###### Abstract  
This research aims to investigate steering feel by analyzing a steering system and an electric power steering logic. First, steering feel is defined based on previous research, and methods for evaluating it are discussed. Second, a sensitivity analysis is conducted by modeling our developed vehicle and that of a competitor known for its excellent steering feel via a multi-body simulation. We then propose a straightforward method to determine the parameters associated with steering feel to achieve the desired steering characteristics. Last, by modifying the electric power steering control system, we achieve a steering feel in our vehicle that matches the desired steering characteristics. steering feel; electric power steering; reverse engineering; vehicle dynamics +
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the lateral characteristics of the vehicle was implemented, allowing for an interpretation from the perspective of the entire vehicle, rather than one limited to the steering system. However, according to [2], the elasticity of vehicle components influences handling characteristics. Especially in the on-center area, where factors such as the steering column and friction and chassis elasticity have an impact on the steering characteristics, considering these factors in the simulation environment is crucial in establishing reliable simulation models. In [13], a notable study, the authors implemented a full vehicle model in a multi-body simulation environment and conducted model validation to ensure the reliability of both the vehicle and steering system model. Using the validated model, the electric power steering (EPS) control system was tuned to achieve the same level of steering feel as the target vehicle. However, they did not analyze the target vehicle. This means that they could not suggest which component should be modified in the next stage, as the desired steering feel could not be achieved through EPS controller tuning. Moreover, they did not mention which features of the EPS controller were tuned and how this was performed. Therefore, we extend these previous works, including the one mentioned above, by analyzing the reasons for the differences in steering feel between our vehicle and a competitor's vehicle. Based on this analysis, we suggest a method to design the EPS controller so that its steering feel matches that of the target vehicle. Additionally, by identifying the individual impact of major factors affecting steering feel, we provide various options for modifying the steering feel. Steering feel refers to the sensation experienced by a driver when performing steering actions. It is subjective and dependent on the driver's preferences. In [12], subjective expressions of steering feel were defined. Specifically, the factors contributing to a trained driver negatively perceiving \"inertia feel\" remain unclear. Even if engineers identify the factors, how they can be improved and to what extent remain unclear. Therefore, steering feel should be quantified and defined, which will serve as the criteria for setting improvement methods and goals. In 1984, [PERSON] proposed experimental evaluation standards [14], known as the steering feeling index for the on-center handling area, by measuring the steering wheel angle, steering torque, and lateral acceleration. The measured values were obtained by inputting steering angles at a frequency of 0.2 Hz, which resulted in a lateral acceleration of approximately 0.2 g. Thereafter, other studies expanded on [PERSON]'s proposal by introducing refined indices, as listed in Table 1.  
In [15], the authors aimed to quantify vehicle handling by utilizing the time lag between steering angle and yaw rate. However, this approach was not widely adopted in subsequent studies. It was more common to use lateral acceleration to evaluate vehicle response. In [16], the authors interpreted the impact of roll rate on steering feel by considering changes caused by vehicle motion.