Impact of Unreliable Communication on String Stability of Cooperative Adaptive Cruise Control

2019 ◽  
Author(s):  
Saina Ramyar ◽  
Abdollah Homaifar
Keyword(s):  
Adaptive Cruise Control ◽  
Cruise Control ◽  
String Stability ◽  
Cooperative Adaptive Cruise Control

Evaluation of Driver Car-Following Behavior Models for Cooperative Adaptive Cruise Control Systems

2017 ◽  
Vol 2622 (1) ◽  
pp. 84-95 ◽  
Author(s):  
Mizanur Rahman ◽  
Mashrur Chowdhury ◽  
Kakan Dey ◽  
M. Rafiul Islam ◽  
Taufiquar Khan
Keyword(s):  
Vehicle Dynamics ◽  
Adaptive Cruise Control ◽  
User Acceptance ◽  
Evaluation Framework ◽  
Cruise Control ◽  
String Stability ◽  
Maximum Acceleration ◽  
Car Following ◽  
Cooperative Adaptive Cruise Control ◽  
Behavior Models

A cooperative adaptive cruise control (CACC) system targeted to obtain a high level of user acceptance must replicate the driving experience in each CACC vehicle without compromising the occupant’s comfort. “User acceptance” can be defined as the safety and comfort of the occupant in the CACC vehicle in terms of acceptable vehicle dynamics (i.e., the maximum acceleration or deceleration) and string stability (i.e., the fluctuations in the vehicle’s position, speed, and acceleration). The primary objective of this study was to develop an evaluation framework for the application of a driver car-following behavior model in CACC system design to ensure user acceptance in terms of vehicle dynamics and string stability. The authors adopted two widely used driver car-following behavior models, ( a) the optimum velocity model (OVM) and ( b) the intelligent driver model (IDM), to prove the efficacy of the evaluation framework developed in this research for CACC system design. A platoon of six vehicles was simulated for three traffic flow states (uniform speed, speed with constant acceleration, and speed with constant deceleration) with different acceleration and deceleration rates. The maximum acceleration or deceleration and the sum of the squares of the errors of the follower vehicle speed were measured to evaluate user acceptance in terms of vehicle dynamics and string stability. Analysis of the simulation results revealed that the OVM performed better at modeling a CACC system than did the IDM in terms of acceptable vehicle dynamics and string stability.

Smooth-Switching Control-Based Cooperative Adaptive Cruise Control by Considering Dynamic Information Flow Topology

2020 ◽  
Vol 2674 (4) ◽  
pp. 444-458
Author(s):  
Anye Zhou ◽  
Siyuan Gong ◽  
Chaojie Wang ◽  
Srinivas Peeta
Keyword(s):  
Information Flow ◽  
Adaptive Cruise Control ◽  
Switching Control ◽  
Cruise Control ◽  
Flow Topology ◽  
Dynamic Information ◽  
String Stability ◽  
Kalman Predictor ◽  
Cooperative Adaptive Cruise Control ◽  
Smooth Switching

Vehicle-to-vehicle communications can be unreliable because of interference and information congestion, which leads to the dynamic information flow topology (IFT) in a platoon of connected and autonomous vehicles. Some existing studies adaptively switch the controller of cooperative adaptive cruise control (CACC) to optimize string stability when IFT varies. However, the difference of transient response between controllers can induce uncomfortable jerks at switching instances, significantly affecting riding comfort and jeopardizing vehicle powertrain. To improve riding comfort while maintaining string stability, the authors introduce a smooth-switching control-based CACC scheme with IFT optimization (CACC-SOIFT) by implementing a bi-layer optimization model and a Kalman predictor. The first optimization layer balances the probability of communication failure and control performance optimally, generating a robust IFT to reduce controller switching. The second optimization layer adjusts the controller parameters to minimize tracking error and the undesired jerk. Further, a Kalman predictor is applied to predict vehicle acceleration if communication failures occur. It is also used to estimate the states of preceding vehicles to suppress the measurement noise and the acceleration disturbance. The effectiveness of the proposed CACC-SOIFT is validated through numerical experiments based on NGSIM field data. Results indicate that the CACC-SOIFT framework can guarantee string stability and riding comfort in the environment of dynamic IFT.

Human-Aware Autonomous Control for Cooperative Adaptive Cruise Control (CACC) Systems

2015 ◽  
Author(s):  
Xujie Wang ◽  
Yue Wang
Keyword(s):  
Adaptive Cruise Control ◽  
Controller Design ◽  
Cruise Control ◽  
String Stability ◽  
Driving Experience ◽  
Traffic Efficiency ◽  
Cooperative Adaptive Cruise Control ◽  
Human Driver ◽  
Driving Assistance ◽  
System Controller

This paper discusses the design of a human-aware cooperative adaptive cruise control (CACC) system that (i) takes into account driver comfort in autonomous cruise control, and (ii) provides assistive corrections to avoid driver errors. To incorporate driver characteristics into system controller design, two self-learning algorithms are used to estimate driver’s preferred time headway. We then develop a human-like blending control for CACC based on a model predictive control (MPC)-type method, which integrates the driver comfort, traffic efficiency, and fuel economy criteria. Furthermore, a driving assistance controller is developed to help human driver to maintain string stability in platoon. Simulation results show that (i) the human-like CACC design can significantly improve driving experience, and (ii) with the help of the assistive controller, string stability is satisfied for both exclusively autonomous CACC and when the CACC switches to manual driving in a platoon.

scholarly journals Control Design, Stability Analysis, and Traffic Flow Implications for Cooperative Adaptive Cruise Control Systems with Compensation of Communication Delay

2020 ◽  
Vol 2674 (8) ◽  
pp. 638-652
Author(s):  
Yu Zhang ◽  
Yu Bai ◽  
Jia Hu ◽  
Meng Wang
Keyword(s):  
Traffic Flow ◽  
Local Stability ◽  
Adaptive Cruise Control ◽  
Control Design ◽  
Communication Delay ◽  
Cruise Control ◽  
String Stability ◽  
Cooperative Adaptive Cruise Control ◽  
Time Gap ◽  
Traffic Flow Stability

Communication delay is detrimental to the performance of cooperative adaptive cruise control (CACC) systems. In this paper, we incorporate communication delay explicitly into control design and propose a delay-compensating CACC. In this new CACC system, the semi-constant time gap (Semi-CTG) policy, which is modified on the basis of the widely-used CTG policy, is employed by a linear feedback control law to regulate the spacing error. The semi-CTG policy uses historical information of the predecessor instead of its current information. By doing so, communication delay is fully compensated, which leads to better stability performance. Three stability properties—local stability, string stability, and traffic flow stability—are analyzed. The local stability and string stability of the proposed CACC system are guaranteed with the desired time gap as small as the communication delay. Both theoretical analysis and simulation results show that the delay-compensating CACC has better string stability and traffic flow stability than the widely-used CACC system. Furthermore, the proposed CACC system also shows the potential for improving traffic throughput and fuel efficiency. Robustness of the proposed system against uncertainties of sensor delay and vehicle dynamics is also verified with simulation.

Robust Cooperative Adaptive Cruise Control Design for Connected Vehicles

2015 ◽  
Author(s):  
Mark Trudgen ◽  
Javad Mohammadpour
Keyword(s):  
Traffic Congestion ◽  
Adaptive Cruise Control ◽  
Connected Vehicles ◽  
Cruise Control ◽  
String Stability ◽  
Reduction Techniques ◽  
Stability Robustness ◽  
Cooperative Adaptive Cruise Control ◽  
And Performance ◽  
Viable Approach

In this paper, we design and validate a robust H∞ controller for Cooperative Adaptive Cruise Control (CACC) in connected vehicles. CACC systems take advantage of onboard sensors and wireless technologies working together in order to achieve smaller inter-vehicle following distances, with the overall goal of increasing vehicle throughput on busy highways, and hence serving as a viable approach to reduce traffic congestion. A group of connected vehicles equipped with CACC technology must also ensure what is known as string stability. This requirement effectively dictates that disturbances should be attenuated as they propagate along the platoon of following vehicles. In order to guarantee string stability and to cope with the uncertainties seen in the vehicle model used for a model-based CACC, we propose to design and implement a robust H∞ controller. Loop shaping design methodology is used in this paper to achieve desired tracking characteristics in the presence of competing string stability, robustness and performance requirements. We then employ model reduction techniques to reduce the order of the controller and finally implement the reduced-order controller on a simulation model demonstrating the robust properties of the closed-loop system.

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