Assessing the Impact of a Cooperative Merging System on Highway Traffic Using a Microscopic Flow Simulator

Vehicle merging on highways has always been an important aspect, which directly affects the capacity of the highway. Under critical traffic conditions, the merging of main road traffic and on-ramp traffic is known to trigger speed breakdown and congestion. Additionally, merging is one of the most stressful tasks for the driver, since it requires a synchronized set of observations and actions. Consequently, drivers often perform merging maneuvers with low efficiency. Emerging vehicle technologies, such as cooperative adaptive cruise control and/or merging-assistance systems, are expected to enable the so-called “cooperative merging”. The purpose of this work is to propose a cooperative merging system and evaluate its performance and its impact on highway capacity. The modeling and simulation of the proposed methodology is performed within the framework of a microscopic traffic simulator. The proposed model allows for the vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communication, which enables the effective handling of the available gaps between vehicles. Different cases are examined through simulations, in order to assess the impact of the system on traffic flow, under various traffic conditions. Useful conclusions are derived from the simulation results, which can form the basis for more complex merging algorithms and/or strategies that adapt to traffic conditions.

Aerodynamic Simulation of Evacuated Tube Transport Trains With Suction at Tail

Steady Navier-Stokes (N-S) equations for two dimensional flow using standard k-ε turbulence modeling was solved with the help of FLUENT 14 software to simulate the flow around a train in an evacuated tunnel. Suction mechanism at the rear end was applied to study the additional reduction effect of the aerodynamic drag on the vehicle. It was observed that coefficient of drag was decreasing with the increase of suction speed. Similar investigations have also been performed by taking different shapes of the head and tail of the vehicle at the same blockage ratio under different pressures of evacuation. It was found that with the decrease of ambient pressure the aerodynamic drag reduced for any geometrical shape. Investigations have also been performed on the wake structure with respect to wake size.

Mobility and Energy Efficiency of Military Tactical Vehicle With Hybrid-Electric Driveline System

In this paper, a technical concept is described for a power transmitting unit to control the split of power between the drive axles of a 4×4 hybrid-electric vehicle. This new power transmitting unit uses a planetary gear set and eddy current brake to provide a continuously variable gear ratio that can be integrated into the vehicle driveline between the transfer case and front axle. The paper details the electrical and mechanical characteristics of the device, including its operation mode, its mathematical model built from the equations of the planetary gear set and eddy current brake, the optimization equation by which the device will be controlled to improve vehicle slip efficiency, as well as its torque and electrical current usage. Computer simulations are performed on a mathematical model of a 4×4 military truck using the power transmitting unit in conjunction with a series hybrid-electric configuration transmission.

Vehicle Handling Dynamics Optimization Based in Passive Suspension Settings in Target Cascading Framework

The vehicle optimal design is a multi-objective multi-domain optimization problem. Each design aspect must be analyzed by taking into account the interactions present with other design aspects. Given the size and complexity of the problem, the application of global optimization methodologies is not suitable; hierarchical problem decomposition is beneficial for the problem analysis. This paper studies the handling dynamics optimization problem as a sub-problem of the vehicle optimal design. This sub-problem is an important part of the overall vehicle design decomposition. It is proposed that the embodiment design stage can be performed in an optimal viewpoint with the application of the analytical target cascading (ATC) optimization strategy. It is also proposed that the design variables should have sufficient physical significance, but also give the overall design enough design degrees of freedom. In this way, other optimization sub-problems can be managed with a reduced variable redundancy and sub-problem couplings. Given that the ATC strategy is an objective-driven methodology, it is proposed that the objectives of the handling dynamics, which is a sub-problem in the general ATC problem, can be defined from a Pareto optimal set at a higher optimization level. This optimal generation of objectives would lead to an optimal solution as seen at the upper-level hierarchy. The use of a lumped mass handling dynamics model is proposed in order to manage an efficient optimization process based in handling dynamics simulations. This model contains detailed information of the tire properties modeled by the Pacejka tire model, as well as linear characteristics of the suspension system. The performance of this model is verified with a complete multi-body simulation program such as ADAMS/car. The handling optimization problem is presented including the proposed design variables, the handling dynamics simulation model and a case study in which a double wishbone suspension system of an off-road vehicle is analyzed. In the case study, the handling optimization problem is solved by taking into account couplings with the suspension kinematics optimization problem. The solution of this coupled problem leads to the partial geometry definition of the suspension system mechanism.

Prediction of Contact Area and Frictional Behaviour of Rubber on Rigid Rough Surfaces

In the tire-road contact friction depends on several influencing variables (e.g. surface texture, real contact area, sliding velocity, normal contact pressure, temperature, tread block geometry, compound and on the existence of a lubrication film). A multi-scale model for prediction of contact area and frictional behaviour of rubber on rigid rough surfaces at different length scales is presented. Within this publication the multi-scale approach is checked regarding convergence. By means of the model influencing parameters like sliding velocity, compound and surface texture on friction and contact area will be investigated.

Study and Development of Vehicle Collision Detection System

In order to reduce the alarmingly increasing vehicle accident worldwide, developing collision detection system has been an endeavor of engineers within the last 3–4 decades. Based on the vehicles’ speed and acceleration, detecting the safe distance is one of the approaches reported in research results and claimed patents. As speed and acceleration of both the involved vehicles is changing with time, developing effective algorithms that can capture and process sufficient dynamic information and then warn for or take appropriate action is demanded. One possible approach that can contribute to the effort of minimizing vehicle collision accidents is to use embedded electronic systems to control the speed of the vehicle(s). Accordingly, the study and research work reported in this article focuses on developing a model of rear-end anti-collision system that can detect the distance between two vehicles moving on the same lane in the same direction and alert the driver whenever danger is eminent within certain tolerance range.

Performance Investigation of an Eight Cylinder Gasoline Engine

Performance investigation of a Chevrolet 5.7, eight cylinder gasoline engine is experimentally carried out at laboratuary conditions by means of the special softwares called “NetDyn” and “WinDyn”. This experimental work is intended to make contribution to the researchers that experimentally analyze the parameters of gasoline engines with the engine speed in detail. During the experiments, the engine speed is changed from 2500 rpm to 5250 rpm with 250 rpm intervals and steptime for succesive speeds is kept constant as 10 s. Engine power, engine torque, fuel and air flowrates per kW, mechanical efficiency, oil temperature and pressure, break mean effective pressure and exhaust temperatures are measured as a function of engine speed. As the engine speed was increased, it was observed that the air mass flow rate, exhaust and oil temperatures increased while the break mean effective pressure, mechanical volumetric efficiency, and engine torque decreased. Engine power increased between the engine speeds of 2500 rpm and 3750, but it decreased between the speeds of 3750 rpm 5246 rpm.

Design of SUV Differential Braking Controller Considering the Interactions of Driver and Control System

This paper presents the design and validation of a differential braking controller for sport utility vehicles (SUVs) using driver-in-the-loop real-time simulations. SUVs are constructed with high ground clearance, which is the main reason for their high rollover rate. A nonlinear 3 degrees-of-freedom (DOF) SUV model with the Dugoff’s tire model is generated to design a differential braking controller. The desired states will be decided using a 2-DOF bicycle model and the automated lane-keeping control results derived from the vehicle velocity and the curvature of the road to negotiate. Actual vehicle states, observed from the nonlinear model, may deviate from the desired ones. A nonlinear robust controller, namely sliding model controller (SMC), is designed to minimize the state error so as to improve the performance measures, e.g., yaw stability. The proposed controller constructed in Labview software is integrated with a virtual SUV developed in CarSim package for co-simulations. The effectiveness of the controller is first investigated using the emulated sine-with-dwell maneuver specified in FMVSS 126. The overall SUV performance depends not only on the control scheme, but on its interaction with the human driver. To investigate the interaction of the driver and the controller, the dynamics of the overall system is simulated using driver-software-in-the-loop real-time simulations (DSIL) under a double-line-change (DLC) maneuver emulated on the DSIL platform in the Multidisciplinary Vehicle Systems Design Laboratory (MVSDL) at the University of Ontario Institute of Technology (UOIT). The simulations show that, even equipped with the electronic stability control (ESC) system, the driver still plays an important role in the vehicle dynamics. The simulations demonstrate the effectiveness of the proposed differential braking controller for enhancing the lateral stability of the SUV. Furthermore, the research discloses important interactions of the driver and the ESC system, and a driver’s training program is highly recommended.

Improving Child Safety Seat Performance Through Finite Element Simulations

In this study, a finite element (FE) model of a child seat was developed. This model along with a HIII 6-year-old child ATD model was validated against four sled tests with different restraint conditions under FMVSS 213 test environments. The simulated results of ATD kinematics and restraint forces correlated well to the test data. In order to reduce the weight of the child seat while keeping its safety performance, different design concepts were explored by FE simulations with a mesh morphing method. It was found that lowering the height of child seat base can effectively reduce the weight and head/knee excursions in frontal crashes at the same time. Reducing the material in low stress areas would reduce the weight but slightly increase the ATD head and knee excursions in crashes. Overall, the modified design with reduced based height and reduced weight in low stress areas has a weight of 1.13 lbs less than the original seat, and the ATD head and knee excursions in FMVSS 213 test conditions with four different restraint conditions all reduced. In addition, it was found that changing the tube shape can potentially change the distribution of the head and knee excursions without much impact on weight. This study demonstrated the feasibility and usefulness for introducing FE simulations into the child seat design process. Future studies using this validated FE child seat model should focus on other crash scenarios, such as those with different impact severities and directions to improve safety performance of the child seat design.

Sensitivity Analysis of Vehicle Parameters for Heading Angle Control of an Unmanned Ground Vehicle

Even if there are many software and mathematical models available in the literature to analyze the dynamic performance of Unmanned Ground Vehicles (UGVs), it is always difficult to identify or collect the required vehicle parameters from the vehicle manufacturer for simulation. In analyzing the vehicle handling performance, a difficult and complex task is to use an appropriate tire model that can accurately characterize the ground-wheel interaction. Though, the well-known ‘Magic Formula’ is widely used for this purpose, it requires expensive test equipment to estimate the Magic Formula coefficients. The design of longitudinal and lateral controllers plays a significant role in path tracking of an UGV. Though the speed of the vehicle may remain almost constant in most of the maneuvers such as lane change, Double Lane Change (DLC), step steer, cornering, etc., design of the lateral controller is always a challenging task as it depends on the vehicle parameters, road information and also on the steering actuator dynamics. Although a mathematical model is an abstraction of the actual system, the controller is designed based on this model and then deployed on the real system. In this paper, a realistic mathematical model of the vehicle considering the steering actuator dynamics has been developed by calculating the cornering stiffnesses from the basic tire information and the vertical load on each tire. A heading angle controller of the UGV has been considered using the Point-to-Point navigation algorithm. Then, these controllers have been implemented on a test platform equipped with an Inertial Measurement Unit (IMU) and a Global Positioning System (GPS). A wide range of experiments such as J-Turn, lane change and DLC have also been conducted for comparison with the simulation results. Sensitivity analysis has been carried out to check the robustness and stability of the controller by varying the cornering stiffness of tires, the most uncertain parameter. The longitudinal speed of the vehicle is assumed to vary between a minimum value of 1.4 m/s and a maximum value of 20 m/s. It has been found that when the vehicle is moving at a constant velocity of 3.2 m/s, a heading angle change of 20 degrees can be achieved within 3 seconds with 2% steady state error using a proportional controller. It was observed that at lower speeds, the controller is more sensitive to the steering actuator dynamics and at higher speeds, the controller is more sensitive to the cornering stiffness of tires.