Abstract
This paper presents experimental evaluation of a motorcycle anti-lock brake system (ABS) using the brake pressure restriction principle. In the conventional anti-lock brake systems, the brake pressure is modulated through the slip ratio as a control variable. For motorcycle braking, however, this on-off brake pressure modulation must be done very fast to effectively avoid wheel locking because the two-wheel motorcycle dynamics is inherently unstable even with small amount of time delay in the pressure modulation process. Instead of using on-off pressure modulation system, we propose to use a pressure restriction valve that allows to pass only the pressure that is slightly lower than the wheel locking pressure. The wheel locking pressure can easily be identified and preset by a simple pressure tuning process. This simple motorcycle ABS system, therefore, does not require expensive wheel speed sensors, ECU, and a pressure modulator. Experimental field tests demonstrated that the pressure restriction principle can be applied to generate basic ABS functions with some robustness properties against uncertain load, varying road conditions and various initial braking speeds and is effective for avoiding the wheel locking.