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Technical Paper

The Role of Safety Critical Architecture in an Evolving Ecosystem

2021-04-15
2021-01-1000
There are many industries where safety is a major, if not the primary, concern, such as aviation and nuclear power. These industries rely on many layers of standards for designing, developing, and deploying safety critical systems and technologies. While UAS operations and UAS Traffic Management (UTM) are often touted as “safety critical”, the systems and technologies are not being held to the same standards as traditional aviation, with its long pedigree of safety. There are multiple reasons for this dichotomy. One such reason is that design assurance standards, such as DO-178 for software, do not fit with modern technology such as web-based communication and machine learning. At the architecture level, the federated approach to UTM has led to a void in the Systems Engineering process. Nobody “owns” the entire system and therefore nobody owns the Systems Engineering process where many safety related design decisions are traditionally made.
Technical Paper

Roadside Lidar Helping to Build Smart and Safe Transportation Infrastructure

2021-04-15
2021-01-1013
As part of its research in transportation infrastructure, the University of Nevada, Reno’s Nevada Center for Applied Research, in conjunction with the Regional Transportation Commission of Washoe County and the Nevada DOT, used Velodyne’s lidar sensors to collect data aimed at making transportation more efficient, sustainable and safe. This paper summarizes the research results and data obtained by UNR’s Nevada Center for Applied Research. The program integrated Velodyne Ultra Puck lidar sensors with traffic signals to detect, count and track pedestrians, cyclists and traffic. It leveraged the data captured with the sensors to help improve traffic analytics, congestion management and pedestrian safety. The initial lidar sensor was placed at a Reno intersection in 2017. A review of studies and data indicates this may have been the first-ever application of lidar on a traffic signal.
Technical Paper

Safe Operations at Roadway Junctions – Design Principles from Automated Guideway Transit

2021-04-15
2021-01-1004
A system-level view of a fully automated transit system comprising a fleet of automated vehicles (AVs) in driverless operation, each with an SAE Level 4 Automated Driving System (ADS), related safety infrastructure and other system equipment is compared to the automatic train control system used in automated guideway transit (AGT) technology. Drawing from the safety principles, analysis methods and risk assessments of AGT systems, comparable functional subsystem definitions are proposed for AV fleets in driverless operation. With the prospect of multiple AV fleets operating within a single automated mobility district (AMD), the criticality of protecting roadway junctions requires an approach like that of automated fixed-guideway transit systems in which a guideway switch zone “interlocking” is installed at each junction location.
Technical Paper

Correlation between Sensor Performance, Autonomy Performance and Fuel-Efficiency in Semi-Truck Platoons

2021-04-06
2021-01-0064
Semi-trucks, specifically class-8 trucks, have recently become a platform of interest for autonomy systems. Platooning involves multiple trucks following each other in close proximity, with only the lead truck being manually driven and the rest being controlled autonomously. This approach to semi-truck autonomy is easily integrated on existing platforms, reduces delivery times, and reduces greenhouse gas emissions via fuel economy benefits. Level 1 SAE fuel studies were performed on class-8 trucks operating with the Auburn Cooperative Adaptive Cruise Control (CACC) system, and fuel savings up to 10-12% were seen. Enabling platooning autonomy required the use of radar, global positioning systems (GPS), and wireless vehicle-to-vehicle (V2V) communication. Poor measurements and state estimates can lead to incorrect or missing positioning data, which can lead to unnecessary dynamics and finally wasted fuel.
Technical Paper

Experimental Fuel Consumption Results from a Heterogeneous Four-Truck Platoon

2021-04-06
2021-01-0071
Platooning has the potential to reduce greenhouse gas emissions of heavy-duty vehicles. Prior platooning studies have chiefly focused on the fuel economy characteristics of two- and three-truck platoons, and most have investigated aerodynamically homogeneous platoons with trucks of the same trim. For real world application and accurate return on investment for potential adopters, non-uniform platoons and the impacts of grade and disturbances on a platoon’s fuel economy must also be characterized. This study investigates the fuel economy of a heterogeneous four-truck platoon on a closed test track. Tests were run for one hour at a speed of 45 mph. The trucks used for this study are two 2015 Peterbilt 579’s with a Cummins ISX15 and a Paccar MX-13, and two 2009 Freightliner M915A5’s, one armored and the other unarmored. Many analysis methodologies were leveraged to describe and compare the fuel data, including lap-wise and track-segment analysis.
Technical Paper

Virtual Evaluation of Seat Shake Performance Using Four Poster Shaker

2021-04-06
2021-01-0325
For the designing of world class vehicles, ride comfort is one of the criteria that vehicle manufacturers are constantly trying to improve. The automotive seating system is an important sub-system in a vehicle that contributes to the ride comfort of the vehicle occupants. Seat vibrations are perceived by the occupants and make them feel uncomfortable during driving conditions. These vibrations are majorly transferred from engine and road excitation loads. For road excitation loads, the road testing may not be accurately repeatable, and measurements based on four post shakers are used to assess the discomfort. The major challenges for the vehicle manufactures is the availability of physical prototypes at an early stage of vehicle development and any changes in the design due to test validation leads to huge cost and time.
Technical Paper

Structural Design and Simulation Analysis of an Intelligent Speed Bump

2021-04-06
2021-01-0324
As a traffic deceleration device, speed bumps are widely used to reduce the speed of vehicles and have a good effect. However, in special occasions such as hospital entrance, the bumps caused by ordinary speed bumps are likely to aggravate the pain of patients. In view of this situation, an intelligent speed bump is designed in this paper, which can adjust the height of the speed bump according to the speed of the passing vehicles. When a low-speed vehicle passes by, the elastic link slider module works, so that the upper surface of the speed bump can be elastically lowered to improve the ride comfort of low-speed vehicles. When a high-speed vehicle passes by, the centrifugal locking module will lock the elastic link slider module, and the upper surface of the speed bump will be locked, which plays a role in speed limit. In this paper, SolidWorks and ADAMS/car are used to analyze the process of vehicle passing through the intelligent speed bump.
Technical Paper

Research and Parameter Optimization on Ride Comfort and Road Friendliness of Interconnected Air Suspension for Commercial Vehicles

2021-04-06
2021-01-0316
In order to improve the ride comfort and road friendliness of heavy commercial vehicles, a lateral interconnected air suspension system is developed. Based on the theory of thermodynamics and vehicle dynamics, a Ten-degree-of-freedom vehicle dynamics model with lateral interconnected air suspension is established. Interconnected pipeline parameters’ influence on characteristics of air suspension system in whole vehicle are calculated and analyzed. Simulation results show that the stiffness of air suspension decreases gradually with the increase of interconnected pipeline diameter. The designed interconnected air spring experiments verify the simulation results. Simulation on vehicle dynamics models is carried out by building random road models with different roughness levels in MATLAB.
Technical Paper

An Investigation of Aerodynamic Characteristics of Three Bluff Bodies in Close Longitudinal Proximity - Part 2

2021-04-06
2021-01-0952
The work described in this paper is a continuation of an investigation into the effects of systematic changes in upper-body geometry on the aerodynamic drag of passenger-car-like bluff-body models in close longitudinal proximity and operating in platoon formations. The original work, presented in SAE paper 2019-01-0659, showed measurements of the aerodynamic drag of individual models within three-model platoons and for which each model was tested in three different upper-body configurations This provided a data-set of 27 platoon configurations to compare with the three baseline conditions of the isolated models. The work contrasted with other published platooning research in which the spacing, between homogeneous models in the platoons, was the only variable to be considered. In this publication the results of further wind tunnel tests, using the same models as before but in two-model platoons, providing a further 9 test configurations are compared with the original data.
Technical Paper

Analysis of the Unsteady Wakes of Heavy Trucks in Platoon Formation and Their Potential Influence on Energy Savings

2021-04-06
2021-01-0953
The authors present transient wind velocity measurements from two successive, well-documented truck platooning track-test campaigns to assess the wake-shedding behavior experienced by trucks in various platoon formations. Utilizing advanced analytics of data from fast-response (100-200-Hz) multi-hole pressure probes, this analysis examines aerodynamic flow features and their relationship to energy savings during close-following platoon formations. Applying Spectral analysis to the wind velocity signals, we identify the frequency content and vortex-shedding behavior from a forward truck trailer, which dominates the flow field encountered by the downstream trucks. The changes in dominant wake-shedding frequencies correlate with changes to the lead and follower truck fuel savings at short separation distances.
Technical Paper

Stereo Vision Based Pothole Detection System for Improved Ride Quality

2021-04-06
2021-01-0085
Stereo vision based sensing systems have gained significant attention during the last two decades due to its reliable and accurate obstacle detection and recognition capabilities. Such systems with advanced processing units are now widely used in partially automated vehicles to improve passengers’ safety and comfort level. A predictive suspension control system that could provide better ride comfort and safety to the passengers by detecting potholes in advance and control the suspension system accordingly has been investigated in this study. Potholes can become serious safety hazard and can often cause discomfort if not detected and maneuvered at the right time. In this paper, a novel stereo vision based pothole detection system is proposed that detects pothole and calculates its depth accurately.
Technical Paper

Arrangement and Control Method of Cooperative Vehicle Platoon

2021-04-06
2021-01-0113
With the development of cellular communication technology and for the sake of reducing drag resistance, the multi-lane platoon technology will be more prosperous in the future. In this article, the cooperative vehicle platoon method on the public road is represented. The method’s architecture is mainly composed of the following parts: decision-making, path planning and control command generation. The decision-making uses the finite state machine to make decision and judgment on the cooperative lane change of vehicles, and starts to execute the lane change step when the lane change requirements are met. In terms of path planning, with the goal of ensuring comfort, the continuity of the vehicle state and no collision between vehicles, a fifth-order polynomial is used to fit every vehicle trajectory. In terms of control command generation module, a model predictive control algorithm is used to solve the multi-vehicle centralized optimization control problem.
Technical Paper

Investigation of the Interaction between the Vehicle Vertical Vibration and Driveline Torsional Vibration Using A Hydro-Pneumatic Limited Bandwidth Active Suspension System

2021-04-06
2021-01-0700
1 Rear wheel drive vehicles have a long driveline using a propeller shaft with two universal joints. Consequently, in this design usage of universal joints within vehicle driveline is inevitable. However, the angularity of the driveshaft resulting from vertical oscillations of the rear axle causes many torsional and bending fluctuations of the driveline. Unfortunately, most of the previously published research work in this area assume the propeller inclination angle is constant under all operating conditions. As a matter of fact, this assumption is not accurate due to the vehicle body attitudes either in pitch or bounce motions. Where the vehicle vibration due to the suspension flexibility, either passive or active type, exists.
Technical Paper

Practical Approach to Enhance Gear Shift Quality in Automatic Transmissions

2021-04-06
2021-01-0688
Passenger utility vehicles like car, SUVs, MPVs are used in wide application all over the world. Luxuries are becoming essential features of product mix along with comfort and ergonomics. Customer desires best shift quality with emerging technologies like AT, DCT, CVT, etc. and every OEM is working hard to achieve it. It is very difficult to satisfy the customer desire because of diversities in demographics and geographic. Gear shift quality (GSQ) is very crucial touch point in overall drive feel of vehicle. It consist of various parameters like mode selection feel, precision, comfort, select Noise, etc. It demands tradeoff practices among various parameters as stated. In this paper, external mode selection system of automatic transmission is explained. Various contributing parameters are explained with practical design approach for detent profile, mode selection mechanism, cable & dampers, etc.
Technical Paper

Infrastructure Camera Video Data Processing of Traffic at Roundabouts

2021-04-06
2021-01-0165
Roundabout is a unique approach of managing traffic at intersections because it relies on driver’s instincts of safety. Roundabouts are considered safer than other ways of intersection traffic management due to low speed limits, smoother merging, and reduced fatal accidents. Despite their benefits and increasing usage, there is lack of clear understanding of the roundabouts, particularly due to scarcity of data and simulation models and the complexity of the structure. Real-time and offline traffic data recorded at a roundabout provides a basis for 1) identification of the safety issues, 2) understanding unexpected and risky driver behavior, 3) proposing potential mobility solutions, and 4) developing simulation models. The processed data may be used in controlling metered roundabouts, communicating with connected and automated vehicles (CAVs) etc. In this paper an approach to obtain useful traffic information from video feed data at a roundabout is presented.
Technical Paper

Infrastructure-Based Sensor Data Capture Systems for Measurement of Operational Safety Assessment (OSA) Metrics

2021-04-06
2021-01-0175
The operational safety of automated driving system (ADS)-equipped vehicles (AVs) needs to be quantified for an understanding of risk, requiring the measurement of parameters as they relate to AVs and human driven vehicles alike. In prior work by the Institute of Automated Mobility (IAM), operational safety metrics were introduced as part of an operational safety assessment (OSA) methodology that provide quantification of behavioral safety of AVs and human-driven vehicles as they interact with each other and other road users. To calculate OSA metrics, the data capture system must accurately and precisely determine position, velocity, acceleration, and geometrical relationships between various safety-critical traffic participants. The design of an infrastructure-based system that is intended to capture the data required for calculation of OSA metrics is addressed in this paper.
Technical Paper

Assessing the Impacts of Dedicated CAV Lanes in a Connected Environment: An Application of Intelligent Transport Systems in Corktown, Michigan

2021-04-06
2021-01-0177
The interaction of Connect and Automated vehicles (CAV) with regular vehicles in the traffic stream has been extensively researched. Most studies, however, focus on calibrating driver behavior models for CAVs based on various levels of automation and driver aggressiveness. Other related studies largely focus on the coordination of CAVs and infrastructure like traffic signals to optimize traffic. However, the effects of different strategic flow management of CAVs in the traffic stream in the comparative scenario-based analysis is understudied. Thus, this study develops a framework and simulations for integrating CAVs in a corridor section. We developed a calibrated model with CAVs for a corridor section in Corktown, Michigan, and simulate how dedicated CAV lane operations can be implemented without significant change in existing infrastructure.
Technical Paper

Impact of Lateral Alignment for Cooling Airflow during Heavy-Truck Platooning

2021-04-06
2021-01-0231
A truck platooning system was tested using two heavy-duty tractor-trailer trucks on a closed test track to investigate the thermal control/heat rejection system sensitivity to intentional lateral offsets over a range of intervehicle spacings. Previous studies have shown the following vehicle can experience elevated temperatures and reduced airflow through the cooling package as a result of close-formation platooning. Four anemometers positioned across the grille of the following trucks as well as aligned and multiple offset positions are used to evaluate the sensitivity of the impact. Straight sections of the track are isolated for the most accurate airflow impact measurements and to be most representative of on-highway driving. An intentional lateral offset in truck platooning is considered as a controls approach to mitigate reduced cooling efficacy at close following scenarios where the highest platoon savings are achieved.
Technical Paper

An Optimized Design of Multi-Chamber Perforated Resonators to Attenuate Turbocharged Intake System Noise

2021-04-06
2021-01-0669
The turbocharger air intake noise during transient conditions like wide open throttle and tip-in/out affects the passenger ride comfort. This paper aims to study an optimized design of multi-chamber perforated resonators to attenuate this noise. The noise produced by a turbocharger in a test vehicle has been measured to find out the noise spectral characteristics which can be used to design the acoustic targets including the amplitude and frequency range of transmission loss (TL). The structural parameters of the resonators are optimized based on genetic algorithm (GA) and two-dimensional prediction theory of the resonator TL. The optimized resonators are installed on the test vehicle to verify the actual noise reduction effect. The results suggest that the broadband noise has been eliminated, and subjective feelings are greatly improved.
Technical Paper

Automated Highway Overtaking: A Perspective from Decision-Making

2021-04-06
2021-01-0127
This paper presents a comprehensive decision-making algorithm for highway overtaking maneuvers, one of the highest risk maneuvers. For such, an overtaking scenario is divided into four phases: approach phase in which the host or overtaking vehicle (HV) detects a slow-moving lead vehicle (LV) in the same lane; left lane change and passing phase in which the HV performs a left lane change and passes the LV; right lane change phase in which the HV comes back to its original lane and free-flowing phase in which the HV maintains its lane and the initially set velocity. Depending on the phase-wise safety zones, the decision-making algorithm makes two decisions: change lane (1 = left lane change, 0 = maintain the same lane, -1 = right lane change) and adjust speed (1 = accelerate, 0 = maintain the current speed, -1 = decelerate). The proposed decision-making algorithm complements the human driver’s decision-making process and can be easily adapted for individual users.
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