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Showing 4 results for Vehicle Dynamics

S.m. Shariatmadar, M. Manteghi, M. Tajdari,
Volume 2, Issue 2 (4-2012)
Abstract

Non-linear characteristic of tire forces is the main cause of vehicle lateral dynamics instability, while direct yaw moment control is an effective method to recover the vehicle stability. In this paper, an optimal linear quadratic regulator (LQR) controller for roll-yaw dynamics to articulated heavy vehicles is developed. For this purpose, the equations of motion obtained by the MATLAB software are coded and then a control law is introduced by minimizing the local differences between the predicted and the desired responses. The influence of some parameters such as the anti roll bar, change the parameters of the suspension system and track wide in articulated heavy vehicles stability has been studied. The simulation results show that the vehicle stability can be remarkably improved when the optimal linear controller is applied
M. A. Saeedi, R. Kazemi,
Volume 3, Issue 1 (3-2013)
Abstract

In this study, stability control of a three-wheeled vehicle with two wheels on the front axle, a three-wheeled vehicle with two wheels on the rear axle, and a standard four-wheeled vehicle are compared. For vehicle dynamics control systems, the direct yaw moment control is considered as a suitable way of controlling the lateral motion of a vehicle during a severe driving maneuver. In accordance to the present available technology, the performance of vehicle dynamics control actuation systems is based on the individual control of each wheel braking force known as the differential braking. Also, in order to design the vehicle dynamics control system the linear optimal control theory is used. Then, to investigate the effectiveness of the proposed linear optimal control system, computer simulations are carried out by using nonlinear twelvedegree- of-freedom models for three-wheeled cars and a fourteen-degree-of-freedom model for a fourwheeled car. Simulation results of lane change and J-turn maneuvers are shown with and without control system. It is shown that for lateral stability, the three wheeled vehicle with single front wheel is more stable than the four wheeled vehicle, which is in turn more stable than the three wheeled vehicle with single rear wheel. Considering turning radius which is a kinematic property shows that the front single three-wheeled car is more under steer than the other cars.
A. Jafari, Sh. Azadi, M. Samadian,
Volume 3, Issue 3 (9-2013)
Abstract

The directional response and roll stability characteristics of a partly filled tractor semi-trailer vehicle, with cylindrical tank, are investigated in various maneuvers. The dynamic interaction of liquid cargo with the tractor semi-trailer vehicle is also evaluated by integrating a dynamic slosh model of the partly filled tank with five-degrees-of-freedom of a tractor semi-trailer tank model. The dynamic fluid slosh within the tank is modeled using three-dimensional Navier-Stokes equations, coupled with volume-of-fluid equations and analysed using the FLUENT software. The coupled tank-vehicle model is subsequently analysed to determine the roll stability characteristics for different maneuvers. The results showed the interaction of fluid slosh with vehicle's dynamic. Another findings of this investigation also revealed that the roll stability of a tractor semi-trailer tank carrying liquid was highly affected by fluid sloshing and caused degradation of roll stability in comparison with vehicle carrying rigid cargo.
S. A. Milani, S. Azadi,
Volume 4, Issue 4 (12-2014)
Abstract

Nowadays, the use of small vehicles is spreading among urban areas and one sort of these vehicles are three-wheeled vehicles (TWVs) which can be competitive with four-wheeled urban vehicles (FWVs) in aspects such as smallness, simple manufacturing, and low tire rolling resistance, fuel consumption and so on. The most critical instability associated with TWVs is the roll over. In this paper a tilt control mechanism has been modeled which can reduce the danger of roll over by leaning the vehicle towards the turning center in order to decrease the amount of lateral load transfer (LLT), and by doing so, system combines the dynamical abilities of a passenger car with a motorcycle. A 3 degree of freedom vehicle model is simulated at constant speed in MATLAB-Simulink environment and a fuzzy algorithm is developed to control such a non-linear system with appropriate tilting torque. Results are interpreted in presence and absence of controller with different longitudinal speeds and steering inputs the results are also compared to behavior of a similar FWV and this is concluded that the tilt control system could countervail deficiencies of the TWV compared to the FWV.

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