发布时间 : 星期五 文章汽车的转向控制汽车车辆外文文献翻译、中英文翻译、外文翻译更新完毕开始阅读86ee7ee4d0f34693daef5ef7ba0d4a7302766c1e
caught by surprise and very often reacts in the wrong way, steering too much. Oversteering, ITT's Graber explained, causes the car to fishtail, throwing the vehicle even further out of control. ASMS sensors, he said, can quickly detect the beginning of a skid and momentarily activate the brakes at individual wheels to help return the vehicle to a stable line.
It is important that stability control systems be user-friendly at the limit of adhesion - that is, to act predictably in a way similar to normal driving.
The biggest advantage of stability control is its speed - it can respond immediately not only to skids but also to shifting vehicle conditions (such as changes in weight or tire wear) and road quality. Thus, the systems achieve optimum driving stability by changing the lateral stabilizing forces.
For a stability control system to recognize the difference between what the driver wants (desired course) and the actual movement of the vehicle (actual course), current cars require an efficient set of sensors and a greater computer capacity for processing information.
The Bosch VDC/ESP electronic control unit contains a conventional circuit board with two partly redundant microcontrollers using 48 kilobytes of ROM each. The 48-kB memory capacity is representative of the large amount of \required to perform the design task, van Zanten said. ABS alone, he wrote in the SAE paper, would require one-quarter of this capacity, while ABS and traction control together require only one half of this software capacity.
In addition to ABS and traction control systems and related sensors, VDC/ESP uses sensors for yaw rate, lateral acceleration, steering angle, and braking pressure as well as information on whether the car is accelerating, freely rolling, or braking. It obtains the necessary information on the current load condition of the engine from the engine controller. The steering-wheel angle sensor is based on a set of LED and photodiodes mounted in the steering wheel. A silicon-micromachine pressure sensor indicates the master cylinder's braking pressure by measuring the brake fluid pressure in the brake circuit of the front wheels (and, therefore, the brake pressure induced by the driver).
Determining the actual course of the vehicle is a more complicated task. Wheel speed signals, which are provided for antilock brakes/traction control by inductive wheel speed sensors, are required to derive longitudinal slip. For an exact analysis of possible movement, however, variables describing lateral motion are needed, so the system must be expanded with two additional sensors - yaw rate sensors and lateral acceleration sensors.
A lateral accelerometer monitors the forces occurring in curves. This analog sensor operates according to a damped spring-mass mechanism, by which a linear Hall generator transforms the spring displacement into an electrical signal. The sensor must be very sensitive, with an operating range of plus or minus 1.4 g.
YAW RATE GYRO
At the heart of the latest stability control system type is the yaw rate sensor, which is similar in function to a gyroscope. The sensor measures the speed at which the car rotates about its vertical axis. This measuring principle originated in the aviation industry and was further developed by Bosch for large-scale vehicle production. The existing gyro market offers two widely different categories of devices: $6000 units for aerospace and navigation systems (supplied by firms such as GEC Marconi Avionics Ltd., of Rochester, Kent, U.K.) and $160 units for videocameras. Bosch chose a vibrating cylinder design that provides the highest performance at the lowest cost, according to the SAE paper. A large investment was necessary to develop this sensor so that it could withstand the extreme environmental conditions of automotive use. At the same time, the cost for the yaw rate sensor had to be reduced so that it would be sufficiently affordable for vehicle use.
The yaw rate sensor has a complex internal structure centered around a small hollow steel cylinder that serves as the measuring element. The thin wall of the cylinder is excited with piezoelectric elements that vibrate at a frequency of 15 kilohertz. Four pairs of these piezo elements are arranged on the circumference of the cylinder, with paired elements positioned opposite each other. One of these pairs brings the open cylinder into resonance vibration by applying a sinusoidal voltage at its natural frequency to the
transducers; another pair, which is displaced by 90 degrees, stabilizes the vibration. At both element pairs in between, so-called vibration nodes shift slightly depending on the rotation of the car about its vertical axis. If there is no yaw input, the vibration forms a standing wave. With a rate input, the positions of the nodes and antinodes move around the cylinder wall in the opposite direction to the direction of rotation (Coriolis acceleration). This slight shift serves as a measure for the yaw rate (angular velocity) of the car.
Several drivers who have had hands-on experience with the new systems in slippery cornering conditions speak of their cars being suddenly nudged back onto the right track just before it seems that their back ends might break away.
Some observers warn that stability controls might lure some drivers into overconfidence in low-friction driving situations, though they are in the minority. It may, however, be necessary to instruct drivers as to how to use the new capability properly. Recall that drivers had to learn not to \
Although little detail has been reported regarding next-generation active safety systems for future cars (beyond various types of costly radar proximity scanners and other similar systems), it is clear that accident-avoidance is the theme for automotive safety engineers. \Graber. \control technology dovetails nicely with the tremendous strides that have been made to the physical structure and overall capabilities of the automobile.\next such safety system is expected to do the same.
汽车的转向控制
控制系统稳定性是针对提高驾驶安全性提出的一系列措施中最新的一个。这个系统能够在40毫秒内实现从制动开始到制动恢复的过程，这个时间是人的反应时间得七倍。他们通过调整汽车扭矩或者通过应用汽车左侧或右侧制动，如果需要甚至两者兼用，来实现准确的行车路线。这个系统已被应用于奔驰S600汽车了。
稳定的机械自动系统能够在制动时发现肇端，并且在驾驶人员发现能够反应以前实现车辆的减速。
安全玻璃，安全带，撞击缓冲区，安全气囊，ABS系统，牵引力控制系统还有现在的稳定调节系统。汽车安全系统的连续升级，已经产生了一种为保护汽车所有者安全的设计模式。稳定调节系统帮助驾驶员从不可控制的曲线制动中解脱出来，从而避免了汽车的摆动滑行和交通事故。
利用计算机和一系列传感器，稳定调节系统能够检测到制动轮的打滑并且比人更快的恢复对汽车的方向控制。系统每百万分之一秒作出一次快速捕捉，以及断断汽车是否在按照驾驶员的路线行驶。如果检测到汽车行驶路线和驾驶员驾驶路线存在一个微小的偏差 ，系统会在瞬间纠正发动机扭矩或者应用汽车左右制动。过程的标准反应时间是40毫秒----人的平均反应时间的七分之一。
罗伯特博世工程系统负责人安东·范·桑特解释说：“一个稳定的控制系统能够‘感觉到”驾驶员想要运动的方向，通过控制转向角度，油门踏板的位置，制动板的状态来确定汽车实际运动路线的偏航比率（汽车偏离方向轴的角度）和横向加速度”。项目负责人阿明·马勒领导着范桑特的工作小组和奔驰汽车公司的工程师发明了第一个完全有效的稳定调节系统，该系统由发动机扭矩控制系统，制动系统，牵引控制系统组成以实现理想与现实运动之间的最小差距。
汽车安全专家相信稳定调节系统能够减少交通事故的发生，至少是在伤亡严重的事故方面。安全统计表明，多数的单车撞击事故伤亡（占伤亡事故发生的4%），事故能够通过应用这项新技术避免。这项新系统的额外费用主要用于一系列目前汽车日益普遍应用的制动/牵引控制锁组件。