盘式制动器制动抖动研究综述

对制动抖动现象、机理、影响因素、研究方法以及控制措施进行较全面的研究.综合抖动和噪声,寻找两者间的共性,提出应将制动抖动中涉及的相关问题整合起来协同解决.除了对制动抖动的关键因素如几何因素、材料因素进行总结,还对其它影响因素如路面状况、车辆子系统、驾驶员等进行全面的总结.最后探讨当前研究存在的主要问题和今后研究的方向和重点.     

数字智能型文创产品设计研究

目的 探索数字智能技术与文创产品结合的设计方法,为数字智能技术在文创产品的应用中提供可参考的设计范式。方法 以数字智能技术为研究切入点,通过对传感器技术、增强现实技术、增材制造等技术的分析,明晰技术应用思路;再结合数字技术原理与设计学方法归纳出数字智能型文创产品的设计方法与重点,总结出数字智能技术在文创产品创意设计、路径优化、场景融合、数字库建设、分模块组合等方面的应用方式,构建出数字智能型文创产品的设计模型。结论 数字技术与文创产品的结合可优化产品性能,推动文创产品与数字世界的高效互连,提升文创产品的智能属性并成为“活”文创。以消费者为中心的数字体验模式,可以提高文化主体的传播效率,增强文创产品的交互体验,促进文创产品的文化价值属性向数字产业链发展,从而实现最优配置。     

制动器制动温度对制动性能的影响

摩擦材料的特性决定了制动器的制动性能对温度的敏感程度,这是制动性能稳定性的主要影响因素之一。不同摩擦材料热衰退性能有较大差异,本文对采用粉末冶金摩擦材料的制动器和采用陶瓷摩擦材料的制动器进行了试验研究,对比分析了其性能差异。     

研究PID在污水处理系统电控系统中的应用

污水处理技术是一种高效利用污水回收再利用的处理技术,采用技术手段对污水进行相关处理,使得处理过的污水可以用来再次利用,从而达到节约用水的目的,减轻水资源浪费的现象。要考虑污水处理的成本和占地资源较为狭小的特点,废水处理系统的设计方案就要力求达到设备体积小,性能稳定,工程投资少的目的。与此同时,污水处理技术的工艺参数变化比较大,所以可以采用先进的PID控制技术,控制电机的输出频率,结合PLC的使用,自动切换电机的变频与工频运行,使液位保持平衡。这样可以有效地提高污水的处理能力,从而方便人们的操作和使用,提高污水处理效率。     

基于S3C2410X的车辆制动监测装置研制

根据车辆104空气制动机的参数特征,研制了一种基于S3C2410X处理器的车辆制动系统监测装置,该装置可实现车辆制动系统常见故障的检测,并对检测结果及制动系统状态数据进行大容量存储,实现对制动机维护的计算机管理。监测装置由气体压力传感器和32位嵌入式计算机两部分组成。压力传感器检测列车制动管、制动缸和工作风缸的压力值。嵌入式计算机通过对传感器提供的信息进行分析处理,实现故障的判别、显示和报警。在单车试验台上进行了车辆制动机故障模拟试验,实验结果表明,该监测装置能够实现常见制动故障的实时检测和报警。     

大空间智能消防炮现场电控系统研制

本文论述了智能消防炮的工作原理及电控系统的工作过程,针对电控系统的智能化要求设计了系统的硬件及软件。     

列车轴控防滑制动系统试验平台设计

介绍了基于压电阀的列车轴控防滑制动系统的组成及其试验平台。研究了硅压阻式压力传感器的温度 补偿技术,以满足室外长期稳定工作的需求。选择了基于霍尔效应的速度传感器并研究了传感器性能测试方法,提出了多特征参数的指纹识别方法,并应用于速度传感器的故障在线诊断。以压电阀为新型气压控制部件并实验 验证了压电阀较宽的工作环境温度范围;调速系统使试验平台可以在实验室环境中模拟列车运行状态,实现了列 车常用制动、紧急制动、防滑保护、故障诊断等试验功能。     

汽车电动助力转向系统电控单元的研究

随着电子控制技术的发展及其在汽车领域的广泛应用,电动助力转向系统(Electric Power Steering,简称EPS)越来越成为目前汽车电子技术研究的热点之一。与传统的转向系统相比,EPS系统结构简单,灵活性大,可以获得理想的操纵稳定性,能动态地适应汽车行驶状况的变化,在操纵舒适性、安全性、环保、节能、易于维修等方面也充分显示了其优越性。     

浅谈平巷人车制动距离试验的必要性

本文通过对平巷人车在实际生产中使用出现的问题,简述平巷人车制动距离试验的重要性,详细说明整个试验过程。通过对试验数据的分析,说明了问题可能的原因,并对出现原因进行了解决。     

The contribution of stereo vision to the control of braking

In this study the contribution of stereo vision to the control of braking in front of a stationary target vehicle was investigated. Participants with normal (StereoN) and weak (StereoW) stereo vision drove a go-cart along a linear track towards a stationary vehicle. They could start braking from a distance of 4, 7, or 10m from the vehicle. Deceleration patterns were measured by means of a laser. A lack of stereo vision was associated with an earlier onset of braking, but the duration of the braking manoeuvre was similar. During the deceleration, the time of peak deceleration occurred earlier in drivers with weak stereo vision. Stopping distance was greater in those lacking in stereo vision. A lack of stereo vision was associated with a more prudent brake behaviour, in which the driver took into account a larger safety margin. This compensation might be caused either by an unconscious adaptation of the human perceptuo-motor system, or by a systematic underestimation of distance remaining due to the lack of stereo vision. In general, a lack of stereo vision did not seem to increase the risk of rear-end collisions.     

盘式制动系统的非线性动力学分析

对汽车盘式制动系统建立了两自由度的非光滑动力学模型。通过数值模拟方法研究了制动盘的转速对系统动力学行为的影响。结果表明,汽车盘式制动系统存在着混沌运动和周期加倍等复杂的非线性动力学现象。     

Analysis of the stability of PTW riders in autonomous braking scenarios

While fatalities of car occupants in the EU decreased remarkably over the last decade, Powered Two Wheelers (PTWs) fatalities still increase following the increase of PTW ownership. Autonomous braking systems have been implemented in several types of vehicles and are presently addressed by research in the field of PTWs. A major concern in this context is the rider stability. Experiments with volunteers were performed in order to find out whether autonomous braking for PTWs will produce a greater instability of the rider in comparison to manual braking. The PTW's braking conditions were simulated in a laboratory with a motorcycle mock-up mounted on a sled, which was accelerated with an average of 0.35 g. The motion of the rider was captured in autonomous braking scenarios with and without pre-warning as well as in manual braking scenarios. No significant differences between the scenarios were found with respect to maximum forward displacement of the volunteer's torso and head (p < 0.05). By performing clustering analysis on two kinematic parameters, two different strategies of the volunteers were identified. They were not related to the braking scenarios. A relation of the clusters with the initial posture represented by the elbow angle was revealed (p < 0.05). It is concluded that autonomous braking at low deceleration will not cause significant instabilities of the rider in comparison to manual braking in idealized laboratory conditions. Based on this, further research into the development and implementation of autonomous braking systems for PTWs, e.g. by extensive riding tests, seems valuable.     

The effect of braking energy on the fatigue crack propagation in railway brake discs

Thermal fatigue cracks can often be found on the friction surface of brake discs used in railway vehicles after a period of usage and include crackle, radial and circumferential patterns. These cracks typically exhibit different initiation and propagation behavior under different braking conditions. In this paper, the effect of braking energy on fatigue crack evolution is analyzed by using experimental testing and numerical simulations. Macro observations show that a significant number of radial cracks appear on the surface of brake discs which operate at 300 km/h, while crackles typically appear after repeated emergency braking (EB) at 200 km/h. No crack growth was observed on disc surfaces after routine braking. The cyclic load that leads to the fatigue crack propagation consists of compressive stress during braking and residual tensile stress after cooling. Simulation results show that the depth of cracks correlates well with the residual tensile stress distribution in brake discs. Breaking tests exposed that the fracture surface of fatigue cracks which were covered by oxides shows nearly elliptic-type. Higher braking energy leads to a hardened layer on the friction surface and oxide generation near the crack edges, which are also important factors that contribute to accelerating crack propagation.     

Characterization and experiments on the friction catastrophe behaviors of brake material during emergency braking

Based on previous researches on the phenomena and mechanisms of Friction catastrophe (FC), the characterizing methods of the FC were established and the influences of braking conditions on the FC were investigated by experiments. It is found that the FC intensity, duration and starting time can be used for characterizing the FC, which reflects respectively the decreasing degree, velocity and critical time of the friction coefficient in FC. For short duration, the starting time is more practically valuable. With the increasing of initial braking velocity or braking pressure, the FC starting time becomes shorter while the FC intensity grows bigger. By comparison, the influence of initial braking velocity on the FC starting time is more obvious while the braking pressure affects the FC intensity more intensely. It is believed that the results must be valuable for further studies on the FC and can also provide a theoretical basis for reducing the occurrence of frictional failure of friction brakes.     

Effect of cellular telephone conversations and other potential interference on reaction time in a braking response

This experiment studied the effect of phone conversations and other potential interference on reaction time (RT) in a braking response. Using a laboratory station which simulated the foot activity in driving, 22 research participants were requested to release the accelerator pedal and depress the brake pedal as quickly as possible following the activation of a red brake lamp. Mean reaction time was determined for five conditions: (a) control, (b) listening to a radio, (c) conversing with a passenger, (d) conversing using a hand-held phone, and (e) conversing using a hands-free phone. Results indicated that conversation, whether conducted in-person or via a cellular phone caused RT to slow, whereas listening to music on the radio did not.     

Vehicle speed affects both pre-skid braking kinematics and average tire/roadway friction

Vehicles decelerate between brake application and skid onset. To better estimate a vehicle's speed and position at brake application, we investigated how vehicle deceleration varied with initial speed during both the pre-skid and skidding intervals on dry asphalt. Skid-to-stop tests were performed from four initial speeds (20, 40, 60, and 80 km/h) using three different grades of tire (economy, touring, and performance) on a single vehicle and a single road surface. Average skidding friction was found to vary with initial speed and tire type. The post-brake/pre-skid speed loss, elapsed time, distance travelled, and effective friction were found to vary with initial speed. Based on these data, a method using skid mark length to predict vehicle speed and position at brake application rather than skid onset was shown to improve estimates of initial vehicle speed by up to 10 km/h and estimates of vehicle position at brake application by up to 8 m compared to conventional methods that ignore the post-brake/pre-skid interval.     

状态空间控制方法在磁悬浮系统应用的研究

从增强悬浮稳定性的目的出发，根据单电磁铁的物理模型建立了磁悬浮系统在平衡点的数学模型，并且为状态控制器选择了恰当的状态模型。在此基础上对磁悬浮系统状态空间控制方法进行了理论和仿真分析，通过对结果的分析可得出状态空间控制方法能够对悬浮系统进行精确和有效稳定控制。     

Developing an inverse time-to-collision crash alert timing approach based on drivers' last-second braking and steering judgments

Drivers were asked to execute last-second braking and steering maneuvers while approaching a surrogate target lead vehicle. This surrogate target was designed to allow safely placing naive drivers in controlled, realistic rear-end crash scenarios under test track conditions. Maneuver intensity instructions were varied so that drivers' perceptions of normal and non-normal braking envelopes could be properly identified and modeled for forward collision warning timing purposes. The database modeled includes 3536 last-second braking judgment trials. A promising inverse time-to-collision model was developed, which assumes that the driver deceleration response in response to a crash alert is based on an inverse time-to-collision threshold that decreases linearly with driver speed.