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SAE International Journal of Commercial Vehicles
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Development of a Standard Testing Method for Vehicle Cabin Air Quality Index

SAE International Journal of Commercial Vehicles

Emissions Analytics, UK-Nick Molden, Sam Boyle
University of California, Riverside, USA-Liem Pham, Kent Johnson, Heejung Jung
  • Journal Article
  • 02-12-02-0012
Published 2019-05-20 by SAE International in United States
Vehicle cabin air quality depends on various parameters such as number of passengers, fan speed, and vehicle speed. In addition to controlling the temperature inside the vehicle, HVAC control system has evolved to improve cabin air quality as well. However, there is no standard test method to ensure reliable and repeatable comparison among different cars. The current study defined Cabin Air Quality Index (CAQI) and proposed a test method to determine CAQI. CAQIparticles showed dependence on the choice of metrics among particle number (PN), particle surface area (PS), and particle mass (PM). CAQIparticles is less than 1 while CAQICO2 is larger than 1. The proposed test method is promising but needs further improvement for smaller coefficient of variations (COVs).
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Improving Multi-Axle Vehicle Steering Coordination Performance Based on the Concept of Instantaneous Wheel Turn Center

SAE International Journal of Commercial Vehicles

GAC Automotive Research & Development Center, China-Bo Wang, Hongshan Zha, Guoqi Zhong, Shijing Weng, Qin Li
Jilin University, China-Pingping Lu
  • Journal Article
  • 02-12-02-0010
Published 2019-03-14 by SAE International in United States
A new concept of instantaneous wheel turn center (IWTC) is proposed to evaluate and improve multi-axle vehicle steering coordination performance. The concept of IWTC and its calculation method are studied. The index named dispersion of IWTC is developed to evaluate the vehicle steering coordination performance quantitatively. The simulation tests based on a three-axle off-road vehicle model are conducted under different vehicle velocities and lateral accelerations. The simulation results show that the turn centers of different wheels are disperse, and the dispersion becomes larger with the increase of vehicle velocities and lateral acceleration. Since suspension has important influences on vehicle steering performance, the genetic algorithm is used to optimize the suspension hard points and bushing stiffness, aiming at minimizing the dispersion of wheel turn centers (DWTC) to improve the vehicle steering coordination performance. The optimization results indicate that the suspension optimization can effectively reduce the DWTC and improve the vehicle steering coordination performance. The proposed wheel turn center method provides an index and tool for the suspension design and optimization in the pre-development phase of the…
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Prediction and Control of Response Time of the Semitrailer Air Braking System

SAE International Journal of Commercial Vehicles

Jiangsu University, China-Ren He, Chang Xu
  • Journal Article
  • 02-12-02-0011
Published 2019-05-09 by SAE International in United States
The response time of the air braking system is the main parameter affecting the longitudinal braking distance of vehicles. In this article, in order to predict and control the response time of the braking system of semitrailers, an AMESim model of the semitrailer braking system involving the relay emergency valve (REV) and chambers was established on the basis of analyzing systematically the working characteristics of the braking system in different braking stages: feedback braking, relay braking, and emergency braking. A semitrailer braking test bench including the brake test circuit and data acquisition system was built to verify the model with typical maneuver. For further evaluating the semitrailer braking response time, an experiment under different control pressures was carried out. Experimental results revealed the necessity of controlling the response time. As a result, a braking pressure compensation system was designed through adding intake and exhaust solenoid valves to the original braking system. A proportional-integral-derivative (PID) control strategy optimized by genetic algorithm (GA) was adopted to generate pulse width modulation (PWM) signals applied to the solenoid valves…
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Development of a Learning Capability in Virtual Operator Models

SAE International Journal of Commercial Vehicles

Iowa State University, USA-Yu Du, Michael C. Dorneich, Brian L. Steward
  • Journal Article
  • 02-12-02-0009
Published 2019-03-14 by SAE International in United States
This research developed methods for a virtual operator model (VOM) to learn the optimal control inputs for operation of a virtual excavator. Virtual design, used to model, simulate, and test new features, has often been limited by the fidelity of the virtual model of human operators. Human operator learns, over time, the capability, limits, and control characteristics of new vehicles to develop the best strategy to maximize the efficiency of operation. However, VOMs are developed with fixed strategies and for specific vehicle models (VMs) and require time-consuming re-tuning of the VOM for each new vehicle design. Thus, there typically is no capability to optimize strategies, taking account of variation in vehicle capabilities and limitations. A VOM learning capability was developed to optimize control inputs for the swing-to-pile task of a trenching operation. Different control strategies consisted of varied combinations of speed control, position control, and coast. A genetic algorithm (GA) was used to search for the best strategies and transition parameters to operate two vehicle design iterations. In the first design iteration, a combination of…
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Electrifying Long-Haul Freight—Part II: Assessment of the Battery Capacity

SAE International Journal of Commercial Vehicles

University of Kansas, USA-Christopher Depcik, Anmesh Gaire, Jamee Gray, Zachary Hall, Anjana Maharjan, Darren Pinto, Arno Prinsloo
  • Journal Article
  • 02-12-02-0007
Published 2019-01-25 by SAE International in United States
Recently, electric heavy-duty tractor-trailers (EHDTTs) have assumed significance as they present an immediate solution to decarbonize the transportation sector. Hence, to illustrate the economic viability of electrifying the freight industry, a detailed numerical model to estimate the battery capacity for an EHDTT is proposed for a route between Washington, DC, to Knoxville, TN. This model incorporates the effects of the terrain, climate, vehicular forces, auxiliary loads, and payload in order to select the appropriate motor and optimize the battery capacity. Additionally, current and near-future battery chemistries are simulated in the model. Along with equations describing vehicular forces based on Newton’s second law of motion, the model utilizes the Hausmann and Depcik correlation to estimate the losses caused by the capacity offset of the batteries. Here, a Newton-Raphson iterative scheme determines the minimum battery capacity for the required state of charge. Consequently, the model demonstrates different combinations of battery capacities and payloads while checking minimum conditions of brake torque, motor torque, and current draw. Most importantly, battery life and aging effects are included to account for…
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Separable and Standard Monte Carlo Simulation of Linear Dynamic Systems Using Combined Approximations

SAE International Journal of Commercial Vehicles

Grand Valley State University, USA-Mahdi Norouzi
University of Toledo, USA-Efstratios Nikolaidis
  • Journal Article
  • 02-12-02-0008
Published 2019-01-25 by SAE International in United States
Reliability analysis of a large-scale system under random dynamic loads can be a very time-consuming task since it requires repeated studies of the system. In many engineering problems, for example, wave loads on an offshore platform, the excitation loads are defined using a power spectral density (PSD) function. For a given PSD function, one needs to generate many time histories to make sure the excitation load is modeled accurately. Global and local approximation methods are available to predict the system response efficiently. Each way has their advantages and shortcomings. The combined approximations (CA) method is an efficient method, which combines the advantages of local and global approximations. This work demonstrates two methodologies that utilize CA to reduce the cost of crude or separable Monte Carlo simulation (MCS) of linear dynamic systems when the excitation loads are defined using PSD functions. The system response is only calculated at a few frequencies within the range of the PSD function, and CA is used to estimate the response for the other frequencies of excitation. This approach significantly reduces…
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