Dynamic rollover-safety index-based tilt optimisation encompassing road configurations for narrow three-wheelers: Balancing energy efficiency and ride comfort

The active tilt-controlled narrow three-wheelers (3Ws) equipped with a closed cabin aim to offer a comfortable driving experience comparable to four-wheelers while maintaining the manoeuvrability of two-wheelers without compromising on speed. Based on this concept, this study explores a tilt control strategy for narrow 3Ws. While previous research has established a steady-state tilt angle considering a zero-track width, this study incorporates track width due to the multi-wheel axle configuration. This novel approach not only withstands unbalanced lateral acceleration but also saves significant tilting torque. Unnecessary tilting is minimised by introducing a tilt actuation system (TAS) based on a unique dynamic rollover index. Central to the original contribution is the stability margin (SM), a dynamic rollover-safety index considering longitudinal and lateral dynamics, surpassing the traditional rollover index load transfer ratio, particularly for delta 3Ws. This work proposes a desired SM threshold-dependent steady-state tilt angle, activating TAS only when necessary. This pioneering method optimises the desired SM threshold using goal programming. Additionally, this research addresses a critical oversight in previous studies by accounting for the influence of road slopes, ensuring consistent stability across diverse road conditions. It is crucial to note that the proposed rollover index-based tilting approach markedly outperforms the conventional methods, reinforcing its originality and potential for future vehicular design.