Robust static output feedback synthesis for platoons under leader and predecessor feedback

Artikel i vetenskaplig tidskrift, 2017

A multi-objective static output feedback synthesis problem is considered for the control of vehicle platoons under leader and predecessor feedback. Sufficient linear matrix inequality conditions are derived for the solvability of the problem in a way to facilitate static feed-forward as well. A novel velocity-dependent spacing policy is integrated into the control scheme together with a platoon model in which the emphasis on the predecessor information can be adjusted by a normalized scalar weight. It is shown that the string stability of the spacing errors and the acceleration signals can always be guaranteed by choosing this weight sufficiently small. Moreover, provided that the time headway is chosen sufficiently large, the synthesis can be performed in a way to avoid the amplification of acceleration energies if compared with the leader. As a particularly convenient feature, the target spacing between the vehicles becomes smaller when moving backward along the platoon. The total increase in the platoon length caused by the introduction of the velocity-dependent scheme is shown to be bounded and decreasing with decreasing predecessor weight. It is also established that the predecessor weight can be adjusted smoothly over time without endangering the formation stability. In addition to the optimization of the parameters of common fixed-structure controllers for general vehicle models, the proposed synthesis procedure provides various tools for improving robustness against measurement noise, communication delay, and model uncertainty.