Cooperative adaptive cruise control (original) (raw)
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Cooperative adaptive cruise control, design and experiments
Proceedings of the 2010 American Control Conference, 2010
The design of a CACC system and corresponding experiments are presented. The design targets string stable system behavior, which is assessed using a frequency-domain-based approach. Following this approach, it is shown that the available wireless information enables small inter-vehicle distances, while maintaining string stable behavior. The theoretical results are validated by experiments with two CACC-equipped vehicles. Measurement results showing string stable as well as string unstable behavior are discussed.
Design and experimental evaluation of cooperative adaptive cruise control
2011 14th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2011
Road throughput can be increased by driving at small inter-vehicle time gaps. The amplification of velocity disturbances in upstream direction, however, poses limitations to the minimum feasible time gap. 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. Theoretical analysis reveals that this requirement can be met using wireless intervehicle communication to provide real-time information of the preceding vehicle, in addition to the information obtained by common Adaptive Cruise Control (ACC) sensors. In order to validate these theoretical results and to demonstrate the technical feasibility, the resulting control system, known as Cooperative ACC (CACC), is implemented on a test fleet consisting of six passenger vehicles. Experiments clearly show that the practical results match the theoretical analysis, thereby indicating the possibilities for short-distance vehicle following.
Lp String Stability of Cascaded Systems: Application to Vehicle Platooning
IEEE Transactions on Control Systems Technology, 2000
Nowadays, throughput has become a limiting factor in road transport. An effective means to increase the road throughput is to employ a small intervehicle time gap using automatic vehicle-following control systems. String stability, i.e., the disturbance attenuation along the vehicle string, is considered an essential requirement for the design of those systems. However, the formal notion of string stability is not unambiguous in literature, since both stability 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. The theoretical results are experimentally validated using a platoon of six passenger vehicles equipped with cooperative adaptive cruise control.
A receding horizon approach to string stable cooperative adaptive cruise control
2011 14th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2011
A time domain approach to a "string stable", i.e., capable of attenuating acceleration shockwaves, cooperative adaptive cruise control is proposed in this paper. A receding horizon scheme is adopted to design a controller which attenuates acceleration shockwaves generated by the preceding vehicle while avoiding rear-end collisions. The classical definition of string stability in frequency domain is revised in the time domain and a new criterion for predecessor-follower string stability based on the acceleration signals is defined and used. Simulation and experimental results are presented to show the effectiveness of the proposed method.
Vehicle System Dynamics, 2002
This paper presents experimental results, analytical findings, and simulation evaluations pertaining to the longitudinal dynamics and headway performance of strings of vehicles with and without adaptive cruise control (ACC) systems. It focuses on the amplification of speed disturbances along a string of vehicles, i.e., the stability of string behavior. The work describes measurement, analysis, and simulation tools that are suitable for use in evaluating the impact of ACC system characteristics on traffic flow.
Cooperative adaptive cruise control: Tradeoffs between control and network specifications
2011 14th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2011
In this study, we consider a Cooperative Adaptive Cruise Control (CACC) system which regulates inter-vehicle distances in a vehicle string. Improved performance can be achieved by utilizing information exchange between vehicles through wireless communication besides local sensor measurements. However, wireless communication introduces networkinduced effects that may compromise the performance of the CACC system. Therefore, we approach the design of a CACC system from a Networked Control System (NCS) perspective. Network-induced imperfections in a NCS are mainly due to limited bandwidth of the network, multiple nodes sharing the same medium, and other limitations such as transmission delays and losses. Tradeoffs between CACC performance and network specifications need to be made for achieving desired performance under these network-induced constraints. In this paper, we present a NCS modelling framework that incorporates the effect of sample-and-hold and network delays that occur due to wireless communication. Moreover, we employ this model to study the so-called string stability performance of the string in which vehicles are interconnected by a vehicle following control law and a constant time headway spacing policy. Specifically, we study how string stability is affected by network-induced effects such as delays.
Cooperative Adaptive Cruise Control (Cacc) Definitions and Operating Concepts
Cooperative Adaptive Cruise Control (CACC) includes multiple concepts of communicationenabled vehicle following and speed control. This paper presents definitions and classifications to help clarify the distinctions among different types of automatic vehicle following control that are often conflated with each other. A distinction is made between V2V CACC, based on vehicle-vehicle cooperation, and I2V CACC, in which the infrastructure provides information or guidance to the CACC system (such as the target set speed value). In V2V CACC, communication provides enhanced information so that vehicles can follow their predecessors with higher accuracy, faster response, and shorter gaps, resulting in enhanced traffic flow stability and possibly improved safety. A further distinction is made between CACC, which uses constant-time-gap vehicle following (forming CACC strings), and automated platooning, which uses tightly-coupled, constant-clearance, vehicle-following strategies. Although ACC ...
String Stability of a Vehicular Platoon With the Use of Macroscopic Information
IEEE Transactions on Intelligent Transportation Systems, 2021
The paper investigates the possibility of using macroscopic information to improve control performance of a vehicular platoon composed of autonomous vehicles. A mesoscopic traffic modeling framework is proposed, and closed loop String Stability is achieved by exploiting Input-to-State Stability (ISS) for the analysis of the platoon. Examples of mesoscopic control laws are illustrated and simulations show the effectiveness of our approach in ensuring String Stability and improving the platoon behavior.
Longitudinal Control of a Platoon of Road Vehicles Equipped with Adaptive Cruise Control System
Mehran University Research Journal of Engineering and Technology, 2012
Automotive vehicle following systems are essential for the design of automated highway system. The problem associated with the automatic vehicle following system is the string stability of the platoon of vehicles, i.e. the problem of uniform velocity and spacing errors propagation. Different control algorithm for the longitudinal control of a platoon are discussed based on different spacing policies, communication link among the vehicles of a platoon, and the performance of a platoon have been analysed in the presence of disturbance (noise) and parametric uncertainties. This paper presented the PID (Proportional Integral Derivative) feedback control algorithm for the longitudinal control of a platoon in the presence of noise signal and investigates the performance of platoon under the influence of sudden acceleration and braking in severe conditions. This model has been applied on 6 vehicles moving in a platoon. The platoon has been analysed to retain the uniform velocity and safe s...