The paper 'Robust Trajectory Tracking Error Model-Based
Predictive Control for Unmanned Ground Vehicles' provide a nice algorithm, but I'm confused by the model mentioned in this paper. According to the Eq.(1) in the article, the velocity of trailer and tractor vehicle is equal, but according to the decomposition of velocity, the velocity is different, whether the details were omitted or it's an wrong equation? And why the distance between the rear axle of the tractor and RJ2 (Ld) is a constant value?
Could you explain this problem or provide a better kinematic model for Autonomous Tractor-Trailer System?