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1 wheel steering 4WS
Introduction:
four-wheel steering (4WS, 4 Wheel Steering ) in addition to the traditional front wheel steering wheels, steering wheel after two rounds is that the four-wheel steering. Began to develop in the mid-1980s, its main purpose is to improve the turning radius of the car at high speed operation or stability in the lateral wind action, improve handling of light at low speed, and a reduction in the parking lot. Four-wheel steering mainly in two ways: when the steering wheel steering the front wheel steering direction at the same time referred to the same bit; sometimes referred to as a reverse position opposite to the steering wheel when the steering wheel steering direction.
Technology:
is currently used by many companies, most of which applied on large vehicles, there are some SUV and sports car has four-wheel steering function. After equipped with four-wheel steering, the vehicle can reduce the turning radius, improve the maneuverability and the low speed control and maneuverability at high speeds. We OUADRASTEER Delphi’s four-wheel steering system as an example of the four-wheel steering are introduced, it is currently one of the most advanced four-wheel steering system.
OUADRASTEER an electric shield is increased in the conventional wheel steering system based on the steering wheel. The system has four major components mdash; mdash; wheel alignment sensor, a steerable rear axle hypoid whole, a motor-driven actuator and a control unit. Wheel alignment sensor and a vehicle speed sensor continuously report data to the control unit, the control unit determines the proper angle of the rear wheels based on the data reported. By calculation, determine the correct operational phase.
The system has three main operating modes: a negative phase, phase, normal phase. When low speed. The rear wheel turning direction opposite to the front wheels, which is a negative phase. When the traveling speed, while holding the rear straight phase. highWhen the traveling speed, the rear wheel is in positive phase, and the front wheel turning in the same direction. Negative phase drag manipulation at low speeds, the tail follows the real trajectory of the vehicle more closely than the two steering. This makes driving in city traffic much easier. When the low-speed manipulation, such as a camper or trailer Ship reverse parking, OUADRASTEER will make it easier to manipulate. When the trailer down. Negative phase greatly improves the reaction of the steering operation of the trailer, the vehicle position more easily.
QUADRASTEER improve the high-speed running stability of the vehicle. Rear wheels at high speeds and steering wheel are the same, it helps to reduce vehicle skidding or torsion, the reaction equilibrium of the vehicle when overtaking, changing lanes, or both help to avoid uneven road. In addition, OUADRASTEER and four-wheel drive system is also fully compatible with, and can improve the performance of four-wheel drive system, according to the manufacturer’s requirements, both selected by the driver, but also fully automated. For example, using the selection interface, a driver under different driving conditions can be adjusted rear steering performance. Select mode includes a normal driving, towing a trailer, a two steering. If the four-wheel steering system is damaged, then, QUADRSEER system can also control back to the normal two steering mode.
System components:
The system has four major components eleven wheel alignment sensor, the steerable overall hypoid rear axle, a motor drive actuator and a control unit.
When the push button is selected wheel steering (4WS 4WS or trailer) mode, Quadrasteer system is active. Quadrasteer system is equipped with two sensors, wherein a sensor is mounted on the steering column, a steering wheel for detecting the steering angle; while the other sensor mounted on the transmission for providing a vehicle speed signal. Signals from these two sensors can be timely transmitted to the ECU. In fact, ECU is a monomer having two integrated 10MHz operating speed and microprocessor comprising memory 128K. Each microprocessor independent steering operation based on input information and the vehicle speed sensor, the system self-test function simultaneously and start to determine the system itself is functioning normally. Then, ECU order to determine whether the shift is executed correctly calculate the data by comparing two microprocessorsRow. If all goes well, then the ECU will start the rear axle steering drive motor. In this process, at a frequency of micro everywhere 0.004s / times continuously repeatedly calculates the steering angle and the steering system self-test failures. Once the four-wheel steering system, or when abnormal sensor error, rear axle steering actuator motor driving immediately and automatically aligning the rear axle, while the 4WS system is switched into the 2WS (conventional steering wheel 2) safe steering mode. Even ECU catastrophic failure during steering, the steering axle inside the rack the return spring means can be a neutral position of the rear axle slowly return, while the rear-wheel steering motor and to block off the steering wheel operation.
Advantages:
First, when the vehicle is reduced turning radius low speed steering. At low speed steering, front and rear wheels of the vehicle due to the turning radius can be reduced reverse steering percentage of 20. Four-wheel steering technology allows large vehicles have as a small car class handling agility and parking.
Second, significant improvement in high-speed driving stability. When the steering at high speeds, the rear wheel steering system and the front wheels through the same phase shift, reduce / eliminate the occurrence probability of the vehicle skidding accidents, significant improvement in high-speed driving stability and safety, in order to alleviate the driver the degree of fatigue in a variety of road conditions (especially in the rain day) high-speed driving.
again, increase the capacity of the vehicle’s trailer. By steering the rear axle of the tractor trailer steering, four wheel steering system is greatly improved trailer towing vehicle maneuverability, stability and safety.
prospects:
From the late 1980s to today, the Japanese carmaker has continued independence of the traditional four-wheel steering. But four-wheel steering is threatened electronic stability control and yaw control system, both devices are able to make the four-wheel steering system as correct understeer / oversteer without causing excessive adverse effects of increased cost and weight .
Nissan Skyline GT-R four-wheel steering is still prove valuable challenging Driving characteristics. By computer-assisted, Nissan’s super HICAS system enabled skates tightly controlled brakes, this form can be an alternative to see them through any means. When you faceWhen challenging corners, the rear wheels will be the first reverse shift, in order to enhance the sensitivity of the initial steering response. Then, when the sensor senses when the vehicle response to steering control, the steering wheel in the same direction as the front wheels, so that the rear tires introduced immediately in response to the slide, this response may facilitate the adjustment of the angle of bend attack. Because computer monitors the entire process, the amount of oversteer will remain suppressed. So now in addition to some large trucks and racing use, almost no use of passenger cars, four-wheel steering technology has greatly improved maneuverability, stability, safety and comfort of large vehicles, and is an anti-lock braking system ABS, TCS traction control system comparable to the revolution in automotive technology epochal change the future of large vehicles, and is expected in the next five years to become one of the most popular large vehicle attachments.