Browse Topic: Reaction and response times

Items (469)
Find
Human-AI Interaction in Autonomous Medical Evacuation HelicoptersF-0081-2025-02825/20/2025
The vertical flight industry is on its way to a transformative era, with autonomous technologies set to alter aerial vehicle operations. While it seems certain that fully autonomous helicopters will eventually be deployed for a variety of missions, some high-stakes situations—like medical evacuations (MEDEVAC)—will for the foreseeable future demand human participation in the form of Emergency Medical Care-giving Crew. This study describes the testbed built to run and investigate hypothetical future situations in which a helicopter is autonomously piloted while a human medic with no aviation training, subjected to aviation and medical emergencies, manages patient care onboard. A total of 22 participants, with emergency medical technician certification, nursing or a medical board certification, were invited to run and evaluate the use of AI pilot (AP) in different scenarios of medical evacuation under the following emergencies: medical, empty fuel tank, pressure sensor miscalibration, and engine failure. A comprehensive evaluation of both objective and subjective performance metrics revealed that novice medical professionals could effectively execute medical evacuation operations in conjunction with an AI pilot, even during unforeseen circumstances. The analysis of response times unveiled distinct perspectives on how medics perceive and manage various emergency situations when an AP functions as a collaborative and effective team member.
Doda, Sanya, Feigh, Karen, Agbeyibor, Richard, Cortes, Carmen, Kolb, Jack, Magalhaes, Jose
Optimizing Comprehension and Performance in Technical Documentation: Does Adding Multimedia to Written Instructions Help to Safely and Accurately Perform Maintenance Tasks?F-0081-2025-01445/20/2025
As part of a human factors research project aimed at optimizing technical documentation used in helicopter maintenance with multimedia elements, we compared different instruction formats to observe their effects on the performance of an assembly task. This task offers us the opportunity to test procedures that call for similar actions as a maintenance task (e.g., localization, action sequencing, assembly). Static (i.e., image and image with text) and dynamic instruction formats (i.e., video, video with text and video with audio) were compared to determine if dynamic formats allowed a better motor performance of the task for assembly reaction time (time needed to complete the assembly) and accuracy. We were also interested in how the use of the text instructions interacted with both visual dynamic and static instructions. Reaction times were recorded and measured with eye tracking data. Subjective data was collected in questionnaires during and after the experiment. Results showed significant differences in the time spent on the instructions and the time spent on the assembly, depending on the format of instructions. Overall, assembly time is shorter with video instruction formats, but videos took longer to be consulted than static formats. Results also showed a difference in the number of actions required to do the assembly. Videos facilitated the right path of action sequence in comparison with static formats. With the analysis of both subjective and objective data, the results give us a better idea of the advantages and drawbacks of using dynamic formats in technical documentation.
Faye, Myriam, Jahchan, Nataly, Condamines, Anne, Amadieu, Franck
Driver Drowsiness and Fatigue in the Safe Operation of Vehicles - Definition of Terms and ConceptsJ3198_202010 (Current)10/26/2020
This SAE Information Report provides definitions and discussions of key terms concerning driver drowsiness and fatigue, and basic information on measuring drowsiness and fatigue. It also includes information and concepts for driver drowsiness as they relate to the safe operation of a vehicle. The key driver drowsiness and fatigue causal factors include the following: (1) sleep quality and quantity, (2) time of day, (3) time awake, (4) time on task (modulated by characteristics of the driving task), (5) task-related fatigue (variations of arousal levels related to task underload and overload), and (6) combinations of these factors. Medical conditions, medication, alcohol, or drugs exacerbate drowsiness; however, the discussion in this report is limited to fatigue concepts. This report has two primary outputs: (1) definitions and discussions of key terms concerning driver drowsiness and fatigue, and (2) basic information on measuring drowsiness and fatigue and its effects on the safe operation of a vehicle. These include the physiological and cognitive effects of driver drowsiness and fatigue on driving safety. Examples of effect of driver drowsiness and fatigue on driving safety include those related to vehicle control, operator vigilance (sustained attention), reaction times (object and event detection and response), situational awareness, physiological indicators, subjective assessments, and combinations thereof. For definitions of driving performance measures, refer to SAE J2944. This report applies to all worldwide motor vehicle passenger cars and light trucks, as well as heavy trucks, buses, motorcycles, and mopeds. The intended users of the document are practitioners and researchers in the automotive industry, academia, and other organizations with interest in driver drowsiness and fatigue, driving and driver performance assessment, and road safety.
Driver Metrics, Performance, Behaviors and States Committee
Influence of Optical and Gravito-Inertial Cues to Height Perception During Supervisory ControlF-0076-2020-1641710/5/2020
Future vertical lift (FVL) missions will be characterized by increased agility, degraded visual environments (DVE) and optionally piloted vehicles (OPVs). Increased agility will induce more frequent variations of linear and angular accelerations, while DVE will reduce the structure and quality of the out-the-window (OTW) scene (i.e. optical flow). As helicopters become faster and more agile, pilots are expected to navigate at low altitudes while traveling at high speeds. In nap of the earth (NOE) flights, the perception of self-position and orientation provided by visual, vestibular, and proprioceptive cues can vary from moment to moment due to visibility conditions and body alignment as a response to gravitoinertial forces and internally/externally induced perturbations. As a result, erroneous perceptions of the self and the environment can arise, leading ultimately to spatial disorientation (SD). In OPV conditions, the use of different autopilot modes implies a modification of pilot role from active pilot to systems supervisor. This shift in paradigm, where pilotage is not the primary task, and where feedback from the controls is no more available, is not without consequences. Of importance is the evidence that space perception and its geometric properties can be strongly modulated by the active or passive nature of the displacement in space. An experiment was conducted using the vertical motion simulator (VMS) at the NASA Ames Research Center that examined the contributions of gravitoinertial cueing and visual cueing in a task where the pilot was not in control of the aircraft but was asked to perform altitude monitoring in a simulated UH-60 Black Hawk helicopter with a simulated autopilot (AP) mode. Within the altitude monitoring task, the global optical density (OD), flow rate and visual level of detail (LOD) were manipulated by the introduction of an 18ft vertical drift, upward or downward that simulates a vertical wind shift. Seven pilots were tested in two visual meteorological conditions, good visual environment (GVE) and degraded visual environment (DVE) and two gravitoinertial conditions, where platform motion was either ON or OFF. The results showed that both the good quality of the visual environment and the presence of gravitoinertial cues improved altitude awareness and reduced detection/ reaction times. The improvement of the tracking performance in the visuo-vestibular setting as compared to a visual only setting when the visual cues were poor indicated some level of multisensory integration. Task-dependent limitations of a popular aeronautics metric called DIMSS-PM (Dynamic Interface Modeling and Simulation System Product Metric) and its sub-components were shown, and recommendations for OPV operations were formulated.
Godfroy-Cooper, Dr., Denquin, Francois, Bachelder, Dr., Miller, Joel, Jean, Dr.
Development of Design and Engineering Recommendations for In-Vehicle Alphanumeric MessagesJ2831_202007 (Current)7/29/2020
This Information Report provides recommendations for alphanumeric messages that are supplied to the vehicle by external (e.g., RDS, satellite radio) or internal (e.g., infotainment system) sources while the vehicle is in-motion. Information/design recommendations contained in this report apply to OEM (embedded) and aftermarket systems. Ergonomic issues with regard to display characteristics (e.g., viewing angle, brightness, contrast, font design, etc.) should review ISO 15008.
Driver Vehicle Interface (DVI) Committee
The Effect of An Acoustic Startling Warning On Take-Over Reaction Time And Trunk Kinematics for Drivers in Autonomous Driving Scenarios2019-22-00223/31/2020
The Acoustic Startling Pre-stimulus (ASPS, i.e. a loud sound preceding a physical perturbation) was previously found to accelerate action execution in simple flexion exercises. Therefore in this study we examined if ASPS can accelerate take-over reaction times in restrained teen and adult drivers who were asked to reach for the steering wheel while experiencing sled lateral perturbations simulating a vehicle swerve. Results showed that adult drivers lift their hands toward the steering wheel faster with the ASPS versus without (161 ± 23 ms vs 216 ± 27 ms, p<0.003). However this effect was not found in teens or in trials where the drivers were engaged in a secondary task. Adults also showed reduced lateral trunk displacement out of the seat belt with the ASPS. The ASPS could represent a novel warning that reduces take over time and out-of-position movements in critical autonomous driving scenarios.
Graci, Valentina, Griffith, Madeline, Maheshwari, Jalaj, Akkem, Rahul, Austin, Meta, Seacrist, Thomas, Arbogast, Kristy B.
The 6 Most Important Parts of a Temperature Monitoring SystemTBMG-3546211/1/2019
In the past few years, it has become increasingly common for hospitals, clinics, healthcare and life science organizations, and other businesses to use an electronic temperature monitoring system to safeguard their products and satisfy regulatory demands. You may know that you need a monitoring system, possibly with alarming capabilities, but aren't sure how to select the best one to meet your needs. To complicate matters, there are literally dozens of different types of temperature monitoring systems with different features and a wide range of prices.
Fiber-Based Artificial MusclesTBMG-351329/1/2019
While different approaches have been used to create artificial muscles — including hydraulic systems, servomotors, shape-memory metals, and polymers that respond to stimuli — they all have limitations such as high weight or slow response times. A fiber-based system was developed that is extremely lightweight and can respond very quickly.
Organic Semiconductor Thin-Film Sensors Detect Disease Markers in BreathTBMG-348958/1/2019
Organic semiconductors (OSCs) have emerged as a new class of electronic materials promising a wide range of applications including organic field-effect transistors (OFET), solar cells, thermoelectrics, electronic skins, and chemical and mechanical sensors by virtue of their chemical versatility, solution processability, and mechanical flexibility.
German University Studying Assisted-Driving ‘Handoff’19AVEP07_087/1/2019
Germany's Kempten University Adrive Living Lab will feature latest aVDS driving simulator to research ADAS stress levels. Researchers at Germany's Kempten University of Applied Sciences plan to embark this year on autonomous vehicle (AV) and advanced driver-assist system (ADAS) programs that will include investigation of the safest ways to achieve handover of a vehicle when control is returned to a human driver. To do so, it is installing an AB Dynamics advanced Vehicle Driving Simulator (aVDS) that will help measure driver stress levels if the vehicle is not capable of performing a particular maneuver. The aVDS has been designed to provide high level R&D capabilities specifically for autonomous systems. The university has established its Adrive Living Lab with the third-generation simulator helping to facilitate the study of the driver's interaction with autonomous systems and their effect on drivers' perceived safety and comfort. The program has identified these two areas as the most important for consumer acceptance and enthusiasm.
Birch, Stuart
When You Need a Machine for Breathing, You’d Better Have Accurate SensorsTBMG-345916/1/2019
Medical ventilation technology has come far since the original iron lung was first used more than 90 years ago. Using negative pressure to ventilate, the patient was inserted into an airtight chamber looking like a prop from a Sci-Fi movie. The iron lung mimicked the physiological act of breathing. Pumps controlling airflow periodically increased and decreased air pressure within the chamber and thus indirectly in the patient’s chest. Lungs were inflated by applying negative pressure to the patient’s body and then when the pressure inside the chamber increased, it compressed the patient’s chest and forced them to exhale. But the machines were bulky and restricted a patient’s ability to move. So, when positive pressure ventilators were developed in the 1950s, the technology caught on. Patients were not restricted, and caregivers could better examine them. Modern ventilators use either a tracheal tube or mask to apply positive pressure and inflate the lung during inspiration.
High Tech Comes to Fitness MonitoringTBMG-345826/1/2019
Early wearable fitness monitoring devices were designed to perform a set of valuable but straightforward activities: tallying the number of steps we take daily, recording the number of hours we sleep, and monitoring our heart rate.
Driver Behavior in Left Turn across Path from Opposite Direction Crash and near Crash Events from SHRP2 Naturalistic Driving2019-01-04144/2/2019
The turn-across-path from opposite-direction [LTAP-OD] crash type contributes to one of the major fatal crash types in young drivers. Drivers responses in police reportable and severe crashes and near crashes involving an LTAP-OD scenario were evaluated from query of the Second Strategic Highway Research Program [SHRP-2]. This research examined the responses of through drivers. 122 such events were analyzed to extract driver braking behavior, secondary tasks, age, and perception-response times. All measures of through driver variables were compared with respect to turning driver behavior. The study aimed to identify the trigger event for drivers to respond to the left turning vehicle. Time to contact was a significant factor which affected driver response times. Drivers responded significantly faster when subjected to shorter time to contact events compared to longer ones. Other short time to contact events included when the turning vehicle did not stop before entering the intersection, or when the turning vehicle was visible for a short duration. Driver factors such as age, gender or secondary task engagement did not significantly influence response times.
Dinakar, Swaroop, Muttart, Jeffrey
Automated Vehicle Disengagement Reaction Time Compared to Human Brake Reaction Time in Both Automobile and Motorcycle Operation2019-01-10104/2/2019
Autonomous Vehicle Disengagement Reports have been published by the California Department of Motor Vehicles since 2015. The State of California autonomous vehicle testing regulations require every manufacturer authorized to test autonomous vehicles on public roads to submit an annual report summarizing disengagements. In early versions of the annual report, automated vehicle manufacturers were required to provide the time that it took for a human driver to take manual control of the vehicle when reporting vehicle disengagements. This study analyzes reported automated vehicle disengagement reaction times from 2015 through 2017 for various manufacturers that provided information to the California Department of Motor Vehicles while operating vehicles in autonomous mode. This study compares the reported automated vehicle operation disengagement reaction time to field literature in testing and experimentation on human brake reaction times for both automobile and motorcycle operation.
Dinges, Jeffrey T., Durisek, Nicholas J.
Learning from Human Naturalistic Driving Behavior at Stop Signs for Autonomous Vehicles2019-01-10214/2/2019
Despite public expectations that autonomous vehicles should be able to avoid most accidents, the existing fleet of autonomous test vehicles has demonstrated this is simply not the case. An explanation for some of these accidents has been that these vehicles do not drive like humans and therefore do not exhibit certain driving patterns expected by human drivers. With the high likelihood of a gradual integration of autonomous vehicles into our traffic system in the future, there will be a need for such vehicles to adapt to, and mimic, human driving. Although much work has been done to understand human behavior and performance in driving, it has been mostly geared towards defining human capabilities and limitations. Little work has been done on the interactions between human-driven and autonomous vehicles. In previously published work, we described a large-scale, on-road eye tracking study conducted in instrumented test vehicles to understand and assess human behavior in a naturalistic driving environment. Here we describe one condition from that study, approaching and proceeding through stop-sign-controlled intersections, in the context of applying our work to the development of autonomous vehicles. We investigated naturalistic driver behavior at stop signs based on vehicle dynamics. In particular, we obtained deceleration rates, stopping/slowing speeds, stopping/slowing durations and acceleration rates while participants drove specific routes in Los Angeles. We also found and quantified clear evidence of “California Rolls” for many drivers. We suggest that data such as that presented in this paper can be incorporated into autonomous systems such that they behave more like human drivers (e.g. to avoid rear-end accidents), as well as to better predict human driving behaviors (e.g. “California Rolls” and very short stops).
Tavassoli, Abtine, Cymbalist, Niccolo, Dunning, Amber, Krauss, David
The Kinematic Analysis of Occupant Excursions and Accelerations during Staged Low Speed Far-Side Lateral Vehicle-to-Vehicle Impacts2019-01-10304/2/2019
The collection of research regarding occupant kinematics during low speed lateral vehicle-to-vehicle impacts is far less comprehensive than the much larger body of literature that quantifies the occupant kinematics associated with low speed rear end (longitudinal) impacts. In order to augment the available data, a series of 39 low speed far-side lateral vehicle-to-vehicle impacts were conducted in a laboratory setting. A combination of accelerometers and 3D motion tracking was used to characterize the motions of both the Target and Bullet vehicles during their collisions. The Target vehicle was initially stationary; the Bullet vehicle impacted the Target vehicle at the front passenger side door. The Bullet vehicle pre-impact speeds across all tests ranged from approximately 2.5 to 5.5 mph (4.0 to 8.9 kph; 1.1 to 2.5 m/s). Eight volunteers participated in the study. Volunteers were seated in the driver seat during the impacts and were outfitted with accelerometers on their head and wore reflective markers for 3D motion tracking on the left side of their body. The experimental design included conducting lateral impacts while the volunteers were in both “non-distracted” and “distracted” states to identify any potential influence on occupant kinematics. In addition, effects of gender and anthropometry were explored. Primary outcome measures that were analyzed for each lateral impact included occupant accelerations measured at the head and the lateral displacement of the head relative to its initial position prior to impact. Volunteer peak resultant head accelerations (including gravity) ranged from 1.90 to 4.32 g. The peak Y-axis displacement of the head relative to the Target vehicle and away from the driver side B-pillar was 3.86 to 12.16 inches (9.80 to 30.89 cm) while the peak Y-axis displacement of the head relative to the Target vehicle and toward the driver side B-pillar ranged from 0.02 to 7.34 inches (0.05 to 18.64 cm). In all trials, the head displacement toward the driver side B-pillar was insufficient to cause physical contact.
Shibata, Peggy, Roberts, Julius, Sprague, James, Light, Alyson, Stegemann, Jacob, Meza-Arroyo, Manuel, Capser, Shawn
An Examination of Comfort and Sensation for Manual and Automatic Controls of the Vehicle HVAC System2019-01-50051/15/2019
The fast-changing and asymmetrical nature of the cabin environment challenges climate control systems in maintaining occupant comfort. This article examines the relationship between the control that occupants have over the heating, ventilation, and air conditioning (HVAC) system and their perceived comfort within the surrounding thermal environment. Three test cases using automatic control (20°C, 22°C, 24°C) and one in manual mode were evaluated via driving trials under normal road conditions in the United Kingdom during winter. In these trials, car cabin occupants felt more comfortable when using manual control than automatic (Fisher’s test, p = 2.2 × 10−16). Occupants felt neutral thermal sensations at head and foot level when using manual control. At chest level, occupants felt thermally neutral for both automatic and manual controls. This research highlights the need for further exploration of the interaction of the cabin occupants with their HVAC systems and the impact it has on their comfort perception.
Petre, Alexandra Galina, Brusey, James, Wilkins, Ross
Simulation Techniques for Determining Motorcycle Controllability Class according to ISO 262622018-32-006010/30/2018
The ISO 26262 standard specifies the requirement for functional safety of electrical and electronic systems within road vehicles. We have accumulated case studies based on actual riding tests by subjective judgment of expert riders to define a method for determining the controllability class (C class). However, the wide variety of practical traffic environments and vehicle behaviors in case of malfunction make it difficult to evaluate all C classes in actual running tests. Furthermore, under some conditions, actual riding tests may cause unacceptable risks to test riders. In Part 12 Annex C of ISO/DIS 26262, simulation is cited as an example of a technique for comprehensive evaluations by the Controllability Classification Panel. This study investigated the usefulness of mathematical simulations for evaluating the C class of a motorcycle reproducing a malfunction in either the front or rear brakes. To estimate the rate of rate of successful harm avoidance in this scenario, which is considered useful in judging the C class, we calculated whether a representative rider can stop while leaving a safe distance to a hazardous object. For the calculations, we used time-series waveforms of the brake actuation force described by parameters such as the brake reaction time and the maximum brake actuation force. These parameters were chosen from the data that riders’ compensatory control actions were recorded during the actual riding tests. The rates of successful harm avoidance obtained from the calculations showed the almost same tendency as the results of the actual riding tests. This agreement indicated the rate of successful harm avoidance can be estimated with simulations that use brake operation waveforms to model the compensatory control action.
Kawakoshi, Maki, Kobayashi, Takashi, Hasegawa, Makoto
Correlation of Objective and Subjective Evaluation in Automotive Brake Pedal Feel2018-01-188910/5/2018
In order to establish the correlation between objective and subjective evaluation of brake pedal feel for passenger cars, road tests of brake pedal feel were carried out and an evaluation method was proposed. In the road tests, subjective scores and objective measurements were obtained under the conditions of uniform and emergency braking. The objective measurements include pedal preload, low deceleration pedal force and travel, moderate deceleration pedal force and travel, brake response time and brake linearity. Using the theory of analytic hierarchy process (AHP), the design process of the evaluation method was established. Key setups including the hierarchical structure model, the judgement matrix and the score calculation method of objective measurements were described in detail. Then, the correlation between subjective and objective scores was analyzed. It can be concluded that the evaluation method is effective and it can be applied to brake pedal feel assessment and adjustment.
Zhang, Jingyi, Meng, Dejian, Liu, Jialin
Modeling Response Time of Next Generation Electric Brake Boosters2018-01-187110/5/2018
In the course of this paper, a model suitable for studying the performance - in terms of response time, current draw, and peak pressure capacity - of an electric booster-based brake system is introduced. Some discussion about the need the model is attempting to fulfill and how it fits into the vehicle development process is offered, before explaining the model in full. The equations describing the physics of the model are presented, and an explanation of how the elements of the model are integrated together into an easy to use, fast-running spreadsheet environment is given. Case study examples, validating the model against physical test (hardware in the loop) test results are shown, followed by sensitivity studies testing how changing parameters such as caliper Pressure-Volume curves, hydraulic system flow characteristics, voltage supply, and temperature conditions affect performance.
Antanaitis, David B.
A Paper-Like LCD — Thin, Flexible, Tough, and CheapTBMG-328809/1/2018
Optoelectronic engineers in China and Hong Kong have manufactured a special type of liquid crystal display (LCD) that is paper-thin, flexible, light, and tough. With this, a daily newspaper could be uploaded onto a flexible paper-like display that could be updated as fast as the news cycles. It sounds like something from the future, but scientists estimate it will be cheap to produce, perhaps only costing $5 for a 5-inch screen.
SPECIAL REPORT: MEDINNOVATION BOSTON 2018TBMG-328199/1/2018
The medical device industry is built on innovation and invention. They are the drivers of change and evolution in this industry. But bringing these emerging technologies to market can be challenging. In June 2018, MEDInnovation Boston, jointly presented by Medical Design Briefs and MDG Boston, brought together leaders from across industry to share their insights and expertise. Below are just a few highlights and ideas from some of those experts.
Real-Time Ultraflexible Sensor Improves Inflammation TestingTBMG-338519/1/2018
The University of Hong Kong Hong Kong
Research on the Development Trend of Brain Controlled Cars2018-01-15878/7/2018
This paper studies the development trend of the brain controlled cars. A brain controlled car is a new application of the brain-computer interface (BCI) to the on-road motor vehicles. As a new frontier science, the relevant studies are exploratory and still at an early stage. The prospect of the brain controlled cars is also unclear. In this paper, we summarizes the research status of the brain controlled cars based on both the academic articles and publicly released demo cars. The research history, the achievable control functions, the vehicle types that implemented on, the testing scenarios and the technology roadmaps are elaborated. According to the development traces of both the intelligent connected vehicle (ICV) and the artificial intelligence (AI) technologies, we predicted the development trend of the brain controlled cars. This paper is from a novel angel that considering BCI technology as one of the driver assistance methods to make the driving experience more intelligent, more safe and reliable, more comfortable, and more compliant to the driver’s intention. The main finding of this paper is that human-computer collaborative driving by the hybrid-augmented intelligence is the irresistible trend of the brain controlled cars. The hybrid-augmented intelligence will mainly act on the environment perception module, the decision-making & planning module and the control & execution module of an autonomous driving car to achieve the full autonomous driving in the open traffic and maximally ensure the driving safety. Additionally, applying BCI technology to the human-computer interface (HMI) in a car makes the driving experiences more “people oriented”. This paper plays a positive role in promoting the applications of BCI technology to the on-road motor vehicles, accelerating the development of ICV, as well as improving our future driving experiences.
Bie, Weiwei, Li, Kai, Zhang, RuiLin, Huang, Yi, Fang, Qiang, Hu, Jin, Qian, Jianshu
Near-Zero-Power Temperature SensorTBMG-296847/1/2018
A temperature sensor was developed that runs on 113 picowatts of power — about 10 billion times smaller than a Watt. The technology could enable devices that can be powered by harvesting energy from low-power sources, such as the body or the surrounding environment. Potentially, the system could run for years on a tiny battery.
Emergency Autonomous to Manual Takeover in a Driving Simulator: Teen vs. Adult Drivers – A Pilot Study2018-01-04994/3/2018
Autonomous and/or automated vehicles offer a host of future opportunities but leave many questions unanswered regarding their impact on crash avoidance or the ability of drivers to effectively scan and re-engage from self-driving mode when necessary to avoid crash scenarios. Considering a 16-year-old is several times more likely to die in an automobile crash than other licensed drivers, it was crucial to test both teenage drivers and adults to determine head-on collision avoidance abilities when subjected to a failing autopilot in a simulated autonomous vehicle. In this study, eight teenagers ages 16-19 and four experienced adults underwent four simulated drives (one manual practice drive and three simulated autonomous drives) using a hi-fidelity, Real Time Technologies SimDriver Simulator to represent being in a self-driving vehicle. When exposed to a head-on crash event where the opposing vehicle crosses the dividing line and drives towards the subject, most subjects successfully swerved to avoid the car albeit with several oscillations before stabilization.
Belwadi, Aditya, Loeb, Helen, Shen, Michelle, Shaikh, Saniyah, Ward McIntosh, Chelsea
Design and Development of Active On-Board Alcohol Detection System with Safety Features for Commercial Vehicles2018-01-06024/3/2018
Drink & drive has caused the increased rate of commercial vehicle accidents in the world due to the slow response to judgment and reasoning. According to research study 70% accidents are happened due to drunk & drive, it causes loss of human life and economic damage. Research has proven that drunk drivers exhibit aggressive driving behavior and apply more force during braking. While public health awareness and legal restrictions can assist in educating and discouraging people from drunk & drive, a more fool-proof method is not available in the market for commercial vehicles. Currently, a low cost, fail-safe onboard alcohol detection, and vehicle safety system is the need of the hour. This paper deals with the design & development of a low cost active onboard breath alcohol detection system and it’s on vehicle validation. Further, it explains the type of alcohol detection sensor used, controller design, logic programming and system packaging. An accurate, precise and contactless alcohol detection system and advanced safety features are the key highlights. The system has been validated on the vehicle, to check the response time & alcohol detection accuracy of the sensor, the preciseness of sensor location and safety features. Safety feature include SMS & voice call based alerts, sharing of vehicle geographical location and audio warnings inside the cabin and vehicle control features such as vehicle engine auto cut off in a stationary condition for disabling vehicle cranking and in case of moving vehicle gradually reducing engine torque to stop the vehicle. Good alcohol detection accuracy and system response time has been demonstrated in the validation of the drunk subjects.
Bakatwar, Rupesh, Yaser, K U Syed Taj, Jadhav, Sourabh, Bhargava, Aashish
Research of Steering Grasping to Take over Driver from System2018-01-10684/3/2018
Lane departure prevention systems are able to detect imminent departure from the road, allowing the driver to apply control to prevent lane departure. These systems possess enormous potential to reduce the number of accidents resulting from road departure, but their effectiveness is highly reliant on their level of acceptance by drivers. The effectiveness of the systems will depend on when they are providing driving assistance, what level of laxness in terms of maintaining contact with the steering wheel is allowed on the part of the driver, and what level of assistance the system provides. This paper will discuss research on the minimum necessary contact and contact strength with the steering wheel on the part of the driver when a lane departure prevention system is in operation. Using a six-axis driving simulator employing an actual vehicle, the research conducted tests involving 22 test subjects, and studied the relationship between the status of the driver’s contact with the steering wheel and vehicle behavior when the system failed. As a result of simulation, when the driver had relinquished steering control and the vehicle was self-steering on the curve, contact of even one finger with the steering wheel made the reaction time faster.
Odate, Shotaro, Fujimaki, Takeshi, Sakamoto, Naohiro
Driver Response Time to Cyclist Path Intrusions2018-01-05314/3/2018
Motor vehicle crashes with cyclists are on the rise, with a six percent increase in fatal crashes from 2006 to 2015 in the USA. Although some research exists on the response time of drivers to some types of path intrusions, data on the perception-response of through drivers to cyclists who fail to stop at a stop sign, and ride into the path of the vehicle has not been researched. The purpose of this study was to quantify the Driver Response Time (DRT) to a cyclist that intrudes perpendicularly in front of a through vehicle at an intersection where the driver has the right-of-way. The DRT was measured from when the cyclist is positioned at the stop sign until the driver reacts, whether by touching the brake pedal, swerving (steering wheel angle change of at least 2 degrees), accelerating, or a combination of those responses. 26 (NFemale = 13; NMale = 13) university aged licensed volunteer drivers participated in the study conducted at the University of Guelph Driving Research in Virtual Environments (DRiVE) lab using an Oktal complete vehicle driving simulator. After a brief practice drive to acclimatize to the virtual environment, participants completed the approximately 10 minute experiment drive during which the cyclist hazard was presented. About one quarter of drivers crashed into the cyclist, with a mean time-to-impact of 3.26 seconds. There were no gender differences in terms of DRT or collision rates.
Toxopeus, Ryan, Attalla, Shady, Kodsi, Sam, Oliver, Michele
Utilization of Perceptual Looming in Overtaking Decisions2018-01-05014/3/2018
This paper presents the results of a naturalistic study of driver’s responses to a slower moving vehicle. The objectives of the study were to determine if drivers utilize perceptual looming when electing to pass a slower moving vehicle and if so, the degree to which the looming value corresponds to the findings from controlled studies of driver’s ability to detect perceptual looming. The results indicate that drivers do rely on perceptual looming as a cue when initiating a passing maneuver and that the associated value is consistent with findings from controlled studies of driver’s abilities in this regard.
Edwards, Mark L., Stewart, Christopher, Fiorenze, Robert
Driver Response Time to Midblock Crossing Pedestrians2018-01-05144/3/2018
Vehicle-pedestrian collisions account for 15% of fatal crashes in the USA, and there has been a twelve percent increase in fatal crashes in the USA from 2006 to 2015. Although research exists on the response time of drivers responding to pedestrian path intrusions, data on the response time of through drivers to jaywalking pedestrians crossing from the far side of the road has not been determined. Therefore, the purpose of this study was to quantify Driver Response Time (DRT) to a pedestrian that intrudes perpendicularly into the path of a vehicle from the far curb (adjacent to oncoming traffic). 50 (NFemale = 25; NMale = 25) licensed volunteer drivers took part in a study at the University of Guelph Driving Research in Virtual Environments (DRiVE) lab using an Oktal complete vehicle driving simulator. After a brief practice drive to acclimatize to the virtual environment, participants completed the approximately 10 minute experiment drive during which the pedestrian hazard was presented. Only eight percent of drivers collided with the pedestrian with a mean time-to-impact of 4.35 seconds. There were no gender differences in terms of DRT or crash rate.
Toxopeus, Ryan, Attalla, Shady, Kodsi, Sam, Oliver, Michele
Driving Characteristics when Autonomous Driving Change to Driver in Low Alertness and Awake from Sleeping2018-01-10814/3/2018
Two experiments were carried out to clarify the characteristics of manual driving when the task of vehicle control is transferred from an autonomous driving system at SAE levels 3 and 5 to manual driving. The first experiment involved another vehicle merging into the lane of the host vehicle from the left side of a highway. This experiment simulated the functional limit of a level 3 system with the driver in a situation of low alertness. When the other vehicle changed lane in front of the host vehicle, the driving task was transferred from the system to the driver. The second experiment simulated a driver travelling along a city road with manual driving after the driver used the system in a situation of sleeping on a highway. In this experiment, a pedestrian emerges from a blind spot along a city road, and the driver needs to brake having recently awaken. In the first experiment, the driver with low alertness could not control the vehicle when manually driving. In the second experiment, the driver took a long time to deploy the brake and could not properly operate the brake pedal. There are two main results of this research. (1) The autonomous driving system has to detect the driver’s situation and activate a warning that notifies the driver of the change in the driving task (level 3). (2) If the driver uses the system in a situation of sleep, manual driving is possible only after the driver wakes completely (level 5).
Gokan, Masato, Yamaguchi, Daisuke, Hirose, Toshiya
Effect of Driver Posture on Driving Characteristics when Control is Passed from an Autonomous Driving System to a Human Driver2018-01-11734/3/2018
SAE International defines six levels of autonomous driving system, four of which include a change of control from the system to the driver in certain conditions. When vehicle control changes from the system to a human driver, a safe transition time is necessary. The present study focuses on level 3 automation, in which the system controls driving in ordinary conditions, but the human driver is expected to intervene in emergency situations. The aim of this study was to investigate the relationship between driver posture and transition time. Driver posture included four components: backrest angle, seat position, foot position, and arm position. These were adjusted to investigate a total of 30 posture patterns. In addition, the situation in which the driver was not watching the road, but instead using a tablet computer was investigated. The driver’s braking and steering reaction times were measured for a highway-driving scenario in which a truck dropped cargo in front of the vehicle. Acoustic and optical warnings were presented to the driver when the autonomous driving system was disengaging. The results showed that the driver’s foot position most strongly affected braking reaction time. The driver resting their chin on their hands most strongly affected steering reaction time. This research clarified the effect of relaxed driver posture on reaction time and, thus, transition time.
Suzuki, Kensuke, Gokan, Masato, Oikawa, Shoko, Matsui, Yasuhiro, Hirose, Toshiya
The Effect of In-Cylinder Temperature on the Ignition Initiation Location of a Pre-Chamber Generated Hot Turbulent Jet2018-01-01844/3/2018
Ignition location is one of the important factors that affect the thermal efficiency, exhaust emissions and knock sensitivity in premixed-charge ignition engines. However, the ignition initiation locations of pre-chamber generated turbulent jet ignition, which is a promising ignition enhancement method, are not clearly understood due to the complex physics behind it. Motivated by this, the ignition initiation location of a transient turbulent jet in a constant volume combustor is analyzed by the use of computational fluid dynamics (CFD) simulations. In the CFD simulations of this work, commercial codes KIVA-3 V release 2 and an in-house-developed chemical solver with a detailed mechanism for H2/air mixtures are used. Comparisons are performed between simulated and experimental ignition initiation locations, and they agree well with one another. A detailed parametric study of the influence of in-cylinder temperature on the ignition initiation location is also performed. As the temperature increases, the ignition initiation location significantly moves toward the exit of the orifice. When the mixture reaches the temperatures of 600 and 700 K, large amounts of OH and H radicals are observed in the orifice exit zone. The chemical reaction time scales decrease with increasing temperature, leading to a short time duration requirement for the reactant consumption for high temperature cases. In addition, low stream-wise Damköhler number zone shortens with rising temperature, and ignition occurs within zones where Damköhler number is close to one. These results demonstrate that the increase of temperature causes the reduction of chemical reaction time scales, and in turn leads to ignition initiation location moving upstream from the jet where mixing is high.
Wang, Nana, Liu, Jinxiang, Chang, Wayne, Lee, Chia-Fon
Near-Zero-Power Temperature SensorTBMG-285303/1/2018
A temperature sensor was developed that runs on 113 picowatts of power — about 10 billion times smaller than a Watt. The technology could enable devices that can be powered by harvesting energy from low-power sources, such as the body or the surrounding environment. Potentially, the system could run for years on a tiny battery.
Transfer Technique Produces Wearable Gallium Nitride Gas SensorsTBMG-281221/1/2018
A transfer technique based on thin sacrificial layers of boron nitride could allow high-performance gallium nitride gas sensors to be grown on sapphire substrates and then transferred to metallic or flexible polymer support materials. The technique could facilitate the production of low-cost wearable, mobile, and disposable sensing devices for a wide range of environmental applications.
Single Photon Camera Offers High Speed and High ResolutionTBMG-281271/1/2018
Photon counting detectors with high spatiotemporal resolution are key tools of imaging techniques where picosecond timing and micrometer position imaging are required, such as time correlated single photon counting (TCSPC) or fluorescence lifetime imaging microscopy (FLIM) where fast feedback is critical. A newly developed an imaging photon counter provides a wide field of view (18 mm active area) imaging system that is able to detect individual photons within resolution of 10 ps in time and 40 m FWHM in position at a 16 MHz image resolution.
User’s Guide for the Six Month Old Infant Dummy (CRABI)J2854_201711 (Current)11/8/2017
The CRABI dummy was developed to evaluate small child restraint systems in automotive crash environments, in all directions of impact, with or without air bag interaction Basic anthropometry for this test device was taken from the University of Michigan Transportation Research Institute Report 85-23. Weight distribution and scaling methods for the infant were approved by the Society of Automotive (SAE) Infant Dummy Task Group. The dummy weighs 17.2 pounds and has a 26.4 inches standing or 17.3 inches sitting height. The Hybrid Ill-like neck and lumbar spine are laterally notched to reduce lateral stiffness The shoulders have flesh support for durability and human-like performance in areas where seatbelt webbing may be placed. In addition, rubber elements are used in each joint to improve biofidelity and to give the CRABI infant-like range of motion. The CRABI Six-Month-Old design meets all the SAE Infant Dummy Task Group anthropometry, biomechanical and instrumentation requirements. The instrumentation design incorporates three 6-channel load cells to provide load measurements at the C1, C7 and L5 vertebrae locations. Accelerometers are used to measure head, chest and pelvic acceleration and head angular acceleration. All instrumentation is easily accessed
Dummy Testing and Equipment Committee
Simulation of Advanced Regenerative Braking Strategies in a Series Plug-in Hybrid Electric Vehicle2017-01-246610/8/2017
Regenerative braking is an important factor in improving hybrid electric vehicle efficiency. This paper proposes a new regenerative braking strategy that activates preemptively during a distracted driving scenario, before service brakes are utilized. The strategy uses onboard advanced driver assistance systems, such as forward facing radar, to detect when an object is approaching fast enough to enable regenerative braking in response. The proposed strategy is simulated on a full-vehicle model of a series plug-in hybrid electric vehicle. A driver model is developed to mimic the behavior of a distracted driver through delayed response time to the changing speed of a lead vehicle. Multiple trials are simulated using different combinations of existing regenerative braking strategies along with the proposed strategy. Results show that a preventative regenerative braking control strategy can recuperate significant amounts of energy while also improving vehicle safety. Coupling the proposed strategy with an existing brake pedal regeneration strategy returns energy recuperation results that are higher than a system consisting of brake pedal regeneration coupled with coast regeneration.
Arnold, Graham
Impact of In-Vehicle Touchscreen Size on Visual Demand and Usability2017-01-19849/23/2017
Given the wide adoption of touchscreens in vehicles, an interesting debate is taking place regarding the good screen size, length-width ratio and whether the usability of in-vehicle information system (IVIS) would be decreased by a larger screen, especially. Moreover, the lack of scientific evidence about the concrete impact of touch screen size on usability raises questions to practitioners. In this paper, we investigated the impact of in-vehicle touch screen size on users’ visual behavior and usability as measured using eye tracker and questionnaire. Two experiments were conducted on 30 participants. In the first experiment, participants were asked to seek same information on four different in-vehicle screens based on simulated driving environment, while eye movement was recorded for analyzing efficiency of visual behavior. In the second experiment, as secondary driving tasks tested in real driving environment, touch operations of same functions were implemented, including calling, playing music and adjusting air conditioner temperature. Touch areas of these tasks were similar in different vehicles to ensure the comparability. Furthermore, eye movements were recorded and system usability scales were completed for evaluating the usability of in-vehicle touch screen. As for analyzing, usability is evaluated by effectiveness, efficiency, perceived usability and driving compatibility. Four vehicles, namely Tesla model S, Volvo XC90, Cadillac CT6 and Mazda Alexa, were selected for these two experiment, considering that they had different size and length-width ratio screens. In consideration of visual demand and usability, it seems that large vertical touchscreens ≥inch, length-width ratio<1) are the best choice for IVIS.
Ma, Jun, Li, Junyi, Gong, Zaiyan, Yu, Jihong
Integration Drives the Future of Portable Healthcare DevicesTBMG-270086/1/2017
Electric Field Activated Shape Memory Polymer CompositeTBMG-266344/1/2017
NASA’s Langley Research Center has developed a novel shape memory polymer (SMP) made from composite materials for use in morphing structures. In response to an external stimulus such as a temperature change or an electric field, the thermosetting material changes shape, but then returns to its original form once conditions return to normal. Through a precise combination of monomers, conductive fillers, and elastic layers, the NASA polymer matrix can be triggered by two effects — Joule heating and dielectric loss — to increase the response. The new material remedies the limitations of other SMPs currently on the market; namely, the slow stimulant response times, the strength inconsistencies, and the use of toxic epoxies that may complicate manufacturing. NASA has developed prototypes and now seeks a partner to license the technology for commercial applications.
A Modular Apparatus and Method for Attaching Multiple DevicesTBMG-266464/1/2017
Scientists at NASA's Glenn Research Center have received several patents for fabrication methods that speed the production of silicon carbide (SiC) sensors and electronics, reduce fabrication costs, and enable advanced semiconductor functionality at temperatures greater than 600 °C. Glenn has developed a method for fabricating ultra-thin SiC microstructures using a dopant selective reactive ion etching (DSRIE) technique that can create extremely thin diaphragms (approximately 2 microns), increasing sensor sensitivity and resolution. In addition, Glenn has developed a modular protective packaging that allows SiC-based electronic devices to survive and operate reliably at very high temperatures. These innovations improve the real-time monitoring of high-temperature harsh environments, such as jet and rocket engines, allowing faster response times and more accurate readings.
Vehicle Controller Area Network Response Time Analysis and Measurement Issues - to Reduce the Gap between Estimation and Measurement *CSP Meta QA Testing*2017-01-00183/28/2017
Along with the efforts to cope with the increase of functions which require higher communication bandwidth in vehicle networks using CAN-FD and vehicle Ethernet protocols, we have to deal with the problems of both the increased busload and more stringent response time requirement issues based on the current CAN systems. The widely used CAN busload limit guideline in the early design stage of vehicle network development is primarily intended for further frame extensions. However, when we cannot avoid exceeding the current busload design limit, we need to analyze in more detail the maximum frame response times and message delays, and we need good estimation and measurement techniques. There exist two methods for estimating the response time at the design phase, a mathematical worst-case analysis that provides upper bounds, and a probability based distributed response time simulation. While both provide valuable information at design phase, we cannot easily measure message response times using the established bus tracing techniques because those bus traffic traces only contain the reception times of each message. Determining the response time requires knowing also the point in time this message is generated within the control unit, which is usually not possible. In this paper, we present an approach to approximate these intra-ECU message generation times in order to enable reasonable response time measurements. The approach uses a new frame-burst timing analysis that solely uses the standard bus trace information, in particular the reception times of frames. The improved method reduces the gap of estimation and measurement of timing behavior in a CAN network and enables analyzing the network timing efficiently at all phases of vehicle network developments.
Kim, Jeong Chan, Richter, Kai, Koo, Myung Hyun, Hagner, Matthias, Lee, Chung Hi
Activation Timing of a Collision Avoidance System with V2V Communication2017-01-00393/28/2017
A vehicle-to-vehicle communication system (V2V) sends and receives vehicle information by wireless communication and assists safe driving. The present study investigated the activation timings of collision information support, collision caution support, and collision warning support provided by a V2V in an experiment using a driving simulator for four situations of (1) assistance in braking, (2) assistance in accelerating, (3) assistance in making a right turn, and (4) assistance in making a left turn at a blind intersection. The four situations are common scenarios of traffic accidents in Japan. Safety margins for collision information support and collision warning support were the time required for the driver to fully apply the brake pedal, while the safety margin for collision caution support was the time required for the driver to begin applying the brake pedal. The study investigated the effects of adding safety margins to standard activation timings. The standard activation timings referred to activation timings defined by V2V guidelines of the Japanese Ministry of Land, Infrastructure, Transport and Tourism. The effects of new activation timings were investigated in the experiment. Objective (based on the use of the accelerator and braking pedals) and subjective evaluations were made of the activation timings. As result, in the case of collision warning support, the appropriate activation timing of V2V is 2.0 s in all experimental conditions. The timing of 2.0 s means that the safety margin is added twice to the standard activation timing. The collision caution support has appropriate activation timing if the safety margin is added once to the standard activation timing under several experimental conditions. In the case of collision information support, the appropriate activation timing was the addition of one safety margin to the standard activation timing in all experimental conditions.
Hirose, Toshiya, Ohtsuka, Yasufumi, Gokan, Masato
Can You Still Look Up? Remote Rotary Controller vs. Touchscreen2017-01-13863/28/2017
The popularity of new Human-Machine-Interfaces (HMIs) comes with growing concerns for driver distraction. In part, this concern stems from a rising challenge to design systems that can make functions accessible to drivers while maintaining drivers’ ability to cope with the complex driving task. Therefore, engineers need assessment methods which can evaluate how well a user interface achieves the dual-goal of making secondary tasks accessible, while allowing safe driving. Most prior methods have emphasized measuring off-road glances during HMI use. An alternative to this is to consider both on-road and off-road glances, as done in Kircher and Ahlstrom’s AttenD algorithm [1]. In this study, we compared two types of prevalent visual-manual user interfaces based on AttenD. The two HMIs of interest were a touchscreen-based interface (already in production) and a remote-rotary-controller-based interface (a high-fidelity prototype). Five in-vehicle tasks were evaluated, including a continuous-control task, a shortcut task, a menu-navigation task, a list-operation task and a function-switch task. Sixteen participants’ glance behavior was manually coded to apply AttenD. Results suggested that with a higher-positioned display and haptic feedback, the rotary-controller helped drivers maintain attention to the roadway better than the touchscreen-based interface for simple continuous control and shortcut tasks. For the more complex tasks, the results were mixed with interesting insights. Additionally, the AttenD also revealed significant individual differences in attention management strategy. In summary, AttenD-like algorithms not only can compare different HMIs, but also can reveal individual attention allocation strategies.
Zhang, Yu, Angell, Linda, Pala, Silviu, Hara, Tetsuya, Vang, Doua
Accelerator-to-Brake Pedal Transition Movements during On-Road Stopping in an Older Population2017-01-13963/28/2017
Unintended acceleration events due to pedal misapplication have been shown to occur more frequently in older vs. younger drivers. While such occurrences are well documented, the nature of these movement errors is not well-characterized in common pedal error scenarios: namely, on-road, non-emergency stopping or slowing maneuvers. It is commonly assumed that drivers move in a ballistic or “direct hit” trajectory from the accelerator to the brake pedal. However, recent simulator studies show that drivers do not always move directly between pedals, with older drivers displaying more variable foot trajectories than younger drivers. Our study investigated pedal movement trajectories in older drivers ages 67.9 ± 5.2 years (7 males, 8 females) during on-road driving in response to variable traffic light conditions. Three different sedans and a pick-up truck were utilized. Pedal movements were recorded in response to traffic lights that turned yellow at four different vehicle-to-stop bar distances, or were red-on-approach (i.e. the light was red when it entered the driver’s visual field). Pedal movements were grouped into four categories based on foot trajectory (ballistic, above-pedal hovering, pedal tapping, or between-pedal hesitation). At the shortest stopping distance (165 ft), drivers only utilized ballistic movements; at intermediate stopping distances (275 ft and 365 ft), drivers displayed other pedal movement behaviors including hovering and tapping, but continued to utilize a ballistic approach for the majority of the trials (approximately 76%); at long stopping distances (500 ft and red-on-approach) drivers utilized hovering, pedal tapping, and between-pedal hesitation behaviors more frequently (in approximately 48% of trials). Such non-ballistic approaches to pedal transitions could lead to an increased incidence of pedal misapplication. Our findings imply that more long duration braking scenerios may predispose drivers to pedal errors, as more variability is observed when long duration braking is available as an option.
Sharpe, Sarah S., Brinkerhoff, Robyn, Crump, Caroline, Young, Douglas
Bayesian Estimation of Drivers’ Gap Selections and Reaction Times in Left-Turning Crashes from Event Data Recorder Pre-Crash Data2017-01-14113/28/2017
For at least 15 years it has been recognized that pre-crash data captured by event data recorders might help illuminate the actions of drivers prior to crashes. In left-turning crashes where pre-crash data are available from both vehicles it should be possible to estimate features such as the location and speed of the opposing vehicle at the time of turn initiation and the reaction time of the opposing driver. Difficulties arise however from measurement errors in pre-crash data and because the EDR data from the two vehicles are not synchronized so the resulting uncertainties should be accounted for. This paper describes a method for accomplishing this using Markov Chain Monte Carlo computation. First, planar impact methods are used to estimate the speeds at impact of the involved vehicles. Next, the impact speeds and pre-crash EDR data are used to reconstruct the vehicles’ trajectories during approximately 5 seconds preceding the crash. Interpolation of these trajectories is then used to estimate speeds and distances at critical times. The method is illustrated using three cases from the NASS/CDS database.
Davis, Gary A.
Diesel Spray Characterization at Ultra-High Injection Pressure of DENSO 250 MPa Common Rail Fuel Injection System2017-01-08213/28/2017
High fuel injection pressure has been regarded as a key controlling factor for internal combustion engines to achieve good combustion performance with reduced emissions and improved fuel efficiency. For common-rail injection system (CRS) used in advanced diesel engines, fuel injection pressure can often be raised to beyond 200 MPa. Although characteristics of diesel spray has been thoroughly studied, little work has been done at ultra-high injection pressures. In this work, the characteristics of CRS diesel spray under ultra-high injection pressure up to 250 MPa was investigated. The experiments were conducted in an optically accessible high-pressure and high-temperature constant volume chamber. The injection pressure varied from 50 MPa to up to 250 MPa. Both non-evaporating condition and evaporating condition were studied. A single-hole injector was specially designed for this investigation. High-speed Mie-scattering imaging and Schlieren imaging were used to capture the global structure of the liquid and vapor sprays. In addition, high-speed microscopic back-lit imaging was used to obtain detailed information of sprays near the nozzle. Results show that, the increase of injection pressure from 50 MPa to 250 MPa decreases the injection response time and cut time by 58% and 49% respectively. A correlation of injection rate and the velocity of initial spray was observed. The initial spray experiences a quick accelerating to its maximum velocity, then quickly slows down, and higher injection pressure results in shorter accelerating time and higher maximum velocity. In addition, spray liquid penetration increases as injection pressure increases under non-evaporating conditions. However, under evaporating conditions, the increase of injection pressure from 50 MPa to 250 MPa results in about 15% decrease of liquid penetration but increase of vapor penetration.
Xu, Qinglin, Xu, Min, Hung, David, Wu, Shengqi, Dong, Xue, Ochiai, Hiroaki, Zhao, Zhisong, Wang, Caixia, Jin, Kaiyue
Study on Characteristics of Motor Output Power Depending on Current Sensor Response in Eco-Friendly Vehicles2017-01-12223/28/2017
The current sensor for motor control is one of the main components in inverters for eco-friendly vehicles. Recently, as the higher performance of torque control has become required, the current sensor measurement error and accuracy of motor controls have become more significant. Since the response time of the sensor affects the motor output power, the response delay of the sensor causes measurement errors of the current. Accordingly, the voltage vector changes, and a motor output power deviation occurs. In the case of the large response delay of the sensor, as motor speed increases, then difference between motoring and generating output power becomes larger and larger. This results in the deterioration of power performance in high-speed operation. The deviation of the voltage vector magnitude is the main cause of motor output power deviation and imbalance through the simulation. In addition, motor output power deviation and imbalance between motoring and generating power can be reduced by compensating the delay angle of the sensor according to motor speed. In this paper, to overcome the motor output power imbalance due to the response delay of the current sensor, we propose two compensation methods as follows. The first method involves compensating the current reference according to the speed of the motor and the response time of the current sensor. The second method involves compensating the angle of the position sensor according to the speed of the motor and the response time of the current sensor. Simulations and experiments have demonstrated the effectiveness of these methods. By using the proposed methods, the motor output power deviation can be reduced from -5.8% to 0.4% in the case of a current sensor increasing a 5usec delay. As a result, it can be expected to improve driving performance and fuel efficiency.
Rho, Jeongwon, Yim, Jeongbin, Han, Daewoong, Kang, Gubae, Lim, Seongyeop
Items per page:
1 – 50 of 469