共查询到16条相似文献,搜索用时 93 毫秒
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在机车牵引控制系统中,是通过粘着控制实现车轴牵引转矩的控制。在传统的粘着控制方法中,由于不同路况下控制参数固定会导致机车牵引力损失过多,为优化轮轨间的粘着利用,提高机车的牵引力,提出了一种模糊路况识别的粘着控制方法,通过观测器观测到的粘着系数以及机车车轴参考速度估算模块计算的蠕滑速度模糊识别机车的运行路况,根据不同路况调整相应的空转判别参数以及牵引转矩输出函数。建立电力机车模型来验证方法的有效性,仿真结果表明,改进的粘着控制方法减少了牵引力的损失,提高了粘着利用效率,为电力机车的牵引运行提供更高的牵引力。 相似文献
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研究电力机车粘着控制中滤波环节设计优化的问题.在电力机车的粘着控制研究中,传统滤波环节操作繁琐,依靠运行实验反复调试,对控制程序改动大导致实验成本较高,没有形成有效的设计方法.为克服上述问题,采用MATLAB工具与FPGA平台相结合的计算机辅助设计方法,解决了实验中滤波环节的设计问题.利用FDATools设计所需要的滤波器并结合Fdesign实现数据定点化,之后利用Simulink-Modelsim联合仿真并转换Vefilog HDL代码,在FPGA平台上得以实现.仿真结果表明,上述方法在保证了良好滤波效果的基础上,大幅缩短设计时间,使得在车辆实验中便于快速修改,同时也为后续的粘着控制板卡制作提供了理论参考. 相似文献
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位置传感器的引入,使得开关磁阻电机(SRM)结构复杂,可靠性降低,研究了非导通相注入脉冲的转子位置估计方法,该方法不受电机控制方式,以及绕组电流超越饱和阈值的影响.针对响应脉冲电流产生的扰动转矩,设计了基于脉冲注入法的开关磁阻电机转矩优化系统.通过转速环将转矩差转换为给定转矩,建立合理的转矩分配机制,得到给定相转矩,并将直接瞬时转矩控制(DITC)与电流闭环控制相结合使转矩准确吻合给定相转矩,从而实现电机的循环控制,有效减小了脉冲电流产生干扰转矩对转矩波动的影响.建模仿真验证了方法的可行性:对基于脉冲注入的无位置传感器开关磁阻电机的转矩脉动具有良好的抑制效果. 相似文献
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工业机器人是我国制造业转型升级的核心技术,作为其关键组成部分之一的关节电机需要解决机器人运行中的高精度、平稳性等问题.为保证关节电机输出转矩的稳定性,合理的电机本体设计及参数优化显得尤为重要.根据关节电机的设计需求,提出了12/29极磁通反向电机的初步设计方案,确定了样机的主要尺寸.在此基础上,使用Matlab语言编写电机仿真和优化程序,基于FEMM有限元计算工具,对样机的电磁性能进行了有限元验证,并以负载转矩波动率为优化目标,采用随机探索法对电机尺寸进行了多参数优化.优化后的样机达到了设计指标,能够较好地满足工业机器人用关节电机的要求. 相似文献
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The detachment of a single rigid sphere in a cylindrical PDMS microchannel has been investigated for systems where the particle
occupies greater than 50% of the channel cross-sectional area. The fluid velocity required to detach a particle adhering to
a microchannel wall is a function of many variables; however, only the effect of particle size is considered in this paper.
Experiments were performed for Reynolds numbers less than 0.1, and the ratio of particle diameter, d
p, to channel dimension, D, was varied from 0.50 to 0.95 in a 230 μm channel. A nonionic surfactant (Tween 80) was used to minimize the effect of adhesive
forces other than van der Waals forces. In addition, a simple force-balance model based on particle lift, buoyancy, drag,
gravitational forces, and adhesion due to van der Waals forces has been developed to predict the velocity required for particle
detachment. The predicted and experimentally measured velocities agree relatively well within the limit of experimental error.
The detachment velocity was qualitatively found to increase with decreasing d
p
/D. 相似文献
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For non-wetting liquids the contact angle with a rough surface is greater than with a flat surface and may approach 180°, as reported for leaves of water-repellent plants, such as lotus. Roughness affects the contact angle due to the increased area of solid–liquid interface and due to the effect of sharp edges of rough surfaces. High roughness may lead to composite solid–liquid–air interface, which may be either stable or unstable. A comprehensive analytical model is proposed to provide a relationship between local roughness and contact angle, which is used to develop roughness distribution and to create biomimetic superhydrophobic surfaces. Various roughness distributions are considered, including periodic and surfaces with rectangular, hemispherically topped cylindrical, conical and pyramidal asperities and the random Gaussian height distribution. Verification of the model is conducted using experimental data for the contact angle of water droplet on a lotus leaf surface. For two solid bodies in contact, for wetting liquids, wetting leads to the meniscus force, which affects friction. Dependence of the meniscus force on roughness, previously ignored, is considered in the paper and it is found that with increasing roughness meniscus force can grow due to scale effect.
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Bharat BhushanEmail: Phone: +1-614-2920651Fax: +1-614-2920325 |
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蚂蚁等生物体微小吸附力的研究对吸湿类机器人的研制有着重要意义.按照微小吸附力测试系统的要求,针对关键步骤--检测蚂蚁何时飞出测试平台展开研究.采用了时态差分法检测蚂蚁的吸附状态,判断其是否飞出测试平台.为降低误判率,设计了三次差分图像检测算法.通过算法的实现和在测试系统上的试验,验证了算法的有效性,准确测得了所选蚂蚁飞离平台时伺服马达转速为1795rpm.这为微小生物吸附力进一步研究铺平了道路. 相似文献
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研究粘连细胞图像的分割问题。针对医学细胞图像中,细胞经常发生粘连,细胞粘连部分由于发生像素灰度混合,造成图像不清晰。传统的应用灰度的分割算法由于不能很好的区分粘连部分的灰度,不能完整的分割细胞的问题。为了解决上述问题,提出了自适应阀值调整的粘连细胞分割方法。通过求得粘连部位的细胞像素的具体特征,运用阀值的自适应变化区分粘连部位像素之间的不同,对像素进行划分,克服了传统方法像素划分不清的弊端。实验表明,方法能够有效的分割医学图像中的粘连细胞,取得了比较好的效果。 相似文献
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Giovanna Zilibotti Mauro Ferrario Carlo Maria Bertoni Maria Clelia Righi 《Computer Physics Communications》2011,(9):1796-1799
The system consisting of two diamond (001) surfaces in contact was studied by means of plane-wave/pseudopotential density functional calculations. Different hydrogen coverages, ranging from fully hydrogenation to bare surfaces, were considered. The adhesion energy was calculated as a function of both the separation and the lateral displacement of the two surfaces. The effects of dangling carbon bonds on the adhesion and potential corrugation are quantitatively discussed. 相似文献