http://wpage.unina.it/valerio.persico/pubs/CloudIoT_FGCS.pdf

Integration of Cloud computing and Internet of Things

Intelligent vehicles have increased their capabilities for highly and, even fully, automated driving under controlled environments. Scene information is received using onboard sensors and communication network systems, i.e., infrastructure and other vehicles. Considering the available information, different motion planning and control techniques have been implemented to autonomously driving on complex environments. The main goal is focused on executing strategies to improve safety, comfort, and energy optimization. However, research challenges such as navigation in urban dynamic environments with obstacle avoidance capabilities, i.e., vulnerable road users (VRU) and vehicles, and cooperative maneuvers among automated and semi-automated vehicles still need further efforts for a real environment implementation. This paper presents a review of motion planning techniques implemented in the intelligent vehicles literature. A description of the technique used by research teams, their contributions in motion planning, and a comparison among these techniques is also presented. Relevant works in the overtaking and obstacle avoidance maneuvers are presented, allowing the understanding of the gaps and challenges to be addressed in the next years. Finally, an overview of future research direction and applications is given.

A Review of Motion Planning Techniques for Automated Vehicles

Safety critical systems involve the tight coupling between potentially conflicting control objectives and safety constraints. As a means of creating a formal framework for controlling systems of this form, and with a view toward automotive applications, this paper develops a methodology that allows safety conditions—expressed as control barrier functions —to be unified with performance objectives—expressed as control Lyapunov functions—in the context of real-time optimization-based controllers. Safety conditions are specified in terms of forward invariance of a set, and are verified via two novel generalizations of barrier functions; in each case, the existence of a barrier function satisfying Lyapunov-like conditions implies forward invariance of the set, and the relationship between these two classes of barrier functions is characterized. In addition, each of these formulations yields a notion of control barrier function (CBF), providing inequality constraints in the control input that, when satisfied, again imply forward invariance of the set. Through these constructions, CBFs can naturally be unified with control Lyapunov functions (CLFs) in the context of a quadratic program (QP); this allows for the achievement of control objectives (represented by CLFs) subject to conditions on the admissible states of the system (represented by CBFs). The mediation of safety and performance through a QP is demonstrated on adaptive cruise control and lane keeping, two automotive control problems that present both safety and performance considerations coupled with actuator bounds.

https://ieeexplore.ieee.org/ielaam/9/7993115/7782377-aam.pdf

Control Barrier Function Based Quadratic Programs for Safety Critical Systems

The introduction of connected and autonomous vehicles will bring changes to the highway driving environment. Connected vehicle technology provides real-time information about the surrounding traffic condition and the traffic management center’s decisions. Such information is expected to improve drivers’ efficiency, response, and comfort while enhancing safety and mobility. Connected vehicle technology can also further increase efficiency and reliability of autonomous vehicles, though these vehicles could be operated solely with their on-board sensors, without communication. While several studies have examined the possible effects of connected and autonomous vehicles on the driving environment, most of the modeling approaches in the literature do not distinguish between connectivity and automation, leaving many questions unanswered regarding the implications of different contemplated deployment scenarios. There is need for a comprehensive acceleration framework that distinguishes between these two technologies while modeling the new connected environment. This study presents a framework that utilizes different models with technology-appropriate assumptions to simulate different vehicle types with distinct communication capabilities. The stability analysis of the resulting traffic stream behavior using this framework is presented for different market penetration rates of connected and autonomous vehicles. The analysis reveals that connected and autonomous vehicles can improve string stability. Moreover, automation is found to be more effective in preventing shockwave formation and propagation under the model’s assumptions. In addition to stability, the effects of these technologies on throughput are explored, suggesting substantial potential throughput increases under certain penetration scenarios.

Influence of connected and autonomous vehicles on traffic flow stability and throughput

Intelligent vehicle cooperation based on reliable communication systems contributes not only to reducing traffic accidents but also to improving traffic flow. Adaptive cruise control (ACC) systems can gain enhanced performance by adding vehicle-vehicle wireless communication to provide additional information to augment range sensor data, leading to cooperative ACC (CACC). This paper presents the design, development, implementation, and testing of a CACC system. It consists of two controllers, one to manage the approaching maneuver to the leading vehicle and the other to regulate car-following once the vehicle joins the platoon. The system has been implemented on four production Infiniti M56s vehicles, and this paper details the results of experiments to validate the performance of the controller and its improvements with respect to the commercially available ACC system.

/pdf/cooperative-adaptive-cruise-control-in-real-traffic-35mggeon75.pdf

Cooperative Adaptive Cruise Control in Real Traffic Situations

This paper presents the interaction protocols developed for execution of two common scenarios in daily traffic using cooperative automated vehicles. The first proposed scenario addresses merging of a (semi-)automated car on a highway within a platoon of (semi-)automated vehicles. The second scenario is an extension of the first scenario with a focus on a lane reduction where a platoon of automated vehicles merges into a second one on a different lane. The proposed interaction protocols are characterized by a sequence of maneuvers to execute the scenarios together with the corresponding communication message sets. Moreover, the vehicle control system should be equipped to implement these protocols. Therefore, the design strategy should address the interaction protocol as well as the control system design. The most important feature of the proposed design strategy is to decompose the scenarios into a sequence of basic maneuvers. This method provides a generic solution which can be implemented to other scenarios, too. Also, the thought behind the design approach is to follow the pattern that human drivers interact in similar daily traffic occasions as well as to ensure a distributed decision making mechanism where no fixed supervisor is required. In both scenarios, the platoon controllers are active to achieve the common control objective of platooning. However, for realization of the proposed scenarios, additional controllers are needed to perform the scenario-specific tasks.

Interaction Protocols for Cooperative Merging and Lane Reduction Scenarios

This paper presents a setup for cooperative adaptive cruise control for which feasibility of the actual implementation is one of the main objectives. The approach considers communication with the directly preceding vehicle only, can deal with heterogeneous traffic, accounts for communication delay, and enables graceful degradation to standard adaptive cruise control if communication fails. The stability of a string of vehicles is analyzed using a frequency-domain approach.

http://www.mate.tue.nl/mate/pdfs/10768.pdf

Towards On-the-Road Implementation of Cooperative Adaptive Cruise Control

Cooperative adaptive cruise control (CACC) improves road throughput by employing intervehicle wireless communications. The inherent communication time delay and vehicle actuator delay significantly limit the minimum intervehicle distance in view of string stability requirements. Hence, controller design needs to consider both delays, which result in a nonrational transfer function representation of the CACC-controlled string. Pade approximations can be applied to arrive at a finite-dimensional model, which allows for many standard control methods. Our objective is to provide a method to decide for the lowest possible order of the Pade approximation, which is sufficiently accurate in view of CACC (string) stability analysis. The constant time gap strategy and a one-vehicle look-ahead topology are adopted to develop a CACC stable string. First, based on the stable controller parameter region, a suitable order of Pade approximations of the vehicle actuator delay can been carried out in view of individual vehicle stability. Then, the minimum string-stable time gaps for a CACC system with both exact and approximated delays have been compared. The procedure with a Proportional-derivative controller to choose the approximation order of delays has been given, followed by the time-domain simulation validation.

Padé Approximation of Delays in Cooperative ACC Based on String Stability Requirements

Nowadays, throughput has become a limiting factor in road transport. An effective means to increase the road throughput is to decrease the intervehicle time gap. A small time gap, however, may lead to string instability, being the amplification of velocity disturbances in upstream direction. String-stable behavior is thus considered an essential requirement for the design of automatic distance control systems, which are needed to allow for safe driving at time gaps well below 1 s. However, the formal notion of string stability is not unambiguous in literature, since both stability interpretations and performance interpretations exist. Therefore, a novel definition for string stability of nonlinear cascaded systems is proposed, using input–output properties. This definition is shown to result in well-known string stability conditions for linear cascaded systems. Employing these conditions, string stability is obtained by a controller that uses wireless intervehicle communication to provide information of the preceding vehicle. The theoretical results are validated by implementation of the controller, known as Cooperative Adaptive Cruise Control, on a platoon of six passenger vehicles. Experiments clearly show that the practical results match the theoretical analysis, thereby indicating the practical feasibility for short-distance vehicle following.

Analysis and design of controllers for cooperative and automated driving

Cooperative adaptive cruise control (CACC) employs intervehicle wireless communications to realize short intervehicle distances and, hence, to improve road throughput. However, the vehicle actuator delay and communication delay have a significant effect on the (string) stability properties. Therefore, a Smith predictor has been applied to compensate for the vehicle actuator delay, while utilizing a proportional–derivative controller and a constant time gap spacing policy. The control actuation is conducted on a delay-free vehicle model to follow a preceding vehicle with a desired distance, such that the resulting scheme leads to individual vehicle stability independent of the vehicle actuator delay. Moreover, this approach allows for a smaller minimum string-stable time gap compared to without the compensator, thus taking full advantage of CACC. In addition, the Smith predictor has been adapted to take acceleration disturbances into account. The results are experimentally validated using a platoon of two passenger vehicles, illustrating the practical feasibility of this approach.

Jeroen Ploeg

Papers

Interaction Protocols for Cooperative Merging and Lane Reduction Scenarios

Towards On-the-Road Implementation of Cooperative Adaptive Cruise Control

Padé Approximation of Delays in Cooperative ACC Based on String Stability Requirements

Analysis and design of controllers for cooperative and automated driving

Smith Predictor Compensating for Vehicle Actuator Delays in Cooperative ACC Systems