Standstill Balancing of Two-Wheeled Vehicles via Steering Control

Steering-assistance systems for two-wheeled vehicles have gained attention in recent years. The intended range of application may include either low-speed or high-speed scenarios. It is well known that all two-wheeled vehicles are open-loop unstable at very low speeds. Therefore, although counter-intuitive, the stabilisation is more challenging at low speeds, rather than at high speeds, where properly designed vehicles are expected to be stable. An open research topic is the theoretical potential to balance two-wheeled vehicles at standstill and very low speeds via steering control. This work specifically addresses this scenario, with the objective of determining the recoverable region once the steering control limits are provided. Benchmark vehicle models are used in the investigation to ensure the results can be easily reproduced. The control strategy employs the divergent component of motion approach, with steering control primarily focused on stabilising the vehicle’s unstable mode. Explicit expressions for modal controllability, minimum stabilising feedback gain, and recoverable-region separatrices are derived. The investigation highlights the effect of key parameters that dominate the balancing problem and provides analytical tools and design guidelines for the development of steering-assistance systems capable of balancing two-wheeled vehicles at very low speeds and standstill.