Search

Driving articulated heavy vehicles (AHVs) at high-speeds is complicated due to their unstable motion modes. Accelerated motion trajectory planning is essential for collision avoidance (CA) maneuver in dynamic traffic conditions. This article proposes a new trajectory planning strategy for collision-free and feasible maneuver of a tractor semi-trailer truck in critical conditions in which the truck and the obstacles are moving with non-constant speeds. For this purpose, a convenient optimal practical trajectory for different tire-road frictional conditions, the physical limitation of the tires, and the stability status of the truck is suggested. The main strategy of the trajectory planning is to increase the capability of the control system using the longitudinal and lateral forces of the tires. A robust integrated controller is then proposed to control the longitudinal and lateral directions of the AHV of which the longitudinal controller is configured to track the longitudinal position considering the vehicle stability conditions, and the lateral controller is organized to follow the yaw rate, the lateral position of the tractor, and the articulation angle. The results show that the proposed novel strategy with integrated longitudinal and lateral control has convenient performance in high-speed and low friction conditions as well as normal situations. [ABSTRACT FROM AUTHOR]

In this article, a decentralized strategy is applied for active control of sound inside the automobile cabin by considering the uncertainty caused by the movement of the occupants. A coupled structural-acoustic analysis is done on the simplified geometry of the automobile cabin with passengers by the finite element method. The uncertainty caused by changes in the occupants' head positions and angles is also considered. Then, a decentralized robust feedback control strategy is proposed to reduce the sound pressure level in the ears of all the occupants using the H∞ method for each individual control unit by considering the unstructured uncertainty of the plant. The efficiency of the proposed control strategy in minimizing the sound pressure level caused by the structural disturbance on the firewall panel is investigated. [ABSTRACT FROM AUTHOR]

This study designs an adaptive integrated control. The control system includes two strategies of individual optimal linear quadratic regulator: one to improve vehicle maneuverability and another to improve vehicle stability. The integration is based on the vehicle dynamic variables in the phase plane. The controller can adapt itself by changing gains and integration law as vehicle mass and road friction change. The proper gains and integration law are determined for four special conditions: dry road-curb weight, dry road-gross weight, wet road-curb weight, and wet road-gross weight. These conditions are then expanded for every value of vehicle mass and road friction through fuzzy logic and Sugeno estimator. Simulation results show that considerable improvements are achieved in vehicle dynamic performance through the adaptive integrated control system. [ABSTRACT FROM AUTHOR]

This study proposes a drowsiness detection approach based on the combination of several different detection methods, with robustness to the input signal loss. Hence, if one of the methods fails for any reason, the whole system continues to work properly. To choose correct combination of the available methods and to utilize the benefits of methods of different categories, an image processing-based technique as well as a method based on driver-vehicle interaction is used. In order to avoid driving distraction, any use of an intrusive method is prevented. A driving simulator is used to gather real data and then artificial neural networks are used in the structure of the designed system. Several tests were conducted on twelve volunteers while their sleeping situations during one day prior to the tests, were fully under control. Although the impact of the proposed system on the improvement of the detection accuracy is not remarkable, the results indicate the main advantages of the system are the reliability of the detections and robustness to the loss of the input signals. The high reliability of the drowsiness detection systems plays an important role to reduce drowsiness related road accidents and their associated costs. [ABSTRACT FROM AUTHOR]

In a mechatronical approach, the design of a highly detailed, physically based model of a semi-automatic powertrain suitable for supervision has been explicated. In each part of the powertrain system, ultimately developed dynamical models have been exploited to make sure the whole model is up-to-date and is close to a real system. Advanced dynamical equations of an engine, a clutch, a gearbox and a driveline as well as a tire and a vehicle dynamic model for analyzing longitudinal performance have been considered. A well-suited automated manual transmission (AMT) along with a mean value transient spark-ignition (SI) engine model has been inserted to complete the solution. In order to simulate a real vehicle, the nonlinearities of the powertrain system mainly generated in the engine and clutch have drawn attention. Transient behavior of the system is a key parameter for design; hence, both steady-state and transient modeling such as of the gear shift procedure were considered. All parts of the model have been verified against experimental data. Finally, an overall simulation of the powertrain and vehicle in an in-city Economic Commission for Europe (ECE) cycle and a complete involved simulation of a gear shift process using Simulink have been performed to examine the level of the modeled dynamics. Lastly, it will be clear that use of nonlinear and real-world models can enhance the modeling and make it comparable to a real system. [ABSTRACT FROM AUTHOR]

Directional response and roll stability characteristics of a partly filled tractor semi-trailer vehicle, with cylindrical tank, under different parameters and conditions are investigated. The effective parameters and conditions in the stability of a tractor semi-trailer carrying liquid can be considered as filled volume, kinematic viscosity of liquid cargo and vehicle steering input. The dynamic interaction of liquid cargo with the tractor semi-trailer vehicle is evaluated by integrating a dynamic slosh model of the partly filled tank with five-degrees-offreedom of a tractor semi-trailer tank model. The dynamic fluid slosh within the tank is modeled using three-dimensional Navier-Stokes equations, coupled with the volume-of-fluid equations and analyzed using FLUENT software. The coupled tank-vehicle model is subsequently analyzed to determine the roll stability characteristics for different conditions and maneuvers. The results show effects of parameter variations on roll stability of the vehicle carrying liquid and also fluid's behavior in interaction with a vehicle's dynamics. [ABSTRACT FROM AUTHOR]

Road roughness is a broad term that incorporates everything from potholes and cracks to the random deviations that exist in a profile. To build a roughness index, road irregularities need to be measured first. Existing methods of gauging the roughness are based either on visual inspections or using one of a limited number of instrumented vehicles that can take physical measurements of the road irregularities. This paper more specifically focuses on the estimation of a road profile (i.e., along the 'wheel track'). This paper proposes a solution to the road profile estimation using a wavelet neural network (WNN) approach. The method incorporates a WNN which is trained using the data obtained from a 7-DOF vehicle dynamic model in the MATLAB Simulink software to approximate road profiles via the accelerations picked up from the vehicle. In this paper, a novel WNN, multi-input and multi-output feed forward wavelet neural network is constructed. In the hidden layer, wavelet basis functions are used as activate function instead of the sigmoid function of feed forward network. The training formulas based on BP algorithm are mathematically derived and a training algorithm is presented. The study investigates the estimation capability of wavelet neural networks through comparison between some estimated and real road profiles in the form of actual road roughness. [ABSTRACT FROM AUTHOR]

Modern software tools have enhanced modelling, analysis and simulation capabilities pertaining to control of dynamic systems. In this regard, in this paper a full vehicle model with flexible body is exposed by using MSC. ADAMS and MSC. NASTRAN. Indeed, one of the most significant vehicle dynamic controls is directional stability control. In this case, the vehicle dynamic control system (VDC) is used to improving the vehicle lateral and yaw motions in critical manoeuvres. In this paper, for design the VDC system, an optimal control strategy has been used for tracking the intended path with optimal energy. For better performance of VDC system, an anti-lock brake system (ABS) is designed as a lower layer of the control system for maintaining the tyre longitudinal slip in proper value. The performances of the controller on rigid and flexible models are illustrated, and the results show the differences between the control efforts for these models, which are related to the differences of dynamic behaviours of rigid and flexible vehicle dynamic models. [ABSTRACT FROM AUTHOR]

This paper presents a method based on continuous wavelet transform to detect the faults of vehicle suspension systems. The Morlet wavelet functions are employed to approach the natural frequencies of the system and the frequency components of the signal with relative maximum energy. To evaluate our method, we use a full vehicle dynamic model which has been simulated in ADAMS/CAR and validated by laboratory test results. The suspension faults have been considered due to the damage of shock absorbers (dampers) and upper damper bushings (UDBs) and assumed as the decrease in damping force and loose joints, respectively. In this paper, the incapability of the spectral analysis by using fast Fourier transform in analysis of the signals is revealed through applying the inputs that include transient characteristics and then wavelet transform employed to achieve more proper results. A swept frequency is applied as an input to the wheels that simulates the road irregularities. After detection of faulty sections of the system using signal energy distribution, the defects of damper and UDBs are distinguished from each other through observing the changes of natural frequencies and corresponding energy amplitudes. [ABSTRACT FROM AUTHOR]

The problem of controlling a string of vehicles moving in one dimension is considered so that they all follow a lead vehicle with constant time headway spacing between successive vehicles. Due to realistic design and execution, the negative effect of the tracking lag parameter and time delay is taken into account. By applying an acceleration feedforward, the distance error of each vehicle will be independent of the behavior of other vehicles. As a result, the vehicle is better able to track a desired trajectory, which improves the string stability. Cluster treatment of characteristic roots (CTCR) paradigm is utilized to reveal the stabilizing parametric regions in the domain of the time delay to render the stability of closed loop system. The string stability analysis is performed to evaluate the disturbance attenuation. Finally, an example of multiple vehicle platoon control is presented, which demonstrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The problem of controlling a string of vehicles moving in one dimension is considered so that they all follow a lead vehicle with constant spacing between successive vehicles. Due to practical design and implementation, the negative effect of the tracking lag parameter is taken into account. A hierarchical platoon controller design framework is established comprising a feedback linearization controller at the first layer and a decentralized bidirectional control controller at the second layer. The stability criterion is examined by using a partial differential equation approximation in the limit of the number of vehicles subjected to unequal asymmetry in position and velocity feedback. For disturbance attenuation, string stability analysis is also examined. At the end of the paper, simulations are given to show the efficiency of the proposed results. [ABSTRACT FROM PUBLISHER]