Stationary Vehicle Research Articles

226 静止時における自立走行二輪車のモデリングとロバスト姿勢制御(ビークル・コントロール,OS-2:運動と振動のモデリングと制御(1))

Stability of Two-wheeled vehicles depends on their running speed. The running vehicle at high speed is stable but the vehicle in a state of stillness is unstable. In order to stabilize Two-wheeled vehicles in the state of stillness, center-of-gravity movement and handle operation by the rider are indispensable. Then we develop a stationary self-sustaining Two-wheeled vehicle which is a two-wheeled vehicle equipped with a cart system to move a center-of-gravity of the vehicle for stabilizing the system. We derive a state space model of system based on Lagrange method and identified model parameters by control experiments. A robust attitude controller is designed via Loop Shaping Design Procedure (LSDP). Experimental results show an effectiveness of the derived mathematical model and the designed robust attitude controller compared with LQ controller.

A death in a stationary vehicle whilst idling: unusual carbon monoxide poisoning by exhaust gases

In this paper, we describe an autopsy case in which death was due to accidental carbon monoxide poisoning occurring in a stationary vehicle idling in an open space. To investigate the source of the fatal fumes, the death scene situation was reconstructed using the vehicle. Exhaust gases were found to invade the interior through the floor from a defective exhaust system. CO gas was detected while idling and the level in the cabin gradually rose to 1.5% over a 2-h period. Since the 8-year-old motor vehicle seemed to have been defective for some months, it was concluded that stationary idling overnight caused an accumulation of toxic gases in the interior.

A Study on Adapting the Zoom FET Algorithm to Automotive Millimetre Wave Radar

The millimetre wave radar has been developed for automotive application such as ACC (Adaptive Cruise Control) and CWS (Collision Warning System). The radar uses MMIC (Monolithic Microwave Integrated Circuits) devices for transmitting and receiving 76 GHz millimetre wave signals. The radar is FSK (Frequency Shift Keying) monopulse type. The radar transmits 2 frequencies in time-duplex manner, and measures distance and relative speed of targets. The monopulse feature detects the azimuth angle of targets without a scanning mechanism. The Zoom FFT (Fast Fourier Transform) algorithm, which analyses frequency domain precisely, has adapted to the radar for discriminating multiple stationary targets. The Zoom FFT algorithm is evaluated in test truck. The evaluation results show good performance on discriminating two stationary vehicles in host lane and adjacent lane.

Application of Probe-Vehicle Data for Real-Time Traffic-State Estimation and Short-Term Travel-Time Prediction on a Freeway

Traffic information from probe vehicles has great potential for improving the estimation accuracy of traffic situations, especially where no traffic detector is installed. A method for dealing with probe data along with conventional detector data to estimate traffic states is proposed. The probe data were integrated into the observation equation of the Kalman filter, in which state equations are represented by a macroscopic traffic-flow model. Estimated states were updated with information from both stationary detectors and probe vehicles. The method was tested under several traffic conditions by using hypothetical data, giving considerably improved estimation results compared to those estimated without probe data. Finally, the application of the proposed method was extended to the estimation and short-term prediction of travel time. Travel times were obtained indirectly through the conversion of speeds estimated or predicted by the proposed method. Experimental results show that the performance of travel-time estimation or prediction is comparable to that of some existing methods.

Fuel cell system economics: comparing the costs of generating power with stationary and motor vehicle PEM fuel cell systems

This investigation examines the economics of producing electricity from proton-exchange membrane (PEM) fuel cell systems under various conditions, including the possibility of using fuel cell vehicles (FCVs) to produce power when they are parked at office buildings and residences. The analysis shows that the economics of both stationary fuel cell and FCV-based power vary significantly with variations in key input variables such as the price of natural gas, electricity prices, fuel cell and reformer system costs, and fuel cell system durability levels. The “central case” results show that stationary PEM fuel cell systems can supply electricity for offices and homes in California at a net savings when fuel cell system costs reach about $6000 for a 5 kW home system ($1200/kW) and $175,000 for a 250 kW commercial system ($700/kW) and assuming somewhat favorable natural gas costs of $6/GJ at residences and $4/GJ at commercial buildings. Grid-connected FCVs in commercial settings can also potentially supply electricity at competitive rates, in some cases producing significant annual benefits. Particularly attractive is the combination of net metering along with time-of-use electricity rates that allow power to be supplied to the utility grid at the avoided cost of central power plant generation. FCV-based power at individual residences does not appear to be as attractive, at least where FCV power can only be used directly or banked with the utility for net metering and not sold in greater quantity, due to the low load levels at these locations that provide a poor match to automotive fuel cell operation, higher natural gas prices than are available at commercial settings, and other factors.

Unsafe at Any (Wind) Speed?

The goal of this research was to examine the relative safety and stability of stationary motor vehicles exposed to severe winds. The focus was on private passenger vehicles. 1) The behavior of two instrumented storm-chase vehicles that were exposed to severe winds, 2) the behavior of 291 vehicles exposed to a tornado, and 3) the wind speed required to upset a sedan and a minivan exposed to winds in a wind tunnel were studied. A wind as strong as 47 m s−1 (105 mph) has been measured by a storm-chase pickup truck and 44 m s−1 (98 mph) by a storm chase sedan. The vehicles were not adversely affected by the wind. Also studied were 291 vehicles parked outdoors at homes struck by tornadoes, and the behavior of the vehicles was compared to the F-scale damage to the house. At sites with F1 or F2 damage, 72% of the vehicles were not moved by the wind and 96% were not tipped over. At sites with F3 or F4 damage, 50% were not moved by the wind and 82% were not tipped over. Wind tunnel tests on a sedan and minivan showed they were most vulnerable to upset (lifting of one tire from the ground) with wind directions near 45° and 135°, as measured from the front. When modeled with 5° of suspension tilt to the side, the sedan was found to be upset at wind speeds of 51–67 m s−1 (115–150 mph), and the minivan was upset at wind speeds of 58–80 m s−1 (130–180 mph). Although an underground shelter or sturdy building offer the best protection from severe winds, it is found that a vehicle may be a relatively stable place and may be safer than a mobile home or the outdoors. These findings may warrant changes to public recommendations made during tornado warnings and other severe storm situations.

An analysis of 'looked but failed to see' accidents involving parked police vehicles

Drivers who collide with a vehicle that is parked on the hard shoulder of a motorway or dual-carriageway sometimes claim not to have seen it before the collision. Previous research into vehicle conspicuity has taken such ‘looked but failed to see’ claims at face value, and concentrated on attempting to remedy the problem by making vehicles more conspicuous in sensory terms. However, the present study describes investigations into accidents of this kind which have involved stationary police cars, vehicles which are objectively highly conspicuous. Two laboratory studies showed that experienced drivers viewing a film of dual-carriageway driving were slower to respond to a parked police car as a ‘hazard’ if it was parked directly in the direction of travel than if it was parked at an angle; this effect was more pronounced when the driver's attention was distracted with a secondary reasoning task. Taken together with the accident reports, these results suggest that ‘looked but failed to see’ accidents may arise not because the parked vehicle is difficult to see, but for more cognitive reasons, such as vigilance failure, or possession by the driver of a ‘false hypothesis’ about the road conditions ahead. An emergency vehicle parked in the direction of travel, with only its blue lights flashing, may encourage drivers to believe that the vehicle is moving rather than stationary. Parking at an angle in the road, and avoiding the use of blue lights alone while parked, are two steps that drivers of parked emergency vehicles should consider taking in order to alert approaching drivers to the fact that a stationary vehicle is ahead.

Effect of Warning Timing on Collision Avoidance Behavior in a Stationary Lead Vehicle Scenario

Warning timing and how drivers with and without forward collision warning (FCW) systems react when distracted at the moment a stationary vehicle is revealed directly ahead were investigated. The study was conducted using the Iowa Driving Simulator (IDS). The IDS was equipped with an FCW system that provided auditory warnings based on two warning criteria. A total of 30 subjects were split across three conditions—a baseline of 10 subjects (no warning display), and two warning conditions (early and late) with 10 subjects each. The two warning conditions differed by the duration of an a priori driver reaction component (1.5 and 1.0 s) in the warning algorithm. Drivers’ collision avoidance performance in the two warning conditions was compared with that in the baseline condition. Results indicated that the early warning condition showed significantly shorter accelerator release reaction times, fewer crashes, and less severe crashes than both the baseline condition and the late warning condition. The results indicate that the timing of a warning is important in the design of collision warning systems.

A New Control Strategy to Reduce Steering Torque for Vehicles Equipped with Electric Power Steering. Steering Angular Velocity Controller Using the Observer for Specified Frequency.

This paper proposes a new Electric Power Steering (EPS) control strategy that enables remarkable progress on steering maneuverability for stationary vehicles. Using a conventional controller, undesirable steering vibration prevented us from reducing steering torque. To eliminate this vibration, we developed a new control strategy based on steering angular velocity control for specified frequency using a newly developed steering shaft angular-velocity observer. We experimented with this proposed control algorithm using a test vehicle and confirmed that it enables reduced steering torque without any perceived vibration for drivers from slow steering to rapid steering. Concerning the assist-map, the proposed control strategy enabled more than three times higher gradient compared with that of the conventional one. This proposed control strategy requires no supplemental sensors.

R-134a emissions from vehicles.

We report the first study of R-134a (also known as HFC-134a and CF3CFH2) refrigerant leakage from air conditioning (AC) systems of modern vehicles. Twenty-eight light duty vehicles from five manufacturers (Ford, Toyota, Daimler Chrysler, General Motors, and Honda) were tested according to the USEPA (Federal) extended diurnal test procedure using the Sealed Housing for Evaporative Determination (SHED) apparatus. All tests were conducted using stationary vehicles with the motor and air conditioning system turned off. R-134a was measured using gas chromatography (GC) with a flame ionization detector (FID). All vehicles exhibited measurable R-134a leakage over the 2-day diurnal test. Leak rates of R-134a ranged from 0.01 to 0.36 g/day with an average of 0.07+/-0.07 g/day. When combined with leakage associated with vehicle operation, servicing, and disposal we estimate that the lifetime average R-134a emission rate from an AC equipped vehicle is 0.41+/-0.27 g/day (the majority of emissions are associated with vehicle servicing and disposal). Assuming that the average vehicle travels 10 000 miles per year we estimate that the global warming impact of R-134a leakage from an AC equipped vehicle is approximately 4-5% of that of the CO2 emitted by the vehicle. The results are discussed with respect to the contribution of vehicle emissions to global climate change.

Development of lithium batteries for energy storage and EV applications

The results of the Japanese national project of R&D on large-size lithium rechargeable batteries by Lithium Battery Energy Storage Technology Research Association (LIBES), as of fiscal year (FY) 2000 are reviewed. Based on the results of 10 Wh-class cell development in Phase I, the program of Phase II aims at further improvement of the performance of large-size cells and battery modules, and the formulation of roadmaps toward worldwide dissemination of large-size lithium secondary batteries. In addition to the above R&D programs, a new target was presented particularly for the near-term practical application of several kWh-class battery modules in FY 1998. For the large-size battery modules, two types of 2 and 3 kWh-class battery modules have been developed for stationary device and electric vehicle applications, respectively. The battery modules for both types have achieved most of the targets other than cycle life. Currently, further improvements in the cycle life of the cells themselves are being pursued. For this purpose, the materials for cathodes and anodes, the shapes and structures for batteries and the methods for cell connection are being re-investigated. The development of middle-size battery systems for mini-size electric vehicles (EVs), as well as for demand-side stationary device applications is under way. These battery systems have been fabricated and their fundamental performance confirmed. They are now being subjected to field tests.

Young and Old Subject Distance Between Vehicles Estimation Using Linear Distance and “Car Lengths”

Drivers perform distance estimations regarding their vehicle and objects around them (including other vehicles) continuously. Such estimates may employ linear distance or “car lengths”. The reliability of such assessments is often uncertain. The purpose of this investigation was to evaluate a subject's ability to judge distances between stationary vehicles, ranging from very close (15 ft) to 250 ft, using linear length (ft) and “car lengths” and to compare the relative accuracy of these two methods. Age influences were also investigated, grouping subjects into “young” (19-28 yrs) and “old” (64-76 yrs). This study found that the ability to estimate distance between two vehicles in the range 15 to 250 ft is limited, with subjects routinely underestimating the distance. The age influence became statistically significant at distances over 100 ft, with older subjects underestimating the distance even more than younger subjects. Finally, it was found that the length unit “car length” was even more likely to provide inaccurate distance estimations relative to linear length.

Development of Display System for Collision Dangerous Assessment Based on Drivers' Feeling.

In such as collision warning systems and automatic braking systems, it may be difficult for deciding a suitable timing affecting their effectiveness. Thus, toward designing these systems with human factor considerations, a real-world experimental study was conducted. From the data we decided the most suitable visual information (e.g., distance, headway time, and so on) as the index for assessing the collision danger associated with a lead vehicle or a stationary vehicle. The result showed that the index had the dependency of driving situation such as approaching a lead vehicle and avoiding the collision for a stationary vehicle. Using the obtained indices, a display system of collision dangerous assessment was developed and showed the effectiveness experimentally.

Bus Wheel Injuries And A Remedial Method For Prevention Of These Accidents

The Accident Statistics For Injuries Caused By Pedestrians Or Cyclists Being Injured, Or Killed, By U.S. Transit Buses Have Typically Been Categorized Simply As Either Fatalities Or Serious Injuries. Although Anecdotal Information From Police Accident Investigators And Forensic Engineers Have Indicated That Certain Types Of Accidents With Transit Buses Are More Prevalent Than Other Types, Definitive Data Has Been Lacking. Recent Risk Management Efforts At Various Transit Authorities2 Have Revealed A Prevalent Type Of Accident From Transit Vehicles Interacting With Either Cyclists Or Pedestrians. The Predominant Accident Type Seems To Be Pedestrians Or Cyclists Being Pulled Into The Bus-Wheel, As Opposed To Individuals Being Struck By The Vehicle Body3. Further Questioning Of Transit Personnel Indicates That, In Most Cases, The Accidents Occur From The Rotating Bus Transit Wheel On The Bus As It Passes The Individual As Opposed To The Cyclist Or Pedestrian Running Into The Stationary Transit Vehicle Or Tire. Surprisingly, The Type Of Accident Where The Bus Strikes The Cyclist Or Pedestrian In An Area Other Than On The Rotating Wheel Is Almost Negligible. The Analysis In This Paper Is Focusing On Transit Authority Buses Since Risk Assessment Managers Have Identified High Incidents Of Injury At The Site Of The Rotating Wheel For These Vehicles.

Bus Wheel Injuries And A Remedial Method For Prevention Of These Accidents

The Accident Statistics For Injuries Caused By Pedestrians Or Cyclists Being Injured, Or Killed, By U.S. Transit Buses Have Typically Been Categorized Simply As Either Fatalities Or Serious Injuries. Although Anecdotal Information From Police Accident Investigators And Forensic Engineers Have Indicated That Certain Types Of Accidents With Transit Buses Are More Prevalent Than Other Types, Definitive Data Has Been Lacking. Recent Risk Management Efforts At Various Transit Authorities2 Have Revealed A Prevalent Type Of Accident From Transit Vehicles Interacting With Either Cyclists Or Pedestrians. The Predominant Accident Type Seems To Be Pedestrians Or Cyclists Being Pulled Into The Bus-Wheel, As Opposed To Individuals Being Struck By The Vehicle Body3. Further Questioning Of Transit Personnel Indicates That, In Most Cases, The Accidents Occur From The Rotating Bus Transit Wheel On The Bus As It Passes The Individual As Opposed To The Cyclist Or Pedestrian Running Into The Stationary Transit Vehicle Or Tire. Surprisingly, The Type Of Accident Where The Bus Strikes The Cyclist Or Pedestrian In An Area Other Than On The Rotating Wheel Is Almost Negligible. The Analysis In This Paper Is Focusing On Transit Authority Buses Since Risk Assessment Managers Have Identified High Incidents Of Injury At The Site Of The Rotating Wheel For These Vehicles.

The relationship between clinical and kinematic responses from human subject testing in rear-end automobile collisions

Recent experiments have produced a linked data set of clinical and kinematic responses for human subjects exposed to controlled low-speed rear-end collisions. The purpose of this paper was to examine this paired data set and determine whether the presence or absence of clinical symptoms could be predicted from the peak linear and angular kinematic response of the head and neck. The data were generated using 42 male and female human subjects seated normally in the front passenger seat of a stationary vehicle struck from behind to produce vehicle speed changes of 4 and 8 km/h. Pre- and post-test clinical examinations documented the presence, severity and duration of whiplash-associated disorders (WAD). Logistic regression and backward elimination of independent variables were used to develop the prediction model. The analysis yielded a 16 parameter model that was significantly related (odds ratio=21.2; P=0.0069) to the presence or absence of transient whiplash symptoms. The model correctly predicted symptom presence in 13 of 23 tests (sensitivity 57%) and symptom absence in 49 of 52 tests (specificity 94%) in a population of 75 with a symptom prevalence of 31%. The model’s positive predictive value was 81% and its negative predictive value was 83%. Despite statistical significance, the model did not discriminate between the presence and absence of symptoms in all tests, and indicated that factors other than the selected peak kinematic responses influenced symptom production.

Navigation Aids: Effects on Crew Workload and Performance

In advanced technological applications, there is a constant need to ensure that the design of the human–machine interface does not add to operator workload. This is particularly true in applications that involve safety-critical and life-threatening situations, such as those encountered in armored vehicles during combat. In this study, we examined the concept of providing the drivers of these vehicles with a new form of electronic navigation aid, which was predicted to reduce workload levels. Experiments indicated that using these digital maps significantly reduced overall crew workload, primarily due to significantly decreased workload of the driver working with the digital map. Furthermore, the new maps improved the performance of keeping to the determined route and the performance of the commander's secondary task of reporting the number of stationary vehicles. This reduced workload plus increased performance was hypothesized to be due to display output compatibility of the digital map considered in the context of the multiple resource model, as developed by Wickens (1992). It was concluded that design options for navigation information could be assessed in conjunction with multiple resource theory, which provides an appropriate framework for consideration of navigation aids in this environment.

Detecting obstructions and tracking moving objects by image processing technique

In this paper, a method is described for updating the background image corresponding to the environment changing the illumination conditions significantly and for detecting obstructions and tracking of moving vehicles on the road. In the proposed method, the varying region in the monitoring image is derived from the background difference and time difference and is classified into (a) moving objects, (b) stationary objects, and (c) the change due to illumination variation. Based on this classification, region (c) and the region without any change are used for background updating. Also, by forming the a cumulative image in which the binary images composed of regions (a) and (b) are stored for a specified length of time, the detection of the stationary objects is performed and the traffic conditions are determined. For tracking of moving objects, first the DCT is used so that the images consisting only of the moving object and excluding shadow are extracted. Next, these images are used as the template and are tracked by matching. The present method was applied to three types of video images. It was found that all of the 10 stationary vehicles contained in the image were detected. Also, a high accuracy of 93% was accomplished for the tracking of moving objects in the case of daytime images. © 1999 Scripta Technica, Electron Comm Jpn Pt 3, 82(11): 28–37, 1999

Detecting Targets from a Moving Vehicle with a Head-Mounted Display and Sound Localization

Eight participants detected and identified pop-up targets on an outdoor range from a stationary and a moving vehicle using a head-mounted display (HMD), with and without sound localization, and direct viewing as a control. A head-slaved camera mounted on top of the vehicle provided the image to the HMD. The computer controlled audio cueing appeared to originate from the location of the target. The results are that although targets were detected sooner with direct viewing from the stationary vehicle without cueing, sound localization improved target detection in all other test modes. More targets were detected and identified with direct vision than with the HMD, and from the stationary position than the moving vehicle. Workload test battery ratings show a significant increase in perceived workload with the HMD as compared to the direct vision. A test of situational awareness shows significant decreases in perceived stability and familiarity and an increased need to concentrate when using the HMD in the moving vehicle. Further, most of the participants reported a general discomfort associated with motion sickness while in the moving vehicle with the HMD. Finally, the participants rated direct viewing as more useful than the HMD, and the sound localization as being of more use with the HMD than with direct viewing.

Influence of street obstructions on flow processes within urban canyons

Abstract This paper is concerned with modelling of the motion of air within the urban environment and is directed towards a deeper understanding and controlling of pollutant dispersion in individual street canyons. Some possible methodologies by which the roughness associated with obstacles, such as small buildings, kiosks, trees and stationary vehicles within the canyon may be described for incorporation into an overall canyon model, are discussed. This is illustrated by results from a simple wind tunnel experiment utilising an idealised two-dimensional street canyon in which the internal roughness is represented by an array of vertical cylinders. These reveal the presence of complex flow patterns within the roughness layer. Integrated and averaged mean velocity and turbulence intensity parameters are presented to indicate the extent of the effect of the presence of the internal roughness upon the canyon flow regime.