Making Transport Safer: V2V-Based Automated Emergency Braking System

An important goal in the field of intelligent transportation systems (ITS) is to provide driving aids aimed at preventing accidents and reducing the number of traffic victims. The commonest traffic accidents in urban areas are due to sudden braking that demands a very fast response on the part of drivers. Attempts to solve this problem have motivated many ITS advances including the detection of the intention of surrounding cars using lasers, radars or cameras. However, this might not be enough to increase safety when there is a danger of collision. Vehicle to vehicle communications are needed to ensure that the other intentions of cars are also available. The article describes the development of a controller to perform an emergency stop via an electro-hydraulic braking system employed on dry asphalt. An original V2V communication scheme based on WiFi cards has been used for broadcasting positioning information to other vehicles. The reliability of the scheme has been theoretically analyzed to estimate its performance when the number of vehicles involved is much higher. This controller has been incorporated into the AUTOPIA program control for automatic cars. The system has been implemented in Citroën C3 Pluriel, and various tests were performed to evaluate its operation

New trends in electrical vehicle powertrains

The electric vehicle and plug-in hybrid electric vehicle play a fundamental role in the forthcoming new paradigms of mobility and energy models. The electrification of the transport sector would lead to advantages in terms of energy efficiency and reduction of greenhouse gas emissions, but would also be a great opportunity for the introduction of renewable sources in the electricity sector. The chapters in this book show a diversity of current and new developments in the electrification of the transport sector seen from the electric vehicle point of view: first, the related technologies with design, control and supervision, second, the powertrain electric motor efficiency and reliability and, third, the deployment issues regarding renewable sources integration and charging facilities. This is precisely the purpose of this book, that is, to contribute to the literature about current research and development activities related to new trends in electric vehicle power trains.Peer ReviewedPostprint (author's final draft

Integration of anti-lock braking system and regenerative braking for hybrid/electric vehicles

Vehicle electrification aims at improving energy efficiency and reducing pollutant emissions which creates an opportunity to use the electric machines (EM) as Regenerative Braking System (RBS) to support the friction brake system. Anti-lock Braking System (ABS) is part of the active safety systems that help drivers to stop safely during panic braking while ensuring the vehicle’s stability and steerability. Nevertheless, the RBS is deactivated at a safe (low) deceleration threshold in favour of ABS. This safety margin results in significantly less energy recuperation than what would be possible if both RBS and ABS were able to operate simultaneously. Vehicle energy efficiency can be improved by integrating RBS and friction brakes to enable more frequent energy recuperation activations, especially during high deceleration demands. The main aim of this doctoral research is to design and implement new wheel slip control with torque blending strategies for various vehicle topologies using four, two and one EM. The integration between the two braking actuators will improve the braking performance and energy efficiency of the vehicle. It also enables ABS by pure EM in certain situations where the regenerative brake torque is sufficient. A novelmethod for integrating the wheel slip control and torque blending is developed using Nonlinear Model Predictive Control (NMPC). The method is well known for the optimal performance and enforcement of critical control and state constraints. A linear MPC strategy is also developed for comparison purpose. A pragmatic brake torque blending algorithm using Daisy-Chain with sliding mode slip control is also developed based on a pre-defined energy recuperation priority. Simulation using high fidelity model using co-simulation in Matlab/Simulink and CarMaker is used to validate the developed strategies. Different test patterns are used to evaluate the controllers’ performance which includes longitudinal and lateral motions of the vehicle. Comparison analysis is done for the proposed strategies for each case. The capability for real-time implementation of the MPC controllers is assessed in simulation testing using dSPACE hardware

Engineering assessment of current and future vehicle technologies: FMVSS no. 105 hydraulic and electric brake systems, FMVSS no. 135 passenger car brake systems; final report

This report provides a technical assessment of Federal Motor Vehicle Safety Standards (FMVSS) 105, Hydraulic and electric brake systems, and FMVSS 135, Passenger car brake systems. The review of these standards is part of a NHTSA’s Regulatory Review Plan to systematically examine all of the FMVSS. The primary thrust of the document is to address two questions: Do the current standards impede emerging technologies in passenger car and light/medium truck braking systems? Do the current standards require modification to adequately regulate emerging technologies? Emerging technologies are reviewed. Estimates of the extent and timing of their influence are made. It is concluded that the standards will not impede emerging technologies in the foreseeable future but could do so in the long term. The view is expressed that the approach of the current standards to ensuring adequate performance under partial-failure conditions may become ineffective as more, and more complex, automatic functions are added to automotive brake systems. A new approach may be required. Seventy-eight references are included in an annotated bibliography.National Highway Traffic Safety Administrationhttp://deepblue.lib.umich.edu/bitstream/2027.42/55414/1/99826.pd

Conception d’un embrayage de dérivation du couple à courants de Foucault pour les transmissions manuelles automatisées sans interruption de couple dans les véhicules à motorisation électrique ou hybride

Les voitures électriques ont peu d’énergie embarquée pour se mouvoir comparativement aux véhicules thermiques. Il est donc important d’optimiser l’efficacité de la chaîne de traction pour maximiser la distance parcourue entre les recharges. Ces voitures utilisent un ratio simple pour coupler le moteur aux roues de la voiture. Le remplacement du ratio simple par une transmission à plusieurs vitesses dans une voiture électrique améliore l’efficacité du système de propulsion. Cependant, l’introduction d’une transmission à plusieurs ratios ne doit pas seulement améliorer l’efficacité énergétique pour recevoir l’acceptabilité du marché. Elle doit aussi offrir un confort de conduite similaire au ratio simple. L’ajout d’un embrayage de déviation du couple à la transmission manuelle permet de réduire ou d’éliminer les interruptions de celui-ci lors du passage des ratios. Cependant, les technologies d’embrayages à friction secs et humides ne sont pas bien adaptées à cette tâche de déviation du couple cependant. D’abord, l’embrayage est ouvert la majeure partie du temps ce qui fait en sorte qu’un embrayage humide aurait de grandes pertes visqueuses. Ensuite, les moteurs électriques tournent rapidement (11 000 révolutions par minute). Cela fait en sorte que l’embrayage dissipe de grandes quantités de chaleur pour ralentir le moteur avant l’engagement du prochain ratio. Un embrayage sec ne contient pas d’huile pour aider à l’extraction de la chaleur et ses bandes de friction s’usent rapidement sous ces conditions. Ce travail de maîtrise propose d’utiliser un embrayage électromagnétique plutôt qu’un embrayage à friction pour dévier le couple moteur. La démarche de conception d’un tel embrayage est présentée. Premièrement, un modèle analytique simple sert à déterminer les dimensions physiques de l’embrayage pour qu’il développe un certain couple électromagnétique. Ce requis provient des spécifications techniques d’une plateforme véhiculaire électrique disponible à l’Université de Sherbrooke (Projet Phoebus). Deuxièmement, des études par éléments finis des champs magnétiques de l’embrayage servent à valider que l’embrayage produit le niveau de couple désiré. L’embrayage est finalement testé dans une transmission manuelle automatisée installée sur un banc de test dynamométrique. Des changements de ratios sans interruption de couple démontrent la viabilité de l’embrayage à courants de Foucault en tant qu’embrayage de déviation du couple

Development of a Hybrid Vehicle Powertrain Test Laboratory

During the last two years, Embry-Riddle Aeronautical University has installed and tested a fully functional eddy-current chassis dynamometer testing facility on campus. An automotive test facility requires a systems engineering approach to install, calibrate and commission a chassis dynamometer. This thesis shows that, the dynamometer test facility was successfully installed, commissioned and documented to safely support the power train development and testing. We can currently test the EcoCAR vehicle and a number of other front-wheel-drive vehicles at our university campus using the eddy current chassis dynamometer

Análisis científico y tecnológico a través de la instrumentación electrónica del desarrollo de sistemas diagnósticos asociados a los frenos de disco en un vehículo particular en los últimos diez años.

Este trabajo presenta una revisión de los sistemas de diagnóstico asociados con los frenos de disco en un vehículo en particular. Este estudio presenta una metodología exploratoria, soportada por bases de datos científicas y tecnológicas, que incluye una revisión de: a) Enfoque numérico y computacional, b) Sensores invasivos y c) Sensores no invasivos. El objetivo es identificar los métodos, estudios y desarrollos de sistemas de diagnóstico que permitan monitorear el sistema de frenado de un vehículo en particular, dado que el Semillero de Investigación en Instrumentación y Telemática (SIIT) requiere desarrollar el sistema de diagnóstico de frenos de disco e implementar este dispositivo en fases posteriores. La principal conclusión de este estudio es considerar el monitoreo y control de la temperatura en las partes fijas y móviles del sistema de frenado, teniendo en cuenta que cada componente tiene un tipo especial de sensor. Se recomienda no utilizar sensores invasivos en partes móviles, para evitar su destrucción también se determina que la mayoría de los desarrollos se basan en análisis computacionales, simulaciones e implementación de bancos de instrumentación.This paper presents a review of the diagnostic systems associated with disc brakes on a particular vehicle. This study presents an exploratory methodology, supported by scientific and technological databases, includes a review of: (a) Numerical and computational approach, (b) Invasive sensors and (c) Non-invasive sensors. The objective is identify the methods, studies and developments of diagnostic systems that allow monitoring the brake system of a particular vehicle, given that the Instrumentation and Telematics Research Seedbed (SIIT) requires developing the disc brake diagnostic system and implement this device in later phases. The main conclusion of this study is consider temperature monitoring and control in the fixed and moving parts of the braking system, consider that each component has a special type of sensor. It is recommended not use invasive sensors in mobile parts, to avoid their destruction it is also determined that most of the developments are based on computational analysis, simulations and implementation of instrumentation banks

Magnetically Actuated Hybrid Brake for Autonomous, Electrified Vehicles

Autonomous driving, the electrification of the powertrain and the reduction of emissions are three major development trends in today’s automotive industry. New mobility solutions such as electrified, autonomous shuttles for transporting people and goods in cities are being conceived and require a change of view in development, not only on the software level but also on chassis components. For braking systems, there are changes in the requirements for these vehicles. Existing test specifications for the performance of wheel brakes for passenger cars are primarily designed for the worst-case scenarios that can be caused by a human driver. Based on a stakeholder analysis as well as a use-case consideration new requirements are generated and new test specifications are developed, which are tailored to autonomous shuttles. Especially the restriction of the Operational Design Domain of the autonomous shuttle results in significantly lower thermal requirements for the wheel brake compared to conventional passenger cars. Nevertheless, high braking torques are still required due to high vehicle masses and the scenario of non-availability of the regenerative brake. Based on the identified requirements and development goals from the analysis, the solution space of braking systems in the state of the art is considered and the suitability of different brake concepts is discussed. Although current hydraulic concepts for passenger cars meet the dynamic and thermal requirements, they have little potential for reducing emissions and tend to corrode due to the increasing duration between actuations when regenerative brakes are in use. As an alternative, the focus of development lies on electromechanical concepts for individual wheel brake modules with electromotive actuation, which in the event of a fault only leads to the failure of one of four wheel brakes. Previous concepts of electromotively actuated brakes show a development conflict in the fact that many gear stages are necessary due to the high transmission ratios, which show a high efficiency variance over temperature due to their lubricants. In the concept space of electromechanical actuators, electromagnets can be found in addition to electric motors. However, only a few concept studies have been published regarding the state of the art and research, although electromagnetic actuation promises some advantages over electromotive actuation. These include less complex actuation, smaller installation space, and less mechanical complexity. Due to the revealed gap in the state of the art, an electro-magnetic concept is selected to be investigated for its suitability as a wheel brake for an autonomous shuttle. For this purpose, either holding magnets or solenoids can be used as actuators, with holding magnets promising significantly higher magnetic forces at small air gaps. For the investigations, a first design of a drum brake actuated by a holding magnet is prototypically realized. The concept comprises a combination of a magnetically actuated solid disc brake with a downstream duplex drum brake. The interconnection of the two brakes promises the utilization of the wheel rotation angle for actuation of the drum brake and a redundant actuator design through the use of two excitation coils in the mag-netic disc brake. To evaluate the suitability of the concept, actuator forces, dynamics, total torques and disc brake torques are measured in operation. The largest deviations from the design considerations occur in the torque curve of the brake over speed, which are investigated in more detail using a hypothesis- and test-based approach. In addition to investigations into the influence of magnetic field weakening effects, such as eddy currents, the coefficient of friction of the friction partners on the holding magnet actuator is also determined and identified as the main cause of the torque drop. A dependence on both the velocity and the axial force is examined. The investigation of the torque hysteresis of the overall braking system shows the difficulty in setting small torques, since the magnet has a high current demand to pass the initial air gap, which then generates medium torques when it hits the disc. A proposal for control by means of a current pre-control is also being tested and evaluated. Through the investigations carried out, the development conflict in the use of a holding-magnetic actuator concept for the actuation of a wheel brake is recorded, and through the hypothesis-based approach the causal effect of the torque drop is identified. The realized magnetic actuator concept fulfills the requirements for dynamics and the wish for low-emission, compact braking concepts, but does not achieve the required braking torques over the entire operating range of an autonomous shuttle. In the outlook a proposed conceptual solution of actuation by means of solenoid actuators is discussed, which promises to solve the described development conflict, but in turn requires a higher transmission ratio due to the lower force potential