Automotive Science and Engineering

---

In this paper, an adaptive rule based controller for an anti-lock regenerative braking system (ARBS) of a series hybrid electric bus (SHEB) has been proposed. The proposed controller integrates the regenerative braking and wheel anti-lock functions by controlling the electric motor of the hybrid vehicle, without using any conventional mechanical anti-lock braking system. The performance of the proposed system is evaluated by a comprehensive vehicle dynamics model in MATLAB/Simulink. Using the designed ARBS, the braking and regenerative performances of SHEB have significantly improved in slippery roads while the slip ratios are kept between 0.15 and 0.20.

---

---

During the design and development of truck cabins, the safety of the driver and the front seat passenger in an accident is an important task and should be considered. The cab must be designed in such a way that in an accident a sufficient survival space is guaranteed. The aim of this study is to investigate the behavior of Iran Khodro (IKCO) 2624 truck subjected to a complex crash test according to regulation ECE-R29. This regulation is a comprehensive European regulation consisting of three tests: 1-Front impact test (Test A), 2- Roof strength test (Test B), 3-Rear wall strength test (Test C). These tests do not consider the safety of the occupant directly however, a III-50th% dummy was used to assess the cab’s deformations relative to the driver survival space. A 3D finite element model of the cab and chassis was developed and subjected to tests by using LS-DYNA software. The results indicate that the cab complied with Test A and C successfully while it passed Test B marginally. Finally, two solutions are suggested and implemented to improve the cab’s response for Test B.

---

In the present study, a model of a large Lithium Polymer (Li-Po) battery for use in the simulation of Hybrid Electric Vehicles (HEVs) is developed. To attain this goal, an Equivalent Circuit (EC) consisting of a series resistor and two RC parallel networks is considered. The accuracy and the response time of the model for use in an HEV simulator are studied. The battery parameters identification and model validation tests are performed in low current with a good accuracy. Similar test process is implemented in high current for another cell and the simulation is verified with experimental results. The validation tests confirm the accuracy of the model for use in HEV simulator. Finally, the battery model is used to model a Vehicle, Fuel and Environment Research Institute (VFERI) hybrid electric city bus using ADVISOR software and its compatibility with other components of the vehicle simulator are demonstrated in a drive cycle test.

---

In this paper, the development and optimization of Power Distribution Control Strategy (PDCS) have been performed for a Hybrid Energy Storage Systems (HESS) of a Series Hybrid Electric Bus (SHEB). A common PDCS is based on the use of Ultra-Capacitor (UC) pack. A new simple PDCS is developed as a battery based one. For the battery based PDCS, four parameters are introduced for tuning the PDCS performance. The Design of Experiment (DoE) method is utilized to optimize the parameters of the battery based PDCS for the driving cycles and the vehicle controllers. The results show the optimized battery based PDCS performance for some cases are better than the UC based PDCS performance. Vice versa, for some cases the performance of the UC based PDCS is better than the battery based PDCS. Finally, the costs rising from the HESS (about 66%) is reasonable when considering the over double increase in the battery life-time when using an appropriate PDCS.

---

In the present paper, the idea of braking energy regeneration and reusing that energy during acceleration for a refuse truck is comprehended. According to their driving cycle, the refuse trucks have a good potential for braking energy regeneration. On the other hand, hydraulic hybrid is a powertrain with high power density which is appropriate for energy regeneration. In the primary stage of this issue, the hydraulic hybrid propulsion system is designed with intention of regenerating the maximum possible kinetic energy during the refuse truck braking mode. At this stage, a non-fuzzy rule-based control strategy is applied to manage the energy flow in the hybrid powertrain. After that, the powertrain of the Axor 1828 truck and the elements of the hydraulic powertrain are modeled in MATLAB/Simulink. The modeling is performed considering the efficiencies of the powertrain elements. In the last part of the paper, a fuzzy control strategy is designed and modeled to improve the fuel consumption of the truck with hybrid powertrain. In order to see the usefulness of the designed hybrid powertrain, several simulations are organized on the vehicle model in Simulink. The driving cycle for refuse truck in Tehran is used for performing the simulations. The results state indicated that using the hydraulic hybrid powertrain decreased the fuel consumption of the refuse truck by 7 percent. In addition, this amount of reduction was improved by implementing the fuzzy control strategy. The decrease in fuel consumption was due to the regenerating of the braking energy up to 50 percent.

---

The Energy Storage System (ESS) is an expensive component of an E-bike. The idea of Hybrid Energy Storage System (HESS), a combination between battery and Ultra-Capacitor (UC), can moderate the cost of E-bike ESS. In this paper, a cost function is developed to use for optimal sizing of a HESS. This cost function is consisted of the HESS (battery, UC and DC/DC converter) cost and the cost of battery replacements during 10 years. The battery lifetime and riding pattern limit the life span of ESS. The “Portuguese standard NP EN 1986-1” riding pattern is used in this research. The Genetic Algorithm (GA) is used to solve the optimization problem. The results show that the cost and weight of HESS are clearly better than optimally sized battery ESS.

---

This article investigates the effects of using a thin-walled structure in the chassis front rails in the automotive industry. In frontal accidents, the front rails of the vehicle chassis, increases vehicle crash-worthiness and occupants’ safety by plastic deformation, energy absorption, increasing the crash duration and reducing the load and injuries to the occupants. The objective is to optimize the thin-walled structure of the bumper and the direct beams in the front chassis rails. An explicit FEM full vehicle model with a dummy, safety belts, and air bags are used for the modeling and analysis of the applied loads on the vehicle and the occupants. The FMVSS No. 208 and ECE No. 94 standards are considered for the simulation of a vehicle accident. Finally, the proper model will be selected based on the results.
 

---

Hybrid electric vehicles employ a hydraulic braking system and a regenerative braking system together to provide enhanced braking performance and energy regeneration. In this paper an integrated braking system is proposed for an electric hybrid vehicle that include a hydraulic braking system and a regenerative braking system which is functionally connected to an electric traction motor. In the proposed system, four independent anti-lock fuzzy controllers are developed to adjust the hydraulic braking torque in front and rear wheels. Also, an antiskid controller is applied to adjust the regenerative braking torque dynamically.  A supervisory controller, is responsible for the management of this system.  The proposed integrated braking system is simulated in different driving cycles. Fuzzy rules and membership functions are optimized considering the objective functions as SoC and slip coefficient in various road conditions. The simulation results show that the fuel consumption and the energy loss in the braking is reduced. In the other hand, this energy is regenerated and stored in the batteries, especially in the urban cycles with high start/stop frequency. The slip ratio remains close to the desired value and the slip will not occur in the whole driving cycle. Therefore, the proposed integrated braking system can be considered as a safe, anti-lock and regenerative braking system.
 

---

Driving cycle is used to assess fuel consumption, pollutant emissions and performance of the vehicle. The aim of this paper is to extract the driving cycle for refuse collection truck and estimate its braking energy. For this purpose, after selecting the target truck and geographic area, the equipment needed to measure the required variables were prepared and mounted on the truck. Then, the actual data were collected from the performance of the target Truck while performing its mission. Since the amount of braking energy depends on the speed, truck mass and road grade, the speed of the vehicle is measured simultaneously with the truck mass and road grade. The collected data are then processed and subdivided into micro-trips. The micro-trips are clustered according to the number of state spaces using the K-Means algorithm. Next, the representative micro trips are selected from within the clusters and the final driving cycle is generated. The representative driving cycle shows that the truck speed is zero at 47% of the working time. Finally, the amount of braking power and accumulative braking energy in the driving cycle is calculated.

---

Reducing the fuel consumption and energy use in transportation systems are the active research areas in recent years. This paper considers the repetitive mission of the intercity passenger buses as a case for fuel reduction. A look-ahead energy management system is proposed which uses the information about the geometry and speed limits of the road ahead. This data can be extracted using road slope and speed limits database in combination with a GPS unit. A fuzzy gain scheduling algorithm is proposed to improve the performance of the look-ahead control. The road slope and speed limit specifications called road pattern can define some two dimensional regions. The main parameters of the proposed fuzzy look-ahead controller are optimized in each region using the genetic algorithm.  The final output of the proposed controller is the desired speed that regularly is fed to the conventional cruise controller with new set points. The simulation results of the proposed energy management system show that the fuel consumption is significantly reduced.

---

Global restrictions on the use of fossil fuels in the transportation sector and the commitment to rapid response to the climate change have created a strong incentive to develop fuel-efficient and low-emission vehicle systems. Hydraulic hybrid power train technology is one of the temporary solutions introduced to optimize internal combustion engine (ICE) operation and regenerate braking energy. The hydraulic hybrid power train system (HHPS) has a higher power density than the electric one. So, it is used in heavy vehicles, agricultural and construction machinery that need a high-power density to accelerate or recover the braking energy.  In some trucks, such as refuses collection trucks, fire trucks and delivery trucks, a high percentage of the ICE energy is consumed by the auxiliary systems. In this type of trucks, the hydraulic hybrid power train systems are not very efficient. This paper introduces a hydraulic hybrid auxiliary system (HHAS) concept to manage the energy consumed by the auxiliary system in refuse collection trucks. In the first part of the paper, the configurations and operating modes of series, parallel and hydro-mechanical HHPS are discussed and compared with the HHAS concept. In the following, the conventional refuse collection truck model and refuse truck equipped with HHAS model was developed in MATLAB/SINMULINK and simulated in Tehran refuse collection truck driving cycle. The simulation results show that by using the ​​HHAS concept, the fuel consumption is reduced by 15 percent.

---

This study examines the impact of a fuzzy logic-based control strategy on managing peak power consumption in the auxiliary power unit (APU) of a hybrid electric bus. The APU comprises three components: an air compressor, a power steering system, and an air conditioning system (AC) connected to an electric motor. Initially, these components were simulated in MATLAB-SIMULINK software. While the first two were deemed dependent and independent of vehicle speed, respectively, the stochastic behavior of the steering was emulated using the Monte Carlo method. Subsequently, a fuzzy controller was designed and incorporated into the APU to prevent simultaneous operation of the three accessories as much as possible. The results of repeated simulations demonstrated that the designed fuzzy controller effectively distributed the operation of the accessories throughout the driving cycle, thereby reducing overlaps in auxiliary loads. Consequently, the APU's average and maximum power consumption exhibited significant reductions. Furthermore, through multiple simulations with an upgraded power system model integrating the new APU-controller package, it was established that the proposed strategy for managing auxiliary loads in the bus led to lower fuel consumption and emissions.

---

Due to the importance of vehicle weight reduction which can reduce fuel consumption and air pollution, changes are made in vehicles. In heavy trucks with payload limitations, a lighter trailer can provide higher load-carrying capacity and more economical benefits. Composite materials are a good candidate for material exchange due to their resistance to various conditions and low weight compared to steel. In this paper, the trailer material made of steel will be replaced by composite so that strength density will remain the same. For this purpose, the finite element method is used for static and dynamic analyses. At first, the model of a two-axle trailer is developed using SolidWorks software. Then, using standard loading and failure theories (Tsai-Hill, Tsai-Wu), the number of composite layers and their suitable angles are selected for the chassis. Finally, the loaded trailer's static, modal, and dynamic analysis are performed using the finite element method with a composite material. Results show that 17 layers of polymer composite with glass fibers with 0-0 angle can reduce 17.7 percent weight.

---

The objective of developing kinetic energy recovery systems for vehicles is to repurpose energy otherwise dissipated during braking. Brake energy recovery and storage are achieved through two broad methods: electrical and mechanical, contingent on the energy storage type and the traction system's operational approach. Utilizing a rotating flywheel emerges as a practical, cost-effective, safe, and environmentally friendly means of storing energy, offering an extended service life. This study, synthesizing insights from various theories, aims to devise a prototype brake energy recovery system compatible with Samand car, employing the flywheel tank. Additionally, considerations for the power transmission system and clutch involve designing their type and dimensions, taking many factors into account for the selection. The initial design undergoes simulation and evaluation using MATLAB_SIMULINK and the ADVISOR plugin. The investigation delves into the influence of various design parameters on the efficiency of the system. Subsequently, attempts are undertaken to clarify the factors contributing to varied outcomes. The simulation results indicate a notable decrease in fuel consumption and emissions for a Samand car during urban driving cycles characterized by frequent braking. This improvement is realized through the utilization of a steel flywheel with an incomplete cone geometry and a specified radius. Suggestions are put forth for refining the controller to potentially enhance reductions in fuel consumption and pollution.