The force transmitted from the front tires to the steering rack of a vehicle, called the rack force, plays an important role in the function of electric power steering (EPS) systems. Estimates of rack force can be used by EPS to attenuate road feedback and reduce driver effort. Further, estimates of the components of rack force (arising, for example, due to steering angle and road profile) can be used to separately compensate for each component and thereby enhance steering feel. In this paper, we present three vehicle and tire model-based rack force estimators that utilize sensed steering angle and road profile to estimate total rack force and individual components of rack force. We test and compare the real-time performance of the estimators by performing driving experiments with non-aggressive and aggressive steering maneuvers on roads with low and high frequency profile variations. The results indicate that for aggressive maneuvers the estimators using non-linear tire models produce more accurate rack force estimates. Moreover, only the estimator that incorporates a semi-empirical Rigid Ring tire model is able to capture rack force variation for driving on a road with high frequency profile variation. Finally, we present results from a simulation study to validate the component-wise estimates of rack force.

中文翻译：

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不平路面行驶齿条力的估计与分解

从前轮胎传递到车辆转向齿条的力称为齿条力，在电动助力转向 (EPS) 系统的功能中起着重要作用。EPS 可以使用齿条力的估计值来减弱道路反馈并减少驾驶员的努力。此外，齿条力的分量（例如，由于转向角和道路轮廓而产生）的估计可用于分别补偿每个分量，从而增强转向感觉。在本文中，我们提出了三种基于车辆和轮胎模型的齿条力估计器，它们利用感测到的转向角和道路轮廓来估计总齿条力和齿条力的各个分量。我们通过在具有低频和高频剖面变化的道路上进行非攻击性和攻击性转向操作的驾驶实验来测试和比较估计器的实时性能。结果表明，对于激进的机动，使用非线性轮胎模型的估计器会产生更准确的齿条力估计。此外，只有结合半经验刚性环轮胎模型的估计器才能捕获在具有高频轮廓变化的道路上行驶时的齿条力变化。最后，我们展示了模拟研究的结果，以验证齿条力的组件估计。只有结合了半经验刚性环轮胎模型的估计器才能捕获在具有高频轮廓变化的道路上行驶时的齿条力变化。最后，我们展示了模拟研究的结果，以验证齿条力的组件估计。只有结合了半经验刚性环轮胎模型的估计器才能捕获在具有高频轮廓变化的道路上行驶时的齿条力变化。最后，我们展示了模拟研究的结果，以验证齿条力的组件估计。