Reference Vehicle Research Articles

LONG-TERM TRACKING OF A SPECIFIC VEHICLE USING AIRBORNE OPTICAL CAMERA SYSTEMS

In this paper we present two low cost, airborne sensor systems capable of long-term vehicle tracking. Based on the properties of the sensors, a method for automatic real-time, long-term tracking of individual vehicles is presented. This combines the detection and tracking of the vehicle in low frame rate image sequences and applies the lagged Cell Transmission Model (CTM) to handle longer tracking outages occurring in complex traffic situations, e.g. tunnels. The CTM model uses the traffic conditions in the proximities of the target vehicle and estimates its motion to predict the position where it reappears. <br><br> The method is validated on an airborne image sequence acquired from a helicopter. Several reference vehicles are tracked within a range of <i>500m</i> in a complex urban traffic situation. An artificial tracking outage of <i>240m</i> is simulated, which is handled by the CTM. For this, all the vehicles in the close proximity are automatically detected and tracked to estimate the basic density-flow relations of the CTM model. Finally, the real and simulated trajectories of the reference vehicles in the outage are compared showing good correspondence also in congested traffic situations.

Wear/comfort Pareto optimisation of bogie suspension

ABSTRACTPareto optimisation of bogie suspension components is considered for a 50 degrees of freedom railway vehicle model to reduce wheel/rail contact wear and improve passenger ride comfort. Several operational scenarios including tracks with different curve radii ranging from very small radii up to straight tracks are considered for the analysis. In each case, the maximum admissible speed is applied to the vehicle. Design parameters are categorised into two levels and the wear/comfort Pareto optimisation is accordingly accomplished in a multistep manner to improve the computational efficiency. The genetic algorithm (GA) is employed to perform the multi-objective optimisation. Two suspension system configurations are considered, a symmetric and an asymmetric in which the primary or secondary suspension elements on the right- and left-hand sides of the vehicle are not the same. It is shown that the vehicle performance on curves can be significantly improved using the asymmetric suspension configuration. The Pareto-optimised values of the design parameters achieved here guarantee wear reduction and comfort improvement for railway vehicles and can also be utilised in developing the reference vehicle models for design of bogie active suspension systems.

City Buses with Alternative Power Trains under Realistic Driving Conditions

City buses with hybrid and battery electric power trains as well as conventional reference vehicles have been examined using a standardized methodology, mainly focusing on exhaust and noise emissions, overall energy efficiency and operational availability. A combination of realistic test drives on bus lanes, test track runs, long term data acquisition and simulation has been utilized to conduct a complete assessment of the technology. First results indicate an improvement over conventional city buses in every technical area.

Ensayos de viento para el Puente de la Constitución de 1812 sobre la Bahía de Cádiz

The 1812 Constitution Bridge over the Cádiz Bay has been subjected to several wind studies and tests using the most advanced methodology and techniques that the current state of the art allows. Full aeroelasticity tests in a boundary layer tunnel have been carried out, taking into account the whole configuration of the bridge during the in-service state, and also considering the most critical stage during the construction. No risk of aerodynamic instability has been found for the design wind speed. Furthermore, static section model tests for determination of static load coefficients for drag, lift and moment, and dynamic section model tests for simulation of the vertical and torsional vibrations of the bridge induced by vortex shedding and buffeting were also carried out. An exhaustive tests program was also developed to investigate the wind action on reference vehicles, evaluating the good performance of the windshield.

Analysis of steering system elasticities and their impact on on-centre handling

This paper deals with the analysis of the elasticities of a steering system regarding the on-centre of the steering system. In the first part, different subsystems of the steering system are analysed in detail. Therefore, several test drives on a steering test rig and a reference vehicle are executed. On the basis of the experimentally determined results, a vehicle and steering system model is built. The parameterised model is used to analyse the characteristics of the steering system in the on-centre handling range. The results show that the elasticities of the steering system have significant influence on the vehicle and steering dynamics response.

Cycle Beating - An Analysis of the Boundaries During Vehicle Testing

Todays vehicle industry is strictly controlled by environmental legislations. The vehicle industry is spending much money on reducing the fuel consumption and fulfilling the emission requirements to make sales possible in different regions in the world. Before introducing a vehicle on the market, it is tested according to standardized driving cycles to specify the vehicle pollutant emissions and fuel consumption. These cycles allow some deviation from the reference vehicle speed during tests, e.g. NEDC allows deviations of ±2 km/h and ±1 s. This paper uses dynamic programming to find fuel optimal velocity profiles, given the allowed deviations of ±2 km/h and ±1 s from reference speed during drive cycle test. By taking advantage of the allowed deviation, the fuel consumption can be reduced by up to 16.56 % according to model results, running NEDC if gear selections are unrestricted (i.e. using automatic gearbox), and up to 5.90 % if changing gears according to the specifications in the drive cycle. Two different optimization goals are investigated, minimum amount of mass fuel consumed and best mileage.

Design method of a hood structure adopting modal analysis for preventing pedestrian’s head injury

This study introduces a new method for decreasing the hood stiffness, by making a hole on the inner hood panel. To determine the most effective hole position on the inner hood panel, the method of modal stiffness was employed, in an attempt to reduce the HIC from a collision between a vehicle and a head-form impactor. FRF (frequency response function) results for the reference vehicle model on head-form impact simulation were obtained. In addition, modal analysis of the entire vehicle model was simultaneously carried out. Subsequently, using the results of these two analyses, dominant frequencies (41.7 Hz and 83.3 Hz) were obtained, which related to deformation of the inner hood panel. Then, adequate hole positions at each modal frequency were selected, and the inner hood panel was improved, by making a hole at these positions. Finally, through head-form impact simulations on the improved vehicle model with the hole, it was demonstrated that the new method applied in this study is acceptable and useful. In the case of the improved vehicle model with a 40 mm diameter hole on the inner hood panel, this showed a significant reduction in the HIC of approximately 12.2%, compared to the original vehicle model.

Phenolic profile, antioxidant and antinociceptive properties of Syringa vulgaris

Syringa vulgaris L. (Common lilac, fam. Oleaeae) has been traditionally used in folk medicine to treat several ailments. In this study, we investigated the chemical composition, antioxidant and antinociceptive activity of S. vulgaris bark and leaf. For identification of the compounds, accurate molecular mass and formula, acquired by LC and electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), and fragmentation patterns given by LC-ESI-MS/MS analyses were used. Altogether 29 phenolics were identified in the extracts, including 15 secoiridoids, 4 cinnamic acid derivatives, 4 flavonoids and 6 low molecular weight phenols. Based on the chromatograms, syringin and oleuropein are the main components of the bark, and rutin and oleuropein of the leaf. The radical scavenging activities of the extracts and the major constituents were also investigated by the DPPH and ABTS assays. Both extracts showed remarkable antioxidant activities in both tests. In vivo analgesic activity of the methanolic extract of Syringae folium and cortex was also tested using the hot-plate test on mice. Basal reaction time was determined, and two doses of each extract (100 mg/kg and 200 mg/kg body weight) were administrated to two groups. Aspirin (ASA) (200 mg/kg) was used as reference standard and vehicle served as the control. Our investigations show that both extracts present similar analgesic effect as ASA at a dose of 200 mg/kg [1].

Development of the World-wide harmonized Light duty Test Cycle (WLTC) and a possible pathway for its introduction in the European legislation

This paper presents the World-wide harmonized Light duty Test Cycle (WLTC), developed under the Working Party on Pollution and Energy (GRPE) and sponsored by the European Union (with Switzerland) and Japan. India, Korea and USA have also actively contributed. The objective was to design the harmonized driving cycle from “real world” driving data in different regions around the world, combined with suitable weighting factors. To this aim, driving data and traffic statistics of light duty vehicles use were collected and analyzed as basic elements to develop the harmonized cycle. The regional driving data and weighting factors were then combined in order to develop a unified database representing the worldwide light duty vehicle driving behavior. From the unified database, short trips were selected and combined to develop a driving cycle as representative as possible of the unified database. Approximately 765,000km of data were collected, covering a wide range of vehicle categories, road types and driving conditions. The resulting WLTC is an ensemble of three driving cycles adapted to three vehicle categories with different power-to-mass ratio (PMR). It has been designed as a harmonized cycle for the certification of light duty vehicles around the world and, together with the new harmonized test procedures (WLTP), will serve to check the compliance of vehicle pollutant emissions with respect to the applicable emissions limits and to establish the reference vehicle fuel consumption and CO2 performance.

Gaseous Emissions from Light-Duty Vehicles: Moving from NEDC to the New WLTP Test Procedure.

The Worldwide Harmonized Light Duty Test Procedure (WLTP), recently issued as GTR15 by UNECE-WP29, is designed to check the pollutant emission compliance of Light Duty Vehicles (LDVs) around the world and to establish the reference vehicle fuel consumption and CO2 performance. In the course of the development of WLTP, the Joint Research Center (JRC) of the European Commission has tested gaseous emissions of twenty-one Euro 4-6 gasoline and diesel vehicles, on both the current European type approval test procedure (NEDC) and the progressive versions of the WLTP. The results, which should be regarded just as an initial and qualitative indication of the trends, demonstrated minimal average differences between CO2 emissions over the NEDC and WLTP. On the other hand, CO2 emissions measured at JRC on the NEDC were on average 9% higher than the respective type approval values, therefore suggesting that for the tested vehicles, CO2 emissions over WLTP were almost 10% higher than the respective NEDC type approval values. That difference is likely to increase with application of the full WLTP test procedure. Measured THC emissions from most vehicles stayed below the legal emission limits and in general were lower under the WLTP compared to NEDC. Moving from NEDC to WLTP did not have much impact on NOx from gasoline vehicles and CO from diesel vehicles. On the contrary, NOx from diesel vehicles and CO from low-powered gasoline vehicles were significantly higher over the more dynamic WLTP and in several cases exceeded the emission limits. Results from this study can be considered indicative of emission patterns of modern technology vehicles and useful to both policy makers and vehicle manufacturers in developing future emission policy/technology strategies.

EQUIVALENCY FACTOR USING OPTIMIZATION FOR INDIAN MIXED TRAFFIC CONDITION

The term Equivalency Factor as PCE was introduced in 1965 by HCM. And after that, considerable research effort has been carried toward to estimate PCE value. The present empirical study is to determine the dynamic equivalency factor for mix traffic condition in Indian context. For that car as reference vehicle is considered this termed as Dynamic Car Unit (DCU). Speed and Volume studies during the peak hour are carried out and based on the observed data dynamic car unit using modified homogenization coefficient approach is calculated. The wide ranges of DCU values for different location are observed based on the side friction, composition, wide ranging traffic characteristics and lane width. To have the unique value of the DCU optimization method is used. Based on the optimization final values of the DCU are frizzed which will be utilised to present the traffic stream volume in terms of equivalent passenger cars.

Control algorithm of electric vehicle in coasting mode based on driving feeling

Coasting in gear is a common driving mode for the conventional vehicle equipped with the internal combustion engine (ICE), and the assistant braking function of ICE is utilized to decelerate the vehicle in this mode. However, the electric vehicle (EV) does not have this feature in the coasting mode due to the relatively small inertia of the driving motor, so it will cause the driver cannot obtain the similar driving feeling to that of the conventional vehicle, and even a traffic accident may occur if the driver cannot immediately adapt to the changes. In this paper, the coasting control for EV is researched based on the driving feeling. A conventional vehicle equipped with continuously variable transmission (CVT) is taken as the reference vehicle, and the combined simulation model of EV is established based on AVL CRUISE and MATLAB/Simulink. The torque characteristic of the CVT output shaft is measured in coasting mode, and the data are smoothed and fitted to a polynomial curve. For the EV in coasting mode, if the state of charge (SOC) of the battery is below 95%, the polynomial curve is used as the control target for the torque characteristic of the driving motor, otherwise, the required torque is replaced by hydraulic braking torque to keep the same deceleration. The co-simulation of Matlab/Simulink/Stateflow and AVL CRUISE, as well as the hardware-in-loop experiment combined with dSPACE are carried out to verify the effectiveness and the real-time performance of the control algorithm. The results show that the EV with coasting braking control system has similar driving feeling to that of the reference vehicle, meanwhile, the battery SOC can be increased by 0.036% and 0.021% in the initial speed of 100 km/h and 50 km/h, respectively. The proposed control algorithm for EV is beneficial to improve the driving feeling in coasting mode, and it also makes the EV has the assistant braking function.

Control allocation strategies for an electric vehicle with a wheel hub motor failure

Three fault-tolerant control strategies for electric vehicles with wheel hub motors are presented and compared, which are all based on the control allocation principle. The main objective is to maintain the directional stability of the vehicle in case of a component failure during high speed manoeuvres. Two simplified strategies that are suited for on-board implementation are derived and compared to an optimal control allocation strategy and a reference vehicle with a basic electronic stability control system. The occurring faults are considered to be in the electric high-voltage system that can arise in wheel hub motors. All three control allocation strategies show improved re-allocation of traction forces after a severe fault, and hence an improved directional stability. However, the performance of both simplified algorithms shows limitations in case of force demands outside the capabilities of the respective actuator. This work shows that vehicle safety is increased by the proposed fault-tolerant control strategies.

Direct yaw moment control for electric and hybrid vehicles with independent motors

Direct yaw moment control is an effective means to enhance vehicle stability and handling. The majority of the latest direct yaw moment control works employ sliding mode control to generate the target yaw moment. In this paper, a new sliding mode-based direct yaw moment control method is proposed for electric and hybrid vehicles equipped with independent motors. This method employs a novel switching function design to simultaneously track the desired yaw rate and vehicle side-slip. Comparative simulation results show that the proposed method outperforms the conventional direct yaw moment control method in terms of tracking the reference yaw rate, vehicle path and vehicle side-slip in various challenging driving scenarios.

Lane departure assistance based on balanced longitudinal slip ratio differential braking control

This paper presents studies on differential braking-based Lane Departure Assistance System (LDAS). The dynamic threshold of Time to Lane Crossing (TLC), determined by vehicle heading error, speed, road adhesion and reaction time of human-machine system, is studied to activate driving assistance. Based on 2-DOF reference vehicle model and driver preview model, the desired yaw rate to avoid lane departure is calculated. To avoid loss of lateral stability during braking, strategies for the distribution of braking force are developed based on balanced longitudinal slip ratio, which aim to limit the slip ratio on all wheels. The Hardware in Loop (HIL) test bench is established to evaluate the rapid prototyping of LDAS. Results show that the proposed methods can confine the vehicle in lane effectively with lateral stability maintained and operate robustly, benefiting from timely assistance, model-independent control algorithm, and small and balanced slip ratio.

1312 路面摩擦係数に依らない実路でのタイヤ状態推定の提案

In order to control vehicle behavior, it is essential to estimate the tire force accurately. However, even today it is difficult to detect the tire performance degradation before the deterioration of vehicle dynamics in real time. This is because the tire force estimation is usually conducted by comparing the actual vehicle motion with the onboard reference vehicle model motion. Therefore, such conventional estimators do not perform well if there is significant difference between the actual vehicle and the model behavior. In this paper, a new tire state estimation method based on tire force characteristic is proposed. In addition, the estimator for tire-road surface friction coefficient ,u is proposed by using this geometric relationship.

Evaluation of a vehicle model and ABS/TCS controllers

This paper evaluates a mathematical vehicle model, and an antilock braking (ABS) and traction control system (TCS) with a software package, CarSim. The mathematical vehicle model is developed to analyse dynamic performance and to design various safety control systems. Wheel slip controllers for antilock braking and traction control systems are included to improve vehicle response and to increase safety on slippery roads. The results show that the vehicle model agrees closely with the reference vehicle model under various driving conditions. The wheel slip controllers were applied to both models and they worked well, demonstrating that the controllers are robust and reliable. They were also determined to improve lateral stability as well as longitudinal stability when a vehicle is manoeuvred on slippery roads.

A modified structure internal model robust control method for the integration of active front steering and direct yaw moment control

Taking into account the nonlinearity of vehicle dynamics and the variations of vehicle parameters, the integrated control strategy for active front steering (AFS) and direct yaw control (DYC) that can maintain the performance and robustness is a key issue to be researched. Currently, the H ∞ method is widely applied to the integrated control of chassis dynamics, but it always sacrifices the performance in order to enhance the stability. The modified structure internal model robust control (MSIMC) obtained by modifying internal model control (IMC) structure is proposed for the integrated control of AFS and DYC to surmount the conflict between performance and robustness. Double lane change (DLC) simulation is developed to compare the performance and the stability of the MSIMC strategy, the PID controller based on the reference vehicle model and the H ∞ controller. Simulation results show that the PID controller may oscillate and go into instability in severe driving conditions because of large variations of tire parameters, the H ∞ controller sacrifices the performance in order to enhance the stability, and only the MSIMC controller can both ensure the robustness and the high performance of the integrated control of AFS and DYC.

Turboelectric distributed propulsion benefits on the N3-X vehicle

Purpose – The purpose of this article is to present a summary of recent study results on a turboelectric distributed propulsion vehicle concept named N3-X. Design/methodology/approach – The turboelectric distributed propulsion system uses multiple electric motor-driven propulsors that are distributed on an aircraft. The power to drive these electric propulsors is generated by separately located gas turbine-driven electric generators on the airframe. To estimate the benefits associated with this new propulsion concept, a system analysis was performed on a hybrid-wing-body transport configuration to determine fuel burn (or energy usage), community noise and emissions reductions. Findings – N3-X would be able to reduce energy consumption by 70-72 per cent compared to a reference vehicle, a Boeing 777-200LR, flying the same mission. Predictions for landing and take-off NOX are estimated to be 85 per cent less than the Tier 6-CAEP/6 standard. Two variants of the N3-X vehicle were examined for certification noi...

Fictional IR and imagination: Advancing narrative approaches

AbstractIn the field of International Relations (IR), narrative approaches and an alternative way of writing seem to have gained growing attention in recent scholarship. Autoethnography and autobiography can be taken as primary examples. The article aims to advance this growing scholarship by proposing the concept of fictional IR. The idea is concerned with how to use the imagination in IR. I suggest that fiction writing can become a method for dealing with lack of information and contingency surrounding it. Fictional IR is more than reading and using fiction as a reference source or vehicle for analysis. It can incorporate the employment of fiction writing in IR scholarship. One of the benefits could be to articulate sensitive and complicated problems in a more flexible and imaginative way, making the most of the power of story and imagination. It should be stressed that the focal point is to write fiction; it is not to write about fiction. To support this suggestion, the article offers a short fictional-factual story. By using imagination, creating characters, combining data with fictional narrative, or with one's own experience, I believe that more original and empathetic IR writing is possible.