Bicycle balance assist system reduces roll motion for young and old bicyclists during real-life safety challenges

Abstract

Bicycles are more difficult to control at low speeds due to the vehicle’s unstable low-speed dynamics. Factors such as aging, disturbances, and multitasking can make it even more difficult to control.

Together with Royal Dutch Gazelle and Bosch eBike Systems we developed a second prototype ‘balance assist system’ at Delft University of Technology and implemented the ‘steer-into-the-fall’ control algorithm to produce the assistive steering torque. We evaluated the effectiveness of the balance assist at low forward speed on 18 old and 14 young cyclists in some conditions that might affect cycling safety, including handlebar disturbances, multi-tasking, and aging. Participants totally performed 16 trials (2 Scenarios (single- and multi-task) x 2 Balance assist states (on/off) x 2 Disturbances states (on/off) x 2 repetitions). In multi-task scenario, in addition to cycling on a straight line, participants performed a shoulder-check task and followed instruction corresponding to the identified visual cues. In half of the trials in both scenarios we implemented the disturbances through the steer motor. We calculated the bicycle mean magnitude of roll and steering rate – as indicators of bicycle balance control and steering effort, respectively – and the rider’s mean magnitude of lean rate to investigate the effect of the balance assist system on these variables.

Balance assist system decreased the bicycle’s roll rate in all conditions. The decrease in roll rate was more pronounced in older adults during the single-task in both disturbed and undisturbed conditions. Balance assist decreased the steering rate, only in single-task cycling in both age groups, indicating less steering effort is required to maintain balance. The rider’s lean rate with respect to the ground was not significantly affected by age, disturbances, or the balance assist. This could be caused by the minimum role the upper body plays when riders have good steering control authority. Overall, lateral motion and steering rate can be affected by age, disturbances, and multitasking, and the balance assist system shows that potential to improve cycling safety and reduce the number of single-actor crashes. More investigation on riders’ contribution to control actions is required.