This paper discusses creating a suitable reference for the Anti-Lock Braking (ABS) control system that maximizes power recovery or dissipation of the brake system. Current anti-lock brake systems implement a finite-state method algorithm to respond to the wheel longitudinal slip by keeping the slip at the given target to maximize

braking force. Variables in the logic can include wheel-speed measured from sensors, brake target slip which is estimated by the Electronic Control Unit (ECU), reference speed, which is also estimated, and vehicle acceleration/deceleration. Angular acceleration and calculated actual wheel slip are used as indicators of the wheel’s state of motion. To find the maximum braking force, a typical ABS over-brakes such that the tire longitudinal force exceeds its maximum value and therefore, the wheel starts locking up. The ABS then adjusts by under-braking, and repeats this cycle to keep the tire longitudinal force around its maximum. This paper uses the power absorbed by the wheel to find the maximum power dissipated. Using this strategy, the ABS utilizes a continuous control strategy and can better approximate the maximum brake force without the cyclic method that has been used in the conventional ABS. In addition to maximizing the brake force as a result of this approach, driver comfort also increases due to the continuous control vs. on/off (cyclic) control during an ABS event. The paper discusses theoretical aspects of the problem, and software simulation using MATLAB and Simulink.

Current anti-lock brake systems implement a finite-state method algorithm to respond to the wheel longitudinal slip by keeping the slip at the given target to maximize braking force. Variables in the logic can include wheel-speed measured from sensors, brake target slip which is estimated by the Electronic Control Unit (ECU), reference speed, which is also estimated, and vehicle acceleration/deceleration. Angular acceleration and calculated actual wheel slip are used as indicators of the wheel’s state of motion. Current continuous control methods focus on nonlinear control techniques such as sliding mode to keep the vehicle’s slip at a desired value [1-3]. Such techniques are often not intuitive, hard to tune and require a lot of computational power to be implemented on the production vehicle.

To find the maximum braking force, a typical ABS over-brakes such that the tire longitudinal force exceeds its maximum value and therefore, the wheel starts locking up. The ABS then adjusts by under-braking, and repeats this cycle to keep the tire longitudinal force around its maximum.

In this paper, we use the one-wheel vehicle model to derive a unique control strategy for the control of a vehicle ABS, using the power absorbed by the wheel to find the maximum power dissipated. Using this strategy, the ABS utilizes continuous control and can better approximate the maximum brake force without the cyclic method that has been used in the conventional ABS. In addition to maximizing the brake force as a result of this approach, driver comfort also increases due to the continuous control vs. on/off (cyclic) control during an ABS event.

The first part of the paper consists of modeling the system. Then, using the dynamics equations of the model, we will lay the groundwork of the use of dissipated power in the context of ABS continuous control. The Simulink) and follows with the discussion of the results.

Vehicle and Brake model

Figure 1 shows a single wheel tire and all the forces, moments and velocities while braking. This simple model is chosen for the purpose of initial results on the ABS algorithm proposed in this paper. [4 9]

Power Method

The overall control architecture of new continuous ABS algorithm method is shown in Figure 4. The main idea in this architecture lies under the” Power Method” block. It provides the brake torque reference to the control loop. Additionally, a low-level controller was designed for the brake system using Youla-Kucera robust control technique [10-14].

An overall schematic of the power method reference torque generator is given in Figure 3. The inputs to the Power Method reference generator are wheel angular velocity, the brake torque, and brake torque rate of change. The wheel angular velocity can be obtained through the wheel rate sensor. However, the brake torque is not readily available with the current sensors in a commercial vehicle. Therefore, estimation techniques can be utilized to obtain the estimated brake torque. The output of the reference generator is torque reference (τref). We will discuss about (dτbdt) later in this section and also in the Mathematical Background section. Writing a simple power balance for the wheel yields to Equation 7.