Scalable Kinematic Reconstruction Methods of Joint Angles for N-Trailer Vehicles Upon Speed Information with Application to Motion Control

On-lin. availability of instantaneous values of joint angles in (automated/intelligent) articulated vehicles is crucial for the supervision and diagnostics, localization, feedback control and motion planning purposes. Direct precise measuring of articulation angles in the joints of multi-trailer vehicles is usually expensive and mechanically challenging. In this paper, we derive, analyze, and compare two alternative (algebraic-and integral-type) on-line reconstruction methods of joint angles using only speed information of the vehicle's segments. Thanks to a modular representation of vehicle kinematics, the online reconstruction methods are highly scalable with respect to a number of trailers and applicable to N-trailer vehicles comprising an active tractor and arbitrar. number of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$N$</tex> passive trailers with fixed (non-steerable) wheels. The considered reconstruction methods require only information about the angular and longitudinal speeds of all the vehicle segments, making the joint angles reconstruction relatively inexpensive and effective in low-speed motion conditions. The methods are experimentally validated in forward and backward motion scenarios using a motion control system implemented on a board of a full-scale intralogistic (tugger-train) 3-trailer vehicle.