Steer-by-Wire (SBW) systems are being adapted widely in semi-autonomous and fully autonomous vehicles. The main control challenge in a SBW system is to follow the steering commands in the face of parametric uncertainties, external disturbances and actuator delay; crucially, perturbations in inertial parameters and damping forces give rise to state-dependent uncertainties, which cannot be bounded a priori by a constant. However, the state-of-the-art control methods of SBW system rely on a priori bounded uncertainties, and thus, become inapplicable when state-dependent dynamics become unknown. In addition, ensuring tracking accuracy under actuator delay is always a challenging task. This work proposes two control frameworks to overcome these challenges. Firstly, an adaptive controller is proposed to tackle the state-dependent uncertainties and external disturbances in a typical SBW system without any a priori knowledge of their structures and of their bounds. The stability of the closed-loop system is studied analytically via uniformly ultimately bounded notion and the effectiveness of the proposed solution is verified via simulations against the state-of-the-art solution. While this proposed controller handles the uncertainties and external perturbations, it does not consider the actuator delay which sometimes result in decreased accuracy. Therefore, a new adaptive-robust control framework is devised to tackle the same control problem of an SBW system under the influence of time-varying input delay. In comparison to the existing strategies, the proposed framework removes the conservative assumption of a priori bounded uncertainty and, in addition, the Razumikhin theorem based stability analysis allows the proposed scheme to deal with arbitrary variation in input delay. The effectiveness of the both controllers is proved using comparative simulation studies.
翻译:在半自主和完全自主的车辆中,SBW系统的主要控制挑战是在面临参数不确定性、外部扰动和动因延迟的情况下,跟踪指导指令;关键的是,惯性参数和阻力的扰动引发了国家依赖的不确定性,这些不确定性无法先验地被固定状态所约束。然而,SBW系统最先进的控制方法依赖于事先受约束的不确定性,因此,当依赖国家的动态变得未知时,无法适用。此外,在操作者延迟的情况下,确保跟踪运行过程中的准确性总是一项具有挑战性的任务。这项工作提出了克服这些挑战的两个控制框架。首先,提议一个适应性控制器在典型的SBW系统中应对依赖状态的不确定性和外部干扰,而没有事先了解其结构及其界限。闭路系统的稳定通过统一、最终受约束的变异性概念加以分析研究,拟议解决方案的有效性通过对州-时间框架的模拟来验证。在SBFI的延迟性分析中, 拟议的RBFIFL的稳定性分析可以不考虑。在S-CLA结果中, 拟议的S-Crental 。在S-dealalalal laderal laveal lading acal macal be tral lading in the lading the the ruder ruder lading the lading the ruder lading the lading the laut the ruder trevtal trevtal dection the ladal be trevtal restal restal restal restal laveal restaltraction restal dection the lading the restal dection the lating the lautction the lading the ladal ladal ladal ladal lautal ladal ladal ladal ladal ladal ladal ladal ladal ladal ladal ladal lad ladal ladal ladal ladal lad ladal ladal ladal ladaldaldaldaldaldal ladal ladal ladal