Mohamed Marouf

Platooning control using visible light communications: A feasibility study

The major benefits of driving vehicles in controlled close formations such as platoons are that of increasing traffic fluidity and reducing air pollution. While Vehicle-toVehicle (V2V) communications is requisite for platooning stability, the existing radio communications technologies (e.g., the IEEE 802.11p) suffer from poor performance in highly dense road scenarios, which are exactly to be created by platooning. This paper studies the applicability of visible light communications (VLC) system for information exchange between the platoon members. A complete VLC model is built enabling precise calculations of Bit-Error-Rate (BER) affected by inter-vehicle distance, background noise, incidence angle and receiver electrical bandwidth. Based on our analytical model, the optical parameters suiting platooning application are defined. Finally, a SIMULINK model is developed to study the performances of a platooning longitudinal and lateral control, where VLC is used for V2V information exchange. Our study demonstrates the feasibility of VLC-based platooning control even in the presence of optical noise at significant levels and up to a certain road curvature.

Scheduling non-preemptive hard real-time tasks with strict periods

Non-preemptive real-time scheduling and the corresponding schedulability analyses have received considerable less attention in the research community, compared to preemptive real-time scheduling. However, non-preemptive scheduling is widely used in industry, especially in the case of hard real-time systems where missing deadlines leads to catastrophic situations and where resources must not be wasted. In many industries such as avionics tasks may have strict periods, i.e. the start times of their executions must be separated by a fixed period. Indeed, this strict periodicity is generally required by sensors and actuators which may have accurate periods. In this paper we consider separately the case where tasks have harmonic periods and the case where tasks have non-harmonic periods. Thus, the general case becomes a combination of both cases. In the harmonic case we give schedulability conditions to verify that a set of tasks is schedulable. In the non-harmonic case, in order to prove that a set of tasks is schedulable we propose local schedulability conditions that we apply iteratively to each task of the set in order to verify that this current task, added to a sub-set of tasks already scheduled, leads to a schedulable set of tasks.

Low-Speed Cooperative Car-Following Fuzzy Controller for Cybernetic Transport Systems

This paper describes the development of a Cooperative Adaptive Cruise Control (CACC) for the future urban transportation system at low-speed. The control algorithm was evaluated using two Cybecars as prototype vehicles. A longitudinal response model for the vehicles was developed to design the CACC system. The control algorithm was implemented on a fuzzy logic-based controller that has been tuned to minimize a cost function in order to get a trade-off between a proper car-following gap error and the smoothness of the control signal. The controller was firstly tested in simulation using the developed model. Then, the CACC was implemented in two Cybecars to validate the controller performance in real scenarios.

Enhancing the field of view limitation of Visible Light Communication-based platoon

Visible Light Communication (VLC) technology have recently been suggested as efficient supportive technology for platooning applications over short inter-vehicle distances. Though, ensuring the continuity of Line-of-Sight (LOS) of any optical-based applications is one of the most complex scenarios for an autonomous vehicle control, and still remains as an open challenge for Intelligent Transformation Systems (ITS). Exchanging information about the relative directional position of each member of the platoon, together with front and rear facing directions of each vehicle, can be very useful data for building a smooth geometrical-based compensation method, which results in ensuring that any increase in both incidence and irradiance optical angles will never exceed the Field of View (FOV) limitations and regardless of the trajectory shape. This paper propose a tracking alike compensation method of four vehicles equipped with positioning and VLC systems. We have simulated different scenarios related to different trajectories and compensation angles limits. The simulation results show that trajectories influence on the optical incidence and irradiance angles can be compensated efficiently and without deploying any tracking method.

Automatic parallel parking and platooning to redistribute electric vehicles in a car-sharing application

In car-sharing applications and during certain time slots, some parking parks become full whereas others are empty. To redress this imbalance, vehicle redistribution strategies must be elaborated. As automatic relocation cannot be in place, one alternative is to get a leader vehicle, driven by a human, which come to pick up and drop off vehicles over the stations. This paper deals with the vehicle redistribution problem among parking using this strategy and focuses on automatic parking and vehicles platooning. We present an easy exit parking controller and path planning based only on geometric approach and vehicles characteristics. Once the vehicle exits the parking, it joins a platoon of vehicles and follows it automatically to go to an empty parking space.

Schedulability analysis for a combination of non-preemptive strict periodic tasks and preemptive sporadic tasks

We consider the problem of fixed priority scheduling of non-preemptive strict periodic tasks in conjunction with sporadic preemptive tasks. There are few studies about the scheduling problem combining these two kinds of tasks. Moreover, only few results are available on scheduling non-preemptive strict periodic tasks since their performance analysis gives low success ratios, except in the case of harmonic tasks. Also, strict periodic tasks are of great importance since they are in charge for example of sensors/actuators or feedback control functions which are all critical in feedback control systems. Such tasks must have the highest priorities in order to guarantee a correct behavior of the control system. Preemptive sporadic tasks can be used for non critical functions and have lower priorities. We first investigate the scheduling problem of non-preemptive strict periodic tasks by recalling an existing schedulability condition. This results in defining the first release times of strict periodic tasks that preserves the strict periodicity constraints. We show that the schedule of strict periodic tasks can have transient and permanent phases. Then, assuming that some non-preemptive strict periodic tasks have been scheduled, we characterize the release times of the sporadic tasks that maximize their worst case response times. We prove that these release times can be restricted to the permanent phase. For preemptive sporadic tasks, we extend the classical worst case response time computation to take into account non-preemptive strict periodic tasks. Finally, we consider the particular case where some of the sporadic tasks are alternate tasks to primary strict periodic tasks for fault-tolerance.