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.     

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.     

The distraction effects of phone use during a crucial driving maneuver

Forty-two licensed drivers were tested in an experiment that required them to respond to an in-vehicle phone at the same time that they were faced with making a crucial stopping decision. Using test track facilities, we also examined the influence of driver gender and driver age on these dual-task response capacities. Each driver was given task practice and then performed a first block of 24 trials, where one trial represented one circuit of the test track. Half of the trials were control conditions in which neither the stop-light was activated nor was the in-vehicle phone triggered. Four trials required only stop-light response and a further four, phone response only. The remaining four trials required the driver to complete each task simultaneously. The order of presentation of specific trials was randomized and the whole sequence was repeated in a second block giving 48 trials per driver. In-vehicle phone response also contained an embedded memory task that was evaluated at the end of each trial circuit. Results confirmed our previous observation that in the dual-task condition there was a slower response to the light change. To compensate for this slowed response, drivers subsequently brake more intensely. Most importantly, we recorded a critical 15% increase in non-response to the stop-light in the presence of the phone distraction task which equates with increased stop-light violations on the open road. These response patterns varied by driver age and driver gender. In particular, age had a large effect on task components that required speed of response to multiple, simultaneous demands. Since driving represents a highly complex and interactive environment, it is not possible to specify a simplistic relationship between these distraction effects and outcome crash patterns. However, we can conclude that such in-vehicle technologies erode performance safety margin and distract drivers from their critical primary task of vehicle control. As such it can be anticipated that a causal relation exists to collision events. This is a crucial concern for all in-vehicle device designers and for the many safety researchers and professionals seeking to reduce the adverse impacts of vehicle collisions.     

轮式装载机刹车能回收系统研究

针对循环作业工况下轮式装载机刹车频率高,能量损失严重的问题,对装载机节能潜力进行分析计算,设计不同类型装载机的刹车能回收方案,并对关键元件的参数设置进行探讨,验证所设计的能量回收方案的可行性.     

封星技术在永磁同步曳引机中的应用

通过对永磁同步曳引机封星技术的论述及对封星电磁制动时电梯溜车速度的分析,发现在永磁同步曳引机中利用封星电磁制动可补充或替代某种工况下电梯机械制动的缺失,提高电梯在制动方面的安全性和可靠性。     

带式输送机新型制动系统的开发研制

介绍了带式输送机新型制动系统的研制过程及主要特点,该系统具有技术先进、性能可靠、满足计算机自动控制要求等优点。提高了带式输送机制动系统技术水平。     

起重机下坡突然没有制动的故障原因分析与排除

某型起重机下坡时突然发生没有制动故障,针对故障进行原因调查和分析.通过对起重机制动系统和加力器进行结构、原理分析,找到了故障原因,排除了设备故障隐患.     

车辆制动能量回收装置的研究

介绍了一种新型车辆制动能量回收装置的工作原理,阐述了装置的设计要求与设计方法。该装置克服了现有车辆制动装置工作时只能消耗能量而不能回收和重复利用能量的缺点。     

无极绳牵引车的制动装置的设计

详细介绍了无极绳牵引普轨制动车的制动结构、工作原理及选型计算,并对其研制工艺的关键步骤作了叙述。     

基于模糊PID的混合动力挖掘机回转制动研究

针对油电混合动力挖掘机回转的制动超调以及制动后的自锁问题,设计了一种带修正规则的模糊PID控制算法,并将该算法应用于回转制动控制。在AMESIM与MATLAB平台上运用上述控制算法对回转制动过程进行了联合仿真,仿真结果表明,设计的控制算法相对于传统的PID控制算法而言,在回转制动及停车自锁的情况下,能够较明显改善对混合动力挖掘机回转的平稳控制。该算法经实际应用后测试表明,其综合性能不但能满足实际操作要求,而且具有较好的节油性和较强的实用性。