International Journal of Heavy Vehicle Systems (59 papers in press)
Dynamic modelling and design of tracked vehicle suspension system using magnetorheological valve
by Sung Hoon Ha, Min-Sang Seong, Juncheol Jeon, Seung-Bok Choi
Irregularity model of welded rail joint and wheel
by Kaiyun Wang
Abstract: Due to the irregularity excitation of welded rail joints (WRJs), the dynamic impacting force between the wheel and the rail would be obviously enhanced. According to measured irregularities of WRJs in heavy
Keywords: welded rail joint; heavyhaul railway; wheelrail interaction; irregularity; vehicletrack coupled dynamics.
Introducing wheel-rail adhesion control into longitudinal train dynamics
by Qing Wu, Maksym Spiryagin, Colin Cole, Yan Sun
Abstract: Conventional Longitudinal Train Dynamics (LTD) simulations apply a number of assumptions regarding wheel-rail adhesion, and wheel-rail adhesion control has not previously been considered. This paper introduces locomotive wheel-rail adhesion control into LTD using co-simulation and parallel computing techniques. An in-house LTD simulator was connected to a commercial MBS dynamics simulator using the TCP/IP protocol. A heavy haul train with the configuration of three locomotives and 150 wagons was modelled. The wagons were modelled in the LTD simulator while the locomotives were modelled in the MBS simulator. The locomotive models were three-dimensional models that included wheel-rail contact models and adhesion control models. Simulations of locomotives were processed in parallel using three computer cores. Co-simulations with and without the consideration of curve lubrication were conducted and compared with a conventional LTD simulation. Computing times with and without parallel computing were also compared. The results show that, when compared with conventional LTD simulations, wheel-rail adhesion control generates evident differences for maximum traction forces, average train speeds, maximum in-train forces and force patterns. With three computer cores, parallel computing reduced the computing time by about 46% from about 3.7 hours to about 2.0 hours.
Keywords: longitudinal train dynamics; wheel-rail contact; adhesion control; traction modelling; parallel computing;co-simulation.
Research on loaded brake performance test of trucks
by Wanyou Huang, Yanyan Fan, Mingjin Yu
Abstract: As regulated by the truck inspection specification in the China National Standard GB21861-2014 that, from the 1st March of 2017 a new detection program should be added to test the loaded braking performance for trucks that have more than three (including three) axles. And it is specified that the trucks should be lift loaded by brake test platform. In this article, the axle load model of a three-axle truck upon lift loading is built, and the calculation model of vehicle centroid position is created as well. The effectiveness of the axle load model is verified by real vehicle test with a three-axle heavy duty van. The maximum relative error between model calculation results and real test values is 3.17%, which indicates that the axle load model is valid. Based on the axle load model, analysis is conducted to get impact laws of lifted height, wheelbase, centroid position and composite stiffness on the lift loaded axle load, which provides a basis for the vehicle braking performance test. According to the results of real vehicle tests, the maximum braking force of the first, second and third axles is increased by 30.6%, 73.3% and 5% after the respective axle is lift loaded. The growth of both axle load and braking force reach a maximum when lift loading is applied on the second axle. Therefore, it is feasible to do loaded brake tests on the second axle using the test method of lift loading. On the other hand, as the growth of braking force is not obvious when the third axle is lift loaded, so it is inadvisable to do lift loaded brake tests on the third axle.
Keywords: truck; braking performance; load test; anti-force brake test platform; axle-load models.
Study of a steering model for four-axle 8x8 off-road vehicles
by Yun-Jui Chung, Chung-Hsien Chuang, Yung-Chi Chang, Tyng Liu
Abstract: The purpose of this study is to establish a steering model for a four-axle 8x8 vehicle, which provides the design of the assisted steering system. To obtain the best steering performance, this system aims to minimise the turning radius. In this study, the steady-state mathematical steering model of this vehicle is established and the actual physical parameters are added to this model. By actually driving the vehicle, the model is verified and the results show that the model can accurately predict the steering behaviour of the vehicle. After correction, the model is added to assist the steering of the fourth axle and find the optimal steering mode. To evaluate the design, this model inputs the functions of time and steering wheel angle and outputs the tracks of driving this vehicle. We verify the steering assistance design of this vehicle by comparing the driving tracks with and without it.
Keywords: four-axle vehicles; turning radius; mathematical model; steering assistance.
Relative navigation control of articulated vehicles based on LTV-MPC
by Guoxing Bai, Yu Meng, Qing Gu, Weidong Luo, Li Liu
Abstract: The automation of articulated vehicles is an important trend of the intelligent transportation system in the mining industry. The relative navigation is a key technology in automatic vehicles. One of the challenges in the relative navigation of the articulated vehicle is that the system constraints may cause the actuator saturation and other problems. In order to solve these problems, this paper presents a relative navigation control method based on Linear Time Varying Model Predictive Control (LTV-MPC). This control method can explicitly take the system constraints into account. The performance of the controller is verified by simulation and experiment. The results show that the articulated vehicle with the LTV-MPC controller can track the target heading direction, and the steady-state error is less than 0.3 rad. The relative navigation controller based on LTV-MPC can be used to improve the automatic driving performance of the articulated vehicle.
Keywords: articulated vehicle; relative navigation; motion control; LTV-MPC; nonlinear systems.
Estimation of friction surface temperature of a dry clutch
by Tolga Cakmak, Muhsin Kilic
Abstract: This paper presents an approach to estimate the temperature on the friction surface of a dry clutch. The study comprises both experimental measurements and transient thermal numerical analysis of heavy duty truck clutches for the successive engagements on a sloping road. Compared with previous mathematical models in the literature, pressure plate surface convection coefficient, energy dissipation, engagement duration and variation of the clutch housing air temperature were obtained on the basis of experimental data and have been applied as input in the 3D clutch transient thermal finite element analysis. Simulation results show that the design of the clutch plate has a significant effect on the temperature rise at the friction surface.
Keywords: dry clutch; energy dissipation; engagement duration; finite element analysis; transient thermal simulation.
Modelling, parametrisation and validation of a truck steering system to predict the steering-wheel torque
by Jan Loof, Igo Besselink, Henk Nijmeijer
Abstract: The prediction of the steering-wheel torque in a steering system is a challenging subject. The steering system of a truck consists of many components, including a hydraulic power-steering system. A model is developed that includes the most important components. A Wheatstone bridge is used to model the hydraulic valve system. A flexible supply hose and compressible fluid in the cylinder chamber are taken into account. The model is parametrised using test-bench measurements. The model is validated by means of additional measurements on the same test-bench. The model is verified for quasi-static conditions and up to a frequency higher than a driver will ever use. The predictions of the steering-wheel torque, steering-wheel angle and pressures in the system are accurate for high torque amplitude inputs. For small inputs the model is still able to predict the steering-wheel torque with an error smaller than 10%.
Keywords: commercial vehicle; hydraulic power-steering; Wheatstone bridge; steering system; steering-wheel torque prediction; parametrisation.
Ground-watching navigation for trailer-steering control
by Qiheng Miao, David Cebon
Abstract: This paper discusses two ground-watching navigation strategies for path-following control of a steered trailer at low speeds. Such systems provide navigation information by processing the features of the road surface in successive images. Theoretical performance of the systems was initially investigated in simulation. Field testing was conducted for three manoeuvres: a straight line, a lane change and a 90
Keywords: heavy goods vehicles; active trailer steering; ground-watching navigation; off-highway;.
Development for generalised multi-axle steering vehicle handling
by Xiang Chen, Kong-hui Guo
Abstract: This paper devotes its main effort to develop the generalised multi-axle steering vehicle handling for more comprehensive analysis with the factors of vehicle body roll, multi-axle, unsprung mass, steering centre distance, steering ratio coefficient and steering delay. A linear vehicle dynamic model is established first. Then,the multi-axle steering vehicle handling is analysed from the two aspects of steady-state and transient-state. For the steady-state, the expressions of equivalent wheelbase and steady factor are derived from the generalised vehicle dynamic equations, and some special conditions are discussed in detail. For the transient-state, the expressions of frequency characteristics and root locus are deduced and the influences of steering delay and steering ratio coefficient to multi-axle steering vehicle handling are analysed in depth. The corresponding results derived from the generalized dynamic model can be used for analysing the various influences on multi-axle steering vehicle handling.
Keywords: multi-axle steering vehicle handling; vehicle dynamic model; steady-state characteristics; transient-state characteristics.
Active fault tolerance control for active suspension with control input time-delay and actuator gain variation fault
by Hongbo Wang
Abstract: An active suspension system subject to control input time-delay and actuator gain fault is considered in this paper. System dynamics models with time-delay and gain fault are built. A sliding-mode controller is designed to maintain the stability for the time-delay system. By employing a robust observer and residue errors, the gain fault is detected and diagnosed. The control law reconfiguration is adopted to realise the active fault tolerance control. The act-and-wait control is applied for the active suspension nonlinear system. Comparative simulation results for a quarter-car active suspension system are presented to show the effectiveness of the adopted control scheme.
Keywords: active suspension; time delay; gain fault; fault tolerance control.
New method to predict truck-semitrailer jackknifing effect
by Roberto Spinola Barbosa
Abstract: A new method based on two articulated bodies with internal inertial force, similar to the structural buckling effect, is proposed to describe the unstable yaw relative angular movement between truck and semitrailer, known as jackknifing. An analytic expression is derived from the proposed linear model, allowing the prediction of the deceleration limit prior to the yaw instability phenomenon. The influences of the relevant contributing factors, such as vehicle mass, brake distribution, height of center of mass, vertical load transfer and lateral tyre stiffness, are considered. A detailed non-linear model with 19 degrees of freedom is developed and used as a simulation tool to verify dynamic performance. The analytical results of the jackknife effect were validated by comparison with the instability tendency simulated with a complete vehicle dynamic model. The results show good agreement between the proposed analytical expression and the numerical simulation. The proposed analytic expression is independent of the vehicle speed and does not require a stability analysis or an integration process, as other techniques available in the literature.
Keywords: jackknifing; truck; dynamic; safety; instability.
Building a novel dynamics rollover model for critical instability state analysis of articulated multibody vehicles
by Qingyuan Zhu, Chaoping Yang, Huosheng Hu, Xiongfeng Wu
Abstract: Articulated wheel loaders in the construction industry have poor lateral stability and a high rate of accidents owing to their multibody structure and uneven working fields. In order to realise early rollover warning and active control, it is necessary to explore the mechanism of instability and the change rules of dynamics parameters. This paper proposes a novel dynamics rollover model with six degrees of freedom for modelling the instability process of an articulated wheel loader. The proposed rollover model is compared with a virtual prototype and a 1:5 scale-down physical prototype under four typical working conditions to verify its reliability, and its accuracy is investigated via a rotation motion under a constant steering angle under the critical state of rollover. Finally, the dynamics rollover model is used to investigate the influence of different kinematic parameters on lateral stability of an articulated wheel loader with steady-state margin angle as stability index.
Keywords: articulated wheel loader; dynamics model; lateral stability.
Analysis and practical validation on a multi-linkage scissor platforms drive system for the satellite test facilities
by Nor Mohd Haziq Norsahperi, Salmiah Ahmad, Siti Fauziah Toha, Iskandar Al-Thani Mahmood
Abstract: This paper evaluates a new method for measuring the reaction forces on the multi-linkages scissor mechanism driven by a ball-screw system. Unlike the previous approach introduced by Spackman, the overall detailed structures were not considered. In this paper, the proposed method took into account all reaction forces on the designed linkages to evaluate accurate actuators sizing. The fusion of the structural-virtual work (SV) analysis overcomes the problems associated with the previous conventional technique, whereby the reaction forces on each linkage where measured to avoid the over-sizing of driving system, and also to sustain the system performance with cost reduction. The idea was proven in three ways: analytical analysis, simulation analysis and experimental analysis based on the developed prototype. In addition, to ensure the results are acceptable to the practitioners in this field, a dynamic study was conducted to observe the effect of speed variations on the driving system. From the simulation performance analysis, it was discovered that the estimated torque was reduced by 29% as compared to the conventional approach. The 12% error between the result from simulation and the ones from the experiment has suggested that the SV method is superior to the conventional analysis, where the error between the conventional analysis and the hardware is 60%. The successful method proposed in this paper can be further implemented for all multi-linkages systems in a heavy vehicle used in industry that requires accurate actuators sizing.
Keywords: scissor mechanism; motion study; static analysis; dynamic analysis; drive system; satellite facilities.
Improving curving performance of a straddle-type monorail vehicle by using semi-active devices
by Ali Suat Yıldız, Selim Sivrioğlu
Abstract: This paper is concerned with improving the curving performance of monorail vehicles, which are one of the modern mass transport systems, by using semi-active magnetorheological (MR) dampers. Controlling the curving dynamic of the monorail vehicles with semi-active devices is a new research area. The considered monorail vehicle has one segment supported by two bogies. As a secondary suspension, lateral and vertical MR dampers are taken into consideration in addition to air suspensions. Control performances of the robust Hinf and adaptive control are investigated and compared with a passive case along a designed road profile. Parametric uncertainties in running tyres and vehicle mass are taken into consideration in the control simulations. Simulation results show that the designed controllers improved the roll, yaw and vertical motions of the monorail vehicle when compared with uncontrolled and passive cases. These improvements provide better comfort and safer conditions, and a small turning radius can be achieved by monorail vehicles equipped with the semi-active suspension system.
Keywords: semi-active suspension; MR damper; adaptive controller; monorail vehicle; Hinf control.
On the dynamics of a four-axle railway vehicle with dry friction yaw damping
by Hans True, Anders H. Christiansen, Susanne E. Knutz, Lene B. Rasmussen
Abstract: The dynamics of a railway vehicle with four wheel sets and dry friction yaw damping is investigated. The stick/slip mechanism is considered. The speed of the vehicle is the control parameter. The first bifurcation points are found. The results demonstrate the influence of the stick/slip on the dynamics of the vehicle. For speeds above the critical speed the symmetry of the dynamical problem is broken and may result in asymmetric periodic or erratic - possibly chaotic - motions. Three different numerical integrators are applied and their effectiveness is compared. Dry friction damping is still used in almost all freight wagons in the world owing to the low costs of the elements.
Keywords: non-smooth dynamics; railway vehicle dynamics; bifurcations.
Optimum operational conditions of mining trucks based on the vibrational health risk of the driver
by Mohammad Javad Rahimdel, Mehdi Mirzaei
Abstract: This paper aims to propose the optimum payload and speed limit and load geometry for a heavy duty 60-ton truck in Sungun Copper Mine of Iran as a case study to keep the vibrational health risk at the lowest possible level while maintaining the production rate at the planned level. These trucks need special consideration because of their specific hydro-pneumatic suspension system, large size, and payload capacity. There is limited evidence considering the effect of speed, payload and load geometry on the vibrational health risk of mining trucks. Also, there is not much research to suggest the practical conditions helping to drive the trucks in safe conditions, along with keeping the production rate at the planned level. The Root Mean Square (RMS) of vibrations at different operational conditions was obtained. Then, an optimization problem was developed to propose the optimum payload and truck speeds at various conditions. The optimum payload was 65 tons. The optimum speed of loaded truck was obtained in the range of 30 to 35 km/h at good roads and 15 km/h at poor roads. Also, the optimum speed range of empty truck was in the range of 15 to 20 km/h. Operational conditions have a significant effect on the RMS values. Uniform payloads and materials accumulated on the left side can have the lowest and highest effects on the vibrational health risk, respectively. This paper addresses the mine managers to propose practical solutions for reducing the vibrational health risk of mining trucks, as well as keeping the production rate at the planned level.
Keywords: mining truck; whole body vibration; optimisation; regression analysis.
Adaptive online estimation of centre of gravity height for commercial vehicles
by Zhi-Jun Fu, Bin Li
Abstract: A novel parameter error-driven robust estimation method is proposed for online estimation of centre of gravity (CG) height of a tour bus vehicle. Unlike the commonly used recursive least squares (RLS) method, a parameter error-driven updating law is synthesised to ensure improved performance in terms of steady-state error and robust convergence. The stability of the proposed estimation method is illustrated using the Lyapunov approach. The proposed CG estimation method is based on directly measurable lateral acceleration and relative roll angle of the sprung mass, while the high order signals are eliminated using the filtering approach. The validity of the proposed estimation method is illustrated through implementations in TruckSim platform. Simulation results show that the proposed estimation method can yield accurate online estimation of the CG height, together with effective suspension roll stiffness and damping properties.
Keywords: centre of gravity height; commercial vehicles; parameter estimations; roll dynamics; adaptive estimation.
Low speed performance based standards for Nordic countries
by Fredrik Bruzelius, Sogol Kharrazi
Abstract: Performance Based Standards (PBS) is an effective regulator policy that can address variation complexity in vehicle combinations. This paper investigates aspects of using computer simulation and mathematical models to assess the performance of vehicle combinations in low speed manoeuvring, in particular on roundabouts. A set of 22 vehicle combinations, including existing conventional heavy vehicles as well as prospective high capacity vehicles, is used to study the effects of turn angle and road surface conditions on the friction demand and swept path measures. Simulation results suggest that the friction demand measure is dependent on the available grip. This makes it hard to interpret and may not be suitable in the PBS framework. The swept path measure is relatively unaffected by friction levels, and can hence be calculated with simple and robust expressions not considering the road interaction. However, turn angle affects the swept path measure considerably, and should be addressed when designing the PBS scheme implementation into the legislations.
Keywords: low speed performance based standards; high capacity transport vehicles; friction demand; swept path; vehicle performance assessment.
A new numerical method for analysing the interaction of a bridge structure and travelling cars due to multiple high-speed trains
by Mehmet Akif Koc, Ismail Esen, Mustafa Eroglu, Yusuf Cay
Abstract: Dynamic interaction between a 10-DOF high-speed train model and a simply supported bridge beam is studied. The second-order coupled equations of the bridge beam and train are derived using the Lagrange method. The proposed method provides considerable advantage by taking 0.5% of the time needed in analysing of the train-bridge interaction (TBI) previously given in the literature using the finite element method (FEM). The presented modelling, which includes the dynamic forces on the train components from the interaction, is created in a manner that it may concern both train and bridge engineers. It is shown that, while moving on the bridge, the dynamic forces on the train body, front and rear bogies, and wheels, as well as the bridge, are significantly affected by the speed and mass of the train, along with the flexibility of the bridge. Effects of multiple cars are included in the modelling.
Keywords: high-speed train; bridges; dynamic interaction; dynamic forces; successive loading.
Research on partially filled characteristics of vehicular hydrodynamic retarders
by Lingxing Kong, Wei Wei, Hongbin Mu, Qingdong Yan
Abstract: Hydrodynamic retarders are widely used on heavy vehicles as auxiliary braking components. Figuring out the partially filled characteristics is of practical significance for the design and control of retarders. In this paper, torque characteristics under variable filling rate of a dual-torus hydrodynamic retarder are studied by theoretical deduction as well as CFD simulation, and the results are verified with experimental data. 1D flow theory was implemented to calculate the circulating flow-rate and brake torque on the basis of energy balance equation. 3D CFD simulation was conducted using commercial code CFX, and VOF model was adopted to simulate air-oil two-phase flow when the chamber is partially filled. The results showed that, unlike the common assumption that brake torque is in direct proportion to the filling ratio of the chamber, the torque presents a non-linear relationship versus filling ratio. This is mainly caused by the non-linear distribution pattern of the circulating flow-rate. In the bench test, the filling ratio is derived by monitoring the flow-rate into and out from the chamber, and the experimental results validated the non-linear relationship between brake torque and filling ratio.
Keywords: brake torque characteristics; CFD; filling ratio; vehicular hydrodynamic retarder; two-phase flow.
Review on NOX emissions from using biodiesel blends in diesel engines
by Mahmoud Sayed, Mohamed Elhemaly
Abstract: Environmental pollution is a major problem in all countries around the world. ICE The Internal Combustion Engine (ICE) is considered one of the main sources of emissions, thus most countries are interested in using biodiesel as an alternative fuel. Scientists, researchers, and manufacturers are facing the challenge of reducing fuel burning emissions and at the same time achieving the main technological requirements, such as increasing the vehicle performance, decreasing the fuel consumption, etc. Some of recent studies indicate that many vehicles and movable equipment accept the use of biodiesel blends (Bb). Mainly, the new engines can be operated with Bb of 20%, 30% and B100 (pure biodiesel). Nitrogen oxides (NOx) represent one of the exhaust gases that have a great impact on environmental conditions. This work presents an analytical study of NOx emissions, summarising the practical solutions to reduce NOx emitted from diesel engines burning Bb.
Keywords: biodiesel fuels; biodiesel blends; NOx emissions; diesel engine; internal combustion engine.
A new approach to modelling the hitch joint of a tractor semi-trailer using virtual Pacejka tyre model
by Mohamad Hafiz Harun, Khisbullah Hudha, Pakharuddin Mohd Samin, Saiful Anuar Abu Bakar, Zulkiffli Abd Kadir
Abstract: In this study, a new approach to modelling of the hitch joint of a tractor semi-trailer is proposed by adopting the virtual Pacejka tyre model. The virtual Pacejka tyre model is connected with a 16 DOF tractor semi-trailer combination in Matlab-Simulink software and verified using validated software known as TruckSim. Two sets of simulations are conducted in the verification process, which involves a double lane change (DLC) and steep steer cornering (SSC) test. It is observed from the results that by modelling the hitch joint as a virtual Pacejka tyre model, the behaviour of the developed model closely follows the behaviour of the validated TruckSim model.
Keywords: tractor semi-trailer; hitch joint; double lane change; step steer cornering.
Investigation of diesel oilLPG content fuel use in heavy duty diesel engines with common rail system
by Máté Zöldy
Abstract: After the diesel scandal, the replacement of diesel fuel in heavy duty segments is an up-do-date issue to investigate. Liquified petrolum gas (LPG) could be one of the alternatives. In our research, we investigated different LPG-diesel blends and measured engine CO, CO2, NOx and particulate emissions, fuel consumption and torque, and also investigated combustion characteristics. Results show that, based on its very different chemical composition, LPG is not an optimal substitute for diesel fuels.
Keywords: diesel substitutes; emission reduction; LPG.
Impact of a modified braking valve for static and dynamic characteristics of pneumatic braking systems of agricultural trailers
by Zbigniew Kaminski, Krzysztof Kulikowski
Abstract: The pneumatic braking systems of agricultural trailers contain brake valves with adjustable predominance of the output pressure relative to the control pressure. The goals of our study were to improve the static and dynamic properties of agricultural trailer pneumatic braking systems by modification of brake valve construction with implementing a throttle valve to the predominance device. The proposed correction device makes the intensity of the predominance effect depends on the rate of pressure rise in control chamber of the braking valve. Initial testing of three braking systems of agricultural trailers has confirmed the effect of modifying relay emergency valve to shortening the response time of their braking systems, concomitantly maintaining a follow-up action under steady state conditions.
Keywords: braking dynamics; vehicle braking systems; road safety; air brake systems; agricultural trailers; relay emergency valve.
A virtual test platform for railway draft gear designs
by Qing Wu, Colin Cole, Maksym Spiryagin, Weihua Ma, Shihui Luo
Abstract: Draft gears are important shock absorbers in railway vehicle operations. Draft gear design and assessment processes commonly use results from physical drop-hammer tests, vehicle impact tests and laboratory rig tests, which all use quite different impact velocity ranges and impact severities from each other. Owing to the velocity-dependent characteristics of friction and viscous damping, draft gears can be better designed and assessed by using comprehensive draft gear test simulations. This paper developed a multipurpose virtual test platform for draft gear designs; the virtual platform can conduct drop-hammer test simulations, vehicle impact test simulations and laboratory rig test simulations for different types of draft gear using different draft gear models. The development for the virtual platform has used a versatile draft gear model that can simulate a number of different draft gear designs by using one model template; it has also used a multipurpose simulation strategy that can simulate different draft gear tests using the same dynamics model. Three virtual test examples are also presented in this paper.
Keywords: draft gear design; virtual platform; drop-hammer; vehicle impact; laboratory rig.
Integrated active steering control strategy for autonomous articulated vehicles
by Bo Wang, Hongshan Zha, Qin Li, Xiaobo Wang
Abstract: An integrated active steering control strategy for tractor and trailer unit of articulated vehicles is presented in order to achieve both autonomous and safe motion. Without drivers supervision or input, the tractor and trailer controllers are designed to preview and follow the demanded path automatically and safely. The system is implemented by integrated active steering control based on model predictive control (MPC). A driver preview model, used to preview and store the lateral position of the road path with time progressing, is introduced to provide information regarding the demanded path for the controller. Based on the MPC theory, the integrated active steering controller of the tractor and trailer is designed to minimise path-tracking deviation while taking lateral stability into account. The path-tracking deviation is measured by the distance between the CoG (centre of gravity) of tractor and trailer with respect to the demanded path, while lateral stability considers lateral acceleration and side-slip angle. The above index can be addressed via coordinated optimisation on the performance index according to different vehicle conditions. Finally, manoeuvrability and stability of the articulated vehicle under the proposed control strategy are studied and verified by simulations at low speed and high speed based on TruckSim-Simulink. The results confirm that the proposed integrated active steering system, as desired, is capable of keeping the articulated vehicle automatically following the demanded path with high stability. The lateral stability and path-tracking of both tractor and trailer are significantly improved.
Keywords: autonomous articulated vehicle; integrated active steering; lateral stability; model predictive control.
Torsional vibrations in heavy-duty truck powertrains with dual mass flywheels
by Lina Wramner
Abstract: Many of the measures taken to improve combustion engine efficiency lead to higher torsional vibrations. For heavy-duty commercial vehicles it is foreseen that the conventional flywheel and clutch will not be able to sufficiently reduce those increased engine torsional vibrations to the driveline. In this paper, the steady-state torsional vibrations in a heavy-duty truck powertrain are studied. The focus is engine excited vibrations at high load within operating speed range. Vibration phenomena in a conventional heavy-duty powertrain and in powertrains equipped with dual mass flywheels are studied. It is shown how the use of a dual mass flywheel can enable down-speeding and increased engine torque with maintained or reduced levels of torsional vibrations.
Keywords: torsional vibrations; powertrain; driveline; heavy-duty truck; dual mass flywheel; DMF; resonances; simulation.
On the control strategies for vehicle stability enhancement
by Amro Elhefnawy, Hossam Ragheb, Al-Hossein Sharaf, Shawky Hegazy
Abstract: Currently, vehicle stability enhancement is the main objective of automotive suppliers to enhance the vehicle overall performance and handling. In this paper, different active vehicle chassis control systems and all the available techniques of integration will be discussed. At the beginning, a description of the main techniques used will be presented, then the necessity for combination of these active chassis control systems is studied, followed by a comprehensive review about the state-of-the-art approaches. The purpose of this study is to support automotive manufacturers and suppliers to reach an integrated vehicle chassis control architecture for flexible designs.
Keywords: vehicle stability; handling; ABS; AFS; DYC; ARC; coordination; control; integrated vehicle dynamics; lateral acceleration.
An innovative straddle monorail track switch design for the personal rapid transit
by Chih-Hung Li, Zong Jun Lu
Abstract: An innovative track switch design is proposed for a straddle monorail system that may serve as a personal rapid transit (PRT) system. Previously, a PRT system using the monorail design was thought impossible. Here we introduce onboard guide wheels on the monorail vehicles to be the only movable parts that direct the cars to different paths. Each vehicle activates its own switching mechanism and does not need to wait for the movement of the heavy track beams anymore. Guideways and ground rails accommodated by a switch platform are designed to replace the monorail track beams. To verify the system performance, a model monorail loop and a vehicle were built for testing. Test results and analyses show that the monorail vehicles have enough momentum to traverse the switch area without power, and the required headway for the proposed system is much less than the target of 10 seconds.
Keywords: monorail; PRT; personal rapid transit; track switch; headway.
Prediction and analysis of semi-low-floor bus driver seat vibrations by using the response surface methodology
by Medisetti Jaganmohan Rao, S.P. Sivapirakasam
Abstract: In India, Semi-Low-Floor (SLF) buses were used as shuttles within the city. The main objective of this paper is to develop a quadratic model for prediction of driver seat vibration and analysis of relationship between the seating parameters and driver seat vibrations. Response surface methodology was used to develop the regression model in SLF bus driver comfort. In the development of the predictive model, the seating parameters backrest inclination, horizontal distance from the ABC pedal, foam thickness and speed were considered as model variables, and seat vibration was considered as a response variable. The statistical analysis showed speed was the most significant process parameter to influence seat vibration. Other parameters were found to be insignificant but the interactions among them were found to be significant. Apart from objective analysis, the subjective assessment parameters comfort, visibility and confidence also studied for all the trials. At back-rest inclination 90
Keywords: semi-low-floor bus; DoE; process parameters; weighted acceleration; response surface method; regression model.
Numerical study on whole body vibration evaluation in wheeled and tracked armoured vehicles
by Leonardo Menna Barreto Martinelli, Mário Fedatto Neto, Herbert Martins Gomes
Abstract: The vibration felt by humans is a mechanical agent that can induce discomfort or even produce health damage, depending on its intensity as well as its frequency content. Armoured vehicles are examples of equipment that produce high vibration levels, especially in critical terrain situations, both for the robustness of the suspensions and for the weight and details in the design. There are few articles in the literature evaluating this situation for occupants of these vehicles. The numerical modelling of the vertical dynamics can result in an adequate tool for initial tests and prototypes as well as being able to evaluate vibration levels in terrain situations, speed, occupant positioning, stiffness, and suspension damping. In this work, three armoured vehicles are modelled and compared travelling on an irregular road with bump obstacles in order to evaluate potential high levels of acceleration. Comparisons with international standards are performed with the aim of situating these levels in terms of whole body vibration and impact vibration. Suspension modelling uses a nonlinear Newmark numerical integration method to account suspension nonlinearities present in the tracked vehicle. Discussions and comparisons between each of the vehicle models are presented, along with graphics related to ground reaction force signals and accelerations in the vehicles body and seats. Comfort and health risks graphs are presented and show that there is a gradation regarding comfort levels of the investigated vehicles, with the tracked vehicle indicating high probability of health risk for training routines.
Keywords: vehicle suspension; armoured vehicles; whole body vibration; tracked vehicles; comfort.
Dynamic analysis and design optimisation of a heavy military vehicle
by Burak Can Çiçek, Bülent Acar, S.Kemal İder
Abstract: This paper investigates the dynamic response of a heavy military vehicle that is subjected to a dynamic firing load while it is settled on its outriggers. This dynamic behaviour is one of the major design factors of a launching vehicle. Two different finite element (FE) models are created in ANSYS software to obtain the dynamic behaviour of the launching vehicle. The first model is a detailed finite element model and the second model is a simple and fewer degrees of freedom (DOF) parametric FE model, which is created with the ANSYS Parametric Design Language (APDL) in order to perform the design optimisation by swiftly changing the parameters such as clamp attachment positions on the chassis, outrigger deployment and outrigger case cross-section.
Keywords: heavy military vehicle; dynamic analysis; finite element; design optimisation; outrigger.
Introducing a revised model for determination of rollover threshold speed of buses
by Mohammadreza Sabouri, Arman Hamidi
Abstract: Rollover is critical for intercity bus vehicles, as they often carry a large number of passengers while having a relatively high centre of gravity. Using the same models for determining the Rollover Threshold Speed (RTS) of different types of vehicle may induce some errors, as most of the existing models do not consider several factors such as vehicle type and dimension, vehicle load, turning radius of the axles, and diversion angle of the curve. This study intends to propose a more accurate relationship for determining the rollover speed of the intercity bus vehicles considering the aforementioned factors. Using the revised model, it was shown that when both the radius of the horizontal curve and the diversion angle are small, the diversion angle plays an important role in determining the RTS. The results also suggest that under the assumptions of this study, the RTS for three-axle buses happens at lower speeds compared with two-axle buses.
Keywords: centre of gravity height; curve radius; diversion angle; heavy vehicles; intercity bus; payload; regression model; rollover collisions; RTS; rollover threshold speed; superelevation; traffic accidents; TruckSIM.
Study of tyre-terrain interaction of a military vehicle
by Lucas Sousa, Ricardo Costa Neto
Abstract: Wheeled military vehicles are often used on deformable terrains. In order to understand their performance, a tyre-terrain interaction model is required. The aim of this paper is to present the application of semi-empirical tyre models based on Wong-Reece models in order to investigate the drawbar pull, the resistive torques, the sinkage and the stress distributions beneath each tyre of a six-wheeled military vehicle. An accurate prediction of terrain forces is of interest to engineers and vehicle designers to understand the vehicle performance. Furthermore, a heavy military vehicle can be immobilised owing to particular tyre-terrain properties. In a combat situation, an immobilised vehicle can be dire. The military vehicle was simulated on compact sand and dry sand, when the tyre behaves like a rigid wheel in driven and towed conditions.
Keywords: military vehicles; wheel mechanics; deformable terrains; mobility prediction; Wong-Reece theory.
Experimental-theoretical modelling of the lateral sloshing in rail tankers
by Jose A. Romero Navarrete, Frank Otremba, Alejandro A. Lozano Guzmán
Abstract: The objective of this paper is to describe and to validate a simplified pendulum-analogy model to simulate the interaction of a liquid cargo with its carrying vehicle. For that purpose and scope, a scale-down testing rig is proposed to assess the effect of a sloshing cargo on the level of dynamic forces developed at the wheel-rail interface under a lateral perturbation. The resulting testing rig consists of a rectangular container, spring-supported on a two wheelset bogie having a scale down of 1/10 with respect to a full-size equipment. The chassis and cargo representing the sprung mass, and the wheelset representing the unsprung mass of the resulting mechanical system. The testing rig is used to validate a simple pendulum-based, simplified three degree of freedom mathematical model, of the response of a partially filled container to lateral accelerations. The model comprises a full analogy of the sloshing cargo with the simple pendulum, where the tension in the pendulum bar perturbates the sprung mass. The length of the pendulum is set according to validated methodologies. The resulting mathematical scheme reveals a high correlation with the experimental output, on the order of 99%, while some other performance measures, related to the peak forces and the range of variation of the wheel-rail forces, also show good concordance with the experimental results. Additional simplifications made on the model further suggest that the length of the pendulum, the position of its pivot, and the track width, are the most important parameters influencing
the magnitude of the wheel-rail forces.
Keywords: sloshing; rail tankers; pendulum analogy; experimental modelling; mechanical fatigue.
Bidirectional adaptive cruise control for intelligent vehicles
by Chentong Bian, Guodong Yin, Liwei Xu, Ning Zhang
Abstract: Most of the previously investigated adaptive cruise control methods focused on maintaining a safe front clearance of the host vehicle. Owing to fault or heat fading, the vehicle behind an intelligent vehicle may lose part of braking performance and collide with the intelligent vehicle. Thus the control system of an intelligent vehicle should simultaneously maintain the front and rear clearances on such a critical condition, which is seldom discussed before. In this study, a bidirectional adaptive cruise control algorithm is proposed to reduce such collisions. Simulations have been done to confirm the validity of the proposed algorithm. The simulation results show that the proposed algorithm can reduce the collisions caused by the following vehicle with low braking performance, which cannot be resolved by traditional adaptive cruise control. Thus, compared with the traditional adaptive cruise control, the proposed algorithm can improve the safety of intelligent vehicles in collision avoidance.
Keywords: intelligent vehicle; bidirectional adaptive cruise control; collision avoidance; adaptive cruise control.
Experimental and numerical studies on improvement of drag force of a bus model using different spoiler models
by Cihan Bayindirli, Yahya Erkan Akansu, Mehmet Celik
Abstract: The purpose of this paper is to reduce of drag force of a bus model by using four different spoiler models. The tests were carried out at six different Reynolds numbers in the range from 3.8 x 105 to 7.9 x 105. The drag coefficient (CD) of the bus model was determined as 0.633 experimenatally in a wind tunnel and 0.645 numerically in Fluent package program. The first spoiler model which consists of a combination of airfoil and vortex generator mounted at five different locations (L/H) on bus model to improve the drag force. The drag reduction was obtained between the ranges of 12.254.35% in five different L/H rates by using spoiler 1 model. The spoiler 2 model designed which has airfoil shape and maximum drag coefficient was improved 3.34% as experimentally. 23.49% reduction was obtained by using spoiler 3 in L/H = 0.1 and 18.49% reduction by using spoiler 4 in L/H = 0.15. The numerical flow analyses were performed at the same wind tunnel conditions at six free stream velocities for the base model and best results for each spoiler models. The drag coefficients of best models were reduced 11.48% and 8.59%, 15.90% and 19.05% respectively in Fluent
Keywords: bus model; drag coefficient; wind tunnel; CFD; aerodynamic; spoiler.
Using a mobile app to estimate whole-body vibration and seat isolation performance in surface mining
by Alan G. Mayton, Brian Y. Kim
Abstract: The study objectives were twofold: 1) determine whether the whole-body vibration application (WBV app) may effectively serve as a simple tool for monitoring whole-body vibration exposure; 2) assess when the vehicle seat may need adjustment, repair, or replacement. Data were collected on 17 mobile mining vehicles and equipment at six surface operations. Comparing the WBV app to the Siemens/LMS reference system showed excellent correlation (r = 0.998 and 0.987, respectively), for frequency-weighted-root-mean-square acceleration (aw) and vibration dose value (VDV) normalised to an 8-hr shift. Seat performance, using the mobile app, showed greater variation, yet high positive correlations (r = 0.896 and 0.936) for the aw and VDV computational methods, respectively. Hence, the WBV app demonstrates potential as a low-cost instrument to measure WBV exposures for mobile equipment operators and the capability to estimate seat performance or seat effective amplitude transmissibility (SEAT) when used on two iPod Touch devices.
Keywords: whole-body vibration; mobile iPod app; surface mining; haul trucks; loaders; dozers.
Performance comparison of MD523 and SF400 bogie when passing through different turnouts
by Mahdi Naseritaheri, Shahin Yousefi, Majid Shahravi
Abstract: In recent years, the study of the dynamic behaviour of the high speed train has been taken into account when passing through the turnout. Some of these studies include examining wheel and rail dynamics when crossing the turnout nose and extracting the wheel's contact forces. The dynamical behaviour of passenger high-speed bogies during passage through the turnout is one of the most important factors in the safety of the vehicle. By increasing the speed of wagons when passing through the turnout, safety parameter and wheelset forces should be considered. The statistics have shown that 40% of derailment has taken place due to the inside of the turnout or the defect of the turnout. The purpose of this paper is to study and analyse the dynamics parameters of passenger wagon and safety of a bogie, such as the derailment and the forces of the wheelset when passing through the turnout with different turnout rail profiles, because the type of turnout rail profile and geometry of turnout affect dynamic performance of bogie. In order to investigate this, the simulation of a wagon in a multi-mass dynamic (MBS) UM software has been used on turnouts with different rail profiles and radius of turnout. As the results show, the geometric features of the turnout, such as its radius and turnout rail profile, have greatly influenced the dynamics of the wagon.
Keywords: turnout; derailment coefficient; high speed bogie; dynamic forces; turnout geometrical specification.
Investigating the effects of off-road vehicles on soil compaction using FEA-SPH simulation
by Fatemeh Gheshlaghi, Aref Mardani, Arash Mohebbi
Abstract: The study of terrain-tyre interaction using simulation methods allows for accurate prediction of parameters, such as soil density and rut depth, that are either time-consuming and expensive or inaccessible with experimental methods. This research focuses to predict and evaluate the soil compaction after off-road tyre traffic in different vertical loads on the tyre. Soil-tyre interaction is simulated using the Smoothed-Particle Hydrodynamics-Finite Element Analysis (SPH-FEA) techniques in Pam-crash software. In order to evaluate the simulation model, tests were conducted using a single-wheel tester in soil storage with different numbers of the pass and various loads. Soil density and rut depth were measured and compared with the simulation data. The results indicate that the tests and simulation data are in good agreement with the coefficient of determination of 0.94. The tyre with higher pass number makes greater rut depth and consequent greater soil density. The intensity of soil compaction due to vehicle weight is discussed in the results.
Keywords: tyre-soil interaction modelling; rut depth; soil density; finite element analysis; smoothed-particle hydrodynamics; single-wheel tester.
Vibration analysis of half rail vehicle model with ten degrees of freedom based on mechanical-electrical analogy theory
by Fatih Pehlivan, Ismail Esen, Cihan Mizrak
Abstract: The aim of this paper is to show that vibrations of ten degrees of freedom (10 DOF) half rail vehicle models obtained by both mechanical mechanism and equivalent electrical circuit are identical. Firstly, the system was modelled and then a free body diagram was formed. Afterwards, motion equations of the system were determined using Lagranges method. The mechanical circuit was constructed using force equations and its equivalent electrical circuit was obtained using the Kirchoff current law (KCL) and force-flow similarity. Then, a schema was formed by means of MATLAB Simulink to analyse the vibrations of the rail vehicle model. To make simulations, the speed of the rail vehicle model was selected as 400 km/h. As input, track irregularities in American Railway Standard and non-random irregularities were applied to the all wheels separately. As a conclusion, it was observed that the signals taken by both the mechanical mechanism and its equivalent electrical circuit appeared similar, and the vibration analysis of a complex mechanical system can be modelled not only mechanically but also electrically.
Keywords: mechanical-electrical analogy; half rail vehicle; vehicle vibration; modelling; simulation.
Dynamic analysis of gun control system of main battle tank
by Jitesh Shukla
Abstract: The primary aim of the military tank is to hit on the target efficiently in moving condition on off-track. There are many elements that are responsible for imbalance and loss of accuracy in firing. The battle tank is an assembly of the suspension system, mobility drives of guns such as elevation drive and azimuth drive, ballistic system, firing system, etc. These systems are mainly responsible for disturbance in stability of main gun. The track used for the battle tank also plays a major role in vibrations. Hence, the stability of the gun is possible only when vibrations caused by mobility drives get reduced. Hence, the elevation drive (electrically driven) of weapon control system for 5 degrees of freedom is mathematically developed. Turret rotation is responsible to govern an azimuth drive and is integrated with an elevation math model. A mathematical model of the weapon control system is also modelled in Matlab/Simulink environment. Various weapon drives are coupled, using a collective framework of cantilever beams to develop the gun model. Weapon dynamics of a tank that has 14 station platforms is mathematically modelled in the Simulink environment. The passive dynamic responses of the main gun can be observed by these mathematical models. The integration of the weapon dynamics model would provide the platform to implement the actual control, which would responsible to stabilise the WCS when the tank is cruising off-track. This improves the first-round target hitting probability of the tank. The responses that are observed in the Simulink environment are validated by a model developed in ADAMS.
Keywords: weapon control system; gun control system; battle tank; elevation mechanism; azimuth mechanism; suspension and ride dynamics.
Identification of railway track quality and safety through the dynamic inertial response of railway carbody and truck
by Roberto Spinola Barbosa
Abstract: An extended version of the inertial measuring system installed in the carbody and trucks is used to evaluate the railway track quality and safety, observed from the vehicle dynamic performance point of view. The system measures the dynamic movements of the carbody and is extended to observe also the truck attitude and suspension torsion due to irregular track geometry. The values measured are used in an inertial navigation algorithm with a Kalman filter to identify the full vehicle attitude, including angular positions and accelerations. System equations for the inverse carbody and truck dynamic problem, augmented with the suspension torsion equation, is solved to directly estimate the wheels' driving forces that are directly correlated with the vehicle safety. A dimensionless safety index (SI) is proposed to evaluate track quality and safety. Values obtained are used to quantify track harmful locations. The results of a test campaign, travelling on the irregular track in a conventional train, identified the full vehicle and trucks attitude and the suspension torsion angular movement. The SI and the location of the potentially most hazardous region for track maintenance purposes were identified. Good correlation between the SI and measured track geometry is observed, hence this method is a promising technique.
Keywords: dynamic; safety; vehicle; railway; track.
A modified Odenthal rollover index algorithm for tractor-semitrailer using steering and vehicle speed inputs
by M. Hafiz Harun, Khisbullah Hudha, Pakharuddin Mohd Samin, Saiful Anuar Abu Bakar, Amer Noor Hafizah, Abd Kadir Zulkiffli
Abstract: One of the main factors that cause tractor-semitrailer accidents is vehicle rollover instability. Owing to the size of the vehicle, any accident will significantly affect life, property damage and the tractor-semitrailers components as well as the surrounding environment. Therefore, an early warning indicator of an impending vehicle rollover is essential, especially to the tractor-semitrailer driver in order to control the vehicle and eventually avoid an accident. In this study, a rollover index algorithm is proposed by integrating the modified Odenthal rollover index algorithm with driver steering and vehicle speed inputs instead of lateral acceleration. The modified Odenthal rollover index algorithm performance is evaluated by conducting experiments involving the step-steering manoeuvres, subjected to various speeds and load conditions, in the TruckSim driving simulator and MATLAB/Simulink software. It is observed from the results that the modified Odenthal rollover index algorithm produces 12.4% faster time-to-warn than the Odenthal rollover index for the driver and offers adequate time-to-respond to initiate the corrective actions. Thus, the modified Odenthal rollover index algorithm creates a better early warning system and can prevent rollover accident significantly.
Keywords: tractor-semitrailer; rollover index; time-to-warn; time-to-respond; step-steering manoeuvre.
Optimised coordinated chassis stability control using fuzzy genetic algorithm
by Amro Elhefnawy, Hossam Ragheb, Alhossein Sharaf, Shawky Hegazy
Abstract: Owing to proficient constraints of distinct vehicle subsystems, numerous individual active control systems are optimised individually in specific handling areas. Consequently, there is no single system which can be operative over the entire range of vehicle stability and handling. In this study, an optimised coordinated control system comprising two controllers, namely Direct Yaw Control (DYC) and Active Front Steering (AFS) has been developed based on Fuzzy Logic Control (FLC) in order to boost vehicle handling, cornering stability, and rollover anticipation. Moreover, a Genetic Algorithm (GA) has been customised to optimise the proposed coordinated control system in two phases. Initially, optimising the fuzzy logic controller for both DYC and AFS by linear scaling of the inputs and outputs of each controller, and also by the weight of each rule. Lastly, a genetic tuning of the coordination function has been executed. Different benchmark test manoeuvres have been carried out at different driving speeds and road conditions to scrutinise the proposed coordinated control effectiveness. Simulation results shows a significant enhancement in vehicle stability has been accomplished.
Keywords: direct yaw control; active front steering; fuzzy logic control; genetic algorithm; coordinated control.
Determination of tyre-ground interaction parameters through image processing in Matlab
by Petru Rosca, Marius-Ionut Marmureanu, Tudor-Viorel Tiganescu, Catalin-Mihai Pirvulescu, Irina-Maria Bindac, Calin Doru
Abstract: The tyre-ground interaction represents a topic highly debated but still many aspects are to be further studied and analysed. In this context, one representative parameter is the wheel ground pressure its influence is associated with the design of rigid pavements, with the restraints imposed by the aircraft cargo capacity and with the vehicle off-road capabilities, at least. In fact, the wheel ground pressure represents the ratio between wheel load and contact patch area. If the weight of a vehicle and its distribution on wheels can be easily measured, the contact patch area quantification requires either sophisticated and expensive to determine, or the compromise of obtaining inaccurate results by using more or less adequate predictive formulas. This paper presents a modern and efficient method, through image processing in Matlab, which can be used in order to accurately determine the contact area and other related parameter such as mobility area, the maximum contact length, and the maximum contact width. It also proposes new prediction equations for the contact area and for the mobility area based on experimental data related to Continental 14.00 R20 tyre type. The applicability on the tyre-ground interaction should be seen as a particular case, at least for the image processing method, its helpfulness being noted in many areas, as well topography, tribology, and medicine.
Keywords: tyre; pressure; area; image; Matlab.
Investigation and analysis of hydraulic cylinder cushioning of excavator
by Govindarajalu Venkatesan, Sadagopan Palaniswamy
Abstract: Hydraulic cylinders are the linear actuators used in applications such as industrial, agricultural and construction equipment like excavators. The backhoe of an excavator can dig with enormous force and its movements are carried out by the hydraulic system. The piston movement, from rear to front end, swings the backhoe in seconds and if it is not slowed down at the end, the swing stops suddenly resulting in metal to metal contact causing jerk, vibration and bounce due to inertia effect. This phenomenon leads to failure of seals and other components causing higher maintenance cost. The size and profile of the cushion nose plays an important role in slowing down the piston movement. Hence in this work, an attempt is made to investigate the cushioning effect by changing the size and profiles of the cushion nose based on DFMA and to analyse the pressure variation with respect to piston movement using CFD and the results are presented. In addition, from the results, analysis is carried out using DOE to find the most significant factor that affect the back pressure and smooth transition of pressure. It is found that the cushion nose with curved internal profile produced better results than the existing taper design cushion nose profile and other profile variations.
Keywords: hydraulic cylinder; cushioning; excavator; backhoe; cylinder cushion; cushion nose profile; deceleration; actuator; computational fluid dynamics; DFMA; DOE.
A review of fuel cell technology for commercial vehicle applications
by Tommi Jokela, Bo Gao, Bill Kim, Matthias Wellers, Jun Peng
Abstract: Commercial vehicles contribute a significant and increasing portion of road transport greenhouse gases, which is leading to regulators introducing CO2 limits for these vehicles. The demanding energy storage requirements of many commercial vehicle applications are extremely difficult to meet for pure battery electric vehicles due to the limited energy density of batteries whereas hybrid commercial vehicles that include combustion engines can only provide limited amounts of emission reductions. Fuel cells appear to be the only viable propulsion technology that is able to meet commercial vehicle application requirements with zero local greenhouse gas emissions. The particular strength of fuel cell vehicles compared to battery electric vehicles is their high energy density, making them particularly suitable for commercial vehicle applications that often require long driving ranges. Since almost all fuel cell vehicles also contain a high voltage battery, some additional complexity is introduced since the hybrid energy storage system must be sized and controlled appropriately. An understanding of the strengths and weaknesses of each system is therefore essential in fuel cell vehicle design. The aim of this technology review is thus to provide an overview of fuel cell technologies in commercial vehicle applications including assessments of alternative powertrain and fuel cell types, advantages and disadvantages of fuel cell and battery systems and the implications of these on the powertrain sizing as well as control considerations of fuel cell vehicles.
Keywords: fuel cell; commercial vehicles; powertrain; energy management strategy.
Development of an integrated active yaw controller on soft terrain
by Hossam Ragheb
Abstract: Off-road vehicle maneuverability on soft terrain is strongly affected by the tyre-soil interaction characteristics. Remarkable enhancements in active vehicle safety systems depend on different control systems aiming to enhance off-road vehicle mobility. In this paper, an integrated active yaw control system, Anti-Lock Braking System (ABS) and Traction Control System (TCS), for an (8x8) multi-wheeled combat vehicle operating on soft terrain is developed. A TruckSim-MATLAB/Simulink vehicle model was developed to verify the developed integrated control system on soft soil. The presented integrated control system revealed an enhancement in vehicle directional stability and traction performance. Besides, it should be mentioned that the soil type has a great effect on controller efficiency as it is limiting the applied torque by the developed controller.
Keywords: off-road; mobility; active yaw control; anti-lock braking system; traction control system; TruckSim; MATLAB/Simulink; multi-wheeled vehicles; soft soil.
Developing an analytical model for prediction of tyre rolling resistance on moist soils
by Fatemeh Gheshlaghi, Aref Mardani, Arash Mohebbi, Hamid Taghavifar
Abstract: This paper presents a Finite Element Analysis Smoothed Particle Hydrodynamics (FEA-SPH) technique to predict the rolling resistance of an agricultural tyre over moist soils. Firstly, dry clay-loam soil is modelled using hydrodynamic elastic-plastic materials and the water behaviour is captured using the Murnaghan equation of state. Then, to simulate moist soil, water layers are added to the dry soil surface. Soil calibration is performed based on experimental data using a bevameter and through the direct shear tests under similar operating conditions. A free-rolling Bias-ply tyre (size 8.25-16) employed for the experiments was modelled using the FEA method. The interface contact between tyre and soil is described based on a node-symmetric node-to-segment contact with edge treatment. The obtained simulation results for rolling resistance account for different levels of soil moisture, traffic and vertical load. Finally, the proposed model is validated using experimental data obtained from a single-wheel tester in the controlled test condition.
Keywords: rolling resistance; smoothed-particle hydrodynamic; finite element analysis; moist soil; vertical load; soil bin.
Fractional order state feedback control for improved lateral stability for tractor-trailers in platooning
by Rasheed Abdulkader, Roy McCann
Abstract: This paper develops an improved tractor-trailer platooning operation for an evasive highway manoeuvre situation by implementing a fractional order state feedback control method. This increases the lateral stability of commercial heavy vehicle platoons and thereby improves energy savings and safety. The control method is developed based on a nonlinear model for a tractor-trailer in platooning formations. A method for analysing heavy vehicle dynamics is presented. To validate the proposed control algorithm, the complete nonlinear system is evaluated in MATLAB/Simulink to account for the interaction of truck dynamics during the platooning operation. Simulation results with varying the truck speed and the trailer load demonstrate the robustness of the proposed fractional order state feedback control scheme for an evasive manoeuvre scenario. Thus the proposed control scheme is compared with a professional driver for an emergency highway lane manoeuvre. Overall results confirm that the proposed controller improves tractor-trailer response time as compared with a professional truck driver along with increased energy savings and reduced fuel consumption during the platooning operation of the tractor-trailer.
Keywords: lateral stability; active front steering; platooning; fractional order control; tractor-trailer dynamics.
Liquid cargo effect on load transfer under orthogonal accelerations
by Jose A. Romero Navarrete, Frank Otremba, Alejandro A. Lozano-Guzman
Abstract: A methodology is proposed for the experimental analysis of the liquid cargo effect under combined orthogonal accelerations. When simultaneously subjecting the vehicle-cargo system to longitudinal and lateral accelerations, the vehicle is set obliquely on a tilt table. The experimental outputs suggest that there is a significant effect of the liquid cargo on the lateral load transfer ratio (LTR), of the order of 20%, which is attributable to the resulting shifting of the liquid cargo
Keywords: sloshing; liquid cargo; cargo shifting; lateral load transfer; braking in a turn manoeuvre.
An investigation into the ride comfort of buses using an air suspension system
by Vu Tan, Truong Hung, Sename Olivier
Abstract: The paper focuses on the ride comfort criteria of a two-axle bus using an air suspension system. First of all, based on the Gensys model, a nonlinear model of an air spring element linked to an auxiliary air tank is investigated. The parameters of the air spring model are determined through real experiments in both static and dynamic load modes, in order to ensure that the error between the theoretical simulation model and the real experimental data is less than 8%. Then, a full bus model using the dependent suspension system takes into account the driver model mentioned in two cases: 1) using air suspension and 2) using leaf suspension. Simulation results in the time domain with different motion states show that the ride comfort of the bus using air suspension system is improved by about 20%, when compared with the bus using the leaf suspension system. Meanwhile, the road holding criterion is maintained, because the interaction force between the wheels and the road of the bus using air suspension system is improved to a small extent.
Keywords: vehicle dynamics; air suspension system; air spring; ride comfort; road holding; buses.
Study on super-wheelbase preview controller/algorithm for internet of vehicles suspension system used in a heavy vehicle fleet
by Ce Yuan, Jiang Liu, Xilong Zhang, Bilong Liu, Yushun Wang
Abstract: Most truck fleet transportations show typical repetitive features in vehicle models, routes and cargos. So the Internet of Vehicles (IoV) theory could be easily introduced into the active control for truck suspensions. We establish a communication network structure in which paired vehicles are basic elements, and the geographic information system is treated as a detection auxiliary. The new design reduces the overall communication demand for suspension control data. Based on this simplified IoV system, a new super-wheelbase preview control method is proposed. The optimal vehicle distance between paired trucks is calculated by the particle swarm optimisation. The traditional wheelbase preview algorithm is improved by using two equivalent parameters. The rear truck shows better comprehensive suspension performances than the front one. Finally, we perform a simple objective optimisation in the truck pairs sequence. The convergence results show that, with the help of the IoV suspension system, the sixth and after trucks can get the minimised body acceleration in the fleet's first loop.
Keywords: suspension; IoV; super-wheelbase preview; particle swarm optimisation.
Dynamic stability analysis of a high speed diesel engine turbocharger subjected to aerodynamic loads and engine-induced vibration
by Ali Alsaeed, Salem Bashmal
Abstract: The dynamic behaviour of a high-speed turbocharger supported on floating-ring bearings is investigated under the effect of engine-induced vibrations and aerodynamic loads. A finite-element model is developed for the turbocharger to predict the nonlinear transient response while engine excitations are simulated as time-varying force functions on the rotor bearings. Damping and stiffness parameters of the floating-ring bearings are estimated by solving the 2-D Reynolds equation. The engine-induced excitations are combined with compressor radial aerodynamic forces to obtain the total response numerically. Modified non-circular volute theory is used to calculate radial thrust loads due to aerodynamic effects. The numerical predictions agree with the experimental observations of a fully-loaded turbocharger that show no significant second harmonic frequency amplitudes of the engine frequency. However, the engine frequencies are at comparable amplitudes with the Sub High and 1X amplitudes at higher speeds, where the radial aerodynamic loads are not significant (no-load). The results of the present work indicate that, in the subsynchronous region, some amplitudes at the engine-excitation frequency are also observed at the second harmonic for high speeds. Moreover, the dynamic stability of the turbocharger is significantly influenced by the variation in the magnitude of the engine-induced vibration. The numerical predictions are consistent with the previous experimental tests for a typical turbocharger.
Keywords: turbocharger; stability; transient response; aerodynamic forces; vibrations.
Special Issue on: Recent Advances in Active Safety Control Systems for Commercial Vehicles
Investigating the active suspension performance using 2/ robust controller combined with particle swarm optimisation
by Hamid Taghavifar, Leyla Tagahvifar, Aref Mardani
Abstract: A robust controller design technique for vehicle active suspension systems is investigated, which takes into consideration the road disturbance as the uncertainty of system parameters. The design of the robust controller is considered as a dynamic optimisation problem, and two artificial intelligence approaches of genetic algorithm and particle swarm optimization are adopted to find the optimum amounts of weighted mixture of H∞/H2. The cost function of the robust controller is designed based on the norms of the weighted mixture of H∞/H2 for a plant with a definite feedback gain and coefficient of norm of infinity that varies in the range between 0 and 1 representing absolute H2 and H∞, respectively. Particle swarm optimisation showed a competitive convergence to the global minimum of 127 in the shortest time and was selected as the best performing technique. The adopted system improved the system response in terms of sprung mass acceleration, suspension deflection and unsprung mass displacement. The obtained results from the simulations further confirm the superiority of the proposed system relative to the classical passive suspension, and signify the robustness of the active controller design.
Keywords: active suspension; robust control; suspension deflection; particle swarm optimisation.
Special Issue on: Heavy Vehicle Systems in Real-Time Applications
Design and SAM analysis of reconfigurable four-legged mechanism using single degree of freedom
by A. Krishnaraju, Abdul Zubar
Abstract: A number of examples of walking equipment integrated with heavy vehicle systems and robots have been conceived, measured and built in the last 25 years to occupy modern fields of application. Compared with wheeled equipment, legged and walking machines show the advantage that they can act in highly unstructured terrain without having to prepare this terrain in advance by streets or rails. Legged robots cross obstacles more easily and depend upon the environmental situations. In this paper, a proposed kinematic four-legged model design is made by linkages using a single degree of freedom (DOF), then the paper performs the modelling and kinematic analysis of a reconfigurable four-legged walking mechanism driven by manual or a single actuator using SAM analyser software. A four-bar walking mechanism can be observed by different link lengths in path movements, velocity, and acceleration. In particular, a suitable model of the leg design and also kinematic analysis has been analysed. One of the most important concepts of this research is the desired simplicity of the four-legged walking mechanism.
Keywords: degrees of freedom; integrated system; heavy vehicle system; path trajectory; SAM analyser; simulation; walking equipment; stability.
Special Issue on: Emerging Technologies for Traffic and Transportation Science
Optimal design of die casting process parameters of A713 cast alloy with grain refinement by using a genetic algorithm approach for automobile industries
by Rosang Pongen, Anil Kumar Birru, Parthiban P
Abstract: Aluminium die castings cover a major domain in the field of production, which mainly involves automobile and aerospace areas, owing to its high strength to weight ratio and the high industrial demand for aluminium alloys. Aluminium die castings are associated with many casting defects, which are influenced by many process parameters and influence the final mechanical properties of the die cast aluminium alloy. The density, which gives an idea about the variation of porosity of the die cast parts, is considered to play a vital role in the quality of the alloy. Since die casting is governed by many process parameters and often results in castings with poor properties, it is necessary to know the nature of the output responses before manufacturing. A genetic algorithm (GA) optimal prediction model may help in predicting the optimal output responses before the actual production in die casting. In this present research, a GA approach for optimising the theoretical and experimental density of an A713 alloy with Al-3.5 Ti-1.5C and Al-3Cobalt as grain refiners is carried out. The selected die casting process parameters are molten metal temperature, Al-3.5, Ti-1.5C, and Al-3Cobalt (wt. %), die temperature and injection pressure. Theoretical and experimental densities are considered as outputs for the GA modelling. The GA was run for two cases, one case for theoretical density optimal prediction modelling and other case for experimental density optimal prediction modelling. The model for optimally predicting the theoretical and experimental density of A713 alloy with grain refiners has been established using the GA.
Keywords: A713 alloy; die casting; optimisation; genetic algorithm; experimental density; theoretical density.