Relationship between steering torque and ease of driving with bar type steering in high speed range

Abstract

In previous study it was confirmed that changing of grip position counteracts drivers' maintenance of appropriate steering angle. Therefore, we developed the bar type steering system with low steering gear ratio. In high-speed driving, the range of steering angles used is smaller than in low-speed driving. with a steering system with a low gear ratio, further delicate steering is required. Human operation resolving ability is insufficient for such operation, it is expected that high-speed driving at a low gear ratio will become difficult. Motorcycles enable high-speed driving even at a low gear ratio. In motorcycles, a sufficiently large torque occurs during high-speed driving. Referring to this, we developed a steering system that enables easy high-speed operation at a low gear ratio from the viewpoint of vehicle behavior including both steering angle and steering torque. As the result, the difficulty of steering operation with low steering gear ratio at high speed was improved by adjusting steering reaction torque of bar type steering. Furthermore, the dynamic characteristics from the steering torque to the vehicle was examined. As result, where a large steering torque is required, the driver drives mainly based on the steering torque. Therefore, the ease of driving does not change if the phase of steering torque is delayed from the steering angle. On the other hand, the experiment confirmed that driving becomes difficult if the yaw rate is delayed from the steering torque that the driver relies on. We designed reactive torque control system to improve maneuverability and verify performance of the system by using driving simulator. Here, we report the maneuverability of bar type steering in high speed range.