外文翻譯----非線性pid控制在一系列卡車abs問題中的應(yīng)用(文件)
【正文】 ossible while maintaining the directional control. It is well known that the friction coefficient, μ, is a nonlinear function of the slip, S. The ideal goal for the control design is to regulate the wheel velocity, ω, such that an optimal slip, which corresponds to the maximum friction, is obtained. For the sake of simplicity, however, it is very mon in industry to set a desired slip to .2. Given the vehicle velocity, V, and the wheel radius R, the ABS control problem bees regulating ω such that the slip in () reaches a desired value, such as .2 In this paper, the control design is focused on a class of truck ABS problems, which pose a few unique challenges, different from passenger cars. 1. The actuator of the truck ABS is a pneumatic brake system, which is typically slower in response and harder to control than a hydraulic brake system. The control action of the brake system is discrete. The brake pressure is controlled by discrete valves (open or close). The brake pressure can be controlled to increase, hold constant or decrease. Through PWM (Pulse Width Modulation), the actions of the discrete valves are mapped into a continues analog control signal ranging from –1 to +1, where –1 means fully exhausting pressure, +1 means fully building up pressure and 0 means holding pressure as constant. 2. The measurement of the brake pressure is not available, which makes the control of the pneumatic brake system even more difficult. The ABS controller must deal with the brake dynamics and the wheel dynamics as a whole plant. 3. The measurement of the vehicle velocity or vehicle acceleration is not available. The only feedback signals are two or four channels of wheel angular velocity. It poses a challenging problem for the vehicle velocity estimation since the vehicle velocity is necessary to set the wheel reference velocity. A separate study was carried out to resolve this issue in [2]. 4. The plex dynamics of the tractor/trailer system and the large variations of the truck operation condition set a very stringent requirement for the ABS controller. The tuning and testing of a truck ABS are also much more difficult than an ABS for passenger cars. Current Technology Various control strategies have been implemented in real ABS products or discussed in publications. Since the tec
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