Search Results

As wireless technologies evolve, in-vehicle information services are becoming more and more essential to vehicle users. In contrast with information services in the home, in-vehicle information services emphasize the use of information to make driving more comfortable, rather than simply displaying information during driving. In particular, traffic information is, unlike other kinds of information, effective in getting to a destination and therefore, must be real-time to be useful. In Japan, car navigation systems have a large market penetration; dynamic route guidance systems (DRGS) operating in concert with navigation systems have been popular since 1995. This paper discusses mobile information services including DRGS. The focus is on the Japanese market where navigation technologies are the most advanced.

Display devices are required to have some fundamental functions which are brightness & gradation, colorfullness, resolution & sharpness, response time, and suitable size of the picture. Since the CRT (Cathode Ray Tube) is superior to the other display devices in these requirements, it can offer much information efficiently and effectively. Their visibility should not be evaluated only on the basis of some standards for office automation systems. From the point of view of human factors, visibility investigations of the CRTs for automobiles are examined. In this paper the relationship between the chromaticity difference and the luminance contrast for drivers to read the picture easily, and the luminance of the background in the CRTs for drivers not to be dazzled in the nighttime driving are clarified.

This paper proposes a novel method of verifying comprehensive driver model used for the evaluation of driving safety systems, which is achieved by coupling the traffic simulation and the driving simulator (DS). The method consists of three-step procedure. In the first step, an actual driver operates a DS vehicle in the traffic flow controlled by the traffic simulation. Then in the next step, the actual driver is replaced by a driver model and the surrounding vehicle maneuvers are replayed using the recorded data from the first step. Then, the maneuver by the driver model is compared directly with the actual driver's maneuver along the simulation time steps.

Grip feeling is an important facet in vehicle dynamics evaluation from a driver satisfaction and enjoyment standpoint. To improve grip feeling, we analyzed the subjective comments from test driver's about grip feeling and an evaluated human sensitivity to lateral motion. As a result, we found that drivers evaluate transient grip feeling according to the magnitude of lateral jerk. Next, we analyzed what vehicle parameters affect lateral jerk by using theoretical equations. As a result, we found that cornering power is an important parameter, especially the cornering power of rear tires as they can be create larger lateral jerk than can front tires.

Wireless Power Transfer (WPT) promises automated and highly efficient charging of electric and plug-in-hybrid vehicles. As commercial development proceeds forward, the technical challenges of efficiency, interoperability, interference and safety are a primary focus for this industry. The SAE Vehicle Wireless Power and Alignment Taskforce published the Recommended Practice J2954 to help harmonize the first phase of high-power WPT technology development. SAE J2954 uses a performance-based approach to standardizing WPT by specifying ground and vehicle assembly coils to be used in a test stand (per Z-class) to validate performance, interoperability and safety. The main goal of this SAE J2954 bench testing campaign was to prove interoperability between WPT systems utilizing different coil magnetic topologies. This type of testing had not been done before on such a scale with real automaker and supplier systems.

In today's motorized society, various automotive technologies continue to evolve every day. Amid this trend, a new concept with respect to automatic transaxle gear-shifting has been developed. In order to materialize a new concept for shifting operation with a universal design in mind, a system has been developed: a shift-by-wire system developed specifically for hybrid vehicles. The greatest advantage of this new system is the lack of constraints associated with the conventional mechanical linkage to the transaxle. This allows freedom of design for the gear selection module. A revolutionary improvement in the ease of shifting has been realized by taking full advantage of this design freedom. In addition, this system contributes to an innovative design. For improved ease of operation, the operation force of the shift lever of this system has been dramatically reduced. For parking, the driver can engage the parking mechanism of the transaxle at the touch of a switch.

New engine controls have been developed for the turbocharged Lexus NX200t to improve driving power by reducing engine torque output lag. Drive power management functions have been centralized in an integrated drive power control system. The newly developed controls minimize the potential reduction in drivability associated with the adoption of a turbocharged engine while improving fuel efficiency. General driveability issues commonly associated with a turbocharged engine include sudden increases in drive power due to the response lag of the turbocharger, and higher shifting frequencies if this response lag triggers a disturbed accelerator operation pattern by the driver. The developed technologies detect and control sudden increases in drive power to create the optimum drive power map, and reduce unnecessary shifts even if the driver's accelerator operation is disturbed.

This paper describes the newest CRT display system named “Toyota Electro Multivision”, released in the '88 model Toyota Crown. This system has grown to be a total information system, having multiple new functions, including control, operation and displays for the “hands free” phone. This new system uses a compact disc as its memory media. Here we introduce our design concept for the CRT display system, and outline the system and its key technologies.

This paper proposes a theory to analyze the collision avoidance capability of automated driving technologies. The theory gives answers to a fundamental question whether automated vehicles fall into extreme conditions at all rather than another question how a vehicle reacts under extreme conditions (is it as safe as driver?). The theory clarifies the following matters: There are two types of hazards to cause collisions, cognitive hazards and behavioral hazards. Cognitive hazards are handled by controlling the upper limit speed of the automated vehicle including when stopped. There are two methods for handling behavioral hazards, preparation and response. The response known well is the coping method activated when the hazard is detected in the dynamic (operational) level. The preparation is the coping method operating at all time in the semantic (tactical) level.

The need for small personal mobility vehicles is growing as urbanization, the aging of society, traffic congestion, and parking become major issues, particularly in inner-city areas. The aging of society also means that more short trips within communities will be made. The i-REAL personal mobility vehicle is a next-generation single-passenger electric vehicle that enables the driver to move around town using a smaller amount of energy. This compact EV has three wheels: two front wheels driven by in-wheel motors and one rear wheel. According to the driver's needs, the i-REAL switches driving modes by changing its wheelbase. It can go slowly, allowing the driver to meet the eyes of passers-by when driving in parks, on sidewalks, or inside shopping malls. When on the road, it can lower its height and drive quickly like a bicycle or motorcycle. The body of the i-REAL leans automatically based on the speed and the turn angle to maintain the balance of the vehicle for any driver.

The demonstration benefit from fuel-borne fuel-economy additives to a precision of 1%, or better, traditionally requires very careful experimental design and considerable resource intensity. In practice, the process usually requires the use of well-defined drive cycles (e.g. emission certification cycles HFET, NEDC) in conjunction with environmentally-controlled chassis dynamometer facilities. Against this background, a method has been developed to achieve high-precision fuel economy comparison of gasoline fuels with reduced resource intensity and under arbitrary real-world driving conditions. The method relies upon the inference of instantaneous fuel consumption via the collection of OBD data and the simultaneous estimation of instantaneous engine output from vehicle dynamical behaviour.

In 2007, researchers at the Massachusetts Institute of Technology successfully completed a Wireless Power Transfer (WPT) experiment. Ever since, interest in WPT has been growing. At Toyota, we have been developing the underlying technology of a WPT system. Simultaneously we have been working with regulatory committees to create a standard for WPT. In particular, there are concerns that WPT’s radiated emissions could cause harm to humans and the neighboring electronic equipment. There are many challenges that need to be overcome, but a key concern is understanding WPT’s electromagnetic compatibility (EMI: Electro-Magnetic Interference and EMF: Electro-Magnetic Field). In this paper, we show the technical issues, the evaluation method, and the development status of EMI and EMF on PHVs/EVs when using WPT. For Electromagnetic interference (EMI) performance, we investigated both an open area test site and an electromagnetic anechoic chamber as evaluation environments.

The purpose of this study is to propose braking characteristics that are easy for drivers to handle in a system in which braking and driving operations are performed by hand. Genetic algorithm optimization of braking characteristics showed that the best deceleration tracking was achieved by an FG diagram with a logarithmic function shape. In contrast, the slope of the optimal FG diagram tended to decrease as the driver's proportional gain increased.

The human body undergoes a variety of changes as it ages through adulthood. These include both morphological (structural) changes (e.g., increased thoracic kyphosis) and material changes (e.g., osteoporosis). The purpose of this study is to evaluate structural changes that occur in the aging bony thorax and to assess the importance of these changes relative to the well-established material changes. The study involved two primary components. First, full-thorax computed tomography (CT) scans of 161 patients, age 18 to 89 years, were analyzed to quantify the angle of the ribs in the sagittal plane. A significant association between the angle of the ribs and age was identified, with the ribs becoming more perpendicular to the spine as age increased (0.08 degrees/year, p=0.012). Next, a finite element model of the thorax was used to evaluate the importance of this rib angle change relative to other factors associated with aging.

This study aims at the development of a projection pattern that is capable of shortening the time required by a driver to perceive a pedestrian at night when a vehicle’s high beams are utilized. Our approach is based on the spatio-temporal frequency characteristics of human vision. Visual contrast sensitivity is dependent on spatiotemporal frequency, and maximum contrast sensitivity frequency varies depending on environmental luminance. Conventionally, there are several applications that utilize the spatio-temporal frequency characteristics of human vision. For example, the National Television System Committee (NTSC) television format takes into consideration low-sensitivity visual characteristics. In contrast, our approach utilizes high-sensitivity visual characteristics based on the assumption that the higher contrast sensitivity of spatio-temporal frequencies will correlate more effectively with shorter perception times.

We investigated a lighting method that supports pedestrian perception by vehicle drivers. This lighting method makes active use of visual characteristics such as the spatio-temporal frequency of contrast sensitivity. Using reasonable parameter values derived from preliminary experiments using a Campbell-Robson chart, we determined a suitable lighting pattern that improves the driver's pedestrian perception. In order to assess the influence of visual characteristics on a reaction-time-dependent task, such as pedestrian perception in nighttime, tests were performed in the target environment, the results of which validated the proposed method.

The driving simulator (DS) developed by Toyota Motor Corporation simulates acceleration using translational (XY direction) and tilting motions. However, the driver of the DS may perceive a feeling of rotation generated by the tilting motion, which is not generated in an actual vehicle. If the driver perceives rotation, a vestibulo-ocular reflex (VOR) is generated that results in an unnecessary correction in the driver's gaze. This generates a conflict between the vestibular and visual sensations of the driver and causes motion sickness. Although such motion sickness can be alleviated by reducing the tilting motion of the DS, this has the effect of increasing the amount of XY motion, which has a limited range. Therefore, it is desirable to limit the reduction in the tilting motion of the DS to the specific timing and amount required to alleviate motion sickness. However, the timing and extent of the VOR has yet to be accurately identified.

This article proposes a rubber suspension bushing model considering amplitude dependence as a useful tool at the initial design phase. The purpose of this study is not to express physical phenomena accurately and in detail and to explore the truth academically, but to provide a useful design method for initial design phase. Experiments were carried out to verify several dynamic characteristics of rubber bushings under vibration up to a frequency of 100 Hz, which is an important frequency range when designing ride comfort performance. When dynamic characteristic theory and the geometrical properties of the force-displacement characteristic curve were considered using these dynamic characteristics as assumptions, an equation was derived that is capable of calculating the dynamic stiffness under an arbitrary amplitude by identifying only two general design parameters (dynamic stiffness and loss factor) under a reference amplitude.

Ongoing research on active stabilizers involves not only control of the roll angle of the vehicle based on steering input but also improving ride comfort by reducing roll vibration caused by the antiphase road surface input. In that context, roll skyhook control, which applies skyhook theory to provide feedback on the vehicle roll and drive the actuators, has already been presented. Although vibration in all frequency bands can be reduced if there is no control delay, time lags or phase delays in control elements such as the communication, computation, low-pass filter, or actuators can amplify vibration. Consequently, a sufficient effect of controlling cannot be obtained. This paper will address wheelbase filtering, which produces a frequency that minimizes roll oscillation, and is used to suppress the influence of the undesirable vibration.

A dynamics model considering series rigidity was constructed to examine suspension friction, which has a major effect on ride comfort on paved roads. The friction characteristics of the bushings, ball joints, and shock absorbers are expressed with series elastic elements such as arm rigidity and the spring constant of the oil seals. It was confirmed that the calculated values for the overall spring constant and damping coefficient of the suspension virtually matched values measured in a 4-post shaker test. In addition, the results of analysis using this dynamics model confirmed that the degree of friction affects both the damping coefficient and the spring constant of the suspension, especially when the series rigidity is high. Also highly rigid friction has an adverse effect on sprung motion in frequency ranges above 15 Hz. After suspension enhancements were adopted based on these findings, 4-post shaker tests confirmed that sprung motion above 2 Hz improved..