Traffic jam driving with NMV avoidance

n recent years, the development of advanced driver assistance systems (ADAS) – mainly based on lidar and cameras – has considerably improved the safety of driving in urban environments. These systems provide warning signals for the driver in the case that any unexpected traffic circumstance is detected. The next step is to develop systems capable not only of warning the driver but also of taking over control of the car to avoid a potential collision. In the present communication, a system capable of autonomously avoiding collisions in traffic jam situations is presented. First, a perception system was developed for urban situations—in which not only vehicles have to be considered, but also pedestrians and other non-motor-vehicles (NMV). It comprises a differential global positioning system (DGPS) and wireless communication for vehicle detection, and an ultrasound sensor for NMV detection. Then, the vehicle's actuators – brake and throttle pedals – were modified to permit autonomous control. Finally, a fuzzy logic controller was implemented capable of analyzing the information provided by the perception system and of sending control commands to the vehicle's actuators so as to avoid accidents. The feasibility of the integrated system was tested by mounting it in a commercial vehicle, with the results being encouraging

Sistema de control de tráfico para la coexistencia entre vehículos autónomos y manuales mediante comunicaciones inalámbricas

Premio Extraordinario de Doctorado 2012Los avances en el campo de los sistemas inteligentes de transporte (ITS, del inglés Intelligent Transportation Systems) en los últimos años han propiciado la aparición de sistemas que ayudan de manera significativa a los conductores facilitando su labor, relegándoles de tareas tediosas. No es demasiado utópico pensar en un futuro en vehículos completamente automatizados circulando por las carreteras. Sin embargo, se precisa de un sistema de transición desde los vehículos que actualmente circulan por las carreteras hasta los vehículos completamente automatizados y, por ende, la coexistencia entre ellos. En el presente trabajo de tesis doctoral se presenta el diseño, desarrollo e implementación de un sistema global para el control del tráfico con vehículos guiados por conductores humanos o automáticos basado en comunicaciones inalámbricas con un doble objetivo: en primer lugar, disminuir de manera significativa la congestión actual del tráfico, fundamentalmente en entornos urbanos, y en segundo lugar, presentar un sistema seguro que permita pensar en una reducción del número de accidentes en las carreteras o, al menos, mitigar las consecuencias. Para lograr los objetivos propuestos se utilizarán diversas fuentes de información ya sean ubicadas en los vehículos -sistemas de navegación global por satélite (GNSS, del inglés Global Navigation Satellite System), sistemas inerciales (IMU, del inglés Inertial Measurement Unit) o cámaras- o en la infraestructura -unidades de control, sensores para detectar situaciones del tráfico. La arquitectura presentada busca la escalabilidad para permitir de manera sencilla la inclusión de nuevos dispositivos que permitan mejorar las prestaciones. Para validar la solución propuesta, se presentan diferentes experimentos llevados a cabo con vehículos comerciales, algunos de ellos modificados para permitir el control automático de los mismos en la pista de pruebas del IAI-CSIC. Dichos experimentos incluyen situaciones habituales del tráfico como pueden ser la conducción en atascos, la gestión de preferencias en intersecciones sin señalización, la evasión de un peatón que se cruce en la carretera o la llegada a una curva peligrosa no señalizada. El sistema propuesto soluciona estas situaciones reales de tráfico de forma eficiente y segura. Como principales aportaciones se destacan el sistema de control local del tráfico al que se le dota de inteligencia para optimizar las comunicaciones inalámbricas, las mejoras conseguidas sobre la arquitectura de control de los vehículos y la presentación de sistemas para el control de situaciones de tráfico en entornos desestructurados

Sistema de control de tráfico para la coexistencia entre vehículos autónomos y manuales mediante comunicaciones inalámbricas

Premio Extraordinario de Doctorado 2012Los avances en el campo de los sistemas inteligentes de transporte (ITS, del inglés Intelligent Transportation Systems) en los últimos años han propiciado la aparición de sistemas que ayudan de manera significativa a los conductores facilitando su labor, relegándoles de tareas tediosas. No es demasiado utópico pensar en un futuro en vehículos completamente automatizados circulando por las carreteras. Sin embargo, se precisa de un sistema de transición desde los vehículos que actualmente circulan por las carreteras hasta los vehículos completamente automatizados y, por ende, la coexistencia entre ellos. En el presente trabajo de tesis doctoral se presenta el diseño, desarrollo e implementación de un sistema global para el control del tráfico con vehículos guiados por conductores humanos o automáticos basado en comunicaciones inalámbricas con un doble objetivo: en primer lugar, disminuir de manera significativa la congestión actual del tráfico, fundamentalmente en entornos urbanos, y en segundo lugar, presentar un sistema seguro que permita pensar en una reducción del número de accidentes en las carreteras o, al menos, mitigar las consecuencias. Para lograr los objetivos propuestos se utilizarán diversas fuentes de información ya sean ubicadas en los vehículos -sistemas de navegación global por satélite (GNSS, del inglés Global Navigation Satellite System), sistemas inerciales (IMU, del inglés Inertial Measurement Unit) o cámaras- o en la infraestructura -unidades de control, sensores para detectar situaciones del tráfico. La arquitectura presentada busca la escalabilidad para permitir de manera sencilla la inclusión de nuevos dispositivos que permitan mejorar las prestaciones. Para validar la solución propuesta, se presentan diferentes experimentos llevados a cabo con vehículos comerciales, algunos de ellos modificados para permitir el control automático de los mismos en la pista de pruebas del IAI-CSIC. Dichos experimentos incluyen situaciones habituales del tráfico como pueden ser la conducción en atascos, la gestión de preferencias en intersecciones sin señalización, la evasión de un peatón que se cruce en la carretera o la llegada a una curva peligrosa no señalizada. El sistema propuesto soluciona estas situaciones reales de tráfico de forma eficiente y segura. Como principales aportaciones se destacan el sistema de control local del tráfico al que se le dota de inteligencia para optimizar las comunicaciones inalámbricas, las mejoras conseguidas sobre la arquitectura de control de los vehículos y la presentación de sistemas para el control de situaciones de tráfico en entornos desestructurados

Autonomous vehicle control systems for safe crossroads

This article presents a cooperative manoeuvre among three dual mode cars – vehicles equipped with sensors and actuators, and that can be driven either manually or autonomously. One vehicle is driven autonomously and the other two are driven manually. The main objective is to test two decision algorithms for priority conflict resolution at intersections so that a vehicle autonomously driven can take their own decision about crossing an intersection mingling with manually driven cars without the need for infrastructure modifications. To do this, the system needs the position, speeds, and turning intentions of the rest of the cars involved in the manoeuvre. This information is acquired via communications, but other methods are also viable, such as artificial vision. The idea of the experiments was to adjust the speed of the manually driven vehicles to force a situation where all three vehicles arrive at an intersection at the same time

Fractional-Order-Based ACC/CACC Algorithm for Improving String Stability

International audienceTraffic flow optimization and driver comfort enhancement are the main contributions of an Adaptive Cruise Control (ACC) system. If communication links are added, more safety and shorter gaps can be reached performing a Cooperative-ACC (CACC). Although shortening the inter-vehicular distances directly improves traffic flow, it can cause string unstable behavior. This paper presents fractional-order-based control algorithms to enhance the car-following and string stability performance for both ACC and CACC vehicle strings, including communication temporal delay effects. The proposed controller is compared with state-of-the-art implementations, exhibiting better performance. Simulation and real experiments have been conducted for validating the approach

Mixing V2V- and non-V2V-equipped vehicles in car following

International audienceCooperative Adaptive Cruise Control (CACC) provides significant traffic flow improvements when a vehicle-to-vehicle (V2V) communication link exists with the preceding vehicle , but it degrades to an Adaptive Cruise Control (ACC) when this communication link is no longer available. This degradation occurs even if the information from another V2V-equipped vehicle ahead (different to the preceding one) is still available. This paper presents a novel car-following control system-Advanced Cooperative Adaptive Cruise Control (ACACC)-that benefits from the existing communication with this vehicle ahead in the string, reducing inter-vehicle gap whereas keeping string stability. The proposed control structure provides a hybrid behaviour between two CACC controllers with different time gaps according to the string position of the vehicle with the V2V communication link available. An stable hybrid behavior between both controllers is ensured through the Youla-Kucera parameterization. Simulation and real experiments show the proper behaviour of the designed control algorithm and a good performance compared to existing ACC/CACC controllers

Ultrasonic Sensors in Urban Traffic Driving-Aid Systems

Currently, vehicles are often equipped with active safety systems to reduce the risk of accidents, most of which occur in urban environments. The most prominent include Antilock Braking Systems (ABS), Traction Control and Stability Control. All these systems use different kinds of sensors to constantly monitor the conditions of the vehicle, and act in an emergency. In this paper the use of ultrasonic sensors in active safety systems for urban traffic is proposed, and the advantages and disadvantages when compared to other sensors are discussed. Adaptive Cruise Control (ACC) for urban traffic based on ultrasounds is presented as an application example. The proposed system has been implemented in a fully-automated prototype vehicle and has been tested under real traffic conditions. The results confirm the good performance of ultrasonic sensors in these systems

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

Modeling cooperative and autonomous adaptive cruise control dynamic responses using experimental data

International audienceVehicle longitudinal control systems such as (commercially available) autonomous Adaptive Cruise Control (ACC) and its more sophisticated variant Cooperative ACC (CACC) could potentially have significant impacts on traffic flow. Accurate models of the dynamic responses of both of these systems are needed to produce realistic predictions of their effects on highway capacity and traffic flow dynamics. This paper describes the develop-ment of models of both ACC and CACC control systems that are based on real experimental data. To this end, four production vehicles were equipped with a commercial ACC system and a newly developed CACC controller. The Intelligent Driver Model (IDM) that has been widely used for ACC car-following modeling was also implemented on the production vehicles. These controllers were tested in different traffic situations in order to measure the actual responses of the vehicles. Test results indicate that: (1) the IDM controller when implemented in our experimental test vehicles does not perceptibly follow the speed changes of the preceding vehicle; (2) strings of consecutive ACC vehicles are unstable, amplifying the speed variations of preceding vehicles; and (3) strings of consecutive CACC vehicles overcome these limitations, providing smooth and stable car following responses. Simple but accurate models of the ACC and CACC vehicle following dynamics were derived from the actual measured responses of the vehicles and applied to simulations of some simple multi-vehicle car following scenarios