5.4. ACTIVE BRAKING SYSTEM 55
Vehicle Dynamics Control
Information Driver Input
Force and Moment of Vehicle
Lateral and Longitudinal Forces of Tires
Driving Torque, Brake Pressure, Steer Angle
Force and Moment Distribution
Wheel Control
Actuator
(Result)
(Target)
Figure 5.5: Hierarchical vehicle dynamics management algorithm.
Vehicle Dynamics Control: this layer calculates the target force and moment of the vehicle
to achieve a desirable vehicle motion corresponding to the driver’s pedal input and steering
wheel angle. e determined target resultant force and moment also satisfy the robust stability
condition.
Force and Moment Distribution: the target resultant force and moment of the vehicle
motion are distributed to target tire forces of each wheel based on the friction circle of each
wheel in this layer.
Wheel Control: this layer controls each wheel motion to achieve the target tire force.
5.4 ACTIVE BRAKING SYSTEM
Differential braking system applies unequal braking force to the different wheels, which gener-
ates a corresponding additional yawing moment to change the yaw rate of the vehicle. On the
other hand, it can also decrease the vehicle speed, thus the anti-rollover property of vehicle is
improved. Some researchers used differential braking to keep the value of LTR below a certain
level and yield robustness to variations in vehicle speed [29, 55]. More control effort would be
exerted for drivers with poor driving skills, and vice versa. Zhu proposed a sliding mode con-
trol (SMC)-based differential braking controller which based on a novel driver-adaptive Vehicle
Stability Control (DAVSC) strategy [20].
Figure 5.6 shows the yaw moment change when the braking force is applied at front-inner
wheel, rear-inner wheel, front-outer wheel, and rear-outer wheel, respectively. It is observed that
applying the braking force to the front-outer wheel or rear-inner wheel can better prevent the
vehicle from yaw motion, thus improving the roll stability of the vehicle.