Design and evaluation of a multi-loop control strategy applied to an anti-lock braking system

This paper presents a comparative study on the performance of a non-conventional control algorithm applied to an anti-lock braking system (ABS) of a small-size vehicle. The non-conventional controller proposed in this study corresponds to a multi-loop control strategy composed of an inner and outer loop. The outer loop is developed using a sliding mode controller (SMC) based on the maximum power point tracking (MPPT) algorithm, which calculates tire slip references to get the greatest braking force while reducing the vehicle's lateral acceleration, which prevents yaw from occurring. The inner loop consists of a controller that allows the vehicle's tires to track the previously calculated slip reference by regulating the applied pressure of the master cylinder over the wheels. Two control algorithms are tested in the inner loop: PI and fuzzy PI (F-PI). The testing scenarios are the following: i) a road with a homogeneous coefficient of friction, and; ii) a split μ road with two different friction coefficients. Simulation results showed a more significant performance in braking time, braking distance, and reduction of lateral accelerations.