Steering Feedback in Dynamic Driving Simulators: Road-Induced and Non-Road-Induced Harshness

TL;DR

This paper addresses how steering feedback in driving simulators is perceived when considering high-frequency content between $30$ and $100$ Hz. It uses a controlled back-to-back design comparing a reference EPS-equipped vehicle to four simulator variants, isolating road-induced and non-road-induced excitations via different tire models and SST excitations. The key finding is that non-road-induced excitations substantially improve subjective ratings of steering and chassis feedback, with the physics-based FTire model combined with active SSTs (variant V3) yielding the closest match to the reference. Road-induced high-frequency content showed smaller effects, highlighting the importance of non-road excitations and high-fidelity tire representations for realistic steering feel in dynamic simulators.

Abstract

Steering feedback plays a substantial role in the validity of driving simulators for the virtual development of modern vehicles. Established objective steering characteristics typically assess the feedback behavior in the frequency range of up to 30 Hz while factors such as steering wheel and vehicle body vibrations at higher frequencies are mainly approached as comfort issues. This work investigates the influence of steering wheel and vehicle body excitations in the frequency range between 30 and 100 Hz on the subjective evaluation of steering feedback in a dynamic driving simulator. A controlled subject study with 42 participants was performed to compare a reference vehicle with an electrical power steering system to four variants of its virtual representation on a dynamic driving simulator. The effects of road-induced excitations were investigated by comparing a semi-empirical and a physics-based tire model, while the influence of non-road-induced excitations was investigated by implementing engine and wheel orders. The simulator variants were evaluated in comparison to the reference vehicle during closed-loop driving on a country road in a single-blind within-subjects design. The subjective evaluation focused on the perception of road feedback compared to the reference vehicle. The statistical analysis of subjective results shows that there is a strong effect of non-road-induced steering and vehicle body excitations, while the effect of road-induced excitations is considerably less pronounced.

Figures (5)

• Figure 1: The Advanced Vehicle Driving Simulator (aVDS) at the IFM of Kempten University of Applied Sciences on a section of the reference track
• Figure 2: Spectrograms of measured steering wheel accelerations vs. distance traveled. \ref{['fig_AlgoPerformance_ref']} Reference vehicle, \ref{['fig_AlgoPerformance_V3']} aVDS with active SSTs (V1 and V3) and \ref{['fig_AlgoPerformance_V4']} aVDS with passive SSTs (V2 and V4). The dashed white lines mark the wheel orders while the solid lines mark the engine orders introduced by the SSTs.
• Figure 3: Screenshot of the questionnaires used for subjective evaluation. \ref{['fig_MXeval_BI']} BI questionnaire for evaluating system performance and \ref{['fig_MXeval_Comp']} Comparison questionnaire for evaluating differences between the simulator variants and the reference vehicle.
• Figure 4: Absolute values of BI ratings (higher value means better). Only the value range between $4$ and $10$ is shown. The mint-colored lines and surfaces represent the simulator variants while the black lines represent the reference vehicle. SWT-ON: "SWT on-center," SWT-OFF: "SWT off-center," SWT-G: "SWT gradient," CF: "Center feel," RC: "Road contact," LF-SF: "Low-frequency Steering feedback," HF-SF: "High-frequency Steering feedback," LF-CF: "Low-frequency Chassis feedback," HF-CF: "High-frequency Chassis feedback"
• Figure 5: Estimated marginal means (EMMs) and $95\%$ confidence intervals of (a) Tire model and (b) SST status separated by User Level