Vehicular Fog Computing Enabled Real-time Collision Warning via Trajectory Calibration

Vehicular fog computing (VFC) has been envisioned as a promising paradigm for enabling a variety of emerging intelligent transportation systems (ITS). However, due to inevitable as well as non-negligible issues in wireless communication, including transmission latency and packet loss, it is still challenging in implementing safety-critical applications, such as real-time collision warning in vehicular networks. In this paper, we present a vehicular fog computing architecture, aiming at supporting effective and real-time collision warning by offloading computation and communication overheads to distributed fog nodes. With the system architecture, we further propose a trajectory calibration based collision warning (TCCW) algorithm along with tailored communication protocols. Specifically, an application-layer vehicular-to-infrastructure (V2I) communication delay is fitted by the Stable distribution with real-world field testing data. Then, a packet loss detection mechanism is designed. Finally, TCCW calibrates real-time vehicle trajectories based on received vehicle status including GPS coordinates, velocity, acceleration, heading direction, as well as the estimation of communication delay and the detection of packet loss. For performance evaluation, we build the simulation model and implement conventional solutions including cloud-based warning and fog-based warning without calibration for comparison. Real-vehicle trajectories are extracted as the input, and the simulation results demonstrate that the effectiveness of TCCW in terms of the highest precision and recall in a wide range of scenarios

Lähestymistapa autonomiseen törmäyksenestoon Monorail-kuljetinjärjestelmässä

Collision Avoidance Systems are utilized both in industry and traffic in attempt to prevent material losses and injuries. These systems are implemented using sensors, communication systems or a combination of these. The most used sensors in collision avoidance applications are optical, electromagnetic and ultrasonic sensors. The communicationbased systems use both wireless and wired communications utilizing various protocols. This document describes the process of creating a prototype of a sensor-based Collision Avoidance System for Cimcorp Monorail Transfer system. Monorail Transfer is an automatic transportation system used in tire manufacturing plants for moving the tires between different process stations. It consists of a rail, which is either fastened into the roof of the plant or into a leg-like support structure, carriers which move along the rail and a cell controller. The aim is to prevent the collisions between the carriers and between carriers and other objects. The aim of the work is to have a functional prototype of an autonomous, sensor-based Collision Avoidance System which does not depend on Wi-Fi. The work begins with introducing the concept of Monorail Transfer in detail. Next the technologies behind the existing collision avoidance systems in industry and traffic are reviewed. The sensor types used in the implementations are identified and reviewed. Their suitability for the Monorail is considered. It is found that electromagnetic and optical sensors would be most suitable for the system. Electromagnetic sensors are discarded due to their high price and power consumption. Communication-based systems are reviewed. The Monorail Transfer’s current Collision Avoidance System is studied. After the theoretical part the new system is designed after defining its requirements. The sensors are chosen and reviewed. A Raspberry Pi 2 model B is chosen for pre-processing the sensor data prior to introducing it to the PLC’s in the Monorail Transfer. The Collision Avoidance software is programmed in Node.js, the communications between the PLC and Raspberry Pi are programmed in Node.js and the Graphical User Interface is implemented using HTML5, CSS and JS. The system is tested thoroughly and modified according to the findings. The prototype is found to be functional. Finally the document ends with conclusions about the implemented prototyp