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J Intell Robot Syst (2014) 75:2952
DOI 10.1007/s10846-013-9846-2
Lining-Up Control Strategies for N-trailer Vehicles
Maciej Marcin Michaek
Received: 28 January 2013 / Accepted: 20 May 2013 Springer Science+Business Media Dordrecht 2013
Abstract Maneuvers performed with tractor-trailers vehicles (N-trailers) belong to the most demanding motion control tasks in the transportation practice. Very frequent maneuvers concern the lining-up process of a vehicle chain, usually as a preliminary stage which prepares the system to subsequent parking/docking maneuvers. The most common lining-up control approach results from utilization of the open-loop asymptotic stability of N-trailer joint-angle dynamics in the forward motion. However, in case of long trailers this approach appears very inefficient especially if the available motion space is substantially limited. By using the triangular forms of joint-angle dynamics the problem of lining-up control for N-trailers is analyzed in the paper by considering two alternative strategies: active lining-up (feedback control) and passive lining-up (open-loop control). The two strategies are compared in the context of their practical effectiveness, and how the effectiveness depends on kinematic parameters of the trailers
/ Published online: Ju 2013
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and their interconnections. It is revealed why the active strategy can be much more efficient in most practical cases. Theoretical considerations are validated by results of numerical simulations and experiments conducted with a laboratory-scale three-trailer robotic vehicle.
Keywords N-trailer vehicles Off-axle hitching
On-axle hitching Feedback control
Open-loop control Triangular forms
1 Introduction
N-trailers are the most popular articulated vehicles of the ground transportation. They consist of an active tractor equipped with passive trailers [22] connected in series through one of possible hitching types: on-axle or off-axle. N-trailers possess highly nonlinear kinematics with several specific properties (like nonholonomy and underactuation, structural in-joint-instability during backward motion, and non-minimum-phase property of joint-angle dynamics [17]) which make them especially unintuitive and difficult systems to manual control. N-trailer vehicles can be divided into three categories: standard N-trailers (SNT, see [9, 10]) where all the trailers are hitched exactly at a mid-point of a preceding wheels axle (on-axle hitching), non-standard N-trailers (nSNT, cf. [16]) where all the trailers are hitched
This work was supported by the statutory grant No. 93/194/13 DS-MK.
M. M. Michaek (B)
Chair of Control and Systems Engineering, Poznan University of Technology (PUT), Piotrowo 3A, 60-965 Poznan, Poland...