Hilal Diab

A testing platform for cooperative vehicle platoon controllers

This paper presents a hardware implementation of a platoon of four 1:14 scaled trucks. For this experiment, each truck was equipped with sensors for the measurement of specific variables required for the control of the platoon. These variables were transmitted via WLAN to an MPC555 processor in which the controller as well as the incoming data were processed. Graphical User Interfaces (GUIs) have been developed to monitor the dynamic behavior of the system under full communication as well as under disturbances and to modify the parameters of the system online. To test the platform a cascade control structure has been proposed.

Safety Verification of a Controlled Cooperative Platoon Under Loss of Communication Using Zonotopes

Abstract This paper investigates the safety properties of a networked platoon of vehicles. The vehicles exchange information via a communication network that is subject to failure of single nodes or a complete loss of communication. An LMI-based controller is applied to maintain short distances between the vehicles. The system is modeled as a hybrid automaton, in which the continuous part represents the dynamical behavior of the platoon and the discrete part are spontaneous events related to the switching communication topology. For safety assessment, a reachability analysis of linear hybrid systems with uncertain inputs is applied. It consists of computing an approximation of the reachable set using zonotopes. In this paper, we propose a recursive scheme for the computation of the reachable set for hybrid systems with arbitrary transitions. We consider, as a study case, the worst case scenario corresponding to the transition from a fully functioning communication between the vehicles to a total loss of communication. We use the results of the verification to determine the minimum safe distances between the vehicles guaranteeing collision-free drive under network disturbances.

A platoon of vehicles approaching an intersection: A testing platform for safe intersections

Intersections are one of the most complex driving scenarios for an autonomous vehicle. When a platoon of autonomous vehicles following a leader approaches the intersection, the platoon should change its highway mode to other modes in order to cross the intersection safely. Therefore, the position, velocity and acceleration of the vehicles inside the platoon should be available. Furthermore, information about the position and velocity of other vehicles in the intersection area should be known too. The platoon controller should use all these information to decide which mode will be adopted. In fact, the platoon has to decide whether to stop, to pass or to split the platoon while crossing the intersection. This paper proposes a scaled testing platform of four electronically coupled vehicles equipped with a positioning system and an intersection management system. We tested different scenarios related to different crossing modes of the platoon. The experiments showed that we can change the platoon mode from a highway mode to an intersection drive efficiently.

Safety Verification of a Cooperative Vehicle Platoon with Uncertain Inputs Using Zonotopes

Abstract This paper presents an approach to safety verification of a controlled cooperative platoon of vehicles. To guarantee collision free operation, spacing errors must not exceed critical bounds. Our approach is based on the reachability analysis of linear systems subject to uncertain inputs. The reachable sets are represented by zonotopes. We propose an accurate approximation of the contribution of the uncertain inputs to the whole reachable set. This approach reduces the propagation of the over-approximation error and leads to tight approximation sets.

Control Design for Generalized Platoon Problems

Abstract This paper presents a generalized description of linear transport processes that allows for a derivation of common dynamic properties and a control layout for a wide set of applications. Based on the introduction of the system description of platoons and a proposition of suitable performance criteria a control layout is formulated which reduces the synchronization of a common motion of sub-systems to a stabilization problem of the platoon and optimizes the corresponding performance measures. Furthermore, the influence of communication topology and switching information access among platoon members is investigated. The proposed approach is applied to a vehicle platoon with one leading and three following vehicles and is analyzed through both simulations and physical experiments with model scale vehicles. The results show that the approach is also applicable to physical plants that can only be approximated by a linear platoon model. Zusammenfassung In diesem Beitrag wird eine verallgemeinerte Beschreibung von Transportprozessen vorgestellt, die eine Ableitung gemeinsamer Systemeigenschaften sowie die Auslegung von Regelungen für eine Vielzahl von Prozessen ermöglicht. Auf Basis der eingeführten Systembeschreibung von Kolonnen und der Formulierung geeigneter Gütekriterien wird ein Reglerentwurf vorgeschlagen, der die Synchronisierung einer gemeinsamen Bewegung aller Teilsysteme auf die Stabilixsierung der Kolonne zurückführt und eine optimale Lösung in Bezug auf die formulierten Güteanforderungen darstellt. Des Weiteren wird der Einfluss der Kommunikationstopologie und der schaltenden Änderung von Informationsverfügbarkeit innerhalb der Kolonne untersucht. Der vorgeschlagene Entwurf wird auf das Beispiel einer Fahrzeugkolonne mit einem Führungsfahrzeug und drei Folgefahrzeugen angewendet und durch Simulationen sowie durch Experimente an Modellfahrzeugen analysiert. Die Ergebnisse zeigen, dass sich das Verfahren auch auf physikalische Strecken, deren Dynamik lediglich durch lineare Modelle approximiert werden kann, anwenden lässt.

Design and implementation of a vehicle dynamics control system by means of torque vectoring for an autonomous vehicle

This paper describes to which extent the operational envelope of scaled vehicles can be extended by integrating a vehicle dynamics control system using torque vectoring. A detailed description for the construction of a mechatronic basis for an autonomous model car in a 1:10th scale is given. The design of the vehicle only uses standardized components and allows the most possible flexibility of controlling the vehicles dynamics behavior by applying individual driving moments to the wheels.

Reachability analysis for managing platoons at intersections

In this work we address the management of a platoon of vehicles passing an intersection. In such a situation we have to decide under which conditions the platoon can pass the intersection in its entirety while avoiding collisions. If this cannot be assured, the platoon should be stopped at the intersection line or possibly split. For this purpose a decision about the vehicle from which the platoon should be divided in two sub-platoons must be taken. In this case, the part ahead can drive safely through the intersection, while the second part must wait at the stop line for a permission to pass. The decision is made based on the results of reachability analysis of hybrid systems. The dynamics of the controlled platoon and the vehicle on the other side of the intersection is modeled as a linear time invariant system with uncertain input. For the computation of reachable sets we use our method based on zonotopes as approximation sets. We show how decisions to manage the platoon at the intersection under safety guarantees can be supported by the results of the reachability analysis and information about the intersection infrastructure.

On the Effects of Network Delays on an Energy-based Controller

Abstract In this paper, the design of an energy-based controller for a platoon of nonholonomic vehicles is presented and its performance is analysed for the case of random time delays in the network. The nonholonomic constraints of the models are taken into account during the design process by considering them in the goal virtual Lagrange function. The introductory section gives an overview of the energy methods for the case of mass point vehicles. Subsequently, the strategy is extended to apply to the case of nonholonomic vehicles. The controller is analysed by means of simulation tools in order to evaluate the effects of random Rayleigh distributed delays on the network.

Regelung und Sicherheitsanalyse einer Gruppe Massenpunktfahrzeuge mit Hilfe energiebasierter Methoden (Control and Safety Analysis of a Group of Point Mass Vehicles Using Energy Methods).

Zusammenfassung Dieser Beitrag beschreibt die energiebasierte Regelung einer Gruppe von Fahrzeugen, die als Massenpunkte in der Ebene modelliert werden. Es wird zuerst eine Umformung der kinetischen Energie durchgeführt, sodass die Komponenten der Geschwindigkeitsvektoren, welche die Abstände verändern, bei der Regelung unterschiedlich bestraft werden. Darüber hinaus werden virtuelle potentielle Energie und dissipative Terme hinzugefügt, um das System in einer Kolonnenkonfiguration zu stabilisieren. Zum Schluss werden ein Stabilitätsbeweis sowie eine Sicherheitsanalyse auf der Basis hybrider Automaten durchgeführt und die Ergebnisse vorgestellt.