Improving Lateral Dynamic Stability of a-Double Vehicles at High Speeds Through a Differential Brake Control Strategy*

For better lateral dynamic stability of an A-double vehicle (comprising a tractor, semitrailer, dolly, and another semitrailer) at high speeds, it is a practical and economical way to control the dolly, a linking structure for long combination vehicles (LCVs). This paper proposes a simple differential brake control strategy based on the feedback of the yaw rate of the dolly. A stability analysis approach is employed by exploring the relationship between damping ratios and speeds, and the critical speed of an A-double vehicle is found. Next, the relationship between the A-double vehicle's damping ratios and the feedback parameter employed in this differential brake control approach is examined, showing that a more favorable feedback value can raise the vehicle's minimum damping ratio. Finally, the method of selecting feedback parameters is also provided, considering the adhesion utilization demanded by the dolly. The time-domain simulation confirms that the stability analysis utilizing the damping ratio is accurate. Using MATLAB/Simulink at various speeds, the effectiveness of this control strategy is tested under single lane-change operations. According to these simulation results, the A-double vehicle using the differential control strategy has a higher critical speed and maintains stability during single lane-change operations at high speeds. This verified that the simple differential brake control strategy has the potential to significantly increase the lateral dynamic stability of the A -double vehicle at high speeds during single-lane change operations economically and practically.