Vehicle Speed Conditions Research Articles

Degradation-considering adaptive equivalent consumption minimization strategy for fuel cell electric vehicles

In order to improve the economy and durability of fuel cell vehicle, a degradation-considering adaptive equivalent consumption minimization strategy (D-ECMS) was proposed for fuel cell/lithium battery hybrid power system. Aiming at enhancing the adaptability of the equivalent consumption minimum strategy, four different vehicle speed conditions were considered including low speed, medium speed, high speed, and ultra-high speed. Particle swarm optimization (PSO) algorithm was used to optimize the penalty factor under different vehicle speed conditions, and BP neural network was used to identify real-time conditions to form an adaptive equivalent consumption minimum strategy (A-ECMS). The voltage decay model of the fuel cell was established according to the voltage decay rate of the fuel cell under the three adverse conditions of idle speed, high power and dynamic load cycle. The voltage decay of the fuel cell was transformed to hydrogen consumption in the cost function of the A-ECMS strategy to obtain the D-ECMS considering durability degradation. The simulation and the hardware-in-the-loop (HIL) test based on the dSPACE real-time platform was carried out. The results show that: compared with A-ECMS, the hydrogen consumption of the D-ECMS increased by 5.2%, 9.7%, 10.2%, and 0.2% respectively under WLTC, NEDC, UDDS, and HWFET cycles. However, D-ECMS can reduce the voltage decay by 38.3%, 59.7%, 35.2%, and 26% under the above four test conditions, and their total comprehensive cost loss is reduced by 8.7%, 6.7%, 9.6%, and 6.3% respectively. As result, the D-ECMS can reduces the voltage attenuation of fuel cells and improve the durability of fuel cells significantly with a small hydrogen consumption increase,which can reduce the operating cost of fuel cells finally. Furthermore, the average error between the results of HIL test and offline simulation results is less than 5%, which validates the adaptability and real-time application feasibility of D-ECMS.

Four-wheel steering vehicle trajectory tracking control based on PSO optimized MPC

In order to address the difficulty induced by controller parameter uncertainty in trajectory tracking control of four-wheel steering vehicles(4WS), a trajectory tracking control method for unmanned vehicles based on particle swarm optimization (PSO) is proposed to improve the robustness of the controller. The approach involves the use of model predictive control (MPC) for implementing trajectory tracking control for the unmanned vehicle. Iterative optimization is conducted by utilizing the integral time absolute error (ITAE) as the objective function, which involves multiplying the time integral of lateral deviation and yaw rate deviation. This process ultimately determines the optimized MPC weight matrix parameters. Co-simulation using CarSim/Simulink reveals a remarkable reduction of 46.1% in the maximum longitudinal error, and the optimization proves effective across various vehicle speed conditions. Experimental results validate the effectiveness of the proposed control strategy, with the 4WS control strategy yielding a maximum longitudinal error of 0.28 meters, affirming that the overall controller design successfully accomplishes its intended objectives.

Research on model predictive trajectory tracking control based on particle swarm optimization

Abstract This paper focuses on the challenges of low trajectory tracking accuracy in intelligent vehicles caused by different road adhesion coefficients and vehicle speed conditions, aiming to address these challenges with an improved Model Predictive Control (MPC) algorithm. Firstly, a model encompassing vehicle dynamics featuring two degrees of freedom has been formulated, along with a corresponding model to track trajectory errors. Secondly, a Model Predictive Control (MPC) algorithm is designed with trajectory tracking accuracy and control increment as the objective functions. Additionally, incorporating a Particle Swarm Optimization (PSO) algorithm with MPC allows for the dynamic computation of the optimal prediction horizon size. Afterward, a unified simulation model is assembled, employing both CarSim and MATLAB/Simulink, to conduct dual-lane trajectory tracking simulation analysis under diverse road adhesion and vehicle speed conditions. The efficacy of the proposed control algorithms is validated through this process.

Driving adaptability of highway steel-concrete composite beam bridge with multiple damages: theory, technology and practice

ABSTRACT To enhance the post-disaster highway driving speed evaluation system for steel-concrete composite beam bridge (SCCBB), a human-vehicle-bridge coupled driving adaptability analysis method is proposed. This method integrates considerations of both driving safety and comfort. Numerical simulation is employed to utilize a damaged SCCBB as the engineering context for studying vehicle rollover safety, vibration acceleration limits, and driving comfort. The analysis considers various vehicle types, including sedan cars, mini vans, motor buses, and trucks, resulting in recommended speed limits for each category. The study reveals that trucks demonstrate lower susceptibility to rollover accidents compared to sedan cars, mini vans, and motor buses under constant damage grade and vehicle speed conditions. However, increased damage grade and road surface roughness elevate rollover risks and diminish driver comfort. To ensure smooth post-disaster traffic flow on SCCBB and maintain acceptable driving comfort and speed levels, it is recommended to enforce speed limits: below 60 km/h for sedan cars, below 40 km/h for mini vans and motor buses, and below 80 km/h for trucks. The primary aim of this study is to provide technical guidance for the safe operation and maintenance of post-disaster SCCBB.

Analyzing the effect of vehicle speed and class of random road profile on a 4-axle truck vehicle vibration

The vehicle will generate vibration due to the impact of road surface, wind, steering, accelerating, braking...as it moves on road surfaces. These vibrations directly affect people and goods. A 14 DOF full vehicle dynamic model of the 4-axle truck vehicle with the torsion of the chassis and the “Walking Beam” tandem suspension is developed to analyze the effect of vehicle speed and a class of random road profile conditions on the vibration of the 4-axle truck vehicle which is developed based on Newton Euler equations and solved via Matlab/Simulink software. The study results have shown that the road surface and vehicle speed conditions have a great effect on vehicle vibrations. In addition, the results of this study could provide useful analysis results for proposing solutions to optimize the structure of the suspension system to improve the ride comfort of the vehicle and reduce the dynamic load of multi-axle truck vehicles.

Experimental investigation on the R1234yf air conditioning system with a battery cooling loop under realistic conditions of electric vehicles

The air-conditioning system of an electrical vehicle (EV) with a cooling loop for battery was experimentally investigated at medium to high load conditions, using R1234yf as refrigerant. Optimal filling rates of R1234yf and R134a were first determined as 975 g with the battery cooling loop closed. Then, the system performance regarding the two refrigerants with optimal charges was compared with various chiller thermal loads at maximum cabin cooling capacity condition as well as nine high load conditions. It was found that using R1234yf as the alternative of R134a, the HVAC cooling capacity, the power consumption of the compressor and the coefficient of performance (COP) decreased by 23.6%, 10.5%, and 8.1%, respectively, at maximum cooling capacity condition with a chiller load of 1.5 kW. At high load conditions with various chiller thermal loads, the reductions of HVAC cooling capacity and power consumption were 8.2%–29.8% and 3.2%–19%, respectively, resulting in a decrease in COP of 1%–16.3%. Thirdly, it was presented that, for R1234yf, at high vehicle speed conditions with the TXVs as original setting, the outlet air temperature of the HVAC box increased about 2.4°C, with the power consumption increased by 17.3%, if the chiller thermal load was increased from 0 to 2.5 kW. Other main conclusion included that, at idle condition, for the R1234yf system with the chiller loop on, the outlet temperature of the HVAC box and COP decreased by 2.7°C and 37.1%, respectively, when the compressor speed increased from 4000 to 7000 rpm.

Collection of different types of milk with multi-tank tankers under uncertainty: a real case study

The milk collection problem can be basically defined as the daily collection of raw milk from different points (farms/milk collection centers) and delivering it to a dairy facility. To enhance final dairy quality, it is important to use the appropriate quality of raw milk for each dairy product. However, collecting different types of milk comes with additional logistics costs which significantly increase in an uncertain environment. In this study, we, therefore, propose a novel mathematical model for the collection of different types of milk from producers by multi-tank tankers with split deliveries, uncertain demand, service time and vehicle speed conditions. A real-life case study from a dairy company is solved under different risk assessment scenarios. Indeed, several brand-new benchmark instances for the core problem are presented and solved by utilizing an efficient heuristics approach called enhanced iterative local search. All the case study results show that considering the uncertainty is very critical for designing efficient collection networks. The findings of the study indicate that logistics decision makers should design their collection networks with low, but non-zero, risk levels.

Design, size estimation, and thermodynamic analysis of a realizable organic Rankine cycle system for waste heat recovery in commercial truck engines

The application of the ORC system for WHR in truck engines is a promising tool that minimizes the rate of CO2 released by the automobile industry and reduces specific fuel consumption by the sector. This article describes the development of a high-performance energy reuse module and size estimation for application in highway truck engines. The concept was performed on GT-Suite (vs. 2019) platform using R245fa as working fluid, and the evaluation of the module size was done using details from supplier specifications. Interestingly, the ORC system simulations were all performed at vehicle speeds of 66–119 km/hr to achieve realizable vehicle speed conditions. The modelling accomplished 2.99 kW of net power output, 3.27% BSFC improvement, and 6.36% ORC system efficiency, respectively. The ORC module's total estimated weight is approximately 100 kg, roughly giving a 32.3 kg/kW weight-to-power ratio.

Performance Analysis of DDM Method to Reduce The Doppler Effect on Vehicular

VANET is an innovation that supports vehicle to vehicle and vehicle to infrastructure communication. The main application of VANET technology is to realize better and safer traffic management. However, due to the high mobility of the vehicle, this technology causes the Doppler effect, when the spectral signal enlarges in the OFDM system. The Doppler effect occurs due to the influence of the use of Rayleigh fading vehicle-to-vehicle channels on the VANET environment and the effect of changing channel movement conditions causing time-varying channels. It also triggers the spread of Doppler to be larger than the symbol duration. This certainly can disrupt the orthogonality of the OFDM system which is the basis of VANET communication. The effect is the occurrence of ICI (inter-carrier-interference) causing the performance of OFDM to decrease. This research proposes the Direct Development Method (DDM) scheme, a technique to compensate for the Doppler effect which is different from the general scheme. In this study, the scheme used is to focus the corrector on the data frame before sending it. The simulation is carried out by testing the modulation which refers to the IEEE 802.11p standard with 4 different vehicle speed conditions namely 24, 64, 144, and 294 km/h. Analysis of the performance of the application of the DDM scheme on modulation based on the effect of the speed provided gives better results compared to the modulation performance without the compensation of the Doppler (Non-DDM) or conventional effects on the SNR requirement side to achieve the BER 10Ȓ3 target.

Computational fluid dynamic analysis of an unmanned amphibious aerial vehicle for drag reduction

PurposeThe aim of this article is to minimize the drag of an unmanned amphibious aerial vehicle (UAAV) and enhancing the endurance.Design/methodology/approachVarious surface geometrical profiles such as rectangular, semicircular groove, razor blade and V-groove riblets are incorporated into the UAAV, and computational fluid dynamic (CFD) analysis is performed for various angles of attack at diverse vehicle speed conditions to estimate the coefficient of drag considering k–e turbulence model. Comparative evaluation between riblet and blunt body shape methodology is performed. Wind tunnel experiments are conducted to validate the flow characteristics around the UAAV.FindingsIt is observed that V-groove riblet method produced minimal drag in comparison with other profiles. The pressure distributions around UAAV for various geometrical profiles suggested that V-groove profile has achieved minimal vortex region, flow separation and turbulent boundary layer near to the outer profile.Originality/valueThe CFD analysis of UAAV for various riblet configurations and validation with wind tunnel smoke test confirms that UAAV with V-groove riblet provides low drag.

Optimization of a diesel engine calibration for operating with a residual glycerol-derived biofuel

The new European directive for the promotion of renewable energy mandates an increase in the share of advanced and waste-based biofuels in the transport sector. In this study, an advanced glycerol-derived biofuel was used as a component of a ternary blend, denoted as o·bio®. This blend included 27.4 %v/v of fatty acid glycerol formal ester, 69.6 %v/v of fatty acid methyl ester and 3 %v/v of acetals obtained as a by-product of the fatty acid glycerol formal ester production process (which were proved to improve cold-flow properties). Finally, o·bio® was blended with diesel fuel at a content of 20 %v/v. Two operating conditions based on usual driving modes were selected, where the engine calibration could be re-optimized after the change of fuel, corresponding to vehicle velocities of 50 and 70 km/h. Since the main effect of the blend used is to reduce particulate matter emissions, exhaust gas recirculation was increased and injection was delayed, so that the initial benefits in particulate matter emissions could be re-distributed into benefits in both particulate matter and nitrogen oxides (NOx) emissions. From a combined analysis of the particulate matter–NOx trade-off and trying to limit the negative effect of delaying injection on fuel consumption, the final proposal was to set an additional 6% exhaust gas recirculation at 50 km/h and an additional 3% exhaust gas recirculation at 70 km/h, while delaying injection 2 °CA after top dead center at both vehicle operating conditions with respect to the original calibration. The use of the blend along with the optimization of the engine calibration is expected to reduce particulate matter and NOx emissions by around 50% with a vehicle speed condition of 50 km/h and to reduce particulate matter and NOx emissions by around 30% and 40% at 70 km/h with respect to diesel fuel emissions.

Dynamic control of electronic differential in the field weakening region

ABSTRACTA simple and dynamic electronic differential control method for an outer rotor motor driven electric vehicle based on fuzzy gain scheduling of PI gains method is proposed for constant torque and power region operation using brushless direct current (BLDC) machine. The proposed method is quite insensitive to torque fluctuations and transient speed oscillations due to surface mounted permanent magnet (SMPM) BLDC machines constraints in the field weakening region. To improve the dynamics and stability of the electronic differential system and eliminate the skidding of the wheels and reduce the heating of electric machine in the wide speed range operation, a robust control method is developed. Moreover, PI controller gains are updated continuously by fuzzy gain scheduling approach which has phase advance angle, steering angle and measured speed as controller input parameters in order to eliminate the errors caused from the variable road conditions and torque oscillations in the field weakening region. The proposed method is implemented with 2 × 1.5 kW BLDC motor drive controlled by a TMS320F28335 digital signal processor (DSP). The experimental results show that the proposed method exhibits greater stability under various load, road and vehicle speed conditions.

Two-Time-Scale Braking Controller Design With Sliding Mode for Electric Vehicles Over CAN

This paper proposed a braking torque controller via two-time-scale design with a sliding mode for electric vehicles with four in-wheel motors. According to the different changing rates between the vehicle and wheel motion during the braking process, the design of the braking controller is carried out in two steps. In the first step, a nominal braking controller is developed over the slow-time scale without considering the tire-road friction. Then, a tire-road friction observer is adopted in the fast-time scale to recover the performance of the nominal braking controller. Owning to the high nonlinearity and complexity of the braking system, a sliding mode surface is further added in the nominal braking controller to ensure the stability and robustness of the proposed braking controller. A braking supervisor is adopted to enable the proposed braking controller, which is based on the wheel slip as well as vehicle speed condition. And a torque allocation scheme is presented for the coordination between the regenerative braking system and the friction braking system in each wheel. Co-simulation is conducted using MATLAB/Simulink and CarSim. The effectiveness of proposed controller under different braking conditions is fully validated. A delicate controller area network (CAN) bus model is developed via SimEvent, by which the robust performance of proposed braking controller against CAN-induced time-varying delays is also investigated.

Control-Oriented Engine Thermal Model

The optimization of modern internal combustion engines and vehicles led several researchers to investigate the effects of the coolant system on overall efficiency losses. Electric water pumps have been proposed as a solution to decrease the high power consumption that typically affects mechanically-driven water pumps at high engine speed. Furthermore, decoupling the coolant flow from engine speed allows achieving a better warm-up behavior. The coolant system components, however, also impact vehicle efficiency: the radiator area affects the overall aerodynamic drag coefficient, especially for race vehicles and motorcycles.A thermal model can be used to assess the effects of the components characteristics (pump size, efficiency, speed; radiator surface, fan size, etc.) both on the coolant system capability to reach and maintain the target temperature, and the power it requires. The same model-based approach can be used for optimal thermal management, to control the coolant system actuators (electric pump and valves, fan). The paper shows how the thermal behavior of the engine can be represented by means of a concentrated parameters model, taking into account the main coolant system components features. The model has been calibrated on a set of data referring to a high-performance motorcycle engine, including both idling and high vehicle speed conditions. The good agreement of the model output with experimental data both in static and dynamic conditions confirms that the model is able to catch a large part of the phenomena influencing the coolant temperature.

Hierarchical Braking Torque Control of In-Wheel-Motor-Driven Electric Vehicles Over CAN

This paper proposes a hierarchical braking torque control system design over controller area network (CAN) for electric vehicle with four in-wheel motors. Based on nonlinear tyre-road friction estimation, an adaptive braking torque control scheme is devised in the upper level controller to simultaneously regulate the wheel slip ratio for both front and rear wheels. While in the lower-level controller, a frequency-depended braking torque allocator is developed to dynamically distribute the braking torques command from upper level controller into friction braking torque and regenerative braking torque. A braking supervisor is established to enable or disable proposed hierarchical braking controller according to wheel slip ratio as well as vehicle speed condition. To avoid undesired discontinuities in braking torque signal when proposed braking controller is enabled abruptly, an initial value of the estimated tyre-road friction is rescaled additionally. Dedicated CAN bus module is built by using SimEvent toolbox, by which vehicle states as well as control signals can be transmitted and shared. Co-simulation by using MATLAB/Simulink and CarSim is conducted to demonstrate the effectiveness of the proposed hierarchical braking torque controller. Random CAN-induced delays are considered in the braking control process, by which the robustness of the proposed hierarchical braking controller is further verified.

Modeling and Simulation of Linear Two - DOF Vehicle Handling Stability

Based on the theory of vehicle steering dynamics, a model of linear two-DOF vehicle handling stability was established in MATLAB / Simulink environment. Simulation analysis of state variable response such as vehicle yaw velocity and side slip angle was made under different vehicle speed conditions for step-input of front-wheel turning angle. The response curves of the state variables in the time domain are obtained under three vehicle speeds. The results show that the response curve of simulation is in good agreement with the actual situation, which not only verifies correctness of the established vehicle handling stability model, but also provides theoretical basis for subsequent design of handling stability control system.

평행주차를 위한 자동 조향 제어시스템 개발 및 성능평가

This research is conducted to develop an automatic steering system for parallel parking, and the performance of the system was evaluated by parallel parking a conventional vehicle. The automatic steering system consisted of MDPS (motor driven power steering) to control steering, ESC (electronic stability control) to acquire wheel speed, ultrasonic sensors to recognize the parking space, and a controller to communicate and handle data. The parallel parking process using the automatic steering control consisted of parking space recognition, parking path generation, and parking path tracking. The path for parallel parking was generated based on a kinematic model of a conventional vehicle, and a PI controller was used to control the steering angle for path tracking. Parallel parking using the automatic steering control was conducted according to vehicle speed conditions. The results show that the errors on the x-axis and y-axis were below 0.54 m and 0.14 m, respectively, and the error on the steering angle was less than <TEX>$1^{\circ}$</TEX>. Therefore, it is possible to implement parallel parking using an automatic steering control system for conventional vehicles.

Characteristic and Affection Analysis on Air into the Cabin Process Based on Wind Tunnel

The wind tunnel test dating for the cooling module in the vehicle conditions shows that the actual fan rotation is evidently different from the fan in bench test rotation. There is an intake high pressure zone. It is easy to conduct airflow into the cabin, and under the cabin, there is a negative pressure zone. It is easy to conduct airflow outside the cabin. Both of the different pressure zones affect the fan rotation. Air path of the cabin is divided into three different areas. Base on the parameters of CP BIR and-CP, the aerodynamic characteristics of the cabin build the cooling module under the vehicle working conditions. The model can predict the states of the fan working, when the target vehicle speed conditions are met, and it has important application value for the design of intelligent cooling module control system as well.

Road Feel Design for Vehicle Steer-by-Wire System Based on Joystick

In order to solve the problem of road feel feedback of vehicle steer-by-wire (SBW) system based on joystick, a road feel control strategy was established to analyze the road feel theory of traditional steer system, which included return, assist and damp control module. By verifying the computer simulation results with the control strategy from software of CarSim and Matlab/Simulink, it shows that the proposed strategy can effective get road feel in different vehicle speed conditions and could improve the vehicle maneuverability to achieve desired steering feel by different drivers.

Health Risk Evaluation of Whole-body Vibration by ISO 2631-5 and ISO 2631-1 for Operators of Agricultural Tractors and Recreational Vehicles

This paper presents experimental research evaluation of the vibration exposure for the health risk prediction during vehicle operation. The vibration measurements were carried out on a recreational vehicle and two types of agricultural tractors. The vibration levels were measured for different surfaces and vehicle speed conditions. Based on the analysis of the results in the small agricultural tractor operated in the workplace (frameworks), Sed exceeded 0.80 MPa by ISO2631-5:2004, and Av exceeded 0.89 m/s(2) by ISO2631-1:1997. That means that operators driving small agricultural tractors more than 8 h a day have a high probability of adverse health effects. However, the exposure value for the recreational vehicle had Sed < 0.5 MPa by ISO2631-5:2004 and Av < 0.5 m/s(2) by ISO2631-1:1997 on highways and local roads. That means Recreational Vehicle operators driving more than 8 h a day, have a low probability of adverse health effects. Also, for the recreational vehicle, vibration was taken at different speeds (40-60 km/h, 80 km/h, 100-120 km/h). However, the speed change did not appear to affect the vibration dose variation while driving a vehicle on the highway and road. Finally, the health effect index of ISO2631-5:2004 are almost the same as assessment of health effect by ISO2631-1:1997.