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Modelling commercial vehicle handling and rolling stability
YesThis paper presents a multi-degrees-of-freedom non-linear multibody dynamic
model of a three-axle heavy commercial vehicle tractor unit, comprising a subchassis, front
and rear leaf spring suspensions, steering system, and ten wheels/tyres, with a semi-trailer
comprising two axles and eight wheels/tyres. The investigation is mainly concerned with the
rollover stability of the articulated vehicle. The models incorporate all sources of compliance,
stiffness, and damping, all with non-linear characteristics, and are constructed and simulated
using automatic dynamic analysis of mechanical systems formulation. A constant radius turn
test and a single lane change test (according to the ISO Standard) are simulated. The constant
radius turn test shows the understeer behaviour of the vehicle, and the single lane change
manoeuvre was conducted to show the transient behaviour of the vehicle. Non-stable roll
and yaw behaviour of the vehicle is predicted at test speeds .90 km/h. Rollover stability of
the vehicle is also investigated using a constant radius turn test with increasing speed.
The articulated laden vehicle model predicted increased understeer behaviour, due to higher
load acting on the wheels of the middle and rear axles of the tractor and the influence of the
semi-trailer, as shown by the reduced yaw rate and the steering angle variation during the constant
radius turn. The rollover test predicted a critical lateral acceleration value where complete
rollover occurs. Unstable behaviour of the articulated vehicle is also predicted in the single lane
change manoeuvre
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
Fractional Order State Feedback Control for Improved Lateral Stability of Semi-Autonomous Commercial Heavy Vehicles
With the growing development of autonomous and semi-autonomous large commercial heavy vehicles, the lateral stability control of articulated vehicles have caught the attention of researchers recently. Active vehicle front steering (AFS) can enhance the handling performance and stability of articulated vehicles for an emergency highway maneuver scenario. However, with large vehicles such tractor-trailers, the system becomes more complex to control and there is an increased occurrence of instabilities. This research investigates a new control scheme based on fractional calculus as a technique that ensures lateral stability of articulated large heavy vehicles during evasive highway maneuvering scenarios. The control method is first implemented to a passenger vehicle model with 2-axles based on the well-known “bicycle model”. The model is then extended and applied onto larger three-axle commercial heavy vehicles in platooning operations. To validate the proposed new control algorithm, the system is linearized and a fractional order PI state feedback control is developed based on the linearized model. Then using Matlab/Simulink, the developed fractional-order linear controller is implemented onto the non-linear tractor-trailer dynamic model. The tractor-trailer system is modeled based on the conventional integer-order techniques and then a non-integer linear controller is developed to control the system. Overall, results confirm that the proposed controller improves the lateral stability of a tractor-trailer response time by 20% as compared to a professional truck driver during an evasive highway maneuvering scenario. In addition, the effects of variable truck cargo loading and longitudinal speed are evaluated to confirm the robustness of the new control method under a variety of potential operating conditions
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