谐波齿轮精确间隙分析可视化仿真

研究谐波齿轮传动优化问题,渐开线齿廓代替齿轮共轭齿廓时,存在齿轮重叠干涉影响精度问题。为保证齿轮既不发生干涉又能实现精确传动,且提高计算精度与收敛速度,提出根据齿顶干涉检验法的自动优化算法。通过图形界面参数化设计进行迭代计算,快速精确计算出最小啮合间隙,并对齿廓啮合过程进行了可视化仿真。结果表明,优化结果啮合状况良好,明显提高了计算精度与收敛速度。最后,通过大量实例分析,得到齿轮啮合过程中最容易发生干涉的转角,并采用变位修正法进行修正。为谐波齿轮加工与检验提供参考依据。     

基于传动误差数据的齿轮误差检测方法与系统

齿轮传动误差影响齿轮传动精度和平稳性,传动误差与齿距和齿廓偏差等齿轮误差数据有直接关系.利用单面啮合测试和虚拟仪器原理,构建了传动误差检测系统,研究了传动误差与齿距与齿廓偏差数据的关系,找到一种将齿距与齿廓偏差计算出来的方法.经过试验分析,验证了本方法和系统的准确性.     

光电编码器在齿轮传动误差中的应用

提出了降低传动系统转速,用光电编码器代替圆光栅测量齿轮传动误差信号的思想,对于采集的行星轮系传动误差实验数据进行了有效性的判定,用Burg算法对传动误差信号进行了功率谱密度的AR模型的参数估计,绘制出实验测得的传动误差功率谱密度曲线,对光电编码器测量传动误差结果进行了分析,证明了在低转速情况下,用光电编码器代替圆光栅测量传动误差是行之有效的。     

高速履带车辆扭杆弹簧疲劳寿命的数值计算

由于在分析高速履带车辆扭杆弹簧疲劳寿命的过程中传统方法采用静态最大载荷计算不能考虑动态载荷的影响,以多柔体动力学和有限元模态应力分析法为分析手段,通过数值仿真计算得到不同载荷作用下履带车辆扭杆弹簧的应力时间历程曲线．依据Miner线性损伤累积理论,结合车辆行驶环境和行驶工况的分配比例和扭杆弹簧材料特性曲线,采用Goodman法和Gerber法2种等效应力修正方法,对扭杆弹簧的疲劳寿命进行分析和预测,其计算结果表明Goodman法比Gerber法保守,两者之间的预测结果相差约7倍．该研究为设计阶段履带车辆关键零部件疲劳寿命预测提供可行的分析方法．     

静态与冲击载荷作用下偏斜齿轮的有限元分析

利用大型有限元分析软件ANSYS对一个因预紧力不够而偏斜的输出齿轮建立了有限元模型．利用通用ANSYS进行了静态分析，其中在施加力的载荷时．只加在1／4的齿宽上，得到了静态下的应力及变形．利用ANSYSStructural／LS-DYNA对齿轮进行了显式动力分析，得到了该齿轮在冲击载荷作用下所受到的冲击力的值，随后进行了瞬态响应的研究，得到了齿轮在冲击载荷作用下的应力和变形。通过比较可知，冲击载荷的危害是静态载荷的数倍，证实了齿轮在该工况下必然发生断裂，为齿轮的合理设计提供了依据。     

基于LS_DYNA的齿轮传动有限元动力学分析仿真

为研究齿轮传动系统的转动惯量和传动轴的扭转振动对齿轮应力变化的影响,对某齿轮传动中的1对渐开线直齿轮进行有限元动力学分析仿真．首先利用Pro／Engineering建立齿轮副的CAD几何模型;然后导入到LS_DYNA中建立齿轮副有限元模型,对齿轮副进行接触一碰撞有限元动力学分析;最后考虑该齿轮副后传动的转动惯量以及传动轴刚度对齿轮传动的影响,将转动惯量等效成质量圆盘,将传动轴等效成实体单元,建立齿轮传动等效模型的有限元动力学模型．通过分析计算得到齿轮副在模拟工况下的接触应力变化,同时获得在考虑齿轮接触、变形等情况下齿轮传动系统输入和输出的关系．结果表明,后传动输出速度和加速度明显滞后于前传动产生的速度和加速度,而且经过系统传递后,输入使得传动更加平稳．研究结果可为进一步研究齿轮传动系统的动力学特性和疲劳寿命计算提供参考．     

二级减速器齿轮传动性能分析和修形优化设计

为改善齿轮传动性能,分析某二级减速器齿轮的静强度、载荷分布和传递误差,发现其低速齿轮副的载荷分布偏载和传递误差相对较大。选取遗传算法V2,结合Romax Designer,对比分析几种齿廓修形与齿向修形的组合方式,其中最好的修形方式是将齿向鼓形修形和齿向斜度修形相结合。采取该方式对齿轮副进行优化,优化后低速齿轮副的传递误差比修形前减小92.41%,齿轮载荷分布得到改善,低速齿轮副的单位载荷降低,齿轮副的可靠性和使用寿命均提高。齿轮修形优化后的减速器传动更平稳,振动和噪声减小。     

齿轮误差快速测量系统的设计

介绍了齿轮误差快速测量系统的软、硬件设计。该系统采用啮合滚动式综合测量方法,将被测齿轮作为一个回转运动的传动元件,在理论安装中心距下与标准齿轮作啮合转动,在此过程中来测量齿轮误差。试验测试结果验证了该系统的精度。     

基于USB3.0和FPGA的传动误差检测系统的设计

为提高机床传动误差检测的速度、实时性以及精度,同时为优化硬件电路的结构,并保证采样数据毫无损失地传至上位机系统,提出了一种高速实时检测方案;通过脉冲插补的思想,提出一种传动误差检测的方法;另外在一块高性能FPGA芯片内部搭建数据预处理以及控制模块,利用USB3.0芯片作传输媒介,有效地减少了该系统外围电路复杂程度,降低了开发难度;并对该系统进行模拟仿真试验;试验结果表明:根据设定的误差曲线换算后的数据,通过另一个FPGA发送至该系统,处理后得到的数据不需要经过后期补偿,其误差曲线很好地归零并形成一条闭合曲线,而低速端转速误差曲线也正确反映了仿真实验的情况;实验结果表明该系统实现了高速实时检测,为机床传动误差检测提供了技术上的支持。     

农用拖拉机2K-H式增扭器的设计

本文对由单排2K-H型行星齿轮传动机构进行了分析。计算传动方案的传动比,根据传动比和安装条件进行配齿计算和模数选择,对行星齿轮传动进行受力分析及强度计算,并计算传动效率,输出轴的设计计算。     

Experiences of system identification applied to ship steering

Different system identification methods have been applied to determine ship steering dynamics from full-scale experiments. The techniques used include output error, maximum likelihood and more general prediction error methods. Different model structures have been investigated ranging from input-output models in difference equation form to the equations of motion in their natural form. Effects of disturbances, errors and dynamics in sensors and actuators have been considered. Programs for interactive system identification have been used extensively. The experiments have been performed both under open loop and closed loop conditions. Both linear and nonlinear models have been considered. The paper summarizes the experiences obtained from applying system identification methods to many different ships. The results have been applied both to investigate steering properties and to design autopilots for ship steering. Insight into ship steering dynamics and identification methodology has been obtained.     

一种改进的可变对角加载自适应波束形成算法

由于观测方向误差的存在,使得实际获得的方向向量与其理论值产生偏差,进而对各类自适应波束形成算法性能造成较大影响。为此提出一种有效的对角加载自适应波束形成算法,首先利用目标信号的方向向量在噪声子空间中投影最小的原理,对带有误差的方向向量进行校正,然后再使用可变对角加载原理求得对角加载因子,对实际获得的自相关矩阵进行对角加载后,形成自适应波束,从而很好地消除了方向向量误差造成的影响。算法能够有效克服目标信号对消现象,并具有良好的保形能力和快速收敛的特点。计算机仿真结果验证了这些优点。     

双桥转向摇臂机构设计方法的研究

为了使摇臂机构的参数和偏转角的函数关系能按照编写的程序进行计算机辅助设计,将空间摇臂机构简化为平面机构,研究其解析设计方法,并对摇臂机构的转化误差和转角偏差进行了计算和分析。计算实例表明,机构简化误差不超过允许值,为摇臂机构的优化设计打下了基础。     

基于最陡下降的稳健LCMV波束形成算法

针对期望信号假定导向矢量与真实导向矢量存在误差时,常规LCMV算法性能急剧下降,提出了一种针对指向误差、阵元位置误差和相位误差的基于最陡下降的稳健LCMV波束形成方法。利用最陡下降法递归搜索最优权矢量和约束导向矢量,避免了常规LCMV算法的矩阵求逆运算和变对角加载时的特征值分解,所需运算量大大降低;又因不属于对角加载,不存在加载值确定问题。仿真结果表明,新方法对期望信号导向矢量的各种误差有很好的稳健性。     

The effects of psychological load and speed on tractor operator error

Sixteen tractor operators made a total of 64 runs through a tractor driving course designed to measure operator performance in a simulated field operation. The number of tasks the operator was required to perform was held constant while speed was varied and 12.9 km/h (2 and 8 mile/h). However, the psychological load was greater at the row end. The number of steering errors highly correlated with the speed, [Formula: see text] , [Formula: see text] . The steering error rate was not evenly distributed thorughout the course, but was significantly higher at the end of the rows as the tractor entered or exited. This research on speed-load theory as it applied to complex tractor-machinery operation indicates that the number of steering errors an operator makes is directly related to speed and psychological load.     

CORRIGENDUM

The aim of this study was to assess the effects of four hours' continuous ‘ driving ’ in a ear simulator on (a) performance (number of steering errors and brake reaction time), (6) subjective fatigue, ( c) pulse rate, respiratory rate, skin resistance and neck muscle tension, ( d) intra-subject correlations between the latter variables and performance over time. An additional aim was to study these psychological and physiological measures when arousal was stimulated by the pairing of an electric shock with steering errors.

To control training effects the Ss repeated the experiment twice. The results showed that all subjects had a progressive performance decrement over time in parallel with increased feelings of fatigue. There was also a decrease in pulse rate and respiratory rate. Skin resistance showed continuous increment over time. Covariations over time between performance variables and physiological variables were rather high in most individuals; e.g. for pulse rate with frequency of steering errors, and EJ1G with frequency of steering errors. The expectation of an electric shock in connection with steering errors yielded higher subjective and autonomic arousal, slower performance decrement over time, and also lowered variability, both within and between subjects for all the variables recorded.     

Performance consequences of alternating directional control-response compatibility: evidence from a coal mine shuttle car simulator

OBJECTIVE: To investigate error and reaction time consequences of alternating compatible and incompatible steering arrangements during a simulated obstacle avoidance task. BACKGROUND: Underground coal mine shuttle cars provide an example of a vehicle in which operators are required to alternate between compatible and incompatible steering configurations. METHODS: This experiment examines the performance of 48 novice participants in a virtual analogy of an underground coal mine shuttle car. Participants were randomly assigned to a compatible condition, an incompatible condition, an alternating condition in which compatibility alternated within and between hands, or an alternating condition in which compatibility alternated between hands. RESULTS: Participants made fewer steering direction errors and made correct steering responses more quickly in the compatible condition. Error rate decreased over time in the incompatible condition. A compatibility effect for both errors and reaction time was also found when the control-response relationship alternated; however, performance improvements over time were not consistent. Isolating compatibility to a hand resulted in reduced error rate and faster reaction time than when compatibility alternated within and between hands. CONCLUSION: The consequences of alternating control-response relationships are higher error rates and slower responses, at least in the early stages of learning. APPLICATION: This research highlights the importance of ensuring consistently compatible human-machine directional control-response relationships.     

基于LQG控制的EPS系统最优控制研究

电动助力转向系统存在着路面随机激励、转矩传感器测量噪声、模型参数不确定所引起的干扰等复杂因素,通过建立电动助力转向系统的数学模型以及加入随机干扰信号的系统状态空间表达式,设计了线性二次型高斯状态反馈控制器和Kalman滤波器。并以能耗及电机的实际助力电流与目标助力电流之间的误差最小为目标函数对EPS系统进行仿真分析,仿真结果表明:采用该最优控制方法能有效的抑制系统的外部干扰,提高系统的鲁棒性,使能耗及电机的实际助力电流与目标助力电流之间的误差达到最小。     

Directional control–response compatibility of joystick steered shuttle cars

Shuttle cars are an unusual class of vehicle operated in underground coal mines, sometimes in close proximity to pedestrians and steering errors may have very serious consequences. A directional control–response incompatibility has previously been described in shuttle cars which are controlled using a steering wheel oriented perpendicular to the direction of travel. Some other shuttle car operators are seated perpendicular to the direction of travel and steer the car via a seat mounted joystick. A virtual simulation was utilised to determine whether the steering arrangement in these vehicles maintains directional control–response compatibility. Twenty-four participants were randomly assigned to either a condition corresponding to this design (consistent direction), or a condition in which the directional steering response was reversed while driving in-bye (visual field compatible). Significantly less accurate steering performance was exhibited by the consistent direction group during the in-bye trials only. Shuttle cars which provide the joystick steering mechanism described here require operators to accommodate alternating compatible and incompatible directional control–response relationships with each change of car direction.

Practitioner Summary: A virtual simulation of an underground coal shuttle car demonstrates that the design incorporates a directional control–response incompatibility when driving the vehicle in one direction. This design increases the probability of operator error, with potential adverse safety and productivity consequences.