共查询到19条相似文献,搜索用时 109 毫秒
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基于整车转向模型的汽车主动悬架控制研究 总被引:3,自引:0,他引:3
针对汽车主动悬架系统在转向过程中的动力学行为,建立了整车转向模型。从提高汽车转向时的乘坐舒适性和操纵稳定性出发,从时域和频域两方面研究了整车系统的最优控制问题。考虑转向过程中汽车的横摆、侧倾、俯仰及垂直方向的振动和悬架的动挠度,定义了范数评价指标,并根据人体对振动的敏感频率范围引入了适当的频域加权函数,设计出最优控制器。仿真结果表明,该方法能够有效抑制由转向和路面不平引起的振动,明显降低人体敏感频段的垂直和旋转方向振动的幅值,使悬架动挠度有所下降。 相似文献
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基于状态识别的整车操纵性和平顺性的协调控制 总被引:3,自引:1,他引:3
建立汽车底盘中悬架、制动系统及转向时的操纵动力学模型,分析各个系统运动关系之间的相互影响.为改善车辆在多工况下的平顺性和操纵性,在设计出基于状态识别的协调控制器的基础上,对悬架、转向和制动系统分别采用PID、滑模变结构和变滑移率逻辑门限值的控制方法,并对不同工况下车辆运动信息进行控制分类,同时通过大量的仿真对各控制参数进行调试,设计出最佳的控制参数值.在此基础上,设计出整车三个控制系统软硬件,进行状态识别模式下的汽车底盘控制系统实车试验.结果表明,该方法在复杂工况下能够有效地抑制车身的垂直振动、俯仰和侧倾,极大地改善整车的平顺性;车辆转向或转向制动时,直接横摆力矩控制器能够根据上层协调器的信息,较好地跟踪车身的目标横摆角速度,提高整车的操纵稳定性;制动子系统控制器能够根据上层协调器提供的实时目标滑移率,控制车轮获得最大制动力,缩短制动距离,提高了制动性能. 相似文献
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在车辆行驶平顺性的研究中,为弥补传统数学建模方法不能完全反映实际整车行驶动态特性的缺点,以多体动力学仿真软件SIMPACK为平台,建立昌河某微型轿车的整车多体动力学模型.利用MATLAB设计半主动悬架模糊控制器,并进行联合仿真分析.仿真结果表明:车速为40km/h时,与被动悬架系统相比,车身垂直加速度、车身俯仰角速度标准差和峰值分别降低了10.76%、18.03%、20.48%、12.13%.有效衰减了车体振动,缓和了路面的振动冲击,改善了整车行驶平顺性,提高了乘坐舒适性. 相似文献
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在常规平路起步和坡道空档起步工况下开展汽车制动颤振整车道路试验,分析制动颤振的瞬态动力学特性。设计汽车制动颤振关键因素试验,研究动力总成、制动器总成、悬架总成对制动颤振的影响。研究表明,汽车制动颤振包括两种典型的运动模式,一是具有持续时间短、宽频带特征的冲击振动,没有明确的极限环;二是具有持续时间长、多倍频特征的周期谐波振动,它属于一种典型的粘滑振动,具有明显的极限环。制动压力是汽车制动颤振发生的关键触发条件,制动压力以较大斜率下降至特定范围时,往往触发冲击振动为主的制动颤振;反之,则容易触发周期谐波振动为主的制动颤振。汽车动力总成驱动力和发动机转速波动是制动颤振的关键影响因素,合理设计发动机从低温到常温的加浓控制策略和起步时的动力总成控制策略,可有效地抑制制动颤振。制动器动、静摩擦因数差值是制动颤振重要的影响因素,制动块背板与保持架的连接刚度、制动钳质量也是关键因素。通过制动器总成结构参数设计改变颤振时制动器的振动模式,改善制动中的悬架弓形效应,为控制制动颤振提供了新思路。 相似文献
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建立汽车制动时的4自由度动力学模型,并利用仿真方法研究汽车动态特性.研究表明,即使当路面为简谐的情形,车身与轮子的振动均为非简谐的,甚至不是周期的.汽车的结构参数对其整车的振动影响是剧烈、不同和复杂的,合理选择有关结构参数,如距离l1、悬架弹簧刚度等,可以使车身的振动很小.道路表面的波长也会影响汽车的振动且扮演着变频激励的作用. 相似文献
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电梯的振动是乘运质量的重要因素之一,拉格朗日方程是振动理论的基础。通过推导拉格朗日方程,建立常见两种曳引比(1∶1和2∶1)曳引驱动电梯悬挂系统垂直方向的动力学模型,分别得出3自由度和7自由度的动力学微分方程。通过建立垂直方向动力学模型,为后续运用Matlab进行模态分析,推导关键参数对电梯振动的影响规律建立了理论基础。 相似文献
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分析了在斗轮机空载、取料、堆料的三种工况下,俯仰运动液压缸受力状况。针对斗轮机俯仰运动受力特点,提出了斗轮机俯仰液压系统的改进方案,以解决斗轮机臂架振动问题。 相似文献
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为了研究盘式制动系统参数对制动颤振的影响,建立了二自由度的动力学模型,利用Matlab进行数值仿真,分别研究了制动初速度、制动压力、阻尼和刚度等因素对制动系统动力学特性的影响。根据得到的位移曲线和相图可以看出:随着制动初速度的增大,系统黏滞阶段持续时间减少,并逐渐进入稳定运动状态;制动压力相对较小时,制动系统处于稳定状态,随着制动压力的增大,摩擦片和制动盘的振动幅值也随之增大,振动强度变大;在阻尼增大的过程中,摩擦片和制动盘均由起初的纯滑动运动状态进入稳定运动状态,且达到稳定运动状态的时间也逐渐缩短;摩擦片在相对较小的制动刚度下即可达到稳定状态,而制动盘则需要有较大的刚度才能达到稳定状态。 相似文献
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汽车制动性能良好是汽车安全行驶的重要保证。汽车在行驶过程中因制动跑偏而导致车祸,是许多交通事故主要原因之一。了解、分析汽车制动跑偏的主要因素,迅速地找出故障原因,给予排除以确保行车安全。首先分析汽车制动跑偏的主要原因,然后重点分析前轴总成对汽车制动跑偏的因素和在生产过程中的改进措施。 相似文献
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Mingming Xing Xiaoguang Li Kaifeng Xue Chengmao Zhang Zongxiang Hou 《Journal of Mechanical Science and Technology》2020,34(4):1485-1493
The stability of a high clearance sprayer (HCS) can be considered in developing modern agriculture. We built a three-dimensional dynamics model of HCS with road excitation considering the influence of complex terrain on the whole vehicle vibration. The numerical simulation method was proposed to solve differential equations based on the Newmark-ß method. The response curves of whole vehicle in the time and frequency domain response were analyzed. The simulation results show that the vibration amplitude difference of left and right wheel is bigger than amplitude difference of right and rear wheel. The average amplitude of roll motion is bigger than pitching motion. The reason is that since the man-machine seat is set on the left of whole vehicle, an additional roll torque is brought. Besides, the displacement amplitude of whole vehicle is bigger than man-machine seat. The reason is that the vibration absorption system of seat can reduce vibration effectively. In amplitude-frequency response curves, the multiple resonance points occur with the road excitation given in this paper. The maximum response amplitude of angle velocity and acceleration of pitching motion is bigger than roll motion. This study has an important theoretical and practical value for structure dynamic optimization of HCS. 相似文献
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G S Paddan M J Griffin 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》1992,206(3):159-168
Head motion has been measured in six axes on twelve subjects exposed to vertical seat vibration in the frequency range 0.5-25 Hz. The subjects sat on a rigid flat seat in two postures: 'back-off' (no backrest) and 'back-on' (subject's back in contact with the seat backrest). Translational acceleration has been calculated for various locations on the head and transmissibilities between vertical seat vibration and translational head motion determined for each location and all axes. The translational motion of the head was most affected by pitch motion of the head. This caused variations in fore-and-aft motion with position along the vertical axis of the head and variations in vertical motion with position along the fore-and-aft axis of the head. These variations are illustrated for each subject in both postures. The individual data allow the identification of various modes of vibration and show that seat-to-head transmissibility is greatly affected by pitch modes of the head and neck. The magnitude of motion occurring in some modes is dependent on body posture. 相似文献
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Hydraulic brakes are the most important components in automobile. It requires advanced supervision and fault diagnosis to improve the safety of passenger, reliability and economy. Condition monitoring is one of the major division through which the reliability of such components could be monitored. The condition of the brake components can be monitored by using the vibration characteristics which will reveal the condition of the brake systems. In this paper machine learning algorithm using vibration monitoring is proposed as a possible solution to this problem. From the hydraulic brake test set up, the vibration signals were acquired by using a piezoelectric transducer and data acquisition system. C4.5 decision tree algorithm was used to extract statistical features from vibration signals. Feature selection was also carried out. Since no much of methodologies are available to find the effective number of features for a given problem, a detailed study is needed to find the best possible number of features. Hence the effect of number of features was studied by using decision tree. The selected features were classified using C4.5 decision tree algorithm and Best first decision tree algorithm with pre pruning and post pruning techniques. The results are discussed and conclusions of the study are presented. 相似文献