Wheel lock is an undesired phenomenon in Heavy Commercial Road Vehicles (HCRVs) and wheel slip control within a desired range is of crucial importance for stable and effective braking. This study proposes a framework to distribute brake force dynamically between the front and rear wheels, primarily to avoid instability by preventing wheel lock. Further, it ensures the maximum utilization of the available traction force at the tire-road interface that varies during the course of braking due to factors like load transfer. Wheel slip regulation provides an approach to maximize braking performance that subsumes the effects of varying road, load and braking conditions that occur during vehicle deceleration. The methodology proposed consists of a wheel slip controller that calculates the required brake force distribution parameters, which are then provided to the brake controller for control action. Sliding mode control was used because of the nonlinear nature of the longitudinal vehicle dynamic model considered and for robustness towards different parameter variations. The algorithm was implemented on a Hardware-in-Loop test setup consisting of a pneumatic air brake system, interfaced with IPG-TruckMaker® (a vehicle dynamic simulation software), and co-simulated with MATLAB-Simulink®. It was found that this algorithm improved the braking performance of a HCRV both in terms of stopping distance and vehicle stability.

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