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Utilization of vehicle connectivity for improved energy consumption of a speed harmonized cohort of vehicles.

Michigan Technological University-Christopher Morgan, Darrell Robinette, Pruthwiraj Santhosh, John Bloom-Edmonds
  • Technical Paper
  • 2020-01-0587
To be published on 2020-04-14 by SAE International in United States
Improving vehicle response through advanced knowledge of traffic behavior can lead to large improvements in energy consumption for the single isolated vehicle. This energy savings across multiple vehicles can even be larger if they travel together as a cohort in harmonization. Additionally, if the vehicles have enough information about their immediate path of travel, and other vehicles’ in that path (and their respective critical forward looking information), they can safely drive close enough to each other to share aerodynamic load. These energy savings can be upwards of multiple percentage points, and are dependent on several criteria. This analysis looks at criteria that contributes to energy savings for a cohort of vehicles in synchronous motion, as well as describes a study that allows for better understanding of the potential benefits of different types of cohorted vehicles in different platoon arrangements. The basis of this study is a precursor to developing a connected vehicle application that safely allows for fully controlled platooning on open highway for multi-destination vehicles. In this study, two types of light duty passenger…
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Platooning Vehicles Control for Balancing Coupling Maintenance and Trajectory Tracking

Kubota Corp.-Ayumi Suzuki
The University of Tokyo-Rui Fukui, Qiwei Ye, Shin’ichi Warisawa
  • Technical Paper
  • 2020-01-0128
To be published on 2020-04-14 by SAE International in United States
Recently, car-sharing services using ultra-compact mobilities have been attracting attention as a means of transportation for one or two passengers in urban areas. A platooning system consisting of a manned leader vehicle and unmanned follower vehicles can reduce vehicle distributors. We have proposed a platooning system which controls vehicle motion based on the relative position and posture measured by non-contact coupling devices installed between vehicles. The feasibility of the coupling devices was validated through a HILS experiment. There are two basic requirements for realizing our platooning system; (1) all devices must remain coupled and (2) follower vehicles must be able to track the leader vehicle trajectory. Thus, this paper proposes two vehicle control method for satisfying those requirements. They are the “device coupling and trajectory tracking merging method” and the “trajectory shifting method”. The device coupling and trajectory tracking merging method consisting of a coupling keeping controller and a trajectory tracking controller. The predominant controller is chosen according to the amount of the coupling device error and the trajectory tracking error. The trajectory shifting method…
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Identifying Cut-In Vehicles by Fusing Radar and Vision Data for Truck Platooning Safety

Texas A & M University, College Station-Mengke Liu, Sivakumar Rathinam, Mike Lukuc, Swaminathan Gopalswamy
  • Technical Paper
  • 2020-01-0102
To be published on 2020-04-14 by SAE International in United States
Truck platooning systems (Level 2) extend the radar, camera and vehicle-to-vehicle communications based, cooperative adaptive cruise control to provide precise automated lateral and longitudinal vehicle control in order to maintain a tight formation of vehicles with short following distances. A manually driven truck leads a platoon, while the steering, acceleration and braking of following truck(s) are automatically controlled with the driver(s) engaged, monitoring system performance and the driving environment at all times. Level 1 truck platooning has already demonstrated the potential for significant fuel savings, enhanced mobility, and associated emissions reductions from platooning vehicles. Level 2 automation may increase these benefits while reducing driver workload and increasing safety. The objective of this work is to address fundamental problems that arise when vehicles present in the adjacent lanes of the platooning vehicles maneuver to change lanes and cut into the gap between the platooning trucks. The sensing systems in the platooning trucks must be able to identify and estimate the state of these "cut-in" vehicles in real-time so that suitable control actions can be taken. The…
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Impact to Cooling Airflow from Truck Platooning

National Renewable Energy Laboratory-Chen Zhang, Michael P. Lammert
  • Technical Paper
  • 2020-01-1298
To be published on 2020-04-14 by SAE International in United States
We investigate tradeoffs between the airflow strategies related to engine cooling and the aerodynamic-enabled fuel savings created by platooning. By analyzing cooling air flow, operating temperatures and platoon aerodynamics, we recommend configurations (including gaps distances and offsets) that will balance these tradeoffs. Previously, we have collected wind and thermal data for numerous heavy duty truck platoon configurations (gaps ranging from 4 to 87 meters) and reported the significant fuel savings enabled by these configurations. The fuel consumption for all trucks in the platoon were measured using the SAE J1321 gravimetric procedure as well as calibrated J1939 instantaneous fuel rate while travelling at 65 mph and loaded to a gross weight of 65,000 lb. Using COBRA probes and thermocouples mounted 1 m ahead of each truck, anemometers at the grill and a grid of underhood thermocouples as well as J1939 reported engine temperatures, we analyze the impact to critical operating temperatures from different platoon configurations. We created a CFD model to expand understanding of the cooling impacts measured on the test track. Results show significant changes…
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Cooperative Estimation of Road Grade Based on Multidata Fusion for Vehicle Platoon with Optimal Energy Consumption

Jilin University-Fangwu Ma, Yu Yang, Jiawei Wang, Yang Zhao, Yucheng Shen, Guanpu Wu
The Ohio State University-Bilin Aksun Guvenc, Levent Guvenc
  • Technical Paper
  • 2020-01-0586
To be published on 2020-04-14 by SAE International in United States
The platooning of automated vehicles possesses the significant potential of reducing energy consumption in the Intelligent Transportation System (ITS). Moreover, with the rapid development of eco-driving technology, vehicle platoon can further enhance the fuel efficiency by optimizing the efficiency of the powertrain. Since road grade takes great account effectting energy consumption of vehicle, the estimation of the road grade with high accuracy is the key factor for connected vehicle platoon to optimize energy consumption using vehicle-to-vehicle (V2V) communication. Commonly the road grade is quantified by single consumer grade global positioning system (GPS) with the geodetic height data which is rough in meter-level, increasing the difficulty to precisely estimate the road grade. This paper presents a novel cooperative estimation method Extended Kalman Filter (EKF) to obtain the accurate information of slopes by multidata fusion of GPS, Inertial Measurement Unit (IMU) using vehicle platoon communication, i.e. the following vehicle fuses the data which was measured by the on-board sensors and delivered by the proceding vehicle. Considering the accurate road grade information, the fuel consumption optimazition of the…
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Engine-in-the-loop study of a hierarchical predictive online controller for connected and automated heavy-duty vehicles

Clemson University-Mohammad Naghnaeian
North Carolina State University-Ben Groelke, Christian Earnhardt, Christopher Vermillion
  • Technical Paper
  • 2020-01-0592
To be published on 2020-04-14 by SAE International in United States
This paper presents a cohesive set of engine-in-the-loop (EIL) studies examining the use of hierarchical model-predictive control for fuel consumption minimization in a class-8 heavy-duty truck intended to be equipped with Level-1 connectivity/automation. This work is motivated by the potential of connected/automated vehicle technologies to reduce fuel consumption in both urban/suburban and highway scenarios. We begin by presenting a hierarchical model-predictive control scheme that optimizes multiple chassis and powertrain functionalities for fuel consumption. These functionalities include: vehicle routing, arrival/departure at signalized intersections, speed trajectory optimization, platooning, predictive optimal gear shifting, and engine demand torque shaping. The primary optimization goal is to minimize fuel consumption, but the hierarchical controller explicitly accounts for other key objectives/constraints, including operator comfort and safe inter-vehicle spacing. The main focus of this work is on a sequence of EIL studies intended for evaluating the computational costs and fuel savings associated with these algorithms. These EIL studies involve both the open-loop playback of simulation-based evaluation studies as well as the closed-loop validation of the proposed control strategies, both individually and combined. These…
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Impact of Lateral Alignment on the Energy Savings of a Truck Platoon

Auburn University-Patrick Smith, Mark Hoffman, David Bevly
National Renewable Energy Laboratory-Michael P. Lammert
  • Technical Paper
  • 2020-01-0594
To be published on 2020-04-14 by SAE International in United States
A truck platooning system was tested on two heavy-duty tractor-trailer trucks on a closed test track to investigate the sensitivity of manual lateral control and intentional lateral offsets over a range of inter-vehicle spacing. The fuel consumption for both trucks in the platoon was measured using the SAE J1321 gravimetric procedure while travelling at 65 mph and loaded to a gross weight of 65,000 lb and in addition a calibrated SAE J1939 instantaneous fuel rate was calculated to serve as proxies for additional analyses. The testing campaign demonstrated the effects of: inter-vehicle gaps, following vehicle lateral offsets, following vehicle longitudinal and lateral control impacts, NOx emission impacts of platooning and cooling air flow impacts of platooning. The new results are compared to past truck platooning studies to reinforce the value of the new information. The results showed that energy savings generally increased in a non-linear fashion as the gap was reduced. The impacts of different following-truck lateral offsets had a measurable impact and the value of lateral control evaluated. The fuel-consumption savings on the curves…
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Impact of Mixed Traffic on the Energy Savings of a Truck Platoon

Auburn University-Patrick Smith, Mark Hoffman, David Bevly
National Renewable Energy Laboratory-Michael Lammert
  • Technical Paper
  • 2020-01-0679
To be published on 2020-04-14 by SAE International in United States
A two-truck platooning system was tested on a closed test track in a variety of realistic traffic and transient operating scenarios - conditions that truck platoons are likely to face on real highways. The fuel consumption for both trucks in the platoon was measured using the SAE J1321 gravimetric procedure as well as calibrated J1939 instantaneous fuel rate, serving as proxies to evaluate the impact of aerodynamic drag-reduction under constant-speed conditions. These measurements demonstrate the effects of: cut-in and cut-out maneuvers by other vehicles, transient traffic, the use of mismatched platooned vehicles (van trailer mixed with flatbed trailer), platoon following another truck with adaptive cruise control (ACC) and the presence of a multiple-passenger-vehicle pattern ahead of and adjacent to the platoon. These scenarios are intended to address the possibility of “background aerodynamic platooning” impacting realized savings on public roads. Using calibrated J1939 fuel rate analysis, fuel savings for curved track sections vs straight track sections was also evaluated for these scenarios. The presence of passenger-vehicle traffic patterns had a measurable impact on platoon performance, but…
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LiDAR-Based Urban Autonomous Platooning Simulation

FEV North America Inc.-Hamzeh Alzu'bi, Tom Tasky
  • Technical Paper
  • 2020-01-0717
To be published on 2020-04-14 by SAE International in United States
The technological advancements of Advanced Driver Assistance Systems (ADAS) sensors enable the ability to achieve autonomous vehicle platooning, increase the capacity of road lanes, and reduce traffic. This article focuses on developing urban autonomous platooning using LiDAR and GPS sensors in a simulation environment. Gazebo simulation is utilized to simulate the sensors, vehicles, and testing environment. Two vehicles are used in this study; a lead vehicle that follows a preplanned trajectory, while the remaining vehicle (follower) uses the LiDAR object detection and tracking information to follow the lead vehicle. The LiDAR object detection is handled in stages: point clouds frame transformation, filtering and down-sampling, ground segmentation, and clustering. The tracking algorithm uses the clustering information to provide position and velocity of the lead vehicle which allows for vehicles platooning. This paper covers the LIDAR object detection and tracking algorithms as well as the autonomous platooning control algorithms. The developed control algorithms were tested in a simulation environment. Test results illustrate that the follower vehicle was able to attain the autonomous platooning based on the LiDAR…
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Model Predictive Platoon Control of Connected Hybrid Electric Vehicles

School of Aerospace Engineering, Xiamen University, China Sh-Wang Ban, Li Wenchang
Xiamen University, China-Guo Jinghua
  • Technical Paper
  • 2020-01-5031
Published 2020-02-24 by SAE International in United States
This paper presents a model predictive platoon control method for connected hybrid electric vehicles (CHEVs) to improve the safety, fuel economy, and riding comfort of CHEVs. First, the model of platooning CHEVs is established to describe the nonlinear and discrete characteristics of CHEVs, which consists of engine model, motor model, battery pack model, vehicle longitudinal dynamic model and so on. Then, a model predictive controller(MPC) for platooning CHEVs is proposed, a robust prediction model is build based on feedback correction to compensate the prediction state error caused by model mismatch and improve the accuracy and robustness, and the control increment in each sampling period is set as the control variable in the cost function to avoid the sudden change of the control variable that will be prone to poor control results and unfeasible solutions. Next, the dynamic coordination control rules between the power sources of CHEVs are presented. Finally, the results show that the proposed MPC platoon controller can improve both fuel economy and riding comfort of CHEVs meanwhile explicitly satisfying the tracking capability.
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