28,825 research outputs found
A path planning and path-following control framework for a general 2-trailer with a car-like tractor
Maneuvering a general 2-trailer with a car-like tractor in backward motion is
a task that requires significant skill to master and is unarguably one of the
most complicated tasks a truck driver has to perform. This paper presents a
path planning and path-following control solution that can be used to
automatically plan and execute difficult parking and obstacle avoidance
maneuvers by combining backward and forward motion. A lattice-based path
planning framework is developed in order to generate kinematically feasible and
collision-free paths and a path-following controller is designed to stabilize
the lateral and angular path-following error states during path execution. To
estimate the vehicle state needed for control, a nonlinear observer is
developed which only utilizes information from sensors that are mounted on the
car-like tractor, making the system independent of additional trailer sensors.
The proposed path planning and path-following control framework is implemented
on a full-scale test vehicle and results from simulations and real-world
experiments are presented.Comment: Preprin
Path-tracking of a tractor-trailer vehicle along rectilinear and circular paths: A Lyapunov-based approach
Published versio
Optimization of vehicle-trailer connection systems
The three main requirements of a vehicle-trailer connection system are: en route
stability, over- or under-steering restraint, minimum off-tracking along curved path. Linking
the two units by four-bar trapeziums, wider stability margins may be attained in comparison
with the conventional pintle-hitch for both instability types, divergent or oscillating. The
stability maps are traced applying the Hurwitz method or the direct analysis of the
characteristic equation at the instability threshold. Several types of four-bar linkages may be
quickly tested, with the drawbars converging towards the trailer or the towing unit. The latter
configuration appears preferable in terms of self-stability and may yield high critical speeds by
optimising the geometrical and physical properties. Nevertheless, the system stability may be
improved in general by additional vibration dampers in parallel with the connection linkage.
Moreover, the four-bar connection may produce significant corrections of the under-steering or
over-steering behaviour of the vehicle-train after a steering command from the driver. The offtracking
along the curved paths may be also optimized or kept inside prefixed margins of
acceptableness. Activating electronic stability systems if necessary, fair results are obtainable
for both the steering conduct and the off-tracking
A Discrete Geometric Optimal Control Framework for Systems with Symmetries
This paper studies the optimal motion control of
mechanical systems through a discrete geometric approach. At
the core of our formulation is a discrete Lagrange-d’Alembert-
Pontryagin variational principle, from which are derived discrete
equations of motion that serve as constraints in our optimization
framework. We apply this discrete mechanical approach to
holonomic systems with symmetries and, as a result, geometric
structure and motion invariants are preserved. We illustrate our
method by computing optimal trajectories for a simple model of
an air vehicle flying through a digital terrain elevation map, and
point out some of the numerical benefits that ensue
Anti-Jackknifing Control of Tractor-Trailer Vehicles via Intrinsically Stable MPC
It is common knowledge that tractor-trailer vehicles are affected by jackknifing, a phenomenon that consists in the divergence of the trailer hitch angle and ultimately causes the vehicle to fold up. For the case of backwards motion, in which jackknifing can also occur at low speeds, we present a control method that drives the vehicle along a reference Cartesian trajectory while avoiding the divergence of the hitch angle. In particular, a feedback control law is obtained by combining two actions: a tracking term, computed using input-output linearization, and a corrective term, generated via IS-MPC, an intrinsically stable MPC scheme which is effective for stable inversion of nonminimum-phase systems. The proposed method has been verified in simulation and experimentally validated on a purposely built prototype
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