for two-degree of freedom helicopter system while assuring the closed-loop stability. A nonlinear disturbance observer-based control (NDOBC) is designed for attenuating the effects of exogenous disturbances. Trajectory tracking controller and nonlinear disturbance observer are formulated in the form of two linear matrix inequality (LMI) problems. The closed-loop system stability, including controller and observer, is investigated by Lyapunov theorem. The effectiveness of the proposed design for tracking the trajectories (vertical flight and pitch angle rotor blade) and disturbance estimation is verified by simulation results.     

Development and precise positioning control of a thin and compact linear switched reluctance motor

This paper describes the development and precise positioning control of a thin and compact linear switched reluctance motor (LSRM). The LSRM that has been developed has a mover that is easy to fabricate and can be disposable. The mover can be easily separated from the stator, allowing it to be changed frequently or discarded in a hazardous application. The prototyped LSRM mover is only 0.128 mm thick with the stator measuring 2.0 mm at its thickest point. These features are highly desirable for space savings while being cost-effective. However, the LSRM has a strong nonlinear driving characteristic that presents a challenge with respect to precision control. In order to overcome this problem and achieve precision positioning, a linearizer unit was designed and integrated into the controller to compensate for the nonlinear relationships among the effective thrust force, mover position, and excitation current. The usefulness of the designed controller was examined experimentally. The experimental positioning results show that the steady-state errors were all less than 1 μm in the working range of the LSRM. In addition, the redesign for the improvement of thrust characteristic and easy fabrication of the LSRM is explained.     

基于虚拟主机技术的微机配料系统设计及实现

详细论述了利用虚拟技术构成分散控制的微机配料系统的原理、总体构成及实现方法，并给出应用实例。这种技术在不增加硬件成本的前提下，使系统可靠性大大提高，具有广阔的应用前景。     

System construction of a four-side primary permanent-magnet linear motor drive mechanical press

Frontiers of Mechanical Engineering - A primary permanent-magnet linear motor (PPMLM) has a robust secondary structure and high force density and is appropriate for direct-drive mechanical press....     

Examining the misalignment of a linear guideway pair on a feed drive system under different ball screw preload levels with a cost-effective MEMS vibration sensing system

This paper presents an innovative and cost-effective scheme for examining on line the degree of misalignment of a pair of linear guideway rails in a feed drive system. Prototype MEMS-based vibration detection modules were constructed and installed on the ball screw nut and linear guideway block. The ball screw preload was adjusted with four settings by changing ball sizes in this feed drive system. For each preload setting, a linear guideway rail was adjusted using feeler gauges to produce 11 misalignment statuses. The y-axis deviation caused by misalignment along the feed direction (x-axis) was measured with a dial gauge. For each preload and misalignment setting, the vibration signal was ascertained from the installed detection modules while the work table was driven by the controller. By analyzing the vibration signals from the detection module on the linear guideway block, we found that the characteristic frequency in a specific spectrum band could be used as a misalignment index. The characteristic frequencies exhibited a descending trend when the deviation was less than 40 μm and an increasing trend when the deviation was 40–120 μm. These findings demonstrate the feasibility of using cost-effective sensing units to examine the parallelism or distinguish the deviation between the linear guideway rails without disassembling the work table. This could be valuable for machine intelligence applications in the automation industry.     

Controller design for a class of nonlinear MIMO coupled system using multiple models and second level adaptation

In this paper, an adaptive control method using multiple models with second level adaptation is proposed for a class of nonlinear multi-input multi-output (MIMO) coupled systems. Multiple estimation models are used to tune the unknown parameters at the first level. The second level adaptation provides a single parameter vector for the controller. A feedback linearization technique is used to design a state feedback control. The efficacy of the designed controller is validated by conducting real time experiment on a laboratory setup of twin rotor MIMO system (TRMS). The TRMS setup is discussed in detail and the experiments were performed for regulation and tracking problem for pitch and yaw control using different reference signals. An Extended Kalman Filter (EKF) has been used to observe the unavailable states of the TRMS.