結合路面估測及滑差控制之防鎖死煞車系統

Abstract

良好的煞車性能，需要具備有較短的煞車距離與良好的方向操控性兩個條件。為了在未知路面中達到此目的，在本論文中對於未知的路面狀況，我們藉由動態摩擦力模型(LuGre Model)所設計的路面估測器，來估測車子在煞車期間所行經的路面狀況。在非線性控制器設計方面，我們採用對系統之不確定性具有強健特性的滑動模式控制器，並且加入變動性之邊界層來減少顫抖現象。我們的控制策略是利用防鎖死煞車系統控制器，控制車輛的滑差追蹤由路面估測器所估測到的不同路面的滑差率。由模擬結果驗證對於路面估測器結合所設計出來的防鎖死煞車控制器對於未知的路面具有不錯的估測能力，而且控制器也具有不錯的追蹤能力 。

In this paper, for the unknown road conditions we design the road estimator that employ the dynamic friction model (LuGre Model) which described tire/road friction action behavior to have good braking performance including shorter stopping distance and good steering performance. The road estimator is for identifying the road conditions during the vehicle-stopping period. For the controller design, this paper adopts sliding mode control theorem because of its well-know robust for system uncertainty. In addition, in order to reduce the chattering problem caused by the sliding mode controller. The controller is modified to have a boundary layer, whose control signal varies smoothly inside the boundary layer. Our main control strategy is using the Anti-Lock Braking system’s controller to control the vehicle’s slip ratios track the variant optimal slip ratios, which obtained by road estimator. Simulation results will show the validity and effectiveness of the proposed methods.